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

208 BACTERIOSESFrom 1958 to 1979, 46,937 cases of human plague were recorded in 30 countries;if Vietnam is excluded, the total number is reduced to 15,785. The large number ofcases in Vietnam is attributed to military operations there and consequent ecologicchanges. On the other hand, 16 of the 30 countries reporting plague cases were inAfrica. However, incidence of the disease on that continent was very low, less than6% of the world total (Akiev, 1982). Figure 14 shows the number of cases anddeaths caused by human plague worldwide from 1971 to 1980.The incidence of plague from 1977 to 1991 included 14,752 cases with 1,391deaths distributed in 21 countries (WHO, 1993).In 1991, there was a large increase of cases in Africa, with a total of 1,719 peopleaffected, due primarily to an outbreak in Tanzania. In that country, there were 60deaths among a total of 1,293 cases, 1,060 of which occurred in the Tanga region.There were also 137 cases reported in Madagascar and 289 in Zaire (WHO, 1993).In Asia, there were 226 total cases, with 15 deaths. There were 100 cases inMyanmar, 94 in Vietnam, 29 in China (with 11 deaths), and the remainder in twoother countries (WHO, 1993).There are seven countries in the Americas with cases of plague: Bolivia, Brazil,Ecuador, Peru, the US, and occasionally, Colombia and Venezuela (Akiev, 1982).During the period 1971–1980, there were 2,312 cases in the Americas (Table 2),1,551 of which occurred in Brazil, 316 in Peru, 247 in Bolivia, 123 in the US, and75 in Ecuador (PAHO, 1981). In all the countries, the number of cases fluctuatedgreatly from year to year; at times, epidemic outbreaks have occurred. Plague continuesto be a public health problem in the Americas because of the persistence ofsylvatic plague and the link between domestic and wild rodents. In Ecuador, an outbreakof seven cases occurred in May 1976 in Nizac, Chimborazo Province, a settlementof 850 inhabitants. The outbreak was preceded by a large epizootic in ratsand mortality among guinea pigs raised in homes for food. The worst outbreak since1966 occurred in 1984 in northern Peru, with 289 cases reported in 40 localities. Anassociation was presumed between this outbreak and a great abundance of rodents,possibly the result of ecologic changes due to flooding (Rust, 1985).In the US, 35 cases were recorded from April to August 1983, the greatest numberof cases since 1925. Almost all the cases occurred in five southwestern states.Twenty-one cases of plague were reported in the Americas in 1991. Ten of theseoccurred in Brazil and 11 in the US, although there were no deaths (WHO, 1993).In 1992, there were 8 cases in Brazil (all in Bahia) and 13 in the US (4 in Arizona,4 in New Mexico, and 1 each in five more states) (OPS, 1992). One of the cases inArizona was primary pulmonary plague in a 31-year-old patient who died one dayafter being admitted to the hospital. Blood and urine cultures taken from the patientwere negative. After the patient’s death, Y. pestis was isolated from the sputum. Thesource of the infection was a sick cat. This is the third case in the US of primary pulmonaryplague contracted from a cat. The incubation period is very short in thesecases (two to three days) and the symptoms do not lead one to suspect plague (CDC,1992). There have been no cases of direct human-to-human transmission in the USsince 1924 (Benenson, 1990).In October 1992, an outbreak of plague was reported in Cajamarca (Peru) whichis still active. In nine localities affected, with an estimated at-risk population of30,000, there were 547 cases and 19 deaths (up to mid-January 1994). The outbreakswere preceded by deaths among wild rodents and guinea pigs (Cavia porcellus) bred