Another risk to US travelers—malaria

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Applied Evidence

Another risk to US travelers—malaria

J Fam Pract. 2014 November;63(11):E1-E7

Winston Liaw, MD

Sarah Coleman, MD

Andrew Bazemore,  MD, MPH

Mark K. Huntington, MD, PhD

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

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References

1. Mali S, Steele S, Slutsker L, et al; Centers for Disease Control and Prevention (CDC). Malaria surveillance - United States, 2008. MMWR Surveill Summ. 2010;59:1-15.

2. Centers for Disease Control and Prevention. Malaria facts. Centers for Disease Control and Prevention Web site. Available at: www.cdc.gov/malaria/about/facts.html. Accessed September 29, 2014.

3. Huntington MK. Healthy people, malaria and South Dakota. S D Med. 2012;65:297-300.

4. Office of Travel and Tourism Industries. U.S. citizen travel to international regions, 2013. Office of Travel and Tourism Industries Web site. Available at: http://travel.trade.gov/view/m-2013-O-001/index.html. Accessed September 29, 2014.

5. Bazemore AW, Huntington M. The pretravel consultation. Am Fam Physician. 2009;80:583-590.

6. Bradley DJ, Warhurst DC, Blaze M, et al. Malaria imported into the United Kingdom in 1996. Euro Surveill. 1998;3:40-42.

7. Arguin PM, Tan KR, et al; Centers for Disease Control and Prevention. Infectious diseases related to travel. Centers for Disease Control and Prevention Web site. Available at: http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-to-travel/malaria. Accessed October 15, 2014.

8. Pavli A, Maltezou HC. Malaria and travellers visiting friends and relatives. Travel Med Infect Dis. 2010;8:161-168.

9. Stäger K, Legros F, Krause G, et al. Imported malaria in children in industrialized countries, 1992-2002. Emerg Infect Dis. 2009;15:185-191.

10. Hartjes LB, Baumann LC, Henriques JB. Travel health risk perceptions and prevention behaviors of US study abroad students. J Travel Med. 2009;16:338-343.

11. Kishore J, Gupta VK, Singh SV, et al. Impact of health education intervention on knowledge and community action for malaria control in Delhi. J Commun Dis. 2008;40:183-192.

12. Chirdan OO, Zoakah AI, Ejembi CL. Impact of health education on home treatment and prevention of malaria in Jengre, North Central Nigeria. Ann Afr Med. 2008;7:112-119.

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14. Centers for Disease Control and Prevention. Fight the bite for protection from malaria: Guidelines for DEET insect repellent use. Centers for Disease Control and Prevention Web site. Available at: http://www.cdc.gov/malaria/toolkit/DEET.pdf. Accessed September 29, 2014.

15. American Academy of Pediatrics. Safety & prevention. Healthychildren.org Web site. Available at: http://www.healthychildren. org/English/safety-prevention/at-play/Pages/Insect-Repellents. aspx. Accessed September 29, 2014.

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17. Boggild AK, Parise ME, Lewis LS, et al. Atovaquone-proguanil: report from the CDC expert meeting on malaria chemoprophylaxis (II). Am J Trop Med Hyg. 2007;76:208-223.

18. Tan KR, Magill AJ, Parise ME, et al; Centers for Disease Control and Prevention. Doxycycline for malaria chemoprophylaxis and treatment: report from the CDC expert meeting on malaria chemoprophylaxis. Am J Trop Med Hyg. 2011;84:517-531.

19. Hill DR, Baird JK, Parise ME, et al. Primaquine: report from CDC expert meeting on malaria chemoprophylaxis I. Am J Trop Med Hyg. 2006;75:402-415.

20. Steffen R, Fuchs E, Schildknecht J, et al. Mefloquine compared with other malaria chemoprophylactic regimens in tourists visiting east Africa. Lancet. 1993;341:1299-1303.

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PRACTICE RECOMMENDATIONS

› 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,¹it still returns yearly in approximately 1500 individuals who travel to foreign countries²—most of whom neglected to use prophylactic measures or use them properly.³In more than 60 documented cases, these infected individuals have been the source of local transmission in their communities.²To 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.⁴Counseling 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.⁶Travel 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,⁷business-only travel, urban-only stays in some countries, day trips to endemic areas,⁷and 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.⁷Assess 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).²Many VFR travelers fail to take appropriate prophylactic measures when “going home.”⁸A 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.³Discussing 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%.¹³In 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.¹⁶Remaining 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.