Fall in temperature does not support hatching, growth

 DENGUE FEVER VECTOR

Solid waste management, indoor surveillance keys to avoid outbreak in future

Rawalpindi

The sharp fall in temperature in the region at present does not allow mosquitoes to lay eggs and to hatch them, including ‘aedes aegypti’ and ‘aedes albopictus’, the vectors that cause dengue fever. The fall in temperature particularly below 13 degree centigrade also affects the biting ability and physiological functions of dengue fever vectors.

The recent dengue fever outbreak, much severe in nature, in the twin cities of Islamabad and Rawalpindi has already come to its seasonal end mainly because of the phenomenon. However, health experts believe that if we want to avoid dengue fever outbreak in future, it is a must to clear warmer places inside homes from larvae and possible breeding sites of mosquitoes along with working religiously for proper solid waste management during off season for the disease in the region.

The hatching of the eggs laid down by mosquitoes including ‘aedes aegypti’ could not be checked after four months or so, after rise in mercury, however if we want to avoid another dengue fever outbreak next year, we must take special measures for not giving eggs favourable conditions to survive.

Of course, the re-appearance of dengue fever outbreak with more chances of hemorrhagic manifestations expected in the months from July to November in 2017 can be checked by removing garbage dumps and unnecessary water accumulations on regular basis during the off season, said Additional District Health Officer at ICT Health Department Dr. Muhammad Najeeb Durrani while talking to ‘The News’.

Dr. Durrani, who is an epidemiologist has repeatedly expressed to ‘The News’ that the solid waste management is considered as the key to avoid dengue fever outbreak because the mosquitoes’ eggs do not need a huge quantity of water for keeping them alive and even a little moist that can be witnessed beneath the heaps of garbage is sufficient to keep them hatch-able for months.

It is important that only mature female ‘aedes aegypti’ mosquitoes infected with dengue virus transmit the disease and the whole life cycle of the species does not long for over 28 days and if temperature falls to a certain degree, below 13 to 14 degree centigrade, there would not be adult mosquitoes after four weeks.

The eggs of the mosquitoes, however, remain hatch-able for months in favourable conditions, in moist, said Dr. Durrani.

It is worth mentioning here that in the twin cities of Islamabad and Rawalpindi, a total of over 3,500 patients were tested positive for dengue fever during the recent outbreak of the infection that claimed at least eight lives at the three allied hospitals in Rawalpindi and three lives in hospitals in the federal capital this year.

When asked, Dr. Durrani said the most important thing at the time is to clear possible breeding sites inside homes as temperature inside homes does not fall below 13 degree centigrade normally. The fall in temperature slows down larvae production of ‘aedes aegypti’ from egg however, the mosquito may resist the fall in temperature from five to zero degree centigrade, he said.

The mosquitoes’ activity is decreased in outdoor environment in low temperature and they are not able to bite because of less energy in joints and they become unable to make a firm stand on the body of a person before sucking blood, he said.

It is important that the containers placed by the concerned government authorities in the twin cities of Islamabad and Rawalpindi may also serve as ideal places for mosquitoes for laying down eggs as under these containers and on their surfaces, there remains moist round the year.

After breeding of larvae of ‘aedes aegypti’, spread of dengue fever cannot be checked easily and hence, the off season is the most suitable time to work for checking hatching of mosquitoes’ eggs and breeding of larvae inside homes and in outdoor environment, said Dr. Durrani.