Epidemiologic Notes and Reports Rash Illness
Associated with Gypsy Moth Caterpillars -- Pennsylvania
Between the end of April and the third week of May 1981, an
increase in rash illness was reported by 2 schools in Luzerne
County,
in northeast Pennsylvania. School A had an enrollment of 320
students, with 135 affected by rashes (an attack rate of 42.2%).
School B had 76 out of 300 students affected (an attack rate of
25.3%). The symptoms included pruritic rash and occasional
urticaria. Fever, nausea, vomiting, diarrhea, and chills were
seldom
reported. The rash was generally located on exposed areas of the
body--75.4% on arms, 22.8% on the neck, and 21.1% on legs. Rash
was
less often observed on the back, stomach, face, chest, or hands.
The
median duration of the rash for school A was 7 days, and for school
B,
4 days. All skin scrapings of the rash for bacteria were negative;
throat and stool cultures, and tests of acute- and
convalescent-phase
serum specimens to detect viruses were also negative.
A group of well students from the same schools were selected as
controls. All students were interviewed for history of outdoor
exposure. Touching caterpillars (p 0.01), working in a garden (p
0.05), and going fishing (p 0.01) were statistically associated
with
rash illness, whereas a history of allergies was not.
Of the cases with known dates of onset, 27.5% occurred during
the
first week of May. This period coincides with the first larval
instar
of gypsy moth caterpillars, which occurs between the first and
fourth
weeks of May in this area. No new cases were reported after the
third
week of May. School A is located in a heavily wooded rural area,
and
school B in a small town with many trees. A distribution map of
gypsy
moth location indicates highest concentration in the areas in which
these schools are located.
The temporal and geographic association between the outbreak of
rash illness and the prevalence of gypsy moth larvae suggest a
causal
relationship may exist.
Reported by R Aber, MD, Hershey Medical Center, T DeMelfi, T Gill,
B
Healey, MPA, MA McCarthy, RN, N Oswell, W Ruhig, H Speziale, RN, EJ
Witte, VMD, State Epidemiologist, Pennsylvania Dept of Health.
Editorial Note
Editorial Note: Skin diseases resulting from contact with members
of
the Order Lepidoptera were described in ancient Greek medical
writings. In 1901, several U.S. patients were reported to have
experienced dermatitis following contact with Euproctis chrysorrha
(brown-tailed moth) larvae (1). Several outbreaks of dermatitis
caused by Lepidoptera have been reported; the largest outbreak
involved 600 cases among 6,000 soldiers in Israel (2,5). Clinical
symptoms and signs are quite variable depending on the type of
insect
and its stage of development when encountered, the intensity and
duration of exposure, the pathogenetic mechanism involved, and the
susceptibility of the host. Disease is usually caused by direct
contact with the insect or its parts, but indirect contact and
airborne transmission have been documented. At least 3
pathogenetic
mechanisms have been described: l) intracutaneous injection of
toxic
substance(s) through hollow appendages (setae) of the insect, 2)
direct irritant effects of insect hairs or appendages, and 3)
hypersensitivity reaction to insect antigen. A biphasic reaction
to
skin testing with insect antigens has been described among some
patients, which may represent sequential occurrence of 2 or more of
these mechanisms (6).
The gypsy moth (Lymantria dispar) is a serious threat to
hardwood
trees in the northeastern United States (7). It was introduced
into
the Boston area in 1869 and has been spreading concentrically.
Despite heavy infestation in the Northeast, skin diseases have
seldom
been attributed to the insect except in special laboratories where
staff work with the moth and its larvae. No community outbreaks
had
been reported before 1981, when outbreaks of skin disease
attributed
to the gypsy moth were reported from Connecticut, Massachusetts
(8),
Rhode Island (9), and Pennsylvania. These outbreaks are believed
to
have been caused by contact with early larval stages of the moth,
which are highly mobile and airborne. It is also possible that the
disease is caused by a chemical substance that the larvae acquire
during pest control programs. Primary-care physicians and
dermatologists should be aware of skin disease resulting from
contact
with gypsy moth larvae.
References
White JC. Dermatitis produced by a caterpillar. Boston Med
Surg
J 1901;144:599.
Hillier FF, Warm RP. Caterpillar dermatitis. Brit Med J
1967;1:346-8.
McGovern JP, Barkin GD, McElhenney TR, Wende R. Megalopyge
opercularis. Observations of its life history, natural history
of
its sting in man, and report of an epidemic. JAMA
1961;175:1155-8.
Hill WR, Rubenstein AD, Kovacs J Jr. Dermatitis resulting from
contact with moths (Genus Hylesia). JAMA 1948;138:737-40.
Ziprkowski L, Hofski E, Tahori AS. Caterpillar dermatitis.
Israel Med J 1959;18:26-31.
Goldman L, Sawyer F, Levine A, Goldman J, Goldman S, Spinanger
J.
Investigative studies of skin irritations from caterpillars. J
Invest Derm 1960;34:67-9.
Pennsylvania Department of Environmental Resources. The gypsy
moth. Harrisburg, Pa. December, 1980 (revision).
Northeastern Forest Experiment Station News. USDA Forest Serv,
May
1981.
Rhode Island Disease Bulletin. Caterpillar-associated rashes
in
Northwest Rhode Island. 1981;18.
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