Dengue Fever

Dengue Fever

Dengue fever is a viral illness caused by infection with 1 of 4 types of the dengue virus. When a person recovers from dengue infection they develop a long-term (not always lifetime) immunity to that type, but not the other 3 types. If the person is infected again with a different virus type, they may develop the more severe form of the illness known as dengue haemorrhagic fever (DHF).

It is spread by the bite of an infected dengue mosquito (usually the Aedes aegypti species). There is no spread from human to human. Only the female mosquito transmits the virus. They are most active during daylight hours. They rest indoors in closets, behind curtains and other dark places. Outdoors they rest where it is cool and shaded.

It usually takes 3 to 14 days (commonly 4-7 days) between getting bitten by a dengue virus infected mosquito and becoming sick.
Dengue fever
Dengue fever is more commonly seen in older children and adults. It is characterised by abrupt onset of high fever lasting 3-7 days, severe frontal headache, pain behind the eyes and muscle and joint pains. Other symptoms may include loss of appetite, nausea, vomiting and diarrhoea, a blanching rash and sometimes minor bleeding (eg from nose and gums).The acute symptoms of dengue fever last up to 10 days. Some people may experience repeated episodes of fever.
Full recovery may be slow and associated with weakness and depression. It is rarely fatal.

Dengue haemorrhagic fever( DHF)
DHF is most commonly seen in children under 15 years of age but can also occur in adults. It begins with the same symptoms as dengue fever but is followed by rapid deterioration, bleeding and cardiovascular collapse 2-5 days later.

The duration of DHF depends on the severity of the illness and response to treatment. It can be fatal.
What is the treatment?
There is no specific treatment or vaccine. Supportive treatment includes plenty of oral fluids and paracetamol for relief of fever and body aches and pains. Aspirin and non-steroidal anti-inflammatory drugs should not be used as they can affect blood clotting. Anyone with DHF should be hospitalised for fluid replacement and observation.

Personal Protective Measures
1. Avoid areas of likely mosquito activity

2. Wear loose light coloured clothing with long sleeves, trousers and socks

Use repellents containing di-ethyl-toluamide (DEET) or picaridin as supplements to protective clothing

3. Ensure flyscreens in houses, caravans and tents are in good repair

4. Use mosquito coils and electric insecticide vapour mats or mosquito lanterns in enclosed or sheltered areas.

5. Empty and apply surface spray to any old unused container that has held water eg tyres, plastic containers, black sheet plastic or pot plant drip trays. Store any containers upside down and undercover or under a domed tarpaulin in good repair.

6. Avoid using saucers or drip trays under pot plants. Let pots drain directly onto the ground or make sure saucers are emptied at least once/week. Wipe their inner surface firmly with a cloth several times or fill with sand, or apply surface spray or methoprene insecticide pellets.

7. Empty bird baths and pet drinking water at least weekly and wipe as above, or use methoprene pellets.

8. Cover and completely seal septic tanks, rainwater tanks or other large water storage containers. Use methoprene briquettes in unsealed tanks as a temporary measure.

9. Dispose of rubbish around the yard that may collect water eg; plastic sheets or old tarpaulins, pot plant holders, old wheelbarrows, old tyres, and plastic containers of any type.

10. Ensure roof gutters drain freely so that pools of water are not left at any low points. Throw a small amount of methoprene pellets on to the roof above problem gutters.

11. Fishponds with fish do not breed mosquitoes. Tadpoles do not eat mosquito larvae. Keep fishponds and frog ponds stocked with fish and do not spray surface spray onto or at the edge of fishponds.