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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060 EISSN: 1678-8060
Vol. 97, Num. 5, 2002, pp. 641-642
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Untitled Document
Mem Inst Oswaldo
Cruz, Rio de Janeiro, Vol. 97(5) July 2002, pp. 641-642
SHORT COMMUNICATION
Presence of American Cutaneous
Leishmaniasis Vectors Surrounding the City of Medellín, Colombia
Luz A Agudelo, Jaime Uribe, Diana
Sierra, Fredy Ruíz, Iván D Vélez+
Programa de Estudio y Control de
Enfermedades Tropicales, Universidad de Antioquia, Apartado Aéreo 1226,
Medellín, Colombia, +Corresponding author. Fax: +574-5716675.
E-mail: id_velez@yahoo.com
Received 28 August 2001
Accepted 28 February 2002
Code Number: oc02122
The presence of Lutzomyia
(Helcocyrtomyia) hartmanni, as a vector of Leishmania colombiensis
and L. columbiana (Verrucarum group), recently incriminated in the
transmission of leishmaniasis, and L. pia (Verrucarum group) are reported
for the first time in a periurban area of Medellín city. There is thus
a risk of leishmaniasis transmission in this town.
Key words: Lutzomyia spp.
vectors - urbanization - Medellín - Colombia
The annual number of cases of American
cutaneous leishmaniasis (ACL) diagnosed in Colombia has increased during recent
years to nearly 6,500 p.a. This is attributed to migration, deforestation, multiplication
of illicit drug plantations, civil war and disorder and changes in the behavior
of vectors. The latter may be linked due to climatic factors or human activities
that favour vector colonization of new environments. Transmission of Colombian
ACL typically occurs within forested areas, where people become infected whilst
hunting, tree-felling, etc. In 1984 there were reports from the Colombian Andean
region of vectors inside houses and epidemic outbreaks of ACL affecting whole
families, with the highest incidence in children (Vélez et al. 1987,
1991, Montoya-Lerma et al. 1999). During the 1990's urbanization of the disease
and its vectors led to cases of ACL in Colombia cities such as Bucaramanga (Sandoval
et al. 1998) and Sincelejo (Bejarano et al. 2001).
Medellín lies in the Aburra
Valley, where over 2 million people live, and is not considered as an endemic
area, since autochthonous cases of ACL and its vectors have not been reported.
But in May 1999 the observation of Lutzomyia biting man in a house in
Medellín, at an altitude of 1,650 m.a.s.l., motivated a search for anthropophilic
phlebotomines in the same area.
The study area is located on the
western slopes of the central range of the Colombian Andes (6°10'N, 75°35'W).
Landing catches on human bait were made in houses in urban and suburban areas
and in a gallery forest within a radius of ca. 500 m of the house where the
man had been bitten in May 1999. Catches were made from 18:00 to 1:00 h on five
nights between May 1999 and October 2001. The collected sand flies were taken
to the Entomology Laboratory, University of Antioquia (Programa de Estudio y
Control de Enfermedades Tropicales, PECET - Study and Control Programe for Tropical
Diseases) where they were cleared in lactophenol, mounted and identified.
Thirty two sand flies were captured
landing on human bait: 15 L. (Helcocyrtomyia) hartmanni (Fairchild &
Hertig), 10 L. columbiana (Ristorcelli & Van-Ty) and 7 L. pia
(Fairchild & Hertig). Two specimens of L. columbiana, five L.
hartmanni and one L. pia were caught inside houses and ten L.
hartmanni, eight L. columbian, and six L. pia were caught
in gallery forest.
L. hartmanni and L. columbiana
are species of some public health importance: L. hartmanni
was implicated as a vector of Leishmania (Viannia) colombiensis
in Santander and of Le. (V.) panamensis in Ecuador (Hashiguchi et al.
1985, Corredor et al. 1990). L. columbiana, a highly anthropophilic species
has been implicated as a vector of ACL (Montoya-Lerma et al. 1999) and Bartonellosis
in Colombia (Young & Duncan 1994, Ferro 2000). L. columbiana belongs
to the verrucarum group which includes other species involved in leishmaniasis
transmission, such as L. youngi (Feliciangeli 1991), L. evansi, L.
spinicrassa (Young & Duncan 1994, Ferro 2000) and L. ovallesi
(Feliciangeli et al. 1988, 1994).
This is the first report of Lutzomyia
in the surroundings of the city of Medellín. Sand flies were not
found in a previous study using sticky traps performed by a PECET team in 1987
and 1999. Sticky-traps transects were carried out from the city northwards,
at altitudes from 1,410 to 1,500 m.a.s.l. Each transect consisted of nearly
400 sticky traps that were placed in and outside of houses and suitable sites
nearby.
In the present study, flies were
collected at a higher altitude (1,650 m), in a deforested region used for cattle-grazing.
There are some remnants of secondary forest, but no recent human settlement.
Since the area had not been studied previously we cannot say that our finding
of sand flies is due to a recent introduction. In the present study area, 200
sticky traps were left for 10 days in and around houses. No phlebotomines sand
flies were caught. This result raises the question as to the suitability of
using sticky traps to determine the presence of sand flies in the city of Medellín.
Considering the recent finding of
autochthonous ACL cases and the presence of Lutzomyia species in
other Colombian cities, such as Bucaramanga and Sincelejo (Sandoval et al. 1998,
Bejarano et al. 2001), it would seem that certain sand flies are beginnig to
invade city environments, as observed elsewhere (Scorza et al. 1985, Aguilar
et al. 1998, Silva et al. 2001).
Phenomena such as global warming
could be a factor favouring the urbanization of phlebotomines. However, such
assertions lack data, such as long term studies on the phlebotomine fauna and
environments.
Although autochthonous cases of ACL
have not yet been reported from Medellín, the findings in the present
study suggest that there is a risk of active transmission in the city. Previous
epidemiological studies carried out during Le. (V.) panamensis and Le.
(V.) braziliensis outbreaks in the Colombian Andean regions, principally
deforested areas and coffee plantations, suggested that the man may be playing
a role as reservoir for these parasites (Vélez et al. 1987, 1991, Montoya
et al. 1990). Due to the intense migration of man from rural endemic areas to
the periphery of cities, such has occurred in Medellín, it is possible
that autochthonous cases could soon occur if man is indeed a source of infection.
City health authorities need to be aware of this risk and need begin clinical
surveillance measures to ensure the early detection of cases.
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Copyright 2002 Instituto
Oswaldo Cruz - Fiocruz
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