Bird Flu and Other Influenzas Affecting Man and Dog

Bird Flu and Other Influenzas Affecting Man and Dog

Since December 2014, APHIS (Animal & Plant Health Inspection Service of the US Dep’t of Health) has confirmed hundreds of cases of “Highly Pathogenic Avian Influenza” (HPAI), H5N2 variety, in US commercial and backyard poultry flocks, and in wild birds. The Centers for Disease Control and Prevention (CDC) considers the risk to the general public from these HPAI H5N2 infections to be low, with no human cases of these specific viruses detected in the world. (Yet!)  

There is good scientific reason for us to add that “yet” word, and I’ll try to explain why, while still cautioning you not to panic like Chicken Little, aka Henny Penny (Ask the oldest person you know who that was). Viruses make up a class that act somewhat like molecules and somewhat like cells, being intermediate in size, as well. They reproduce (multiply) by splitting, the way most body cells do, but they also break apart and reunite in different configurations the way chromosomes do. In way of over-simplifying the picture, imagine viruses as long chains composed of snaps like those on the end of your dog’s leash. Now imagine each chain as being of a different color and shape—some brass, some chrome-plated, some stainless steel, etc.

On your table, lay one of those chains across one of a different type and color, forming an X design. Say a brass one of certain size clasps lying in a Northwest-to-Southeast direction, and a stainless one that has different design segments, lying NE-to-SW. Now, unhook both chains where they lie across each other, and hook the two segments on the west side of your table together, and do the same with the east-side segments. Now you have chains that are part brass, part stainless steel. They look and “act” different than their “parents.” Cousin Jimmy who is visiting you is partial to stainless, so he picks up one of the new chains by the stainless end and makes a belt or necklace of it. Your pet Capuchin monkey prefers the look of brass, so he wears one of the same chains, after picking it up by the coppery-colored end. Neither of them has ever had any affinity for “the other color” before, but now both of them “are infected” by (connected, attached to) the same mutated chain that we call a virus. The other way new viruses appear is when they mutate spontaneously, without any obvious “crossbreeding” with other species.

Coronaviruses are common viruses that most people and many animals get at some time or other. The name for this wide variety comes from the crown-like spikes on the particle’s surface. Human coronaviruses usually cause mild to moderate upper-respiratory tract illnesses. The coronavirus that causes Middle East Respiratory Syndrome (MERS) was quickly isolated to the Saudi Arabia peninsula and a few other places. SARS was a much more serious coronavirus.

When such a “new form” like 2015’s bird flu H5N2 appears, there is a possibility that it can suddenly affect species that previously had not been affected by either parent virus. New combinations of HPAI, like any virus—influenza or whatever—can occur easily. Part of the reason is the simplicity of a virus particle compared to the complexity of a gene. So far, this has not happened with the latest “avian” virus that is driving the prices of chicken, turkey, and eggs through the roof of the henhouse. But we cannot tell if or when it might. As the USDA says, “New strains can occur naturally at any time within avian hosts. The concern is whether the changes would impart the potential to cause severe disease or increase transmissibility between birds or mammals. Liquid egg prices have shot up 240 percent because the center of the lethal bird flu outbreak was in Iowa, the country’s largest egg-producing state.” The outbreak of highly transmissible H5N2 flu has now spread to nearly half of the lower-48 states, infecting over 300 sites. Canada geese, which now plague public parks and private grounds all across the US and Canada, are becoming carriers.

In the inheritance complexity we see in more complex organisms—mammals, for example—there is a tendency for the mutant to be non-viable. Severely deformed babies have greatly reduced chances of surviving, even in utero. Hybrids such as zebra-donkey, horse-jackass, lion-tiger, and others have varying possibilities of being fertile (usually not) or of surviving gestation, even if the sperm of one species is able to penetrate the cell wall of another’s ovum. Different numbers of chromosomes, numbers and structures of genes, and other dissimilarities are formidable barriers. Once in a great while, however, your key will start a stranger’s car or open a house hundreds of miles away.

Meanwhile, the new avian flu has not progressed to any ability to mutate into anything dangerous. Hopefully, it will die out or be controlled enough so the risk becomes extremely low. Otherwise, we may see it develop an ability to co-infect, as did H1N1 (so-called Swine Flu) which may have been transmitted directly from birds to humans. Other viruses, however, might pose a bigger danger to us and our pets.

The Hong Kong flu of 1968-69 was the first known outbreak of a strain designated H3N2, though it probably evolved from the H3N1 of the late 19th century and the more recent H2N2, and shared genes with the 1957 Asian flu. The Hong Kong flu nearly did me in. I was unable to get out of bed or sit up for over a week, and was nursed back to life by my wife who somehow escaped symptoms (as did my dogs). Every day, we expected it to end the way any less debilitating “cold” would have, so we did not go to the hospital. I think the reason I was near death was that I had not contracted the similar H2N2 (Asian flu) in 1957 and thus had no antibodies that could fend off the 1968 close relative. But cross-immunity between subtypes of influenza is poorly understood. Only one strain of the Hong Kong flu caused an influenza-like illness in calves.  

In the past couple decades, I have judged dog shows in China nearly every year. On one of those trips, in the spring of 2003 I was judging in Shenzhen, close to Hong Kong, when an outbreak that came to be known as SARS (Severe Acute Respiratory Syndrome) hit its peak with an eventual 8,096 cases in nearly 40 countries (the majority in Hong Kong) and almost a 10% fatality rate. It raged between November 2002 and July 2003 because of the Chinese government’s foot-dragging in regard to admitting and then fighting it. On the way to the airport after my assignment and visit, the officials were taking temperatures of everybody crossing the HK-China border. I was on the very last flight that left Hong Kong, barely getting off the runway when China closed the borders and did not allow any more departures for some days.

SARS has a zoonotic origin, which means that it crossed the boundary from one animal species to another, and is caused by the SARS coronavirus (SARS-CoV). It wasn’t until some months after my judging assignment that wild animals sold for food in the local markets of Guangdong were found to be the source of the SARS outbreak. Especially an animal called the palm civet, a wildcat between the size of a house cat and a tiger. Some of the cats showed no signs, but when the virus crossed the xenographic (foreign-dissimilar species) barrier from palm civet to humans, it knocked our species there for a loop. Another danger or cause for concern, not played up in the news, is the possible permanent alteration to the genetic code of the animal (human?) acquiring the virus—via some of the genetic data of the donor. It sounds very sci-fi, but would make a great Hollywood movie! A few successful cases of xenotransplantation are published, but so far, it is only tissue (such as pig valves in heart-surgery patients), not any gene-transfer.

Flu viruses can mutate a great deal faster than whole-animal mutations, and are constantly changing, which is why getting a flu shot at the drug store mostly protects you from last year’s mutation, not all the new ones—a waste of money in my mind, but don’t let me stop you. That gradual change is called aintigenic drift, while antgigenic shift refers to the “crossbreeding” of two flu types and hits you too suddenly for last year’s vaccine to do any good. An example of a shift would be if a bird flu virus happens to be accepted by an intermediate host such as a pig that has also been exposed to a human strain of flu, then this new combined strain is passed to a human who has no immunity to this interspecies virus. A flu strain could also jump from wild bird to pig to human without that pig having first received anything from a human.

Keep watching the news, because the list is changing almost daily. You will likely read or hear about flu viruses such as H5N1 (Avian/Bird Flu), H1N1 (Swine Flu), H3N2v, and H7N9. H2N2 (Asian) & H3N2 (HK) pandemic flu strains contained genes from avian influenza viruses. The variety called H3N2v usually spreads to humans from infected pigs—such as after contact with pigs at county fairs, but it also has spread between people. Human infections with a new avian influenza-A virus called H7N9 continues to be reported in China—this one in humans with some fatalities, as well as poultry. If you do travel to affected regions, be very careful to wash hands often, bow instead of shaking hands or kissing, and take other such common-sense hygiene precautions.

 

Ed. Note:  Fred Lanting has lectured and judged dog shows in over 30 countries, and is the author of numerous books and countless articles, many of which deal with his avocation in “All Things Canine.”  

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