Houston-area malaria cases linked to immigration, travel

All patients included in a recent study involving 21 children with severe malaria and 83 children with uncomplicated malaria, were either recent immigrants or had traveled outside of the United States prior to presenting with symptoms.

“A multifaceted approach will be necessary to prevent imported malaria,” the researchers wrote.

They performed retrospective chart reviews from patients at four tertiary pediatric-care hospitals in Houston to study the epidemiology of malaria cases in the surrounding area from 1994 to 2007. The researchers examined the medical records of 104 children aged 19 days to 17.4 years who had discharge diagnoses of malaria as well as positive malaria smears.

Among the reviewed cases, 43 children were immigrants and 61 had recently traveled outside the United States. Ninety percent of these children had traveled to West Africa, 5% to Central America and 5% to Asia — all of which are malaria-endemic regions. For 42 children, travel was vacation-related with the intent to visit the family’s country of origin.

Results also revealed that the following factors were more often associated with severe as opposed to uncomplicated malaria:

Vacation-related travel (67% vs. 27%).
Female sex (67% vs. 39%).
Birth in the United States (64% vs. 35%).
Shorter travel duration (median, 23.5 days vs. 35 days).
Shorter duration between return from travel and appearance of symptoms (median, 13 days vs. 25 days).
History of vomiting (81% vs. 57%).
Higher peak parasitemia (median, 11.2% vs. 1.5%).
Hepatomegaly (71% vs. 39%) and heart murmur (67% vs. 42%) accompanying symptoms.

The researchers identified 47 children with documentation of malaria prophylaxis and 17 who had pretravel visits with medical providers. Five of nine children visiting relatives and friends engaged in pretravel consultations. However, only eight of 47 had documentation of prophylaxis appropriate for the region to which they were traveling.

Stricter adherence to prophylaxis recommendations might have prevented more U.S.–born children from contracting the disease abroad, the researchers noted. However, prophylaxis did not play a role in the severity of disease in children with malaria.

“For children leaving the United States to visit malaria-endemic regions, efforts must raise awareness of the risk of contracting malaria and of the need for appropriate prophylaxis, particularly for travelers to West Africa,” the researchers wrote. They encourage maintaining a “high index of suspicion” for malaria in any febrile child who has returned to the United States from this region, particularly during the summer months and winter holiday season. – by Melissa Foster

Oramasionwu GE. Pediatr Infect Dis J. 2010;29:28-32.

The results of this study reinforce the importance of following prophylaxis guidelines for travelers to areas in which there is a risk for acquiring malaria. It is also important to know what the proper medications are for malaria prophylaxis because they may vary depending on the destination and susceptibility to potential adverse effects. It is of interest that severe malaria was more common in travelers from the United States. However, this is not really surprising since people who live in endemic areas may have some degree of immunity from repeated exposure.

– Eugene Shapiro, MD
Infectious Diseases in Children Editorial Board