Dengue Update and prevention

Dr. Amitabh Khanna

1. Dengue is a notifiable illness.
2. There are four different types of dengue fever 1, 2, 3, and 4.
3. A person can suffer from undifferentiated fever, dengue fever, dengue hemorrhagic fever, dengue shock syndrome (four dengue related illnesses).
4. Retro orbital pain presenting as pain in the eyes or pressure on eye movement is characteristic of dengue related fever.
5. A person in his life time can get four attacks of dengue fever or related illnesses.
6. Presence of restlessness (oxygen deficiency in the brain), abdominal pain (indicating internal hemorrhage) and black stools (GI bleeding) signifies urgency.
7. The two dangerous clinical signs are falling systolic blood pressure and fall in pulse pressure.
8. The mortality for dengue hemorrhagic fever and dengue shock syndrome is around 1%.
9. There is no mortality seen in undifferentiated fever and dengue fever.
10. During epidemics, people of all ages are involved otherwise the disease is more common in children.
11. If dengue is reported in one house it becomes customary for the State Health Department to search for the breeding sites around 100 houses so that the disease can be curtailed there and then.
12. Dengue and malaria are not the indices of the hygiene status of a city. Cholera and typhoid represent the hygiene indices.
13. Dengue mosquito, aedes, grows in fresh water collected in any place within or outside the house.
14. It is a day biter, prefers to bite before breakfast and after lunch, prefers human sites below elbow and below knee.
15. Unlike anopheles (mosquito causing malaria) which bites every 3rd day, a dengue mosquito bites 4-5 times a day.
16. While anopheles infects one person in 3 days, aedes mosquito can infect 15 persons in 3 days.
17. Infections from one cause life long immunity only for that strain.
18. IgM blood test may take 5 days to become positive. Therefore in the first 5 days all dengue tests may be negative.
19. A platelet count of less than one lakh signifies dengue hemorrhagic fever or dengue shock syndrome.
20. Do not give aspirin in the suspected case of dengue as it can further disturb the platelet functions.
21. Never panic. There is no need for platelet transfusion unless platelet count is less than 10,000 with active bleeding.

Prevention of Mosquito Breeding

The only way to prevent catching dengue fever at present is to protect yourself from getting mosquito bites. Scientists are trying to develop vaccines against the four different types of the virus, but these are not yet available.

General advice for avoiding mosquito bites normally includes sleeping under a mosquito net and wearing loose-fitting long trousers and long-sleeved tops in the evening. However, these measures aren’t very effective against dengue, as the Aedes mosquito that transmits the infection normally bites during the day.

The following measures should also be taken to avoid getting bitten by mosquitoes during the day.
-Wear light-coloured, protective clothing, covering as much of the body as possible.
-Use an insect repellent on exposed skin and clothing, especially around dawn and dusk when the Aedes mosquito is most active. Repellents containing a chemical known as DEET (N, N-diethylmetatoluamide) are thought to be most effective.
-Use insecticide sprays to kill mosquitoes.
-Avoid areas where the mosquitoes breed (normally in standing water in domestic containers, around urban areas). You can also remove such sources of water or cover them to prevent access by mosquitoes.
-Avoid stagnant water around houses to get rid of mosquito breeding sites. Clear water from:
Flower pots , Buckets, Barrels, Tyres
-Store water under cover
-Use bleaching powder mixed in water if it is not tube used for drinking.