A Study of the Efficacy of Doxycycline Prophylaxis to Prevent Infectibility of Leptospirosis among Populations Who Were Affected by Flooding Disaster in Nan Province, Thailand, June - August 2011

Abstract

Background: Leptospirosis was one of a major public health problem. Data situation in Thailand showed 4,944 cases, morbidity rate were 7.76 per 100,000 populations and mortality rate were 0.09 per 100,000 populations in 2010. Most of leptospirosis cases were found after flooded. In 2011, there were two big flooded of the decade in Nan province in June and August. The worst affected area were in Tha Wang Pha, Pua, Tungchang, Chiang Klang, Phu Piang, Muang and Wiangsa districts; Populations resided around 396,612 were affected by outbreaks of leptospirosis. A morbidity rate was increased from 2 to 14.2 cases per 100,000 populations. Some of affected populations took 200 mg of doxycycline orally as a prophylaxis dose. None of the mentioned study have never been implemented in the area.
Methodology and results: An unmatched case control study with a ratio of case and control at 1:2 was conducted to evaluate an effective of doxycycline prophylaxis to prevent infectibility of leptospirosis and/or minimized severity of the illness. Inclusion criteria included 1) persons who were affected by the flooding or persons rescuing the victims from the flood in 7 districts of Nan Province 2) aged between 12 - 70 and 3) no history of any underlying disease. There were 152 eligible participants. A ratio of male to female was 1.3 to 1. Among of those 50 from 152 participants, had taken 200 mg of doxycycline orally once each week. Mean of age among group of taking doxycycline orally as a prophylaxis, was 45 years and 48 years among the persons without taking doxycycline. Most of leptospirosis cases were agriculturist (86.57%). Fever, headache, muscle ache and severe pain at thighs were dominant signs at 73.3%, 71.1%, 64.5% and 47.5% respectively. There was no different significantly for infectibility prevention of leptospirosis between persons with and without taking doxycycline prophylaxis (Odds ratio [OR] = 1.34, 95% CI 0.23 - 5.32). While the non - taking doxycycline group showed more severity of illness than the persons who took oral doxycycline prophylaxis (OR = 2.33, 95% CI 1.71 - 20.47).
Conclusions: Taking doxycycline orally as a leptospirosis prophylaxis could not prevent the infectibility, but it could minimize the severity of the illness in Nan province. Therefore, people who were affected by floods and rescuing victims should be considered for the use of 200 mg doxycycline orally for prophylaxis once each week for three weeks to prevent complications thereafter.