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Monsoonal rains may signal an increase in dengue patients


7 June 2017 12:00 am - 0     - {{hitsCtrl.values.hits}}


The record number of dengue patients and deaths recorded up to May this year mayincrease with the onset of the monsoonal rains. According to a Daily Mirror report last month, Dr. Prachila Samaraweera of the Dengue Control Unit of Colombo, has said some 44,000 dengue patients had been reported countrywide with 115 deaths. The number is massive compared to the previous year’s figure where some 55,000 dengue patients were reported with 97 deaths for the entire 2016. The increase in dengue patients is scary when considering that in 2015 there were only 30,000 dengue patients with 54 deaths.


While round table discussions are continuing and major campaigns including a three months dengue control programme has been launched, some important insights and simple and practical methods to control the spread of the mosquito breeding sites seem to have been ignored. The United Nations Food and Agriculture Organization’s former Engineer Ranjit Seneviratne has recently revealed some myths and ineffective practices that were being followed specially by state institutions to control the epidemic. He gives some enlightening information and practical methods which are useful to both ordinary citizens and authorities in their battle against dengue.

“Various efforts are being made by the authorities and the Colombo Municipality personnel who are going around clearing plants and insisting that people who grow useful food plants like banana, Aloe Vera etc. should remove them – as well as flowering plants so useful to encourage bees and butterflies that are scarce in the city. This appears to be a sort of “knee-jerk” reaction, because if it were plants that harboured dengue-carrying mosquitos, then dengue should be rampant in villages with so much of vegetation there,” Mr. Seneviratne argues. “The reason for this is perhaps because plants are known to exude oils and bio-chemicals (much like humans exude salty sweat from the skin’s surface) and the dengue mosquitoes normally do not breed in such polluted water.”   

He says, on the contrary, dengue is rampant in cities that are densely populated and near schools – in other words where there are people and children who throw plastic yogurt and ice cream cups and plastic bags all over the place, as well as Thambili and coconut “shells”.   He emphasises the need for the authorities to insist that ice cream, yogurt, etc, should only be sold in paper cups (that could be easily torn to prevent water collection) and king coconut (Thambili) sellers should collect their “shells” in gunny bags – and be fined if they left them around.  

“Another source of clean water favoured by the Anopheles Aegyptus Mosquito (implicated in the spread of dengue) are plastic bags. Therefore it is in everyone’s interest that the authorities should eliminate plastic bags and insist that only paper or cloth, jute-hessian or woven leaf (Dumbara Mat “Pang” and Palmyrah leaf) bags be used,” Mr. Seneviratne said.  

He also points out that public places where water collects are roads, because in Sri Lanka, people allow water from their properties to flow into the road, causing the road to break up and water to collect in small pot-holes. This is contrary to what happens in other countries where owners would be fined for such offences.    The other place where water collects is public drains, because we the uncaring public, carelessly throw rubbish into drains, blocking the flow of water. The present practice is to spray toxic chemicals into these drains. As the drains are not water-tight, these harmful chemicals leak into ground water and could poison us. The effect is not immediate, but these chemicals are known to gradually accumulate especially in the fat cells and over time could cause cancer and other non-communicable diseases (NCDs).  

The FAO expert says a simple and inexpensive solution is to spray used engine oil (most of the harmful additives in the oil are “burnt up” in used oil). “The oil forms a film on the surface and the larvae of the mosquitoes during the pupal stage (when they are shaped like “commas”) are air breathers and come to the surface to breathe. The oil chokes the breathing tube and kills the pupal stage mosquito larvae.  

Mr. Seneviratne also submits a more technical solution that could be implemented by the authorities to control dengue mosquitoes. He encourages the use of the “Sterile male” technique which was successfully used by the FAO to eliminate the “New World Screw Worm” (whose larvae bore into living flesh killing their host). This was done when there was an outbreak in North Africa from meat imported from South America and also from a West Indian Island that was infested, to prevent it from migrating to main-land USA.  

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