The Los Angeles County Department of Public Health has released more information about recent cases of H5 influenza in cats, including links to raw milk exposure and potentially to raw meat diets. This expands on the information I wrote about yesterday regarding H5 influenza cases in California cats linked to recalled raw milk, and provides some important new information about cases in two separate households.

Household 1:

• Eight cats were fed raw milk that was subsequently recalled because of H5N1 flu contamination (because the milk came from an infected dairy and was not pasteurized). Seven of the cats got sick and five of them died. The other two are being isolated while they recover.
• Four cats were confirmed to have H5 influenza via PCR testing of samples from multiple body sites.
• The virus from the cats was sequenced and was the same as the virus from the recalled milk (and dairy cattle).
• Clinical signs in the cats were consistent with what we’ve seen so far in other infected cats (e.g. fever, lethargy, anorexia, respiratory distress ad neurological disease (mainly seizures)), but with more specific mention of a respiratory component in these cases.
• Viral shedding, both in terms of amount and time period, is hopefully being assessed in the surviving cats. That will be really valuable information to help with management of future cases.

Household 2:

• Five cats got sick after eating two different types of raw pet food, which contained poultry and beef. Both of these types of meat are potential flu sources if fed raw (because both chickens and cattle can be infected). Raw diet-associated fatal influenza has been previously reported in cats.
• Two of those cats were presented to a veterinary clinic in respiratory distress and were euthanized.
• Two other cats showed signs of lethargy, anorexia, neurological, respiratory and ocular disease. One of these cats was tested and was positive for H5 influenza. Further testing (and sequencing) of the virus will help infer the source.

Ideally, more testing of the surviving cats (from both households) will be done. That’s not a given since owners have to consent to further testing, and people have to be motivated enough to collect samples over time (which takes money, time and creates at least some degree of risk for people doing the sampling).

I’m spending a lot of time talking to veterinarians about how to flag potential H5N1 flu cases in pets coming into the clinic, both to help make a quick diagnosis and to help ensure any risk of further transmission from infected pets is contained. Our lack of understanding of the disease in cats is a big challenge, including the potential scope of illness, how common it is, and what the main risk factors are. This report from California actually helps a lot, as it provides more information about a broader range of clinical signs in cats, and once again raises the concern about the potential for exposure via raw pet diets.

The LA County Department of Public Health is recommending that veterinarians ask owners of sick pets about raw milk and raw diet exposure.

• That’s good advice all the time, and is particularly important now.
• I’d add a need to query outdoor access as a potential risk factor for exposure as well (both intended outdoor access (i.e. indoor-outdoor cats) or unintended access (i.e. indoor cat sneaking out)).

They are also recommending the use of appropriate PPE “when in contact with animals suspected or confirmed of being infected with H5 bird flu; acutely sick animals that have history of exposure to raw milk or raw milk products, wild birds or raw or undercooked animal products.”

• That’s good advice too. “Appropriate PPE” isn’t defined but I consider it to be a mask (ideally an N95 respirator or equivalent), gown and gloves, and eye / face protection (which often gets overlooked).

They don’t give a specific disease type to focus on in terms of screening cats for flu infection. That’s fair, because we just don’t know what to expect in all cases at this point. We know that flu sometimes kills cats showing signs of severe neurological and/or respiratory disease. We don’t know if some infected cats may have less severe signs, but we should approach it as if they can. So, cats with risk factors and non-specific disease should also be handled with care, at least for now.

They are also recommending flu vaccination of veterinary personnel. “Animal health staff are strongly recommended to receive their seasonal flu vaccine. Although this vaccine is not proven to prevent infection with H5 Bird Flu, it can help protect staff from seasonal human flu which is circulating right now.”

• That’s a good idea too. Seasonal flu vaccination may not do anything to protect against H5N1 infection, but may help to to avoid people getting infected with H5N1 and human seasonal flu at the same time. That helps to decrease the risk of H5N1 flu mixing with a human flu strain to make a new (and potentially nastier) strain that is more easily transmitted to and between people.

I suspect we’re going to learn a lot more about H5N1 in cats in the next few months, especially from California, where a state of emergency has been declared because of their poorly contained dairy cattle H5N1 flu situation.