Epidemiology and control of American visceral leishmaniasis in the state of São Paulo, Brazil. Critical analysis and differential diagnosis of canine visceral leishmaniasis in the municipality of Espírito Santo do Pinhal, 2010 – 2014

Abstract

Visceral leishmaniasis (VL) is a serious public health issue present in 65 countries, affecting about half million
people in the whole world. It’s a disease that can lead to death. In Brazil, it has become endemic in 21 out of the
27 states with about 3 thousand new cases every year. One of the measures adopted by the brazilian program
for LV control is based on the diagnosis and euthanasia of LV positive dogs, once these animals are resevoirs of
the parasite that causes the disease. According to the World Health Organization (WHO), this measure should
be adapted to the reality of each place. In Brazil, serological tests are the basis for diagnosing dogs with the
disease, hence the importance of using sensitive, specific and low cost tests that are accessible and easy to
be used and handled, considering its importance for the public health and also for the measures adopted in
regards to the reservoir. Until 2011, the Ministry of Health would standardly use ELISA Bio-Manguinhos as a
presumptive test and RIFI Bio-Manguinhos as a confirmatory test. By the end of the same year, the protocol for
diagnosing dogs was replaced by TR-DPP®/ELISA Bio-Manguinhos, for presumptive testing and confirmatory
testing respectively. Another change that has been made was in regards to interpreting the combination of results
for diagnosis. The inconclusive diagnosis that was given to the reacting samples in the presumptive tests and
to the non-reacting samples in the confirmatory test have been excluded. Therefore, samples containing the
same caracteristics, positive for presumptive tests (TR-DPP®) and negative for confirmatory tests (ELISA)
are to be considered negative now. Aiming at verifying the perfomance of new tests and the possible impact
in the seroprevalence of infected dogs in the city of Espírito Santo do Pinhal (SP) due to the change in the
diagnosis protocol for Canine Visceral Leishmaniasis, this present study has analyzed the results obtained from
the inquiries from the years of 2012 and 2014 and compared them to those obtained in 2010, when the former
protocol was still in use.The samples from 2010 were reassessed by the techniques used in the new protocol, in
order to estimate the prevalence in the actual diagnosing conditions. Besides that, the indexes of positiveness,
specificity and agreement between both tests were determined. In this study, serum obtained in different inquiries,
serum of dogs from the city of Rio Claro (SP) negative for VL (control group) and serum of dogs infected by
other patogens different than Leishmania sp were added in order to verify possible cross-reactions, as well as
serum of animals with a positive parastiological and sorological status for Leishmania, aiming at analysing the
sensitiveness of the tests and eventual co-intections caused by patogens usually found in dogs through the use
of the immunochromatographic test SNAP®4Dx®. The results have shown a reduction in the seroprevalence of
infected dogs in the city of Espírito Santo do Pinhal between 2012 and 2014, and that this reduction wasn’t caused
by the introduction of the new diagnosing protocol for canine VL. In regards to the performance of the tests, TRDPP® was more specific than ELISA Bio-Manguinhos, that showed cross-reactiveness with Neospora caninum,
Babesia canis, Ehrlichia canis e Trypanosoma cruzi. There was a low level of agreement between the results