Dengue fever

What is dengue virus infection?

Dengue virus infection usually causes a severe ‘flu-like illness that rarely causes death. Dengue virus infection is spread by the bite of an infected mosquito. There are four different types of dengue virus and infection with any of the four will give life-long protection to that type but not to the other three types.

What are the symptoms of dengue virus infection?

An estimated three out of four people with dengue virus infection do not have symptoms at all. For those who have symptoms, dengue virus infection generally causes a severe flu-like illness that lasts between 2 and 10 days. The time between being infected with dengue virus and developing symptoms is usually between 3 and 14 days. Symptoms of dengue virus infection may be different depending on the age of the person infected.

In some cases, the disease may progress to dengue haemorrhagic fever (DHF) or dengue shock syndrome (DSS) both of which can cause death. DHF and DSS are rare and are more common in people who live in an area affected by dengue virus infection and have been infected with different types of the virus over time.

The most common symptoms of dengue virus infection include:

  • fever
  • chills
  • headache
  • backache
  • skin rash
  • extreme exhaustion

How is dengue virus infection spread?

Dengue virus infection is spread by the bite of an infected mosquito. The type of mosquito that spreads dengue virus infection bites during the daytime, and is most active at dawn and dusk. It is found in Asia, the Pacific, the Caribbean, the Americas and Africa and is common in about 100 countries. Dengue virus infection cannot be prevented by vaccination or medicine so the only way to reduce the risk of being infected is by avoiding mosquito bites.

Other less common possible forms of transmission include:

  • from mother to baby during pregnancy, childbirth and breastfeeding
  • from a blood transfusion, organ or tissue transplant
  • from a needlestick injury or laboratory accident

Dengue virus has been found in semen and vaginal fluids but sexual transmission has not yet been reported in people.

One case of dengue virus infection has been reported in a health care worker with no travel history to an affected area, but who was splashed in the face by blood from a patient infected with dengue.

Dengue virus infection is not spread by the following:

  • regular social contact
  • usage of communal household utensils
  • caring for someone with dengue virus infection

How is dengue virus infection spread from mother to baby?

It is currently thought that dengue virus infection may be transmitted from mother to baby from their shared blood supply during pregnancy or by contact with the mother’s blood during childbirth. One case of dengue virus infection in a baby linked to breastfeeding has been reported to date.

Can dengue virus infection be spread through blood?

Dengue virus infection can be transmitted through blood. People who have travelled to affected areas should not give blood (www.giveblood.ie).

How can I protect myself from being bitten by mosquitoes?

  • Avoid being bitten by mosquitos at all times of the day, as dengue is spread by a mosquito that bites during the day, particularly early in the morning and in the evening before sunset.
  • Avoid areas where mosquitoes live and breed, such as near standing or slow moving water including rain water collections, ponds, lakes and marshes. Find and remove possible mosquito breeding sites, such as standing collections of rain water.
  • Protect your skin from mosquito bites by wearing long sleeves, long trousers and hats
  • Use bug spray and read the instructions on the label carefully before use
    • A suitable bug spray (such as DEET) can be obtained from your local pharmacy
    • Bug spray can be used on clothing, shoes, tents, mosquito nets and other gear. Your local pharmacist can advise you on the most suitable product to use.
    • DEET is safe to use during pregnancy and while breastfeeding but only in concentrations less than 50%
    • DEET is only safe for babies aged 2 months and older
    • If using sunscreen, bug spray should be applied after sunscreen
  • When you sleep during the day or night, protect yourself with insecticide-treated mosquito bed or cot nets. If the net does not touch the floor, tuck the net under the mattress.
  • Indoors: Mosquito bites can be reduced by using air conditioning, insect-proof screens on windows and doors and spraying the room with bug spray

Further information on preventing mosquito bites is available from the HPSC website.

How is dengue virus infection treated?

There is no vaccine or specific drug for dengue virus infection. The patient is treated to relieve pain, fever and any other symptoms. To prevent dehydration, patients should control the fever with medicine and tepid sponge baths, rest and drink plenty of water.

How is dengue virus infection diagnosed?

Laboratory tests are available to check if your blood has made antibodies to fight dengue virus infection. The National Virus Reference Laboratory carries out a serology test and a positive test result is confirmed by the Rare and Imported Pathogens Laboratory in the UK. Your doctor may order other laboratory tests to rule out other conditions with similar symptoms.

Have cases of dengue virus infection been diagnosed in Ireland?

Cases of dengue virus infection in Ireland are diagnosed each year in a small number of travellers returning from affected areas. Latest data and reports on dengue virus infection reported in Ireland are available on www.hpsc.ie.

Are people in Ireland at risk of dengue virus infection

Dengue virus infection can be brought into Ireland in a traveller returning from an affected area. However, as the virus is not spread through person to person contact, the virus is unlikely to spread further. The mosquito that spreads dengue virus infection has not been found in Ireland to date.

What countries are affected by dengue virus infection?

Dengue is found in more than 100 countries in Africa, the Americas, South-East Asia, the Western Pacific and the eastern Mediterranean. Maps of the global situation can be found on the websites of the World Health Organization and the Centers for Disease Control, US while the European Centre for Disease Prevention and Control provides information on dengue virus infections reported in Europe.

What is the current travel advice?

The Department of Foreign Affairs and Trade (DFA) provides guidance to travellers that is updated regularly. Please consult the DFA website and click on the relevant country. It is important to check this information prior to any trips, as the situation could change rapidly.

What do I do if I’m living / working in an area where dengue virus infection is circulating?

The best way to avoid dengue virus infection is to protect yourself against mosquito bites. If you become ill you should contact your local health care provider who will be able to advise on your individual circumstances.

What do I do if I am travelling to an area where dengue virus infection is circulating?

  • All travellers going to an affected area should take measures to prevent becoming infected with dengue virus infection.
  • Irish citizens who live in affected areas should also take measures to prevent becoming infected with dengue virus infection.
  • People showing symptoms that could be dengue virus infection within 14 days after returning from an affected area should contact their healthcare provider.

Please see further travel advice on the HPSC website.

What do I do if I’m returning to Ireland from an area where dengue virus infection is circulating?

If you become ill when you return to Ireland, you should contact your doctor for assessment and let him/her know of your recent travel history to an affected area.

Last updated: 08/03/2019