Q.12 Write a note on Dengue Fever.
Answer:
Introduction
It is a viral infection transmitted through a mosquito Aedes aegypti. Occurrence
It has become a major health problem in tropical and sub-tropical countries, including Pakistan. Types of Dengue Virus
There are four types of dengue viruses. Recovery from infection by one provides lifelong immunity against that virus but provides no protection against infection by the other three.
Dengue Infection per year
According to WHO, there are 50 million dengue infections worldwide every year. Now there are 2.5 billion people at risk from dengue.
Spreading
The female Aedes mosquito gets the virus when it bites an infected person. When an infected mosquito bites another person, viruses enter his/her blood and attack white blood cells. Inside WBCs, viruses reproduce and destroy them.
In severe cases, the virus affects liver and bone marrow. As a result there is a decrease in the production of blood platelets and patient suffers from bleeding.
Other symptoms
High fever, severe headache, pain behind eyes, muscle joint pains and rash
DHF and DSS
Sometimes, dengue fever converts into dengue haemorrhagic fever (DHF) or into dengue shock syndrome (DSS). DHF results in bleeding, low levels of blood platelets and blood plasma leakage. In DSS, the blood pressure falls dangerously low.
Treatment
There is no vaccine or treatment for dengue fever.
Control
(a) Check the spreading of Aedes
At present, the only method of controlling dengue virus transmission is to check the spread of Aedes mosquitoes. Aedes aegypti breeds primarily in the containers used for water storage, discarded plastic containers, used automobile tyres and other items that collect rainwater.
(b) Proper solid waste disposal
The mosquitoes can be controlled through proper solid waste disposal and improved water storage practices.
(c) Killing the Larvae of the Mosquito
Small fish and crustaceans have also been used for killing the larvae of the mosquito. Insecticide sprays have not proved efficient in killing the mosquitoes because spray does not penetrate all habitats of adult mosquitoes.
