title: Asymptomatic human carriers of Leishmania chagasi.
abstract: In Brazil, programs based on elimination of infected dogs have not curtailed the spread of visceral leishmaniasis (VL), suggesting that other reservoirs of infection exist. Persons with active VL can infect the sand fly vector, but in endemic areas, persons with asymptomatic infections, whose infectivity to sand flies is unknown, are far more numerous. In this study, a polymerase chain reaction-based assay detected kinetoplast DNA of Leishmania chagasi in the blood of eight of 108 asymptomatic persons living with patients with recently diagnosed VL. These eight persons had low or unmeasurable levels of IgG antibodies to Leishmania, demonstrating the insensitivity of serology for subclinical infection. All eight persons had positive leishmanin skin test results, as did 70% of persons living in households of persons with active VL. Even if a small proportion of such asymptomatic persons are infective to sand flies, they represent a formidable reservoir of infection in endemic areas.
authors.affiliation: Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, Massachusetts, USA. costa@ranet.com.br
authors.forename: Carlos H N
authors.initials: CH
authors.lastname: Costa
authors.forename: Jay M
authors.initials: JM
authors.lastname: Stewart
authors.forename: Régis B B
authors.initials: RB
authors.lastname: Gomes
authors.forename: Lourdes M
authors.initials: LM
authors.lastname: Garcez
authors.forename: Patrícia K S
authors.initials: PK
authors.lastname: Ramos
authors.forename: Marcelo
authors.initials: M
authors.lastname: Bozza
authors.forename: Abhay
authors.initials: A
authors.lastname: Satoskar
authors.forename: Senarath
authors.initials: S
authors.lastname: Dissanayake
authors.forename: Regina S
authors.initials: RS
authors.lastname: Santos
authors.forename: Mauro R B
authors.initials: MR
authors.lastname: Silva
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Shaw
authors.forename: John R
authors.initials: JR
authors.lastname: David
authors.forename: James H
authors.initials: JH
authors.lastname: Maguire
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D001938:Brazil / Q000453:epidemiology; D002353:Carrier State / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology*; D018105:DNA, Kinetoplast / Q000097:blood; D006801:Humans; D018314:Leishmania infantum / Q000235:genetics / Q000302:isolation & purification*; D007898:Leishmaniasis, Visceral / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D018105:DNA, Kinetoplast