H E el Bushra1, A A Bin Saeed. 1. Saudi Arabian Field Epidemiology Training Program Riyadh, Kingdom of Saudi Arabia.
Abstract
OBJECTIVE: To identify the factors that influence transmission of bacillary dysentry (BD) within families during a propagated outbreak of bacillary dysentery. DESIGN: A retrospective cohort study. SETTING: Eighteen neighbouring villages in rural Gizan, southwestern Saudi Arabia. SUBJECTS: Two hundred and thirty three cases of BD were identified among seventy nine families. RESULTS: Secondary cases of BD occurred in 57 of 79 families with a primary case of BD. The secondary attack rate per cent (AR%) within families ranged between 7.7% and 80%. Age of primary cases did not correlate with degree of secondary AR% in exposed families (p > 0.04; p > 0.05); however, within households, the age of the first secondary cases (median = two years) was usually less than the age of the primary case (median = six years). Children under five years of age constituted 43% of secondary cases. The median interval between successive cases within a house ranged from three and seven days. Two hundred and twenty cases (94.4%) gave history of close contact within another case of BD. Cases of BD were exposed to close relatives with BD (79.1%), neighbours (11.4%), and friends (9.5%). Risk factors influencing the spread of BD within families included two rooms or fewer per house (OR = 4.3, 9.5% CI 1.3-14.3), family size of five or more (p = 0.012, two-tailed Fisher's exact test), and presence of more than two persons per room (OR = 11.2, 95% CI 3.1-42.4). CONCLUSION: Person-to-person secondary transmission can amplify the spread of bacillary dysentery within households and neighbouring villages. Crowding was a risk factor that amplified transmission of BD within families.
OBJECTIVE: To identify the factors that influence transmission of bacillary dysentry (BD) within families during a propagated outbreak of bacillary dysentery. DESIGN: A retrospective cohort study. SETTING: Eighteen neighbouring villages in rural Gizan, southwestern Saudi Arabia. SUBJECTS: Two hundred and thirty three cases of BD were identified among seventy nine families. RESULTS: Secondary cases of BD occurred in 57 of 79 families with a primary case of BD. The secondary attack rate per cent (AR%) within families ranged between 7.7% and 80%. Age of primary cases did not correlate with degree of secondary AR% in exposed families (p > 0.04; p > 0.05); however, within households, the age of the first secondary cases (median = two years) was usually less than the age of the primary case (median = six years). Children under five years of age constituted 43% of secondary cases. The median interval between successive cases within a house ranged from three and seven days. Two hundred and twenty cases (94.4%) gave history of close contact within another case of BD. Cases of BD were exposed to close relatives with BD (79.1%), neighbours (11.4%), and friends (9.5%). Risk factors influencing the spread of BD within families included two rooms or fewer per house (OR = 4.3, 9.5% CI 1.3-14.3), family size of five or more (p = 0.012, two-tailed Fisher's exact test), and presence of more than two persons per room (OR = 11.2, 95% CI 3.1-42.4). CONCLUSION:Person-to-person secondary transmission can amplify the spread of bacillary dysentery within households and neighbouring villages. Crowding was a risk factor that amplified transmission of BD within families.
Authors: A I Khan; K A Talukder; S Huq; D Mondal; M A Malek; D K Dutta; G B Nair; A S G Faruque Journal: Epidemiol Infect Date: 2005-11-17 Impact factor: 2.451