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On-line version ISSN 1518-8787Print version ISSN 0034-8910
Rev. Saúde Pública vol.37 n.5 São Paulo Oct. 2003
Roseli La Corte dos Santos
Centro Nacional de Epidemiologia/ Fundação Nacional de Saúde. Brasília, DF, Brasil
Updating regarding the distribution of Aedes albopictus in Brazil is presented for the period from 1997 to 2002. Data from the yellow fever and dengue information system of the National Health Foundation is utilized. It can be seen that this species is present in 20 of the 27 Brazilian states.
Keywords: Aedes. Ecology, vectors. Insect vectors. Dengue. Yellow fever. Geographic distribution. Aedes albopictus.
The first record of Aedes albopictus in Brazil was in 1986, in the State of Rio de Janeiro.2 In that same year, the species was then found in Minas Gerais and São Paulo and, in the following year, in Espírito Santo.1 Thus, within just one year, Ae. albopictus had become established in all the states of the southeastern region.
The National Health Foundation (FUNASA) receives data on infestation by Aedes aegypti and Ae. albopictus from all Brazilian states, by means of the yellow fever and dengue information system (FAD). This information comes from samples collected with a view to determining infestation rates in areas where Ae. aegypti is present. In addition to this, information is also generated from entomological surveillance, with the use of larvitraps or ovitraps, for municipalities that initially had no infestation.
According to recommendations from FUNASA, infestation surveys to determine Breteau and building indices, which generate information for the FAD, should be done every two months in infested municipalities and every four months in non-infested municipalities.3
The figure shows a map drawn up from corrected FAD information, indicating the municipalities where the presence of Ae. albopictus was recorded during the period from 1997 to 2002.
Rapid and increasing expansion of the occurrence of Ae. albopictus has been observed since its introduction into the country. Only seven Brazilian states have not yet reported infestation by this species: Amapá, Roraima, Acre, Tocantins, Piauí, Ceará and Sergipe, four of them in the northern region and three in the northeastern region. The States of Pará and Alagoas have recorded its occurrence in only one municipality each, Medicilândia and Maceió, respectively. It is important when analyzing the Figure to understand that the geographical unit utilized on the cartographic base is the municipality. The area covered by a single municipality may be very extensive in the northern region of the country. Thus, although the species may have been encountered in few localities within such municipalities, the entire municipality will be indicated on the map. It is also very probable that the indication of municipalities in the southeastern region without infestation but surrounded by others that are infested will reflect a lack of information rather than the absence of the species.
Although Ae. albopictus is subject to control pressure in areas infested by Ae. aegypti, it is not a target species in the dengue control programs. This may interfere in its notification rate among the Brazilian states. Because this is an exotic species, never before seen by a good proportion of the technicians responsible for mosquito identification, as well as their poor knowledge of entomology and the large work demands placed on them, it may be supposed the area of the northern and northeastern regions occupied by the species may have been underestimated. In addition to this, the recording of its occurrence in localities without dengue cases will depend on routine entomological surveillance, which is an activity that has not yet been implemented in all Brazilian municipalities.
This species has demonstrated a potential for occupying Brazilian rural and forest areas.4,6 Larvae may be found in holes in trees and imbrications of plant leaves. This penetration of the natural environment will give the possibility of including Ae. albopictus within the transmission cycles that until now have been maintained by Brazilian forest species. The demonstration that Ae. albopictus has vector competence for the transmission of the yellow fever virus5 and the expansion of the area it occupies within the national territory recorded in the present work point towards an increase in the area at risk of yellow fever, since the species can be active in both forest and human environments. It may thus both carry the virus from forest to human environments and favor virus maintenance in the urban environment.
The extent of the ecological penetration of Ae. albopictus means that its control will be difficult with the use of the same strategies as utilized for Ae. aegypti. Since this region has an environment rich in virus populations, many of them still unknown,7 the presence of Ae. albopictus may make it more receptive to the emergence of arboviruses, especially in areas of constant environmental change.
To Cátia Parreira and David H S Azevedo of the Health Surveillance Department of the Ministério da Sáude of Brasil, for processing the data from the yellow fever and dengue information system; to MB Arduino of the SUCEN ,São Paulo, Brazil ( Endemic Disease Control Office); to AS Fayal of the Secretaria de Saúde of Pará, Brazil; to AKR Gallardo of the Fundação Nacional de Saúde, Rio de Janeiro, Brazil; to FEM Sousa of the Secretaria da Saúde do Rio Grande do Sul, Brazil; to NA Santos of Secretaria da Saúde of Paraíba, Brazil; and to LB Costa of the Secretaria da Saúde of Mato Grosso, Brazil, for supplementary information.
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7. Vasconcelos PFC, Travassos-da-Rosa APAT, Rodrigues SG, Travassos-da-Rosa EST, Degallier N, Travassos-da-Rosa JFT. Inadequate management of natural ecosystem in the Brazilian Amazon region results in the emergence and reemergence of arboviroses. Cad Saúde Pública 2001;17 Supl:155-64. [ Links ]
Roseli La Corte dos Santos
Fundação Nacional de Saúde
Setor de Autarquias Sul
Quadra 4 Bloco N Sala 726
70070-040 Brasília, DF, Brazil
Reviewed on 28/4/2003.
Approved on 6/6/2003.