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Anthrax: An ancient threat



Anthrax kills animals and people. It threatens agricultural livelihoods. It is one of many diseases that have been doing so for centuries

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A veterinarian in Mali prepares for a cattle vaccination. (FAO/11002/J. Van Acker)

Until recently, few people unconnected with agriculture had heard of anthrax. But it is a serious livestock disease that can affect all warm-blooded animals and a particular threat to cattle and small ruminants like sheep and goats. It is zoonotic, meaning that it can affect humans. It is an ancient disease and may have caused plagues in ancient history. Treatment is possible with early diagnosis but often there are no symptoms and the animal dies swiftly and mysteriously.

The extent of anthrax is unclear, and its incidence in livestock is in fact declining. But the economic damage it does is not as significant as diseases such as foot-and-mouth.

Forty-eight countries had confirmed cases of animal anthrax in 2000. Of those, 36 were developing nations, and a further six or seven were transition economies. It is also endemic in certain parts of the United States, in particular Texas, where 11 ranches had confirmed cases in livestock or deer between January and August 2001. Cases were also reported in 2000 in Germany and France. But this is not, in the main, a disease of wealthy countries.

Animal anthrax outbreaks are frequently associated with conflict -- about a third of the affected countries were undergoing conflict or bordered those that were, including Afghanistan and neighbouring Tajikistan. Joint FAO/World Food Programme missions in 2001 found that anthrax had made inroads in both countries. Afghani pastoralists told the mission that they could not afford animal anthrax vaccines costing less than one US cent per dose.

"Refugees can spread diseases -- not just anthrax -- if they bring their livestock with them, either because they were infected to start with or they became infected in transit," says William Amanfu, veterinary bacteriologist of FAO's Animal Health Service. "Or they might bring their animals into an area where the disease exists but hasn't hitherto been reported. Also, conflict disrupts veterinary and disease control activities." The World Health Organization has noted that incidence of human anthrax is also higher in conflict zones.

Anthrax incidence also has a link with poverty. It is the poor who are more likely to consume a dead animal that probably died of the disease and who stand the greater chance of consuming uninspected meat from an animal suffering from anthrax before slaughter. It is poor countries with weak veterinary services that are likely to suffer frequent anthrax outbreaks.

Because of soil and climatic factors that contribute to the spread of anthrax, it is unlikely that it will be eliminated, despite the existence of an effective vaccine. "It's better to talk about limiting its economic impact, especially among the poor and the displaced, through preventive measures and public education," says Dr Amanfu.

Although FAO is concerned about animal anthrax, highly contagious diseases such as foot-and-mouth disease, rinderpest, contagious bovine pleuropneumonia of cattle and peste des petits ruminants (PPR) of sheep and goats tend to get more attention because of their greater impact on food security and implications for the poor.

From animals to people

 

A cow is examined at a slaughterhouse in Uruguay. (FAO/19800/R. Faidutti)

"Zoonoses -- diseases that spread from animals to humans -- are a big problem," says Dr Amanfu. "I think there should be better reporting of anthrax and more preventive measures adopted because of the zoonotic nature of the disease." FAO believes that better veterinary services can help control zoonoses in general, such as brucellosis and bovine tuberculosis, he adds, and fighting anthrax is one aspect of that package.

Anthrax can spread from animals to people, but not easily. The lethal form, pulmonary or inhalation anthrax, normally affects people working with wool or leather from diseased animals, and it is rare. At least 95 percent of human cases are cutaneous anthrax, affecting the skin, which is not so dangerous. With treatment, less than 1 percent of these end in death. A third type is gastric anthrax, contracted from eating the meat of an infected animal. Although not as dangerous as pulmonary anthrax, it can kill.

Human anthrax cases reported by the World Health Organization include a 1997 outbreak in Ghana that caused 185 cases and 26 deaths. Russia had three outbreaks in 1998, with 15 clinical cases and 2 deaths. Both deaths seemed related to butchering and consumption of contaminated meat. More recently, human anthrax has been found in pastoralists in Ethiopia. There are occasional serious outbreaks from consumption of infected wild animals such as hippopotamus. Even so, estimates suggest that there is only one gastric case for every 30-60 infected carcasses eaten.

Fighting diseases in the field
To aid in the fight against animal diseases, FAO provides vaccines and drugs, among other items, in emergencies -- for example to flood-affected farmers in Bangladesh. In the Horn of Africa and elsewhere, FAO has also helped control outbreaks of Rift Valley Fever, a mosquito-borne disease that can be fatal in humans, who show flu-like symptoms. In South America, FAO's work has included monitoring brucellosis. There have been many other projects aimed at zoonoses and at animal diseases in general.

Other FAO contributions to animal health include EMPRES, the Emergency Prevention System for Transboundary Animal and Plant Pests and Diseases. Founded in 1994, this programme strengthens local capacities to detect and deal with diseases that can cross borders. FAO also coordinates a disease surveillance network in 29 countries in Africa and the Middle East, the Regional Animal Disease Surveillance and Control Network. This network, which works in tandem with EMPRES, is funded by the International Fund for Agricultural Development (IFAD).

Both help establish national and transnational surveillance systems that work to eliminate animal diseases -- a major part of FAO's drive for food security.

13 November 2001

 

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