Pigs Could Be A Place Where Avian Flu Could Mutate to Harm Humans: Why is there nothing in the news about this fact and that H5N1 has hit some pigs?

With all the discussion of avian flu i thought I'd write a post today on how and why pigs could be a way that this virus would become much more easily transmitted to humans. So i googled for pigs and avian flu. What came up was scary. I would have thought that the presence of avian flu in pigs would have been well reported considering how dangerous it is. I was wrong. There has already been transmission of the H5N1 virus to pigs, why it has not been extensively covered is beyond me. Maybe the reporters aren't putting the science together.

We are well overdue for a pandemic bird flu or not.. Closing borders won't help with the ease of travel these days. The next flu pandemic may have nothing to do with the current avian flu or it may have everything to do with it. It seems to me however that we should be kept abreast of this type of information, which only seems to be in the news here and there and which isn't being given much attention. When we had the local bird flu outbreak in BC last year (which was not the H5N1 strain) was there any discussion about making sure that pigs did not get near the farms? I didn't see any and for the large farms it's quite possible they only had chickens. But it wasn't only large farms that were affected. In the end they stopped the outbreak partially by limiting travel between farms, as it seemed it was being passed on by dirt most likely in people's shoes. It seems to me that this is an important precaution to take and one that was never even mentioned in Canada although i am seeing it slowly being mentioned in the international press.

First off small family farms are likely to have more visitors, thus spreading of the avian flue (of whatever kind become more likely). And it is generally small farms in Asia where the H5N1 of avian flu is occurring. But that compares (IMO) to the danger of having swine in the generally vincinity of birds especially in smaller farms. But where else would one find pigs and birds together. Most likely in small farms. I don't know exactly how to solve that problem. What scares me is that it is scarcely being discussed in "first world" countries. And how much accuracy can we count on from China where the outbreaks have showed the links to pigs.

I'm including broader quotes in this article especially on the science stories as this isn't a science blog it's a political blog. If the quotes seem to long or you already know a fair bit about it just skip the material.

The Guardian has a story of the fear that the avian flu will transfer to pigs.

In Scientists fear pigs may play role in bird flu:
James Meikle, health correspondent

Wednesday August 24, 2005
The Guardian

Powers to cull and control poultry as well as remove potentially infected birds from the food chain are already available but it emerged yesterday that talks are under way on whether further measures might be necessary.

Scientists fear that pigs can act as "mixing vessels" for flus that would otherwise be mainly harmful to birds - although humans in close contact can be infected and killed by such viruses - and turn them into a highly contagious disease that spreads easily between humans....

....There was no clear indication of how many farms have pigs and poultry on them [in the UK], especially since the law did not require poultry owners to be registered. "I suspect the number that have a few poultry running round the place is probably quite significant." About 30%-35% of the pig breeding herd was now thought be outdoors, he said.

China confirms bird flu in pigs

Chickens in cage
Scientists fear more humans could be infected in the future
China has confirmed reports that the deadly H5N1 strain of bird flu has been found in its pig population.
Thursday, 26 August, 2004

Jia Youling, director general of the Ministry of Agriculture's veterinary bureau, told a Beijing news conference that the two infected pigs had been found in the same area of China. But he declined to say where, citing the need to protect the interests of the local population....
...."The H5N1 virus infecting pigs is a chance, individual occurrence. There is no evidence yet the H5N1 bird flu virus can be passed from pig to pig, or of pigs infecting people," Mr Jia told Reuters news agency.

Other stories that i came across that linked the H5N1 strain of bird influenza to pigs include Bird flu in pigs no epidemic: officialsWednesday, Aug 25, 2004 and notes DANGEROUS: A Chinese health official called the discovery of the deadly H5N1 flu strain in pigs a dangerous sign, but played down the possibility that is might spread, Indonesia Finds Bird Flu in PigsSaturday, 14 May 2005,Inevitable that H5N1 avian influenza viruses will be detected in pigsThursday, 26-Aug-2004.

Now these articles tend to be from a specific time period mostly in 2004 although there are some from 2005. Very bare coverage of the topic. The articles here are just a selection of the articles that i did find. If you want to find out more about avian flu in pigs it's easy to google up.

There are strong reasons for why this should be getting more coverage.

Pigs are close to humans in many ways. Close enough that there has been discussion about organ transplants from pigs to humans. Close enough that once pigs insulin was used for diabetics (and still sometimes is but it is possible to get human insulin with medical advances). And close enough that they can catch both human flus and avian flus. The danger becomes if a pig has both viruses present. The viruses can then mutate into something that is dangerous and totally new. At the moment it is fairly difficult to get infected by H5N1 virus although it has a high mortality rate when humans are infected.

The reason that pigs are a real danger to avian flu becoming a human flu is on medical sites. The CDA section on flu's note that

Pigs can be infected with both human and avian influenza viruses in addition to swine influenza viruses. Infected pigs get symptoms similar to humans, such as cough, fever, and runny nose. Because pigs are susceptible to avian, human and swine influenza viruses, they potentially may be infected with influenza viruses from different species (e.g., ducks and humans) at the same time. If this happens, it is possible for the genes of these viruses to mix and create a new virus. For example, if a pig were infected with a human influenza virus and an avian influenza virus at the same time, the viruses could mix (reassort) and produce a new virus that had most of the genes from the human virus, but a hemagglutinin and/or neuraminidase from the avian virus. The resulting new virus would likely be able to infect humans and spread from person to person, but it would have surface proteins (hemagglutinin and/or neuraminidase) not previously seen in influenza viruses that infect humans. This type of major change in the influenza A viruses is known as antigenic shift. Antigenic shift results when a new influenza A subtype to which most people have little or no immune protection infects humans. If this new virus causes illness in people and can be transmitted easily from person to person, an influenza pandemic can occur.

The article further notes that flus can change in two ways. [The second way]The other type of change is called "antigenic shift." Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in new hemagglutinin and/or new hemagglutinin and neuraminidase proteins in influenza viruses that infect humans. Shift results in a new influenza A subtype. When shift happens, most people have little or no protection against the new virus. While influenza viruses are changing by antigenic drift all the time, antigenic shift happens only occasionally. Type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift is through.

Are pigs carrying flu superbug?

Anjana Ahuja
February 20, 2004

....Previous research by Jeffery Taubenberger at the US Armed Forces Institute of Pathology has shown that the 1918 flu strain is unlike any other human strain but is very similar to a swine virus. That has lent support for the so-called mixing vessel theory that to become really deadly in humans, avian flu must go via pigs, where it combines with portions of the human flu virus already present. However, there is no proof of this.
....Birds and people, he explains [Karl Nicholson], have different receptors in their airways, and a virus primed to infect one species will generally not be able to infect the other. Pigs, however, are vulnerable to both....
....Nicholson says: “The idea is that these viruses can mix together in pigs, because pigs are susceptible to both. Farming practices being what they are, you often have pigs and poultry close to each other. Sometimes they even live in the same household, with the farmer living upstairs and the animals living downstairs. There i’s the fear that there will be some mixing in pigs...
....Virologists note a similarity between the 1918 virus and swine fever, but they cannot rule out the possibility that people infected pigs rather than the other way round....

an abtract for An Avian Connection as a Catalyst to the 1918-1919 Influenza Pandemic by James E. Hollenbeck is that

The 1918 Influenza pandemic was one of the most virulent strains of influenza in history. This strain quickly dispatched previously held theories on influenza. World War One introduced new environmental stresses and speed of dissemination logistics never experienced by humans. In light of new phylogenic evidence the cause of this influenza outbreak is now being considered to have linkage to the avian influenza. Animals act as reservoirs for this influenza virus and research indicates the influenza virus often originates in the intestines of aquatic wildfowl. The virus is shed into the environment, which in turns infects domestic poultry, which in turn infects mammalian hosts. These animals, usually pigs, act as a transformer or converters; creating a strain that can more readily infect humans. Therefore swine can be infected with both avian and human influenza A viruses and serve as a source for infection for a number of species as the incidents of direct infection from birds to humans have been rare. Increased human habitation near poultry and swine raising facilities pose greater influenza outbreak risk. It was this combination of environmental factors that may have contributed to the greatest pandemic of recent times, and, moreover, similar conditions exist throughout Southeast Asia today.

Now there is as of yet no proof that pigs having an avian virus and a human virus are what cause the 1918 pandemic but there is serious discussion regarding that possibility. And the virus from the 1918 flu has been found in pigs (see above quote).

Now i like bacon a fair bit and some other cuts of ham. However i wonder, given the current world problem with avian flu, if wises wise to continue to raise pigs, especially not in contained areas or close to birds. Should the government not look at this as a possible danger spot? It could order that pigs and chickens not be raised in the same farm or nearby each other if they are on the same farm.

In reality though it is most likely that the genetic shift that could happen in pigs would occur in countries that already have the H51N virus endemic.What i don't understand is why none of this is getting all that much news. It would be hard to get small family farms to give up pigs as a food source because they are more important. Personally I'm much more worried about this than the fact that the virus is appearing in Europe. It's almost a certainty that the virus will move from country to country as birds migrate. But the eruptions of bird flu in Europe are receiving a lot of attention at the moment while almost no mention is made that the virus has jumped to pigs. In my opinion if you want a barometer for if the flu is becoming particularly dangerous to humans, that pigs have it is a much worrisome sign, even if it isn't frequent yet. It's not that countries shouldn't take action to try and get the bird flu out of their country at least for the meantime, but i think the news focus hasn't focused on where one of the largest danger lies.

It has been my thought for over a year that Canada should be helping countries that are being hit by avian flu, especially those where it is a major subsitence issue. While this will still help we missed the gun and the virus is endemic in the region now. However if "western" countries provided more aid that could only clearly benefit chicken owners (such as replacement chickens not money) it would help curb the spread of the flu. If you are going to loose a good part of your food are you as likely to report it to the government? I don't think providing chickens solves all the issues, but then i don't see many countries providing chicken either.

Certainly pigs aren't anywhere near the final answer but they are an issue that i don't even see discussed in Canada. And they are an important one. Yes the next flu may well not be related to this avian flu. But why increase the chances occurring. Perhaps replacing pigs as well as chickens in countries where they are likely most of your meat would help. P