A case-control study to determine whether active plasmodium falciparum infection is a possible risk factor for pre-eclampsia/ eclampisa.

Abstract

INTRODUCTION: Despite progress made towards understanding the pathophysiology of preeclampsia the precise aetiology of PET remains an enigma making primary prevention impossible and disease progression unpredictable. PET is associated with 50,000 maternal deaths annually and in Uganda is ranked amongst the top five causes of maternal mortality. Most of the clinical malaria attacks in Uganda are due to the P.falciparum parasite. Both pre-eclampsia/eclampsia and malaria have been known to be more common during the rainy season and have strikingly similar pathophysiology. Both diseases take effect at the placental level causing poor pregnancy outcomes due to altered placental integrity. Some forms of malaria mimic PET i.e., cerebral and algid malaria mimic eclampsia and HELLP syndrome respectively. Morbidity and mortality from malaria may therefore be erroneously attributed to PET. This study sought to investigate a possible association between malaria and pre-eclampsia/eclampsia in the bid to use malaria control in pregnancy for secondary prevention of HT diseases of pregnancy. STUDY OBJECTIVE The objective of the study was to determine whether active P.falciparum malarial infection is a possible risk factor for pre-eclampsia/eclampsia. STUDY DESIGN: The study was conducted as an unmatched case-control with 70 cases and 141 controls. STUDY SITE: The study was conducted in Lower Mulago Hospital labour suite. STUDY POPULATION: These were mothers presenting for delivery in Lower Mulago Hospital with a gestation age or clinical examination of more than thirty weeks. METHODS: Consecutive sampling was carried out and mothers recruited as cases on the basis of a single raised BP that persisted over the next four hours (systolic>_l40mmHg diastolic 2 90mmHg) and significant urine protein of (+) or more on dipstick method. Controls were normotensive mothers consenting to the study with negative or insignificant urine protein. They were selected randomly with two controls recruited daily throughout the study period. Demographic data, information on antenatal practices, malaria prevention/treatment and known risk factors for PET were collected. At delivery 2-41111s of maternal venous blood were drawn aseptically from the antecubital vein and prepared as blood smears for microscopy to detect malaria. A rapid malarial antigen test was also carried out on the same sample. Placentae were subjected to histological examination for malaria and graded as active, active-chronic, past or no infection. Data were entered and analysed using EPI-INFO with study power taken as 80% and a p-value of 0.05 as significant. RESULTS: The two study groups were comparable in their demographic characteristics and most of their antenatal practices regarding malaria prevention and treatment. Sulphadoxinepyrimethamine (SP) was the most commonly received antimalarial antenatally but many discrepancies abound concerning its documentation as IPT. Of statistical significance was the fact that cases had more documentation of IPT (p-val 0.042). This proved to be the logical explanation for the lower proportion of placental malaria found amongst the cases (17.1% vs. 25.5%). Placental histology was the most sensitive method for diagnosing malaria at delivery while microscopy compared favorably with rapid malarial antigen testing. Active and active-chronic malaria infection formed the bulk of placental infection in both study groups (12.8% cases, 22.7% controls). Placental malaria infection was more common at the start and peak of the rainy seasons. Amongst the cases placental malaria was more prevalent with mild PET (75%) than severe PET (25%) and not at all associated with eclampsia. CONCLUSIONS: The results of this study showed no association between active malaria infection and PET. The low rates of placental parasitaemia can be attributed to increased use of IPT but there is still need to improve on documentation of IPT. The practice of malaria control through IPT should be intensified. The effect of HN, malaria and PET could not be clearly established in this study and provides an area for further research. This study should be carried out in different geographical locations of the country especially where the malaria parasitemia rates are high. A study population naive to IPT might also yield different results.