Remind me, why are we doing this? Because cows produce less milk for a week, then recover? Because some dairy workers have a pink eye for a day, then recover? A PCR test alone has never been a conclusive diagnosis for acute illness and never will be. What this will accomplish, is that many false positives will be detected and herds will be placed under quarantine for no reason, putting further stress on the food supply chain... for no reason.
I truly appreciate your response! We need more dialogue among us on what I know is a very contentious topic for many in industry. Let me address several of your points one by one:
1) PCR is a very accurate diagnostic tool for acute infection; I agree that infection does not always equal illness; if often precedes illness, especially with viral diseases like influenza. So a bulk tank test may well become positive days before mastitis appears in the herd. But that doesn't mean that the cows aren't already infected and shedding lots of live virus into the milk supply. Pasteurization is our saving step at this point for the milk; however, workers milking the cows may be at the most risk for infection at this point because no one realizes yet that the cow(s) are shedding virus in the milk.
2) Your comment about some workers having pink eye for a day concerns me. Any viral illness, especially with an agent that is considered potentially a risk for further mutation towards zoonosis should never be minimized. First, pink eye can have serious secondary consequences. Second, pneumonia can also result with much more serious issues. Third, workers may have immune compromised loved ones at home - children, elderly, cancer patients, etc. at greater risk for secondary infections. These are exactly the people the CDC worries most about coming in contact with the virus. Unfortunately, it's the risk of human involvement that requires extraordinary measures for H5N1; we have no way around that.
3) Positive herds are not false positives (except in perhaps rare instances of sampling errors) and quarantines are placed only to protect other herds from exposure to the virus. Milk sales are not disrupted, only movement of livestock without approval during acute phases of illness. No responsible producer wants to give an infectious disease to another producer. Special needs for movement considerations can be negotiated with animal health officials.
4) Finally, we certainly agree about stress on the food supply chain! I'm extremely grateful that all of the safety protocols in place, especially pasteurization all ongoing marketing of safe milk products- I just enjoyed both a cheeseburger and ice cream for lunch.
I don't know if bulk milk testing will be ongoing, expanded to other states, or eventually replaced with other methodologies. however, I'm pretty confident that one way or another our public health officials will expect that we in agriculture continue to monitor the bovine virus for changes in the genetics, as well as protect our workers from exposure. Moreover, the poultry industry will insist on awareness of the risks they face from neighboring cattle operations. We live in a very interconnected world, even in agriculture - transparency is no longer an option.
Thanks again for your comments. I appreciate your willingness to express your frustrations.
I appreciate some of the arguments, but some other require second thoughts.
1) PCR tests can still return positive when illness has been cleared by all medical standards, as it reacts to virus fragments that may still linger in the recovered animal. This comes on top of the false positive rate for the test method itself, which is not zero and which I would like to see announced along with emergency measures.
2) The argument to "protect immune compromised loved ones at home - children, elderly, cancer patients, etc. at greater risk for secondary infections" is entirely moot. There is no known avian infuenza strain that spreads from humans to humans. Therefore, the most stringent measure to take is to make immunocompromised cattle workers wear PPE, if they don't already do so.
3) I appreciate the argument about not passing the virus on to another herd, but we need more information before we take extreme measures. I agree with your point about PSU: universities are the right place to develop a protocol commensurate with the danger. Based on the present set of observations, the danger from this virus is low, to animals and humans alike. Any statement I read that contains exaggerated danger involves some sort of an assumption that 'the virus will mutate to higher morbidity' and/or 'the virus will zoonotically jump to humans,' neither of which has ever happened. So let's cross that bridge when we get there. Which we won't.
You are right about "false positive" PCR's after active infection, when dead virus is still being shed. In fact, when weekly bulk tank sampling is first started in CO, it's possible that recovering dairy herds could test positive, then fairly quickly go negative with no clinical signs if the herd is recovering from infection and mastitis has either passed or was never a part of the clinical illness. So, if the herd never shows clinical illness, the bulk tank should be tested again, hopefully to clear the quarantine. I'd argue that the odds are high that the herd originally had the infection (but not full blown clinical illness, IF there wasn't a sample mix-up). It will be interesting to see how often herds are positive by PCR but show little or no mastitis; I was on a call this afternoon where participants discussed this. The point though is what I discussed in the earlier post - the herd is still infected (likely by respiratory means) but does not develop extensive mastitis. You can argue that is a non-dangerous event, and you have a point. There is much less virus shed, but still enough to trigger a PCR result on a bulk test. Animal movements would still be a threat to other herds, and the positive herd would be a (reduced) threat to workers and nearby poultry flocks.
Once bulk testing is in place and has a track record, new PCR results should indicate NEW infections, not resolving ones, i.e. a positive herd is likely just becoming positive and will become sicker, not recover.
As for your comments about the virus has not mutated to higher morbidity or made the jump to humans more easily, actually that has already happened NOW. The poultry workers are proof positive of that. I agree that the risk of onward transmission is still remote, but we now have some genomic tools to watch the changes in the virus. It is malpractice on our part NOT to do so. I wish we could be doing the same testing worldwide in all areas where H5N1 is raging, but this is one area we do have control.
We don't know which virus in which part of the world will make the jump - it may well NOT be H5N1, but we can't afford to be complacent, and the costs are minimal at this point. I think we can safely say that the world will suffer another animal origin pandemic; every threat is an opportunity to prepare.
I truly understand the pressures on the livestock industry when people make intrusive demands for information that add little to readiness. But milk can be sold, animals can be moved once status is safe, and confidentiality is assured for those cooperating with reasonable testing requirements that aid in zoonotic preparedness.
I truly do appreciate your challenges to my thinking and hope my responses challenge your viewpoints. We all learn from each other. I better understand why many object to testing thanks to your interactions - that is invaluable to both me and my readers.
I appreciate the open discussion! I would disagree, though, with the point that the virus has already mutated to higher morbidity. What we are observing today is still a small sample, but the IFR from this sample is nowhere near what was reported from the H1N1 outbreak in the seventies. In fact, the observed IFR in the US so far is zero, thankfully. I also would not expect for morbidity to increase naturally. From the pathogen's perspective, it is a bad evolution strategy to evolve into a version that rapidly kills host species and thereby gives it far reduced opportunity to replicate and spread. Therefore, yes, we should be monitoring and conducting research on what the best strategy forward is, without overreacting.
Here is another thought experiment. Maybe even the culling of entire poultry flocks is an overreaction. Can't we run an academic experiment in a well-quarantined environment to investigate if there is any chance to build herd immunity?
Remind me, why are we doing this? Because cows produce less milk for a week, then recover? Because some dairy workers have a pink eye for a day, then recover? A PCR test alone has never been a conclusive diagnosis for acute illness and never will be. What this will accomplish, is that many false positives will be detected and herds will be placed under quarantine for no reason, putting further stress on the food supply chain... for no reason.
Pony Wisdom:
I truly appreciate your response! We need more dialogue among us on what I know is a very contentious topic for many in industry. Let me address several of your points one by one:
1) PCR is a very accurate diagnostic tool for acute infection; I agree that infection does not always equal illness; if often precedes illness, especially with viral diseases like influenza. So a bulk tank test may well become positive days before mastitis appears in the herd. But that doesn't mean that the cows aren't already infected and shedding lots of live virus into the milk supply. Pasteurization is our saving step at this point for the milk; however, workers milking the cows may be at the most risk for infection at this point because no one realizes yet that the cow(s) are shedding virus in the milk.
2) Your comment about some workers having pink eye for a day concerns me. Any viral illness, especially with an agent that is considered potentially a risk for further mutation towards zoonosis should never be minimized. First, pink eye can have serious secondary consequences. Second, pneumonia can also result with much more serious issues. Third, workers may have immune compromised loved ones at home - children, elderly, cancer patients, etc. at greater risk for secondary infections. These are exactly the people the CDC worries most about coming in contact with the virus. Unfortunately, it's the risk of human involvement that requires extraordinary measures for H5N1; we have no way around that.
3) Positive herds are not false positives (except in perhaps rare instances of sampling errors) and quarantines are placed only to protect other herds from exposure to the virus. Milk sales are not disrupted, only movement of livestock without approval during acute phases of illness. No responsible producer wants to give an infectious disease to another producer. Special needs for movement considerations can be negotiated with animal health officials.
4) Finally, we certainly agree about stress on the food supply chain! I'm extremely grateful that all of the safety protocols in place, especially pasteurization all ongoing marketing of safe milk products- I just enjoyed both a cheeseburger and ice cream for lunch.
I don't know if bulk milk testing will be ongoing, expanded to other states, or eventually replaced with other methodologies. however, I'm pretty confident that one way or another our public health officials will expect that we in agriculture continue to monitor the bovine virus for changes in the genetics, as well as protect our workers from exposure. Moreover, the poultry industry will insist on awareness of the risks they face from neighboring cattle operations. We live in a very interconnected world, even in agriculture - transparency is no longer an option.
Thanks again for your comments. I appreciate your willingness to express your frustrations.
John
I appreciate some of the arguments, but some other require second thoughts.
1) PCR tests can still return positive when illness has been cleared by all medical standards, as it reacts to virus fragments that may still linger in the recovered animal. This comes on top of the false positive rate for the test method itself, which is not zero and which I would like to see announced along with emergency measures.
2) The argument to "protect immune compromised loved ones at home - children, elderly, cancer patients, etc. at greater risk for secondary infections" is entirely moot. There is no known avian infuenza strain that spreads from humans to humans. Therefore, the most stringent measure to take is to make immunocompromised cattle workers wear PPE, if they don't already do so.
3) I appreciate the argument about not passing the virus on to another herd, but we need more information before we take extreme measures. I agree with your point about PSU: universities are the right place to develop a protocol commensurate with the danger. Based on the present set of observations, the danger from this virus is low, to animals and humans alike. Any statement I read that contains exaggerated danger involves some sort of an assumption that 'the virus will mutate to higher morbidity' and/or 'the virus will zoonotically jump to humans,' neither of which has ever happened. So let's cross that bridge when we get there. Which we won't.
Hello again Pony Wisdom:
You are right about "false positive" PCR's after active infection, when dead virus is still being shed. In fact, when weekly bulk tank sampling is first started in CO, it's possible that recovering dairy herds could test positive, then fairly quickly go negative with no clinical signs if the herd is recovering from infection and mastitis has either passed or was never a part of the clinical illness. So, if the herd never shows clinical illness, the bulk tank should be tested again, hopefully to clear the quarantine. I'd argue that the odds are high that the herd originally had the infection (but not full blown clinical illness, IF there wasn't a sample mix-up). It will be interesting to see how often herds are positive by PCR but show little or no mastitis; I was on a call this afternoon where participants discussed this. The point though is what I discussed in the earlier post - the herd is still infected (likely by respiratory means) but does not develop extensive mastitis. You can argue that is a non-dangerous event, and you have a point. There is much less virus shed, but still enough to trigger a PCR result on a bulk test. Animal movements would still be a threat to other herds, and the positive herd would be a (reduced) threat to workers and nearby poultry flocks.
Once bulk testing is in place and has a track record, new PCR results should indicate NEW infections, not resolving ones, i.e. a positive herd is likely just becoming positive and will become sicker, not recover.
As for your comments about the virus has not mutated to higher morbidity or made the jump to humans more easily, actually that has already happened NOW. The poultry workers are proof positive of that. I agree that the risk of onward transmission is still remote, but we now have some genomic tools to watch the changes in the virus. It is malpractice on our part NOT to do so. I wish we could be doing the same testing worldwide in all areas where H5N1 is raging, but this is one area we do have control.
We don't know which virus in which part of the world will make the jump - it may well NOT be H5N1, but we can't afford to be complacent, and the costs are minimal at this point. I think we can safely say that the world will suffer another animal origin pandemic; every threat is an opportunity to prepare.
I truly understand the pressures on the livestock industry when people make intrusive demands for information that add little to readiness. But milk can be sold, animals can be moved once status is safe, and confidentiality is assured for those cooperating with reasonable testing requirements that aid in zoonotic preparedness.
I truly do appreciate your challenges to my thinking and hope my responses challenge your viewpoints. We all learn from each other. I better understand why many object to testing thanks to your interactions - that is invaluable to both me and my readers.
Thank-you!
John
I appreciate the open discussion! I would disagree, though, with the point that the virus has already mutated to higher morbidity. What we are observing today is still a small sample, but the IFR from this sample is nowhere near what was reported from the H1N1 outbreak in the seventies. In fact, the observed IFR in the US so far is zero, thankfully. I also would not expect for morbidity to increase naturally. From the pathogen's perspective, it is a bad evolution strategy to evolve into a version that rapidly kills host species and thereby gives it far reduced opportunity to replicate and spread. Therefore, yes, we should be monitoring and conducting research on what the best strategy forward is, without overreacting.
Here is another thought experiment. Maybe even the culling of entire poultry flocks is an overreaction. Can't we run an academic experiment in a well-quarantined environment to investigate if there is any chance to build herd immunity?