Shiloh
Editor, Senior Moderator
Source: http://www.nst.com.my/Current_News/NST/Sunday/Frontpage/2218630/Article/index_html
2008/04/20
War on dengue: Are we getting it wrong?
By : P. SELVARANI and SONIA RAMACHANDRAN
Malaysia has been fighting the dengue scourge for more than four decades, yet the number of cases is increasing. P. SELVARANI and SONIA RAMACHANDRAN find out that this may simply be because we may have been doing it wrong all the while
COMPLACENCY, coupled with the wrong strategy in fighting the menace, could be the reason dengue cases are on the rise despite 30 years of vector-controlling measures such as fogging.
"We have been fogging and fogging for the last 30 years and if the number (of cases) is steadily increasing over the years, surely something is not right?" said Prof Dr Sazaly Abu Bakar, director of the World Health Organisation Collaborating Centre for Arbo-virus Research and Reference (Dengue Fever/Dengue Haemorrhagic Fever) at Universiti Malaya.
Dr Sazaly said Malaysians had grown complacent because the dengue problem had been prevalent in the country for so long and, as a result, they were no longer serious in addressing the issue.
For example, he said, the current vector-controlling measures were adopted from an American model developed some 30 years ago and it was only effective in killing the adult mosquitoes but not the larvae.
"We have been using a model from a country that is different from us and where dengue is an imported disease, without actually knowing if it is the right one.
"Are we using the correct concentration of chemicals? Perhaps our method of spraying is not effective or that over the years, the mosquitoes have evolved and grown resistant to the chemicals?" said Dr Sazaly, who also heads the Department of Medical Microbiology at Universiti Malaya.
"No one knows the answers because we have not done any studies. We need to study these factors and devise a strategy based on it."
He said funding was sorely lacking for local scientists to carry out research.
"We have the expertise to do a lot of research but we are not getting the funding. Dengue is our problem. It is endemic here and yet we are not spending any money on it."
Dr Sazaly said one of the more effective ways to control the problem was for the authorities to take daily and weekly samples of mosquitoes to find those carrying the dengue virus and reduce their population without disturbing the ecological system.
"There should be continuous monitoring and surveillance and only then can we predict and preempt an outbreak before it occurs. Right now, we do not even know the genetics of our mosquitoes here.
"The fire-fighting methods that the local authorities are employing now, such as fogging an area when a case is reported, are ineffective."
Dr Sazaly said there was cause for concern over the way the dengue problem was being addressed as it was becoming a worldwide phenomenon due to global warming.
In Malaysia, the number of dengue fever cases and dengue haemorrhagic fever has risen from 518 cases in 1973 to 45,856 suspected cases last year.
"The danger is that for every patient confirmed with dengue, three more go undetected because it is asymptomatic."
Dr Sazaly said there was a need to come up with a faster and more accurate method of diagnosing dengue.
At present, a person who has been infected with dengue will only show symptoms on the second or third day but the diagnostic tests will only be able to confirm the infection on the fifth day when the antibodies appear.
By this time, however, his family, friends and neighbours may have been infected.
"We are still relying on old lab tests which require you to have a fever for at least five days before you are confirmed to be positive for dengue. By then, your condition may be severe and by the time you go to hospital, it may be too late.
"We have to improve not only our vector-control methods but also ensure early detection of the infection, like coming up with a cheap self-diagnostic kit."
Dr Sazaly said although the technology was available now, it was expensive and could only be done at referral centres such as the University Malaya Medical Centre and the Kuala Lumpur Hospital.
"We need to come up with our own diagnostic kit so that we can bring the cost down. Right now, it's all imported and developed by the Americans, Australians and French because all the major research on dengue is being done by them. They don't even have dengue!"
He said of the 45,856 suspected dengue cases last year, only 14,354 were confirmed positive.
"Because of the weaknesses in our detection system, we could not positively identify the remaining 33,000 as dengue cases. So, these people, who are walking out there, could be infected and not know it."
Studies have shown that a person is more likely to develop dengue haemorrhagic fever, which can lead to death, if he has already been infected with dengue fever before.
"People need to know their dengue status. If you have had dengue fever before, then you have to be careful because the second time you get it, the chances are high that it will develop into haemorrhagic fever.
"But then again, not everyone who has a second infection will die. We need to study the factors which contribute to dengue haemorrhagic fever and who are more susceptible."
Those who are obese, diabetic or over 60 years old are considered to be in the high-risk group as they have a higher chance of developing dengue haemorrhagic fever.
"We need to study why this group is predisposed to it and to do this, we need to study their genetic background. If we know that not everyone will die of dengue, at least we can focus on the type of patients we need to manage.
"If we can spend some money to research this, we can develop drugs to prevent these deaths. And if we have drugs to manage dengue, we won't have to vaccinate 29 million people."
He said it was not cost-effective to develop a vaccine for a large number of people when only a certain percentage of them were at real risk of dying from dengue.
Dr Sazaly said the proper management of dengue patients was another area which was often overlooked by doctors.
As there was no blanket treatment that is suitable for all dengue patients, doctors need to treat each patient based on the symptoms.
Dr Sazaly said there was also a misconception about dengue haemorrhagic fever.
"Although it is called dengue haemorrhagic fever, it is actually leakage of body fluids and not bleeding as generally perceived. You don't die of bleeding. What happens is that you have vascular leakage which will affect your internal organs.
"When you have vascular leakage, you should be judicious about the fluid management in the patient. If you give too much fluids, the patient can die. Doctors should be taught how to manage dengue patients properly."
He said doctors should not rely solely on the platelet count to determine the severity of a patient's condition.
"The most important thing to look at is the haematocrit, which will give an indication of whether the patient is having vascular leakage or going through shock."
Dr Sazaly said a multi-pronged approach was needed to tackle the dengue problem, including funding more research by local scientists.
"It is hyper-endemic here and yet we are not putting our research efforts into it.
2008/04/20
War on dengue: Are we getting it wrong?
By : P. SELVARANI and SONIA RAMACHANDRAN
Malaysia has been fighting the dengue scourge for more than four decades, yet the number of cases is increasing. P. SELVARANI and SONIA RAMACHANDRAN find out that this may simply be because we may have been doing it wrong all the while
COMPLACENCY, coupled with the wrong strategy in fighting the menace, could be the reason dengue cases are on the rise despite 30 years of vector-controlling measures such as fogging.
"We have been fogging and fogging for the last 30 years and if the number (of cases) is steadily increasing over the years, surely something is not right?" said Prof Dr Sazaly Abu Bakar, director of the World Health Organisation Collaborating Centre for Arbo-virus Research and Reference (Dengue Fever/Dengue Haemorrhagic Fever) at Universiti Malaya.
Dr Sazaly said Malaysians had grown complacent because the dengue problem had been prevalent in the country for so long and, as a result, they were no longer serious in addressing the issue.
For example, he said, the current vector-controlling measures were adopted from an American model developed some 30 years ago and it was only effective in killing the adult mosquitoes but not the larvae.
"We have been using a model from a country that is different from us and where dengue is an imported disease, without actually knowing if it is the right one.
"Are we using the correct concentration of chemicals? Perhaps our method of spraying is not effective or that over the years, the mosquitoes have evolved and grown resistant to the chemicals?" said Dr Sazaly, who also heads the Department of Medical Microbiology at Universiti Malaya.
"No one knows the answers because we have not done any studies. We need to study these factors and devise a strategy based on it."
He said funding was sorely lacking for local scientists to carry out research.
"We have the expertise to do a lot of research but we are not getting the funding. Dengue is our problem. It is endemic here and yet we are not spending any money on it."
Dr Sazaly said one of the more effective ways to control the problem was for the authorities to take daily and weekly samples of mosquitoes to find those carrying the dengue virus and reduce their population without disturbing the ecological system.
"There should be continuous monitoring and surveillance and only then can we predict and preempt an outbreak before it occurs. Right now, we do not even know the genetics of our mosquitoes here.
"The fire-fighting methods that the local authorities are employing now, such as fogging an area when a case is reported, are ineffective."
Dr Sazaly said there was cause for concern over the way the dengue problem was being addressed as it was becoming a worldwide phenomenon due to global warming.
In Malaysia, the number of dengue fever cases and dengue haemorrhagic fever has risen from 518 cases in 1973 to 45,856 suspected cases last year.
"The danger is that for every patient confirmed with dengue, three more go undetected because it is asymptomatic."
Dr Sazaly said there was a need to come up with a faster and more accurate method of diagnosing dengue.
At present, a person who has been infected with dengue will only show symptoms on the second or third day but the diagnostic tests will only be able to confirm the infection on the fifth day when the antibodies appear.
By this time, however, his family, friends and neighbours may have been infected.
"We are still relying on old lab tests which require you to have a fever for at least five days before you are confirmed to be positive for dengue. By then, your condition may be severe and by the time you go to hospital, it may be too late.
"We have to improve not only our vector-control methods but also ensure early detection of the infection, like coming up with a cheap self-diagnostic kit."
Dr Sazaly said although the technology was available now, it was expensive and could only be done at referral centres such as the University Malaya Medical Centre and the Kuala Lumpur Hospital.
"We need to come up with our own diagnostic kit so that we can bring the cost down. Right now, it's all imported and developed by the Americans, Australians and French because all the major research on dengue is being done by them. They don't even have dengue!"
He said of the 45,856 suspected dengue cases last year, only 14,354 were confirmed positive.
"Because of the weaknesses in our detection system, we could not positively identify the remaining 33,000 as dengue cases. So, these people, who are walking out there, could be infected and not know it."
Studies have shown that a person is more likely to develop dengue haemorrhagic fever, which can lead to death, if he has already been infected with dengue fever before.
"People need to know their dengue status. If you have had dengue fever before, then you have to be careful because the second time you get it, the chances are high that it will develop into haemorrhagic fever.
"But then again, not everyone who has a second infection will die. We need to study the factors which contribute to dengue haemorrhagic fever and who are more susceptible."
Those who are obese, diabetic or over 60 years old are considered to be in the high-risk group as they have a higher chance of developing dengue haemorrhagic fever.
"We need to study why this group is predisposed to it and to do this, we need to study their genetic background. If we know that not everyone will die of dengue, at least we can focus on the type of patients we need to manage.
"If we can spend some money to research this, we can develop drugs to prevent these deaths. And if we have drugs to manage dengue, we won't have to vaccinate 29 million people."
He said it was not cost-effective to develop a vaccine for a large number of people when only a certain percentage of them were at real risk of dying from dengue.
Dr Sazaly said the proper management of dengue patients was another area which was often overlooked by doctors.
As there was no blanket treatment that is suitable for all dengue patients, doctors need to treat each patient based on the symptoms.
Dr Sazaly said there was also a misconception about dengue haemorrhagic fever.
"Although it is called dengue haemorrhagic fever, it is actually leakage of body fluids and not bleeding as generally perceived. You don't die of bleeding. What happens is that you have vascular leakage which will affect your internal organs.
"When you have vascular leakage, you should be judicious about the fluid management in the patient. If you give too much fluids, the patient can die. Doctors should be taught how to manage dengue patients properly."
He said doctors should not rely solely on the platelet count to determine the severity of a patient's condition.
"The most important thing to look at is the haematocrit, which will give an indication of whether the patient is having vascular leakage or going through shock."
Dr Sazaly said a multi-pronged approach was needed to tackle the dengue problem, including funding more research by local scientists.
"It is hyper-endemic here and yet we are not putting our research efforts into it.