Examining the relationship between infectious diseases and flooding in Europe: A systematic literature review and summary of possible public health interventions

Brown, Lisa; Murray, Virginia

In Marseilles, France the incidence of leptospirosis identified in the laboratory increased significantly between January 2001 and July 2011 (p < 0.0001). 38 Between 1991 and 2003, the rate of leptospirosis incidence in southern France was very low, 0.09 cases/100,000 inhabitants. In 2008, this incidence increased to England. The risk of gastroenteritis was significantly associated with depth of flooding in people whose households were flooded (RR = 1.7; 95% CI 0.9-3.0; p for trend by flood depth = 0.04). Additionally, an outbreak of norovirus in American tourists was linked to direct exposure to floodwater contaminated with raw sewage in Germany. 29 Earlier research has shown an association between waterborne diseases and flooding in high-income countries. From 1948-1994, more than half of the water-borne disease outbreaks in the United States were preceded by heavy rainfall (p = 0.002). 30 Research from Finland found that 13 water-borne disease outbreaks from 1998-1999 were associated with un-disinfected groundwater contaminated by floodwaters and surface runoff. 32 Surveys in high-income countries where individuals reported their own symptoms have indicated an increase in water-borne diseases following flooding. 28, [30] [31] [32] Rodent-borne Rodent-borne diseases are climate sensitive and may increase during heavy rainfall and flooding because of altered patterns of human-pathogen-rodent contact. 15 Flooding and heavy rainfall have been associated with numerous outbreaks of leptospirosis from a wide-range of countries around the world. 15, 21, [33] [34] [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] Areas at the highest risk for leptospirosis outbreaks are those where multiple risk factors are likely to coexist; such as, increased flooding Ahern et al. 15 reviewed earlier studies addressing flood-associated outbreaks of leptospirosis from a wide-range of countries: Argentina, Brazil, Cuba, India, Korea, Mexico, Nicaragua, Portugal, and Puerto Rico. In 1997 in the Krasnodar Territory in Russia, a severe outbreak of leptospirosis took place in connection with a high flood. 49 Sanders et al. 50 stated that flooding after heavy rain favors leptospires. It prevents animal urine from being absorbed into the soil or evaporating; therefore leptospires may pass directly into the surface water or persist in mud. The evidence of this review, supported by several other reviews, suggests the association between leptospirosis and flooding is fairly robust even in high-income countries.