title: Repeated praziquantel treatments remodel the genetic and spatial landscape of schistosomiasis risk and transmission.
abstract: Repeated treatments with praziquantel reduce schistosomiasis prevalence and morbidity, but transmission persists and populations often recover within a few years. To identify factors associated with persistence, we surveyed and treated all identified Schistosoma mansoni infections in two rural Brazilian communities (Jenipapo and Volta do Rio) in 2009, 2012 and 2013. Eggs were collected from all infected individuals and genotyped with 11 microsatellite markers to evaluate parasite differentiation and diversity. After successive rounds of community-wide treatment, prevalence decreased from 45% to 24% then 16%. Intensity of infection decreased by 57% over this period, and the number of eggs transmitted to the environment decreased by 92%. During all time periods the majority of eggs were excreted by those >15years of age. The incidence was 23% in 2012 and 15% in 2013, consistent with a decrease in transmission. There was little immigration or gene flow over a distance of 6km. On reinfection, infrapopulations were moderately differentiated indicating that pretreatment multilocus genotypes were not fully reacquired. The effective population size responded to census population decline more rapidly than differentiation. Reinfection was concentrated in the downstream portion of Jenipapo, consistent with the observed increased human fecal contamination. At this scale and in this area S. mansoni infections exist on a fragmented landscape with a highly focal pattern of transmission that may facilitate future elimination.
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil; Bahiana School of Medicine and Public Health, Av. Silveira Martins, n° 3386, Salvador, Bahia 41150-100, Brazil.
authors.forename: Lúcio M
authors.initials: LM
authors.lastname: Barbosa
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil.
authors.forename: Eliana A
authors.initials: EA
authors.lastname: Reis
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil.
authors.forename: Cláudio R A
authors.initials: CR
authors.lastname: Dos Santos
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil.
authors.forename: Jackson M
authors.initials: JM
authors.lastname: Costa
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil.
authors.forename: Theomira M
authors.initials: TM
authors.lastname: Carmo
authors.affiliation: Center for Global Health and Diseases, Case Western Reserve University, Biomedical Research Building, 2109 Adelbert Rd., Cleveland, OH 44106, USA.
authors.forename: Peace T
authors.initials: PT
authors.lastname: Aminu
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil.
authors.forename: Thassila N
authors.initials: TN
authors.lastname: Pitanga
authors.affiliation: Mercer University School of Medicine, 1327 Stadium Drive, Macon, GA 31207-1302, USA.
authors.forename: Rafael
authors.initials: R
authors.lastname: Ponce-Terashima
authors.affiliation: Center for Global Health and Diseases, Case Western Reserve University, Biomedical Research Building, 2109 Adelbert Rd., Cleveland, OH 44106, USA.
authors.forename: Walter A
authors.initials: WA
authors.lastname: Blank
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil.
authors.forename: Luciano K
authors.initials: LK
authors.lastname: Silva
authors.affiliation: Gonçalo Moniz Research Centre, Oswaldo Cruz Foundation, Rua Waldemar Falcão, 121 Brotas, Salvador, Bahia 40296-710, Brazil; Bahiana School of Medicine and Public Health, Av. Silveira Martins, n° 3386, Salvador, Bahia 41150-100, Brazil.
authors.forename: Mitermayer G
authors.initials: MG
authors.lastname: Reis
authors.affiliation: Center for Global Health and Diseases, Case Western Reserve University, Biomedical Research Building, 2109 Adelbert Rd., Cleveland, OH 44106, USA. Electronic address: reb6@case.edu.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Blanton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005243:Feces / Q000469:parasitology; D005260:Female; D005787:Gene Frequency; D060005:Genotyping Techniques; D006801:Humans; D015994:Incidence; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D010270:Parasite Egg Count; D011223:Praziquantel / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population; D012550:Schistosoma mansoni / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D012555:Schistosomiasis mansoni / Q000188:drug therapy* / Q000453:epidemiology / Q000635:transmission; D055815:Young Adult
chemical_list: D000871:Anthelmintics; D011223:Praziquantel
keywords: Brazil; Effective population size; Extinction; Genetic differentiation; Praziquantel; Reinfection; Spatial analysis