For the past several months, Zambia has been combating another anthrax outbreak. A prior outbreak occurred in the province of Muchinga in late September of 2016, but was brought under control by mid-October. During the outbreak, a total of 44 people were infected. Fortunately, no deaths were reported. All cases were reported to have become infected after eating contaminated meat.
In this recent outbreak, 67 people are reported to have contracted anthrax in the Western province, and two people have died. This outbreak began in November of 2016 and has persisted throughout January and has now continued into February. Five districts have reportedly been affected in the Western province: Limulunga, Nalolo, Kalabo, Shangombo and Sioma. In addition to human infections, 40 animals died from anthrax poisoning during the first week of January alone.
Anthrax is most commonly found in agricultural regions of Central and South America, sub-Saharan Africa, central and southwestern Asia, southern and eastern Europe, and the Caribbean. Animals ingest or inhale the bacteria Bacillus anthracis that is found naturally in soil. Once the bacteria enter the body, it becomes active and begins to multiply and produce toxins that are harmful to the animal, leading to severe illness and often death. The bacteria poses a significant threat to animals because Bacillus anthracis spores can remain in the soil for many years.
There are four types of anthrax that affect humans. Cutaneous anthrax occurs when anthrax spores get into the skin through a cut or scrape. This type of infection most commonly occurs in people handling infected animals or contaminated animal products. This is the most common form of the disease as well as the least severe. Symptoms usually occur one to seven days after exposure. A group of small blisters or bumps usually appear, and result in a sore around the infected area with a black centre. With treatment, almost all patients survive. Without treatment, 20% of cases may die.
Inhalation anthrax infection occurs when someone breathes in anthrax spores. People run the risk of inhaling spores mainly through occupational exposure, such as working in a slaughterhouse or tannery if an infected animal is present. Infection develops anywhere from a week to two months after exposure. The anthrax spores first infect the lymph nodes in the chest, and then spread through the body. Symptoms include fever and chills, nausea and vomiting, headache and sweats. This continues and leads to severe breathing problems and shock. With aggressive treatment, about 55% of people will survive. Without treatment, there is an 85-90% chance of death.
Gastrointestinal anthrax occurs when someone eats raw or undercooked meat from an infected animal. The spores mainly affect the throat, oesophagus, stomach, and intestines. Symptoms present themselves within one to seven days after exposure. The symptoms are very similar to inhalation anthrax, but also include symptoms like sore throat and hoarseness. Over 50% of people with gastrointestinal anthrax will die without treatment, but with treatment, 60% of patients survive.
Injection anthrax has been identified in injection drug users in northern Europe. It presents symptoms similar to a cutaneous anthrax infection, but may result in a deeper infection at the site of injection.
As of 11 January, a total of 17 cases in the Western Province outbreak. This total has since risen to 67 suspected cases and two deaths. Health officials are urging people to vaccinate their animals and caution people to avoid eating meat that may be infected.
In an attempt to control the outbreak, the Ministry of Fisheries and Livestock has launched a mass vaccination campaign for susceptible livestock, and the government has restricted the movement of cattle from affected areas to allow for their vaccination. A reported 65,000 herds of cattle are at risk of infection within the Western province. The main mode of human transmission in this outbreak has been through gastrointestinal anthrax infections, so the Ministry of Health is urging the public to refrain from eating meat from cattle that are suspected of being contaminated. This outbreak is proving to be on a greater scale than the outbreak that occurred in September and October, so public health officials must act accordingly to effectively control the outbreak.