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Important article to establish effective control strategy against T. dimidiata

Posted by junnaka on 12 Jun 2008 at 03:43 GMT

This is an very interesting article. The absence of colonization in northern Guatemala, heavy infestation in South eastern Guatemala and western El Salvador has been know from the operational result, but this article provided scientific evidence to explain the geographic difference of the infestation pattern of T. dimidiata. Especially it is interesting that the highest risk areas are concide with the core distribution zone of T.d.dimidiata. The core distribution zone (where it is circled) has the highest infestation and reinfestation rate in Central America. The border area of Guatemala, El Salvador and Honduras, more specifically, Department of Jutiapa, Santa Rosa of Guatemala, Auachapan, Sonsonate of El Salvador and Copan of Honduras, are stratified as the highest risk areas, according to their vector control experience.

It is a bit disappointing that no samples from El Salvador are included where the infestation characteristics of the T.d. core distribution zone is quite unique. The western El Salvador such as Sonsonate department has extremely high infestation rate (>50% in some municipalities) as well as high T. cruzi infection rate (>40%). Also there are more than 100 cases of acute cases has been reported annually with Signo de Romaña, which is rarely observed in south eastern Guatemala, Honduras and Nicaragua. In the eastern part of El Salvador and in northern Nicaragua, infestation rate is lower as well as infection rate (<5%). It would be interesting to analize further the geographic difference of T.d.dimidiata. The frequent detection of acute cases with signo de romana may imply migration of sylvatic population of T. d. dimidiata which may transmit a new type of T. cruzi. The recent hurricane hit this area may affect some change in enveiroment.

Regarding strategy of control of T. dimidiata, this geographic variety imply the possibility of establishment of specific control strategy by sub-species, as these strategies were suggested in article such as Nakagawa et al (2003). T. d. dimidiata may be paid special attention, since it is cause the major transmission of Chagas disease with significant reduction of R. prolixus distribution due to the successful vector control campaign since 2000. Repeated spraying combining strong surveillance activities in the T.d.dimidiata core distritubion zone should be emphasized. Case detection and treatement, and introduction of impregnated mosquito net in area with T. sp.aff. dimidiata may be useful.