The short heavy showers followed by bursts of sunshine that we are currently experiencing have left pools of water in drains, gutters, and clogged canals and provided ideal breeding grounds for the dengue carrying vector. The result? A steep upward curve in dengue throughout the island especially in highly congested urban and semi-urban areas.
The Sunday Observer sought the help of one of our most experienced experts in dengue disease and dengue management who is also the Founder Clinical Head for Clinical Management of Dengue and Dengue Haemorrhagic Fever (DHF) and currently Consultant Paediatrician Nawaloka Hospital, Negombo, Dr. Lakkumar Fernando, to find out how we can protect ourselves from this deadly disease that is preventable with simple easy to follow rules which require consistent adherence to keeping our environment clean.
Excerpts
Dr. Lakkumar Fernando
Q: According to recent media reports Sri Lanka is experiencing a surge in dengue cases islandwide. Do you agree?
A: This year the highest number of cases was in January and it was 10,000+ then it dropped to 2000+ in April and June and in July we are experiencing a steady rise.
Q: Do you think this could lead to an outbreak that could result in a dengue epidemic shortly if not contained immediately?
A: It is possible depending on a favourable weather pattern.
Q: Compared to other countries both developing and developed, how does Sri Lanka rank in your latest research surveys?
A: For preventive measures Sri Lanka is far behind countries like Singapore and our case numbers are still very high. But we are almost the best when it comes to rapidly improving clinical management and possibly has the lowest case fatality rate for countries experiencing Dengue Haemorrhagic Fever.
Q: Is the prevalence rate the same in all districts and regions or do they vary? If so, which areas show the highest cases at present?
A: The Western province still has close to 40 percent. Colombo district is the top most and Jaffna is second, surpassing Gampaha district.
Q:What are the main factors that have caused this? Is the current weather conditions one of them? If so, how?
A: Yes.
Q: Do you agree that the short, sudden showers followed by long periods of sunshine could provide the ideal breeding grounds for the dengue-carrying vector?
A: The biggest factor for an outbreak will be the weather pattern. Short showers with hot and humid climates in between are the worst. The increased in-between temperature shortens the mosquito maturation time and the extrinsic cycle of the Dengue Virus.
Q: Since many of us still don’t know what it looks like, tell us what specific features we should look out for in this mosquito.
A: It is a small, dark mosquito with white bands on its legs and a silver-white pattern of scales on its body. There are two types of aedes mosquitos that transmit dengue.They are Aedes aegypti that has two white bands on its thorax (back) in the shape of a lyre, whereas Aedes albopictus has only one white central band.
Q: I understand that it has certain times of the day when it goes in search of its meal of fresh blood. What are these times?
A: Usually from 6 to 9 am and 3 to 6.30 pm. Some countries have recently reported changes in biting times.
Q: Can anyone bitten by an infected mosquito get dengue?
A: No, most don’t develop the disease and will remain asymptomatic. Some can develop an almost non noticeable mild disease.
Q: Are some people more at risk of developing the disease than others? For instance, persons engaged in certain occupations such as dredging canals and swamps, cleaning drains, and those in the gem mining business? If so,why?
A: Yes, depending on their time and frequency of exposure in relation to the environmental density of the adult biting mosquito as well as their biting time. Not only what’s mentioned in the example, but even school children or others going for work are getting exposed.
Q: Age-wise, who are those most vulnerable to getting dengue if exposed to the virus?
A: No specific age group has a relative protection or vulnerability except that the below 6 months in dengue-endemic areas maternal immunity may have passively transmitted antibodies protecting the baby for up to 6 months. At the same time, such antibodies occasionally produce extremely severe diseases due to a phenomenon known as immune enhancement. As a result, infants either get very mild or very severe disease than the In-between.
Q: What are the symptoms to look out for in general?
A: Fever is an essential symptom in 99 percent or more and measuring it with a thermometer is the best way to be sure. Normal temperature is 37 centigrade or 98.6 Fahrenheit. In dengue it’s usually above 38C or 100+ F Fahrenheit. Severe headaches, pain behind the eyes, generalised body aches with muscle and joint pains are common. Nausea, vomiting, and abdominal pain may be seen in a few.
Q: What are the symptoms to look out for in general?
A: Fever is the most important. Generally above 100.F or 38C, headache, pain behind eyes, generalised aches and pains of the body or limbs, vomiting or nausea, abdominal pain.
Q: Are the symptoms the same for all or do they vary according to the age of the victim? For instance, what symptoms should we look out for in 1) infants 2) toddlers 3) primary school children 4) pre-adolescents?
A: Infants can’t complain and fever, refusing feeds, vomiting lethargy could be common. Toddlers will have fever and become less active. Bigger children will complain of headache, nausea, and aches.
Q: What about young people? At what age are they most at risk?
A: No particular age to be at risk to develop the disease but, inability to get them to adequately rest and be sufficiently hydrated from the time of onset of fever may pose as a risk.
Q: How vulnerable are elders over 65?
A: They are generally protected as most are home-bound and stay indoors, but if they develop the disease they are at a higher risk for severe disease as with age they also may develop other diseases like hypertension, diabetes, heart or kidney disease. However contrary to this interestingly if an elderly person has lived in a dengue-endemic area like Colombo or Gampaha for a long period there is also a chance that he has already had several attacks of dengue with different serotypes over the years and by now may have life- long immunity against all or most of the serotypes and be protected from dengue when they are old. One can theoretically develop only about four times as each serotype gives lifelong immunity against that serotype. Some or all of these infections may even be asymptomatic as the majority of those who get infected will not develop symptoms. Usually, the first infection with dengue is mild and the second is usually the most severe in general; the 3rd and 4th could again be less severe than 2nd.
Q: What about pregnant women? Can the foetus be affected in a woman exposed to the virus?
A: Dengue is not known to produce congenital diseases unlike other viruses but has a higher risk of abortions.
Q: Will it affect his/her development and result in lower IQ and cognitive function
A: No, nothing like that is reported.
Q: What are the adverse impacts on the mother?
A: Pregnant mothers with Dengue are a high-risk group and if dengue is detected or suspected they have to be immediately admitted even on day one for more careful monitoring and the best outcome. The increased bleeding tendency can put them at a high risk if it’s close to delivery as both vaginal or caesarean sections are associated with bleeding. In managing pregnant dengue patients the mother’s life should be the priority all the time. Clinical decision-making should be based on such intention.
Q: So how do we protect ourselves against this virus? Are there Dos and Don’ts drawn up by the Health ministry that we can follow?
A: Clean your environment to get rid of mosquito habitats and breeding places and sustain this activity without making it a knee-jerk reaction after a dengue death or a case in the family. Be aware of how to avoid bites and don’t forget protective clothing and mosquito repellents too can make a significant difference in addition to other measures.
Q: Are contaminated environments a cause for concern in dengue acceleration? If so, for how long can the mosquito larvae remain in the soil to infect those exposed to it?
A. Larva cannot survive for long- mostly for less than a few days, but eggs can for many months, even close to one year. One worrying observation is the ability of the larvae to survive in brackish water with high salinity like in the lagoons.
Q: I understand that the WHO and UNICEF have approved a vaccine to prevent dengue. Where is it available? Can underprivileged persons get it free of charge?
A: The WHO recently pre-qualified the Qdenga vaccine by Takeda( a Japanese American product) and it’s recommended for areas of Dengue with high prevalence. At least the western province of Sri Lanka should be qualifying for that. Its efficacy against all four serotypes still lacks sufficient evidence and the duration of the effectiveness or sustainability of protection is still under study. However, evidence suggests it is very effective in controlling epidemics due to some serotypes of dengue. It may not be the perfect vaccine or the perfect solution we are looking for in a dengue vaccine and I don’t think such a perfect solution is near either. We need to decide whether we should make the best use of the imperfect solutions we have at hand or should wait without knowing when we will have a permanent solution. The vaccine has been licensed in over 35 countries which does not include Sri Lanka and our regulators are currently assessing its usefulness to our country. It’s necessary that we do it carefully, but also fast enough. The cost-effectiveness of vaccines will depend on the price we will get them for and where we can place them in our priority order. All these will need wider careful decision-making and negotiation for its price.
Q: For how long is the period of immunity the vaccine can give? Days? Months? Years? Or does it offer lifelong immunity?
A: The available data does not show sufficient promise that available vaccines will give life-long immunity and the need for boosters to keep the protection is the more likely prediction.
Q: Sri Lanka has a rapidly aging population. What is your prognosis for the Lankan community in the fight against dengue in the next few years taking into account the recent decision to free up the skies and encourage travelers from even dengue-affected countries to come to Sri Lanka?
A. Sri Lanka has enough dengue acses, and international travel is a basic need of the world today. Being one of the hot spots for dengue, it’s only a laughing matter worrying about travellers coming here from other dengue affected countries. Stopping such will almost have near zero benefit for us in every aspect.
Q: How many reported cases of dengue are imported from visitors from infected countries and how many are indigenous transmissions? Do you have any records?
A: No credible reports as such, but like in most viruses the genomic analysis will show the various origins of the viruses based on the countries the same has been reported previously. But for a country like ours with a history of having dengue for decades knowing this is of limited value.
Q: Is there a target for a dengue zero zone or country under the global sustainability program?
A: The WHO has announced its target to have zero deaths due to dengue by 2030. Sri Lanka can be one of closest to such even beating Thailand this year. However the way things are in the rest of the world this doesn’t seem easy.
We will never be able to eradicate the mosquito and make another tough species extinct the way nature behaves and reaching zero mortality will be possible only through a newer perfect vaccine which is unlikely to be that close. Best clinical management through good understanding of the disease is the best option we have at hand at present. Severe dengue that leads to death is largely caused by the clinical entity called Dengue Haemorrhagic Fever (DHF), and I believe DHF to be largely a “Predictably Treatable” disease.
Q: What are the gaps you see here in delivering quality care for dengue patients?
A: Currently Sri Lanka is one the world’s best with regard to its mortality rate due to dengue which is 0.04 percent percent at present. Making it zero or near zero need making ‘no mistake’- in the policy
The avoidable delays of making an early diagnosis, not doing the best tests early, being complacent knowing that deaths are rare and taking unnecessary chances, using NSAIDS or Steroids to bring down fever even ignoring the risks in a dengue endemic area and insufficient measures to make caregivers more accountable are gaps that need attention.
Q: As an eminent expert on this subject, share with us some of the recent inputs by the college of infectious diseases on better management of dengue patients. I’m told there is a booklet issued to all doctors to help identify cases and channel those with positive symptoms to the right persons.
A: The professional colleges of Paediatricians and Physicians have published guidelines for children and adults and SLMA has produced guidelines on dengue in Pregnancy. I had the opportunity to contribute to all there. With knowledge sharing Sri Lanka’s clinicians have got together to bring down our death rates due to dengue over 200 fold within just over three decades.
Q: How is dengue tested? Briefly walk us through the process.
A: The best is using a rapid Dengue Antigen Test by dropping a few drops of blood onto a test strip and visually examining it to see the appearance of a line showing positivity at 20 minutes. This doesn’t even need a lab to pick up well over 95 percent of cases if done after 20-30 hours from the time of onset of fever above 38 C.
Q: Are there different stages for dengue to develop? If so, what are they?
A: Dengue is generally a 7-8 day illness. All have a febrile phase and a recovery phase and a minority (>25 percent) have a phase called “critical phase” or a leaking phase in between. Most severe dengue cases are inside this 25 percent and they are the Dengue Haemorrhagic Fever Group. The febrile phase lasts 2-5 days, the critical phase only for 24-48 hrs and recovery phase is 3-5 days. Critical phase is the most dangerous phase.
Q: At what stage should a patient be rushed to hospital?
A: Just before or as early as possible in the critical phase or in high risk patients such as infants, elderly, obese, those with other illnesses.
Q: Your advice to all our readers out there on how to minimise risks of exposure to this dangerous disease that could have fatal results.
A: If you need zero risk, be aware and do whatever possible to avoid being bitten by a dengue mosquito. Have a plan. If you get a fever use a thermometer to measure it. If you notice a fever of >100F or 38C at least twice, get a rapid Dengue NS1Antigen test done from a proper credible laboratory at 20-30 hrs time from the onset of fever.
There is >95 percent chance that this test will make an early reliable diagnosis. With this go to a qualified doctor. (Unfortunately I am afraid to tell that they should first go to the doctor to ask when to take the test, as some doctors may not advise testing at this time period). Get doctors advice and treatment and make sure the treatment you received has no NSAIDS or Steroids. (Ask the doctor). In the FBCs show that the platelets are rapidly dropping towards or pass 100,000, plan on getting admitted for best case management.
