Publication: Sunday Sun / Special Sections
Paper Section And Page: 8
Paper Date: Sun, Mar 5, 2000
Byline: Maurice Gaskin
THERE ARE three types of mosquitoes in Barbados with the capability of spreading more than six diseases and they work like a biological tag-team.
There is the culex mosquito which comes out in the late evening seeking blood meals between 6:30 p.m. to 7 a.m. Then there is the anopheles mosquito, found only in the Graeme Hall swamp, which goes to work immediately before and after the Culex, between 5 and 7 p.m., and again from 10 p.m. to midnight. These two are mainly night mosquitoes. But as the sun rises, the aedes aegypti mosquito, which lives around the home, awakens with the humans and seeks a breakfast blood feast from 7 to 10 a.m. It takes a siesta and returns for supper from 4 to 6 p.m. that is why fogging takes place at this time in the evening.
The Culex is capable of transmitting elephantiasis which causes swelling of the testicles, feet, hands, and neck. It can also transmit various diseases which cause inflammation of the brain such as St. Louis encephalitis, Japanese encephalitis and equine encephalitis.
The larvae of the Culex lie at a 45 degree angle to the surface of the water. The anopheles mosquito breeds in brackish water and this is why it is only found in the Graeme Hall swamp. Brackish water is a mixture of salty and fresh water. The anopheles spread malaria and its larvae can be easily recognised in water because they lie at a 180 degree angle (parallel to the surface).
The Aedes aegypti mosquito lives in and around homes and is presently the most dangerous mosquito in Barbados because the four strains of the dengue fever virus which it transmits are in circulation here. It can also spread yellow fever. The Aedes aegypti mosquito can lay its eggs in dry or wet containers. Those eggs will stay there for up to five years waiting for water. Once they get submerged in water they hatch within 48 hours. The larvae lie at a 90 degree angle in the water.
In order to spread the various diseases, the mosquito must take in contaminated blood. The virus in the blood then replicates itself. Afterwards, when the mosquito bites more people, the virus is transferred to the individual. Some of the diseases can be treated with vaccines or prevented using prophylactics, but there are no medicines which can treat dengue fever.
There are four strains of the dengue virus. When one becomes infected with a strain of dengue fever, one becomes immune to that particular strain. However, infection with more than one strain tends to weaken one's immune system and increases the risk of contracting dengue haemorrhagic fever (DHF) which may lead to dengue shock syndrome (DSS).
The symptoms of classical dengue fever are high fever, frontal headache, retro-orbital pain of the eyes, headaches, joint pains, rash, fatigue, sweating, conjunctivitis and red or purple blotches on the palate and skin as a result of bleeding.
Should these symptoms arise, one should go to the doctor and consume lots of liquids during the illness as well as paracetamol for the pain and fever. For children use liquid medicine such as Calpol, Paracetamol, or Aramol. NEVER use aspirin.
Symptoms of DHF includes restlessness, a sluggishness, bleeding any part of the body, and heavier than normal menstruation. By the time DHF starts, the high fever from the dengue fever would have started to subside giving the patient a false sense of recovery.
As there is no vaccine for dengue fever, the best way of controlling the disease is by preventing it. This can be done through the following methods:
- Maurice Gaskin is the Area Co-ordinator for Vector Control at the Warrens Polyclinic