CLUSTERING OF GIARDIOSIS AMONG AIDS PATIENTS IN LOS-ANGELES-COUNTY

The purpose of this study was to determine the mode of the spread of t he enteric parasitic infections among HIV+/AIDS patients attending the AIDS clinic of the King/Drew Medical Center in Los Angeles. Two hundr ed forty three patients diagnosed with HIV+/AIDS agreed to participate . The study was conducted by several interviews, questionnaires and st ool sample collections over a one year period. Stool samples were proc essed for protozoan cysts and Helminth Ova using standard stool concen tration and staining techniques. An indirect immunofluorescence monocl onal antibody technique was also used as an alternate to detect the pa rasites in samples. Forty three cases were positive for Giardia Lambli a (17.7%) and 10 cases were positive for Cryptosporidium (4%). No Helm inth Ova were detected. The majority of the participants were African- American (72.6%) and 27.6% were Hispanic. Clustering studies were perf ormed to determine the mechanism of spread of the parasites among the population study. The Nearest Neighbor Clustering Technique (NNT) was used to determine if there was spatial clustering of positive cases. G eocoding with the MapInfo Program was performed to determine the preci se coordinates of the residence of the subjects. Application of the NN T showed a high degree of clustering for Giardia. The NNT statistic fo r Giardia was significant with the p value for 0.020 using the Simes m ultiple comparisons correction. Examination of the map plots indicated that there were two areas with high Giardia prevalence, one in Hollyw ood region, the other in South-Central Los Angeles. The odds ratio for sexual orientation was 14.2 (for homosexuals vs heterosexuals) with a p value of less than 0.001. These findings strongly suggest that male homosexual contact was the main mode of transmission of observed Giar dia cases.