Healthy Homes and the Allergist/Immunologist - Twitter summary from 2014 #ACAAI meeting

Environmental Assessment and Exposure Control

Dr. Jay Portnoy presented an Overview of Environmental Assessment and Exposure Control.

What are molds? They are in the fungi Kingdom - over 1,500,000 species. Fungi are composed of cells that form a hypha, grow in sexual and asexual stages - asexual spore grow out of a conidium. Sexual spores form an ascus (sack). The term fungi imperfecti is outdated.

Taxonomy of molds is complex but important - hypersensitivity clumps together within phyla e.g. mucor and rhizopus are usually cross-reactive. The extensive cross-reactivity within phylogenetic classes allows us to skin test to just one fungal species within each phyla.

Dr Portnoy's study of 2001 showed that the laundry room, bathrooms and basements had the most mold spores - because they are damp, and cleaned less often.

If mold spores found inside the home correlate well with outdoors species in the area, they are highly likely to be non-pathologic.

189 different fungal species produce allergens, in 62 protein families, approximately 132 allergens. Peroxisomal membrane proteins, acid ribosomal proteins, cyclophilins - all cross react within each class extensively. Other fungal metagolites include ergosterol (used to measure fungal biomass), beta 1-3D glucan - cell wall component, and mycotoxins.

How does mold cause respiratory symptoms?

Fungal beta 1-3-D glucan can cause respiratory disorders without IgE sensitization. Larger amounts of beta 1-3-D glucan are associated with higher degrees of symptoms - Dr Portnoy emphasized that there was no proof of causation however.

Pekkanen study in 2007 - mold growth in home correlated with asthma symptoms as did the degree of humidity/dampness. Fungal secondary metabolites as harmful indoor air contaminants: 10 years on.

Skin testing with molds

The fungal extracts for skin testing are not standardized and are highly variable - this leads to challenges in diagnosis. Which fungi to test for? Most commonly positive SPT are to Alternaria and Candida. However, a positive skin test to Candida is just a marker for fungal sensitivity, it does NOT cause clinical disease. Dr Portnoy proposed panel for fungal sensitivity screening - alternaria, cladosporium, aspergillus, penicillium, candida and trychophyton. If the patients aren't allergic to any of the fungi above, it is highly unlikely to find positive tests to any other species - can stop further testing.

Minimizing mold in the home requires water control - dehumidification is key, remove/discard moldy items (ie. carpets, wallboard), exhaust vents.

Practice parameters for environmental contaminants

W. Phipatanakul discussed Practice parameters for environmental contaminants. The furry animals practice parameter - cat, dog mice, rabbits, horse and cow antigen are clearly in home dust and air. Hamster is less likely.

Cat allergen

Cat allergen in home declines slowly after pet removal - it takes 6 months to eradicate Fel D 1 once you remove the cat. Effects of cat washing - Class B evidence - it does significantly reduce allergen level but it only lasts 1 week.

Dog allergens

"Hypoallergenic dogs" - allergen levels in the homes with 'hypoallergenic breeds' are identical to those families who own 'regular' dogs. "Hypoallergenic dogs are a Tall Tail".

Dust mite allergens

First line for dust mite control - Class B evidence for mattress and pillow covers, wash bedding and control humidity to 35-40%. Environmental assessment and exposure control of dust mites: a practice parameter

HEPA Air filters reduce particulate matter especially in smoke exposed home, one study showed decreased asthma ER visits for kids.

Dust mite avoidance (click to enlarge the image).

Mouse and cockroach allergens

Home cockroach allergen exposure is clearly associated with asthma morbidity in inner city children. Mouse allergen is also showing a strong signal for worsening asthma control in inner city children. Dr Phipatanakul reminded audience that school environment is equally important for children - dog, cat and mouse allergen are found in schools too. Dr Phipatanakul makes plea to think of the "occupational" exposures for children i.e. the schools when you evaluate kids with allergies.

Re-mediating homes and schools of mouse and cockroach is challenging - it requires multi-pronged approach of integrated pest management.

Nocturnal temperature controlled laminar flow devices may prove helpful in future:

Provider-Facilitated Home Assessments

Dr Kevin Kennedy discussed Provider-Facilitated Home Assessments: Expanding care through preventive practice.

What are patients actually willing to do for environmental control? Most are willing to obtain covers for pillow/mattress, and wash bedding. In a post education intervention, 70% of patients obtained DM covers and increased bedding washing, only 30% vacuumed more frequently.

Beware of reports from "Sick Home Investigators" - they often do just a tape lift of dust samples that are put through fungal culture.

This is a Twitter summary from 2014 #ACAAI meeting. The post is a part of series. See the rest here:

The Twitter summary was made possible by @DrAnneEllis and @MatthewBowdish

Several allergists did a great job posting updates from the 2014 meeting of the #ACAAI. I used the website “All My Tweets” to review the tweets. For comparison, here are the tweets from previous #ACAAI meetings (scroll down the page for the past years):

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