Predictive markers of transmission in areas with different malaria endemicity in north-eastern Tanzania based on seroprevalence of antibodies against Plasmodium falciparum.

OBJECTIVE: A community-based cross-sectional study was done to assess Plasmodium falciparum exposure in areas with different malaria endemicity in north-eastern Tanzania using serological markers; PfAMA-1 and PfMSP-119. RESULTS: Bondo had a higher seroprevalence 36.6% (188) for PfAMA-1 as compared to Hai 13.8% (33), χ2 = 34.66, p < 0.01. Likewise, Bondo had a higher seroprevalence 201(36.6%) for PfMSP-1 as compared to Hai 41 (17.2%), χ2 = 29.62, p < 0.01. Anti-PfAMA-1 titters were higher in malaria positive individuals (n = 47) than in malaria negative individuals (n = 741) (p = 0.07). Anti-PfMSP-1 antibody concentrations were significantly higher in malaria-positive individuals (n = 47) than in malaria-negative individuals (n = 741) (p = 0.003). Antibody response against PfAMA-1 was significantly different between the three age groups; < 5 years, 5 to 15 years and > 15 years in both sites of Bondo and Hai. Likewise, antibody response against PfMSP-119 was significantly different between the three age groups in the two sites (p < 0.001). We also found significant differences in the anti-PfAMA-1and anti-PfMSP-119 antibody concentrations among the three age groups in the two sites (p = 0.004 and 0.005) respectively. Immunological indicators of P. falciparum exposure have proven to be useful in explaining long-term changes in the transmission dynamics, especially in low transmission settings.

Cryptococcal antigen prevalence in HIV-infected Tanzanians: a cross-sectional study and evaluation of a point-of-care lateral flow assay.

OBJECTIVES: Cryptococcal antigen (CRAG) screening at antiretroviral therapy (ART) initiation and pre-emptive antifungal treatment for those testing positive could prevent many cases of cryptococcal meningitis (CM). To investigate whether CRAG screening would be feasible in Tanzania, we conducted a cross-sectional study measuring CRAG prevalence in ART clinic patients and comparing the novel lateral flow assay (LFA) with the cryptococcal latex agglutination (LA) test. METHODS: Consecutive HIV-infected outpatients with CD4 counts <200 cells/µL, who were ART naive or had been on ART for <6 months, were screened for CRAG using the LA and LFA kits. For further assay validation, HIV-infected inpatients with suspected cryptococcal disease were also tested using the LA and LFA kits. RESULTS: Cryptococcal antigen was detected in seven of 218 ART clinic attendees (3%). Six patients (5%) with CD4 cell counts ≤100 cells/µL (n = 124) were CRAG-positive. Agreement between the LA and LFA test in the 218 outpatients was 100%. Another 101 inpatients were tested for CRAG, of whom 56 (55%) were CRAG-positive on both the LA and LFA tests. One patient was positive using the LFA test but negative on the LA test. The overall agreement between the two assays was 99.7%, kappa coefficient 0.99 (standard error 0.06, P < 0.001). CONCLUSIONS: Five percentage of ART clinic patients with CD4 cell counts ≤100 cells/µL in northern Tanzania had asymptomatic cryptococcal antigenaemia, suggesting that CRAG screening would be worthwhile in the Tanzanian ART programme. The LFA is a reliable, cheap and practical alternative to LA for detection of CRAG.