Dengue fever

Dengue fever (also known as break bone fever) is a severe, flu-like viral illness that affects infants, young children and adults, but seldom causes death. It is transmitted by the bite of an infected mosquito, Aedes mosquitoes being the type most commonly associated with dengue fever. This type of mosquito tends to bite more during the daytime and at dawn and dusk. It is found commonly throughout the tropics and subtropics and is endemic in about 100 countries. 

Clinical Features
The illness is generally milder in children, more severe in adults. The typical illness is unpleasant with fever, chills, headache, backache and prostration (extreme exhaustion). The illness can typically last up to ten days. Full recovery is usual.

In certain circumstances, the disease may progress to dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS) both of which can be fatal. These are however, rare in travellers to endemic areas, these complication being more common in people who live in an area affected by Dengue and have been repeatedly exposed to the virus. 

Dengue fever cannot be prevented by vaccination or medicine - the only way to reduce the risk of being infected is by avoiding mosquito bites. The incubation period of dengue fever is generally 4 to 7 days following being bitten.

Dengue has increased considerably on the last few decades, particularly in urban and semi-urban areas. WHO now estimated that there might be as many as 50 million cases worldwide each year. Dengue is a notifiable disease in Ireland.

Prevention and Control
At present, the only method of controlling or preventing dengue and DHF is to combat the mosquitoes that carry the virus. The mosquito responsible tends to breed primarily in containers that can hold stagnant water such as earthenware jars, metal drums and concrete cisterns used for domestic water storage, as well as discarded plastic food containers, used automobile tyres and other items that collect rainwater. It can also breed in natural habitats such as tree holes and other places where water collects.

Control measures in affected countries have been largely directed at destroying habitats where mosquitoes might lay their eggs and the use of insecticide to directly kill mosquitoes and their larvae. Recently the mosquito responsible for carrying Dengue, Aedes Albopictus has become established in the Mediterranean basin, in parts of Spain, the French Riveria, Italy and the Adriatic coast and parts of Greece (see here for up to date maps from ECDC).

Protection for Travellers
The best way for travellers to endemic areas to avoid dengue fever is to avoid being bitten by mosquitoes. The list below highlights the most appropriate preventive measures.

Time:  As dengue is associated with a day-biting mosquito; precautions to reduce bites should be taken at all times during the day, and at dawn and dusk. 

Risky areas: Avoid areas where mosquitoes are likely to be found, i.e. near water including ponds, outdoor swimming pools, lakes and marshes.

Use mosquito repellents: Spray onto exposed skin whenever you are in an area where mosquitoes may be present. Repellents applied to clothing, shoes, tents, mosquito nets and other gear will enhance protection. Your local pharmacist can advise you on the most suitable preparation to use.

Dress safely: If in areas where mosquitoes are likely, wear long sleeves, long trousers, socks and closed shoes.

Indoors: Mosquito bites can be reduced by air conditioning, insect-proof screens on windows and doors and spraying the room with insecticide.

Mosquito nets: Bed nets and cot nets can be used if necessary, as an additional precaution.

Information on protecting yourself and your family against biting mosquitoes is available on the HPSC website.

Where can I get further information on dengue?

European Centre for Disease Prevention and Control

World Health Organization

Centers for Disease Control and Prevention, US

Updated: 28 August 2012