Geographic Analysis as a Support Tool for Triatominae Control Programmes

GORLA DE

Annecy, France

Simposio; Chagas Disease Meeting; 2008

Fondation Merieux

<!-- @page { margin: 0.79in } P { margin-bottom: 0.08in; direction: ltr; color: #000000; widows: 2; orphans: 2 } P.western { font-family: "Times New Roman", serif; font-size: 12pt; so-language: es-ES } P.cjk { font-family: "Times New Roman", serif; font-size: 12pt } P.ctl { font-family: "Times New Roman", serif; font-size: 10pt; so-language: ar-SA } --> Geographic Analysis as a Support Tool for Triatominae Control Programmes David E Gorla. CRILAR-CONICET. La Rioja, Argentina. dgorla@crilar-conicet.com.ar The control of the vectorial transmission of Chagas disease is recognised as a major success in vector control at a large scale in the southern cone countries of South America. Uruguay interrupted the vectorial transmission by 1997, Chile in 1999 and Brasil in 2006. Argentina and Paraguay certified the interruption of the transmission in part of the territory. In spite of this realized success, the disease is still actively transmitted in the Gran Chaco region of Argentina. The epidemiological scenario for Chagas disease in the Gran Chaco is complex, and combines a number of environmental, socioeconomic and political factors that result in the persistence of the vectorial transmission of Chagas disease in the region. Towards the southern tip of the Gran Chaco, the region of Los Llanos in La Rioja province (Argentina) has been one of the hyper-endemic areas of Chagas disease. Since the mid 1980?s, when the decentralization of the national programme of Chagas disease started until 2003, vector control activities progressively stopped. By 2004, when the provincial government assigned provincial resources to reinstall the activities, there were rural communities where vector control activities have been absent for more than a decade. The presentation will analyse rural house infestation by T. infestans in areas were vector control activities were absent for more than 10 years, and the effects of vector control activities carried out by the Chagas Programme of La Rioja during the last four years. Activities by the control programme included the construction of a geographic information system that currently constitutes a platform for the design of field activities referred to insecticide application by programme staff and vigilance in the rural areas of the Los Llanos region. The working area covers a territory of about 100.000 kilometres and rural communities are highly dispersed, with human density of one person per sq kilometre. House infestation in the rural areas of Los Llanos was high, either in the intra (22.3%) or peridomestic (31%) structures. The construction of a GIS (with over 5000 georeferenced houses) allowed the detection of infestation hot-spots southwest of the area, with 61% and 66% of intra and peridomestic infestation, respectively. Cold-spots were also present, with 2.9% and 8.4% intra and peridomestic infestation, respectively at the east of the area. After a regular work by the provincial programme for Chagas disease since 2004, intradomestic infestation markedly dropped below 5% in most of the region, except in the Department Rosario Vera, where intradomestic infestation is still over 20% of the rural houses. Peridomestic infestation decreased but at a lower pace. Extremely high house infestations are now infrequently found in the area. The next challenge is to sustain the low infestation and reach complete elimination of intradomestic structures obtained during the last four years, and to reduce substantially the infestation of peridomestic structures to minimize the reinfestation chances of intradomiciles.