Thinking about Swine Flu in the Peanut Gallery

A few thoughts about our most recent emerging infection with apologies for anthropomorphism and speculation to follow... Influenza viruses evolve/mutate pretty quickly and practice a type of "free love" exchanging genetic material (RNA in this case) usually when 2 strains are in an (usually non-human) individual at the same time. These may have been part of the back-story of the strain (or strains) of influenza currently dominating the news cycle. At least some of the recent ancestral strains seem to have come from pigs, hence the Swine Flu moniker. As with any emerging infection, there are many unknowns. It seems to me that 2 particularly relevant matters are immunity (or lack thereof) and virulence. It may be that this virus's genes and the resulting proteins are sufficiently different from previous strains as to render them unrecognizable to out immune systems. Then there is "original antigenic sin"; I don't know if this is a factor in this case, but I couldn't resist mentioning it. Virulence--how likely this flu is to cause serious illness or death--is still an open question although the preliminary reports from outside of Mexico are not alarming. (Even in Mexico, since we don't actually know the denominator...) Which Influenza A are you anyway? The current swine flu is an Influenza A H1N1, a quite different virus (immunologically speaking) from the seasonal human Influenza A which is still around as well. The classification and naming of influenza viruses can be confusing. I found a really nice easy-to-read article at arstechnica.com. Is it time to panic yet? In a word, no. (Although all those exhortations to remain calm may not be helping...) The new swine flu is sensitive to several anti-viral medications. Hand-washing, respiratory hygiene and other avoidance measures have significant roles to play in preventing the spread of infection. Interim guidelines have been posted by the CDC (cdc.gov--the link is on the home page) and are updated regularly. This is my preferred source of information and I highly recommend it.

Allergy and the First Pet

Like many of our fellow Americans, I have been avidly following the stories of the Obama family’s search for a dog. As an Allergist who often fields questions about “hypoallergenic” dogs, these reports have been of particular interest. Generally speaking, having a dog when allergic to dogs is a good news-bad news (bad news-good news?) situation. The bad news is that a hypoallergenic breed has not yet been found (more about this later). The good news is that dog allergy doesn’t necessarily bar one from having a dog. People who are allergic to dogs react to proteins found in the skin flakes and saliva. There are several known proteins from dogs that cause allergies (allergens) and others probably exist. The amount of protein (allergen) varies among individual dogs. A person with allergies to dogs may have more symptoms with one dog and fewer symptoms with another but this cannot be predicted based on the breed alone. I have not seen any studies of allergen levels of Portuguese Water Dogs. One study I do know of looked at levels of one of the major dog allergens across a number of breeds—including German Shepherds, Poodles, Cocker Spaniels, Labradors and a few others—and found that only the Labradors had an average allergen level that was statistically significantly lower than the others. But, before everyone runs out to get a Lab, it’s important to realize that the range of even the Labs overlapped quite a bit with the other breeds. (Ramadour et al. 2005. Allergy (60)8:1060-4—a link to the full text article can be found at pubmed.gov). In summary, there is more variation between individual dogs than between breeds. So, what to do if you’re allergic to dogs and really want one as a pet? In part the answer lies in how affected the person in question is (e.g. mildly itchy eyes vs. being hospitalized for asthma). For some people choosing another type of pet is probably the best way to go. Also, spending time with an individual dog prior to deciding to adopt it may give you an idea if that dog triggers allergy symptoms (although the environment in which these visits take place can be a confounding factor). For dogs that are already part of the family, there are measures to decrease exposure to the allergen (environmental controls): hand washing after petting; washing the dog weekly; washing the dog’s bedding in hot water weekly; using a vacuum cleaner with a HEPA filter and wearing an appropriate mask; and having a “dog-free” zone at home that includes bedrooms, carpeted areas and upholstered furniture (especially the bedroom). (ACAAI.ORG has tips for many environmental controls; look for the Allergy HOME link under patient education.) Nasal saline washes (for nasal and sinus symptoms), medications and allergen immunotherapy are some of the therapy options for the allergic dog lover. (AAAAI.ORG has drug guides for allergy and asthma medications; decisions about which medications are right for you are best made with your doctor.) One of the most important steps is to get a correct diagnosis, which isn’t always possible from history alone. Allergist-Immunologists (or Allergists for short) are physicians specifically trained to diagnose (including choosing the right tests and interpreting the results) and treat allergies including allergic asthma. (Find out more about Allergists at AAAAI.ORG and ACAAI.ORG). Many people with allergies can lead healthy active lives with symptoms controlled by the right combination of strategies and treatments. As for the Obama family and the new First Dog, may they have many good years together and may Malia’s allergies be well controlled. (Note: I have no first hand information about Malia’s allergies, just what I’ve seen on the news.) Although this is a post about dogs, it is spring and I wish everyone a happy, healthy (symptom-free) season. (Disclaimer: this blog is for informational purposes only and should not be used in place of a physician’s evaluation and care.) Copyright 2009 Rebecca G. Piltch, M.D.