| Summary: | The ‘Southern Cone Initiative’ was highly successful in significantly reducing populations of <i>Triatoma infestans</i>, the main vector of Chagas disease in Latin America. New methodologies are required to detect re-emerging <i>T. infestans</i> populations at an early stage after control programmes have finished. This study analysed the IgG antibody response of chickens and guinea pigs to the saliva of <i>T. infestans</i>. Highly immunogenic antigens (14, 21, 26 dDa) were recognised as soon as two days after the first exposure to bug bites by all chicken sera and a 79 kDa protein by all guinea pig sera. An IgM response to saliva of <i>T. infestans</i> was already detectable after one after the first exposure and last up to 18 days. Out of four identified proteins by mass spectrometry, a 14.6 kDa antigen (r<i>Ti</i>SP14.6) was expressed and tested against animal sera from laboratory studies and from free-living hosts of <i>T. infestans</i> from Bolivia. Cross reactivity experiments with salivary proteins of other haematophagus species confirmed the usefulness of r<i>Ti</i>SP14.6 not only as an epidemiological marker for the detection of low-level infestation of <i>T. infestans</i> but also for at least four other triatomine species. Field samples suggest that r<i>Ti</i>SP14.6 is also a potential exposure marker for dogs. Data on national vector control programmes in Bolivia demonstrated that present control measures for <i>T. infestans </i>are inefficient. Using r<i>Ti</i>SP14.6 households omitted form control campaigns or identified as free from traitomine infestation were tested positive for bug exposure. Thus, r<i>Ti</i>SP14.6 represents a useful immuno-epidemiological marker for the detection of low-level infestations of different triatomine species, especially for countries with Chagas disease control programmes.
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