Cats Infected With H7N2 - NYC 2016
#16,790
Ten days before Christmas 2016, the New York City Health Department issued an unusual Statement On Avian H7N2 infecting Cats at a Manhattan animal shelter. How the virus was introduced into this feline cohort is unknown.
H7N2 strain has caused mild illness in cats in Manhattan shelter and is thought to pose a low risk to humans
The Health Department is contacting persons who recently adopted Manhattan shelter cats
December 15, 2016 – The Health Department and the Animal Care Centers of NYC (ACC) today announced that a strain of influenza A virus, known as low pathogenic avian influenza H7N2, has been identified in 45 cats housed at the Manhattan shelter.This is the first time this virus has been detected and transmitted among domestic cats. It is unknown how the cats contracted the virus. So far this virus causes mild illness in cats and is thought to pose a low risk to humans.
The plot would continue to thicken over the holidays when 7 days later, the NYC DOH released a statement announcing a mild Human H7N2 Infection in a veterinarian who was treating sick cat. Eventually, more than 400 cats - across multiple facilities - were said to have been infected.There have been only two documented human cases of low pathogenic avian influenza H7N2 infection in the United States – one in a farmer who worked closely with chickens in 2002 and the other with an unknown source in 2003. Both of these patients recovered.
At the time, the CDC wrote:
Why is CDC concerned about H7N2?
As part of CDC’s mission to protect the public from emerging health threats, CDC monitors changes in flu viruses found in human and animal populations. Finding a bird flu virus in an unexpected animal, like a cat, is always concerning, because it means the virus has changed in a way that may pose a new health threat. Animal viruses that gain the ability to infect humans are especially concerning because most people will not have existing immune protection against such viruses.
Also, there is potential for a pandemic (a global outbreak of disease) to occur when a new animal virus gains the ability to infect humans and also has the ability to spread efficiently from person to person. For these reasons, these incidents must be carefully investigated and appropriate actions taken to ensure that there is no ongoing spread of the novel virus among people.Since then, we've seen a number of studies on the biological `fitness' of this avian H7N2 virus (here, here, and here), along with evidence (see J Infect Dis: Serological Evidence Of H7N2 Infection Among Animal Shelter Workers, NYC 2016) confirming at least 2 employees had been infected, while 5 others exhibited low positive titers to the virus, indicating possible infection.
H7N2 wasn't quite ready for prime time six years ago and was quickly contained - but it demonstrated worrisome traits =, and remains the subject of ongoing research.
All of which brings us to a new study - published this month in the journal Viruses - which explores mutations that could increase H7N2's growth in human human respiratory cell cultures, and potentially improve its ability to spread from human-to-human.
This is a lengthy and highly detailed report, and I've only excerpted the abstract and parts of the discussion, so follow the link to read it in its entirety. I'll have a postscript when you return.
Adaptation of the H7N2 Feline Influenza Virus to Human Respiratory Cell Culture
Wataru Sekine, Akiko Takenaka-Uema, Haruhiko Kamiki, Hiroho Ishida, Hiromichi Matsugo,
Shin Murakami and Taisuke Horimoto *
Laboratory of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
ABSTRACT
During 2016–2017, the H7N2 feline influenza virus infected more than 500 cats in animal shelters in New York, USA. A veterinarian who had treated the cats became infected with this feline virus and showed mild respiratory symptoms. This suggests that the H7N2 feline influenza virus may evolve into a novel pandemic virus with a high pathogenicity and transmissibility as a result of mutations in humans.
In this study, to gain insight into the molecular basis of the transmission of the feline virus to humans, we selected mutant viruses with enhanced growth in human respiratory A549 cells via successive passages of the virus and found almost all mutations to be in the envelope glycoproteins, such as hemagglutinin (HA) and neuraminidase (NA).
The reverse genetics approach revealed that the HA mutations, HA1-H16Q, HA2-I47T, or HA2-Y119H, in the stalk region can lead to a high growth of mutant viruses in A549 cells, possibly by changing the pH threshold for membrane fusion. Furthermore, NA mutation, I28S/L, or three-amino-acid deletion in the transmembrane region can enhance viral growth in A549 cells, possibly by changing the HA–NA functional balance.
These findings suggest that the H7N2 feline influenza virus has the potential to become a human pathogen by adapting to human respiratory cells, owing to the synergistic biological effect of the mutations in its envelope glycoproteins.
(SNIP)
Discussion
In the incidents reported so far, avian IAVs have been directly transmitted from infected poultry to humans, leading to disease and death of infected persons [26]. However, there has been no pandemic as a result of this situation, possibly because of the lack of emergence of mutant viruses that could be efficiently transmitted among human populations. Historically, pandemic viruses have emerged via pigs as an intermediate host by mutations and reassortments with avian, swine, and human viruses, because pigs are susceptible to both avian and human viruses [2,27,28].
Cats are also susceptible to both viruses [8,9,10,11,12,13,14,15] and have close contact with humans as companion animals, providing the potential to act as an intermediate host for the emergence of a novel pandemic virus. In this study, to gain insight into this potential, we investigated the molecular basis for the adaptation of avian-derived H7N2 feline IAV to human respiratory A549 cells. We found that mutations in both the HA stalk and NA transmembrane regions were able to synergistically enhance the growth rates of H7N2 feline IAV in A549 cells, suggesting its potential to sporadically evolve into a human pathogen, causing a pandemic, by adapting to human respiratory cells.
(SNIP)We conclude that the H7N2 feline IAV has the potential to become a human pathogen by adapting to human respiratory cells, owing to the synergistic biological effect of mutations in the envelope glycoproteins. Our findings may contribute to the prediction and assessment of the risk of animal viruses for the emergence of a pandemic virus.
No one really knows whether H7N2 (or any other novel flu virus) has the `right stuff' to spark the next pandemic. What we do know is that viruses surprise us all the time.
- Prior to 2003, coronaviruses were viewed as being weak and incapable of sparking a pandemic, but today we know different.
- Until 2014, `conventional wisdom' stated that Ebola was too deadly to spread beyond the remote villages in Central Africa. That is would `burn itself out'. Then we saw a multi-country outbreak in West Africa which shattered all expectations.
- Three months ago, the idea that we'd have a global outbreak of Monkeypox - one which flew under the radar undetected for weeks or even months - would have been scoffed at.
All three of these examples gave us ample early warnings of what was to come, but they were largely ignored. Much as we have ignored (or only given lip service to) pandemic preparedness.
New disease threats appear to be emerging at an ever increasing rate - and like the plate spinners on the Ed Sullivan Show of 50 years ago - public health agencies are courting disaster and pushing their limits (and luck) with every passing day.
In recent years surveillance, and reporting, on novel virus outbreaks around the world has deteriorated . Part of that is due to the demands of the pandemic, but there were serious signs of erosion long before COVID appeared (see Adding Accountability To The IHR).
Despite the old adage; what we don't know, can hurt us.
Meaning we need to make pandemic preparedness - for whatever comes next - a national priority. And we need to do it today. Because time and viruses wait for no one.
