Malaria
is highly endemic in Nigeria and poses a major health challenge with attendant
risk of morbidity and mortality contributing to loss of productivity and
economic development.
The most vulnerable groups are children below 5 years of age and pregnant women, particularly women in their first and second pregnancy.
The preferential susceptibility of these sets of pregnant women may be related to some evidence that immune-suppression associated with pregnancy occurs more in the first than subsequent pregnancies. Previously, the depression of cell mediated immune response to Plasmodium falciparum antigens has been implicated in this phenomenon.
Age
has also been implicated as epidemiological studies have shown that malaria in pregnancy
is more prevalent in younger than older age groups. Currently, susceptibility
to Plasmodium parasitaemia has
been linked to the level of antibodies to placental sequestrated parasites. Indeed
these parasites preferentially adhere to chondroitin sulphate-A receptors (CSA)
expressed by the syncytiotrophoblasts in the placenta.
Women
in their first and second pregnancies are more susceptible as anti-adhesion
antibodies against CSA binding parasites develop after successive pregnancies.
The
presence of parasites in peripheral blood without symptoms is common in
hyper-endemic areas, and is associated with chronic anemia and placental
sequestration.
In Nigeria, 11% of maternal deaths are attributed
to malaria. To further buttress the worrisome malaria picture, many researchers
have reported high prevalence rates of malaria in pregnancy in different parts
of Nigeria, ranging from 19.7% to 72.0%.
A prevalence of 29% of malaria parasitaemia was reported in a study conducted in Abakaliki comparable to previous works done in other areas; 57% in Libreville, Gabon,63.5% in Awka, Nigeria in 2003 and 58.4% in Enugu. In most of these findings susceptibility was more in primigravidae. Furthermore, asymptomatic malaria parasitaemia occurred more in the first and second trimesters than third trimester.
A
study conducted in Mbale-Uganda in 2011 by Daniel J. Kyabayinze et al found a malaria prevalence of 38% using microscopy
and 54% with RDTs among febrile pregnant women at ANC. In another study
conducted in Abakaliki by Nwali et al;
Two hundred and fifty women were screened for
asymptomatic malaria parasitaemia and placental parasitisation in 2014, out of
this number, (194/250) 77.6% had peripheral parasitaemia while (227/250) 90.8%
had placental parasitisation.
In
some studies, the relatively lower prevalence rates of malaria infection among
pregnant woman who assess their antenatal care in the sub-region may not be as
a result of the development of higher levels of the acquired ant-malaria
immunity among them, but a more plausible explanation to this lower prevalence
rate could be attributed to increased malaria awareness among women of child-bearing
age in many endemic areas of the sub-Saharan Africa and the intensified efforts
of various health authorities at the local, regional and national levels in the
control and prevention of malaria in pregnancy.
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