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Handling, sale of diseased cow carcasses led to 2010 anthrax outbreak in Bhutan
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A 2010 outbreak of Bacillus anthracis among humans was traced to grazing farm animals in the Himalayan nation of Bhutan in South Asia, according recent study findings.
As a result, researchers are recommending comprehensive preparedness and response guidelines to increase public awareness of anthrax in that country.
In the study, a research team investigated an outbreak of B. anthracis among animals in Kaktong, a village in the Zhemgang district of Bhutan, which subsequently spread to humans in eight nearby villages. The outbreak was thought to be attributable to heavy rain, which may have led to the emergence of B. anthracis spores to the surface of the soil and eaten by grazing animals.
Suspected anthrax was defined as signs or symptoms of infection in an animal, including sudden death, bloated carcass or bleeding of unclotted blood. Further samples were collected from animals with positive blood smears and taken to the CDC in Atlanta for culture and characterization of isolates. In three of the samples (two ear tips and one nasal swab) from three cattle in three separate villages, the researchers isolated B. anthracis.
The Bhutan isolates were determined to belong to the B1 lineage (genotype 83) and the single nucleotide polymorphism subgroup B.Br.001/002. The B1 lineage is primarily associated with South Africa, but it has been reported in parts of the United States, Europe and Asia.
The research team investigated the means of transmission among the animals and humans in affected areas and instituted control efforts. They reported that in the site of the initial cases, in Kaktong, a cow died suddenly after brief illness, and this animal had a bloated carcass and bleeding of unclotted blood from nasal orifices. The owner of this cow dressed the meat of the animal and sold or shared it for human consumption throughout the village. Infected meat transport led to disease transmission and death in herds of animals in eight other villages; similarly, the carcasses of these animals were dressed and sold for human consumption. Horses used to carry the infected meat also became infected with B. anthracis and died of the disease. Overall, during the period spanning from July to September 2010, 43 animals in nine villages succumbed to the disease.
The researchers also found that within a week of exposure to the diseased carcasses, nine humans who handled and dressed the mean developed black eschar skin lesions, which are characteristic of anthrax. These cutaneous lesions appeared on the patients’ necks, fingers, arms, feet and cheeks. Of the nine individuals infected with cutaneous anthrax, one died.
According to the researchers, such exposure to and dissemination of diseased animal carcasses promotes zoonotic transmission of the disease and should be the focus of increased awareness efforts in Bhutan.
“From this outbreak investigation and our experiences in Bhutan, we recommend the following measures for this country: development of comprehensive guidelines for anthrax surveillance among humans and animals; establishment of surveillance for anthrax hot-spot areas; and development of education programs to teach persons at high risk about anthrax transmission, the care of skin abrasions, and disease-prevention measures, including personal hygiene practices and refusal to eat meat from dead or sick animals,” the researchers wrote.
Disclosure: The researchers report no relevant financial disclosures.
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