Thrombocytopenia in plasmodium parasitized pregnant women in the Niger Delta of Nigeria

O Erhabor¹, Z A Jeremiah¹, T C Adias², M L Hart¹

¹Department of Medical Laboratory Sciences, College of Health Sciences, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria; ²Department of Medical Laboratory Sciences, Rivers State University of Science and Technology, Port Harcourt, Nigeria

Background: Malaria infection during pregnancy is a major public health problem in tropical and subtropical regions of the world. Hematological changes associated with malaria in pregnancy are not well documented, and have focused predominantly on anemia. The aim of this study was to determine the impact of Plasmodium parasitaemia on the platelet count of pregnant women in the Niger Delta of Nigeria.

Methods: In this observational study we reviewed the platelet counts from routine complete blood count (CBC) in a cohort of healthy (pregnant and nonpregnant) and malaria-infected pregnant women attending antenatal clinics. A platelet count of 100 × 10⁹/L was the threshold at two standard deviations below the mean for healthy Nigerian pregnant women used to indicate thrombocytopenia. Differences in platelet counts were compared based on malaria species and parasitemia in matched nonpregnant and pregnant women. Blood smears from Quantitative Buffy Coat malaria-positive samples stained with Giemsa were used for determination of parasite load and specie identification by light microscopy.

Study design: This case control study evaluated the effect of malaria parasitemia on the platelet count of 50 plasmodium parasitized pregnant subjects. Fifty nonmalaria parasitized pregnant women and fifty nonpregnant and nonmalaria-infected subjects served as control.

Results: The mean platelet counts (×10⁹/L) were significantly lower in pregnant subjects with an episode of Plasmodium falciparum malaria 111.3 ± 9.3 × 10⁹/L compared to nonparasitized and healthy nonpregnant controls (255.09 ± 24.10 and 270 ± 51.5 × 10⁹/L) respectively. Platelet count values were 112.5 ± 9.68 × 10⁹/L and 126.3 ± 16.7 × 10⁹/L for the primigravidae and multigravidae respectively. (χ2 = 10.46; P = 0.05). Parasite density was significantly higher among Plasmodium parasitized primigravidae compared to multigravidae 2150 (1638–2662) parasites/µL in primigravidae women compared to 1826 (1430–2222) parasites/µL in multigravid women. The mean parasite count in Plasmodium falciparum parasitized subjects was 2650 ± 234 parasites/µL, 95% confidence interval (2092–3118). Malaria parasite was found to exert a significant reduction in platelet density in parasitized subjects. This reduction was more pronounced in primigravidae and multigravidae. An inverse relationship was established between parasite density and platelet count (y = -0.020 × +86.2, r = -0.3).

Conclusion: There is need for a strengthened antenatal care system with increased awareness of the problem among communities most affected by malaria. Preventative strategies including regular chemoprophylaxis, intermittent preventative treatment with antimalarials and provision of insecticide-treated bed nets should be implemented as well as integration of malaria control tools with other health programmes targeted to pregnant women and newborns.

Keywords: thrombocytopenia, malaria, pregnancy, Niger Delta, Nigeria