Public awareness a must to avoid dengue fever outbreak

Important risk factors for seasonal appearance of the infection in existence

Islamabad

The confirmation of well over 40 patients of dengue fever in last three months in this region of the country along with existence of important risk factors for seasonal appearance of the infection convinced health experts to stress on creating awareness among public on how to avoid a possible outbreak of the infection that may hit population in next few days.

The most important thing at the time is to make public aware of the risk factors and preventive measures to be taken to avoid outbreak. The health departments in the country should start social mobilisation campaigns and contact individuals to take matter seriously to ensure destroying of possible breeding sites of mosquitoes and adult mosquitoes inside and around their houses.

At the time, awareness among public can play the greatest role in avoiding a possible outbreak of dengue fever.

Assistant District Health Officer at ICT Health Department and Member Global Outbreak Alert and Response Network (GOARN) Dr Muhammad Najeeb Durrani expressed this while talking to 'The News' on Monday.

He said the dengue mosquitoes both Aedes Aegypti and Aedes Albopictus are vectors for causing dengue fever as the female mosquitoes carry one of the four types of Dengue Virus from the dengue patient to the healthy person and transmit the disease.

The population of aedes aegypti fluctuates with temperature, rainfall and humidity. Dengue infections are generally encountered during or after rain, as an outcome of rise in vector population, he explained.

He said the optimal temperature for aedes aegypti larvae is 28 degree centigrade. Above this, the rate of development is high and below 18 degree centigrade, the growth gets prolonged. Above 36 degree centigrade, the larval development is not complete. Extreme hot and dry weather may kill most of the eggs and render adult vectors inactive, he said.

He said the aedes aegypti population is high in rainy season and low in extreme hot weather. During rainy season, the risk of virus transmission by the vector is greater. Control measures of aedes aegypti larvae is necessary as Dengue Fever (DF) and Dengue Haemorrhagic Fever (DHF) cases increase proportionally with the larval density, he said.

He said it is important to organise dengue control programmes to reduce the mosquito-genic sites and to control the immature and adult aedes aegypti. "The maximum aedes aegypti larval density is noticed during July to October and in rainy season reaching its peak in September."

Dr. Durrani said after emergence and insemination, adult females seek human host to take a blood meal, rest in a sheltered place for a few days needed for the eggs to mature and then search for the sites to lay eggs where the mosquito can complete its cycle and breed. The mosquitoes need artificial container of any type (metal, glass, stone, plastic, rubber etc even empty hole of tablet's blister), or small natural water bodies like tree holes.

He explained that eggs they hatch can last from few days to several months in desiccation period as the eggs remain in dormant period till the availability of a conducive environment when these are submerged in water by the rainfall or the artificial man made flooding, eggs hatch and the larvae mature through four stages before entering pupation.

He added that the effects of temperature, rainfall and artificial flooding (man-made watering of lawns, fields and water spillage) are the genuine factors besides movement of infected patients from areas where there has recently been an outbreak of Dengue Fever to cause the disease.

As an epidemiological finding we always expect a surge in dengue fever cases after the rains when an outbreak is already occurring in adjoining areas, districts or other parts of the country, he said while responding to a query.

He added that the incidence of dengue fever and its outbreak can be avoided by avoiding breeding of mosquitoes and by controlling their growth and it is time to take precautionary measures religiously by both the concerned government authorities and the individuals.