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

266 BACTERIOSESArgentina and Brazil. In 1987, it was estimated that 1,680,000 cases and 1,030,000deaths occurred worldwide. In 1973, 60% to 90% of cases occurred in newbornsduring the first month of life (Orenstein and Wassilak, 1991). Currently, the distributionof the disease by age group is completely different in the US. In the period1989–1990, there were 117 cases of tetanus in 34 states, with an annual incidenceof 0.02 per 100,000 inhabitants. In marked contrast to developing countries, 58% ofthe patients were 60 years of age or older and only one case occurred in a newborn.Case fatality bore a direct relationship to age: 17% in patients aged 40 to 49, and50% in those aged 80 or older (CDC, 1993).Inhabitants of rural areas are more exposed than those in urban areas. Case fatalityis high despite improved treatment.A study conducted in Paraguay demonstrated that tetanus is more frequent in menthan in women, and more common in newborns and children than in adults (VeraMartínez et al., 1976).In Argentina, the annual rates of incidence for the period 1965–1977 were 1.2 to1.7 per 100,000 inhabitants (except in 1967, when the rate was 3.1 per 100,000inhabitants). The disease was more frequent in subtropical or temperate provincesthan in the cold Patagonian provinces. Average hospital admissions for tetanus inBuenos Aires between 1968 and 1973 were higher during the hot months. Tetanusmortality in these municipal hospitals reached 35.8% and was eight times higher inchildren younger than 15 days than in other age groups (Mazzáfero et al., 1981).Table 4 shows the morbidity distribution by climate for tetanus in Argentina duringthe period 1967–1977. In 1990, 49 cases were reported; in 1991, there were 38 casesof all ages; and in 1992, there were 7 neonatal cases. Underreporting is evident,since the number of deaths exceeds the number of patients, as indicated by theauthorities in charge of the National Disease Surveillance System (Argentina,Ministerio de Salud y Acción Social, 1990, 1991, and 1992).Occurrence in Animals: The disease is infrequent in animals. There are enzooticareas, particularly in the tropics. Horses are the most susceptible species. Cases alsooccur in sheep and cattle.The Disease in Man: It is characterized by painful spasms of the masseter muscles(trismus) and neck muscles (rictus), but it frequently affects other muscles inthe body. Although the average incubation period is 14 days, it may vary from lessthan two days to several months. If the disease is not complicated by other infections,temperature may be normal or only slightly elevated. Reflexes are exaggerated,and rigidity of the abdominal muscles, urine retention, and constipation arecommon. The case fatality rate is high, but varies from one country to another. In theUS, fatality fell from 90% in 1947 to 60% in 1969. In 1989–1990, it was 17% inpatients aged 40 to 49 and 50% in those aged 80 or older. The disease is much moresevere when the incubation period is short and convulsions appear early. The longer,more frequent, and more intense the convulsions become, the worse the prognosis.The symptomatology of neonatal tetanus is the same as that of the disease inadults; only the infection’s portal of entry differs. In newborns, the infection usuallyenters through the umbilical stump. At other ages, the route of entry is a wound.Puncture wounds produced by contaminated objects or trauma wounds are especiallydangerous. Surgical interventions and induced abortions performed withoutadequate asepsis have given rise to tetanus.