Carlos Ponce
Laboratorio Central de Referencia para Enfermedad de
Chagas y Leishmaniasis, Secretaría de Salud de Honduras,
Tegucigalpa, Honduras
Received 9 June 1999
Accepted 9 August 1999
Code Number:OC99213
Key words: Chagas disease - vector - control - Central America
Geographically, Central America is composed by seven
countries: Belize, Costa Rica, El Salvador, Guatemala, Honduras,
Nicaragua and Panama. The Central American isthmus is located
between the Pacific and Atlantic oceans, and unites South America
with North America, having a territorial extension of 550,000
km2 and a population of 35 million people. The second
country to report human cases of tripanosomiasis americana or
Chagas disease was El Salvador (Segovia 1913). In Honduras, the
first human case was reported during the decade of the 60
(León-Gómez et al. 1960). Earlier, the natural
infection by Trypanosoma cruzi had been reported in
Didelphis marsupialis (Robertson 1931). Chagas disease is a
priority problem for public health in Central America, specially in
El Salvador, Guatemala, Honduras and Nicaragua. The infection
prevalence estimated for the population of these four countries is
of 7% (approximately 2 million people). Chronic cardiopathy is the
most frequently observed manifestation. In Honduras 20% of chronic
cardiopathies are chagasic and 36% of pacemakers implanted are for
chagasic cardiopaths.
Out of the seven species of triatomines considered of mayor
importance for the transmission of T. cruzi to man, three of
them: Rhodnius prolixus, Triatoma dimidiata and R.
pallescens are the main vectors for Central America. R.
prolixus is the most efficient, and the one with mayor
vectorial action due to its short life cycle, and the high density
it reaches inside dwellings. It is found in El Salvador, Guatemala,
Honduras and Nicaragua associated strictly with human dwellings,
which is different than observed in Venezuela and Colombia were it
can be found in wild habitats.
In Honduras the infestation indexes in areas where this species
is prevalent, are less than the infestation indexes of areas where
only T. dimidiata exists, but the infection indexes
by T. cruzi in the population are higher for areas where
transmission occurs by R. prolixus than for those by T.
dimidiata (Ponce et al. 1993).
There is evidence that R. prolixus no longer exist
in Central America since the past century, but there is for the
other species of triatomines. First time it was found, was in El
Salvador in 1915. The hipotesis that it could have been introduced
to Central America has strengthened the genetic studies of the
populations of R. prolixus in Honduras and in Colombia,
which show that the samples of R. prolixus from
Honduras represent a subpopulation genetically limited and derived
from an original population from South America (Dujardin et al.
1998).
The autochthonous species T. dimidiata is considered the
second important vector in Central America. Descriptions made by
the Spanish conquerors in several parts of Central Ameica of
hematophic insects, coincide with this species, existing in the
seven countries, where there is the greater dispersion, and the
most wide diversity of domiciliary, peridomiciliary, and wild
environments. It also has an urban condition which makes it an
important vector in many cities of Central America, and some South
American countries were it also exists. The city of Tegucigalpa,
capital of Honduras, has topographical, climate, and dwelling
conditions, which are favorable for this vector, finding it
throughout the city (Ponce & Zeledón 1973). T.
dimidiata is the species responsible for the transmission in
Costa Rica, and is the only important species in Belize. R.
pallescens is considered the most important species in Panama,
and cannot be found in other Central American countries.
Isolated efforts directed towards the control of vectorial
transmission, took place until the decade of the 70 in various
Central American countries, without continuity to achieve success.
As a consequence of the national prevalence study, carried out in
Honduras during 1984, with the support of the World Health
Organization and the Pan-American Health Organization, a motivation
process for professionals, workers, and health authorities started.
It emphasized on the importance of organizing the actions for
vectorial transmission control, and for prevention actions. Part of
this process was the 1985 study on serological prevalence in blood
donors at endemic and nonendemic area hospitals, which revealed a
national index of 11.6% with hospital ranges from 0.5 to 20.2% .
This allowed to initiate in Honduras the control of the transfusion
transmission, through the serological screening for T. cruzi
of the blood donors, obtaining the approval of a law making
this control procedure mandatory.
The successful experience of the transfusion transmission
control done in Honduras has been and is still carried out in other
Central American countries with the support of the Pan-American
Health Organization. The transfusion transmission control in
Central America, has allowed for effective control of the second
infection way, strengthening the motivation process is an excellent
strategy to justify the political decisions for the control of
vectorial transmission.
In 1990, in the Health Secretariat, the National Program for
Control and Prevention of Chagas disease, was created. It is
dependent on the Vector Transmitted Disease Division, and works
coordinately with the Central Reference Laboratory for Chagas
Disease. In high endemic areas, control experiences take place,
along with operational investigations, clinical studies for disease
characterization, epidemiological surveillance, education
interventions, and promotion of dwelling improvement. At the same
time, and within Resolution XVI from the 1991 Sanitary Conference
celebrated in Washington, work is being done to strengthen the
political decisions which completed in 1997 with Resolution no. 13
of the XIII Meeting for the Health Sector of Central America
celebrated in Belize City, and the launched of the Initiative of
the Central American Countries for the Vectorial and Transfusion
Transmission Control of Chagas Disease, carried out in Tegucigalpa,
Honduras at same year. These achievements are now supported by
Resolution WHA 51.14. 51a. World Health Assembly celebrated in
Geneva in 1998.
The objectives of the Initiative of the Central American
Countries for the Vectorial and Transfusion Transmission Control of
Chagas Disease, are: (1) elimination of R. prolixus from El
Salvador, Guatemala, Honduras and Nicaragua, considering that it is
an introduced and strictly domiciliary species; (2) reduction of
the infestation and colonization indexes of T. dimidiata
throughout Central America, considering it being an autuctonous
species; (3) strengthening and total coverage of the screening of
blood donors for the absolute elimination of transfusion
transmission. Success obtained by the initiative of the Southern
Cone countries, and the launched of the initiative of the Andean
countries in 1997, motivates and warranties the success of the
initiative of the Central American countries.
Supported partially by the TDR Programme, WHO/World Bank/UNDP.
REFERENCES
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