Cross-Resistance between Sulfadoxine-Pyrimethamine and Other Antimalarial Drugs: A Study of Pregnant Women in Ilorin Kwara State Nigeria
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Date
2025-03-10
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Abstract
Antimalarial resistance remains a serious problem in malaria-endemic regions, particularly in
pregnant women, who are likely to suffer from complications. The research evaluates the
resistance to commonly employed antimalarial medications—Chloroquine, Artesunate, and
Arthether—among pregnant women in Ilorin, Nigeria, at different trimesters and during delivery.
Cross-sectional study was conducted among 253 pregnant women presenting at antenatal clinics
within Ilorin, Kwara State. Venous blood from study participants in different pregnancy stages
(first trimester, second trimester, third trimester, and upon delivery) were drawn. Schizont
maturation inhibition method was used in the drug susceptibility test to establish resistance to
Chloroquine, Artesunate, and Arthether. Chloroquine resistance prevalence was moderately low
at varying levels of between 7.9% upon delivery and 12.2% in the second trimester. Resistance
against Artesunate, however, rose progressively as pregnancy advanced up to 60.0% in the third
trimester, suggesting loss of drug effectiveness toward the end of pregnancy. Arthether resistance
was variable, with the highest prevalence in the first (43.0%) and second (33.8%) trimesters,
dropping to 0% during the third trimester, then rising again to 38.1% at delivery. Crossresistance evaluation showed a high positive correlation between SP resistance and Artesunate
resistance during the first (OR = 2.53, p = 0.007) and second trimesters (OR = 2.19, p = 0.043),
which suggests shared resistance mechanisms. In contrast, SP resistance was reversely associated
with Chloroquine resistance at the second trimester (OR = 0.43, p = 0.021) and at delivery (OR =
0.27, p = 0.042), demonstrating that individuals resistant to SP were less resistant to
Chloroquine. The findings prove evidence of enhanced resistance to Artesunate, particularly as
gestation age increases, making its usage among pregnant women challenging. Cross-resistance
between SP and Artesunate increases the need for continued caution and possible alteration of
treatment of malaria in pregnant women. Other treatment regimens to manage malaria in
pregnancy effectively should be the focus of future research.