Risk factors associated with leptospirosis during an outbreak in Middle Andaman, India

Area of Science:

• Epidemiology
• Infectious Diseases
• Public Health

Background:

• Leptospirosis outbreaks are common in North and South Andaman Islands, but a 2002 outbreak in Middle Andaman was the first.
• Previous risk factor studies used seropositivity, which may not indicate current infection.
• No prior risk factor studies were conducted in Middle Andaman during an outbreak.

Purpose of the Study:

• To identify environmental, occupational, and behavioral risk factors for leptospirosis during the 2002 Middle Andaman outbreak.
• To understand the transmission dynamics of leptospirosis in a novel outbreak setting.
• To inform targeted public health interventions for leptospirosis prevention.

Main Methods:

• A case-control study was conducted during an October-November 2002 leptospirosis outbreak in Rangat, Middle Andaman.
• Leptospirosis cases (n=52) were confirmed using microscopic agglutination test (MAT) with rising paired sera titers.
• 104 seronegative controls, matched for age, sex, and neighborhood, were compared against cases using conditional multiple regression and stratified analysis.

Main Results:

• Significant risk factors identified included cattle presence at home, drinking stream water, garbage contact, walking barefoot, and standing in water during work.
• A dose-response relationship was observed between the number of cattle at home and leptospiral infection risk.
• Cattle were suggested as a potential source of infection, highlighting specific transmission pathways.

Conclusions:

• Environmental and occupational factors, particularly cattle proximity, are significant risk factors for leptospirosis in Middle Andaman.
• Understanding these risk factors is crucial for developing effective public health strategies to control leptospirosis transmission.
• The findings provide insights into the disease's transmission dynamics, enabling targeted interventions.