title: Risk Factors Associated with Human Visceral Leishmaniasis in an Urban Area of Bahia, Brazil.
abstract: The early diagnosis of asymptomatic, acute, and subclinical Leishmania infections remains a challenge for controlling visceral leishmaniasis (VL). Individuals with acute VL represent <1% of Leishmania infections occurring in active transmission endemic areas. In this cross-sectional study with a prospective follow-up, we explored the risk factors associated with acquisition of Leishmania infection in an area with newly identified endemic VL.
  
  
  
  Ninety-four households were randomly selected from the study area, which included a population of 213 individuals (10% of the total population of Pé de Areia, Bahia, Brazil). Clinical and epidemiological surveys were prospectively performed to detect cases of asymptomatic infections, acute VL, and subclinical VL, using the leishmanin skin test (LST), and serological response to two Leishmania-specific antigens: rK39 and rK26.
  
  
  
  Within the 92 households included in the study, the prevalence of Leishmania infection in individuals detected by positive serology was 91/197 (46.2%; 95% CI: 0.3937-0.5316) and by LST was 29/114 (25.4%; 95% CI: 0.1834-0.3414). Reactivity to both antigens was detected in 64/197 individuals (32.5%; 95% CI: 0.2634-0.3931). Among 89 individuals diagnosed with leishmaniasis, we found acute VL in one (1%), subclinical VL in 20 (22.5%), and asymptomatic Leishmania infection in 68 (76.4%) subjects. Use of repellents and bed nets showed no significant protection (prevalence ratio [PR] = 1.01, p = 1.0). Interestingly, individuals residing in houses with a sand backyard had significant protection against Leishmania infection (PR = 1.24, p = 0.049) compared to those with a different type or no backyard. Moreover, the presence of cat or dog at home was also not a risk factor (dog: PR = 1.14, 95% CI: 0.80-1.64; and cat: PR = 1.19, 95% CI: 0.78-1.81). We conclude that in newly discovered areas of transmission of L. infantum infection with sylvatic reservoirs, periodic surveys may be helpful in identifying risk factors for infection and optimizing prevention guidelines.
authors.affiliation: 1 Department of Medicine, Federal University of Bahia , Salvador, Brazil .
authors.forename: Zuinara
authors.initials: Z
authors.lastname: Maia
authors.affiliation: 1 Department of Medicine, Federal University of Bahia , Salvador, Brazil .
authors.forename: Vivian
authors.initials: V
authors.lastname: Viana
authors.affiliation: 1 Department of Medicine, Federal University of Bahia , Salvador, Brazil .
authors.forename: Eduardo
authors.initials: E
authors.lastname: Muniz
authors.affiliation: 1 Department of Medicine, Federal University of Bahia , Salvador, Brazil .
authors.forename: Larissa Oliveira
authors.initials: LO
authors.lastname: Gonçalves
authors.affiliation: 2 Health Science Institute, Federal University of Bahia , Salvador, Brazil .
authors.forename: Carlos Maurício Cardeal
authors.initials: CM
authors.lastname: Mendes
authors.affiliation: 3 Division of Infectious Diseases, University of California , San Diego, California.
authors.forename: Sanjay R
authors.initials: SR
authors.lastname: Mehta
authors.affiliation: 1 Department of Medicine, Federal University of Bahia , Salvador, Brazil .
authors.forename: Roberto
authors.initials: R
authors.lastname: Badaro
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007898:Leishmaniasis, Visceral / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D014505:Urban Population; D055815:Young Adult
keywords: Reservoir host; Sand fly; Transmission; Visceral leishmaniasis