What are the recommendations for preventing and treating malaria in the Rio Grande Valley (RGV)?

Malaria Prevention and Treatment in the Rio Grande Valley (RGV)

There is no endemic malaria transmission in the Rio Grande Valley, and therefore no specific prevention or treatment recommendations are needed for residents who have not traveled to malaria-endemic regions. 1

Epidemiology of Malaria in the United States

Malaria is not endemic to the Rio Grande Valley or any part of the United States. The approximately 2,000 cases diagnosed annually in the US occur almost exclusively in travelers returning from malaria-endemic regions 1:

• 79% of US malaria cases are caused by P. falciparum
• 11.2% are caused by P. vivax
• Over 80% of US malaria cases are acquired in Africa
• 71.7% of US residents diagnosed with malaria had not taken appropriate chemoprophylaxis

Recommendations for RGV Residents Traveling to Malaria-Endemic Areas

Pre-Travel Prevention

1. Chemoprophylaxis Selection:

   • For travel to areas without chloroquine-resistant P. falciparum: Weekly chloroquine 2
   • For travel to areas with chloroquine-resistant P. falciparum: Mefloquine or atovaquone-proguanil 2, 3
   • Alternative for short-term travelers who cannot take mefloquine: Daily doxycycline 2

2. Timing of Chemoprophylaxis:

   • Begin 1-2 weeks before travel (except doxycycline, which can begin 1-2 days before) 2
   • Continue during travel and for 4 weeks after leaving malarious areas (except for atovaquone-proguanil, which can be stopped 7 days after return) 2, 3

3. Personal Protection Measures 2:

   • Use DEET-containing insect repellent on exposed skin
   • Stay in well-screened areas
   • Use mosquito nets when sleeping
   • Wear clothing that covers most of the body
   • Use pyrethrum-containing flying-insect spray in living/sleeping areas
   • Apply permethrin to clothing for additional protection

Treatment for RGV Residents Returning with Malaria

Diagnostic Approach

Any RGV resident returning from a malarious area who develops fever or flu-like symptoms should immediately seek medical care and inform providers about their travel history 2, 1.

Treatment Recommendations

1. For uncomplicated P. falciparum malaria:

   • First-line: Artemisinin-based combination therapy 1
   • Alternative when artemisinin unavailable: Atovaquone-proguanil (4 tablets once daily for 3 days) 3, 1

2. For chloroquine-sensitive P. falciparum (acquired in Haiti, Dominican Republic, Central America west of Panama Canal, Middle East, or Egypt):

   • Chloroquine remains effective 2, 1

3. For P. vivax, P. ovale, P. malariae, and P. knowlesi:

   • Chloroquine or artemisinin-based combination therapy 1
   • For P. vivax and P. ovale: Additional treatment with primaquine or tafenoquine needed to eliminate liver stage 1

4. For severe malaria:

   • Intravenous artesunate is first-line therapy 1
   • Severe malaria is a medical emergency with 0.3% mortality rate in the US 1

Special Considerations

Pregnant Women

Pregnant women traveling to malaria-endemic areas are at higher risk for severe malaria and must use appropriate chemoprophylaxis 4. Mefloquine is generally considered safe in pregnancy 2.

Renal Impairment

Atovaquone-proguanil should not be used for malaria prophylaxis in patients with severe renal impairment (creatinine clearance <30 mL/min) 3.

Common Pitfalls

1. Failure to take prophylaxis: Most US malaria cases occur in people who did not take appropriate chemoprophylaxis 1, 4.

2. Delayed diagnosis: Malaria can be fatal if not diagnosed and treated promptly. Symptoms can develop as early as 8 days after exposure or as late as several months after return 2.

3. Improper DEET use: To minimize adverse reactions, apply DEET sparingly only to exposed skin/clothing, avoid high concentrations in children, and wash treated skin after coming indoors 2.

4. Inadequate duration of prophylaxis: Continuing prophylaxis after return is essential as symptoms can develop weeks to months after exposure 2.