Congenital Malaria Due to Plasmodium Vivax Mimicking Late-Onset Neonatal Sepsis in a Non-Endemic Area: Case Report

Malaria is a disease transmitted mainly through the bite of Anopheles mosquitoes, which inoculate Plasmodium sporozoites into the human host. Congenital malaria rarely occurs, via vertical transmission of the parasite’s blood forms in utero or during delivery. We report the case of a Venezuelan pregnant woman with Plasmodium vivax malaria treated with chloroquine and primaquine in the first trimester, before pregnancy was confirmed. After pregnancy diagnosis, she was followed at a tertiary hospital in southern Brazil, a region without parasite circulation. She experienced a recurrence of P. vivax and received chloroquine (loading dose for 3 days) and weekly prophylaxis; primaquine was postponed due to contraindication in pregnancy. She remained asymptomatic with negative tests until vaginal delivery, when the newborn had Apgar scores of 3/8 and required resuscitation, but then stabilized clinically. Initial tests such as complete blood count and thick smear for parasites were normal, and the infant was discharged without symptoms. At 21 days of life, the newborn returned with intermittent fever, hepatosplenomegaly, severe anemia, and thrombocytopenia. Late-onset neonatal sepsis was considered, but based on the clinical and epidemiological history, direct testing for Plasmodium and a rapid test were performed, confirming severe P. vivax infection in a non-endemic region. The mother and the newborn were tested for G6PD deficiency, and both results were negative. The case was reported to surveillance authorities, and treatment with intravenous artesunate was initiated, followed by oral artemether-lumefantrine, with favorable evolution, laboratory normalization, and hospital discharge. The mother completed treatment with chloroquine and primaquine 40 days after delivery. The baby was followed as an outpatient until 18 months of age, with adequate neuropsychomotor development. Although rare, congenital malaria should be considered even in non-endemic areas, especially in pregnant women with a migratory history. The clinical picture can mimic neonatal sepsis and other congenital infections, thereby delaying diagnosis. Early suspicion is essential to ensure appropriate treatment. It is emphasized that, in congenital P. vivax malaria in a non-endemic region, infection results from blood forms without hepatic hypnozoites, making primaquine unnecessary for the newborn. Follow-up is important given the risk of alterations in child development.