Epidemiologic Survey on Outbreak of Dermatosis Associated with Ants, Pachycondyla chinensis

Bae, Geun Ryang; Lim, Hyun Sul; Kim, Byung Jin

Abstract

OBJECTIVES
An outbreak of dermatosis occurred at a city gas manufacturing factory in Pohang in Aug, 1998. The authors conducted a study to find the cause and prevent the dermatosis.
METHODS
We conducted a questionnaire survey of 73 workers in the factory twice, once on Aug. 14th and then Sept. 11th, 1998. Also, a dermatologist examined their skin lesions. We suspected ants as the cause, so we collected them for identification.
RESULTS
Twelve cases of dermatosis were identified with an attack rate of 16.4%. The attack rates were not different by age, educational level or tenures. The attack rates were 66.6% among production workers, 2.0% among clerical workers, 16.7% among tank trailer drivers and 0% among guards. The attack rate among production workers was significantly higher than that of the others (p<0.01). There were no histories of the same dermatosis for the past one year. Histories of other skin diseases and allergies were very rare in both cases with skin diseases and control. Multiple, pruritic, rice-grained to bean sized erythematous macules or papules with a central biting point could be found after initial severe itching occurred. Three cases showed signs of dermatosis with an allergic nature. The onset of dermatosis was between July 30 and Aug 12 and the durations varied from 5 days to over a month. The most frequent sites of skin lesions were the chest and abdomen (66.6%), and they were also observed on the neck (33.3%), arms (33.3%), shoulders (16.7%) and back (16.7%). Over 10 ants with their wings were collected in the work place and identified as Pachycondyla chinensis, subfamily Ponerinae.
CONCLUSIONS
We thought that the outbreak of dermatosis was brought about by the ants flying into the work place through the open windows. Further studies on the factors contributing to the prosperity of the ants in this area are needed.