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| Author(s): |
Roseli La Corte dos Santos
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Saúde Pública (FSP/CIR) |
| Defense date: | 2001-03-28 |
| Examining board members: |
Oswaldo Paulo Forattini;
Marcelo Nascimento Burattini;
Iná Kakitani Murata;
Délsio Natal;
Ricardo Lourenço de Oliveira
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| Advisor: | Oswaldo Paulo Forattini |
| Abstract | |
Objective. Estimating the Vectorial Capacity of An. albitarsis and An. (Kerteszia) in order to establish the receptivity of the Ribeira Valley, São Paulo State, in relation to malaria, in natural environments as well as in environments modified by agricultural use. In order to this, we propose to determine the bites/man/day rate variation, the daily survival rate and the gonotrophic cycle duration for both groups. Material and Methods. The studies were carried out under laboratory and field conditions in two areas at the Ribeira Valley, one being a farm area with irrigated rice culture and the other one bordering on the Atlantic Forest. Data relating to the bites/man/day rate were obtained collaborating with the Thematic Project FAPESP 95/0381-4, using manual aspirator, during May/1996 until June/2000 for An. albitarsis and from May/1996 to September/1997 for An. (Kerteszia). The daily survival rate was estimated by linear regression of data obtained with the mark-release-recapture technique and physiological age study. The gonotrophic cycle duration in the field was studied by ovarioles dissection of released engorged females and in laboratory contidions by feeding females and observing them individually until oviposition. The parasite extrinsic cycle duration was determined using Oganov-Rayevsky method. Results. The bites/man/day rate ranged from zero to 628.5 for An. albitarsis and from 17.5 to 320.83 for An. (Kerteszia). The daily survival rate for An. albitarsis was 0.61 and for An. (Kerteszia) 0.45. The gonotrophic cycle duration for An. Albitarsis was 2.5 days in field and 4 days in laboratory conditions; for An. (Kerteszia) this was 3.5 days under laboratory conditions but could not be determined in field. The Vectorial Capacity was zero for both groups during cold months and in the hot ones showed peaks in January, February and March with a maximum value of 0.803 in February/1998 for An. albitarsis. For An. (Kerteszia) the maximum value was 0.081 in January/1997. Discussion. The Vectorial Capacity model demonstrated low possibility of endemic malaria occurence in the Ribeira Valley that could be attibuted to An. albitarsis. The obtained values for hot months showed the possibility of this species to participate secondary or sporadically as a vector. Such observations showed consistency with the history of malaria transmission attributed to this species. However, the given values by the model for An. (Kerteszia) contradict the actual malaria transmission in the region. The low values obtained for Vectorial Capacity of this subgenus were explained mainly by the daily survival rate. The difficulties in data analysis and its results suggest that there are features of this group which were not included in the presented model. (AU) | |