Thursday, September 15, 2011

Hypersensitivity Pneumonitis - September ILD Meeting


This month’s meeting featured Dr. Paul Blanc, Chief of Occupational and Environmental Medicine. He is conducting a first of its kind study on Hypersensitivity Pneumonitis. It includes a questionnaire, a lung function test, a home inspection for dust samples and blood tests.  There has never been a systematic evaluation of people’s homes or even a questionnaire involved in any other study. When putting together the questionnaire, he contacted the National Jewish Hospital, who is an expert of HP, to ask for their questionnaire to use as a guide. He discovered that even they have not done a complete study of patients who have this disease.

He has completed that part of the study and has sent the dust and blood samples off to a lab in Sweden. Apparently, there are no labs in the US who test for a variety of antigens against a blood sample.

He did say that HP’s hallmark is that for some reason a sensitization to something happens then once sensitized, it continues.

Dr. Blanc went through part of the questionnaire with us, which studies different possible exposures in the workplace and at home. In the workplace, here are some known exposures, which have caused HP:
Epoxy, two-part glues or cements, super glue, acrylate or hot melt glue
Urethane, polyurethane or iso-cyante
Pharmaceutical products
Pyrethrun or other pesticides
Hay, silage, straw or agricultural waste
Saw dust, tree bark or other wood dust
Other plants or natural fiber dusts
Compost, waste processing or sewage
Animal hairs, dander, fur or animal waste
Bird feathers, down or other bird-related materials
Sea shells or mother-of-pearl
Water humidification systems
Indoor fountains, water features or other water sprays
A swamp or desert cooler for air conditioning
Moldy conditions or water-damaged workplace
Metal cooling or cutting fluids
Metal dust or fumes, including from welding
Sand, silica, quartz, diatomaceous earth or stone or concrete dust

In the home, the questionnaire focused on water features, water collection systems, feather bedding or goose pillow, comforters or duvets, a “Sleep Number” or “Select Comfort” bed and tatami mats. They also included questions about water damage, mold or mildew, carpets laid over cement and indoor pesticide applications. He also said that if any mold is on drywall, the drywall must be removed. It cannot be cleaned.

Also in the home section, there were questions about pets but the focus was on large birds. There were questions regarding outside birds roosting on the roof or bird droppings on the exterior of the home or even if there were regular fly-overs or migrations by flocks of birds. Hot tubs also seem to be an issue and several question dealt with them.

The first time HP was mentioned in Medical Journals was 1932 and the two cases cited that year were Maple Bark Strippers Lung and Farmer’s Lung.

What is HP? It is a lung disease “allergic” process that brings on an immune related response or “sensitization.” Continued exposure to this antigen makes the disease worse. HP is NOT due to the same types of allergies like hay fever or cats, for example. How to know the difference? An allergy to cats would exhibit immediate symptoms. A reaction to an allergen, which develops into HP, has no immediate reaction.

This is also the one and only lung disease that will not be contracted if one is a smoker. Something in the cigarettes nullifies the antigen.

Causes of HP? Inhalation, a biopsy has distinctive chest CT and Blood Antibodies test. It is caused by fungi/bacteria, animal derived substances, exposure to synthetic organic dusts, chemicals used in industrial settings and exposure to selected pharmaceuticals.

But, there are caveats to the above, instead of inhalation it can be caused by medications,  a biopsy can be non-specific, the CT in advanced disease can look like ILD, the blood tests only work if the doctor knows what to check for which is rare.

It was interesting to learn where a group of people got HP:
Agriculture – Livestock – 24
Agriculture – crops – 18
At home – 10
Construction – 3.3
Trucking – 3.3
Hospital – 3.3
Yarn and Fabric factories – 2.5
Elementary and secondary school – 1.6
There were other listed but the numbers were very small and I did not copy them from the presentation.

Common causes of HP are:
Farmer’s Lung from moldy hay, Bird Handler’s Lung from bird droppings and feathers, Lab Worker’s Lung from rat urine, Ventilator Lung from humidifiers and dehumidifiers, Cork Workers Lung from mold, Mushroom Worker’s Lung mostly in Japan, also hot tubs.

Dr. Blanc then showed a chart culled from information on death certificates. Of the 64 death certificates, the following died of:
Avian Antigens – 29
Hot Tub Disease – 18
Farmer’s Lung – 9
Household exposure – 8
Heavy indoor mold – 4
Could not get a positive in history or serologic testing – 21

How common is HP? It is rare. Very rare. Dr. Blanc showed us a graph of deaths relating to HP. I copied just a few of the numbers:
1991- 36
1996 – 51
1997 – 38
1998 – 57
Again, that is for the entire US.

It was even more interesting to discover the states with the highest number of HP deaths: They were mostly agricultural states with a high number of dairy farms. It included Idaho, Colorado, North and South Dakota, Iowa and Wisconsin.

Can HP be cured?
  1. Consider HP in a diagnosis and try to identify the exposure then remove person from the exposure.
  2. Immune modulation – steroids
  3. Lung transplantation. There has be only one case at this university hospital where someone re-contracted HP post transplant. 

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