Treatment, prevention and control of anthrax disease in cattle

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Treatment, prevention and control of anthrax disease in cattle

Treatment, prevention and control of anthrax disease in cattle Anthrax is an infectious soil-borne disease caused by Bacillus anthracis, a relatively large spore-f The bacteria enter the body via a cut or graze.
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Different types of anthrax infection
Anthrax can target various body parts, including:

Cutaneous anthrax – skin is the most commonly affected body part, occurring in about 95 per cent of cases. The skin becomes itchy then develops a sore that turns into a blister. The blister (vesicle) may break and bleed. Within two to seven days, the broken blister becomes a sunken, dark-coloured or black scab

which is usually painless. Without treatment, the infection can spread to the lymph nodes or blood (septicaemia). Death is rare with the right antibiotic treatment. The mortality rate from untreated cutaneous anthrax is 5–20 per cent. Pulmonary anthrax – a rare lung infection that can occur when bacterial spores are inhaled. At first, the infection seems like a mild upper respiratory tract infection, such as a cold or flu. The person’s health rapidly deteriorates over the next few days with severe breathing problems and shock. Without treatment, the mortality rate is 70 to 80 per cent. In many cases, pulmonary anthrax is fatal even when treated. Intestinal anthrax – very rare in developed countries. It occurs if a person eats the undercooked meat of an infected animal, usually one that has died in the field. Early symptoms include nausea, vomiting, vomiting blood, diarrhoea and high temperature. If the infection spreads to the blood (septicaemia), the death rate is between 25 and 60 per cent.

09/09/2022

Infection control
For animals and humans, anthrax is a reportable disease in the United States. Local and state health departments, federal animal health officials, and the CDC's National Center for Infectious Diseases, Meningitis and Special Pathogens Branch should immediately be notified of any suspected cases. In addition, diagnostic laboratories should be informed that anthrax is a possible diagnosis when specimens are submitted, to ensure that safe processing protocols are followed.
Management of anthrax in livestock includes quarantine of the affected herd, removal of the herd from the contaminated pasture (if possible), vaccination of healthy livestock, treatment of livestock with clinical signs of disease, disposal of contaminated carcasses (preferably by burning), and incineration of bedding and other material found near the carcass. Because antibiotic treatment has been shown to interfere with response to the Sterne vaccine in animals, animals receiving concurrent antibiotic treatment should be revaccinated after the antibiotic regimen has been completed. Only one case of human-to-human transmission has been reported, therefore, experts believe that standard barrier isolation precautions are sufficient for healthcare workers who are in contact with anthrax patients.

09/09/2022

Prevention
Animal vaccination programs have reduced animal mortality from this disease drastically and, as cases of animal disease have decreased, human cases resulting from animal exposure have decreased as well. An approved vaccine is not available for dogs or cats. Animal vaccines have not been approved for and should not be administered to humans. A human vaccine is available but not readily accessible, and population-wide vaccination in the United States has not been recommended because risk has been considered to be low. In countries where anthrax is common, humans should avoid unnecessary contact with livestock and contaminated animal products and should not consume meat that has not been properly inspected and cooked. Postexposure prophylaxis may be achieved through long-term (60 days) oral administration of ciprofloxacin, doxycycline, or amoxicillin. Strains identified as involved in recent exposures in the United States are susceptible to doxycyline and it has recently been recommended as the drug of choice for prophylaxis for people. In addition to receiving antibiotics, it has been recommended that exposed persons be immunized.

09/09/2022

Treatment
Because the course of the disease is so rapid, prompt administration of appropriate antibiotics is essential. Most naturally occurring anthrax strains are susceptible to penicillins, and penicillins have been considered the first line of defense against anthrax. Doxycycline is considered to be a suitable alternative. When natural anthrax affects large animals (e.g., cattle, sheep, goats, swine, and horses), antibiotics of choice include penicillin and oxytetracycline. For small animals, amoxicillin, doxycycline, and enrofloxacin have been recommended; however, their effectiveness is not well documented. Because antibiotic-resistant strains can be readily isolated in laboratories, experts have suggested that ciprofloxacin may be the drug of choice when terrorism is suspected as the source of B. anthracis, at least until antibiotic susceptibilities can be determined. The strain of B. anthracis recently isolated in the United States has been shown to be susceptible to doxycycline, ciprofloxacin, and several other antibiotics.

Cattle, sheep, and goats—Clinical signs of peracute anthrax in cattle, sheep, and goats include staggering, trembling, b...

06/09/2022

26/08/2022

Treatment
Due to the rapidity of the disease treatment is seldom possible, although high doses of penicillin have been effective in the later stages of some outbreaks.

Prevention
Infection is usually acquired through the ingestion of contaminated soil, fodder or compound feed. Anthrax spores in the soil are very resistant and can cause disease when ingested even years after an outbreak. The spores are brought to the surface by wet weather, or by deep tilling, and when ingested or inhaled by ruminants the disease reappears.

Where an outbreak has occurred, carcases must be disposed of properly, the carcase should not be open (exposure to oxygen will allow the bacteria to form spores) and premises should be quarantined until all susceptible animals are vaccinated.
Vaccination in endemic areas is very important. Although vaccination will prevent outbreaks veterinary services sometimes fail to vaccinate when the disease has not appeared for several years. But because the spores survive for such lengthy periods, the risk is always present.
Anthrax is a disease listed in the World Organisation for Animal Health (OIE) Terrestrial Animal Health Code, 2011, (Article 1.2.3) and must be reported to the OIE (Chapter 1.1.2 – Notification of Diseases and Epidemiological Information).

26/08/2022

Cattle, sheep, and goats—Clinical signs of peracute anthrax in cattle, sheep, and goats include staggering, trembling, breathing difficulty, convulsions, and death. Progression of the disease is rapid and premonitory signs may go unnoticed; often animals are found dead, bloated, and without rigor mortis. Blood may fail to clot because of a toxin released by B. anthracis. Acute anthrax manifests itself in high fevers (up to 107 F), excitement, increased heart rate, deepening of respiration, followed by depression, incoordination, cessation of rumination, reduction in milk production, discolored milk (blood-tinged or deep yellow), bloody discharges, respiratory distress, convulsions, abortion, and death within 48 to 72 hours. Subcutaneous swelling and edema, usually involving the ventral aspect of the neck (brisket), thorax, shoulders, perineum and flank, are characteristic of chronic anthrax infection.

26/08/2022

The disease most often occurs in herbivores (e.g., cattle, sheep, goats, camels, antelopes), but can also occur in humans and other warm-blooded animals. Carnivores (e.g., dogs, cats, lions) and omnivores (e.g., swine) may become infected by eating undercooked meat from infected animals; however, many carnivores appear to have a natural resistance. Birds also appear to be at low risk for anthrax, but there are reports of the disease developing in ostriches, crows, canaries, and ducks. Anthrax spores have been isolated from the crops of sparrows, and birds of prey (e.g., vultures) have been implicated in the spread of anthrax spores through f***l contamination. Amphibians, reptiles, and fish are not directly susceptible. Anthrax is most common in temperate agricultural regions. Areas of high risk include South and Central America, Southern and Eastern Europe, Africa, Asia, the Caribbean, and the Middle East. In the United States, natural incidence is extremely low, although outbreaks have been reported in California, Louisiana, Mississippi, Nebraska, North Dakota, Oklahoma, South Dakota, and Texas. Outbreaks usually occur after periods of drought followed by heavy rains. Circumstantial evidence exists that humans are moderately resistant to anthrax. Anthrax is more often a risk in countries with minimally effective public health programs.

26/08/2022

Anthrax is caused by Bacillus anthracis, a spore-forming bacterium. Spores give B. anthracis its ability to survive in the soil for years to decades. The name is derived from the Greek word for coal, anthrakis, because the cutaneous form of the disease causes black, coal-like skin lesions.

08/08/2022

Domestic and wild animals can become infected when they breathe in or ingest spores in contaminated soil, plants, or water. These animals can include cattle, sheep, goats, antelope, and deer. In areas where domestic animals have had anthrax in the past, routine vaccination can help prevent outbreaks.

08/08/2022

03/08/2022

Public health risk
More than 95% of human anthrax cases are of the cutaneous form and result from handling infected carcasses or the hides, hair, meat, or bones from such carcasses.
In humans, anthrax manifests itself in three distinct patterns (cutaneous, gastrointestinal and inhalational). The most common is a skin infection, where people become infected handling animals or animal products that contain spores. This can happen to veterinarians, agricultural workers, livestock producers or butchers dealing with sick animals, or when infection has been spread by wool or hides.
Bacillus anthracis is not invasive and requires a lesion to infect. The spores enter the body through cuts or scratches in the skin and cause a local infection that if not controlled may spread throughout the body. The digestive form occurs when the spores are eaten. Tragically, people who lose their animals may also lose their lives trying to salvage something and consuming the meat from an animal that died. Potentially the most deadly form is by inhalation. This has been called ‘wool sorters’ disease’ because spores on hides or hair can be inhaled. While inhalation anthrax is rare in nature, anthrax spores have been developed and used as a biological weapon. Clearly, preventing the disease in animals will protect human public health.
Clinical signs
Peracute, acute, subacute and, rarely, chronic forms of the disease are reported. Antemortem clinical signs may be virtually absent in peracute and acute forms of the disease. Meanwhile, the only sign in chronic form may be enlarged lymph glands.
Ruminant animals are often found dead with no indication that they had been ill. In this acute form, there may be high fever, muscle tremors and difficult breathing seen shortly before the animal collapses and dies. Unclotted blood may exude from body openings and the body may not stiffen after death. Subacute form may be accompanied by progressive fever, depression, inappetence, weakness, prostration and death.
In horses and (on occasions) in ruminants there may be digestive upsets and colic, fever, depression and sometimes swelling. These symptoms may last for up to four days before death results.
In carnivores when the animal feeds on an infected source there may be an intestinal form of the disease with fever and cramps from which animals sometimes recover.
Diagnosis
Anthrax is diagnosed by examining blood (or other tissues) for the presence of the bacteria. Samples must be collected carefully to avoid contamination of the environment and to prevent human exposure to the bacteria. Blood samples from relatively fresh carcasses will contain large numbers of B. anthracis, which can be seen under a microscope, cultured and isolated in a laboratory, or detected by rapid tests, e.g. polymerase chain reaction (PCR).
The WOAH Manual of Diagnostic Tests and Vaccines for Terrestrial Animals describes both the laboratory procedures to detect anthrax and the accepted methodology for production of vaccines.
Prevention and control
In addition to antibiotic therapy and immunisation, specific control procedures are necessary to contain the disease and prevent its spread. In particular:
the proper disposal of dead animals is critical;
the carcass should not be opened, since exposure to oxygen will allow the bacteria to form spores
premises are to be quarantined until all susceptible animals are vaccinated and all carcasses disposed of preferably by incineration or alternatively by deep burial with quick lime.
cleaning and disinfection are important as is control of insects and rodents.
Vaccination in endemic areas is very important. WOAH spells out the requirements for the manufacture and quality control of animal vaccines, in the WOAH Manual of Diagnostic Tests and Vaccines. Although vaccination will prevent outbreaks, Veterinary Services sometimes fail to vaccinate when the disease has not appeared for several years. But because the spores survive for such lengthy periods, the risk is always present.
Though anthrax is quite susceptible to antibiotic therapy, the clinical course is often so rapid that there may not be the opportunity to treat affected animals. Early detection of outbreaks, quarantine of affected premises, destruction of diseased animals and fomites, and implementation of appropriate sanitary procedures at abattoirs and dairy factories will ensure the safety of products of animal origin intended for human consumption.

03/08/2022

Transmission and spread
Anthrax typically does not spread from animal to animal nor from person to person.
The bacteria produce spores on contact with oxygen. These spores are extremely resistant and survive for years in soil, or on wool or hair of infected animals. If ingested or inhaled by an animal, or after entering through cuts in the skin, they can germinate and cause disease. Because the blood of infected animals sometimes fails to clot and may leak from body orifices, insects can spread the bacteria to other animals.
Carnivores and humans can become infected by eating meat from an infected animal. Typically, however, animals become infected by ingesting spores that are in the soil or in feed.

03/08/2022

Anthrax is a disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax spores in the soil are very resistant and can cause disease when ingested even years after an outbreak. The spores are brought to the surface by wet weather, or by deep tilling, and when ingested by ruminants the disease reappears. Anthrax occurs on all the continents and commonly causes high mortality, primarily in domestic and wild herbivores as well as most mammals and several bird species. Anthrax is a WOAH-listed disease and must be reported to the WOAH as indicated in its Terrestrial Animal Health Code. In humans, anthrax manifests itself in three distinct patterns (cutaneous, gastrointestinal and inhalational). The most common is a skin infection, where people become infected handling animals or animal products that contain spores. This can happen to veterinarians, agricultural workers, livestock producers or butchers dealing with sick animals, or when infection has been spread by wool or hides. Anthrax is a preventable disease by vaccines and can be treated with antibiotics, however specific control procedures on carcasses disposal are necessary to contain the disease and prevent its spread.

29/04/2022

Hoofed animals, such as deer, cattle, goats, and sheep, are the main animals affected by this disease. They usually get the disease by swallowing anthrax spores while grazing on pasture contaminated (made impure) with anthrax spores.

29/04/2022

Causes
It is very rare that people get anthrax infection through natural causes. However, anthrax can be produced in laboratories and may be used as an agent of biological warfare. Anthrax is used in this manner because of the serious disease that results when the anthrax spores are inhaled. Inhaled anthrax often causes death if it's not treated in the early stages, which is why it is very important to recognize the symptoms of this infection (see "Symptoms and Complications").
The most common type of anthrax infection is cutaneous (on the skin) anthrax. In fact, this accounts for over 95% of naturally-occurring anthrax infections. Cutaneous anthrax infection may take place when someone handles animals or animal products (wool or other woven materials) that are contaminated with anthrax, or if someone handles materials that have been intentionally contaminated with anthrax.
It is quite rare for meat to be contaminated with the bacteria that causes anthrax in North America. Therefore, intestinal anthrax is very rare on this continent.

29/04/2022

Making the Diagnosis
Anthrax is diagnosed by taking samples from blood, respiratory secretion, or from any skin sores. The samples are sent to a laboratory to determine if they contain the bacteria that cause anthrax. The results are usually available about 2 days after the sample is taken.
Blood tests can determine if a person has come in contact with the bacteria that cause anthrax. Antibodies (proteins that fight off substances the body sees as foreign) to the bacteria will have been produced by the body's immune system, and they can be detected by a laboratory test.
People can be exposed to the bacteria that cause anthrax without becoming sick. Your doctor will evaluate your risk of exposure. However, if a test comes back positive, that person should be treated for anthrax in case the infection is in the early stages, before symptoms are evident.

29/04/2022

Ahthrax disease epidemiology
Anthrax is primarily a zoonotic disease in herbivores caused by a bacterium called Bacillus anthracis. Humans generally acquire the disease directly or indirectly from infected animals, or through occupational exposure to infected or contaminated animal products. Anthrax in humans is not generally regarded as contagious, although rare records of person-to-person transmission exist. Anthrax bacteria can survive in the environment for decades by forming spores. In its most common natural form called cutaneous anthrax (over 95% of cases), it creates dark sores on the skin, from which it derives its name, after the Greek word for coal.
Worldwide, the estimated incidence of human anthrax decreased from between 20,000 - 100,000 cases per year in 1958, to 2,000 per year during the 1980s. In the Eastern Mediterranean region outbreaks of human anthrax have been reported from Afghanistan, the Islamic Republic of Iran, Iraq, Morocco, Pakistan and Sudan. Additionally, Bacillus anthracis has always been high on the list of potential agents with respect to biological warfare and bioterrorism, having been used in that context on at least two occasions.
Control of anthrax among humans depends on the integration of veterinary and human health surveillance and control programmes. Routine cross-notification between the veterinary and human health surveillance systems and close collaboration between the two health sectors is particularly important during epidemiological and outbreak investigations.
Epidemiologists are often called "disease detectives," using many of the same methods as regular detectives to determine the cause of disease outbreaks, epidemics (i.e., larger excess in disease cases), or even pandemics (i.e., worldwide excess in disease cases). The anthrax outbreak in the United States which occurred during the latter part of 2001 has many of the same characteristics as a typical outbreak. What is different, however, is that there was no transmission from infected to susceptible persons that linked one case with another. Instead, all of the cases were generated by a terrorist or group of terrorists who sent letters containing anthrax spores through the postal system. These spores -- very small in size -- typically entered the skin or lungs or victim when the envelop was handled or opened, when coming in contact with an environment where envelopes had previously been handled or opened, or when passing through small holes in unopened envelops.
Intentionally infecting others with a deadly disease is a criminal matter, typically addressed by the police. Because the cases occurred in more than one state and involved the United States Postal System, the Federal Bureau of Investigation (FBI) was assigned as police detectives. Yet harm to the victims (namely, sickness and death) was caused by Bacillus anthracis, requiring knowledgeable disease rather than police detectives. This role was filled by epidemiologists from the United States Centers for Disease Control
While police detectives and disease detectives employ similar methods of investigation, the use of their findings is far different. Police detectives typically keep information secret or under wraps, allowing them to build a legal case against the alleged criminal. Eventually the information becomes public, but only when presented in a court of law. Their intent in the American legal system is to convict and then punish the criminal, with hope that such actions will prevent future crimes.
Disease detectives typically have a different goal, although related. They usually try to figure out what went wrong in a social or physical environment, identifying factors that allow a disease agent to generating an outbreak or epidemic. The goal of the disease detective is first to contain the outbreak and then to educate people on how to prevent similar outbreaks in the future. By necessity, these containment and education efforts involve the general public. Thus disease detectives work closely with the news media who as effective speakers and writers are best able to transmit educational messages. Thus disease detectives tend to be more open and collaborative then police detectives. When faced with a bioterrorist, however, police detectives and disease detectives share a goal, namely to find and stop the responsible terrorist or group of terrorists. The nature and occasional difficulties of such collaboration are described in the Anthrax media

29/04/2022

Anthrax disease occurrence
Anthrax is considered endemic in livestock in Georgia. In 2007, the annual vaccination became the responsibility of livestock owners, while contracting of private veterinarians was not officially required. Six years later, due to increase in human outbreaks associated with livestock handling, there is a need to find out the risk factors of livestock anthrax in Georgia.
Anthrax is a zoonotic infection caused by the gram-positive rod Bacillus anthracis. Most cases of anthrax are cutaneous (95%); the remaining cases are inhalational (5%) and gastrointestinal (< 1%). Anthrax caused by inhalation is usually fatal, and symptoms usually begin days after exposure. Bioterrorism must be suspected in any case of inhalational anthrax.

29/04/2022

Anthrax is a bacterial disease caused by the spore– forming Bacillus anthracis, a Gram-positive, rod-shaped bacterium the only obligate pathogen in the large genus Bacillus.
2.1.1. Cycle of infection
When conditions are not conducive to growth and multiplication of the vegetative forms of B. anthracis, they start to form spores. Sporulation requires the presence of free oxygen. In the natural situation, this means the vegetative cycles occur within the low oxygen environment of the infected host and, within the host, the organism is exclusively in the vegetative form. Once outside the host, sporulation commences upon exposure to the air and the spore forms are essentially the exclusive phase in the environment.
It is very largely through the uptake of spores from the environment that anthrax is contracted. The cycle of infection is illustrated in Fig. 1. Within the infected host the spores germinate to produce the vegetative forms which multiply, eventually killing the host (see chapter 5). A proportion of the bacilli released by the dying or dead animal into the environment (usually soil under the carcass) sporulate, ready to be taken up by another animal. This uptake by the next host may happen at any time, from less than one hour to many decades later.
Cycle of infection in anthrax. The spore is central to the cycle, although vegetative forms may also play a role in establishing infection when, for example, humans or carnivores eat meat from an animal that died of anthrax or when biting flies transmit

17/11/2021

Anthrax disease
Anthrax is a disease that affects humans and animals. In Ethiopia, anthrax is a reportable disease and assumed to be endemic, although laboratory confirmation has not been routinely performed until recently. We describe the findings from the investigation of two outbreaks in Amhara region.
Methods: Following reports of suspected outbreaks in Wag Hamra zone (Outbreak 1) and South Gondar zone (Outbreak 2), multi-sectoral teams involving both animal and public health officials were deployed to investigate and establish control programs. A suspect case was defined as: sudden death with rapid bloating or bleeding from orifice(s) with unclotted blood (animals); and signs compatible with cutaneous, ingestion, or inhalation anthrax ≤7 days after exposure to a suspect animal (humans). Suspect human cases were interviewed using a standard questionnaire. Samples were collected from humans with suspected anthrax (Outbreak 1 and Outbreak 2) as well as dried meat of suspect animal cases (Outbreak 2). A case was confirmed if a positive test was returned using real-time polymerase chain reaction (qPCR).
Results: In Outbreak 1, a total of 49 cows died due to suspected anthrax and 22 humans developed symptoms consistent with cutaneous anthrax (40% attack rate), two of whom died due to suspected ingestion anthrax. Three people were confirmed to have anthrax by qPCR. In Outbreak 2, anthrax was suspected to have caused the deaths of two livestock animals and one human. Subsequent investigation revealed 18 suspected cases of cutaneous anthrax in humans (27% attack rate). None of the 12 human samples collected tested positive, however, a swab taken from the dried meat of one animal case (goat) was positive by qPCR.
Conclusion: We report the first qPCR-confirmed outbreaks of anthrax in Ethiopia. Both outbreaks were controlled through active case finding, carcass management, ring vaccination of livestock, training of health professionals and outreach with livestock owners. Human and animal health authorities should work together using a One Health approach to improve case reporting and vaccine coverage.

22/07/2021

Anthrax
Anthrax, a highly infectious and fatal disease of mammals and humans, is caused by a relatively large spore-forming rectangular shaped bacterium called Bacillus anthracis.

Anthrax occurs on all the continents, causes acute mortality in ruminants and is a zoonosis. The bacteria produce extremely potent toxins which are responsible for the ill effects, causing a high mortality rate. While most mammals are susceptible, anthrax is typically a disease of ruminants and humans.

It does not typically spread from animal to animal nor from person to person. The bacteria produce spores on contact with oxygen.

Clinical Signs
Sudden death (often within 2 or 3 hours of being apparently normal) is by far the most common sign;
Very occasionally some animals may show trembling, a high temperature, difficulty breathing, collapse and convulsions before death. This usually occurs over a period of 24 hours;
After death blood may not clot, resulting in a small amount of bloody discharge from the nose, mouth and other openings/
Diagnosis
On the clinical signs described above;
Rod-shaped bacteria surrounded by a capsule are visible in blood smears made from surface blood vessels
Post-mortem examinations should not be undertaken on suspected anthrax cases (including any cow that has died suddenly for no apparent reason) until a blood smear has proved negative);
If a carcass is opened accidentally, the spleen is usually swollen and there is bloodstained fluid in all body cavities.
Treatment
Due to the rapidity of the disease treatment is seldom possible, although high doses of penicillin have been effective in the later stages of some outbreaks.

Prevention
Infection is usually acquired through the ingestion of contaminated soil, fodder or compound feed. Anthrax spores in the soil are very resistant and can cause disease when ingested even years after an outbreak. The spores are brought to the surface by wet weather, or by deep tilling, and when ingested or inhaled by ruminants the disease reappears.

Where an outbreak has occurred, carcases must be disposed of properly, the carcase should not be open (exposure to oxygen will allow the bacteria to form spores) and premises should be quarantined until all susceptible animals are vaccinated.

Vaccination in endemic areas is very important. Although vaccination will prevent outbreaks veterinary services sometimes fail to vaccinate when the disease has not appeared for several years. But because the spores survive for such lengthy periods, the risk is always present.

Anthrax is a disease listed in the World Organisation for Animal Health (OIE) Terrestrial Animal Health Code, 2011, (Article 1.2.3) and must be reported to the OIE (Chapter 1.1.2 – Notification of Diseases and Epidemiological Information).

22/07/2021

Anthrax is a zoonotic disease caused by the sporeforming bacterium Bacillus anthracis. Anthrax is most common in wild and domestic herbivores (eg, cattle, sheep, goats, camels, antelopes) but can also be seen in people exposed to tissue from infected animals, to contaminated animal products, or directly to B anthracis spores under certain conditions. Depending on the route of infection, host factors, and potentially strain-specific factors, anthrax can have several different clinical presentations. In herbivores, anthrax commonly presents as an acute septicemia with a high fatality rate, often accompanied by hemorrhagic lymphadenitis. In dogs, people, horses, and pigs, it is usually less acute although still potentially fatal.

B anthracis spores can remain viable in soil for many years. During this time, they are a potential source of infection for grazing livestock but generally do not represent a direct risk of infection for people. Grazing animals may become infected when they ingest sufficient quantities of these spores from the soil. In addition to direct transmission, biting flies may mechanically transmit B anthracis spores from one animal to another. The latter follows when there have been rains encouraging a high fly hatch and reporting has been delayed on the index ranch, such that there are 4–6 moribund or dead cattle for the flies to feed on. Feed contaminated with bone or other meal from infected animals can serve as a source of infection for livestock, as can hay muddy with contaminated soil. Raw or poorly cooked contaminated meat is a source of infection for zoo carnivores and omnivores; anthrax resulting from contaminated meat consumption has been reported in pigs, dogs, cats, mink, wild carnivores, and people.

Epidemiology:
Underdiagnosis and unreliable reporting make it difficult to estimate the true incidence of anthrax worldwide. However, anthrax has been reported from nearly every continent and is most common in agricultural regions with neutral or alkaline, calcareous soils. In these regions, anthrax periodically emerges as epizootics among susceptible domesticated and wild animals. These epizootics are usually associated with drought, flooding, or soil disturbance, and many years may pass between outbreaks. During interepidemic periods, sporadic cases may help maintain soil contamination. But it is now absent from some countries in western Europe, north Africa, and east of the Mississippi in the USA.

Human cases may follow contact with contaminated carcasses or animal products. The risk of human disease in these settings is comparatively small in developed countries, partly because people are relatively resistant to infection. However, in developing countries, each affected cow can result in up to 10 human cases because of home slaughter and sanitation issues. In cases of natural transmission, people exhibit primarily cutaneous disease (>95% of all cases). GI anthrax (including pharyngeal anthrax) may be seen among human populations after consumption of contaminated raw or undercooked meat. Under certain artificial conditions (eg, laboratories, animal hair processing facilities, exposure to weaponized spore products), people may develop a highly fatal form of disease known as inhalational anthrax or woolsorter’s disease. Inhalational anthrax is an acute hemorrhagic lymphadenitis of the mediastinal lymph nodes, often accompanied by hemorrhagic pleural effusions, severe septicemia, meningitis, and a high mortality rate. Of late, injection anthrax has emerged in conjunction with contaminated he**in.

The precise incidence of anthrax among animals in the USA is unknown. Throughout the past hundred years, animal infections have been seen in nearly all states, with highest frequency from the Midwest and West. Presently, anthrax is enzootic in west Texas and northwest Minnesota; sporadic in south Texas, Montana, eastern North and South Dakota; and only occasionally seen elsewhere. The annual incidence of human anthrax in the USA has declined from ~130 cases annually in the beginning of the last century to no reported cases in 2004–2005.

In addition to causing naturally occurring anthrax, B anthracis has been manufactured as a biologic warfare agent. B anthracis was used successfully as a weapon of terrorism in 2001, killing 5 people and causing disease in 22. Probably because of the method of delivery (via mail), no known animal disease resulted from this attack. Weaponized spores represent a threat to both human and animal populations. The World Health Organization has estimated that 50 kg of B anthracis released upwind of a population center of 500,000 could result in 95,000 deaths and 125,000 hospitalizations. The effect on animal populations has not been estimated, but because livestock are more susceptible to B anthracis infection than primates, the outcome of an aerosol attack with B anthracis spores against livestock would result in higher and earlier mortality and morbidity rates than among a human population. Subsequent to the 1979 Severdlovsk incident, human cases were seen up to 4 km from the source, but dead sheep were noted 64 km downwind, and in villages between.

Pathogenesis:
After wound inoculation, ingestion, or inhalation, spores infect macrophages, germinate, and proliferate. In cutaneous and GI infection, proliferation can occur at the site of infection and in the lymph nodes draining the site of infection. Lethal toxin and edema toxin are produced by B anthracis and respectively cause local necrosis and extensive edema, which are frequent characteristics of the disease. As the bacteria multiply in the lymph nodes, toxemia progresses and bacteremia may ensue. With the increase in toxin production, the potential for disseminated tissue destruction and organ failure increases. After vegetative bacilli are discharged from an animal after death (by carcass bloating, scavengers, or postmortem examination), the oxygen content of air induces sporulation. Spores are relatively resistant to extremes of temperature, chemical disinfection, and dessication. Necropsy is discouraged because of the potential for blood spillage and vegetative cells to be exposed to air, resulting in large numbers of spores being produced. Because of the rapid pH change after death and decomposition, vegetative cells in an unopened carcass quickly die without sporulating.

Clinical Findings:
Typically, the incubation period is 3–7 days (range 1−14 days). The clinical course ranges from peracute to chronic. The peracute form (common in cattle and sheep) is characterized by sudden onset and a rapidly fatal course. Staggering, dyspnea, trembling, collapse, a few convulsive movements, and death may occur in cattle, sheep, or goats with only a brief evidence of illness.

In acute anthrax of cattle and sheep, there is an abrupt fever and a period of excitement followed by depression, stupor, respiratory or cardiac distress, staggering, convulsions, and death. Often, the course of disease is so rapid that illness is not observed and animals are found dead. Body temperature may reach 107°F (41.5°C), rumination ceases, milk production is materially reduced, and pregnant animals may abort. There may be bloody discharges from the natural body openings. Some infections are characterized by localized, subcutaneous, edematous swelling that can be quite extensive. Areas most frequently involved are the ventral neck, thorax, and shoulders.

The disease in horses may be acute. Signs may include fever, chills, severe colic, anorexia, depression, weakness, bloody diarrhea, and swellings of the neck, sternum, lower abdomen, and external genitalia. Death usually occurs within 2–3 days of onset.

Although relatively resistant, pigs may develop an acute septicemia after ingestion of B anthracis, characterized by sudden death, oropharyngitis, or more usually a mild chronic form. Oropharyngeal anthrax is characterized by rapidly progressive swelling of the throat, which may cause death by suffocation. In the chronic form, pigs show systemic signs of illness and gradually recover with treatment. Some later show evidence of anthrax infection in the cervical lymph nodes and tonsils when slaughtered (as apparently healthy animals). Intestinal involvement is seldom recognized and has nonspecific clinical characteristics of anorexia, vomiting, diarrhea (sometimes bloody), or constipation.

In dogs, cats, and wild carnivores, the disease resembles that seen in pigs. In wild herbivorous animals, the expected course of illness and lesions varies by species but resembles, for the most part, anthrax in cattle.

Lesions:
Rigor mortis is frequently absent or incomplete. Dark blood may ooze from the mouth, nostrils, and a**s with marked bloating and rapid body decomposition. If the carcass is inadvertently opened, septicemic lesions are seen. The blood is dark and thickened and fails to clot readily. Hemorrhages of various sizes are common on the serosal surfaces of the abdomen and thorax as well as on the epicardium and endocardium. Edematous, red-tinged effusions commonly are present under the serosa of various organs, between skeletal muscle groups, and in the subcutis. Hemorrhages frequently occur along the GI tract mucosa, and ulcers, particularly over Peyer’s patches, may be present. An enlarged, dark red or black, soft, semifluid spleen is common. The liver, kidneys, and lymph nodes usually are congested and enlarged. Meningitis may be found if the skull is opened.

In pigs with chronic anthrax, the lesions usually are restricted to the tonsils, cervical lymph nodes, and surrounding tissues. The lymphatic tissues of the area are enlarged and are a mottled salmon to brick-red color on cut surface. Diphtheritic membranes or ulcers may be present over the surface of the tonsils. The area around involved lymphatic tissues generally is gelatinous and edematous. A chronic intestinal form involving the mesenteric lymph nodes is also recognized.

Diagnosis:
A diagnosis based on clinical signs alone is difficult. Confirmatory laboratory examination should be attempted if anthrax is suspected. Because the vegetative cell is not robust and will not survive 3 days in transit, the optimal sample is a cotton swab dipped in the blood and allowed to dry. This results in sporulation and the death of other bacteria and contaminants. For carcasses dead >3 days, either the nasal turbinates should be swabbed or turbinate samples removed. Pigs with localized disease are rarely bacteremic, so a small piece of affected lymphatic tissue that has been collected aseptically should be submitted. Before submission, the receiving reference laboratory should be contacted regarding appropriate specimen labelling, handling, and shipping procedures.

Specific diagnostic tests include bacterial culture, PCR tests, and fluorescent antibody stains to demonstrate the agent in blood films or tissues. Western blot and ELISA tests for antibody detection are available in some reference laboratories. Lacking other tests, fixed blood smears stained with Loeffler’s or MacFadean stains can be used and the capsule visualized; however, this can result in ~20% false positives.

Bacillus anthracis, methylene blue stain
Bacillus anthracis, methylene blue stain
COURTESY OF THE DEPARTMENT OF PATHOBIOLOGY, UNIVERSITY OF GUELPH.

Bacillus anthracis, medusa head morphology
Bacillus anthracis, medusa head morphology
COURTESY OF DR. J. GLENN SONGER.

Bacillus anthracis, ground glass colonies
Bacillus anthracis, ground glass colonies
COURTESY OF DR. J. GLENN SONGER.

In livestock, anthrax must be differentiated from other conditions that cause sudden death. In cattle and sheep, clostridial infections, bloat, and lightning strike (or any cause of sudden death) may be confused with anthrax. Also, acute leptospirosis, bacillary hemoglobinuria, anaplasmosis, and acute poisonings by bracken fern, sweet clover, and lead must be considered in cattle. In horses, acute infectious anemia, purpura, colic, lead poisoning, lightning strike, and sunstroke may resemble anthrax. In pigs, acute classical swine fever, African swine fever, and pharyngeal malignant edema are diagnostic considerations. In dogs, acute systemic infections and pharyngeal swellings due to other causes must be considered.

Treatment, Control, and Prevention:
Anthrax is controlled through vaccination programs, rapid detection and reporting, quarantine, treatment of asymptomatic animals (postexposure prophylaxis), and burning or burial of suspect and confirmed cases. In livestock, anthrax can be controlled largely by annual vaccination of all grazing animals in the endemic area and by implementation of control measures during epizootics. The nonencapsulated Sterne-strain vaccine is used almost universally for livestock immunization. Vaccination should be done at least 2–4 wk before the season when outbreaks may be expected. Because this is a live vaccine, antibiotics should not be administered within 1 wk of vaccination. Before vaccination of dairy cattle during an outbreak, all of the procedures required by local laws should be reviewed and followed. Human anthrax vaccines currently licensed and used in the USA and Europe are based on filtrates of artificially cultivated B anthracis.

Early treatment and vigorous implementation of a preventive program are essential to reduce losses among livestock. Livestock at risk should be immediately treated with a long-acting antibiotic to stop all potential incubating infections. This is followed by vaccination ~7–10 days after antibiotic treatment. Any animals becoming sick after initial treatment and/or vaccination should be retreated immediately and revaccinated a month later. Simultaneous use of antibiotics and vaccine is inappropriate, because available commercial vaccines for animals in the USA are live vaccines. Animals should be moved to another pasture away from where the bodies had lain and any possible soil contamination. Suspected contaminated feed should be immediately removed. Domestic livestock respond well to penicillin if treated in the early stages of the disease. Oxytetracycline given daily in divided doses also is effective. Other antibacterials, including amoxicillin, chloramphenicol, ciprofloxacin, doxycycline, erythromycin, gentamicin, streptomycin, and sulfonamides also can be used, but their effectiveness in comparison with penicillin and the tetracyclines has not been evaluated under field conditions.

In addition to therapy and immunization, specific control procedures are necessary to contain the disease and prevent its spread. These include the following: 1) notification of the appropriate regulatory officials; 2) rigid enforcement of quarantine (after vaccination, 2 wk before movement off the farm, 6 wk if going to slaughter); 3) prompt disposal of dead animals, manure, bedding, or other contaminated material by cremation (preferable) or deep burial; 4) isolation of sick animals and removal of well animals from the contaminated areas; 5) cleaning and disinfection of stables, pens, milking barns, and equipment used on livestock; 6) use of insect repellents; 7) control of scavengers that feed on animals dead from the disease; and 8) observation of general sanitary procedures by people who handle diseased animals, both for their own safety and to prevent spread of disease. Contaminated soils are very difficult to completely decontaminate, but formaldehyde will be successful if the level is not excessive. The process generally requires removal of soil.

Human infection is controlled through reducing infection in livestock, veterinary supervision of animal production and slaughter to reduce human contact with potentially infected livestock or animal products, and in some settings either pre- or postexposure prophylaxis. In countries where anthrax is common and vaccination coverage in livestock is low, people should avoid contact with livestock and animal products that were not inspected before and after slaughter. In general, consumption of meat from animals that have exhibited sudden death, meat obtained via emergency slaughter, and meat of uncertain origin should be avoided. Routine vaccination against anthrax is indicated for individuals engaged in work involving large quantities or concentrations of B anthracis cultures or activities with a high potential for aerosol production. Laboratory workers using standard Biosafety Level 2 practices in the routine processing of clinical samples are not at increased risk of exposure to B anthracis spores. The risk for workers who come into contact with imported animal hides, furs, bone meal, wool, animal hair, or bristles has been reduced by improvements in industry standards and import restrictions. Routine preexposure vaccination is recommended for people in this group only when these standards and restrictions are insufficient to prevent exposure to anthrax spores. Routine vaccination of veterinarians in the USA is not recommended because of the low incidence of animal cases. However, vaccination may be indicated for veterinarians and other high-risk individuals handling potentially infected animals in areas where there is a high incidence of anthrax cases.

The CDC has recommended that those at risk of repeated exposure to B anthracis spores in response to a bioterrorism attack should be vaccinated. Those groups include some emergency first responders, federal responders, and laboratory workers. Vaccination in anticipation of a terrorist attack is not recommended for other populations.

For people, postexposure prophylaxis against B anthracis is recommended after an aerosol exposure to B anthracis spores. Prophylaxis may consist of antibiotic therapy alone or the combination of antibiotic therapy and vaccination, if vaccine is available (most human vaccines are not live). Although there is no approved regimen, the CDC has suggested that antibiotics may be discontinued after three doses of vaccine have been administered according to the standard schedule (0, 2, and 4 wk). Because of availability and ease of dosing, doxycycline or ciprofloxacin may be chosen initially for antibiotic chemoprophylaxis until the susceptibility of the infecting organism is determined. Penicillin and doxycycline are approved by the FDA for treatment of anthrax in people and have traditionally been considered the drugs of choice. Both ciprofloxacin and ofloxacin have demonstrated in vitro activity against B anthracis. Although naturally occurring B anthracis resistance to penicillin is infrequent, it is reported; resistance to other antibiotics has been noted. Antibiotics are effective against the germinated form of B anthracis but are not effective against the spore form of the organism. Spores may survive in the mediastinal lymph nodes in the lungs for months without germination in nonhuman primates.

There are currently no approved vaccination regimens for postexposure prophylaxis after B anthracis exposures. Although postexposure chemoprophylaxis using antibiotics alone has been effective in animal models, the definitive length of treatment remains unclear. Antibiotic chemoprophylaxis may be switched to penicillin VK or amoxicillin in children or pregnant women once antibiotic susceptibilities are known and the organism is found to be susceptible to penicillin. The safety and efficacy of anthrax vaccine in children or pregnant women has not been studied; therefore, a recommendation for use of vaccine in these groups cannot be made. Although the shortened vaccine regimen has been effective when used in a postexposure regimen that includes antibiotics, the duration of protection from vaccination is not known. The existing evidence suggests that vaccine protection is adequate for 12 mo. If subsequent exposures occur, additional vaccinations may be required.

There are no definitive recommendations for postexposure prophylaxis after cutaneous or GI exposures of people to B anthracis. Based on the slow progression of disease, low fatality rate, and ease of antibiotic treatment of cutaneous anthrax, and the general low risk of cutaneous disease after natural exposure, postexposure prophylaxis is not recommended after direct cutaneous exposure to contaminated animals or animal products. However, immediate washing of the exposed areas is advised. Those exposed should be advised of the signs of cutaneous anthrax (ie, an inflamed but painless area with or without circumferential small vesicles, enlargement of the regional lymph nodes) and should seek medical assistance if illness develops. Because of the high fatality rate and rapid progression of GI anthrax, serious consideration should be given to initiating postexposure antibiotic prophylaxis for those who consume contaminated undercooked or raw meat. There is no current indication for vaccination after either cutaneous exposure or ingestion.

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Treatment Due to the rapidity of the disease treatment is seldom possible, although high doses of penicillin have been effective in the later stages of some outbreaks. Prevention Infection is usually acquired through the ingestion of contaminated soil, fodder or compound feed. Anthrax spores in the soil are very resistant and can cause disease when ingested even years after an outbreak. The spores are brought to the surface by wet weather, or by deep tilling, and when ingested or inhaled by ruminants the disease reappears. Where an outbreak has occurred, carcases must be disposed of properly, the carcase should not be open (exposure to oxygen will allow the bacteria to form spores) and premises should be quarantined until all susceptible animals are vaccinated. Vaccination in endemic areas is very important. Although vaccination will prevent outbreaks veterinary services sometimes fail to vaccinate when the disease has not appeared for several years. But because the spores survive for such lengthy periods, the risk is always present. Anthrax is a disease listed in the World Organisation for Animal Health (OIE) Terrestrial Animal Health Code, 2011, (Article 1.2.3) and must be reported to the OIE (Chapter 1.1.2 – Notification of Diseases and Epidemiological Information).

Causes It is very rare that people get anthrax infection through natural causes. However, anthrax can be produced in laboratories and may be used as an agent of biological warfare. Anthrax is used in this manner because of the serious disease that results when the anthrax spores are inhaled. Inhaled anthrax often causes death if it's not treated in the early stages, which is why it is very important to recognize the symptoms of this infection (see "Symptoms and Complications"). The most common type of anthrax infection is cutaneous (on the skin) anthrax. In fact, this accounts for over 95% of naturally-occurring anthrax infections. Cutaneous anthrax infection may take place when someone handles animals or animal products (wool or other woven materials) that are contaminated with anthrax, or if someone handles materials that have been intentionally contaminated with anthrax. It is quite rare for meat to be contaminated with the bacteria that causes anthrax in North America. Therefore, intestinal anthrax is very rare on this continent.

Making the Diagnosis Anthrax is diagnosed by taking samples from blood, respiratory secretion, or from any skin sores. The samples are sent to a laboratory to determine if they contain the bacteria that cause anthrax. The results are usually available about 2 days after the sample is taken. Blood tests can determine if a person has come in contact with the bacteria that cause anthrax. Antibodies (proteins that fight off substances the body sees as foreign) to the bacteria will have been produced by the body's immune system, and they can be detected by a laboratory test. People can be exposed to the bacteria that cause anthrax without becoming sick. Your doctor will evaluate your risk of exposure. However, if a test comes back positive, that person should be treated for anthrax in case the infection is in the early stages, before symptoms are evident.

Anthrax disease occurrence Anthrax is considered endemic in livestock in Georgia. In 2007, the annual vaccination became the responsibility of livestock owners, while contracting of private veterinarians was not officially required. Six years later, due to increase in human outbreaks associated with livestock handling, there is a need to find out the risk factors of livestock anthrax in Georgia. Anthrax is a zoonotic infection caused by the gram-positive rod Bacillus anthracis. Most cases of anthrax are cutaneous (95%); the remaining cases are inhalational (5%) and gastrointestinal (< 1%). Anthrax caused by inhalation is usually fatal, and symptoms usually begin days after exposure. Bioterrorism must be suspected in any case of inhalational anthrax.

Anthrax is a bacterial disease caused by the spore– forming Bacillus anthracis, a Gram-positive, rod-shaped bacterium the only obligate pathogen in the large genus Bacillus. 2.1.1. Cycle of infection When conditions are not conducive to growth and multiplication of the vegetative forms of B. anthracis, they start to form spores. Sporulation requires the presence of free oxygen. In the natural situation, this means the vegetative cycles occur within the low oxygen environment of the infected host and, within the host, the organism is exclusively in the vegetative form. Once outside the host, sporulation commences upon exposure to the air and the spore forms are essentially the exclusive phase in the environment. It is very largely through the uptake of spores from the environment that anthrax is contracted. The cycle of infection is illustrated in Fig. 1. Within the infected host the spores germinate to produce the vegetative forms which multiply, eventually killing the host (see chapter 5). A proportion of the bacilli released by the dying or dead animal into the environment (usually soil under the carcass) sporulate, ready to be taken up by another animal. This uptake by the next host may happen at any time, from less than one hour to many decades later. Cycle of infection in anthrax. The spore is central to the cycle, although vegetative forms may also play a role in establishing infection when, for example, humans or carnivores eat meat from an animal that died of anthrax or when biting flies transmit

Anthrax disease treatment and vaccination

Because anthrax is a soil borne disease, beef cattle and bison are most likely to contract the disease because they graze lower to the ground than many other herbivores, particularly in drought conditions or overgrazed pastures. It is also believed that the abrasive forages they consume can injure the mouth and allow the bacteria quick access to the blood stream. Three types of anthrax: Gastrointestinal: Caused when bacteria spores from an infected animal are ingested. The most common cause of anthrax in beef cattle. Cutaneous: Contracted via a skin wound. The most common way that anthrax is contracted by people. Pulmonary: Caused when the bacteria are inhaled. This type is the most dangerous, but is virtually impossible for animals to contract under natural conditions. This type of anthrax occurs in rare situations where people are working directly with contaminated hides. When an animal dies of anthrax, the bacteria is present in most tissues of the body. If the tissues are not exposed to oxygen, the bacteria cannot form the spores that infect other animals, and quickly die off. However, in most cases scavengers or carnivores open the carcass soon after death. This exposes the bacteria to oxygen, allowing infectious spores to form. Spores are tough, ‘egg-like’ microscopic structures that are difficult to destroy and can survive for decades. Spores continue to live in the soil long after the animal has decomposed, especially in alkaline (non-acidic) soils. Anthrax spores end up deep in the soil and are brought to the surface when the ground is disturbed, for example by: digging (wells, ditches, pipelines, etc.), heavy rains, deep tilling, overcrowded or overgrazed areas, or soil erosion (e.g. wind, water, or wallows). The spores brought to the surface can easily be ingested by cattle while grazing and cause infection. Spores concentrate in low spots when floodwaters evaporate and infect cattle that drink standing water. During droughts, animals graze closer t

Anthrax disease Anthrax is a disease that affects humans and animals. In Ethiopia, anthrax is a reportable disease and assumed to be endemic, although laboratory confirmation has not been routinely performed until recently. We describe the findings from the investigation of two outbreaks in Amhara region. Methods: Following reports of suspected outbreaks in Wag Hamra zone (Outbreak 1) and South Gondar zone (Outbreak 2), multi-sectoral teams involving both animal and public health officials were deployed to investigate and establish control programs. A suspect case was defined as: sudden death with rapid bloating or bleeding from orifice(s) with unclotted blood (animals); and signs compatible with cutaneous, ingestion, or inhalation anthrax ≤7 days after exposure to a suspect animal (humans). Suspect human cases were interviewed using a standard questionnaire. Samples were collected from humans with suspected anthrax (Outbreak 1 and Outbreak 2) as well as dried meat of suspect animal cases (Outbreak 2). A case was confirmed if a positive test was returned using real-time polymerase chain reaction (qPCR). Results: In Outbreak 1, a total of 49 cows died due to suspected anthrax and 22 humans developed symptoms consistent with cutaneous anthrax (40% attack rate), two of whom died due to suspected ingestion anthrax. Three people were confirmed to have anthrax by qPCR. In Outbreak 2, anthrax was suspected to have caused the deaths of two livestock animals and one human. Subsequent investigation revealed 18 suspected cases of cutaneous anthrax in humans (27% attack rate). None of the 12 human samples collected tested positive, however, a swab taken from the dried meat of one animal case (goat) was positive by qPCR. Conclusion: We report the first qPCR-confirmed outbreaks of anthrax in Ethiopia. Both outbreaks were controlled through active case finding, carcass management, ring vaccination of livestock, training of health professionals and outreach with livestock owners