[An epidemic outbreak with respiratory symptoms in the province of Almeria [Spain] due to toxic microalgae exposure].

AIM: To describe an outbreak with symptoms of respiratory tract irritation reported in a village located on the Almerian coast in August 2006, as well as the etiological research performed.

METHODS

We performed a descriptive case-control study. The village was divided into three areas (from 1 to 3) according to the distance from the sea. Symptomatology was subjectively assessed on an ascending severity scale (from 1 to 3). Attack rates (AR) were estimated. To correlate symptom severity by areas and type of exposure, odds ratios (OR) with 95% confidence intervals were estimated. The chi-square test and Fisher's exact test were used. Environmental research was performed.

RESULTS

Fifty-seven cases and 26 controls were surveyed. An AR of 69% was estimated. The most frequent symptom was sneezing (87.7%). Residents in area 1 had a higher risk of more severe symptoms than those in area 3 (OR = 46.7; 95%CI: 4.7-2,067.4). Residents who reported having spent more time outside had a higher risk of more severe symptoms (OR = 12.2; 95%CI: 1.1-615.1). A concentration of dinoflagellates Ostreopsis of 1200 cells/l was determined in sea water.

CONCLUSIONS

An outbreak with respiratory symptoms and with differing severity depending on the distance of housing from the sea occurred. According to the environmental and epidemiological research, the symptoms were probably related to the presence of Ostreopsis toxic microalgae.