Parasite-based diagnosis of malaria in pregnant women in a Tertiary Hospital in southwest Nigeria

Abstract

Background: Malaria in pregnancy has significant adverse consequences for the mother, foetus and  baby. Presumptive diagnosis continues despite recommendation for parasite-based diagnosis. We  performed Paracheck-Pf™, an HRP-II based malaria Rapid diagnostic test (Paracheck-Pf RDT) and  microscopy among pregnant women in a prospective, cross sectional study, at the University College  Hospital in Ibadan, Nigeria.

Methods: The study was conducted between 2009-2011. Consecutive pregnant women presumptively  diagnosed as having malaria >18 years were enrolled after obtaining written informed consent.  Demographic information, symptoms and clinical measurements were obtained. Capillary blood was obtained by finger prick for thick blood smear and RDT evaluation. Summary statistics included mean  (standard deviation) for quantitative variables and percentages for categorical variables. Chi-square,  analysis of variance (ANOVA), the odds ratio (OR) and 95% confidence intervals (CI) were computed with  p-value less than 0.05 considered statistically significant.

Results: Of the 746 pregnant women aged 30.9 ± 4.6 years enrolled, 243 (32.7%) were primigravida. The  mean gestational age was 23.3 ± 9.2 weeks with about 81% in the second and third trimester. The  prevalence of malaria parasitaemia by microscopy and Paracheck-Pf ™ were 22.8% and 24.5%  respectively. The geometric mean parasite density was 2,091/µL (range 40-156,975/µL). HIV positivity rate  was 8.1 % and 16.1% of patients were anaemic (PCV <30%). Women with axillary temperature  >37.40C were significantly more likely to have malaria parasitaemia [p<0.0001] by microscopy. Sensitivity  and specificity of Paracheck overall were 69.9% and 88.2% respectively while those at of parasite densities  >200/µL were 84.8% and 88.7% respectively. Positive and negative predictive values were 66.9%  and over 90% respectively.

Conclusion: RDTs are a reasonable alternative in view of the need for    parasite-based diagnosis of malaria.