Summary
Objectives: To assess the potential risk factors for shigellosis including housefly density.
Methods: A matched case-control study to investigate potential risk factors for shigellosis was
conducted in a semi-urban area, Kaengkhoi District, Saraburi Province, central Thailand. Shigella
cases were ascertained from a two-year population-based surveillance study detecting diarrhea
and shigellosis in the area. The study evaluated a wide range of exposures, which were assessed
by odds ratios (OR) adjusted for proxy markers of socioeconomic status: family income, and type
of residence, using conditional logistic regression analysis.
Results: Hygiene behaviors such as regular hand washing ( p < 0.05), a clean environment
surrounding the household ( p < 0.001), and the availability of water to flush the toilet
( p = 0.08) were associated with a reduced risk for shigellosis in the multivariate model. In
contrast factors indicating a lower than average socioeconomic status, such as having to rent
instead of owning one’s housing ( p < 0.001) and a low family income ( p < 0.01) were associated
with an increased risk for shigellosis. For children, breastfeeding showed a strong protective
effect in reducing the risk of shigellosis ( p < 0.01). Prior to adjustment for environmental
factors, fly density in the kitchen area was associated with an increased risk of shigellosis
( p < 0.01).
Conclusions: We found a correlation between socioeconomic status and the risk for shigellosis. To
reduce shigellosis in this setting, we recommend interventions focused on three aspects:
improved water supply and sanitation (especially latrines and garbage disposal) including fly
control, health education on hand washing, and the promotion of breastfeeding.
# 2006 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights
reserved.