Infant sex modifies associations between placental malaria and risk of malaria in infancy

Fetal sex and risk of pregnancy-associated malaria in Plasmodium falciparum-endemic regions: a meta-analysis

In areas of moderate to intense Plasmodium falciparum transmission, malaria in pregnancy remains a significant cause of low birth weight, stillbirth, and severe anaemia. Previously, fetal sex has been identified to modify the risks of maternal asthma, pre-eclampsia, and gestational diabetes. One study demonstrated increased risk of placental malaria in women carrying a female fetus. We investigated the association between fetal sex and malaria in pregnancy in 11 pregnancy studies conducted in sub-Saharan African countries and Papua New Guinea through meta-analysis using log binomial regression fitted to a random-effects model. Malaria infection during pregnancy and delivery was assessed using light microscopy, polymerase chain reaction, and histology. Five studies were observational studies and six were randomised controlled trials. Studies varied in terms of gravidity, gestational age at antenatal enrolment and bed net use. Presence of a female fetus was associated with malaria infection at enrolment by light microscopy (risk ratio 1.14 [95% confidence interval 1.04, 1.24]; P = 0.003; n = 11,729). Fetal sex did not associate with malaria infection when other time points or diagnostic methods were used. There is limited evidence that fetal sex influences the risk of malaria infection in pregnancy.

The association between female newborn and placental malaria infection: A case-control study

INTRODUCTION

There are few published data on the influence of the sex of the fetus or the newborn on the rate of malaria infection. Moreover, the results of these studies are not conclusive. This study was conducted to investigate the association between sex of the newborn and placental malaria infection.

METHODS

A case-control study was conducted at Al Jabalian maternity hospital in central Sudan during the rainy and post rainy seasons from May to December 2020. The cases were women who had placental malaria, while the controls were subsequent women who had no placental malaria. A questionnaire was filled out by each woman in the case and control groups in order to gather demographic data as well as medical and obstetric history. Malaria was diagnosed using blood films. Logistic regression analyses were performed.

RESULTS

There were 678 women in each arm of the study. Compared with the women without placental malaria (controls), women with placental malaria had a significantly lower age and parity. A significantly higher number of the cases had delivered female newborns, 453 (66.8%) vs. 208 (30.7%), P < 0.001. In logistic regression, women with placental malaria: lived in rural areas, had low antenatal attendance, did not use bed nets, and had more female newborns (adjusted odds ratio, AOR = 2.90, 95% CI = 2.08-4.04).

DISCUSSION

Women who delivered female were more likely to have placental malaria. Further research into the immunologic and biochemical parameters is warranted.

Sex-Linked Differences in Malaria Risk Across the Lifespan

Despite the high burden of malaria worldwide, there is surprisingly scarce research on sex-based differences in malaria outside of pregnancy. A more thorough understanding of sexual dimorphism in malaria, and what underlies these sex-based differences, could elucidate the underlying mechanisms driving malaria pathogenesis and has the potential to inform malaria control efforts, including new vaccines. This review summarizes our current understanding of sex-based differences in the epidemiology of malaria across the lifespan, potential sex- or gender-based mechanisms driving these differences, and the knowledge gaps that need to be addressed.

Pregnancy and malaria: the perfect storm

PURPOSE OF REVIEW

Malaria in pregnancy continues to exert a toll on pregnant women and their offspring.

RECENT FINDINGS

The burden of Plasmodium falciparum infection is especially large in Africa, and new data show lasting effects of maternal infection on the infant's neurocognitive development. Elsewhere, P. vivax infection causes relapsing infections that are challenging to prevent. Infection in first trimester of pregnancy is an area of increasing focus, and its adverse effects on pregnancy outcome are increasingly recognised. First-trimester infection is common and frequently acquired prior to conception. Although newer rapid diagnostic tests still have limited sensitivity, they may be useful in detection of early pregnancy malaria for treatment. Artemisinin-based combination therapies are efficacious in later pregnancy but have yet to be recommended in first trimester because of limited safety data. In Africa, intermittent preventive treatment in pregnancy (IPTp) with monthly sulfadoxine-pyrimethamine improves pregnancy outcomes, but sulfadoxine-pyrimethamine resistance is worsening. The alternative, IPTp with dihydroartemisinin-piperaquine, has greater antimalarial efficacy, but does not appear to improve pregnancy outcomes, because sulfadoxine-pyrimethamine has poorly understood nonmalarial benefits on birthweight.

SUMMARY

Novel IPTp regimens must be combined with interventions to strengthen protection from malaria infection acquired before and in early pregnancy.

Drugs for Intermittent Preventive Treatment of Malaria in Pregnancy: Current Knowledge and Way Forward

Malaria infection during pregnancy is an important driver of maternal and neonatal health in endemic countries. Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended for malaria prevention at each scheduled antenatal care visit, starting at the second trimester, in areas of high and moderate transmission. However, the increased resistance to SP in some endemic areas challenges its effectiveness. Furthermore, SP is contraindicated in the first trimester of pregnancy and in HIV-infected women on co-trimoxazole prophylaxis due to potential drug–drug interactions. Thus, in recent last decades, several studies evaluated alternative drugs that could be used for IPTp. A comprehensive literature review was conducted to summarize the evidence on the efficacy and safety of antimalarial drugs being evaluated for IPTp. Chloroquine, amodiaquine, mefloquine and azithromycin as IPTp have proven to be worse tolerated than SP. Mefloquine was found to increase the risk of mother-to-child transmission of HIV. Dihydroartemisin-piperaquine currently constitutes the most promising IPTp drug alternative; it reduced the prevalence of malaria infection, and placental and clinical malaria in studies among HIV-uninfected women, and it is currently being tested in HIV-infected women. Research on effective antimalarial drugs that can be safely administered for prevention to pregnant women should be prioritized. Malaria prevention in the first trimester of gestation and tailored interventions for HIV-infected women remain key research gaps to be addressed.

Gender difference in the incidence of malaria diagnosed at public health facilities in Uganda

BACKGROUND

Routine malaria surveillance data in Africa primarily come from public health facilities reporting to national health management information systems. Although information on gender is routinely collected from patients presenting to these health facilities, stratification of malaria surveillance data by gender is rarely done. This study evaluated gender difference among patients diagnosed with parasitological confirmed malaria at public health facilities in Uganda.

METHODS

This study utilized individual level patient data collected from January 2020 through April 2021 at 12 public health facilities in Uganda and cross-sectional surveys conducted in target areas around these facilities in April 2021. Associations between gender and the incidence of malaria and non-malarial visits captured at the health facilities from patients residing within the target areas were estimated using poisson regression models controlling for seasonality. Associations between gender and data on health-seeking behaviour from the cross-sectional surveys were estimated using poisson regression models controlling for seasonality.

RESULTS

Overall, incidence of malaria diagnosed per 1000 person years was 735 among females and 449 among males (IRR = 1.72, 95% CI 1.68-1.77, p < 0.001), with larger differences among those 15-39 years (IRR = 2.46, 95% CI 2.34-2.58, p < 0.001) and over 39 years (IRR = 2.26, 95% CI 2.05-2.50, p < 0.001) compared to those under 15 years (IRR = 1.46, 95% CI 1.41-1.50, p < 0.001). Female gender was also associated with a higher incidence of visits where malaria was not suspected (IRR = 1.77, 95% CI 1.71-1.83, p < 0.001), with a similar pattern across age strata. These associations were consistent across the 12 individual health centres. From the cross-sectional surveys, females were more likely than males to report fever in the past 2 weeks and seek care at the local health centre (7.5% vs. 4.7%, p = 0.001) with these associations significant for those 15-39 years (RR = 2.49, 95% CI 1.17-5.31, p = 0.018) and over 39 years (RR = 2.56, 95% CI 1.00-6.54, p = 0.049).

CONCLUSIONS

Females disproportionately contribute to the burden of malaria diagnosed at public health facilities in Uganda, especially once they reach childbearing age. Contributing factors included more frequent visits to these facilities independent of malaria and a higher reported risk of seeking care at these facilities for febrile illnesses.