Expectoration of Cryptosporidium Parasites in Sputum of Human Immunodeficiency Virus–Positive and –Negative Adults

Abstract

Respiratory cryptosporidiosis is thought to be a rare, end-stage complication of HIV. Few studies have systematically examined the frequency of such infection in adults. Sputum specimens submitted for tuberculosis (TB) testing at Mulago Hospital, Uganda, were anonymously retested for <i>Cryptosporidium</i> using real-time polymerase chain reaction (PCR). Visual confirmation using immunofluorescence confocal microscopy was performed for a subset of PCR-positive samples. Of 824 sputum samples tested, 24 (2.9%) were <i>Cryptosporidium</i> positive. Prevalence in sputum ranged between 0% and 10% in each month of the study and exceeded TB prevalence in some months. In this referral population, respiratory <i>Cryptosporidium</i> prevalence was lower in people with HIV (1.3% versus 4.4% without HIV, <i>P</i> = 0.028) and higher in those with TB (6.8% versus 2.6% without TB, <i>P</i> = 0.086). The weak association between respiratory <i>Cryptosporidium</i> infection and TB persisted after controlling for HIV (odds ratio = 3.2, 95% confidence interval: 0.9, 11.8; <i>P</i> = 0.080). This is the first study to document adult respiratory tract cryptosporidiosis in a referral population with presumed TB. These findings 1) confirm that <i>Cryptosporidium</i> respiratory infection occurs in HIV-negative and -positive adults; 2) suggest there is potential for <i>Cryptosporidium</i> to be disseminated or transmitted by coughing or expectoration; and 3) identify possible synergy between <i>Cryptosporidium</i> and TB in the respiratory tract.