Occurrence of leptospirosis among suspected cases in Chennai, Tamil Nadu.

Objective: To evaluate the serological profile of leptospirosis by microscopic agglutination test (MAT) and dark field microscopy (DFM) and to determine the serovar prevalence rate among patients with pyrexia of unknown origin. Materials and Methods: A total of 3830 blood samples were received from different hospitals and laboratories in and around Chennai. They were screened for leptospirosis by MAT and direct observation of live Leptospira by DFM. Results: A total of 748 (19.5%) Leptospira positive cases were identified; among these, 36.76% were Leptospira australis, 30% were Leptospira canicola, 14.57% were Leptospira autumnalis, 12% were Leptospira icterohaemorrhagiae, 4.68% were Leptospira patoc and 1.87% were Leptospira grippotyposa. Patients were in the age group of 1-86 years, with a median age of 43.5 years. 50% positive cases were in the age group of 10-35 years. Majority of the Leptospira infected cases were males (62.98%) than females (37.02%). Conclusion: Leptospirosis occurs in Chennai throughout the year although the number and positivity of cases increased during the monsoon season.

The use of dried blood spots on filter paper for the diagnosis of HIV-1 in infants born to HIV seropositive women.

Polymerase chain reaction (PCR) is the most sensitive test to diagnose HIV-1 infection among infants born to HIV seropositive mothers. The purpose of this study was to evaluate the use of dried blood spot (DBS) specimens for PCR and to compare it with whole-blood stored in tubes for HIV-1 DNA PCR. Five hundred and seventy-seven whole-blood infant samples were tested using HIV-1 qualitative in-house nested DNA PCR. Three hundred and fifty-nine samples were from infants at 48 hours of birth and 218 samples at second month. All positive samples tested from whole-blood and every fifth negative sample were coated onto filter paper. DNA was extracted from the filter paper and was amplified using in-house nested PCR. Among the whole-blood samples tested using HIV-1 DNA PCR, 19 of 359 (5.29%) samples were HIV-1 positive and 340 (94.7%) were negative at 48 hours of birth. At second month, 19 (8.7%) of the 218 samples were positive and 199 (91.2%) were negative. Using dried filter paper, 18 samples (95%) tested positive from 19 positive samples (using whole-blood) and 1 tested negative at 48 hours of birth. The 68 negative samples tested using whole-blood were also negative in the DBS test (sensitivity 95% and specificity 100%). At second month, 19 were positive and 40 samples (every fifth sample of 199) were negative (sensitivity and specificity, 100%). PCR performed using DNA extracted from filter paper permits the diagnosis of HIV-1 infection among infants born to HIV-1 seropositive mothers. This assay is simple, rapid, sensitive and specific and can be used in resource limited settings.