Pathogenesis and immune response to Paracoccidioides brasiliensis in the fructivorous bat, Artibeus lituratus.

Groups of neotropical bats (Artibeus lituratus) were inoculated by the intraperitoneal or intranasal routes with varying doses of yeast phase Paracoccidioides brasiliensis. Bats infected with 10(6) viable yeast cells intraperitoneally developed fatal, disseminated disease, with delayed hypersensitivity appearing within 2 weeks. No precipitating antibodies were detected up to 7 weeks post-exposure. After intranasal instillation of 10(5) viable P. brasiliensis, the disease spread from the lung to the spleen by 3 weeks and to the liver by 9 weeks. As few as 10 viable cells were capable of causing pulmonary disease. Antibodies were detected at 5 weeks and persisted for several weeks thereafter. No viable P. brasiliensis was recovered from the intestines or fecal contents of any bats. Artibeus lituratus appears to be very susceptible to paracoccidioidomycosis by the respiratory route. The resulting immune response is characterized by delay appearance of precipitating antibodies and a moderate degree of delayed hypersensitivity. The pathogenesis of the resulting disease is similar to that observed in humans. The absence of intestinal involvement, even in chronic systemic disease, suggests that bats do not play a direct role in dissemination of this fungus in nature.

Role of bats in the ecology of Paracoccidioides brasiliensis: the survival of Paracoccidioides brasiliensis in the intestinal tract of frugivorous bat, Artibeus lituratus.

The fruit-eating bat, Artibeus lituratus, was fed known quantities of viable yeast cells and mycelial particles of Paracoccidioides brasiliensis in an attempt to assess the role of this animal in the distribution of this agent in nature. Results of mycosal cultures of the stomach, upper intestine, lower intestine and rectum clearly showed that the fungal cells were unable to survive more than 8 hours in the digestive tract of the bat. The mycelial particles were more susceptible than the yeast and were killed before passing to the rectum. The fungus died rapidly in the voided fecal material. These findings indicate the improbability of isolating P. brasiliensis from the digestive tract of wild captured bats and show that A. lituratus probably plays no role in the distribution of this fungus in nature.

Etiology of respiratory tract infections in children in Cali, Colombia.

One hundred eighty children hospitalized for acute respiratory disease were studied in Cali, Colombia. In the majority of patients, pneumonia was the reason for hospitalization and remained the final diagnosis. Fifty-one cases of pneumonia of indeterminate etiology comprised the largest single diagnostic category, followed by 38 cases of pneumonia associated with measles, and 22 cases assocaited with serologic evidence of infection with other viral agents or Mycoplasma pneumoniae. Etiologic diagnosis could be assigned with a reasonable degree of confidence in 116 of the 180 patients (64%). The laboratory procedure found most likely to provide the etiologic diagnosis in this series was paired sera specimens for demonstration of rise in antibody titer against the common viral respiratory pathogens. Those most frequently implicated serologically as etiologic agents in the cases studied were, in order of decreasing frequency, measles, influenza, parainfluenza, and adenoviruses.