Personal protection Aedes — DTM&H MCQ

Correct answer: B — Use repellent and long sleeves during daytime

D) Use repellent and long sleeves during daytime is correct. Zika is transmitted by Aedes aegypti and Aedes albopictus, which are day biting and crepuscular mosquitoes, so protection must be maintained throughout daylight hours using DEET or equivalent repellent, permethrin treated clothing, and long sleeves/trousers rather than being confined to sleeping hours. NaTHNaC/UKHSA travel health guidance for pregnant travellers to Zika affected areas explicitly emphasises scrupulous bite avoidance during both daytime and night time because of this vector behaviour. Since there is no vaccine or chemoprophylaxis for Zika, personal protective measures matched to the vector's biting pattern are the only effective intervention, making this the discriminating and correct answer. Why the other options are wrong: A. Rely on bed nets at night: Nets only protect during sleeping hours and are ineffective against Aedes mosquitoes, which feed predominantly by day, leaving the traveller unprotected when risk is highest. C. Take chloroquine weekly: Chloroquine is antimalarial prophylaxis targeting Plasmodium species transmitted by night biting Anopheles mosquitoes; it has no activity against the Zika flavivirus. E. Avoid freshwater swimming: This measure relates to schistosomiasis avoidance, not Zika, which is transmitted by mosquito bites rather than water contact. D. Take praziquantel before travel: Praziquantel is treatment for schistosomiasis, an unrelated helminth infection, and has no role in arbovirus prevention. Key point: Because Zika's Aedes vectors bite mainly by day, effective prevention requires continuous daytime use of repellent and covering clothing rather than night time measures alone.

Reference: NaTHNaC TravelHealthPro, Zika virus: Evaluating the risk to individual travellers, 2024, https://travelhealthpro.org.uk/factsheet/5/zika-virus-evaluating-the-risk-to-individual-travellers