For one thing, according to Meng, who is considered one of the world’s leading experts on swine viruses, the Centers for Disease Control in Atlanta and the World Health Organization in Geneva have spent the past several years creating management protocols designed to deal with a global pandemic that might be caused by Avian Influenza H5N1, or “Bird Flu.” Pharmaceuticals have been stockpiled, and outbreak management and risk communication plans have been developed to minimize transmission patterns and contain the scope of a potential outbreak.
“Mortality from flu is generally not considered very high considering the high number of people who are being infected every year,” said Meng, although he does believe that it could spread quickly since it appears to be a novel virus and human-to-human transmission is occurring. “But it does look like one of those bugs that has the potential of leading to a pandemic.”
Meng suggested that possible reasons for the increased mortality rate associated with the Mexican cases as opposed to the American cases could be attributed to differences in the sophistication of the two healthcare systems, it could be the result of “other co-infecting or underlying diseases” that remain unclear at this time or it could be due to the very small number of cases that have been currently diagnosed in the United States.
“We have much to learn about this specific virus,” said Meng, who has a medical doctorate and a Ph.D virologist who frequently works with the National Institutes of Health and other organizations on infectious disease research and containment programs. “But then again, we have much to learn about many other zoonotic disease viruses.”
From SARS to Bird Flu, most of the emerging diseases affecting people today come from pathogens most often associated with animals, according to Meng, who is among a growing legion of scientists trying to convince the federal government to invest more money in studying animal pathogens as part of an overall effort to protect humans from disease. According to a recent article published in Science, Meng said, only $32 million of the $88 billion U.S. Department of Agriculture 2007 budget was allocated for farm animal disease research.
“If we can understand more about these viruses, their transmission behavior, and the mechanism of cross-species infection among animal and human populations, then we can better prepare ourselves for protecting human populations,” said Meng, who recently participated in a National Institutes of Health sponsored expert workshop entitled “Cross Species Infection Workshop” in Washington D.C. that summarized the dangers and called for the need to study the animal viruses in animals such as pigs before they jump species and infect humans.
“It will likely be several days before the virus is fully characterized in the laboratory,” he said. “Once that work is finished, we’ll know a lot more about how to proceed with the management of this situation.”
Meng said that one of the major factors that might minimize the scope of the outbreak and the spread of the virus could be related to the timing of this outbreak. Influenza viruses are “envelope viruses” that can be more efficiently transmitted in cold winter conditions that facilitate the survival of the virus, Meng said, and they typically do not do well in hot summer temperatures. “That is something that may limit the spread of this new virus,” he said.
The strain of swine virus H1N1 responsible for the emerging epidemic does not normally infect people and there are only a few cases of swine flu infections in humans each year in the United States, according to Meng. Because pigs have receptors for human, avian and pig viruses, they serve as a “mixing vessel” for new viruses, he said. This particular strain is believed to include components from pig, bird and human viruses that have been combined through a process known as genetic re-assortment. Humans are likely immunologically naïve to the new virus that has been created, which is why the danger for a potential global pandemic does exist.
