Dengue, Mosquitoes and Sandflies in Grenada: How to Avoid Bites

Mosquitoes in Grenada are less a nuisance than a health question, because the species that matters most, Aedes aegypti, carries dengue fever. It bites mainly during the day, especially in the early morning and late afternoon, which is exactly when visitors are sitting on verandas, walking to the beach or hiking to a waterfall.

Grenada has had periods of increased dengue in recent years, as has much of the Caribbean, and the Ministry of Health issues reminders whenever cases rise. Chikungunya swept through the region in 2014 and Zika in 2016. There is no malaria. Add the tiny sandflies that bite on some beaches at dusk, and it is worth knowing how to keep bites to a minimum.

Know your biters

Aedes aegypti is small and dark with white markings on its legs. It lives close to people, breeds in clean standing water in containers, and bites quietly around ankles and under tables. Because it bites by day, a mosquito net at night does little against it, though nets and screens still help with other species.

Night-biting mosquitoes, including Culex species, are the ones that whine in the bedroom. They are mostly an irritation rather than a dengue risk, and screens, fans and air conditioning deal with them.

Sandflies, called no-see-ums by many visitors, are tiny biting midges found on some beaches and mangrove edges, especially around sunset on calm evenings and in sheltered bays. The bites are itchy out of all proportion to the insect's size, and they are worst where there is little breeze. They do not transmit dengue. A breezy spot, long light clothing at dusk and repellent on exposed skin all help.

Repellents and habits that work

Use a proven ingredient. Repellents containing DEET (20 to 50 per cent), picaridin (also called icaridin), IR3535 or oil of lemon eucalyptus are the ones health agencies recommend. Pharmacies and supermarkets in Grenada stock several, but bring your preferred one if you are particular.

Apply it properly. Put sunscreen on first, let it settle, then apply repellent. Reapply after swimming or heavy sweating, which in Grenada means often. Cover ankles and the backs of legs, the favourite targets.

Dress for the hours that matter. Light-coloured long trousers and long sleeves in the early morning and late afternoon reduce bites considerably. Clothing treated with permethrin adds protection on hikes.

Use air movement. A ceiling or standing fan over a table or bed makes it hard for mosquitoes and sandflies to land. Many locals swear by sitting in the breeze rather than relying on sprays alone, and beach bars often place tables to catch the wind.

Sleep protected. Choose accommodation with screened windows or air conditioning, and use a net if the room has neither. Plug-in vaporisers and mosquito coils are widely sold, but coils should only be burnt outdoors or in well-ventilated spaces.

When mosquitoes are worst

Mosquito numbers follow the rain. The rainy season, roughly June to December, brings far more breeding sites, and numbers typically rise a week or two after heavy showers. The dry season from about January to May is calmer, though Aedes keeps breeding in household water storage all year, so dengue does not disappear in the dry months.

Location matters too. Gardens with lush planting, areas near streams and mangroves, and properties where water is stored in drums or tanks tend to have more mosquitoes. Breezy hillsides and beachfronts with steady trade winds usually have fewer. After hurricanes and major floods, when debris and damaged water storage leave pools everywhere, mosquito-borne illness often rises, which is part of why the Ministry of Health steps up vector control after storms.

Hikers should be especially careful in the rainforest around Grand Etang and on waterfall trails in St Andrew and St John, where shade and moisture keep mosquitoes active through the day.

Recognising dengue and what to do

Dengue usually starts four to ten days after an infected bite. Many cases are mild, but some become serious, and it is important to recognise when to see a doctor. Typical symptoms include:

• Sudden high fever, often with a severe headache and pain behind the eyes.
• Strong muscle and joint pains, which gave dengue its old nickname of breakbone fever.
• Nausea, vomiting, and sometimes a rash appearing a few days into the illness.
• See a doctor promptly for testing and advice; a blood test can confirm dengue and monitor platelet levels.
• Use paracetamol for fever and pain, and avoid aspirin and ibuprofen, which can increase bleeding risk in dengue.
• Drink plenty of fluids, including oral rehydration solution, and rest; dengue fatigue can linger for weeks.
• Keep using repellent while ill, because a mosquito that bites an infected person can pass dengue to others in the household.
• Seek urgent care at a hospital for severe abdominal pain, persistent vomiting, bleeding gums or nose, blood in vomit or stools, unusual drowsiness or restlessness, especially as the fever falls, which is when complications tend to appear.

Other biting and stinging creatures

Wasps. Paper wasps, known in parts of the Caribbean as Jack Spaniards, build nests under eaves, in fruit trees and in dense bush. Stings are painful and occasionally dangerous for people with allergies. Look before reaching into trees when picking fruit, and walk away calmly from a disturbed nest.

Centipedes. Large centipedes live in damp, dark places and occasionally come indoors, especially in the rainy season. Their bite is very painful but rarely serious in healthy adults. Shake out shoes, towels and clothes left on the floor, and check bedding in ground-floor rooms.

Ants. Several species of biting and stinging ants are common in gardens and on hiking trails. Avoid sitting directly on the ground in the bush, and check before putting a bag down beside a trail.

Allergies. Anyone with a known severe allergy to stings should carry two adrenaline auto-injectors, because replacement locally may not be immediate. Swelling of the face or throat, or difficulty breathing after a sting, is an emergency; use the injector and call 911.

Living here: stopping mosquitoes at home

Residents can reduce mosquito numbers dramatically by removing breeding sites around the house, which is what the Ministry of Health's vector control officers urge every time cases rise. Aedes aegypti needs only a bottle cap of clean water to breed, and it rarely flies more than a short distance from where it hatched, so the mosquitoes biting you were probably born in your yard or your neighbour's.

Once a week, tip out water from plant saucers, buckets, old tyres, coconut shells and anything else that collects rain. Scrub the inside of containers, because eggs stick to the walls and survive drying. Keep water drums and tanks tightly covered or screened, clean out roof gutters that hold water, and change water in pet bowls and vases often. Bromeliads and other plants that hold water in their leaves can be flushed regularly.

Vector control teams carry out inspections and fogging in communities during outbreaks. Fogging kills adult mosquitoes for a short time, but it does not replace clearing breeding sites, which is the only lasting solution.

Screens on windows and doors remain the most effective single investment for a home. Many older Grenadian houses were built for airflow with open louvres and no screens, so new residents renting such a property often add mesh screens, or at least use nets over beds and fans in each room.

Frequently asked questions