The Simuliidae of Brazil
Project overview
Simuliidae (blood-sucking blackflies) occur throughout Brazil in all vegetation zones. At least 70 species are known, but not all have been thoroughly described, causing considerable problems in identification. Simuliids are important in Brazil because of their nuisance biting and because several species transmit worms that cause mansonelliasis and onchocerciasis (river blindness). There are currently three lines of research; some of which are interrelated.
1. Biosystematics of the Simuliidae of Brazil
This long-term objective aims to provide a biosystematic monograph to the Simuliidae of the country. Apart from material collected specifically for this objective, some of the data from the other objectives will contribute to producing this overview.
2. Species complexes in Brazilian Simuliidae
The core work involved in this objective is cytological. As species complexes are described (eg amazonicum, oyapockense, incrustatum, guianense, exiguum) attempts will be made to relate known morphological variations to cytotaxa. Molecular techniques will be employed in this work as required. This objective was recently begun and relies on material (and funding) from the other objectives.
3. The effect of a hydroelectric dam on the onchocerciasis focus of Minacu
This is a multidisciplinary objective involving taxonomy, vector incrimination and parasitological research. Work was started in 2000 at Minacu, Goias, the site of a new focus of onchocerciasis in Brazil. Preliminary prevalence rates have been investigated with a new technique involving an initial triage using a serological test, followed by confirmation of seropositivity using DNA probes on skin biopsies and the Mazzotti test.
Identification keys to simuliid species in the area have been produced using a new image analysis system, which provides precise images of their diagnostic characters. Baseline data collected before the dam was constructed are now available to assess the effect of changed river flow on simuliid populations that occurred in 1997 on completion of the dam.
This pilot project is now being extended to the rest of Brazil in an effort to pinpoint new disease foci. Collaboration with the Oswaldo Cruz Institute and Brasilia University on simuliids as disease vectors in Brazil has been ongoing for two decades. Many papers on the epidemiology and transmission of mansonelliasis and onchocerciasis and the taxonomy of simuliids have resulted. Research is now entering a new phase where emphasis is being placed on the taxonomy and biogeography of Simuliidae although their importance to man and domestic stock is an underlying theme.
The effect of man-made environmental changes links the biotaxonomy and distributional studies to those of medical importance. The taxonomic element of this work is being correlated with similar studies in Ecuador, Colombia and Argentina. This expanding research network allows local scientists to carry out research of national importance, while facilitating the regional research approach maintained in the Natural History Museum.
31-Oct-2002 Dr B R Pitkin