By Dr Ritesh Kohli, MD
Dengue fever is an infectious disease carried by mosquitoes and caused by any of the four related dengue viruses. This disease used to be called the ‘break-bone’ fever because it causes severe joint and muscle pain. In earlier times, this disease was believed to be a curse of Satan (by the witch doctors of Africa).
Dengue fever is found mostly during and shortly after the rainy season in tropical and subtropical areas of Africa, Southeast Asia and China, India, Middle East, Caribbean and Central and South America, Australia and South and Central Pacific.
Cause
Dengue fever can be caused by any one of four types of dengue virus: DEN-1, DEN-2, DEN-3, and DEN-4. You may be infected by at least two, if not all four types at different times during your lifetime, but only once by the same type. DEN – 2 is relatively common in Guyana.
Transmission
You can get dengue infections from the bite of an infected Aedes mosquito which is a domestic, day-biting mosquito. Mosquitoes become infected when they bite infected humans, and then transmit this infection to other people they bite. The two main species of mosquitoes, Aedes aegypti and Aedes albopictus, are responsible for all cases of dengue transmitted in this country. The mosquito flourishes during the rainy season but may breed in water-filled flower pots, plastic bags and cans all year round. Dengue is not contagious from person to person.
Symptoms
Symptoms of typical uncomplicated (classic) dengue usually start with fever within 4 to 7 days after you have been bitten by an infected mosquito and include:
* High fever, up to 105ºF
* Severe headache
* Retro-orbital (behind the eye) pain
* Severe joint and muscle pain
* Nausea and vomiting
* Rash
The rash may appear over most of your body 3 to 4 days after the fever begins and then subside after 1 to 2 days. You may get a second rash a few days later.
Symptoms of dengue haemorrhagic fever include all of the symptoms of classic dengue plus
* Marked damage to blood and lymph
vessels
* Bleeding from the nose, gums, or
under the skin, causing purple
coloured bruises
This form of dengue disease can cause death.
Symptoms of dengue shock syndrome − the most severe form of dengue disease − include all of the symptoms of classic dengue and dengue haemorrhagic fever, plus
* Fluid leaking out of blood vessels
* Massive bleeding
* Shock (very low blood pressure)
It is sometimes fatal, if circulatory failure is not corrected immediately.
Diagnosis
Your doctor can diagnose dengue fever by doing blood tests to see whether a sample of your blood contains antibodies to the virus. An immune response with antibodies to the virus takes 5 to 7 days so in the first week of the onset of symptoms, serological tests may be negative.
Treatment
Because dengue is caused by a virus, there is no specific medication to treat it.
If you have a mild form of the disease, your doctor will recommend drinking enough fluids to avoid dehydration from vomiting and high fever. You can also take acetaminophen (Tylenol) for pain and fever. Avoid aspirin or other nonsteroidal anti-inflammatory drugs, such as Ibuprofen. These can increase the risk of bleeding complications.
If you have a more severe form of the disease, treatment consists of supportive care in a hospital. Such care includes intravenous fluids and electrolyte replacement, maintaining adequate blood pressure and replacing blood loss.
If you have any form of dengue fever, you should be kept away from mosquitoes, to avoid transmitting the disease to others.
Prevention
The best way to prevent dengue virus infection is to take special precautions to avoid being bitten by mosquitoes. Several dengue vaccines are being developed, but none is licensed by the Food and Drug Administration at present.
When outdoors in an area where dengue fever has been found
* Use a mosquito repellent containing
DEET, picaridin, or oil of lemon
eucalyptus
* Dress in protective clothing — long-
sleeved shirts, long pants, socks, and
shoes
Because Aedes mosquitoes usually bite during the day, be sure to take precautions, especially during the early morning hours before daybreak and in the late afternoon before dark.
Other precautions include:
* Keeping unscreened windows and doors
closed
* Keeping window and door screens in
good repair
* Eliminating areas where mosquitoes
breed, such as stagnant water in flower
pots, containers, discarded tyres, etc.
Prognosis
* Recovery from infection provides lifelong immunity against that particular virus but confers only partial and transient protection against subsequent infection by the other three viruses. Subsequent infection increases the risk of developing dengue haemorrhagic fever.
We can prevent the epidemic of dengue/DHF, by a co-ordinated community effort. Residents living in areas infested with Aedes aegypti should take the responsibility of eliminating the places where the mosquitoes breed, primarily artificial containers that hold water. Because the initial symptoms of dengue fever resemble ’flu like illness, all patients suffering from fever associated with headache and body pains should consult the doctor immediately, and even if initial blood investigations are normal, should come for a follow-up and repeat the blood test.
