EXPLAINER:: What To Know as Deadly Anthrax Breaks Out In Nigeria’s Northwest State

On Tuesday, the Nigerian Ministry of Livestock Development alerted Nigerians over the outbreak of anthrax in Zamfara State

The Director of the Information and Public Relations Department of the ministry, Ben Bem Goong, said the Federal Ministry of Livestock Development wishes to officially notify the public of a confirmed outbreak of anthrax in a farm in Zamfara State.

What is anthrax?

Anthrax is a disease caused by the spore-forming bacteria Bacillus anthracis. The name of the bacteria derives from the Greek word for coal because of the ulcers with dark centers that develop on the skin of affected people.

Anthrax occurs on all continents and commonly causes high mortality, primarily in domestic and wild herbivores as well as most mammals and several bird species.

It is a serious zoonosis, meaning that it can be transmitted from animals to humans.

The bacteria produce extremely potent toxins, which are responsible for the ill effects. Anthrax spores are extremely resistant and can survive in the environment for decades, making the control or eradication of the disease very difficult.

Transmission and spread

Anthrax typically does not spread from animal to animal nor from person to person.

The bacteria produce spores in 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 feed.

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 by 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 of anthrax is rare in nature, anthrax spores have been developed and used as a biological weapon. 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 have been ill. In this acute form, there may be high fever, muscle tremors, and difficulty breathing seen shortly before the animal collapses and dies. Unclotted blood may exude from body openings and the body may not stiffen after death. The subacute form may be accompanied by progressive fever, depression, inappetence, weakness, prostration, and death.

In horses and (on occasion) in ruminants,, there may be digestive upsets and colic, fever, depressio,n, 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).

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.