Human Leptospirosis Infection in Fiji: An Eco-epidemiological Approach to Identifying Risk Factors and Environmental Drivers for Transmission

Abstract

Leptospirosis is an important zoonotic disease in the Pacific Islands. In Fiji, two successive cyclones and severe flooding in 2012 resulted in outbreaks with 576 reported cases and 7% case-fatality. We conducted a cross-sectional seroprevalence study and used an eco-epidemiological approach to characterize risk factors and drivers for human leptospirosis infection in Fiji, and aimed to provide an evidence base for improving the effectiveness of public health mitigation and intervention strategies. Antibodies indicative of previous or recent infection were found in 19.4% of 2152 participants (81 communities on the 3 main islands). Questionnaires and geographic information systems data were used to assess variables related to demographics, individual behaviour, contact with animals, socioeconomics, living conditions, land use, and the natural environment. On multivariable logistic regression analysis, variables associated with the presence of Leptospira antibodies included male gender (OR 1.55), iTaukei ethnicity (OR 3.51), living in villages (OR 1.64), lack of treated water at home (OR 1.52), working outdoors (1.64), living in rural areas (OR 1.43), high poverty rate (OR 1.74), living <100m from a major river (OR 1.41), pigs in the community (OR 1.54), high cattle density in the district (OR 1.04 per head/sqkm), and high maximum rainfall in the wettest month (OR 1.003 per mm). Risk factors and drivers for human leptospirosis infection in Fiji are complex and multifactorial, with environmental factors playing crucial roles. With global climate change, severe weather events and flooding are expected to intensify in the South Pacific. Population growth could also lead to more intensive livestock farming; and urbanization in developing countries is often associated with urban and peri-urban slums where diseases of poverty proliferate. Climate change, flooding, population growth, urbanization, poverty and agricultural intensification are important drivers of zoonotic disease transmission; these factors may independently, or potentially synergistically, lead to enhanced leptospirosis transmission in Fiji and other similar settings.

Role of Environmental Factors in Shaping Spatial Distribution ofSalmonella entericaSerovar Typhi, Fiji

“…Similar to our findings, other studies have found positive associations between diseases transmitted by the fecal–oral route (such as cholera and typhoid) and waterborne diseases (such as leptospirosis) with heavy rainfall and proximity to major rivers ( 36 – 40 ). Heavy rains in Fiji, particularly during the cyclone season (November–April) ( 21 ), might lead to overflowing of septic tanks and contamination of the local environment and drinking water sources.…”

“…Fiji had outbreaks of typhoid fever and leptospirosis after devastation and flooding caused by cyclones ( 16 , 18 , 40 , 43 ). Our multivariate model demonstrated an increased risk for Salmonella Typhi infection for persons living closer to the modeled flooding areas.…”

Seroprevalence and Risk Factors of Leptospirosis Infection in Rural Community, Egypt

“…In our study we found that Particular animals present in the home or workplace were found to be significant risk factors and this was agree with Kamath et al (2014) who mentioned that rearing domestic animals at home , presence of rodents and seeing more than five rats per day at home or work place ,practices such as use of vegetables eaten by rats, contact with contaminated soil with rat's urine surrounding home could be a potential risk factor for the disease. Much more, Lau et al(2016) stated that variables associated with the presence of Leptospira antibodies included living in villages, working outdoors ,living in rural areas, living <100m from a major river ,and high cattle density in the district. It is known that infected enclosing domestic animals may be considered as source of contracting Leptospira.…”

Association between Opisthorchis viverrini and Leptospira spp. infection in endemic Northeast Thailand

“…The common risk factor is water contact since Leptospira and O. viverrini are both water-borne zoonotic diseases [5, 7, 29]. But this is not the sole explanation since the seroprevalence of leptospirosis was exceedingly high (71%) compared with other studies [35–37]. Is there cross reactivity between antigenic epitopes of O. viverrini and L. interrogans given that the maximum prevalence of O. viverrini in the Lawa Lake region is as high as 74% [17] and that over 70% of participants showed positive antibody to O. viverrini excretory-secretory antigens by ELISA (Sripa, unpublished)?…”