Evaluation of Change in Canine Diagnosis Protocol Adopted by the Visceral Leishmaniasis Control Program in Brazil and a New Proposal for Diagnosis

Abstract

The techniques used for diagnosis of canine visceral leishmaniasis (CVL) in Brazil ELISA and IFAT have been extensively questioned because of the accuracy of these tests. A recent change in the diagnosis protocol excluded IFAT and included the Dual-Path Platform (DPP). We evaluated the prevalence and incidence rates of Leishmania spp. before and after the change in the protocol. In addition, based on our results, we propose a new alternative that is less expensive for the screening and confirmation of CVL. Plasma samples were obtained from a serobank from dogs evaluated in a cross-sectional study (1,226 dogs) and in a cohort study of susceptible animals (n = 447), followed for 26 months. Serology testing was performed using ELISA, IFAT, and DPP. The incidence and prevalence of CVL were determined by using the protocol of the Visceral Leishmaniasis Control and Surveillance Program until 2012 (ELISA and IFAT using filter paper) and the protocol used after 2012 (DPP and ELISA using plasma). The prevalence was 6.2% and the incidence was 2.8 per 1,000 dog-months for the protocol used until 2012. For the new diagnosis protocol for CVL resulted in an incidence of 5.4 per 1,000 dog-months and a prevalence of 8.1%. Our results showed that the prevalence and incidence of infection were far greater than suggested by the previously used protocol and that the magnitude of infection in endemic areas has been underestimated. As tests are performed sequentially and euthanasia of dogs is carried out when the serological results are positive in both tests, the sequence does not affect the number of animals to be eliminated by the Control Program. Then we suggest to municipalities with a large demand of exams to use ELISA for screening and DPP for confirmation, since this allows easier performance and reduced cost.

Value of the oral swab for the molecular diagnosis of dogs in different stages of infection with Leishmania infantum

“…Regarding serology, we adopted two tests, in accordance with the Brazilian Ministry of Health, that advocated, by the end of 2011, the exclusion of the immunofluorescence assay and the inclusion of the rapid test DPP ® Canine Leishmaniasis (Biomanguinhos/FIOCRUZ/Rio de Janeiro, Brazil) for screening dogs, and the enzyme-immunoassay (EIE-Biomanguinhos/FIOCRUZ/Rio de Janeiro, Brazil) to confirm the positive results. This novel proto-col improved the diagnostic accuracy (Laurenti et al, 2014), and proved that the magnitude of infection in endemic areas was far greater than estimated with the old serological protocol (Coura-Vital et al, 2014). In the current study, serology provided 78.3% of the positive results, and detected Leishmania infection in 82.3% of the SD dogs and in 70% of the AD dogs, in contrast with another report that found low positivity in apparently healthy infected dogs (Grimaldi et al, 2012).…”

Dificuldades na execução das diretrizes do Programa de Vigilância e Controle da Leishmaniose Visceral em grandes municípios brasileiros

“…Ao serem questionados sobre quais seriam os motivos de haver recusa da população à eutanásia canina, os entrevistados citaram: afeto pelo animal (citado por todos); animais reagentes, porém oligosintomáticos ou assintomáticos (citado por todos); interferência de clínico veterinário particular (citado por todos); interferência 31 . Exames sorológicos podem gerar tanto resultados falsos positivos como falsos negativos (mantendo cães que podem infectar o vetor na comunidade) 31 .…”

“…Exames sorológicos podem gerar tanto resultados falsos positivos como falsos negativos (mantendo cães que podem infectar o vetor na comunidade) 31 .…”

Prevalência Da Leishmaniose Visceral Canina E Coinfecções Em Região Periurbana No Distrito Federal – Brasil

“…Até 2012, a leishmaniose visceral canina (LVC) era diagnosticada utilizando-se a Reação de Imunofluorescência Indireta (RIFI), um método recomendado para a confirmação de casos positivos detectados por ELISA (Enzyme-Linked Immunosorbent Assay) (2) . Recentemente, para melhorar a acurácia no diagnóstico da LVC, o PCVLV recomenda a utilização de um teste rápido imunocromatográfico, compreendendo os antígenos recombinantes rK26 e rK39, o DPP (Dual-Path Plataform; Bio-Manguinhos / Fiocruz, Rio de Janeiro, Brasil), para a triagem de cães infectados, e ELISA para confirmar os resultados positivos (8,9) .…”