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

COCCIDIOIDOMYCOSIS 321Colombia, Guatemala, Honduras, Paraguay, Venezuela, and probably Bolivia. Theendemic area in Latin America is estimated to cover 1.5 million km 2 , more than1 million km 2 of which are in Mexico (Borelli, 1970).Occurrence in Man: In some endemic areas the rate of infection seems to bevery high and it is estimated that in some of these areas in the United States nearly100% of the population could contract the infection within a few years (Fiese, citedby Ajello, 1970). There are an estimated 25,000 to 100,000 cases in the US eachyear. Approximately 20% of the cases involve people who live outside endemicareas and become infected while visiting them (Drutz and Huppert, 1983). Somecases have also been described in Europe (the former Czechoslovakia, Great Britain,and Denmark). The rate of reactors to the skin test in different endemic areas variesfrom 5% to more than 50% of the population. There is a significant increase in casesin the United States. In 1991, 1,208 new cases were recorded in California as comparedto 450 cases per year on average in the previous five years. Of these cases,80% came from Kern County, a known endemic area. Sixty-three percent of thecases were reported from October through December. The outbreak in Californiacould have been associated with prolonged drought, followed by occasional heavyrains. Another important factor could be migration to California of people not previouslyexposed to the fungus. In the United States, endemic areas are found inArizona, California, Nevada, New Mexico, Texas, and Utah (CDC, 1993). The dataon South America are more fragmentary, but the rate of infection appears to be lowerin this region.Occurrence in Animals: Natural infection has been found in many species ofmammals. Infection is very frequent in cattle and dogs in endemic areas. Veterinaryinspection has discovered coccidioidomycosis lesions in 5% to 15% of the cattleslaughtered in abattoirs in central Arizona (USA). Several million cattle are thoughtto be infected in the endemic areas of the southwestern United States. Infection hasalso been demonstrated in sheep, horses, swine, and wild rodents.Several studies were carried out on animals in the endemic region of Mexico. Inthe state of Sinaloa, sera from 100 hogs and 200 cattle were examined by immunoelectrophoresisand reactions were found in 12% and 13%, respectively (VelascoCastrejón and Campos Nieto, 1979). In the state of Sonora, when the intradermaltest using coccidioidin was conducted on 459 cattle, 6.75% tested positive. Anotherstudy performed histological examinations of granulomatous lesions discovered in3,032 slaughtered cattle and found that the lesions in 77 (44%) of 175 animals confiscatedfor suspected tuberculosis were actually caused by C. immitis, indicating arate of infection of 2.5% in all the animals (Cervantes et al., 1978).The Disease in Man: The incubation period lasts from one to four weeks. Anestimated 60% of infections occur asymptomatically and are only recognizable withthe intradermal test. The remaining 40% present as a respiratory disease with acutesymptoms similar to those of influenza and that generally pass without sequelae.About 5% of primary infections develop either an erythema multiforme or an erythemanodosum arthralgia. What is more common, however, is a light erythrodermaor maculopapular eruption. Chest pain can be strong and pleuritic. The radiologicalpicture is varied, but hilar adenopathy with alveolar infiltrates and infiltrates thatchange area are indicative of coccidioidal pneumonia (Ampel et al., 1989). When