Mosquito-borne diseases become a climate reality in the warming Pacific | Health info

Climate change forecasters have warned for years that the warmer, wetter world created by the climate crisis will lead to a surge in mosquito-borne diseases, such as malaria and dengue fever.

Experts say that in the Pacific Islands, such predictions are now coming true.

Regional development organization the Pacific Community says that between 2012 and 2021, its Pacific island members have recorded 69 dengue fever outbreaks, 12 Zika virus outbreaks and 15 Chikungunya virus outbreaks. The diseases, which can sometimes be fatal, are all transmitted by mosquitoes that thrive in hot, humid conditions.

Disease surveillance by the World Health Organization shows that in the Solomon Islands, for example, cases of malaria increased by 40% between 2015 and 2021. In Papua New Guinea, the incidence of malaria increased by 5% over the same period, with a 25% increase in related deaths.

“We are really concerned about vector-borne diseases, mainly because they are a serious public health problem. Dengue fever is of growing concern because it can lead to dengue hemorrhagic fever, which can lead to death. Additionally, Zika has recently emerged and there is evidence that it can cause birth defects in babies,” Dr. Fiji.

Zika, which causes a rash, fever, headache, muscle and joint pain, Chikungunya, which causes debilitating joint pain, and dengue fever are transmitted by the Aedes aegypti mosquito which tends to bite during daytime.

“Climate change is an important factor. It has already been proven that vector-borne diseases are very climate-sensitive diseases. This is what can be seen in the region; they emerge after disasters, cyclones and when there is an increase in temperatures,” Saketa said.

The PacMOSSI project helps Pacific islands monitor and control mosquito populations. which have expanded as climates have become warmer and wetter (Courtesy of QIMR Berghofer Medical Research Institute)

Acting now is crucial, according to Tom Burkot, a professor at the Institute of Tropical Health and Medicine at Australia’s James Cook University in Cairns.

“If we just maintain the status quo, vector-borne disease outbreaks in the Pacific will likely become more frequent and numerous. To prevent this from happening, we need to invest in new strategies to control the mosquito(es) and treat or prevent infections in humans,” said Burkot, who leads an international partnership between island nations. of the Pacific and health and research institutions to find new ways to fight these diseases, Al Jazeera told Al Jazeera.

Vector-borne diseases occur when people become infected with parasites or viruses carried by vectors, which are usually mosquitoes and other blood-sucking insects, and are more prevalent in tropical and subtropical regions of the world where the warm climate provides the ideal conditions for them to thrive.

In PNG, located east of Indonesia and north of Australia in the South Pacific, the average temperature hovers around 25°C (77°F) all year round and the humidity ranges from 70 at 90%.

Vector-borne diseases are “a significant public health problem in coastal PNG. Malaria is the main vector-borne disease of concern; more than 87% of the malaria burden in the Western Pacific region comes from PNG,” Dr Moses Laman, deputy director of science at the PNG Institute of Medical Research in the Eastern Highlands province, told Al Jazeera. from the country.

“Malaria was on the decline in PNG until about 2014-2015. But epidemiological field studies and monitoring and evaluation of the national malaria control program by the institute showed a resurgence of malaria after this period,” he added.

The main factors for this resurgence include insufficient disease surveillance in the country and a lack of resources and capacity in the health system to respond effectively.

“Very suitable”

Dengue fever is also becoming a significant concern.

Without an effective vaccine or dedicated treatment, the fever has been gaining ground in densely populated urban areas, not only in the Pacific islands but also in the hottest parts of the world in recent decades, according to the WHO.

Dengue fever can cause a wide range of illnesses and complications, ranging from severe flu-like symptoms to excruciating abdominal pain, vomiting, chronic bleeding, difficulty breathing and organ damage.

“In the Pacific, malaria is only endemic in three countries, while diseases such as dengue fever and Zika can potentially spread to all Pacific island countries.

“Aedes vectors of dengue fever are highly adapted to human environments, so the potential for outbreaks is linked to urban areas, as (they) feed almost exclusively on humans and their larvae are mainly found in artificial containers” , said Burkot of James Cook University. explain.

The spread of the Aedes mosquito has led to more debilitating diseases in the warming Pacific islands (Courtesy QIMR Berghofer Institute for Medical Research)

The Solomon Islands, a sprawling archipelago of more than 900 islands southeast of PNG, has seen a number of dengue fever outbreaks in recent years.

A large outbreak in the capital Honiara in 2013 affected nearly 2,000 people. It followed heavy rains in the rainy season and an earthquake and tsunami, which devastated parts of the country in February. Three years later, there was an even larger dengue epidemic, affecting more than 12,000 people. Of these, some 877 patients required hospitalization and 16 people died.

Malaria is common in rural villages on the country’s outer islands, such as those in Isabel Province, particularly during the rainy season from November to April.

“We have cases of mosquito-borne diseases – especially right now it’s on the rise. It is indeed a threat. Mosquitoes live around the village, near ponds and open drainages – that’s where they breed,” Rhoda Sikilabu, the premier of Isabel province, told Al Jazeera.

“There have been very high cases of malaria in my village of Horara. I had malaria three times since last year,” she said.

The climate crisis is creating ever more favorable conditions for disease-carrying mosquitoes.

Over the coming decades, Pacific island nations will experience higher air temperatures and more extreme heat waves and rainfall, according to the Intergovernmental Panel on Climate Change’s sixth assessment released in February. from last year. Other factors, such as insecticide resistance, population growth and the increase in the number of people traveling, will also influence the increase in cases.

Burkot says many Pacific island countries do not have enough human and financial resources to tackle rising disease. The collaborative PacMOSSI project, which brings together Pacific island countries and institutions – including the WHO, the Pacific Community, the QIMR Berghofer Institute for Medical Research and James Cook University – is working to meet the challenge.

It plans to strengthen the training of health workers across the region, support the health capacity of governments and work with local communities on the control of areas affected by mosquitoes.

Prevention is vital, for lack of effective vaccines (the new vaccine against malaria is not yet available in the Pacific region). In PNG, “the mainstay of vector-borne disease prevention is long-lasting insecticide-treated bed nets. These are provided nationwide every two or three years by the national health department and Rotarians for Malaria,” Dr. Laman said.

However, he added that, in recent years, studies of nets used in PNG have revealed problems with quality and ability to filter out mosquitoes. As a result, the country was now procuring better quality bed nets that met WHO standards from new sources.

Mosquito-borne diseases are prevalent in cities where there are plenty of places for insects to breed (Catherine Wilson/Al Jazeera)

Reducing the presence and threat of mosquitoes is a key objective of the work carried out by the Pacific Community and the PacMOSSI project.

This means helping countries improve “mosquito surveys, to find out what type of mosquitoes they have and their distribution, and whether there has been foreign introduction of other mosquitoes into the area”, Dr Saketa said. .

“One of the main ways to control mosquitoes is to remove breeding sites, clean up and destroy breeding areas.”

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