Abstract
BACKGROUND: Malaria during pregnancy can have severe consequences, such as abortion, intrauterine growth restriction, low birth weight, maternal and fetal anaemia, congenital malaria and fetal death. Submicroscopic congenital malaria is traditionally defined as a Plasmodium infection detected only by molecular methods in the umbilical cord blood and/or in the newborn peripheral blood. Data on the prevalence and risk factors associated with submicroscopic malaria in pregnant women from Latin America are scarce. This study aimed to describe the first submicroscopic infection rate by Plasmodium sp. in umbilical cord blood in an area of low malaria endemicity and the risk factors that are associated with congenital malaria transmission. METHODS: This study used samples and data from a prospective cohort study of pregnant women in Fray Bartolomé de las Casas, Guatemala, between 2009 and 2011. A random sample of umbilical cord samples (negative by microscopy) was tested using quantitative real-time polymerase chain reaction (qPCR) to determine the prevalence of submicroscopic Plasmodium sp. INFECTIONS: A case-control study was then conducted to identify the risk factors in this population associated with submicroscopic congenital malaria. The cases were newborns with an umbilical cord sample confirmed with submicroscopic malaria infection. The controls consisted of newborns and umbilical cord samples, which yielded negative results for malaria infection by both microscopy and qPCR. RESULTS: A total of 442 cord samples from a subsample of 480 randomly selected samples were analysed by qPCR (92%). Among these samples, 54 tested positive for malaria, resulting in a submicroscopic cord blood malaria prevalence of 12.2% (95% CI 9.3% -15.6%). The case-control study included 54 cases and 51 controls. Submicroscopic maternal Plasmodium sp. infection (aOR 7.55, 95% CI 1.84-51.5) and gravidity (aOR 1.49, 95% CI 1.13-2.04) were associated with a higher risk of submicroscopic congenital malaria infection. CONCLUSION: Submicroscopic malaria infection in pregnancy was shown to be associated with risk of submicroscopic congenital malaria infection. Given the deleterious effects observed of any malaria infection in pregnancy, prompt diagnosis and treatment of malaria infection should be emphasized.