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The Health | august-September, 2020
| Probe |
SEARCH AND
DESTROY...
Eliminating the
larvae is vital.
Stop the apathy
Malaysians must shake off their indifference as the
large number of dengue cases poses a serious threat
BY KHIRTINI K KUMARAN
As the country grapples with
the Covid-19 pandemic, the
authorities are simultaneously
fighting an equally deadly virus
– dengue.
“Just because of Covid-19, don’t
forget about dengue. Dengue is always
there,” warned Director-General of Health
Tan Sri Dr Noor Hisham Abdullah recently.
His message to Malaysians – practice
search and destroy activities for at least
10 minutes a week to ensure the Aedes
mosquito does not have breeding places.
“Since January till Aug 11, 2020,
Malaysia has reported 66,689 dengue cases
cumulatively with 109 deaths compared
to 83,143 cases with 120 deaths in the same
period last year,” he told The Health.
Comparatively, during the same period,
the country saw 9,103 Covid-19 infections
and 125 deaths.
The World Health Organization (WHO)
estimates there are 100-400 million dengue
infections globally each year. However, the
figures in Malaysia show a reduction of
19.8 per cent or 16,454 dengue cases and a
decrease of 9.2 per cent or 11 dengue deaths
for this year.
The Senior Assistant Director of the
Vector Control Unit of the Federal Territory
of Kuala Lumpur and Putrajaya Public
Health Department, Dr Norazman Mohd
Rosli said: “At a glance, the reduction of
16,454 cases is good news for us.
“However, the number of dengue cases
has not come down steadily since the
beginning of May.
“At that time, weekly cases recorded
during EW19/2020 in Malaysia were 1,415.
Now, the weekly figure (EW34/2020) has
escalated to 1,718.”
Factors contributing to dengue
According to Dr Noor Hisham, the main
Dr Norazman and
Dr N Ganabaskaran
factor is poor environmental cleanliness
with the abundance of human-made
containers which provide places for Aedes
mosquitoes to breed.
Dr Norazman said from environmental
and human behavioural factors, the nature
of the Aedes mosquito contributed to the
ongoing transmissions.
“Female mosquitoes require blood to
produce eggs, so they bite humans. Infected
mosquitoes continue to transmit dengue
with each blood meal for the rest of their
lives,” said Dr Norazman.
The Aedes mosquito has also adapted so
that their eggs can survive dry conditions
for several months, only to develop into
mosquitoes once water is present. This
adaptation has made it very difficult to
eliminate mosquito populations.”
Dr Norazman also mentioned that usually
high strata buildings such as condominiums,
apartments and so on, which have high
population density, tend to be the hotspots
for dengue cases. Structural problems such
as blocked gully traps and gutters provide
breeding grounds for Aedes mosquitoes.
He also noted during the Movement
Control Order (MCO) many premises, such
as construction sites, were not adequately
maintained and provided breeding grounds
for the Aedes mosquito.
Vector control and prevention
Dr Noor Hisham stated to reduce the burden
of dengue in the country, the ministry had
implemented various prevention and control
activities at the national, State and district
levels.
“Through the National Dengue Task
Force Committee established since 2014 to
overcome the surge of dengue cases in the
country, the MoH together with six other
ministries and agencies coordinate targeted
dengue prevention and control activities
under the jurisdiction of each ministry.”
Dr Norazman explained vector control
included search and destroy, larviciding, and
fogging at localities with dengue outbreaks.
Meanwhile, prevention efforts are carried
out in areas with no dengue cases.
When the MCO was lifted, the Vector
Unit started its routine vector control and
prevention activities immediately.
“We even sent our health officers for
search and destroy at the schools before they
were reopened,” said Dr Norazman.
Apart from the conventional vector
control methods, Dr Norazman shared
that they also placed mosquito traps and
conducted outdoor and indoor residual
spraying of insecticides.
“Another new direction in vector control
is the Wolbachia Project. It was introduced
in Malaysia in July last year. Wolbachiainjected
mosquitoes were released in 11
localities, eight in Selangor and three in
Kuala Lumpur.
“So far, the results are promising. We have
seen a reduction of cases in the localities
in Kuala Lumpur. This year, Penang is also
involved with the programme along with
another three more localities in Kuala
Lumpur.”
The Wolbachia bacteria blocks the
replication of dengue virus in Aedes
mosquitoes. It involves releasing Wolbachiainjected
male and female mosquitoes into
hotspot areas to mate with wild Aedes
mosquitoes to replace and suppress the wild
Aedes population.
“Nevertheless, bear in mind that fogging
is not the only solution for dengue control