Applied Evidence

Another risk to US travelers—malaria

Author and Disclosure Information

To individualize preventive measures, rely on reported risk data for specific destinations, planned activities, and patient comorbidities.




› Assess the need for nonpharmacologic, behavioral interventions and for chemoprophylaxis based on a destination’s relative risk to travelers, planned and potential activities, and patient comorbidities. B
› Choose an antimalarial medication based on knowledge of area-specific drug effectiveness or resistance patterns, trip duration, drug cost, tolerance for adverse effects, and comorbidities. C
› Presume a diagnosis of malaria until proven otherwise in any traveler who is febrile after returning from a malaria-endemic region. C

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

Although malaria was eradicated as an endemic disease in the United States in the early 1950s,1 it still returns yearly in approximately 1500 individuals who travel to foreign countries2—most of whom neglected to use prophylactic measures or use them properly.3 In more than 60 documented cases, these infected individuals have been the source of local transmission in their communities.2 To reduce the individual and public health risks associated with malaria, this article focuses on steps that international travelers can take to limit their risk of the disease.

What travelers need to know

In 2013, more than 61.5 million residents of the United States traveled abroad, approximately 30% of whom visited malaria-endemic regions: Mexico and equatorial nations in Central and South America; Africa; the Middle East; and South, East, and Southeast Asia.4 Counseling on appropriate preventive measures fits the Medical Home concept of comprehensive, preventive, patient-centered care, and pre-travel consultation—including a review of health data and itineraries, and patient education—can be a team-based effort.5

Begin your planning for malaria prophylaxis by assessing your patient’s individual risk. Key variables are a patient’s detailed itinerary, a credible and current source of information on location-specific malaria prevalence, personal risk factors, and risk tolerance. Shared decision-making is vital and enhances adherence to the prescribed regimen.

Endemicity varies regionally. Without chemoprophylaxis, risk of infection ranges from more than 20% in Papua New Guinea to 0.01% in Central America, with wide exposure risk variations likely, even within regions.6 Travel to areas of high endemicity requires more aggressive malaria prevention strategies than travel to low-endemicity regions.

Risk of exposure is lower with short visits,7 business-only travel, urban-only stays in some countries, day trips to endemic areas,7 and travel during seasons with lower mosquito burden. Likewise, travelers staying in a hotel with sealed windows will face lower nighttime Anopheles mosquito exposure. In these cases, nonpharmacologic measures alone may be appropriate.

Those at particularly high risk for complicated or lethal malarial infection are children, pregnant women, elderly individuals, and immunocompromised patients.7 Assess risk by reviewing a traveler’s itinerary and considering location-specific malaria prevalence, personal risk factors such as comorbidities, and risk tolerance.In addition to counseling high-risk patients about prophylactic measures, consider advising against travel in certain circumstances. Among those at highest risk for acquiring malaria are immigrants and refugees traveling to their ancestral homelands to visit friends and relatives (VFR).2 Many VFR travelers fail to take appropriate prophylactic measures when “going home.”8 A significant number of cases of travel-acquired malaria occurs in VFR children.9

Individualizing prevention directives

The mainstays of malaria prevention include nonpharmacologic and behavioral interventions, as well as chemoprophylaxis. Most cases of malaria in travelers returning to the United States result from the improper implementation of prophylactic measures.3 Discussing individual risk with travelers is an easy way to bolster adherence to malaria prevention measures, and some evidence suggests it is effective10 (strength of recommendation [SOR]: C). Other limited studies have also shown that malaria education can improve knowledge about malaria transmission and increase the likelihood that preventive measures will be used.11,12

Recommend nonpharmacologic measures even for those using chemoprophylaxis

Nonpharmacologic interventions such as sleeping under permethrin-treated bednets, wearing long sleeves and full-length pants, treating clothes with permethrin, and applying DEET (N,N-diethyl-meta-toluamide) to exposed skin are effective and have the added benefit of preventing non-malarial arthropod-borne diseases4 (SOR: B). Studies have shown that, compared with sleeping without nets, the use of insecticide treated-nets can reduce child mortality by 17% and the incidence of uncomplicated malarial episodes by 50%.13 In areas with malaria transmission, 10% to 30% DEET—used alone or in combination with permethrin-treated clothing— can reduce bite load, although the American Academy of Pediatrics recommends against using DEET in children younger than 2 months of age.14,15

Using these measures in combination from dusk to dawn, when Anopheles mosquitoes are active, has been shown to be effective, although randomized, controlled studies are lacking.16 Remaining indoors during these peak biting periods is also advisable. In certain areas, and with the right itinerary, the traveler may only need to employ nonpharmacologic methods of preventing malarial infection. Recommend them to all patients traveling to malarial regions, even to individuals using pharmacologic prophylaxis.

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