Five countries in eastern and southern Africa have been affected by the anthrax epidemic, and this year there have been more than 1.100 cases of possible illness from the disease, as well as 20 deaths, the World Health Organization said.
In Kenya, Malawi, Uganda, Zambia and Zimbabwe, 1.166 cases of anthrax have been reported.
The WHO announced that 37 deaths from anthrax have been laboratory confirmed.
Five countries have seasonal anthrax outbreaks every year, but Zambia is experiencing its worst since 2011. Malawi reported its first case of the disease this year, and Uganda - 13 deaths.
Anthrax usually affects livestock such as cattle, sheep and goats, as well as wild herbivores.
Humans can become infected through animals and contaminated animal products.
Anthrax is generally not considered contagious between people, although there have been rare cases of person-to-person transmission, the WHO says. It is caused by spore-forming bacteria and is sometimes associated with the biological weapon version.
Such anthrax attacks in the United States in 2001, when five people died and 17 became ill after being exposed to anthrax spores from letters sent in the mail.
Anthrax bacteria also occur naturally in soil.
In a separate assessment of the most worrying outbreak in Zambia, the WHO said 20 suspected cases - with four deaths - had been reported there as of November 684.
Human cases of anthrax have been reported in nine of Zambia's 10 provinces. 26 people are thought to have become infected by eating contaminated hippo meat.
The WHO said there was a high risk of Zambia's epidemic spreading to neighboring countries.
The outbreaks in all five countries "are likely to have been triggered by multiple factors, including climate shocks, insecure food distribution, the perception of low risk of infection when handling meat from infected animals," the WHO said.
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