[Leish-l] Leishmaniasis - Argentina: epidemic potential

[Laila Nimri]

Just to correct a very important information about the vector of Visceral leishmaniasis, it is definitely not a mosquito, it is a sand fly of the genus Lutzomyia as mentioned correctly below or a Phlebotomus. The environmental or climatic changes that affect mosquitoes might have affected the sand flies and lead to the emergence of the disease.

Prof. Laila Nimri
________________________________
From: leish-l-bounces at lineu.icb.usp.br [leish-l-bounces at lineu.icb.usp.br] On Behalf Of fred opperdoes [fred.opperdoes at uclouvain.be]
Sent: Thursday, February 26, 2009 8:21 AM
To: Leish-l at lineu.icb.usp.br
Subject: [Leish-l] Leishmaniasis - Argentina: epidemic potential

Date: Wed, 25 Feb 2009 21:23:15 -0500 (EST)
From: ProMED-mail <promed at promed.isid.harvard.edu<mailto:promed at promed.isid.harvard.edu>>
Subject: PRO/AH/EDR> Leishmaniasis - Argentina: epidemic potential

LEISHMANIASIS - ARGENTINA: EPIDEMIC POTENTIAL
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Date: Tue 24 Feb 2009
Source: Datachaco.com [trans. Mod JGM, edited]
<http://datachaco.com/noticia.php?numero=17399>


The occurrence of cases of yellow fever made people pay attention to
mosquito-borne diseases, and dengue fever, which is currently
attacking with unusual strength in Paraguay, set another alarm in
Chaco, Corrientes, and Misiones provinces, which share borders with
Paraguay and Bolivia.

However, a new emerging disease has become the main epidemic threat
in Argentina: Visceral leishmaniasis. This little known disease is
being analyzed now as a cause for a sanitary red alert in Argentina.

Visceral leishmaniasis is also caused by a mosquito-borne parasite.
There is no vaccine for this disease, and therapy is instituted only
once a case is clearly defined. Its mortality rate is around 8 per
cent, and it has a particular feature: Dogs may act as reservoirs for
the parasite.

A summary of the life cycle of the parasite indicates that
_Lutzomyia_ insects infect dogs. These animals develop the disease
and transmit the parasite to another insect vector, which now is
capable of transmitting visceral leishmaniasis to humans. There is no
human-to-human transmission.

Since the very 1st case was reported in 2006, 36 persons have been
affected, and there are 4 deceased patients. The possibility of a
rapid increase in the number of cases is a reason for concern.

Last week 2 cases of visceral leishmaniasis were reported in Posadas.
One is an 18-year-old woman, and the other is a 21-year-old man, who
separately developed the symptoms of the disease. Some personnel from
the army are currently collaborating with municipal authorities in
Posadas for cleaning wastelands, which are considered breeding places
for insect vectors.

This health problem has become quite dangerous and important in the
main cities in Misiones province, and specialists warn that the
disease may reach other provinces in the short term.

"We are observing that the vector is spreading fast, and 2 corridors
have been established, one directing towards Resistencia and the
other one towards Corrientes. Also, the northern area of Entre Rios,
as well as Santa Fe, and Cordoba are vulnerable places. The mosquito
vector for visceral leishmaniasis has become an urban-living insect,
so there is a substantial risk for its presence in big urban
centers," explained Dr. Daniel Salomon, from the National Center for
Epidemics in Argentina's Ministry of Health.

"It is quite difficult to implement preventive measures, because
people are so in love with their pets," commented Dr. Salomon. There
are very few options for controlling the spread of the disease apart
from sacrificing sick animals.

In 2004, the 1st dog infected with the causative agent of visceral
leishmaniasis was detected. When 40 cases were reported in Misiones
province, the Ministry of Health issued a red alert. Nonetheless, the
current situation is much worse. In Posadas, it was determined that
7000 dogs actually have the parasite. Additionally, there are 300
infected dogs in Corrientes, and it is worth mentioning that in its
capital city, there are thousands of homeless dogs considered to be
infected with the parasite.

The analysis of the experience from Brazil and Paraguay indicates
that there is a probability of having one person infected for every
60 infected dogs. There is a high risk for an epidemic.

Sanitary authorities recommend that pets must not be carried to the
areas considered to be at risk. It is also advisable not to transport
dogs from the affected regions to other areas in the country. The
idea is to cut the transmission cycle of the parasite. Those persons
who may visit the northern part of Argentina must be immunized
against yellow fever as an ordinary preventive measure, and they must
leave their pets at home as an additional preventive measure.

"Visceral leishmaniasis was present in the northern part of South
America until migrating workers started moving it towards the south.
In early 2000, there were some important outbreaks in Campo Grande do
Sul and in Asuncion, where the average number of persons infected is
around 70 per year. In Brazil there are around 4000 cases and 200
deaths per year," pointed out Dr. Salomon, who had been doing some
field work during the past few weeks in the Litoral provinces.

He also added: "There is a trend for an increase in visceral
leishmaniasis, so the disease may spread, and it is expected to have
more cases."

Climate changes and deforesting seem to be the main explanations for
the migration of mosquito-borne diseases. However, trying to justify
the occurrence of emergent diseases only because of reasons inherent
to nature itself may exonerate provincial and municipal authorities
for not complying with their obligations with respect to the
implementation of disease control programs and cleaning empty lots.

Consequently, now there are many public accusations between Misiones,
Corrientes, and Chaco health officers. These persons, now that there
are cases of visceral leishmaniasis, immediately try to explain that
transmission may have taken place outside their respective
jurisdictions. The clear point is that the mosquito vector appears
because of lack of public hygiene.

- --
Communicated by:
ProMED-mail <promed at promedmail.org<mailto:promed at promedmail.org>>

[Leishmaniasis has been slowly spreading in northern Argentina over
the past decades (Salomon O et al. First visceral leishmaniasis focus
in Argentina. Mem Inst Oswaldo Cruz. 2008;103:109-11
<http://www.ncbi.nlm.nih.gov/pubmed/18368242?ordinalpos=9&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum>).

The ecology of the vector has been changing, and increasing
urbanization has been suggested as one of the explanations (Salomon
OD et al. Phlebotominae (Diptera: Psycodidae) fauna in the Chaco
region and Cutaneous Leishmaniasis transmission patterns in
Argentina. Mem Inst Oswaldo Cruz. 2008;103:578-84
<http://www.ncbi.nlm.nih.gov/pubmed/18949328?ordinalpos=3&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum>).
 - Mod.EP]
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