- Germany's Oktoberfest opens under tight security after attacks
- Environmental protesters block French cruise liner port
- Hezbollah in disarray after Israeli strike kills top commanders
- No place like home: Biden hosts 'Quad' leaders
- One dead, 7 missing as heavy rains trigger floods in central Japan
- Zelensky says no UK, US go-ahead to use long-range missiles
- New Zealand edge Australia 31-28 in Bledisloe Cup thriller
- Japan orders evacuations as heavy rains trigger floods in quake-hit area
- New Zealand pilot freed in Indonesia after 19 months in rebel captivity
- Hezbollah in disarray after Israeli air strike kills top commanders
- The BYD Seal Hybrid U DM-i AWD in a practical test by journalists
- Leading climate activist released from Vietnam jail
- Ethiopians struggle with bitter pill of currency reform
- Sri Lanka votes in first poll since economic collapse
- Feminist author warns of abortion disaster if Trump wins US election
- US city of Flint still reeling from water crisis, 10 years on
- Arsenal's mean defence faces acid test to shut out Man City again
- Late surge lifts Thailand's Jeeno to LPGA Queen City lead
- DeChambeau says PGA's Ryder Cup decision 'just the start'
- Alcaraz defeated on Laver Cup debut
- Postecoglou embraces 'struggle' to make Spurs a success
- Nice hand 'ashamed' Saint-Etienne 8-0 Ligue 1 mauling
- Boeing CEO says ending strike 'a top priority'
- Stock markets mostly fall after Fed-fueled rally
- Harris slams Trump for hypocrisy on abortion as US starts voting
- Academy to host first overseas ceremony to honor young filmmakers
- No doctor necessary: US okays nasal spray flu vaccine for self-use
- Gurbaz, birthday boy Rashid lead Afghanistan to 177-run rout of South Africa
- Former delivery man Baldwin leads star names at PGA Championship
- Trump shooting: Secret Service admits complacency
- Can an ambitious Milei make Argentina an AI giant?
- Haiti, its suffering growing, in 'race against time': UN expert
- Ibrahim Aqil, the Hezbollah elite unit commander wanted by the US
- Chinese forward Cui signs NBA contract with Brooklyn Nets
- US Fed dissenter calls for 'measured' pace of rate cuts
- Guardiola tells players to lead change over workload as Kompany demands cap on games
- Norway limits wild salmon fishing as stocks hit new lows
- Top Hezbollah commander killed in Israeli strike on Beirut
- Rotterdam fatal knife attacker suspected of 'terrorist motive'
- First early votes cast in knife-edge US presidential election
- Top-ranked Swiatek out of Beijing due to 'personal matters'
- Hard-right Reform UK looks to the future after vote success
- Embiid agrees to NBA contract extension with 76ers
- Joshua aims to complete road to redemption in Dubois bout
- World champion Bagnaia sets pace with lap record at Misano
- Biden says 'working' to get people back to homes on Israel-Lebanon border
- Pope criticises Argentina's crackdown on protesters
- Court limits screenings of videos in France mass rape case
- Gurbaz century takes Afghanistan to 311-4 in 2nd ODI
- Central banks face 'difficult balancing act': IMF chief
Super-resistant mosquitoes in Asia pose growing threat: study
Mosquitoes that transmit dengue and other viruses have evolved growing resistance to insecticides in parts of Asia, and novel ways to control them are desperately needed, new research warns.
Health authorities commonly fog mosquito-infested areas with clouds of insecticide, and resistance has long been a concern, but the scale of the problem was not well understood.
Japanese scientist Shinji Kasai and his team examined mosquitos from several countries in Asia as well as Ghana and found a series of mutations had made some virtually impervious to popular pyrethroid-based chemicals like permethrin.
"In Cambodia, more than 90 percent of Aedes aegypti mosquitoes have the combination of mutations that results in an extremely high level of resistance," Kasai told AFP.
He found some mosquito strains had 1,000-fold resistance, compared to the 100-fold seen previously.
That meant insecticide levels that would normally kill almost 100 percent of mosquitoes in a sample killed only around seven percent of the insects.
Even a dose 10 times stronger killed just 30 percent of the super-resistant mosquitoes.
"The resistance level that we found in mosquitos in Cambodia and Vietnam is totally different," said Kasai, director of the Department of Medical Entomology at Japan's National Institute of Infectious Diseases.
Dengue can cause hemorrhagic fever and infects an estimated 100 to 400 million people a year, although over 80 percent of cases are mild or asymptomatic, according to the World Health Organization.
Several dengue vaccines have been developed, and researchers have also used a bacteria that sterilises mosquitoes to tackle the virus.
But neither option is yet close to eradicating dengue, and Aedes aegypti mosquitoes carry other diseases, including zika and yellow fever.
- New formulas needed -
Resistance was also detected in another type of mosquito, Aedes albopictus, though at lower levels -- possibly because it tends to feed outdoors, often on animals, and may be exposed to insecticides less than its human-loving Aedes aegypti counterparts.
The research found several genetic changes were linked with resistance, including two that occur close to the part of mosquitoes targeted by pyrethroid and several other insecticides.
Resistance levels differed, with mosquitos from Ghana as well as parts of Indonesia and Taiwan still relatively susceptible to existing chemicals, particularly at higher doses.
But the research shows "commonly employed strategies may no longer be effective," said Cameron Webb, an associate professor and mosquito researcher at NSW Health Pathology and the University of Sydney.
"There is growing evidence that there may not be a place for current insecticide formulations in controlling populations of key mosquito pests," Webb told AFP.
He said new chemicals are needed, but authorities and researchers also need to think of other ways to protect communities, including vaccines.
"We have to think about rotating insecticides... that have different target sites," added Kasai, whose research was published last month in the journal Science Advances.
"The problem is that we don't have so many different kinds that we can use."
Other options include more efforts to remove breeding sites.
When and where the mutations for resistance emerged is still a mystery, but Kasai is now expanding the research elsewhere in Asia and examining more recent samples from Cambodia and Vietnam to see if anything has changed from the 2016-2019 study period.
"We are worried that the mosquitoes with the mutations that we found in this study will spread to the rest of the world in the near future," he said.
"Before that, we have to think of a solution."
A.Mahlangu--AMWN