Dengue

What is DENGUE?

Dengue is a human disease caused by a virus transmitted by mosquitoes. It occurs commonly in tropical and subtropical regions of the world, predominantly in urban-suburban areas. It is the most important arboviral disease of humans, affecting 50-100 million persons annually (Gubler 2000). The word dengue is a Spanish attempt at the Swahili phrase ki denga pepo which describes a cramp-like seizure.

The Vectors

The main vector of dengue is the yellow fever mosquito Aedes aegypti, but the Asian tiger mosquito, Aedes albopictus is also a competent vector and can function as an interhabitat bridge vector for the arboviruses. Ae. aegypti is a medium-sized dark mosquito with black and white striped legs and a silvery white lyre shaped pattern of scales on the dorsal side of the thorax .

Classic Signs of Dengue:

FEVER

• Sudden and abrupt onset
• May go up to 39.5-41.4°C
• Lasts for about 1-7 days, then fades away for 1-2 days
• It soon recurs with secondary rashes which is usually not as severe as before.

 HEADACHES

• Fever is usually accompanied by headache in front portion of head or behind the eyes.

Muscular (Myalgia) or bone pain

• Occurs after onset of fever
• Affects legs, joints, and lumbar spine 
• Usually the pain gets severe after its onset. 
• The pain may last for several weeks even after the fever has subsided.

Other Symptoms:

• Nausea and vomiting
• Loss of apetite
• Increased sensation to touch
• Change in taste sensation 

Symptoms maybe milder in children than in adults,  The acute phase of illness can last for 1 week followed by a 1 to 2 week period of recovery period that is characterized by weakness, malaise and loss of appetite.

How to Avoid Dengue Fever:

1. Water from flower pots should be changed at least once a week
2. All containers storing water should be covered with a tight lid
3. Water stored in barrels, drums etc should be replaced by fresh stock (at least) once a week
4. All large water tanks, like those in buildings, should have single piece cast iron, tight fitting cover. A suitable ladder should be provided to enable civic staff to climb and examine the tanks at frequent intervals. The overflow pipe should be protected by a net that can keep away mosquitoes.
5. Discarded container-like objects like tyres, coconut shells, bottles, etc should be disposed off or destroyed.
6. Water fountains should be kept dry once a week
7. Surface wells should be well-maintained so that mosquitoes do not breed in the vicinity
8. Rain water collected on terraces/roofs should be cleared (at least) once a week.

 Treatment of Dengue

There are no specific anti-viral tablets or injections that can kill the virus. However a lot of supportive care and treatment can go a long way to save a patient suffering from dengue fever.

Fever is treated by anti-pyretics, like paracetamol.

Pain in the bone should be treated by analgesics or pain killing tablets.

In case of Dengue Hemorrhagic Fever or Dengue Shock Syndrome hospitalization is a must. The mortality rate in the absence of hospitalization can be as high as 50%. With proper treatment the mortality comes down to 3%. More supportive treatment, like intravenous fluid replacement is required to prevent shock in these patients.

Vaccines are being developed against all 4 serotypes and they will definitely be the most effective way to prevent the disease.

Prevention of mosquito breeding has by and large failed in most endemic countries.
Patients are prone to dehydration hence they should drink plenty of fluids. If necessary a few days of intra-venous fluids can be administered in the form of normal saline or dextrose saline.

Dengue mosquitoes bite during daytime. Protect yourself from the bite.

R. Y. MANABAT, R.N.