A cross-sectional study on canine Leishmania (L.) infantum chagasi infection in Amazonian Brazil ratifies a higher prevalence of specific IgG-antibody response than delayed-type hypersensitivity in symptomatic and asymptomatic dogs.
This was a cross-sectional study which analyzed the prevalence and the clinical and immunological spectrum of canine Leishmania (L.) infantum chagasi infection in a cohort of 320 mongrel dogs living in an endemic area of American visceral leishmaniasis in the Amazonian Brazil by using, mainly, the indirect fluorescence antibody test (IFAT-IgG) and the delayed-type hypersensitivity (DTH), and the parasite research by the popliteal lymph node aspiration. The IFAT and DTH reactivity recognized three different immune response profiles: (1) IFAT((+))/DTH((-)) (107 dogs), (2) IFAT((-))/DTH((+)) (18 dogs), and (3) IFAT((+))/DTH((+)) (13 dogs), providing an overall prevalence of infection of 43% (138/320). Thus, the specific prevalence of IFAT( (+) )/DTH( (-) ) 33.4% (107/320) was higher than those of IFAT( (-) )/DTH( (+) ) 5.6% (18/320) and IFAT( (+) )/DTH( (+) ) 4.0% (13/320). Moreover, the frequency of these profiles among 138 infected dogs showed that the IFAT( (+) )/DTH( (-) ) rate of 77.5% (107/138) was also higher than those of 13.0% (18/138) of IFAT( (-) )/DTH( (+) ) and 9.5% (13/138) of IFAT( (+) )/DTH( (+) ) rates. The frequency of asymptomatic dogs (76%-105) was higher than those of symptomatic (16.6%-23) and oligosymptomatic ones (7.4%-10). A total of 16 (11.6%) L. (L.) i. chagasi isolates were obtained from infected dogs, all from the IFAT( (+) ) /DTH( (-) ) profile: 41% (9/22) from symptomatic, 33.3% (3/9) from oligosymptomatic, and 5.2% (4/76) from asymptomatic dogs. These findings strongly suggested that despite the higher frequency of asymptomatic dogs (76%-105), the majority (72.4%-76) was characterized by the IFAT( (+) ) /DTH( (-) ) profile with a doubtful immunogenetic resistance against infection.
Parasitology Department, Evandro Chagas Institute (Surveillance Secretary of Health, Ministry of Health), Rod. BR 316-KM 07, Levilândia, Ananindeua 67.030-000, Pará State, Brazil. silveiraft@lim50.fm.usp.br
Fernando T
FT
Silveira
Liliane A
LA
Carneiro
Patrícia K S
PK
Ramos
Eugênia J
EJ
Chagas
Luciana V R
LV
Lima
Marliane B
MB
Campos
Márcia D
MD
Laurenti
Claudia M C
CM
Gomes
Carlos E P
CE
Corbett
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004283:Dog Diseases / Q000453:epidemiology* / Q000276:immunology* / Q000469:parasitology; D004285:Dogs; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006968:Hypersensitivity, Delayed / Q000453:epidemiology*; D007074:Immunoglobulin G / Q000097:blood*; D018314:Leishmania infantum / Q000276:immunology / Q000472:pathogenicity*; D007898:Leishmaniasis, Visceral / Q000150:complications / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D008297:Male; D015995:Prevalence
D000913:Antibodies, Protozoan; D007074:Immunoglobulin G