Tharanya Arumugam and Aliza Shah New Straits Times 10 Feb 14;
KUALA LUMPUR: MEDICAL experts believe that the discovery of a fifth dengue variant in the country is just the tip of a greater risk to human lives.
Their worry is that the discovery of the latest dengue "Den-5" virus by researchers, was a portent of things to come.
Malaysia Medical Association president Datuk Dr N.K.S. Tharmaseelan said dengue researchers believed that the virus had been circulating in the jungles of Malaysia and Indonesia for possibly thousands of years without jumping into the urban transmission cycle.
They believed that that this may no longer be the case.
He said although the virus had not been detected in humans, except for one man in Sarawak who was found to be infected by the Den-5 virus several years ago, the need to keep the strain, as well as other possibly unidentified new dengue variants dormant in these obscure areas, couldn't be more pressing.
The Den-5 virus, exclusive only to Sarawak so far, is claimed to be the fifth dengue strain to be detected in the country.
It is the first new subtype in 50 years and those in medicine believe that this could be another challenge to the development of a dengue vaccine.
"This threat warrants better monitoring of dengue infections in Malaysia and the Indonesian archipelago, as researchers believe there may be more dengue variant to be discovered in the jungles of these two countries.
"The jungles are among the places where they believe dengue viruses evolved in primates, from ancestral viruses.
"The new subtype has only been found in Sarawak, where it could be circulating among macaques living in the forests, but its discovery calls for urgent preventive measures in controlling the disease," he said of the latest subtype.
Before the Den-5 discovery, dengue viruses identified in patients were exclusive to four serotypes-- the Den-1, Den-2, Den-3 and Den-4 viruses.
Dr Tharmaseelan told the New Straits Times yesterday that the Den-5 subtype was identified during screening tests on virus samples that were collected during an outbreak in Malaysia in 2007.
He said analysis carried out on the virus showed that the characteristics of the new variant were unique from the four existing viruses.
The virus was found in the blood sample of a man from Padawan, Kuching, by a group of researchers from the Institute of Health and Community Medicine (IHCM) of Universiti Malaysia Sarawak, headed by its director Associate Professor Dr David Perera.
A sample from the patient who has now recovered fully was sent for lab analysis and it is understood that the researchers managed to isolate the virus.
However, it remains unknown whether there are others who had been infected by the virus as there was no published evidence to suggest that the dengue strain could be found elsewhere.
He said lab tests on monkeys infected with Den-5 found that the virus induced different sets of antibodies from the primates compared with those that fight off the other four subtypes.
Dr Tharmaseelan said , there had been no solid evidence to establish the pattern of how the Den-5 virus is spread, unlike the clear "human-to-mosquito-to-human" cycle of the four strains.
In a reaction to MMA's assessment of the spread of dengue in the country Health Ministry deputy director-general of Health (public health) Datuk Dr Lokman Hakim Sulaiman dismissed the existence of the Den-5 virus.
"There is no new variant of dengue circulating in Malaysia or in the world.
"Our lab dengue virus surveillance showed no evidence of a new dengue strain... nothing was reported in the world scientific literature either," he told the NST.
The group of IHCM researchers who claimed to have discovered the Den-5 virus is expected to reveal their findings in April, which NST understands will include the full case of the man in Padawan who was infected as well as the virus' prevalence and symptoms in those infected.
It was reported that dengue fever resulted in 17 deaths throughout the country from January to Feb 2, this year, an increase of 240 per cent or 12 deaths compared with only five cases for the same period last year.
Throughout the period, 9,453 cases of dengue fever were reported nationwide, up 269 per cent or 6,894 cases, compared with 2,559 cases during the same period last year.
Health Ministry vector borne diseases section head Dr Rose Nani Mudin said analysis from blood samples, collected from dengue patients in 44 clinics and hospitals nationwide, showed that most of them were infected with the Den-2 virus (most dangerous) followed by Den-1, Den-4, and Den-3.
"Patients with Den-2 virus will show more severe effects, such as dengue shock syndrome and bleeding," she said.
