What is Dengue fever (DF)?

Dengue infection is caused by a virus. It occurs commonly as dengue fever. Occasionally the patient suffering from dengue may develop bleeding. Common sites for bleeding are nose, gums or skin. Sometimes, the patient may have  coffee ground vomiting or black stools. This indicates bleeding in gastro intestinal tracts and it is serious. The patient with dengue who has bleeding has dengue haemorrhagic fever (DHF ). Rarely the patient suffering from dengue may develop shock, then it is called dengue shock syndrome ( DSS).

Dengue should be suspected when you have sudden onset of fever. The fever is high 103-105 degrees F or 39-40 degrees C. It is accompanied with severe headache (mostly in the forehead), pain behind the eyes, body aches and pains, rash on the skin and nausea or vomiting. The fever lasts for 5-7 days. In some patients, fever comes down on 3^rd or 4^th day but comes back. All the above symptoms and signs may not be present in the patient. The patient feels much discomfort after the illness.

The characteristics of dengue that make it different from other causes of fever are the pain behind the eyes, severe pains in the muscles, severe joint pains, and skin rashes. These features make the diagnosis of suspected Dengue likely. The severe joint pains caused by DF is the reason why DF is also called break-bone fever.

If a patient suspected to be having dengue has reduced platelets or an increase in blood haematocrit, then the patient has probable dengue. These additional findings makes dengue more likely. Patients with dengue may not have a high haematocrit if the person was anaemic to start with.

(Platelets are cells in blood that help to stop bleeding. Haematocrit indicates the thickness of blood).

It is possible to get dengue more than once. Dengue can occur because of 4 different but related strains of dengue virus. If a person has suffered from one virus, there can be a repeat occurrence of dengue if a different strain is involved subsequently. Being affected by one strain offers no protection against the others. A person could suffer from dengue more than once in her/his lifetime.

There are laboratory tests that provide direct or indirect evidence for dengue fever. These tests provide evidence for the occurrence of dengue infection. There are some additional tests that can help to identify the type of dengue infection. The tests for confirmation of Dengue should be done in reliable laboratories.

Dengue fever occurs following the bite of an infected mosquito Aedes aegypti.This type of mosquito has a peculiar white spotted body and legs and is easy to recognize even by laymen. It breeds in clean water (see Question 20) and has a flight range of only 100 – 200 metres.The mosquito gets the Dengue virus after biting a human being infected with dengue virus.

Dengue does not spread directly from person to person. It is only spread through the bite of an infected mosquito.

After the entry of the virus in the person, it multiplies in the lymph glands in the body. The symptoms develop when the virus has multiplied in sufficient numbers to cause the symptoms. This happens generally about 4-6 days ( average) after getting infected with the virus.

Yes. There are many people who are infected with the virus and do not suffer from any signs or symptoms of the disease. For every patient with symptoms and signs there may be 4-5 persons with no symptoms or with very mild symptoms.

Most patients with dengue fever can be treated at home. They should take rest, drink plenty of fluids that are available at home and eat nutritious diet. Whenever available, Oral Rehydration Salt/ORS (commonly used in treating diarrhoea) is preferable. Sufficient fluid intake is very important and becomes more important in case DF progresses into DHF or DSS where loss of body fluid / blood is the most salient feature.It is important to look  for danger signs and contact the doctor as soon as any one or more of these are found.

Like most viral diseases there is no specific cure for dengue fever. Antibiotics do not help. Paracetamol (can be purchased without prescription) is the drug of choice to bring down fever and joint pain. Other medicines such as Aspirin and Brufenshould be avoided since they can increase the risk of bleeding. Doctors should be very careful when prescribing medicines. Any medicines that decrease platelets should be avoided.

The infection can become dangerous since it may cause damage to the blood vessels. The damage may range from increased permeability of the blood vessels, causing leakage of blood fluid/plasma into various organs to completely broken blood vessels that causes bleeding.The symptoms and signs of dengue haemorrhagic fever and dengue shock syndrome are related to damage to the blood vessels and derangement in functioning in components of blood that help it to clot.

People who suffer from dengue fever have no risk of death but some of them develop Dengue Haemorrhagic Fever or Dengue Shock Syndrome. In some of these cases death can occur. With proper treatment, the patients with Dengue haemorrhagic fever and dengue shock syndrome can recover fully. Good treatment provided in time can save most lives.

Generally the progress towardsdengue haemorrhagic fever or dengue shock syndrome occur after 3-5 days of fever. At this time, fever has often come down. This may mislead many of us to believe that the patient is heading towards recovery. In fact, this is the most dangerous period that requires high vigilance from care-givers. The signs and symptoms that should be looked for are severe pain in the abdomen, persistent vomiting, bleeding from any site like, bleeding in the skin appearing as small red or purplish spots, nose bleed, bleeding from gums, passage of black stools like coal tar. Bring the patient to the hospital whenever the first two signs, namely, severe pain in the abdomen and persistent vomiting are detected. Usually it is too late if we wait until bleeding has occurred.

The most dangerous type of dengue is the dengue shock syndrome. It is recognized by signs like excessive thirst, pale and cold skin (due to very low blood pressure), restlessness and a feeling of weakness.

A vaccine has been developed to prevent dengue fever but it is still under trial. It is not yet available in the market. Scientific progress is likely to help in prevention of dengue fever by vaccination in the years to come.

Most people who suffer from dengue fever recover in 1-2 weeks time. Some may feel tired for several weeks. However, if symptoms persist after this period, consult a doctor.

The highly domestic mosquito Aedes aegypti rests indoors, in closets and other dark places. Outside it rests where it is cool and shaded. The female mosquito lays her eggs in water containers in and around the homes, and other dwellings. These eggs will develop, become larvae, and further develop into adults in about 10 days.

Dengue mosquitoes breed in stored, exposed water collections. Favoured places for breeding are barrels, drums, jars, pots, buckets, flower vases, plant saucers, tanks, discarded bottles, tins, tyres, water coolers etc.

To prevent the mosquitoes from multiplying, drain out the water from desert coolers/window air coolers (when not in use), tanks, barrels, drums, buckets etc. Remove all objects containing water (e.g. plant saucers etc.) from the house. Collect and destroy discarded containers in which water collects e.g. bottles, plastic bags, tins, used tyres etc.

In case it is not possible to drain out various water collections or to fully cover them, use TEMEPHOS, an insecticide, ( brand name Abate) 1 part per million according to the local guidelines to prevent larvae from developing into adults.

There is no way to tell if a mosquito is carrying the dengue virus. Therefore, people must protect themselves from all mosquito bites.

Dengue mosquitoes bite during the day time throughout the day. Highest biting intensity is about 2 hours after sunrise and before sunset.

Wear full sleeves clothes and long dresses to cover as much of your body as possible.

Use repellents- be careful in using them in young children and old people.

Use mosquito coils and electric vapour mats during the daytime also to prevent dengue.

Use mosquito nets to protect children, old people and others who may rest during the day. The effectiveness of these nets can be improved by treating them with permethrin (pyrethroid insecticide). This bed-net is called Insecticide Treated Nets and are widely used in the prevention of malaria.