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Polio’s last strongholds continue to cause issue; The latest health stories from around the world

The Global Polio Eradication Initiative (GPEI) has been struggling in Africa with large outbreaks spawned by the polio vaccine itself, which is made of live but weakened poliovirus. But the program at least had the wild virus on the run, driving down the cases it causes in its last strongholds, Pakistan and Afghanistan. Now, GPEI is facing a devastating setback on that front, too. 

In 2021 and 2022, through intensive vaccination campaigns, GPEI pulled off what its independent monitoring board (IMB) called a “remarkable achievement.” It cleared the wild virus from the teeming megacity of Karachi, Pakistan, which has long been a source of reinfection for the rest of the country. For more than 2 years, Karachi saw no paralytic polio cases, and extensive surveillance of wastewater turned up no sign of the wild virus. 

The virus also disappeared from Pakistan’s two additional historic “reservoirs”: areas around Quetta in the southwestern province of Balochistan, and Peshawar in the northern province of Khyber Pakhtunkhwa (KP), both near the long, porous border with Afghanistan. The virus was cornered in just seven districts of southern KP and a few in the East region of northern Afghanistan—the smallest geographic area in the history of the eradication program, according to a GPEI advisory group. 

But now, wastewater samples reveal the virus is back in Karachi and around Quetta and Peshawar, likely brought by people from those holdout districts. As of early June, the virus had spread to about 40 districts in Pakistan. It had also returned to Kandahar in the Southern region of Afghanistan. The number of paralytic polio cases remains relatively low because much of the population has been immunized—so far this year there have been five in each country. But plenty of virus is circulating, ready to strike any unvaccinated or under-vaccinated child. GPEI’s already-delayed goal of stopping all transmission of the wild virus this year is looking increasingly elusive. 

The current epidemiology is “alarming,” says Natalia Molodecky, who worked with GPEI in Pakistan’s polio emergency operations centre in Islamabad and is now a consultant for the Task Force for Global Health in Atlanta. “We are seeing continuous detections [of the wild virus] in Karachi, and we are seeing a lot more transmission across the country.” 

The first signs of trouble came in August and September 2023, when a couple of wastewater samples in the historic reservoirs tested positive for the virus. Over the past 4 months, it has really taken off, says GPEI’s Hamid Jafari, who directs the eradication program in the Eastern Mediterranean region, which includes Afghanistan and Pakistan. In just 1 week in May, the wild virus was detected in 26 environmental samples in Pakistan, and that was before the high season for its transmission began this summer. 

“The picture looks horrific,” Jafari concedes, “but actually the situation is not so bad.” For one, there are now more environmental surveillance sites in Pakistan than ever before, which explains some of the uptick, he says. Just two genetic clusters or lineages of the wild poliovirus are now circulating in the two countries, down from 12 in 2020—often a sign the virus is on the way out, Jafari says. The lineage endemic to Pakistan, known as YB3C, has not been spotted since November 2023. 

The virus now spreading across Pakistan originated in Afghanistan and travelled out of the border area with the hundreds of thousands, if not millions, of people, constantly on the move, Jafari says. The recent surge, for example, coincided with the Pakistani government’s “repatriation” of about half a million Afghan refugees. Stopping virus transmission will mean targeting this “moving reservoir,” who are repeatedly missed during standard door-to-door vaccination campaigns, he adds.  

Karachi contains all the conditions the virus needs to thrive: very high population density and constant movement—nearly 1 million people move in or out of the city every day, Molodecky says—along with poor sanitation and hygiene. Many children are infected with multiple pathogens, which lowers vaccine efficacy. Karachi also harbours pockets of strong resistance to polio vaccination. Polio workers, often from the same community, sometimes agree to fake finger marking—a sign a child has been vaccinated—or fail to report so-called “refusals,” Jafari says. 

Michael Galway, who leads the Bill & Melinda Gates Foundation’s eradication efforts in Afghanistan and Pakistan, says, “It will be a heavy lift to clear out the virus from all of these historic reservoirs, but the proof of concept is there. We have done it before.” Southern KP is “a different reality,” he says. There, the insecurity, tribal conflict, and community boycotts make it almost impossible for the polio program to operate. An estimated 300,000 children have been consistently missed in vaccination activities there and in the Eastern region of Afghanistan, according to the IMB. Nor is the true extent of ongoing transmission there known. In these rural areas there are no sewage systems, so environmental surveillance sites are few. 

Some think that with redoubled efforts, GPEI can still stop wild poliovirus transmission this year. Galway and Jafari are less optimistic. Jafari says that if the program can confirm what’s driving the circulation of wild virus and find innovative ways to reach missed children in the newly reinfected areas and in the entrenched border area, “then we have a strong chance to stop transmission during the next low season. I think it will take until mid-2025.” 


Scientists have long been puzzled by the fact that women tend to live longer than men. Social and behavioural factors only partially explain this trend, especially given that it’s not just us: The “longevity gap” shows up all across the animal kingdom. Now, new experiments in fish have revealed that germ cells, which give rise to sperm and eggs, affect male and female lifespans in totally opposite ways—they are likely major drivers of differences in lifespan.
Turquoise killifish only live a few months, yet still, females have longer lifespans than males. When scientists genetically engineered the fish to lack germ cells, however, that gap vanished: Males lived longer—and females died much earlier—than expected. Further experiments determined that removing egg cells reduced oestrogen levels in female killifish, potentially increasing their risk of cardiovascular disease. These eggless females also produced more of a protein called IGF-1, which made them grow larger while also suppressing other signals that maintain health and slow aging.
Male killifish without sperm, meanwhile, practically glowed with health. Their skin, muscles, and bones all appeared unusually youthful, and their bodies had increased amounts of active vitamin D—suggesting that the nutrient plays a role in longevity. Sure enough, when researchers treated killifish with a vitamin D supplement, they were able to significantly extend the lifespans of both male and female fish. The same substance, they say, may play a similar role in other animals—though extending life expectancy in humans will take more than simply popping a pill every day. Further research on how making eggs and sperm affects the body may reveal other ways of helping people live longer, healthier lives.  


The antiviral drug combination Paxlovid is safe but ineffective against Long Covid, according to the first randomized, controlled trial of the medication, published in JAMA Internal Medicine last week. 

The Stanford University trial, in which 155 people got a 15-day course of either Paxlovid or a placebo, was stopped early when the drug failed to significantly improve fatigue, brain fog, body aches, shortness of breath, and cardiovascular or gastrointestinal symptoms. The results don’t invalidate the hypothesis that Long Covid is caused by the SARS-CoV-2 virus persisting in the body, the study authors argue. They call for studies that test longer treatment durations, target different symptoms, or combine antivirals with other therapies. Several other antiviral trials are due to report results over the next 2 years. 


A team of geneticists and archaeologists has uncovered the first direct evidence that ancient people spread malaria long before the advent of air travel and automobiles. Researchers combed through more than 10,000 ancient human genomes, looking for DNA from malaria-causing Plasmodium parasites. 

The team re-sequenced likely samples, it reports last week in Nature, and identified 36 cases of malaria from around the world, from a man who died in Stone Age Germany 5600 years ago to soldiers buried in Belgium in the early 1700s. The earliest case in the Americas came from a Peruvian site dating to about 1600 C.E., suggesting the disease was introduced to the New World by European colonists. Until now, the oldest direct evidence of malaria came from a 1944 blood sample from Spain. 


Countless external factors influence human health and wellbeing. Environmental pollutants, pathogens, access to healthcare, income, chemical toxins, neighbourhood walkability, and more all affect our quality of life. However, it’s difficult to pinpoint how all these physical, environmental and social factors—collectively known as the exposome—lead to poor health outcomes in the short-term, like asthma, or in the long-term, like cancer or respiratory disease. Now, in a Science Perspective, some experts suggest our furry best friends can help us better understand how our world affects our health.
Pets—specifically dogs—share physical and social environments with their owners. We expose them to everything we come into contact with—from pesticides and ticks in our front yards to chemicals in our skincare and cleaning supplies. “They’re sniffing a lot, they’re licking a lot,” study author Courtney Sexton told Science’s Sarah Crespi in an accompanying podcast. “External factors that influence our biology are going to be really noticeable when they impact dogs.”
As the veterinary industry moves to standardise data collection for their canine patients, a group of scientists is advocating for a new protocol: collect basic demographic and geographic data on dog owners as well. The pets’ intimate proximity to humans combined with their shorter lifespans make them good sentinels of human health, so we “don’t have to wait 70, 80 years to see what the [health] outcomes are,” said Sexton. With more data on pets and pet owners, we can better understand and potentially modify our shared exposome to improve our collective quality of life. 


Lalita Panicker is Consulting Editor, Views and Editor, Insight, Hindustan Times, New Delhi

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