Texas officials today issued a “health alert” about the first confirmed case of a human infection with a bird influenza virus that has found its ways into dairy cows in the US. The worker developed conjunctivitis, a mild eye infection that frequently occurs when avian influenza viruses jump into humans. www.science.org/content/article/us-dairy-farm-worker-infected-as-bird-flu-spreads-to-cows-in-five-states?
The case is the latest surprise in the global march of the flu strain, a subtype of H5N1 known as clade 2.3.4.4b that has devastated wild birds and poultry around the world for more than 2 years. The U.S. Department of Agriculture (USDA) says it has confirmed the virus has infected cattle at farms in Texas, Kansas, New Mexico, and Michigan, while Idaho has a “presumptive” outbreak at one dairy farm. Wild birds, which have been found dead on some farms, most likely contaminated cow feed or water.
Some evidence suggests the virus was transmitted between cows, but that remains unproven. And for now, USDA says its “initial testing has not found changes to the virus that would make it more transmissible to humans.” Still, the widespread occurrence of H5N1 in mammals has renewed worries that it may evolve to become more transmissible between people. And scientists are urgently trying to answer a host of questions, including how far the virus has spread among U.S. cows and how to prevent more herds and people from becoming infected.
Although cows routinely contract influenza viruses, this is the first time that a “highly pathogenic” bird flu strain has been found in them. USDA says about 10% of affected herds have become ill. Sick cows have a mild illness, and produce less milk, which is thicker than usual, resembling colostrum, the first milk produced after a calf is born.
USDA today stressed that the “current risk to the public remains low.” Contamination of commercial milk is of “no concern,” the agency said in a statement, because pasteurization reliably kills viruses, and milk from sick cows is not being sold. The U.S. Centers for Disease Control and Prevention (CDC) says people should not drink raw milk or eat products such as cheese that are made from it. The USDA statement noted that cats on farms have also become infected.
Antibody tests of herds should soon reveal how widespread the infection is and how long it has been infecting cattle. Lab experiments may clarify how a virus that typically causes respiratory disease wound up in cow udders, making it detectable in their milk, and whether other organs are infected. No evidence exists that the virus has infected beef cattle, but researchers say that could simply be because of a lack of surveillance, or because these animals show subtler symptoms than changes in milk production and its appearance.
A major question now looming is how to prevent further spread from dairy farms. Most countries, including the U.S., require culling of entire poultry flocks if even a single bird is infected with a highly pathogenic avian influenza virus. But there is no talk of culling cows, which cost up to $2500 each and are not becoming seriously ill.
There are no H5N1 vaccines for cattle. Poultry vaccines do exist and are used heavily in China, with some marked successes. A crash program to develop a cattle equivalent might make sense, says Carol Cardona, an avian influenza specialist and poultry veterinarian at UM Twin Cities. If vaccinations can reduce viral spread, they might offer some secondary protection to dairy workers. “The person-to-cow ratio is so much higher than the person-to-chicken ratio,” notes Cardona, putting many more workers at risk. The cattle infections are “a game changer,” she adds. “I think it’s all hands on deck.”
David Swayne, who formerly ran USDA’s avian influenza research lab, says it would be possible to quickly make a new cattle vaccine by modifying one now used in swine. And unlike the bird vaccines, which are banned in the U.S. due in part to international trade concerns, swine vaccination is already “widely accepted,” Swayne says.
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The advent of antibiotics ushered in a new era of medicine in which previously life-threatening infections became minor concerns easily solved with a few pills. Unfortunately, those pills have become increasingly ineffective as bacteria evolved resistance to the major classes of antibiotics. Scientists have struggled to come up with new antibiotics to thwart these multidrug-resistant microbes. But part of the solution might be right in front of them: All sorts of drugs not designed to battle bacteria can act as antibiotics, a study finds.
Researchers tested thousands of nonantibiotic drugs for their ability to kill E. coli bacteria. While most did nothing, nearly 200 exhibited antibacterial activity against the microbes. These included drugs for psychiatric conditions and diabetes, which appear to kill microbes in totally different ways from current antibiotics.
That means these drugs could help researchers develop new classes of antibiotics, the team writes. Intriguingly, though, they found that microbes that evolved resistance to these nonantibiotic drugs were often able to shrug off classic antibiotics, too. Further investigation pointed to a molecular pathway shared by microbes resistant to antibiotics and bacteria-killing nonantibiotics alike—a target that could undermine all sorts of antibiotic resistance and make so-called superbugs vulnerable again if researchers can figure out how to hit it.
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Pfizer’s antiviral Paxlovid (nirmatrelvir/ritonavir) may not help as many people as hoped. The combo drug was granted emergency use authorization in 2021 in the United States after a clinical trial showed it reduced hospitalizations and deaths among people who were unvaccinated against SARS-CoV-2 and had at least one risk factor for severe COVID-19, such as diabetes or obesity. But results from a Pfizer-run trial of nearly 1300 people suggest the benefit doesn’t extend to those who are unvaccinated and have no risk factors or are vaccinated with at least one. https://www.science.org/content/article/news-glance-giant-telescope-camera-complete-limits-paxlovid-benefits-and-missing?
The study, out this week in The New England Journal of Medicine, found that in these groups, Paxlovid was no better than placebo at preventing deaths and hospitalizations, or at reducing time to symptom clearance. The findings support the use of the drug “only for persons who are at high risk for disease progression,” write infectious disease specialists Rajesh Gandhi and Martin Hirsch, both of Harvard Medical School and Massachusetts General Hospital, in an accompanying commentary
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The protein-making technology behind some of the most successful COVID-19 vaccines is showing hints of success in people with a rare metabolic disease. www.science.org/content/article/news-glance-giant-telescope-camera-complete-limits-paxlovid-benefits-and-missing?
Results from a small trial run by Moderna, out this week in Nature, are the first published clinical data showing that messenger RNA (mRNA), used in vaccines to deliver viral proteins that provoke an immune response, could potentially work as a drug to replace a missing protein. The trial included 16 children and young adults born with mutations that cause propionic acidemia, in which cells lack an enzyme that enables them to break down certain proteins and fats. Even with a special diet, toxic compounds build up and can cause strokes, heart disease, and other problems. Trial participants got up to 2 years of intravenous infusions, usually 2 weeks apart, of tiny fat particles containing mRNA encoding normal forms of the missing enzyme. Among eight participants who had at least one life-threatening medical emergency in the year before treatment, such episodes fell by 70%.
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Member states of the World Health Organization (WHO) failed to hammer out a sweeping treaty to address global pandemic preparedness during what was supposed to be a final round of talks last week in Geneva. WHO launched negotiations about the Pandemic Agreement in December 2021 with the aim of addressing problems identified during the COVID-19 pandemic, including a searing global inequity in the distribution of vaccines. But sharp divisions have emerged between member states, in particular about a system called “pathogen access and benefits-sharing,” which would kick in during a pandemic. It would compel countries to provide the world with information about microbes within their borders in return for access to free or affordable vaccines, drugs, and diagnostics. Negotiators will hold another 11-day meeting starting on 29 April, in hopes of agreeing on a draft before the World Health Assembly in late May.
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A diabetes drug called lixisenatide has shown promise in slowing the progression of Parkinson’s disease. Lixisenatide is in the family of GLP-1 receptor agonists, such as Ozempic, that have made headlines as weight-loss drugs. In the latest clinical trial, lixisenatide was given to people with mild to moderate Parkinson’s who were already receiving a standard treatment for the condition. After a year they saw no worsening of their symptoms, unlike a control group whose condition did worsen. Further work is needed to reduce the drug’s side effects, such as nausea and vomiting, and to determine whether its benefits last. “We’re all cautious. There’s a long history of trying different things in Parkinson’s that ultimately didn’t work,” says neurologist David Standaert.
Nature | 4 min read
Reference: The New England Journal of Medicine paper
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Researchers have identified gut bacteria that can transform artery-clogging cholesterol into a more harmless form. In previous work, the authors showed that a bacterial enzyme called ismA can metabolize cholesterol into coprostanol, a lipid that is excreted instead of absorbed by the body. They have now identified gut bacteria, including several Oscillibacter species, that correlate with lower cholesterol levels in people. These species could also metabolize cholesterol in lab experiments. Whether these bacteria can directly influence blood cholesterol in people needs to be confirmed, but if they could be delivered to the right place in the gut, it might lead to new treatments.
Nature | 4 min read
Reference: Cell paper
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Lalita Panicker is Consulting Editor, Views and Editor, Insight, Hindustan Times, New Delhi
