zoonoses and communicable diseases common to ... - PAHO/WHO

ANTHRAX 23tive through culture and inoculation of laboratory animals. Of 35 cows, 42.9%were positive, and of 70 bulls, 14.3% were positive. The milk from 43 cows and 8sheep was also examined; 15 and 2 of the samples, respectively, were positive(Okolo, 1988).Some outbreaks and occasional cases of human infection have also been reportedin industrialized countries, such as the US (Hunter et al., 1989).In Africa, wildlife reserves periodically suffer great losses, especially among herbivores.A thesis presented at the University of Nairobi, Kenya, estimated thatanthrax accounts for about 11% of the mortality in the animal population each year,excluding calves. At Etosha National Park in Namibia, anthrax caused the death of1,635 wild animals of 10 species, or 54% of total mortality between January 1966and June 1974. The source of infection was artificial ponds (Ebedes, 1976). An outbreakoccurred on a reserve in Zambia between June and November of 1987, with atotal loss of over 4,000 animals. The victims were primarily hippopotamuses(Hippopotamus amphibius). Other species, such as the Cape buffalo (Syncerus caffer)and the elephant (Loxodonta africana), also seem to have been affected(Turnbull et al., 1991).The Disease in Man: The incubation period is from two to five days. Three clinicalforms are recognized: cutaneous, pulmonary or respiratory, and gastrointestinal.The cutaneous form is the most common and is contracted by contact withinfected animals (usually carcasses) or contaminated wool, hides, and fur. Theexposed part of the skin begins to itch and a papule appears at the inoculation site.This papule becomes a vesicle and then evolves into a depressed, black eschar.Generally, the cutaneous lesion is not painful or is only slightly so; consequently,some patients do not consult a doctor in time. If left untreated, the infection can leadto septicemia and death. The case fatality rate for untreated anthrax is estimated atbetween 5% to 20%.The pulmonary form is contracted by inhalation of B. anthracis spores. Atthe onset of illness, the symptomatology is mild and resembles that of a commonupper respiratory tract infection. Thus, many patients do not see a doctor in the earlystage of the disease when it would be easily cured. Some three to five days later thesymptoms become acute, with fever, shock, and resultant death. The case fatalityrate is high.Gastrointestinal anthrax is contracted by ingesting meat from infected animalsand is manifested by violent gastroenteritis with vomiting and bloody stools.Mortality ranges from 25% to 75% (Brachman, 1984).The recommended treatment for cutaneous anthrax is intramuscular administrationof 1 million units of procaine penicillin every 12 to 24 hours for five to sevendays. In the case of serious illness, as in pulmonary anthrax, the recommendation is2 million units of penicillin G per day administered intravenously or 500,000 unitsadministered intravenously through a slow drip every four to six hours until temperaturereturns to normal. Streptomycin, in 1 g to 2 g doses per day, has a synergisticeffect if administered at the same time as penicillin. Some penicillin-resistantstrains of B. anthracis have been found (Braderic and Punda-Polic, 1992). Penicillinsterilizes the organism in a short time, even in a single day in patients suffering fromcutaneous anthrax, but it should be borne in mind that the toxin remains and thepatient is still not cured.