MOSQUITOES have now become a threat to the comfort and lives of the people. They are in abundance everywhere in the country, especially after heavy rains. All mosquitoes breed in standing water, so eradication and its population control efforts usually involve removal and treatment of standing water sources.

A regular course of an effective insecticide spraying to kill mosquitoes should be undertaken across the country.

It has become extremely impossible to have a peaceful and sound sleep because mosquitoes’ itchy and irritating biting is troubling us from sunset till dawn.

Beyond the nuisance factor, mosquitoes are carriers or vectors for some of humanity’s most deadly illnesses like malaria, yellow fever and dengue.

A large number of people falling prey to dengue have lost their precious lives in the country. It is the prime duty of a city government to ensure regular cleanliness that include routine garbage collection and proper flow of sewerage water and effluent within its boundaries.

It is unfortunate that there have been advertisements in leading newspapers, claiming spraying city areas with insecticides, though in reality no one has yet witnessed any spraying anywhere in the city. And hence there is no decrease in mosquitoes’ armies. It is time the government did its job.

ANWAR HUSSAIN Karachi

Morbidity of the disease THIS is apropos of your editorials (Sept 14 and 17), as well as of reports by Mukhtar Alam earlier on, also his report in 2006 and your editorials (Oct 9 and 13 of 2006) which enabled the public, as well as many medical practitioners, to take greater cognizance of the morbidity of the disease. Community sensitisation is an important step for control of any disease or affliction amongst people. Without active community participation no programme of public health is ever going to succeed.

While spraying of insecticides can help to some extent, its effects cannot last for long. Repeated spraying may not be economically feasible if you work out cost of chemicals and the areas to be covered. Elimination of breeding places and personal protective measures are far more important. It is easier to detect and eliminate breeding places in many situations. Your earlier report about the breeding place of aedes in a house at GOR Colony at Lahore is pertinent.

When I was a medical college student in 1958, my book on public health and hygiene mentioned about the flight range of mosquitoes as five miles, depending upon the direction of the wind. In April 1970 I travelled from New York to London in one of the early 747 flights. In the plane I found a female culex mosquito which is responsible for transmission of a parasitic and some viral diseases. While aedes aegypti has been present for a long time in Pakistan I have noticed aedes albopictus only during the last five to six years. This species of aedes mosquitoes has been responsible for transmission of dengue fevers in Polynesia and some South Asian countries.

Mosquitoes can travel far greater distances than earlier thought. Whether aedes albopictus responsible for greater morbidity and mortality of the disease in the epidemics which occurred in India during 1996, 2006 and also greater incidence during the last few years at Karachi and Lahore. Perhaps, some one can write in your columns.

Migration of aedes albopictus from India to Pakistan cannot be denied. Mosquitoes can certainly avail the transport facilities by aeroplanes, trains, through buses and goods trucks. Another point to be noted is that once aedes mosquito becomes infected, it remains so far the rest of its life. This virus of dengue fever which the mosquito carries can be passed to the next generation. This phenomenon is known as transovarian generation, and can continue for four to five generations.

As for the treatment, let us be clear that there is no specific treatment like the one we have for malaria. As a part of supportive treatment platelets have been beneficial in serious cases. When not readily available, whole blood transfusion can help.

We are late by about five years to respond to the challenge of dengue. When an epidemic occurred in India, we should have thought that the insects do not need visas to travel from one country to another.

At present, despite the panic created in Lahore, it should be realised that dengue does not spread like influenza and the virus is not as virulent as the plague bascillus.

With greater participation of public in adopting preventive measures, it should be possible to control the disease.

PROF. KHALID HASSAN MAHMOOD Karachi