Asymptomatic human carriers of Leishmania chagasi.
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.
Costa
Carlos H N
CH
Department of Immunology and Infectious Disease, Harvard School of Public Health, Boston, Massachusetts, USA. costa@ranet.com.br
Stewart
Jay M
JM
Gomes
Régis B B
RB
Garcez
Lourdes M
LM
Ramos
Patrícia K S
PK
Bozza
Marcelo
M
Satoskar
Abhay
A
Dissanayake
Senarath
S
Santos
Regina S
RS
Silva
Mauro R B
MR
Shaw
Jeffrey J
JJ
David
John R
JR
Maguire
James H
JH
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
D018105:DNA, Kinetoplast