Performance of rapid immune-chromatographic test and the effect of age and parity on malaria infection among expectant women in Kericho County
Njeru, Annastasia Wangari
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Malaria is a major contributor of ill health and death particularly among infants and pregnant women in sub-Saharan Africa. The infected erythrocytes sequester in the placenta and may be present throughout the whole pregnancy period. Although microscopy is the gold standard method currently acceptable in diagnosis of malaria in hospital, it is unreliable because during pregnancy, malaria parasites disappear from peripheral circulation and remain undetectable through microscopic examination. This technique also requires expertise to perform and it is time consuming hence difficult to implement in remote areas where malaria is more common. The ability of rapid immunochromatographic tests to detect malaria parasites sequestered in the placenta has been reported but their accuracy and sensitivity in detection of malaria among pregnant women under different ecological settings remains unclear. This study compared the performance of the rapid immunochromatographic strip test relative to microscopy using polymerase chain reaction as a confirmatory test in malaria diagnosis among pregnant women in Kericho Highlands. The effect of age and parity on malaria prevalence and parasitaemia level was also examined. Blood samples from a total of 314 pregnant women attending the antenatal clinic were screened for malaria parasites using microscopy, rapid ICT and PCR. Structured questionnaires were also administered to obtain information on the effect of age and parity on malaria prevalence and parasitaemia level. Data were analyzed using Chi-square, logistic regression analysis, odds ratio tests and Cohen kappa index computation. Out of the 314 samples analyzed by microscopy, 44 samples (14.0%) were positive for P. falciparum while rapid ICT diagnosed 62 (19.7%) as positive for P. falciparum. The sensitivity and specificity of rapid ICT was 84.4% and 96.8% respectively while that of microscopy was 68.8% and 100.0% respectively. The Cohen kappa index (k) indicated a moderate level of agreement between results of rapid ICT and microscopy and high level of agreement when rapid ICT results were compared against microscopy and PCR results (κ = 0.517; p <0.001 and κ = 0.821; p <0.001) respectively. Chi-square analysis tests showed that parity had no significant effect on malaria prevalence (P < 0.001). Odds Ratio tests showed no significant difference in parasitaemia in infected multiparous and primiparous women (p=0.748) and that age had no significant effect on parasitaemia levels among the study population (p=478). Binary logistic regression analysis revealed that maternal age and parity are not significant predictors of malaria prevalence and parasitaemia level (P > 0.05). The findings of this study suggest the potential adoption of rapid ICT as a complementary epidemiology tool for malaria diagnosis among expectant women in areas of low parasitaemia and where microscopy is difficult to implement due to limited resources. The interventions on malaria control should also be geared towards control of malaria among all pregnant women irrespective of age and parity.
- MST-Zoological Sciences