Table 1. Cumulative rainfall, citywide incidence of leptospirosis requiring hospitalization, and incidence of Leptospira infection among a community-based cohort in Salvador, Brazil, 2013–2015*.
| Follow-up period (dates)* | Cumulative rainfall, cm (+ SD)† | Hospitalizations/100,000 population‡ |
Leptospira infection in period§ |
|||
|---|---|---|---|---|---|---|
| No. cases | Incidence (95% CI) | No. infected | Incidence (95% CI) | |||
| 1 (2013 Feb 2–Sep 10) | 126 (+ 13) | 88 | 3.29 (2.67–4.01) | 44 | 5.11 (3.74–6.80) | |
| 2 (2013 Sep 10–2014 Mar 14) | 81 (+ 21) | 46 | 1.72 (1.26–2.29) | 74 | 8.60 (6.81–10.67) | |
| 3 (2014 Mar 14–2014 Aug 8) | 93 (+ 16) | 40 | 1.50 (1.07–2.04) | 18 | 2.09 (1.24–3.28) | |
| 4 (2014 Aug 8–2015 Mar 3) | 57 (+ 11) | 23 | 0.86 (0.54–1.29) | 42 | 4.88 (3.54–6.54) | |
*We conducted 5 semiannual follow-up surveys for a community-based cohort of 861 residents of a community within Salvador, Brazil. A period was defined as the interval between 2 consecutive surveys. †The source of rainfall data is 4 weather stations maintained by the Brazilian Institute for the Environment and Water Resources (Instituto do Meio Ambiente e Recursos Hidrilcos), located 1.6 km from the study site. ‡Cases of hospitalized leptospirosis per 100,000 population in the city of Salvador, Brazil (pop. 2,675,656 in 2010), during the follow-up period. §We performed microscopic agglutination test to evaluate serologic evidence of Leptospira infections between 2 consecutive surveys. Cumulative incidence was calculated as the number of infections per 861 cohort subjects multiplied by 100.