Management and Prevention of Insect‑Borne Diseases in Travelers to Costa Rica

Epidemiology

Aedes mosquito bites constitute the highest clinical risk in Costa Rica, with dengue fever responsible for approximately 5 % of febrile illnesses among travelers returning from Latin America. 1

Aedes aegypti is a day‑biting mosquito that transmits dengue virus throughout Costa Rica. 2
Rickettsia rickettsii carried by local ticks can cause Rocky Mountain spotted fever; infection typically follows prolonged tick attachment (>24 h). 2

Dengue infection presents after an incubation of 4–8 days (range 3–14 days) with fever, headache, retro‑orbital pain, severe myalgia, arthralgia (often back pain), and a maculopapular rash. 2
Rickettsial infections commonly manifest with fever, headache, myalgia, and an inoculation eschar; a rash occurs in fewer than 50 % of cases. 2

Dengue is confirmed by PCR when performed ≤ 5–7 days after symptom onset, or by IgM capture ELISA when performed > 5–7 days. 2
Empiric doxycycline therapy is recommended for suspected tick‑borne rickettsial infection without awaiting serologic confirmation, given a reported untreated mortality of up to 32 %. 2

Dengue: Provide supportive care with oral hydration and acetaminophen; avoid NSAIDs because of bleeding risk. Monitor for warning signs of hemorrhagic fever (e.g., thrombocytopenia, plasma leakage). 2
Rickettsial infection: Initiate doxycycline as first‑line therapy; fluoroquinolones or azithromycin may be used as alternatives. 2
Simple insect‑bite reactions: Apply topical corticosteroids for localized pruritus. 3

Apply a DEET‑based repellent containing 20 %–50 % concentration to exposed skin; use sparingly, keep away from children’s hands, avoid application to wounds or irritated skin, and wash off after entering indoor environments. [4][5]
Wear long‑sleeved shirts and long pants during dawn and dusk, especially in areas with malaria risk, although dengue vectors bite primarily during daylight hours. 6
Treat clothing with permethrin to provide additional protection against mosquito and tick bites. 4
Use pyrethroid‑containing indoor insect spray in living and sleeping areas to reduce flying insect exposure. 7

Any fever developing 3–14 days after mosquito exposure should prompt immediate evaluation for dengue, even in the absence of rash. 2
NSAIDs must be avoided in suspected dengue due to the potential for hemorrhagic complications; acetaminophen is the preferred analgesic. 2
Delay in administering doxycycline for suspected rickettsial infection increases mortality risk; empirical treatment should not await laboratory confirmation. 2