Evidence of previous infection with Mycobacterium avium-Mycobacterium intracellulare complex among healthy subjects: an international study of dominant mycobacterial skin test reactions.

Skin tests with 0.1 mL of intermediate-strength Mycobacterium tuberculosis purified protein derivative (PPD) and 0.1 mL of Mycobacterium avium sensitin were conducted on 484 healthy subjects from diverse geographic sites. Reactions of > or = 5 mm to one antigen that exceeded the reaction to the other by > or = 3 mm were considered M. avium- or PPD-dominant. PPD-dominant reactions were more frequent at sites where routine Bacille Calmette-Guérin immunization is done or where there are high rates of tuberculosis: New Hampshire, 2%; Boston, 7%; Finland, 14%; Trinidad, 26%; and Kenya, 28%. However, rates of M. avium-dominant reactions ranged from 7% to 12% at all sites. Analysis of dominant reactions based on a more stringent 10-mm minimum reaction size showed similar trends. These data suggest that exposure to MAC is similar in developed and developing countries but that broad mycobacterial immunity is greater in developing countries and may contribute to the lower rates of disseminated MAC infections in AIDS in these areas.

Epidemiologic and clinical features of an outbreak of bubonic plague in New Mexico.

An outbreak of seven cases of bubonic plague in New Mexico was investigated. Clinical features were studied and correlated with field studies in an attmept to determine the source of infection in patients with indefinite histories of exposure. Most patients presented with fever, malaise, and an acute painful lymphadenitis (bubo). One death occurred in a patient with bubonic-septicemic plague complicated by meningitis due to Yersinia pestis. All patients lived in rural or semirural areas, and most had been in the general vicinity of their usual residence during the six days prior to onset of symptoms. The outbreak was associated with probable epizootics in rodents in two different areas of the state. One case was traced to direct hand contact with plague-infected rabbits. One patient developed insect bites after sleeping in the same bed with a flea-infested cat. Three of the other five patients had insect bites, presumably flea bites, but none of the five recalled contact with rodents or rabbits. Four of the five, however, had been in contact with dogs or cats that were later shown to have titers of antibody to Y. pestis. These findings provide further support for the hypothesis that contact with domestic dogs and cats may result in direct or indirect transmission of Y. pestis to humans.

Epidemiologic investigation of echinococcosis in American Indians living in Arizona and New Mexico.

Ten cases of echinococcosis diagnosed in American Indians in Arizona and New Mexico between 1972 and 1975 were investigated as part of a regional epidemiologic study. Patients were visited at home to discover factors associated with local parasite transmission, to detect possible additional cases among family members, and to perform diagnostic tests on dogs. Six patients were Navajo, 2 Zuni, and 2 Santo Domingo Indians. An additional case in a Navajo man was detected by serologic testing of patients' family members; this was the 20th case diagnosed in the region since 1965. Dogs owned by three of the Navajo patients were infected with Echinococcus granulosus. Arecoline-purge testing of 110 dogs in the Zuni pueblo demonstrated echinococcosis in a single stray dog. The findings at slaughter of Navajo-owned sheep indicate that the infection is enzootic in this intermediate host. The epidemiologic findings suggest that humans were infected from dogs which contracted their infections from two sources. The first was sheep raised locally in rural areas of the Navajo Reservation where the infection is enzootic in the dog-sheep cycle; transmission was apparently facilitated by the widespread practice of home butchering. A second source of human infection was dogs which became infected by eating viscera of sheep of off-reservation origin; these sheep were purchased and butchered by individual families in urban areas of the Navajo Reservation and in the Zuni and Santo Domingo pueblos.

Echinococcosis in Arizona and New Mexico. Survey of hospital records, 1969-1974.

In 1974, seven cases of human echinococcosis were diagnosed in Arizona and New Mexico. A retrospective survey of Arizona and New Mexico hospitals obtained data on ten additional cases reported for the 5-year period 1969 through 1973. Sixteen cases were diagnosed as Echinococcus granulosus infections and one as E. multilocularis infection. The latter infection was in an Eskimo from Alaska, where E. multilocularis is endemic. All of the 16 E. granulosus cases were probably acquired autochthonously; 14 were diagnosed in American Indians of the Navajo (8 cases), Zuni (4 cases), and Santo Domingo (2 cases) tribes; the remaining 2 cases were diagnosed in non-Indian women. This is the first published account of echinococcosis autochthonous to Arizona and New Mexico. Evidence suggests that the infection may have been introduced only relatively recently to the areas populated by the American Indians and that parasite transmission to humans is increasing.