Viral awareness

  • Health
  • Sunday, 27 Apr 2003

Consultant paediatrician Datin Dr REBECCA GEORGE offers her insights about a disease that may not appear to be as pressing as SARS, but continues to exact its toll in our population – dengue fever

THESE are the days for the latest killer virus, SARS. What it is and how it is to be tackled is not known as yet. This time again the Asean countries have been hit, but increased travel to and fro has caused the virus to spread to the West as well.  

In the past five years Malaysia has experienced the fury of other new viruses – the Nipah virus has come and gone, as has the Echo virus. I say “come and gone” because virulent as they were, we managed to get on top of these viruses and they were controlled. 

But what about that “old” dengue virus? This virus was known in the Malayan Peninsula since 1901. However, the deadly haemorrhagic features were described only in 1962 from Penang, and the first major epidemic occurred in Selangor in 1973. Ever since then, in spite of all the research and conferences to discuss dengue, this disease has persisted and now 30 years later it is still present in our country and claiming lives.  

Fogging eliminates adults mosquitoes but do not affect breeding sites.

Having been a consultant paediatrician at the Kuala Lumpur General Hospital and later an Associate Professor at one of our medical schools, I had been actively involved with the dengue problem, including when the first large epidemic occurred in 1974 in Selangor.  

I gather that recently there has been some increase in the number of dengue cases. In any event, SARS has hogged the limelight. I have no doubt that with the international focus on it, we will get on top of SARS. However, it appears that dengue is here to stay. 

Dengue is a mosquito-borne viral disease. The virus evolved from a forest cycle involving lower primates and canopy-dwelling mosquitoes in the region, including in the Malay Peninsula. As such it is practically impossible to completely destroy either the virus or the mosquitoes. 

There are two species of the Aedes mosquito that can transmit the virus. The Aedes albopictus, large numbers of which exist in the forest fringes, was one connecting link that transmitted the virus from primates to rural humans.  

The increase in migration of rural folk moved the virus to the towns and cities. The albopictus is of Asian origin. The Aedes aegypti, the principal epidemic vector of dengue, is thought to be of African origin. It had spread to the “New World” probably as a result of the slave trade. Because of commercial concerns and other interactions, about the time of World War II, the Aedes aegypti spread to Asian countries probably through boats, ships and even aeroplanes. 

Over the years, this species became closely adapted to humans and acquired a preference for feeding on human blood. It became a very efficient epidemic vector of the dengue viruses. It is a day-stinging mosquito that prefers the cool interiors of houses and offices. Its eggs and larvae are found in clear, still water found in vases, empty flower pots, discarded cans and the like, and very commonly in puddles, rubbish heaps and in water that has collected in discarded plastic bags. 

Education campaigns on denguq help spread awareness of the disease and can encourage all to take measures to destroy breeding sites of mosquitoes.

There are four dengue viral strains: DEN I, DEN II, DEN III and DEN IV. All four strains can produce the initial febrile illness or dengue fever (DF), or the severe and potentially fatal (if not properly treated) dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS). 

It must be clarified that a severe form of dengue can occur when a new virulent strain is newly introduced. Infection by one strain will produce antibodies that will give protection to that infection only. The patient can continue to be infected by any of the other three strains. When this happens, an antigen and antibody reaction takes place and very severe manifestations can occur (secondary infection).  

Since the severity of the illness depends on the level of antibodies, it is the healthy children and young healthy adults that get the severe form of the disease. In cases where the viral strain is very virulent, it can cause severe symptoms at even the primary infection stage. 

The persistent jungle-cycle infecting the primates, and the fact that currently there is no specific drug available against the virus means we have to rely on preventive measures and on early recognition of the disease to effectively treat those struck down by the disease. Although there is a vaccine, it is still under trial and as such it's not available for regular use. 

In the 1974 epidemic and in the early 1980s, when dengue epidemics started becoming more frequent, a concerted effort was made by all concerned under the umbrella of the Health Ministry to deal with the problem. The clinicians (mainly the paediatricians as children were the main victims of the disease) and members of the Virology and Microbiology Divisions of the Institute of Medical Research and of the University of Malaya worked tirelessly with City Hall and other local authorities at controlling the spread of the disease and in dealing with the patients struck down with it.  

In those days, we knew little about the manifestations of the disease. In the late 70s and early 80s, creditable work on the problem had been done in Thailand. Malaysian paediatricians and health workers benefited from the many clinical papers published by Thai paediatricians and from the studies of effective preventive measures adopted by the Thai Health Authorities. 

Malaysian paediatricians also carried out extensive studies of the disease and there was a lot of interaction with their counterparts in the region, including Thailand and the Philippines. Local microbiologists made available tests for early detection and confirmation of the infection so that with early confirmation, treatment could be promptly provided before the severity of the illness manifested. 

Due to persistent ongoing preventive methods, Thailand managed to control the incidence of dengue cases. These methods that we adopted and developed included education of school children and the general public. Young doctors at the ground level were taught to recognise cases of dengue early and to manage them correctly so that the disease does not progress to the more serious stages.  

Today, most of the cases detected in Thailand are being treated in day care centres and monitored and adequately managed so that they do not progress into severe cases. Thailand persisted with what had been learnt in the late 70s and early 80s and their case fatality rate became, relatively speaking, insignificant. 

In Malaysia too we had achieved significant success in controlling the incidence of the disease. However, recently, the occurrence of the disease seems to have increased.  

In the mid-80s, we had brought out certain guidelines: A dengue alert was to be made whenever the number of cases started to rise or a new strain was introduced into the country, and the public alerted about a possible epidemic. 

Effective and continuous preventive measures had to be taken. The clearance of rubbish heaps and discarded plastic bags and the like was carried out regularly, at least on alternate days. Regular checks of houses and gardens for Aedes breeding sites –disused flower pots, discarded cans, flower vases – had to be made. Fines were imposed. Suitable measures for destruction of Aedes larvae and adult mosquitoes were carried out on a regular basis. 

Schoolchildren were taught about the vectors of dengue infection and their breeding sites.  

They were encouraged to help keep the school premises clean. The teaching staff had to do regular inspections for breeding sites. There were instances where several school children were taken ill with dengue, and the source was traced to stagnant water in broken down floors and tanks in school toilets. 

The emphasis was to educate the public by regular talks over the radio, television and articles in the newspapers. People were to be kept fully aware of what was happening as a reminder that another epidemic could be on them before they knew it. 

Every death that occurred had to be investigated thoroughly and a report given to the Ministry. By this method, many atypical presentations of the diseases were detected. We came to know that the virus can enter practically all the systems of the body. Severe disease affecting the liver, the respiratory system and the nervous system were confirmed. The dengue virus has even been isolated from the brain. 

Accordingly, others and I have been alarmed that the lessons learned in the 80s appear to have been forgotten. Newspaper readers will recollect the daily dose of anti-dengue slogans through radio and television. However that petered out. 

Some time ago, before the NAM Conference, the Datuk Bandar made a statement that the number of dengue cases in the city was worrying. “There is to be fogging exercises in KL,” he said, “until the end of the month.” He himself has stated that this will only get rid of the adult mosquitoes, and will not affect the breeding sites.  

The Datuk Bandar has stated that the eradication of mosquitoes is the responsibility of the residents and this could be done by keeping the surroundings clean. But who is responsible for clearing clogged and broken down drains?  

I live in Ukay Heights and can state without fear of contradiction that there are any number of such drains in and around the Hulu Kelang areas where rain water collects and remains stagnant and makes ideal breeding sites for Aedes. And Hulu Kelang and Ukay Heights are supposed to be some of our better suburbs! 

A press release from the office of the Director General of Health dated January 30 states only 1.01% (of residential houses inspected) of breeding sites were found in houses, whereas 8.1% (of garbage disposal sites inspected) were from garbage disposal sites. The Ampang Jaya Municipal Council should drive around Ampang point and Ampang Jaya where the “ordinary folk” live and shop. Piles of garbage and plastic bags are left around without being regularly and/or effectively collected. This I am afraid appears to be the position in many of our suburbs and villages. There are many small eating shops in these areas. Flies also abound and they can spread bacteria to the open air restaurants. But that is yet another story. It is gratifying that in some suburbs like Subang Jaya, private companies have started cleaning campaigns to get rid of Aedes. 

The centre of the city is kept reasonably clean. But there are the suburbs. The Aedes mosquitoes are great travellers. They can travel to the city in motor vehicles, in briefcases and in food baskets and keep the epidemic going.  

Educating school children, the teachers and the public should be an ongoing project, not intermittent. All medical students should be continuously taught about this potentially dangerous virus. There are Clinical Practice Guidelines on the early recognition and management of the dengue virus infection in babies and children produced by the Ministry of Health, the Academy of Medicine, and similar booklets for the management of adults are being prepared. How many doctors are aware of these booklets?  

Today, many doctors and nurses are trained in overseas institutions where dengue is not a problem. So, with many of the new medical colleges twinning with overseas colleges, how do we educate these young doctors, who in all probability know very little about recognition and management of dengue? 

What about the doctors in the numerous private hospitals? Are they keeping themselves abreast with the latest developments of the disease? Responsible bodies like the Malaysian Paediatric Association could be sought for help to keep the relevant medical community informed. Educating young doctors and nursing staff should be a regular and ongoing process. 

The medical and health systems in Malaysia have been the envy of the region. WHO is on record as praising it. However, dengue appears to be a blot on our otherwise good record. 

These are urgent problems to be dealt with. We cannot afford to be complacent. As a mother, grandmother and a paediatrician, I call upon all concerned to exert greater efforts so that our health authorities are able to give weekly statistics showing how the number of dengue cases are coming down with increased control methods. 

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