PEOPLE & PET HEALTH
Simple science on Zika virus, Avian flu, viral influenza, how virus replicate, CDC warnings, and how to better protect ourselves and our pets from new outbreaks?
CROSS-SPECIES VIRAL TRANSMISSION RISK
Fred Lanting, International All-Breed, Sieger/Schutzhund Judge
CDC has issued Zika Virus warnings for people traveling to Brazil for the Olympics this September and last year APHIS (Animal & Plant Health Inspection Service of the US Dep’t of Health) confirmed hundreds of cases of “Highly Pathogenic Avian Influenza” H5N2 variety, in our 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 viruses reproduce (multiply) by splitting, the way most body cells do, but they also break apart and reunite in different configurations the way chromosomes do. 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. Now, unhook both chains where they lie across each other, and hook the two segments on the right and do the same with the two on the left. Now you have two 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 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.
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 mutate.
As the USDA says, “New strains can occur naturally at any time within avian hosts. The concern is whether the changes would allow transmissibility between birds or mammals. The fear factor increases as "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 species’ 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, 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. Other viruses, however, might pose a bigger danger to us and our pets. The latest is the Zika virus that will be spread around the world as a result of the Olympic games in Rio de Janeiro.
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, plus genes of 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). 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 close relative in 1968.
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.
In the past two decades, I have judged dog shows in China nearly every year. 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) eventually resulted in 8,096 cases in nearly 40 countries (the majority in Hong Kong). With a 10% fatality rate, SARS raged between November 2002 and July 2003 because of the Chinese government’s foot-dragging in admitting and then fighting it.
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.
When the virus crossed the xenographic (foreign-dissimilar species) barrier from the wild palm civet to humans, it knocked our species for a loop. Another 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 few successful cases of medical xenotransplantation have been published. So far, it has been 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 only protects you from last year’s mutation, not the new ones and is a waste of money in my opinion.
The list of viral mutations changes every year. You will continue to 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.
Fred Lanting is an all-breed judge with experience in over 30 countries. He is a well-known Shiba breeder and GSD authority. He handled Akitas in the 1960s and `70s, and was named an official JKC judge, a rare honor. He has lectured around the world on breeding, judging, canine movement, and CHD (canine hip dysplasis). Be sure to peruse these Dog Books by Fred Lanting