Respiratory cryptosporidiosis in HIV-seronegative children in Uganda: potential for respiratory transmission

Abstract

Background: Respiratory cryptosporidiosis is recognized as a late-stage complication in persons with human immunodeficiency virus (HIV) infection and AIDS. However, respiratory signs and symptoms are common in otherwise healthy children with intestinal cryptosporidiosis, which suggests that respiratory infection may occur in immunocompetent hosts.

Methods: We recruited children 9-36 months of age who presented with diarrhea to Mulago Hospital in Kampala, Uganda, from November 2007 through January 2009. Children with stool samples positive or negative for Cryptosporidium species were selected for further evaluation, including sputum induction in those with cough or unexplained respiratory signs and collection of saliva and blood specimens. Sputum samples were subjected to comprehensive bacteriologic testing, and both sputum and saliva specimens were tested for Cryptosporidium species by nested polymerase chain reaction.

Results: Of 926 fecal samples screened, 116 (12.5%) were positive for Cryptosporidium. Seventeen (35.4%) of 48 sputum samples tested from children with positive stool samples were positive for Cryptosporidium. Sixteen (94.1%) of the 17 children with confirmed respiratory cryptosporidiosis were HIV seronegative, and 10 (58.8%) of 17 children were not malnourished. None of the 12 sputum specimens from children with negative stool samples tested positive for Cryptosporidium (P = .013, compared with children who tested positive for Cryptosporidium in the stool). Parasite DNA was detected in only 2 (1.9%) of 103 saliva samples (P < .001, compared with sputum samples).

Conclusions: Respiratory cryptosporidiosis was documented in one-third of HIV-seronegative children who were tested. These novel findings suggest the potential for respiratory transmission of cryptosporidiosis. Trial registration. ClinicalTrials.gov identifier: NCT00507871.

Figure 1. Genotyping of Cryptosporidium parasites in sputum and saliva samples

Restriction fragment length polymorphism (RFLP) analysis reveals the genotyping patterns of parasites in the sputum (lanes 1–17) and saliva (lanes 18,19). For sputum isolates, lane numbers correspond with the identification numbers in Table 2. Digestion of secondary PCR products with enzyme AseI (VspI) yields prominent bands at 70, 104 and 561bp for C. hominis, at 104 and 625 to 628bp for C. parvum and at 104, 171 and 456 for C. meleagridis [13]. Positive controls for the most common species in humans are indicated as follows: C. hominis (lane 20), C. parvum (lane 21), C. meleagridis (lane 22). M, 100bp marker.