How the owner can infect a pet

Vomiting, shortness of breath and diarrhea are symptoms of the Belgian cat that appeared one week after the owner became aware of his positive SARS-CoV-2 status. Tests showed Zoönotisch risico van het SARS-CoV2 virus (Covid-19) bij gezelschapsdieren: infectie van dier naar mens en van mens naar dier that the vomit and feces of the animal contain the genome of the new coronavirus. Considering that the Hong Kong government reported Detection of low level of COVID-19 virus in pet dog about Pomeranian and German Shepherd dogs with positive test results, and the United States confirmed If You Have Animals a case of human-to-animal transmission of the virus (the tiger was unlucky USDA Statement on the Confirmation of COVID-19 in a Tiger in New York at the New York Zoo) - the owners of four-legged pets, to put it mildly, tensed.

"The WHO is now analyzing data that cats - including tigers - and ferrets can become infected with coronavirus from humans, and dogs, with a high degree of probability, are immune, - says a professor at the Research Institute of Epidemiology and Microbiology. N. Gamalei Alexander Sanin. - In total, the coronavirus family has about 40 species. Feline Coronavirus (FCoV) RT-PCR cats, dogs and ferrets, like other animals such as bats, pigs and cattle, have their own coronaviruses that only infect them. A cat infected with the human coronavirus is unlikely to get sick, although minor symptoms such as coughing or sneezing, upset stomach may occur."

The test for the presence of the SARS-CoV-2 genome in vomit or feces does not yet show whether the virus is capable of truly infecting the animal (that is, entering the cells and starting to multiply) - it shows that the viral particles just got into the cat.

To better understand the possibilities of the new coronavirus and further overcome interspecific barriers, scientists from Harbin in the laboratory infected Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS-coronavirus 2 with cats, dogs, ferrets, pigs, chickens and ducks. Subjects were injected through the nose with a large amount of pathogen, which in real life they would hardly have encountered. As a result, chickens, ducks and pigs did not show the presence of the virus, in two dogs out of five pathogens were found in the feces, but in cats, particles got into the tissues of the upper respiratory tract and lungs. Moreover, the animals infected by the scientists managed - without showing symptoms of the disease - to infect one of three healthy cats, which were settled in a neighboring cage.

The scientific community reacted to this Coronavirus can infect cats - dogs, not so much ambiguous: the sample is small, the doses of the pathogen are too large for real situations (105 plaque-forming units of SARS-CoV-2 were introduced per milliliter; and although we have not yet received the minimum dose for infection we know REQUIRED INFORMATION FOR EFFECTIVE INFECTIOUS DISEASE OUTBREAK RESPONSE, for the development of the first SARS it was necessary from 67 to 540 pfu / ml). In addition, the conditions for keeping cats in the article were not particularly specified, so the route of transmission of the virus is also unclear.

In general, the path “from animals to people” is popular among diseases: 60 percent of new infectious diseases that humans have received over the past half century have come to us in this way Global trends in emerging infectious diseases - including the same new coronavirus.

Infections inherited by Homo Sapiens from other representatives of the fauna are called zooanthroponoses. Zooanthroponoses - "Wikipedia" or simply zoonoses. Caring mothers are afraid of them, forbidding children to touch homeless cats - carriers of helminths, toxoplasma, trichophyton fungi, salmonella, chlamydia and the rabies virus. Global shifts in mammalian population trends reveal key predictors of virus spillover risk 11.4% of all species of terrestrial mammals - mainly rodents, bats, primates, artiodactyls and carnivores.

As for the reverse scenario, in 2014 PLOS ONE magazine published a review of Reverse Zoonotic Disease Transmission (Zooanthroponosis): A Systematic Review of Seldom-Documented Human Biological Threats to Animals of scientific articles on reverse zoonoses: over the past 30 years, they have been registered in 56 countries on all continents except Antarctica. In total, 21 publications in the report were devoted to the successful transmission of bacteria, 16 - viruses, 12 - parasites, 7 - fungi, the rest - to other pathogens or cases of complex infection.

Do cats have coronavirus: where were cases of reverse zoonosis recorded?

The review authors noted that the number of reverse zoonoses may increase in the future. Man continues his invasion of the territory of wild animals, the international trade in meat and other products is developing, the zoo industry is growing - new zoos and aquariums are opening. But today, reverse zoonoses are still rare - even among cats, which are especially close to humans. However, in some cases, cat lovers should still refuse close communication with their wards.

Changing the owner

Before SARS-CoV-2 got close to the pets, it succeeded in other interspecific races. Apparently, man got it The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2 from a bat through an as yet unclear SARS-CoV-2 spike protein favors ACE2 from Bovidae and Cricetidae intermediate host … And this is far from the first such case: Ebola fever apparently infected us with Fruit bats as reservoirs of Ebola virus, bats, Middle East respiratory syndrome (MERS) - camels Evidence for Camel-to-Human Transmission of MERS Coronavirus, and for the previous coronavirus (SARS-CoV), which caused SARS in China in 2002–2003, the intermediate host was most likely the Himalayan civets Bats, Civets and the Emergence of SARS.

For a virus to spread from one species to another, three conditions are required.

“Firstly, the virus needs to meet with a new host, and this does not always happen,” explains Alexei Potekhin, professor at the Department of Microbiology at St. Petersburg State University. - It is easy to assume that some pathogens are ready to jump from sight to sight, but their hosts simply do not meet with each other. For this reason, people got many viruses from animals while hunting - there was a reason for contact."

The second problem that the virus will have to solve is finding a suitable receptor. Coronaviruses enter animal cells thanks to S-proteins, which form the very "crown" around the virus particle. SARS-CoV-2 with their help binds to the ACE2 receptors SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor on the surface of host cells. In general, S-proteins in different types of coronavirus are "tuned" to the cellular receptors of different animals, so that it is easier for the pathogen to infect precisely "its" victims - bats, cats, pigs, and so on. However, in the process of reproduction, the virus copies its own RNA a huge number of times, and mutations inevitably occur in the copies.

Scheme of entry of SARS-CoV and SARS-CoV-2 into the cell

As a result, one of the millions of viral particles may have an S-protein that will be able to firmly cling to a cell receptor of another species and will be able to get into the cells of a new host. And the more particles of the "human" virus surround the same cat, the more chances that there will be at least one that is ready to turn into a new feline pathogen. Still, as Potekhin notes, this process is similar to a game of roulette, with the vast majority of losing combinations in it, and almost no winning ones.

SARS-CoV-2 tends to bind SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor to ACE2 receptors - which are found in many animals, from humans to roundworms.

This does not mean that a huge number of species will now begin to infect, get sick and spread the virus further.

Because there is a third condition - the virus needs to be able to multiply as efficiently in the cells of the new host, and here the mutation roulette should again give out a winning combination, which happens extremely rarely twice in a row.

Today, Potekhin explains, there is still no convincing evidence that SARS-CoV-2 was able to overcome the interspecies barrier from person to cat: the cases that have become known should still be attributed to anecdotal evidence.

First, there are still no peer-reviewed scientific articles confirming that not the viral genome was found in the body of cats, but the viral subgenomic RNA - a sure sign of the multiplication of the pathogen in the cells. Secondly, the microbiologist notes, the preprint of SARS-CoV-2 neutralizing serum antibodies in cats: a serological investigation that antibodies to SARS-CoV-2 are found in the blood of cats is hardly proof: it is not known exactly which feline antibodies able to communicate with a new type of coronavirus, this needs to be investigated, and ideally - to develop their own test systems for cats. Thirdly, even after getting to a new owner, it is not at all necessary that the virus will be able to multiply in sufficient quantities to infect other cats or humans. Perhaps every cat will be a dead end for the pathogen.

“Ever since the experiments of Louis Pasteur, we know that when a virus is transmitted to a new host for an old pathogen, it becomes weaker - this process is called attenuation,” the scientist explains. - With its help, the great scientist weakened the canine rabies virus in the organisms of rabbits, so that later he could make a “vaccine” for humans. That is why, even if a huge number of accidents happen and the cat can still be the host for SARS-CoV-2 (for which there is no strong evidence yet), then this feline variant of the virus will almost certainly be greatly weakened for the return transmission to the person. Usually the virus causes more trouble to the new owner, so in this sense we are now more dangerous for cats than they are for us."

What a person can share with a cat

Influenza viruses

In the spring of 2009, a resident of Iowa - a 13-year-old domestic cat - suddenly felt unwell. He did not want to play, his nose warmed up, and his favorite food no longer aroused appetite. On the fourth day of the feline illness, the family, themselves suffering from fever, cough and muscle pain, took the animal to a veterinary center - and found out a strange thing. H1N1 RNA found in cat lung fluid. The cat was sick Influenza A Pandemic (H1N1) 2009 Virus Infection in Domestic Cat with swine flu.

Do cats have coronavirus: chest x-ray of a cat from Iowa

Fortunately, this confusion ended well for him - after a couple of days the cat recovered. But some other pets were less fortunate in those years. Oklahoma veterinarians treated two cats exposed to the H1N1 influenza virus with Acute bronchointerstitial pneumonia in two indoor cats exposed to the H1N1 influenza virus, whose owner recently had a flu-like infection. The animals were diagnosed with severe pneumonia, and later its cause was again the H1N1 virus. Despite analgesics, diuretics, corticosteroids and artificial ventilation of the lungs, they could not be saved.

In general, for a long time it was believed that cats are resistant to influenza - until in 2003 in Asia there was an outbreak of bird flu H5N1: people began to report dead animals, and soon this feline weakness was confirmed by Avian H5N1 Influenza in Cats experimentally. H5N1 can occasionally affect other felines: during another outbreak in Thailand at the Suphanburi zoo, two tigers and two leopards died from this pathogen Probable Tiger-to-Tiger Transmission of Avian Influenza H5N1, and five more tigers in the Siraca Tiger Zoo. The animals were fed raw chicken carcasses, which were apparently contaminated. However, we can infect a cat with avian flu only by bringing it "in our hands" (people do not get sick with it, despite the fears of WHO bird flu), but it is known that cats can also be infected with H3N2 and H7N7 viruses Highly Pathogenic Avian Influenza Virus H7N7 Isolated From a Fatal Human Case Causes Respiratory Disease in Cats but Does Not Spread Systemically.

Methicillin-resistant Staphylococcus aureus

This superbug is one of the winners of the competition between microorganisms and antibiotics - a common cause of nosocomial infections. There are many people in hospitals who are given broad-spectrum antibiotics, and that's why such dangerous super-soldiers with the genetic armor from penicillins and cephalosporins appear there. MRSA carriers are often medical Prevalence of methicillin-resistant Staphylococcus aureus colonization among healthcare workers and healthy community residents, including veterinarians Methicillin-resistant Staphylococcus aureus Colonization in Veterinary Personnel.

Researchers at the University of Missouri College of Veterinary Medicine tested the Prevalence of Staphylococcus aureus and Methicillin ‐ Resistant Staphylococcus aureus Carriage in Three Populations on 586 human-pet (cat or dog) pairs of MRSA: 211 veterinarians, 162 paramedics, and 213 non-healthcare people. In total, the same MRSA strain was found in four pairs. This suggests that cases of infection between species are still quite rare. However, it is important to note that the study involved guests of the forum of veterinary doctors - that is, people who knew better than others how to protect an animal from infections.

Staphylococci are often part of the normal microflora of humans and animals. However, its resistant forms, sometimes skipping Evidence of multiple virulence subtypes in nosocomial and community-associated MRSA genotypes in companion animals from the upper midwestern and northeastern United States from humans to cats or dogs, can cause skin rashes and even non-healing wounds in weakened animals …There is another danger: even if the cat does not show symptoms, it can become a reservoir of Clinical, microbiological, and molecular characterization of methicillin-resistant Staphylococcus aureus infections of cats for resistant bacteria and continue to infect family members who are trying to get rid of the infection. This is why effective treatment for MRSA involves not only medications for the patient, but also antibacterial agents for all of his household, including the Methicillin-Resistant Staphylococcus aureus in a Family and Its Pet Cat, if it is a carrier.

Tuberculosis

Both the cat Feline mycobacterial infections and the human Guidelines for speciation within the Mycobacterium tuberculosis complex. Second edition can be infected with bovine tuberculosis caused by the bacterium Mycobacterium bovis Mycobacterium bovis - "Wikipedia". A domestic animal has three ways to become infected: drink raw milk, eat the meat of a sick animal, or catch a bacterium on the mucous membrane - through a bite, an open wound, and also by airborne droplets. Therefore, if a person with Mycobacterium bovis intentionally sneezes at his cat (of course, this should not be done in any case!), Then he can achieve "success."

Candidiasis

The yeast-like fungus Candida albicans is a frequent inhabitant of Chapter 115: Candida, Cryptococcus, and Other Yeasts of Medical Importance of normal animal flora. In humans, it can cause many troubles - from thrush to damage to internal organs due to invasive candidiasis, and it is not very common in veterinary medicine. If the body of the animal is severely weakened, as in dogs with Systemic Candidiasis in an Apparently Immunocompetent Dog, and in cats with Ocular and disseminated candidiasis in an immunosuppressed cat, systemic candidiasis can manifest itself, affecting several internal organs at once. There are also known cases of infection of Risk factors for Candida urinary tract infections in dogs and cats of animals with Candida albicans, resistant to antifungal drugs.

A cat can be a carrier of its owner's fungus. Veterinarians from the University of Illinois tested the Molecular Phylogenetic Analysis of a Geographically and Temporally Matched Set of Candida albicans Isolates from Humans and Nonmigratory Wildlife in Central Illinois 89 representatives of domestic fauna, slightly less than half of which were cats, and found a fungus on the mucous membrane of 11 animals, genetically related the human version. Although the chance that she will feel unwell from this is small.

Giardia

At first glance, the intestinal parasite Giardia lamblia does not seem to be particularly picky in choosing a host: it can live inside a person, a bird, a rodent, a dog, a cat, and many wild animals. Experiments show Infectivity of Swiss Giardia isolates to jirds and mice, and in vitro cultivation of trophozoites originating from sheep, that, for example, feline giardia can infect birds, and sheep can infect mice. Yet this flagellar protist is not so simple: it has eight genetic subtypes Zoonotic potential of Giardia, and variants A and B prefer to settle in Homo sapiens, C and D in dogs, F in cats.

Employees of the Laboratory of Zoonoses and Environmental Microbiology of the National Institute of Public Health and the Environment of the Netherlands conducted a large-scale study Identification of Zoonotic Genotypes of Giardia duodenalis, in which they studied the genetic characteristics of Giardia lamblia in almost 2,500 people and animals. There were 158 cats among them, and a third of them turned out to be home to the human variant. Genotype F was found in about the same number of cases.

Gastritis, ulcers and other Helicobacterial problems

Gastritis and ulcers, which were considered the lot of nervous spicy food lovers half a century ago, are very often the result of infection of the stomach with Helicobacter pylori bacteria. It is believed that cats may have the same problems and other "stinging" bacteria are to blame for them - but there is a suspicion of A mixed population of Helicobacter pylori, Helicobacter bizzozeronii and “Helicobacter heilmannii” in the gastric mucosa of a domestic cat and that sometimes the pest can be Helicobacter pylori, inherited from the host. For example, Iranian scientists have successfully infected EXPERIMENTAL INFECTION OF STRAY CATS WITH HUMAN ISOLATES OF HELICOBACTER PYLORI with human cat bacteria, and their other colleagues found Failure to isolate Helicobacter pylori from stray cats indicates that H. pylori in cats may be an anthroponosis - an animal infection with a human pathogen strains of human helicobacteria in domestic cats and were not found in stray cats. This means that anthroponosis is quite possible.

Bonus: smoking harms his health too

Smoking, of course, is not an infection, and a domestic cat is unlikely to pick up the bad habit itself from the owner, but the tobacco smoke that a smoker owner produces can harm the health of the animal. This can be seen from a simple analysis of Urinary biomarkers to assess exposure of cats to environmental tobacco smoke urine: healthy cats living with smokers have approximately 14 times more nicotine in their urine, 11 times more nicotine, its metabolite cotinine, and 3 times more carcinogen. NNAL, which is associated with lung cancer development in humans Urinary levels of cigarette smoke constituent metabolites are prospectively associated with lung cancer development in smokers and animals.

As QUIT SMOKING FOR THE SAKE OF YOUR PETS veterinarians at the University of Glasgow found out, cats suffer more from secondhand smoke than dogs, due to their habit of often licking their fur, on which particles of cigarette smoke can settle. In addition, smokers' pets are more likely to gain weight after castration, and it is not so important whether they live in an apartment or can periodically ventilate on the lawn of a country house.

And the most unpleasant thing: cats forced to breathe tobacco smoke have a 2, 4 times higher risk of getting one of the most common types of feline cancer - malignant lymphoma. If a pet has been living with a smoker for more than five years, the risk is higher than Environmental Tobacco Smoke and Risk of Malignant Lymphoma in Pet Cats by 3, 2 times and continues to grow with increasing length of service. There is research showing a link between host addiction and the development of p53 expression and environmental tobacco smoke exposure in feline oral squamous cell carcinoma in cats with squamous cell carcinoma of the mouth - possibly due to licking.

Take care of the cats

Since cats can spread many other diseases among people, and a person in rare cases can reward his furry friend with some kind of infection, it makes sense to follow the rules of hygiene - this will reduce the risks of infection for both species. Felinologist Olga Syatkovskaya, a member of the International Society for the Study of Infectious Diseases of Domestic Animals (ISCAID), advises to behave with a cat as carefully as with people.

“If a person has a cough or a runny nose, he needs to wear a mask to protect others, including animals, from infection,” Syatkovskaya said. - During such periods, it is worth less contact with a cat or dog and washing your hands more often. It is important to make sure that the toilets are closed in the house: unfortunately, many pets like to drink water from the toilet, which contains a large number of pathogens. And, of course, in no case should cats be treated with alcohol disinfectants - this is dangerous for animals."