Plasmodium falciparum malaria in pregnancy: a review

Fever of unknown origin in pregnancy: the need for a full history

A 26-year-old woman with 29 weeks gestation presented with headache, photophobia and fever. She had deranged liver function tests and low platelets on admission. Blood film, performed to look for haemolysis, revealed she had Plasmodium vivax malaria, despite not having travelled to an endemic malaria area for over 1 year. The diagnosis was confirmed on PCR test performed in the HPA malaria reference laboratory in London and she was treated with chloroquine. She delivered a healthy baby at 33+3 weeks gestation, and once the patient and the baby had both tested negative for glucose-6-phospate dehydrogenase deficiency, she was given primaquine to clear the hypnozoite phase in the liver. This case highlights the importance of an extended travel history in a patient with fever of unknown origin and the difficulties of treating non-falciparum malaria in pregnancy.

The effect of malarial infection on maternal-fetal outcome in Ecuador

OBJECTIVE

To describe maternal and fetal outcome among pregnancies complicated with malarial infection.

METHODS

Charts of pregnancies complicated with malarial infection were reviewed. Parasital etiology and maternal/fetal data was analyzed.

RESULTS

During the year 2001, at the Enrique C. Sotomayor Obstetrics and Gynecology Hospital, Guayaquil-Ecuador, 80 pregnancies complicated with malarial infection were admitted for treatment. This rendered an incidence of 2.1 per 1,000 live births (80/37,579). Mean maternal age was 25.2 +/- 6.7 years and the 19-29 age group was the most frequently affected (50%). On admittance, fever, chills, jaundice and anemia was present in 97.5%, 78.8%, 38.8% and 60% respectively. Falciparum was the most frequently presenting species (56.3%). Patients admitted at < 20 weeks gestation (n = 17) had a 76.5% and 82.4% abortion and adverse fetal outcome rate respectively. Among those admitted at 20-36 weeks (n = 55) the rates for preterm birth, intrauterine fetal death, low birthweight (LBW) and small-for-gestational age (SGA) were 34.5%, 11%, 40.8% and 48.9% respectively. Among patients admitted > 36 weeks, 87.5% (7/8) ended in a live term delivery. Adolescents presented a higher rate of anemia and SGA neonates. The overall (n = 80) abortion, preterm delivery and intrauterine fetal demise rates were 16.3%, 25% and 8.8% respectively. Chloroquine effectively treated 98.8% of cases and there was one maternal death due to falciparum infection.

CONCLUSIONS

In this Ecuadorian population, malarial infection complicating gestation was associated to adverse maternal-fetal outcome, which was more evident among teenagers and pregnancies presenting malaria at an earlier gestational age.

Outcomes of imported malaria during pregnancy within Venezuelan states: implications for travel advice

Prevention of malaria in pregnant women is an utmost priority because the disease can cause serious maternal and neonatal complications. Maternal complications include marked anemia, increased risk of severe disease, and mortality, while the fetus or neonate is at risk of prematurity, anemia, and low birthweight. Pregnant women living in malaria endemic areas may be semiimmune to a particular Plasmodium spp. but when traveling to other regions, sometimes within their same country, where malaria epidemiology is different, may develop severe malaria complications. Here, we describe our experience in northeastern Venezuela associated with unfavorable outcomes of imported malaria cases among pregnant women who traveled to other Venezuelan regions with different malaria epidemiology. Travel medicine practitioners should be aware and educate their pregnant patients regarding the risk of malaria even when living in malaria endemic areas and traveling to other endemic areas such as occurs in Venezuela.

Studies on Plasmodium falciparum isotypic antibodies and numbers of IL-4 and IFN-gamma secreting cells in paired maternal cord blood from South West Cameroon

OBJECTIVES

In this study, the effect of maternal peripheral and placental Plasmodium falciparum parasitaemia on the level of antibody and cytokine immune responses in the neonate was investigated.

METHODS

Malaria parasites were detected by light microscopy. Levels of malaria-specific isotypic antibodies were measured in maternal and cord blood by indirect ELISA. The numbers of IFN-gamma and IL-4 cells produced by maternal/cord blood after in vitro stimulation were enumerated using the ELISPOT assay.

RESULTS

Malaria parasite rate of maternal, placental biopsy and cord blood was 32.8%, 33.7% and 7.8% respectively. Overall, ELISA seropositivity rates for P. falciparum-specific IgG, IgM, IgE and IgA in the maternal plasma samples were 71%, 85%, 29.3%, and 0% respectively, while those for the cord samples were 69%, 6.0%, 4.4% and 0% respectively. Mean IgM ELISA OD(405) values of neonates born from positive placentas, or whose mothers had peripheral malaria parasitaemia were higher than those who were parasite negative. The mean number of maternal cells producing IFN-gamma was higher (P=0.0001) than that of the paired cord samples. The mean number of IL-4 producing cells of neonates born of mothers who were positive (P<0.05) or from malaria-positive placentas (P<0.025) was higher than from those who were malaria negative. Neonates born of malaria-positive mothers or from parasitized placentas mounted predominantly Th2 type immune responses.

CONCLUSION

It appears from this study that neonates born from malaria-infected mothers or placentas may relatively be more susceptible to malaria attack during the first years of life.

Imported malaria at an inner-city hospital in the United States

BACKGROUND

More than 1000 cases of malaria are reported to the Centers for Disease Control and Prevention each year among travelers or immigrants.

METHODS

Retrospective study of patients with malaria seen at Grady Memorial Hospital in Atlanta, Georgia, between October 1988 and September 2000.

RESULTS

One hundred twenty-six cases of malaria were diagnosed at Grady Memorial Hospital during the study period. Fourteen patients had seen a physician prior to coming to Grady Memorial Hospital, and in 71% the diagnosis was missed. Half had recently immigrated and half recently traveled to an endemic area, yet only 22% of travelers took prophylaxis. Plasmodium falciparum was the most commonly identified species (52.4%), followed by Plasmodium vivax (23.9%). Seventy-two patients (57.1%) required hospitalization. Presenting symptoms included fever (94%), chills (56%), nausea/vomiting (38%), headache (26%), and abdominal pain (26%). Most patients were diagnosed correctly on the day of admission (79%). Twelve patients (16.7%) had severe malaria, and their complications included severe anemia (9.7%), acute renal failure (4.2%), bleeding and/or disseminated intravascular coagulation (4.2%), shock (2.8%), seizures (2.8%), and hypoglycemia (2.8%). One patient died, and two pregnant women had premature deliveries. Median hospital stay was 3.9 days. One third of the hospitalized patients with P vivax failed to receive primaquine, and in 15% of patients with P falciparum, the treatment was considered to be inappropriate.

CONCLUSIONS

Although some patients with malaria have a benign course and a good outcome, many patients require hospitalization, and some have severe complications. Increased efforts are needed to educate travelers about the need for prophylaxis.

Safety of mefloquine and other antimalarial agents in the first trimester of pregnancy

BACKGROUND

Safe and effective antimalarials are required to protect pregnant women from the harmful effects of malaria.

METHODS

Data were collected from two separate prospective cohorts to ascertain the safety of chloroquine-proguanil, sulfadoxine-pyrimethamine (SP), and mefloquine taken in the first trimester of pregnancy.

RESULTS

In a traveler cohort of 236 pregnant women, spontaneous abortions were reported in 7.6% of 99 women taking chloroquine-proquanil, 0% of 19 taking sulfadoxine-pyrimethamine, and 9.1% of 118 women taking mefloquine. Anomalies were identified in 1.7%, 0% and 0% of the same cohort, respectively. Differences in rates of adverse outcomes between the three groups were not statistically significant. In a pharmaceutical database of 331 and 153 women exposed to mefloquine and SP, respectively, the overall rate of abnormal outcomes (spontaneous abortions plus fetal anomalies) was not significantly different (p=.29). Spontaneous abortions were significantly higher with mefloquine than SP (9.1% and 2.6%, respectively; p=.01), but the higher rate was comparable to background rates (7%-11%). Fetal anomalies in the mefloquine group (4.8%) were lower than the SP group (7.8%), but this was statistically not significant (p=.19), and was comparable with the background rate of 4.6% (p=.84). However, mefloquine exposure resulted in a significantly higher rate of therapeutically induced abortions, undertaken for perceived risk to the fetus, compared with SP (p<.0001).

CONCLUSION

From the clinical data available, there is no indication that the risk of taking mefloquine in the first trimester of pregnancy is greater than that from any of the other antimalarials studied and the risk is considerably lower than that associated with falciparum malaria.

Malaria Elicits Type 1 Cytokines in the Human Placenta: IFN-γ and TNF-α Associated with Pregnancy Outcomes

Pregnant women, especially primigravidas, are highly susceptible to malaria infection, resulting in maternal anemia and low birth weight infants. Because circulating parasitemia is rare in the newborn, the cause of poor fetal outcomes has been unclear. We measured cytokine concentrations in placentas collected from women delivering in urban hospitals in malaria-holoendemic or nonendemic areas of Kenya. Normal placentas displayed a bias toward type 2 cytokines; type 1 cytokines IFN-γ and IL-2 were absent in placentas not exposed to malaria but present in a large proportion of placentas from a holoendemic area. TNF-α and TGF-β concentrations were significantly higher, and IL-10 concentrations significantly lower, in placentas from the holoendemic area. Among primigravidas, placental TNF-α concentrations were significantly higher in the presence of severe maternal anemia, and both IFN-γ and TNF-α were significantly elevated when a low birth weight, rather than normal weight, infant was delivered. We conclude that maternal malaria decreases IL-10 concentrations and elicits IFN-γ, IL-2, and TNF-α in the placenta, shifting the balance toward type 1 cytokines. This is the first demonstration that these placental cytokine changes are associated with poor pregnancy outcomes in humans.

Malaria in pregnancy

This review summarizes the epidemiology, clinical course, and diagnosis of malaria. The influence of infection during pregnancy upon maternal and neonatal anemia, stillbirth, preterm labor, low birth weight, and congenital malaria is discussed. Options for treatment and prophylaxis during pregnancy are presented.

The safety of antimalarial drugs in pregnancy

Alternative drugs to chloroquine are required to prevent the deleterious effects of malaria in pregnancy. Fear of potential toxicity has limited antimalarial drug use in pregnancy. Animal toxicity studies have documented teratogenicity when antimalarials are administered at high dosages. Excepting the tetracyclines, there is no evidence to suggest that, at standard dosages, any of the antimalarial drugs are teratogenic. Primaquine is not recommended because of the potential risk of haemolytic effects in the fetus. Rates of spontaneous abortion and birth defects were comparable in pregnant women taking mefloquine, compared with chloroquine-proguanil, or pyrimethamine-sulfadoxine prophylaxis, in the first trimester of pregnancy. Standard doses of quinine do not increase the risk of abortion or preterm delivery. Therapeutic mefloquine does not provoke hypoglycaemia. There is no evidence in the literature to support the hypothetical risk of kernicterus in the newborn, following exposure to antimalarial drugs containing sulphonamides or sulphones prior to delivery. Documentation of the safety of doxycycline, halofantrine, and the artemisinin derivatives in the treatment of malaria in pregnant women is currently limited.

The pregnant traveler

The pregnant traveler should seek current and specific advice from experts even if she is traveling to a nearby wilderness area. This advice will make a significant contribution to the safety and health of the pregnant woman and her future newborn. There are many situations, for example, travel to Kenya, the Andes, or the Amazon basin in Peru, where the pregnant traveler is best advised to stay at home, or to defer the trip.