Mem Inst Oswaldo Cruz, Rio de Janeiro, Vol. 105(6): 796-799, September 2010
Detection of Leishmania infantum in naturally infected
Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) and
Canis familiaris in Misiones, Argentina: the first report of a PCR-RFLP
and sequencing-based confirmation assay
Soraya Alejandra Acardi1/+, Domingo Javier Liotta1, María Soledad Santini2,Carlo Mariano Romagosa3, Oscar Daniel Salomón2
Laboratorio de Biología Molecular Aplicada, Facultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones,
Posadas, Misiones, Argentina 2Centro Nacional de Diagnóstico e Investigación en Endemo-epidemias,
Administración Nacional de Laboratorios e Institutos de Salud, Ministerio de Salud de la Nación, Buenos Aires, Argentina
3Instituto Municipal de Sanidad Animal, Secretaria de Calidad de Vida, Posadas, Misiones, Argentina
In this study, a genotypification of Leishmania was performed using polimerase chain reaction-restriction fragment length polymorfism (PCR-RFLP) and sequencing techniques to identify species of Leishmania parasites in
phlebotomine sand flies and dogs naturally infected. BetweenJanuary-February of 2009, CDC light traps were
used to collect insect samples from 13 capture sites in the municipality of Posadas, which is located in the province
of Misiones of Argentina. Sand flies identified as Lutzomyia longipalpis were grouped into 28 separate pools for
molecular biological analysis. Canine samples were taken from lymph node aspirates of two symptomatic stray animals that had beenpositively diagnosed with canine visceral leishmaniasis. One vector pool of 10 sand flies (1 out
of the 28 pools tested) and both of the canine samples tested positively for Leishmania infantum by PCR and RFLP
analysis. PCR products were confirmed by sequencing and showed a maximum identity with L. infantum. Given that
infection was detected in one out of the 28 pools and that at least oneinfected insect was infected, it was possible to
infer an infection rate at least of 0.47% for Lu. longipalpis among the analyzed samples. These results contribute to
incriminate Lu. longipalpis as the vector of L. infantum in the municipality of Posadas, where cases of the disease in
humans and dogs have been reported since 2005.
Key words: visceral leishmaniasis - Leishmania infantum - Lutzomyialongipalpis - A rgentina
Visceral leishmaniasis (VL) is the most severe clinical manifestation of leishmaniasis observed worldwide,
with an estimated incidence of roughly 500,000 cases
per year and a mortality rate of 59,000 deaths per year.
The primary parasite, vector and reservoir involved in
the transmission cycle in Latin America have been identified as Leishmania infantum, Lutzomyialongipalpis
and Canis familiaris (PAHO 2008), respectively.
The presence of Lu. longipalpis has been reported in
northeastern Argentina (specifically the cities of Candelaria and Corpus, in the province of Misiones) since
the 1950s (Salomon et al. 2001). However, it was not until the urban VL outbreaks of 2006 in the state of Mato
Grosso do Sul (MS), Brazil, and the city of Asunción,Paraguay, that the first human case of VL was reported
in Posadas, a city in the province of Misiones, Argentina. Investigations prompted by this case led to the discovery of Lu. longipalpis in the backyard of the home of
the infected individual; this was followed by diagnosis
of the disease in several dogs from the same neighborhood. The human case was confirmed by the presence of
parasites inbone marrow smears, as well as by culture,
serology (rK39 dipstick) and PCR (Leishmania genus);
f urthermore, parasite isolations were performed in the
canine confirmation procedure (Salomon et al. 2008).
By December of 2009, 39 human VL cases had been
reported in the urban area of Posadas, according to the
National System Surveillance of Health database.
Apart from immunoserological...