Predicting illness is like weather forecasts. Although we cannot predict specific outbreaks or specific storm details, we can well identify these threats as they are emerging and prepare accordingly.
Viruses that cause avian flu are a potential threat to global health. Recent animal outbreaks The subtype called H5N1 is particularly troublesome for scientists.
Human infections from H5N1 were relatively rare, but Over 900 known cases worldwide Since 2003 – Almost 50% of these cases are fatal – About mortality rate 20x More than the 1918 flu pandemic. If the worst of these rare infectious diseases have become commonplace so far, the outcome can be catastrophic.
My colleague approaches the threat of a potential disease from anthropological perspective. And me Recently published booksNew infectious diseases: Three epidemiological transitions from prehistoric to present‘Investigate How human behavior was shaped The evolution of infectious diseases began with the first major emergence of the Neolithic period and has continued for 10,000 years to date.
From this deep time perspective, it becomes clear that H5N1 displays a common pattern Gradual intrusion From animals to human populations. Like many emerging viruses, H5N1 is undergoing progressive evolutionary changes that allow it to be transmitted between people.
The period between these evolutionary steps presents an opportunity to slow this process and perhaps avoid global disasters.
Spillover and virus chatter
If disease-causing pathogens such as influenza viruses are already adapted to infect certain animal species, their ability to infect new species, such as humans, may ultimately evolve. A process called Spilover.
Spilover is a tricky company. Pathogens need the correct set to succeed Molecule “key” It is compatible with host molecule “locks” so that it can enter and exit host cells and hijack replication machines.
These locks often differ between species, so pathogens may need to try many different keys before infecting an entirely new host species.
For example, a virus can successfully use chickens and ducks that do not work on cows or humans. And, new keys can only be created through random mutations, so the probability of getting all the right mutations is very slim.
Given these evolutionary challenges, pathogens are not surprising Often stuck Breasts in the spillover process. New variants of pathogens may be able to be transmitted from animals to either person only More susceptible Because of pre-existing diseases or because of spread exposure to pathogens, they are more likely to be infected.
Still, the pathogen may not be able to escape from its human host and communicate it to others. This is the current situation for H5N1.
It’s been there for the past year Many animal outbreaks Especially among birds and cattle, in a variety of wildlife and livestock. However, there were also a small number of human cases, but most of them occurred. Poultry and Dairy Workers People who worked closely with many infected animals.
Epidemiologists call this situation Virus chatter: Human infections are small bursts of unclear information that can lead to very ominous messages when only occur in small sporadic occurrences that appear to be chatty signals of encoded wireless communications. In the case of viral chat, the message becomes a human pandemic.
Sporadic, individual cases of H5N1 among people suggest that Propagation from humans to humans It could happen at some point. But even so, no one knows how long it will take for this to happen, or how many steps it will take.
The flu virus evolves rapidly. This is because two or more flu varieties can infect the same host at the same time, allowing them to do so. Convert their genetic material into each other Producing a completely new variety.
These reconstruction events are more likely to occur in the presence of a diverse range of host species. Therefore, it is particularly concerning that H5N1 is known to be infected At least 450 animal species. It may not be long before virus chatter will give way to the bigger human epidemic.
Reshape the trajectory
The good news is that people can take basic steps to slow the evolution of H5N1, and if it becomes a common human infection, it can potentially reduce the fatality of avian influenza. But governments and businesses need to act.
People can start by caring for food animals better. Total weight of poultry in the world It is larger than all wild bird species combined. So most geography H5N1 Outbreak It tracks more closely with the international relocation of large housing and live poultry than nesting and moving patterns of wild aquatic birds.
Reducing these agricultural practices could help to suppress the evolution and spread of H5N1.
People can also take better care of themselves. At an individual level, most people can get vaccinated Common seasonal influenza virus It spreads every year.
At first glance, this practice may not appear to be related to the appearance of influenza in birds. However, in addition to preventing seasonal diseases, vaccinations against common human varieties of the virus reduce the likelihood of mixing with bird varieties and provide the properties necessary for human-to-human transmission.
At the population level, society can cooperate Improve nutrition and hygiene With the poorest people in the world. History shows that improving nutrition increases overall resistance to new infectious diseases, and better hygiene reduces the frequency and frequency of exposure of people to new pathogens. And in today’s interconnected world, the problem of disease in all society It will eventually expand For all society.
For over 10,000 years, human behavior has shaped the evolutionary trajectory of infectious diseases. Knowing this, people can better reconstruct these trajectories.
Ron BarrettProfessor of Anthropology, McAlester College
This article has been republished conversation Under the Creative Commons license. Please read Original article.
