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Dispelling the hazards
By Hiranthi Fernando
Swarms of mosquitoes had invaded our neighbourhood. With the threat of dengue looming over the city, residents were concerned that empty tins and bottles, collecting water in a non-residential premises nearby, were a health hazard. A complaint was made to the Pest Control Unit of the Colombo Municipal Council (CMC).

It was indeed a surprise to find quick action taken by the PCU the very next day. A team was sent by the Pest Control Unit to spray and fog the area. The offending party was warned that court action would be taken if the premises were not cleaned up. There was an immediate respite from the mosquito menace and the people were relieved. A follow-up was made two weeks later.

The PCU comes under the Public Health Department of the CMC. The main function of this Central Unit is to distribute the materials and machinery to the six MOH divisions in the city for the control of mosquitoes and other pests. They also handle what the MOH divisions cannot undertake.

"There are usually pockets of breeding places of mosquitoes," said Acting Pest Control Officer of the Central Unit W. Edirisuriya. "When we get information on Dengue cases, we send a team to the area. To cover the breeding pocket, the Ultra Level Volume (ULV) machines are taken round the area so that we spray the whole pocket. After that we fog the area. The Chief Medical Officer gives instructions for special programmes that need to be carried out from time to time," Mr. Edirisuriya explained.

Canals in the city are power sprayed by boat. Four labourers are needed for this task, which is undertaken once in two weeks. At the canal on Kirimandala Road, a boat team was preparing to embark on the canal spraying programme. The water is examined for larvae using a long handled spoon.

Mr. K. Weerakoon, who had worked as a university PHI for forty years was also at the site. "WHO has given us Sumilarva," Mr. Weerakoon said. "It is an enzyme which retards the growth of the mosquito larva. The enzyme only affects the mosquito larvae and fish do not die."

According to Mr. Edirisuriya, in many malaria-prone areas, they use a larvicide, which is not dangerous for the people and animals who use the waterways for bathing and drinking. The motor used in the canal spraying can spray a distance of about 100 feet. They spray from Kirimandala to Wellawatte on one day. The next time the boat goes on the canal which branches off to Dehiwela. In the other direction they go up to Rajagiriya. The boat can only be taken along the main canals.

Cleaning of the smaller branch canals are undertaken by the MOH divisions. Mr. Edirisuriya says it is very difficult to navigate a boat along these canals. The engine gets entangled in the polythene and other garbage in the canal. The boat also gets stuck in the mud. The PCU has recently got a new boat for the canal spraying.

Apart from mosquito control, the PCU also undertakes rat and cockroach control. When they receive complaints from residents, they inspect the premises and send people for spraying, Mr. Edirisuriya said. Racumin is given for control of rats.

However, some people do not favour using this as it is a poison. In such instances, the PCU gives cages for catching rats. The rats are then handed over to the Medical Faculty for research purposes.

The Chief Medical Officer of the CMC, Dr. Pradeep Kariyawasam said public cooperation is essential for the effective control of Dengue. The Green Star Homes campaign is one of the programmes for controlling mosquito breeding in residences. Homes are inspected and based on a set of criteria, a sticker is issued to the homes that are free of mosquito breeding places.

"We select high risk areas from our maps and have one-day campaigns in these areas," Dr. Kariyawasam said. "We use about 1000 volunteers including medical students, scouts, Rotarians and our own staff. They go from house to house in the selected areas distributing leaflets and issuing stickers." Last year the campaign was carried out before the rainy season so there were no major outbreaks of Dengue. This year's programme, which was fixed for April 2 had to be postponed due to the elections. A media campaign has also been planned for this year.

Dr. Kariyawasam said they now collect data on Dengue admissions from all the hospitals in the city and find out from where the cases originate. A 60% reduction of admissions to government hospitals has been noted.

"Mosquitoes go for high density areas. We have found that where there are security forces’ barracks or highly populated flats, there are a large number of Dengue cases. The reason is that there are common areas for which no one takes responsibility. Also people from the top floors throw empty tins, yoghurt cups and so on down from the windows. We are trying to activate management cooperation."

When a mosquito breeding area has been detected, the UVL machines are sent to spray. Health education and regular clean-ups are the only way to get rid of Dengue Dr. Kariyawasam stresses.

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