Dengue : The facts you should know

There are many questions and concerns relevant to dengue that the Sunday Times asked experts.

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By Kumudini Hettiarachchi

Is there a change in the disease pattern? Yes. From 2009 to 2016, Sri Lanka has faced DENV1 and DENV4. Currently what is wreaking havoc is DENV2. Experts say that the sequence of people who have earlier been hit by DENV1, now being exposed to DENV2 has caused the virulence to get worse.

There are four dengue virus serotypes – DENV1, DENV2, DENV3 and DENV4. Usually after being infected with one serotype, the person becomes immune to that but if he/she contracts a different serotype the vulnerability to and virulence of the disease are greater. The prevalence of DENV2 currently has been determined by sample testing.

The symptoms which need to be taken seriously – In the progression of the disease currently with DENV2, it is learnt that the platelet count drops quicker in Day 2, rather than in Day 3 as in the other three serotypes of DENV1, DENV3 and DENV4.

Those suffering from Dengue Haemorrhagic Fever go into fluid leakage quicker too on Day 2 instead of the usual Days 4 & 5. Experts are unsure whether this is a feature of DENV2 alone or whether it comes about when DENV2 affects a patient who has had an earlier infection with a different serotype.

Many doctors requested the government to ensure price control of a full blood count (FBC) test at around Rs. 200, so that it would be affordable to a majority of people.

This is while some doctors said that to ensure smaller numbers seeking treatment for dengue at hospitals and better management by short-staffed as well as overworked and exhausted junior doctors and nurses, people should be encouraged to get the Dengue NS1 Rapid Antigen Test done if there is high fever (>100F) between 18 and 24 hours of the onset of the temperature. If the government waives the taxes off the antigen test kit or the authorities themselves import the kits, the price could be kept at around Rs. 500 to 600. Then the people will do the test at their own cost and would also not be fleeced by laboratories.

Pointing out that some of the antigen test-kits are not of good quality, they reiterated that stringent action should be taken to stop those without approval from the National Medicines Regulatory Authority from flooding the market.

Have breeding places of the dengue mosquito changed? Yes. With the current conundrum being “nethi karanna be, vanda karanna be”, experts are of the view that while ensuring that there are no breeding grounds in and around homes, workplaces, construction sites, schools, tuition classes etc., what should be kept in mind is that these insects will somehow find alternative breeding grounds.

Mosquitoes in different parts of the country seem to have “adapted” to keep on proliferating, experts said.

All across the country – Experts are advising people to check unused toilets including squatting pans and also cisterns with water for mosquito breeding.

Western Province which is overwhelmed by dengue – the breeding spots are discarded receptacles and containers but could also be anywhere there is clean water. In some countries, studies have shown that breeding takes place both inside and outside houses. Usually, those checking homes look at the exterior, therefore, the people should do thorough checks within their own homes to destroy breeding spots.

Eastern belt including Trincomalee and Batticaloa – the breeding is taking place in shallow wells.

So the plea is to keep the eyes open for new breeding sites, while also examining the ‘traditional’ spots.

Is there a vaccine for dengue? While one dengue vaccine has been produced, there are other vaccines undergoing clinical trials across the world. Currently, Sri Lanka is part of one such multi-centre trial.

There are issues with the one-and-only dengue vaccine registered so far, it is learnt, with this vaccination not providing significant protection against DENV2. The World Health Organization (WHO) has recommended that it should be administered only to those above nine years old and especially to those who already have a past history of dengue infections.

Can dengue be prevented? Many lament that in Sri Lanka, there seems to be only “zero-prevention”. However, experts stress that if a concerted effort is made by each and everyone – the people and all the official stakeholders, this will not be an impossible task.

Even if eradication of dengue and the dengue mosquito may not seem possible in the near future, simple but prompt action could bring down the numbers affected by dengue.

When there is a red signal of one dengue patient seeking treatment, immediate action in the form of a rapid deployment team with a SWAT-like reaction should take place – seeking out the house and neighbourhood from which the person has come and carrying out mopping up operations, before the dengue-bearing mosquito has left the area. This would also prevent other mosquitoes which have bitten the new patient and become carriers of dengue to be destroyed. Rapid deployment and a clean-up and fogging of the area would stop the spread of the disease.

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