BACKGROUND Since the early 1990s, programs to control
Chagas disease in
South America have focused on eradicating domiciliary
Triatoma infestans, the main vector.
Seroprevalence studies of the chagasic
infection are included as part of the
vector control programs; they are essential to assess the impact of
vector control measures and to monitor the prevention of vector
transmission. OBJECTIVE To assess the interruption of domiciliary vector
transmission of
Chagas disease by T. infestans in
Paraguay by evaluating the current
state of
transmission in
rural areas.
METHODS A
survey of
seroprevalence of
Chagas disease was carried out in a representative sample group of Paraguayans
aged one to five years living in
rural areas of
Paraguay in 2008.
Blood samples collected on filter
paper from 12,776
children were tested using an
enzyme-linked immunosorbent assay.
Children whose
serology was positive or undetermined (n = 41) were recalled to donate a whole
blood sample for retesting. Their homes were inspected for current triatomine infestation.
Blood samples from their respective
mothers were also collected and tested to check possible
transmission of the
disease by a
congenital route. FINDINGS A
seroprevalence rate of 0.24% for
Trypanosoma cruzi infection was detected in
children under five years of age among the country’s
rural population. Our findings indicate that T. cruzi was transmitted to these
children vertically. The total number of infected
children,
aged one to five years living in these departments, was estimated at 1,691 cases with an annual
incidence of
congenital transmission of 338 cases per year. MAIN CONCLUSION We determined the impact of
vector control in the
transmission of T. cruzi, following uninterrupted
vector control measures employed since 1999 in contiguous T. infestans-endemic areas of
Paraguay, and this allowed us to estimate the degree of
risk of
congenital transmission in the country.