Egyptian health officials have just reported two deaths from bird flu within days of each other. The dangerous virus variant H5N1 struck down a six-year-old boy and a young woman, bringing the total death toll in Egypt to 25. While bird flu experts note that Egypt has seen a surge in human cases in recent months, with 16 confirmed since the start of the year, compared to seven cases between January 1 and April 17 last year [Reuters], they also say that the Egyptian people’s level of alarm is out of proportion to the threat.
Rumors have appeared in the Egyptian media that the virus is circulating widely, and that some people get “silent infections” which show no symptoms, but still allow them to pass on the virus. The rumors have been fueled by the pattern of recent infections: Many of the infected patients have been toddlers, leading to the belief that stronger adults are also infected but simply show no symptoms. Although thousands of Egyptians have rushed their children to hospitals this flu season, there is no evidence yet of asymptomatic avian flu cases or any significant mutation in the H5N1 virus. “Right now, it’s all hot air,” said Dr. Robert G. Webster, a flu expert…. “I hope to hell it’s not happening, because it would mean the virus is adapting to humans. But there’s not a shred of data” [The New York Times].
While the H5N1 virus rarely infects people, the looming fear is that the virus may mutate into a form that can be transmitted easily from person to person, which could spark a deadly pandemic. However, an outbreak of swine flu across the world from Egypt, in Southern California, has reminded people of the hazards of overreacting before all the information is in.
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Flu season is taking a toll on chicken farms across Asia, where new bird flu outbreaks are cropping up from China to India, leading to massive poultry slaughters. Health officials say the chickens are infected with the deadly bird flu strain known as H5N1, but thus far there have been only a few cases of human infection. Two human cases have been reported in Indonesia, one in Cambodia, and in Egypt a 16-year-old girl died of the virus. Yi Guan, a Hong Kong microbiology professor, says the recent spate of cases across the region may not be completely isolated and would likely get worse as winter sets in, when the risks of influenza tend to peak [The Wall Street Journal].
In China, more than 370,000 chickens were culled after an outbreak was announced in the eastern province of Jiangsu. The usual precautions have been imposed: birds have been slaughtered in the surrounding area, farms quarantined and disinfected, and the transport of fowl banned. But no information has been released about the scale of the outbreak – how many birds were found to be carrying the H5N1 strain of the virus and how many of them died [BBC News]. Chinese authorities say migrating birds probably brought the virus to local farms.
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The chicken industry has been remarkably effective in breeding efficient egg-layers and plump-breasted broilers, but a new study says that focus has created a chicken population that lacks genetic diversity, leaving the birds more vulnerable to diseases. The study found that industrial chickens have lost about half of the genetic variations once found in the wild chicken populations, and some have lost 90 percent of those genes.
This means most of the world’s chickens lack characteristics that evolved when they lived in the wild, and may be useful again to help them face stress and disease as livestock. Scientists want to breed DNA for traits such as disease resistance, or “animal well-being”, back into commercial birds without introducing undesirable traits at the same time [New Scientist]. Researchers say the biggest concern is that if commerical chickens are nearly identical genetically they’ll all be susceptible to the same infectious diseases, and an outbreak of of a ailment like avian flu could devastate the entire industry.
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A warmer world will also be a sicklier place for both animals and humans, according to a new report from the Wildlife Conservation Society (WCS). Dubbed the “deadly dozen,” sicknesses such as Lyme disease, yellow fever, plague, and avian influenza, or bird flu, may skyrocket as global shifts in temperature and precipitation transform ecosystems. Babesia, cholera, Ebola, intestinal and external parasites, red tides, Rift Valley fever, sleeping sickness and tuberculosis round out the list [National Geographic News].
The report spells out how global warming is changing the ranges and habitats of animals that carry these infectious diseases, bringing the ticks that transmit Lyme disease and the mosquitoes that carry yellow fever and Rift Valley fever into contact with new human populations. “We’ve seen Lyme disease work its way up from the US into Canada, and West Nile fever as well,” said William Karesh, director of WCS’s global health programmes. “Basically what you have now are fewer frozen nights in this region, and that allows the ticks and mosquitoes that carry these diseases to survive further north” [BBC News].
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People who lived through the 1918 flu pandemic still have antibodies in their immune systems that can recognize and fight that flu virus, although the haven’t been exposed to it for 90 years. Such long-lived immunity was thought to be impossible without periodic exposure to the microbe that stimulated the immune system in the first place [Science News]. Researchers say these antibodies could be helpful in developing treatments for viruses similar to the deadly one that swept around the world in 1918, killing an estimated 50 million people.
For the study, which will be published in this week’s issue of Nature [subscription required], lead researcher James Crowe’s team studied antibodies in the blood of 32 people in their 90s and 100s, born during or before 1915. They found that all 32 people had antibodies to the 1918 strain of flu virus [HealthDay News]. In lab tests, the antibodies mounted a powerfully effective attack against a modern version of the virus. “This is entirely counter to everyone’s intuition — that elderly people would have such potent antibodies,” Crowe says. Aging typically reduces a person’s ability to build antibodies and develop immunity to diseases [Science News].
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When researchers speak in ominous tones about the possibility of a pandemic of avian influenza, commonly known as bird flu, they’re usually talking about the virus strain known as H5N1, which has killed 243 of the 385 people it has infected since 2003. But according to a new study, a relatively ignored strain known as H9N2 could easily mutate into a form that spreads freely among humans.
Luckily, researchers say that even if the H9 virus does acquire the ability to spread in people, at first the infection is likely to cause minor illness. “You’re going to have a bunch of people who don’t feel very well, as opposed to dropping off the face of the Earth,” says Raymond Pickles, a cell biologist…. But the new data indicate that if the H9 viruses mix with other human viruses, as commonly happens in nature, it could become more potent [Science News].
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Bird flu — or avian influenza, to give it its proper name — is the kind of lurking threat that keeps public health officials awake at night. Luckily, it’s still in the “lurking” column, because the often-deadly disease is not easily contracted by humans, and as far as doctors can tell, it can’t yet be transmitted from person to person.
But because the real threat is that the bird flu virus will mutate into a form that’s better at preying on humans, researchers keep a sharp eye on each flare-up, whether it’s an outbreak that annihilates a hen house or a cluster of human cases. In the past few days, researchers have encountered a bit of both.
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