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Magazine
Dealing with dengue
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Dr. B. RAMACHANDRAN explains how dengue fever spreads and the steps towards its prevention.
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Because the symptoms of dengue fever are non-specific and resemble those of many other diseases, it is difficult to diagnose it early.
What is dengue fever?
DENGUE FEVER (DF) is an acute illness caused by several viruses that are spread through the bite infected mosquitoes.
How does one get dengue fever?
DF is transmitted by the bite of certain mosquitoes called Aedes aegypti. These are different from those that transmit malaria and generally bite during the daytime. They breed easily in stored water, puddles, etc. The mosquito is infected when it bites a person with dengue fever and then transmits the virus to healthy people when bites them.
What are the symptoms of DF?
DF can affect both children and adults. A sudden onset of high fever, headache, a transient body rash, a sore throat and cough are the first signs. There may be severe body ache, loss of appetite, nausea and vomiting. These resemble many other illnesses, including flu. After four to six days, the fever subsides and a generalised rash may appear. Sometimes, the disease is more severe and the patient develops lethargy, cold extremities, poor pulses and low blood pressure. This is called Dengue Hemorrhagic Fever or Dengue Shock Syndrome. These patients may also develop bleeding tendencies due to abnormalities of blood clotting and low platelet counts.
How is it diagnosed?
Because its symptoms are nonspecific and resemble those of many other diseases, it is difficult to diagnose it early. Certain blood tests are available but they may be negative initially but show as positive when repeated after several days.
How is DF treated?
There is no specific treatment against the virus but supportive measures are extremely important. Mild infections can be treated at home with simple measures like bed rest, taking fluids and Paracetamol for fever. Most patients will recover spontaneously and your doctor will inform you about symptoms to watch out for, including restlessness, lethargy, and cold extremities, which indicate deterioration. Patients who are more severely infected must be admitted to a hospital. Usually, supportive measures like intravenous fluids will suffice. Antibiotics will not act on the Dengue virus but may be administered if a secondary bacterial infection is suspected. Severely ill patients must be treated in an intensive care unit. Large amounts of blood products, such as fresh frozen plasma, packed red cells and platelets may be required. Some patients may require mechanical ventilation. Most patients will recover but serious complications or even death can occur in a minority.
Can a person who has had dengue catch it again?
There are four different types of the dengue virus and infection by one provides immunity only against that type. Therefore, it is still possible to develop DF if infected by another type of the virus.
How can DF be prevented?
Since there is no specific cure, prevention is extremely important.
Public health measures to minimise mosquito breeding are important. These include spraying entire areas with an insecticide fog to kill adult mosquitoes, it is important to open all the windows and doors while that operation is on so that the insecticide can also act on mosquitoes inside houses.
The adult mosquitoes have a limited flight range and usually bite in the area where they breed. They require clean water and breed in collections of water in and around houses including stored water, rainwater, discarded containers or tyres, and even the water inside flower vases. All water should be kept in containers with tight fitting lids. Sumps and overhead tanks should also have mosquito proof lids. Remove any containers in your neighbourhood that can collect rainwater.
At a personal level, take steps to prevent mosquito bites, such as using long trousers and shirts. Mosquito nets may not be of much use since these mosquitoes bite in the daytime. Mosquito repellent creams are effective when used properly.
A recent study has determined that preparations containing diethyl toluamide, also known as diethyl-3-methlbenzamide (DEET) provide maximum protection. Creams should be applied to all exposed areas of the body and should be reapplied every four to five hours. Anti-mosquito mats and vapourisers provide effective indoor protection. Though mosquito coils may be effective, the long-term effects of exposure to the smoke are unknown.
Is DF contagious?
Dengue cannot spread from one person to another directly.
How can I help?
In addition to the mosquito control measures detailed above, blood donation also helps. Each year during the dengue season, there is a tremendous shortage of blood and blood products. All healthy adults can donate blood once every three months, without any side-effects.
Make it a point to donate regularly and encourage your friends and relatives to do so.
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