New study shows the power of invasive Asian mosquitoes to ‘change the landscape’ of malaria in Africa

A new study has linked an invasive, insecticide-resistant mosquito native to South Asia to an unprecedented urban outbreak of malaria in Ethiopia. Africa, which previously had low rates of disease.

The report, released today at the annual meeting of the American Society for Tropical Medicine and Hygiene (ASTMH), follows dubious reports of a 40-fold increase in the number of cases. malaria New evidence suggests that this mosquito, which was not identified in Africa until 2012, poses a significant threat to the goal of eradicating malaria from the continent.

“African malaria is usually associated with the rainy season. rural areabut this mosquito spiked malaria infections 10-fold in just three weeks urban area Between dry seasonsaid Dr. Fissam G. Tadesse, a molecular biologist at the Almauer Hansen Institute in Addis Ababa. In man-made reservoirs such as those found in rapidly expanding urban areas. ”

The outbreak occurred in Dire Dawa, a city of about 500,000 people in eastern Ethiopia, where only about 200 cases are normally recorded per year. However, around 2,400 cases were reported between January and May 2022, when there was little rain and infections were particularly rare. Research by Tadesse and his colleagues found that the surge was caused by a mosquito known as the Anopheles mosquito. They also found that mosquitoes are resistant to the insecticides most commonly used to control malaria through treated bed nets and indoor insecticide spraying.

Most malaria in Africa is caused by a mosquito species known as Anopheles gambiae. The population rises and falls with the rainy season, which swells the local waterways. Anopheles mosquitoes have long been a major vector of malaria in urban areas of India and Iran. However, it was not seen in Africa until 2012 when it was reported from Djibouti. Djibouti, at the time, was a small country of about one million people that was close to eradicating the disease. Ann.Stephensi Mosquitoes May Have Arrived shipping containerTadesse said, but they weren’t seen as a significant threat until 2020 when they were suspected as the cause of Djibouti’s steadily increasing malaria infections since 2013.

Now there is new evidence that they were the source of the Dire Dawa outbreak, combined with recent evidence from Ann. There are growing concerns that a new front is opening up in the ongoing battle against malaria. Africa suffers from her 95% of the world’s 627,000 annual malaria deaths, most of which are children under the age of five. In recent years, progress against this disease has stagnated.

“This is unlike any other malaria-carrying mosquito we’ve seen in Africa so far,” said disease ecologist and Anne’s Dr Sarah Zordi. A key partner in Ethiopian research, the US President Malaria He is working with the Initiative (PMI), she stephensi expert at the US Centers for Disease Control and Prevention (CDC). “The ability of this mosquito to persist in dry seasons and urban environments could change the malaria landscape in Africa,” she said.

“It is likely that malaria will spread from a predominantly rural disease to both rural and urban challenges, affecting rapidly growing and densely populated cities in Africa, where infection rates are relatively low. will give you.”

Meanwhile, another study presented at the ASTMH Annual Meeting found that An. stephensi mosquitoes are ubiquitous in and around homes in nine states of Sudan. Zohdy raised concerns about detecting An. Stefensi mosquitoes in Sudan and Nigeria were able to follow the Djibouti pattern.

Zohdy said the CDC and PMI, which are jointly conducted by USAID and CDC, are actively working to mitigate the An threat. By utilizing enhanced vectors and disease surveillance, Stefensi. PMI and CDC are also working with the World Health Organization, which launched an initiative last month to stop the spread of An. African Stephensi. In addition, PMI is leading the deployment of An-informed interventions. The unique biology of Steffensi, including the development of methods to limit urban breeding grounds.

What Ethiopia’s Outbreak Tells Us About Africa’s Emerging Malaria Threat

Following the outbreak in neighboring Djibouti, Ethiopia’s malaria experts were warned of the potential threat from Ann, Tadesse said. Stephensi mosquito. He said Dire Dawa is a rail hub leading to Djibouti. When malaria infections suddenly spiked earlier this year, he and his colleagues “immediately started thinking ‘Stephensi’,” he said, adding, “We jumped in to assess the cause of the change.” Motivated, a team including Tadele Emiru and Dr. Deiene Getachew completed the field survey in just over two months.

In addition to linking Anne. From stephensi to malaria infections, Tadesse and his colleagues conducted extensive testing in homes and nearby water sources where cases occurred. They found evidence of An carrying malaria. Confirming what is already known from extensive studies in India, An. stephensi is primarily known as the ‘container breeder’. But he said he found a lot of Ann too. Stephensi mosquitoes at the edges of streams and nearby rivers.

“Be wary of looking at it as just a container breeder,” Tadesse said. “It can survive in artificial or natural water sources. It can also feed on animals and humans. Basically, our findings show that it can survive anywhere.” So we’ll have to look for these mosquitoes in previously unpopulated areas and hopefully find them.”

For example, he made the following predictions: 126 million people added Africa may be at risk of malaria from Ann. If the evidence from Dire Dawa on mosquito adaptability is confirmed elsewhere, the stephensi mosquito may underestimate the threat.

Daniel Bausch, MD, MPH&TM, FASTMH President, ASTMH said: “Strong surveillance to detect and investigate unusual outbreaks in African countries will help develop strategies to prevent this invasive mosquito from derailing Africa’s efforts to eradicate malaria. It’s essential.”

Courtesy of the American Society of Tropical Medicine and Hygiene