KUALA LUMPUR: The emergence of DENV-3 as Malaysia’s dominant circulating dengue serotype has prompted health experts to remind the public that previous dengue infections do not provide complete protection against future infections.
DENV-1 and DENV-2 were the dominant circulating serotypes in Malaysia, but DENV-3 infections have risen this year.
Consultant paediatrician Dr Rakhee Yadav said that while a previous dengue infection provides long-term immunity against the serotype that caused it, children remain susceptible to the other three dengue serotypes, and parents should remain vigilant against DENV-3.
“There are four dengue serotypes. A child who has had dengue develops long-term immunity only against the serotype that caused the infection. They can still be infected by one of the other three serotypes,” said Dr Rakhee, head of the Department of Paediatrics at Damansara Specialist Hospital KPJ.
“When a different serotype becomes dominant, a larger proportion of the population has little or no immunity against it, allowing outbreaks to expand more easily.”
She said a subsequent infection with a different serotype may increase the risk of severe dengue due to a process known as antibody-dependent enhancement (ADE), in which antibodies from the first infection may unintentionally help the new virus infect immune cells more efficiently.
“The concern is that many people, including children, have little immunity against DENV-3 because it has not been the dominant strain for several years,” she said.
“One of the biggest misconceptions among parents is that a child who has recovered from dengue is protected for life.
“This is not true. Parents should continue taking preventive measures against mosquito bites even if their child has had dengue before.”
She also cautioned parents against assuming a child is recovering simply because the fever has subsided.
“The critical phase of dengue often begins around the time the fever goes away. This is when warning signs can develop,” she warned.
“Parents should seek immediate medical attention if a child develops persistent vomiting, severe abdominal pain, bleeding from the gums or nose, blood in vomit or stools, difficulty breathing, unusual drowsiness or restlessness, or cold, clammy hands and feet.”
Beyond recognising symptoms, Dr Rakhee said preventing mosquito bites and eliminating breeding sites remained the best defence against dengue.
“Where appropriate and in line with national recommendations, parents may also discuss dengue vaccination with their child’s healthcare provider, especially if they are aged four and above.”
The Health Ministry said the increase in dengue cases was driven not only by the emergence of DENV-3, but also by dengue’s cyclical transmission pattern, favourable weather conditions, rapid urbanisation, and persistent mosquito breeding grounds.
