Malaria in pregnancy in rural Gabon: a cross-sectional survey on the impact of seasonality in high-risk groups.
BACKGROUND
Malaria remains one of the most important infectious diseases in pregnancy in sub-Saharan Africa. Whereas seasonal malaria chemoprevention is advocated as public health intervention for children in certain areas of highly seasonal malaria transmission, the impact of seasonality on malaria in pregnancy has not yet been investigated for stable, hyper-endemic transmission settings of Equatorial Africa. The aim of this study was to investigate the influence of seasonality on the prevalence of malaria in pregnancy in Gabon.


METHODS
The study was conducted at a rural district hospital in Gabon between January 2008 and December 2011. At first antenatal care visits demographic data, parity, age, and gestational age of pregnant women were documented and thick blood smears were performed for the diagnosis of malaria. Seasonality and established risk factors were evaluated in univariate and multivariate analysis for their association with Plasmodium falciparum infection.


RESULTS
1,661 pregnant women were enrolled in this study. Participants presenting during high transmission seasons were at significantly higher risk for P. falciparum infection compared to low transmission seasons (adjusted odds ratio [AOR] 1.91, 95% confidence interval [CI] 1.39-2.63, p < 0.001). Established risk factors including parity (AOR 0.45, CI 0.30-0.69, p < 0.001 for multipara versus paucipara) and age (AOR, CI and p-value for women aged 13-17, 18-22, 23-27 and ≥ 28 years, respectively: AOR 0.59, CI 0.40-0.88; AOR 0.57, CI 0.34-0.97; AOR 0.51, CI 0.29-0.91) were significant risk factors for P. falciparum infection. High-risk groups including nulli- and primipara and younger women aged 13-17 years showed a disproportionately increased risk for malaria in high transmission seasons from 17% to 64% prevalence in low and high transmission periods, respectively.


CONCLUSIONS
Seasonal variations lead to important differences in the risk for P. falciparum infection in pregnancy in the setting of central African regions with stable and hyper-endemic malaria transmission. The seasonal increase in malaria in pregnancy is most pronounced in high-risk groups constituted by young and pauciparous women. The evaluation of tailored seasonal prevention strategies for these high-risk populations may, therefore, be warranted.
Mario J
MJ
Jäckle
Christian G
CG
Blumentrath
Rella M
RM
Zoleko
Daisy
D
Akerey-Diop
Jean-Rodolphe
JR
Mackanga
Ayôla A
AA
Adegnika
Bertrand
B
Lell
Pierre-Blaise
PB
Matsiegui
Peter G
PG
Kremsner
Ghyslain
G
Mombo-Ngoma
Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon. michael.ramharter@medizin.uni-tuebingen.de.
Michael
M
Ramharter
D000293:Adolescent; D000328:Adult; D000818:Animals; D003430:Cross-Sectional Studies; D005260:Female; D005681:Gabon / Q000453:epidemiology; D006801:Humans; D008288:Malaria / Q000453:epidemiology*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population; D012621:Seasons; D055815:Young Adult