Current Health Problems - SWEDEN

Allergic symptoms due to the Pine Processionary Moth (Thametropoea pinivora) in Gotland,

Sweden.

By: Sandra Kapoun, General Medicine

What is the problem?● On the southmost part of the island of Gotland, on the east coast of Sweden, there lives a species of Pine Processionary Moth. They

have been causing health problems in natives & tourists.

● Thametropoea pinivora

Thametropoea pinivora● The moth is present in pine forests located in a restricted area of the most southern part of the island.

● The density of the population has increased considerably during the last few years.

Localisation & Spread● Areas of RED : high density● Areas of YELLOW : low

density● Areas of GREEN : no

colonies found● Areas of GREY : no pine

forest

● Note: this moth-type is normally found in the Mediterranean area.

Biology & Development● The larvae produce and release microscopical lancettlike allergenic hairs (setae) during their late stages:

● → the hairs are only 0.1mm long

● → they are arranged in rows on the larvae's back

● → each larvae has 1000-2000 such setae.

● → each setae has multiple 'hooks' which facilitate adhesion to object/skin/clothes

● → the hairs are spread through air like pollen

● → the hairs are active for several months

Pathogenesis & Symptomatology

● Individuals exposed to airborn hairs/direct-contact hairs from larvae, develop symptoms:

● → skin reactions (95%): itchy maculopapular rash on FACE, NECK, HANDS

● → airway reactions (10%): swelling + discomfort, rhinitis, asthmatic reactions

● → other: fever, anaphylactic reaction (rare but serious)

● → Reactions are caused by IgE-mediated immunity.

● In light of the pathogenesis, there have also been theories that the setae contain poisonous substances:

●→ scientists theorise that substances in the larvae hair cause release of histamine from mast cells, producing allergic symptoms not associated with the IgE-mediated immune reaction.

● → This theory has been supported by animal testing procedures.

An interesting TWIST...● There is a largely varying symptomatology in patients: only ca.

10% of patients have IgE-Abs against larvae Ag.● → one possibility:

→ certain individuals are more predisposed to hypersensitivity to CHITIN (= a primary building block in insect skeleton & setae)

→ there seems to be a connection between inflammatory asthma-like airway symptoms & inability to break down chitin.

In Conclusion..● As discovered, the Pine Processionary Moth has been a very important & unknown cause of allergic symptoms of the skin and mucus

membranes in the population of Sweden (Gotland is visited by a large % of the population in the summer months).

● Treatment comprises standard alleviation of allergic symptoms, and steering clear of moth-infested areas.

BIBLIOGRAPHY● http://www.lakartidningen.se/engine.php?articleId=4533● http://en.wikipedia.org/wiki/Pine_Processionary● http://www.lakartidningen.se/engine.php?articleId=12360