Anthrax Outbreaks Reported in Five African Countries

More than 20 anthrax-related deaths have been reported in five countries in Africa since the start of 2023.

As of December 11, 2023, a total of 1,166 suspected and 37 confirmed cases have been recorded in Kenya, Malawi, Uganda, Zambia, and Zimbabwe, according to data reported to the World Health Organization (WHO).

Of the five countries, Zambia is witnessing its largest anthrax outbreak since 2011, with 25 confirmed cases and four deaths. Only sporadic cases have previously been reported in animals and humans in the country.

Over 400,000 vaccine doses have been earmarked for high-risk districts in Zambia's western province.

Annually, human anthrax infections are the highest in Africa, the Middle East, and Central and South Asia, says the WHO

"To end these outbreaks, we must break the infection cycle by first preventing animal disease. We are supporting the ongoing national outbreak control efforts by providing expertise as well as reinforcing collaboration with partner agencies for a common approach to safeguard human and animal health," said Dr Matshidiso Moeti, WHO Regional Director for Africa, in a press release.

Humans become infected with anthrax, a zoonotic disease, through contact with disease carrying animal carcasses or exposure to contaminated animal products. Rare person-to-person transmissions have been reported with cutaneous anthrax, which accounts for more than 95% of human cases worldwide.

Cutaneous anthrax usually develops 1–7 days after exposure, but incubation periods up to 17 days have been reported.

A study published by the journal Nature Biology estimated that 1.83 billion people (95% credible interval (CI): 0.59–4.16 billion) live within regions of anthrax risk, but most of that population faces little occupational exposure. 

Individuals potentially exposed to anthrax spores may be provided with prophylactic treatment. Anthrax responds well to antibiotics, says the WHO.

In the United States, Emergent BioSolutions Inc.'s CYFENDUS™ (Anthrax Vaccine Adsorbed, Adjuvanted) was approved on July 20, 2023, as a two-dose anthrax vaccine for Post-Exposure Prophylaxis use.

However, the U.S. CDC says vaccination against anthrax is not recommended for travelers and is not available for civilian travelers.