Page 22 - IB April 24

Health Health

DEALING WITH DENGUE

PACIFIC LOOKS TO NEW TOOLS

By Samantha Magick is, and we know their behaviours.”
The situation in the Pacific is particularly complex because
Climate change and increased urbanisation are driving an there are 12 different species that are capable of transmitting
increase in dengue and other mosquito-borne diseases and dengue.
the Pacific is responding with a suite of new interventions and “The thing about these 12 different mosquitoes … is
tactics. they all have slightly different behaviours. So the sorts of
The World Health Organization (WHO) says dengue is interventions that will work for one won’t work for the
endemic in about 125 countries this year, and dengue cases other,” Dr Burkot says.
and associated deaths increased by 30% in 2023 compared to PacMOSSI aims to assist Pacific Island countries with the
2022. most effective mosquito surveillance and control plans
The first few months of 2024 have seen French Polynesia possible, within the resource constraints faced by the region’s
and Samoa report an increase in dengue cases, with Samoa on health sectors. The project also provides research grants so
the brink of declaring a dengue fever outbreak as this issue countries can test strategies for themselves.
went to print. “What happens right now is in a lot of countries, they
The Pacific Community (SPC) says from 2012 to April 2023, do things to respond to a dengue outbreak, but oftentimes
there were 98 reported mosquito-borne viral outbreaks in the they don’t have the resources to be more proactive to try to
region, 72% of them dengue fever. reduce the risk of an outbreak occurring. And so we’re trying
SPC Senior Epidemiologist, Dr Salanieta Saketa says while to communicate what we know from other parts of the world,
the organisation has capturing outbreak reports through its where the evidence is strong, that if you do certain activities,
Epidemic Intelligence system for 40 years, “we struggle with you can reduce the risk of dengue transmission or you can
[getting] adequate or accurate data from countries.” reduce the scale of the epidemic,” Dr Burkot adds.
She says sharing and consolidation of data across the region, Expanding the toolkit
plus event-based surveillance (where information is gathered One of the most common, and visible methods of mosquito
from communities, social media and other sources in those control in many Pacific countries is outdoor fogging or
countries without lab testing facilities), would improve spraying of insecticides.
planning and implementation of dengue responses, and But Dr Burkot says generally this is not recommended, as it
importantly, early warning systems. can kill a lot of other insects, can lead to resistance in target
“Dengue and malaria are considered climate sensitive mosquito populations, and has only a transient effect.
diseases. So climate change is a real issue in the region, and “You spray it, you kill the mosquitoes that are flying at
it is affecting how vectors are, their behavior in terms of that moment in time. And then an hour later, or probably 15
procreating and being able to transmit disease.” minutes later, it’s not killing any more mosquitoes. So it’s a
WHO also notes the role of climate change—and in very expensive intervention.
particular higher average temperatures, extended rainy “Local governments like to do fogging because it’s
seasons and increased humidity— in influencing the incidence something that’s very visible to the population, ‘that your
of dengue. government is concerned about the health of the people, and
Changing climate and increased international travel has so we’re spraying insecticides to protect you from dengue.’
seen dengue present in parts of Europe and the US it has But all the evidence suggests that it is not a very effective
previously not been reported. approach.”
Mosquito mobility This month a study detailing a newer style of intervention,
Mosquitos are mobile. Their dried eggs can survive journeys the introduction of Wolbachia bacteria in Aedes aegypti
between nations, for example on the inside of a tyre, and mosquitoes in Fiji, Vanuatu and Kiribati, showed positive
hatch much later when they come into contact with water. results. The bacteria stops the mosquitos from being able to
Professor Tom Burkot of Australia’s James Cook University is carry the dengue virus, so they cannot transmit it between
Co-Lead of the Pacific Mosquito Surveillance Strengthening for humans.
Impact (PacMOSSI) project. He says many Pacific Islands have Wolbachia was introduced to select communities through a
not conducted a mosquito survey for some time. pilot in 2019. In the communities tested, “there was sufficient
“Distributions of mosquitoes change all the time. It’s really evidence that Wolbachia is well established in the mosquito
an important thing for countries to understand what species population” says Cameron Simmons, who is the Director of
they have present and the distribution of those species on the Global Implementation at the World Mosquito Program, a not
different islands. So when a dengue outbreak occurs, you … for profit operated by Monash University in Melbourne.
know what mosquitoes are on this island, where the outbreak Simmons says while Wolbachia has taken hold in the areas

22 Islands Business, April 2024