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Biomedical subjects

R Chuit

Publications and source records attributed to R Chuit.

At least 19 recordsLinked to original sources
PubMed2000

Peridomestic distribution of Triatoma garciabesi and Triatoma guasayana in north-west Argentina.

The Reduviid bugs Triatoma garciabesi Carcavallo et al. (Hemiptera: Reduviidae: Triatominae), previously known as T. sordida Ståhl in the semi-arid chaco region, and T. guasayana Wygodzinsky & Abalos, vectors of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), were found to occupy wide but different ranges of ecotopes in the peridomestic environment. At Amamá and nearby rural villages in north-western Argentina, a combined total of 1233 specimens were collected from 325/2314 (14%) sites surveyed at 6-monthly intervals from November 1994 to November 1996. Triatoma garciabesi and T. guasayana displayed a significantly different distribution among peridomestic ecotopes. Triatoma garciabesi predominated over T. guasayana in the prevalence of infested sites, the number of colonies and the number of bugs collected. For T. garciabesi, the predominant ecotopes most likely to yield T. garciabesi repeatedly were the rugged bark of Prosopis alba or P. nigra (Fabaceae) trees, where chickens roosted, and chicken coops. For T. guasayana the main ecotopes were goat or sheep corrals, piled materials and orchard fences. Triatoma garciabesi and T. guasayana were collected concurrently from the same site on 9/2314 (0.4%) occasions, and on different dates at the same site on 12 (0.5%) occasions. The observed low frequency of mixed populations (< 1%) was not significantly different from that expected from a hypothesis of independence. Triatoma garciabesi clearly outnumbered T. guasayana in four of the nine mixed populations, none of which persisted as such. Neither T. garciabesi nor T. guasayana colonized human habitations, even in the absence of T. infestans (formerly the predominant domestic vector of T. cruzi in this area), a situation that apparently has not changed in the last 50 years in northern Argentina.

Animals↗
PubMed2000

Congenital transmission of Trypanosoma cruzi: an operational outline for detecting and treating infected infants in north-western Argentina.

We designed a set of procedures for first-line local health services to detect and treat the congenital transmission of Trypanosoma cruzi at a province-wide scale, and field-tested the programme in the province of Tucumán, northwestern Argentina, from 1992 to 1994. The programme consists of routine screening of pregnant women for seroreactivity to T. cruzi, serological and parasitological follow-up of the newborn at least twice during the first year of age, treatment of the infected infants, and evaluation of the outcome. 927 (5.5%) of 16 842 pregnant women were seroreactive to T. cruzi by indirect haemagglutination assay and ELISA. Twenty-one (6.7%) of 315 newborns to seroreactive mothers were diagnosed as infected with T. cruzi parasites microhaematocrit concentration before 30 days of age. Five newborns who initially tested negative had a T. cruzi infection detected by microhaematocrit and/or serological techniques at 3 or 6 months of age. Thus, congenital infection was diagnosed in 26 (7.1%) infants born to seroreactive women and residing in houses free of triatomine bugs. Four of 6 infants born to seroreactive mothers died during the first year of age and had some evidence of T. cruzi infection; one of the deaths was attributed to T. cruzi based on clinical evidence. After specific treatment with nifurtimox or benznidazole, 30 of 32 infants remained parasitologically and serologically negative. This study shows the feasibility of controlling the incidence of congenitally acquired T. cruzi infections at a province-wide scale by means of a specific screening programme at first-line health services level.

Adult↗
PubMed1999

Monitoring house reinfestation by vectors of Chagas disease: a comparative trial of detection methods during a four-year follow-up.

Domestic reinfestations by triatomine bugs were monitored after application of deltamethrin and apparent elimination of Triatoma infestans in Amama and other nearby rural villages, north-west Argentina, from 1992 to 1996. The five methods used were sensor boxes, sheets of pink typing-paper, timed manual catches by a skilled three-person team aided by a flushing-out agent, collections by house-dwellers, and knockdown using insecticide fumigant canisters. In bedrooms, house-dwellers collected T. infestans significantly more frequently than the flushing-out method, but the reverse occurred in peridomestic sites. Both methods and sensor boxes revealed the frequent invasion of adult Triatoma guasayana and T. infestans, but neither T. guasayana nor Triatoma sordida colonized bedroom areas in spite of their rising abundance in nearby peridomestic sites. Sensor boxes were significantly more sensitive than the matched paper-sheets in three of five cross-sectional surveys. On average, each box recorded 2.0-3.2 times more triatomine fecal smears than each paper sheet. The frequency of dejecta in sensor boxes correlated positively with the proportion of houses where T. infestans, T. guasayana or T. sordida were captured by any method in bedroom areas. Triatomine fecal smears in sensor boxes were the earliest and most frequent sign of domiciliary infestation, followed by dwellers' collections of adult bugs. Analyzing the data prospectively, we provide a quantitative, predictive understanding of detection methods and review the validity and interpretation of the different signs of infestation obtained. The most sensitive and cost-effective combination of detection methods for vector surveillance in domestic areas was the use of sensor boxes and house-dwellers collections.

Animals↗
PubMed1999

Small-scale field trial of a sensing device for detecting peridomestic populations of Triatoma infestans (Hemiptera: Reduviidae) in northwestern Argentina.

Two prototypes of sensing devices for detecting peridomestic populations of Triatoma infestans Klug were tested in paired trials with bamboo canes in Amamá and nearby rural villages under triatomine surveillance. In infested peridomestic structures housing domestic animals, 1-2 pairs of numbered devices were placed per test site, left for 3-9 nights, and inspected for evidence of infestation. Prototype A was a black plastic cylinder 19 cm high and 10 cm diameter, with a screw cap on the top, 2 openings in the bottom, and a removable central structure made of resistant plastic coated with leather. Prototype B had square leather pieces rolled into cylinders instead of the central structure. Prototype A was significantly more sensitive than the bamboo cane with pleated paper inside in 13 test sites in which 20 pairs were tried. In a smaller series involving 7 pairs, prototype B also detected infestations more frequently than the cane. Triatomine feces were the signs most frequently recorded by both prototypes, whereas the bamboo canes recorded no feces. Ten T. infestans and 1 Triatoma guasayana Wygodzinsky & Avalos were collected from the prototypes placed on the ground or walls, not beneath the thatched roofs of the animal shelters, whereas only 3 T. infestans were collected from the canes. This study describes an effective sensing device for detecting T. infestans populations in outdoor animal shelters and provides quantitative field data on its performance.

Animals↗
PubMed1999

Risk of death due to chronic chagasic cardiopathy.

In this longitudinal study 5,710 people were included. The inclusion criteria were two positive serological results for Trypanosoma cruzi infection, 15 and 50 years old and no other demonstrable disease at the time of study. In the five year follow up 1,117 patients were lost. The follow up involved yearly evaluation of serology, clinical examination, X-ray of thorax, and ECG, for 4,593 patients and 263 were contacted at home because they did not assist for their clinical consultant. Time average of follow up was 5.3 years. Eighty nine (1.5%) of the 4,593 patients died during the follow-up period, 63 (71%) by cardiac insufficiency (CI) and 26 (29%) by severe ventricular arrhythmias. Diagnosis of cardiomegaly was present in all the patients with diagnosis of CI and in 15 (5%) of the patients with diagnosis of arrhythmias. The ECG alterations of these patients show 61 right bundle branch block (RBBB), associated or not with left anterior hemiblock (LAHB), 47 pathological Q wave and 70 primary repolarization alterations; 61 had polyfocal ventricular arrhythmia. The death rate was similar in the sexes and was more frequent between 40 and 50 years of age. Information on 1,380 recuperated patients shows that 15 died with no previous symptoms and without medical assistance and were interpreted as sudden death. The latest ECG in three follow-up of these patients indicates (before death) that only one had normal study and 14 presented 12 RBBB; 9 LAHB; 7 isolated ventricular arrhythmia; 10 repolarize alterations; 2 pathological Q wave, 10 patients of them with RBBB and repolarize alterations. In all the cases we had people between 35 and 43 years old, 9 men and 6 women. This study shows that in Chagas disease is possible to differentiate two risk groups. A low risk death group that have normal ECG and clinical evaluation during the follow up, and a high risk group associate ECG with RBBB and primary alterations of repolarization and/or inactivation zones with not annual clinical evaluation.

Adolescent↗
PubMed1999

Trypanosoma cruzi infection in Triatoma infestans and other triatomines: long-term effects of a control program in rural northwestern Argentina.

The prevalence of Trypanosoma cruzi infection in Triatoma infestans, Triatoma guasayana, and Triatoma sordida was evaluated in Amamá and other neighboring rural villages in northwestern Argentina for five years after massive spraying with deltamethrin in 1992 and selective sprays thereafter. Local residents and expert staff collected triatomines in domiciliary and peridomestic sites. During 1993-1997, the prevalence of T. cruzi was 2.4% in 664 T. infestans, 0.7% in 268 T. guasayana, and 0.2% in 832 T. sordida. T. cruzi infection was more frequently detected in adult bugs and in triatomines collected at domiciliary sites. The infected T. guasayana and T. sordida were nymphs and adults, respectively, captured at peridomestic sites. The prevalence of T. cruzi infection in T. infestans decreased from 7.7% to 1.5% during the surveillance period, although that change was not statistically significant. Comparison of T. infestans infection rates before the control program and during surveillance showed a highly significant decrease from 49% to 4.6% in bedrooms, as well as a fall from 6% to 1.8% in peridomestic sites. Because of its infection with T. cruzi and frequent invasion of domiciliary areas and attacks on humans and dogs, T. guasayana appeared implicated as a putative secondary vector of T. cruzi in domestic and peridomestic sites during the surveillance period. T. sordida was the most abundant species, but it was strongly associated with chickens and showed little tendency to invade bedrooms.

Animals↗
PubMed1998

Evaluation of dogs as sentinels of the transmission of Trypanosoma cruzi in a rural area of north-western Argentina.

Dogs, the main domestic reservoirs of Trypanosoma cruzi in the Argentine chaco, may be useful as sentinels of vector-mediated transmission of Trypanosoma cruzi in control programmes if canine infections acquired by all other routes could be excluded. In the present study, in the province of Santiago del Estero, Argentina, the dog populations in the neighbouring villages of Amamá, Trinidad, Mercedes, Villa Matilde and Pampa Pozo were studied immediately before spraying of residual insecticides (in 1992 in Amamá, Trinidad and Mercedes and 1993-1994 in the other villages) and twice during a subsequent programme of triatomine surveillance (in 1994 and 1996). Overall seropositivity for Trypanosoma cruzi infection (i.e. the proportion of dogs found positive by at least two different serological tests in any one survey) steadily declined from 65% (54/83) in 1992 to 39% (70/182) in 1994 and 15% (36/237) in 1996. No seroconversion was detected between the 1994 and 1996 surveys in any dog aged > 2 years. However, among the dogs aged < 2 years (which were born after virtual elimination of Triatoma infestans from the villages), seropositivity fell from 15% (12/81) in 1994 to 5% (6/131) in 1996. Thirteen demographic, behavioural and entomological variables were analysed by logistic multiple-regression analysis for their association with seropositivity in dogs born locally during the surveillance programme. The total number of Triatoma guasayana collected in the bedroom areas of the owner's house, having a mother which was seropositive for Trypanosoma cruzi, and the number of seropositive dogs with which it cohabited were all found to be significant predictors of seropositivity in any dog. The results are the first indication that Triatoma guasayana is the vector responsible for the new cases of Trypanosoma cruzi infection seen in dogs in domestic or peridomestic sites during the surveillance programme.

Animals↗
PubMed1998

Influence of humans and domestic animals on the household prevalence of Trypanosoma cruzi in Triatoma infestans populations in northwest Argentina.

In three rural villages of northwest Argentina, the overall proportion of domiciliary Triatoma infestans infected with Trypanosoma cruzi was 49% among 1,316 bugs individually examined for infection in March and October 1992). Most of the variation among individual households in the proportion of infected triatomines was explained by variations among houses in the proportion of bugs that fed on dogs or cats, the prevalence of infected dogs or cats, and the proportion of bugs that fed on humans, according to a logistic multiple regression analysis. The effects of human infection rates on bug infection rates were not statistically significant. After adjusting for the effects of other predictors, the presence of chickens in bedroom areas had negative and significant effects on the proportion of infected Triatoma infestans, and positive and significant effects on the number of T. cruzi-infected triatomines collected per person-hr per house. Dog or cat infection rates and the proportion of bugs that fed on dogs or cats and on chickens explained 80% of the total variance of infected-bug numbers in a linear multiple regression model. This is the first study to use detailed field data to show that variations in triatomine infection rates depend on bug host feeding patterns and dog or cat infection rates, while the presence of chickens in bedroom areas exerts opposite effects on the proportion and number of infected triatomines. Domestic animals play a crucial role in the domiciliary transmission of T. cruzi.

Animals↗
PubMed1998

Household prevalence of seropositivity for Trypanosoma cruzi in three rural villages in northwest Argentina: environmental, demographic, and entomologic associations.

Environmental, demographic, and entomologic variables were analyzed by logistic multiple regression analysis for their association with the likelihood of being seropositive for Trypanosoma cruzi in three highly infested rural villages of northwest Argentina. The prevalence of seropositivity for T. cruzi, as determined by the composite results of three serologic tests, was 34% among 338 persons in 1992. The strongest positive predictors of the adjusted odds of being infected were the household number of dogs, the density of T. cruzi-infected Triatoma infestans in bedroom areas, and each person's age. Dwellers from houses with roofs made completely or partly with a grass called simbol, or which used insecticides rudimentarily and nonsystematically, had a significantly lower odds of being seropositive for T. cruzi than residents from other types of dwellings. The adjusted odds of infection also increased with the number of T. cruzi-infected dogs or cats and the presence of chickens in bedroom areas. No significant effects on the adjusted odds of infection of a community-wide deltamethrin spraying carried out in one of the villages seven years before were detected. Socioeconomic indicators, such as domiciliary area, and numbers of corrals and livestock, were inversely related to being infected. Our study identified several manageable variables suitable for control actions, most of them not examined before in univariate or multivariate analyses. Environmental management based on low-cost housing with appropriate local materials and removal of domestic animals from domiciliary areas have a crucial role to play in the control of Chagas' disease in rural areas.

Adolescent↗
PubMed1998

Factors that make difficult the implementation of an integrated leprosy control programme in health zone II, Santa Fe Province, Argentina.

With the help of a pre-tested, structured questionnaire and participatory observation, effects of several variables that have a bearing on the process of integration were studied in Zone II of the Santa Fe Province of Argentina. Patient's knowledge and the presence of an NGO were identified as factors facilitating integration. The presence of a vertical programme staff and insufficient commitment towards integration were identified as factors hindering integration.

Delivery of Health Care↗
PubMed1998

Factors limiting the domestic density of Triatoma infestans in north-west Argentina: a longitudinal study.

Reported are the environmental and demographic risk factors associated with the domestic infestation and density of Triatoma infestans in three heavily infested rural villages in Santiago del Estero Province, Argentina. In a one-factor unadjusted analysis, the number of T. infestans captured per person-hour was associated significantly and negatively with the use of domestic insecticides by householders, type of thatch used in the roofs and the age of the house; and positively with the following: degree of cracking of the indoor walls and presence of hens nesting indoors. In one model, using multiple linear regression and a backward stepwise elimination procedure, most of the variation in the overall abundance of T. infestans was explained by insecticide use and the presence of hens nesting indoors; in another model using the same procedure it was explained by insecticide use, bug density in 1988 and previous spraying with deltamethrin in 1985. Variations in bug density per capture stratum (household goods, beds, walls and roof) were explained by the bug density in other strata and by one or two of the following risk factors: hens nesting indoors, type of roof, presence of cracks in the walls and number of people living in the house. Bug density might be locally controlled by the availability of refuges in the roofs and walls, by the presence of hens nesting indoors and by the use of domestic insecticides. Certain local materials, such as a grass known as simbol, could be successfully used in rural housing improvement programmes aimed at reducing the availability of refuges for insects in the roof.

Adult↗
PubMed1997

Effects of chickens on the prevalence of infestation and population density of Triatoma infestans in rural houses of north-west Argentina.

Effects of the presence of chickens on population density of the bug Triatoma infestans, principal vector of Chagas disease, were investigated by standardized sampling (indoors and peridomestically) from sixty-eight houses of three rural communities in north-west Argentina, during March 1992. The domiciliary density of T. infestans increased linearly with the percentage of bugs that fed on chickens, as identified by agar double-diffusion tests. Bug density was significantly higher in houses where hens usually nested indoors than in those where they did not, as determined by concurrent direct observations and interviews of householders. Multiple linear regression analysis of domiciliary bug density on (a) the total number of people, dogs and cats per house; (b) the percentage of domiciliary bugs that fed on chickens, or (c) the indoor-brooding habit of hens, showed the two variables (b,c) related to chickens as significant predictors in each regression model. Inclusion both variables representing chickens increased the fit significantly. Addition of other potentially confounding factors (domestic insecticide use, type of roof and walls of house) did not affect the significant variables retained in the best-fitting regression model. Peridomestic infestation was positively associated with the household number of fowls. Chickens were the main bloodmeal source of peridomestic T. infestans populations. Human-fed bugs were detected in peridomestic sites of sixteen houses, indicating active dispersal of adults and large nymphal instars from bedroom areas. Exclusion of hens from domiciliary areas and promotion of chicken sheds, of an appropriate design that would not harbour bug populations, should limit the triatomine population growth rate and reduce the risk of infestation.

Animals↗
PubMed1997

The role of the peridomiciliary area in the elimination of Triatoma infestans from rural Argentine communities.

The purpose of this study was to identify the origin of Triatoma infestans reinfestation and study its dynamics following spraying with deltamethrin inside and around 94 houses in three rural communities in northwestern Argentina. The effectiveness of the spraying was evaluated immediately after the houses were sprayed and two months later. In addition, five residual peridomiciliary foci were found and sprayed, as well as three preexisting ones that had not been sprayed. To monitor reinfestation, biosensors were placed in the houses and each family was also asked to capture triatomines and keep them in plastic bags; in addition, triatomines were searched for in and around houses, using an aerosol that dislodged them from their hiding places. Selective sprayings were carried out only where a colony of T. infestans was found. During the 30 months of follow-up, the percentage of houses in which any T. infestans were captured varied between 3% and 9%. In six houses, T. infestans were captured during more than one evaluation. The number of peridomiciliary areas found to be infested (19) was double the number of infested houses (9). Colonies of T. infestans were found only in the peridomiciliary areas, where the number of T. infestans captured was six times higher than in the houses. Chickens were the host most frequently associated with peridomiciliary foci. This area was the origin and principal source of reinfestation. To reduce the speed of reinfestation and the frequency with which sprayings are needed, the following environmental and chemical control methods must be combined in the peridomiciliary area: reduce the number of hiding places of triatomines; restrict the raising of birds to structures that cannot be colonized by triatomines; apply an insecticide that is less likely to be degraded by exposure to the elements, or perform a second spraying 6 to 12 months after the first; and employ a device for early detection of the presence of T. infestans around houses.

Aerosols↗
PubMed1996

Host-feeding patterns of domiciliary Triatoma infestans (Hemiptera: Reduviidae) in Northwest Argentina: seasonal and instar variation.

Blood meal sources of 1,964 Triatoma infestans Klug collected in bedrooms in 3 rural villages in northwest Argentina were identified by agar double-diffusion tests. Bugs were collected in September (1988, end of winter), October (1992), December (1988, spring), and March (1989, 1992, summer), and tested for human, dog, cat, chicken-duck, and goat-sheep serum antigens. From late winter to late summer, the percentage of domiciliary T. infestans that fed on humans decreased from 81 to 50-51%, whereas the percentage of bugs that fed on dogs rose from 39 to 45-57%, on chickens from 8 to 40-54%, and on cats from 7 to 12-23%. Bugs that fed on goat-sheep (2%) were collected mostly from 1 house. In winter, most bugs fed on humans only (48%), followed by dogs only (13%), cats only, or chickens only (approximately 1%). In spring-summer, the percentages of bugs that fed exclusively on humans (19%), dogs (16%), or chickens (17%) were similar. The seasonal shift was associated closely with changes in the sleeping places of people from indoors in winter to verandahs in summer, and with the presence of brooding hens or ducks in or close to bedrooms in spring-summer. In spring-summer, at each instar, bugs had more identified blood meals, switched hosts from earlier instars, fed on a larger number of different host types, and took mixed meals more frequently than in winter. Bugs collected from walls, roofs and household goods showed similar blood-feeding patterns, whereas bugs from beds showed the highest frequency of human meals. The increased anthropophagy of domiciliary T. infestans populations at the end of winter and during spring precedes or coincides with the spring peak incidence of acute cases of Chagas disease in the region. This is the 1st report documenting seasonal variation in host selection of any triatomine species.

Animals↗
PubMed1996

Probability of infection with Trypanosoma cruzi of the vector Triatoma infestans fed on infected humans and dogs in northwest Argentina.

The probability that an uninfected Triatoma infestans would become infected with Trypanosoma cruzi after a single feed on people or dogs seropositive for T. cruzi was estimated in Amama, a rural village in northwest Argentina where transmission had resurged four years earlier. The prevalence of seropositivity for T. cruzi was 34.2% among 225 people tested, and 65.1% among 83 dogs tested. Parasitemia was detected by xenodiagnosis in 29.3% of 41 seropositive persons and in 85.3% of 34 seropositive dogs. Parasitemia decreased with age more sharply in seropositive people than in seropositive dogs. Seropositive humans infected 2.6% (95% confidence interval = 1.6%-3.6%) of 963 third or fourth instar nymphs fed once on them, whereas dogs infected 48.7% (44.7%-52.7%) of 610 nymphs. The probability of bug infection increased significantly with instar and was positively related to molting success. The infectivity to bugs of seropositive dogs was 12 times higher than that of seropositive children, and 100 times higher than that of seropositive adults. The weighted probability of infection of an uninfected bug fed randomly on any dog (0.3082) was about 50 times higher than that of bugs fed on any human (0.0062). Such differences in relative infectivity, combined with the relative host-feeding preference of domiciliary Triatoma infestans for dogs, reinforces the important role of domestic dogs as a risk factor for the domestic transmission of T. cruzi.

Adolescent↗
PubMed1995

Detecting domestic vectors of Chagas disease: a comparative trial of six methods in north-west Argentina.

Six methods for detecting domestic infestations by triatomine bugs were compared in the rural community of Amamá, north-west Argentina. An average of three pairs (range, 2-5 pairs) of sensor boxes and sheets of pink typing-paper were tacked to the walls of human sleeping areas in 45 houses for 30 days and then inspected by a two-man team. Triatoma infestans bugs were collected in bedrooms by a different two-man team aided by a flushing-out agent both before and after application of sensing devices. Finally, knockdown collections of bugs after application of one insecticide fumigant canister per bedroom were also made. The proportion of houses with evidence of current domestic bug infestations that were detected by the various methods were as follows: sensor boxes (95.3%), reports of householders (88.4%), knockdown (87.8%), paper-sheets (86.0%), and flushing-out (69.8-76.7%). The detectability of infestations, irrespective of the method used, increased with the density of the bugs. At low or intermediate bug densities, individual sensor boxes were more sensitive than their matched paper-sheets, but at any bug density there were no significant differences between the pooled results for all the boxes and for all the paper-sheets in the house. On average, each sensor box recorded 2.25 times more triatomine faecal smears than its matched paper-sheet, and this relation increased with the density of bugs in the house. Both sensing devices were effective at monitoring unsuccessful attempts of peridomestic triatomine populations to colonize houses.

Animals↗
PubMed1993

Comparison of two sampling methods for domestic populations of Triatoma infestans in north-west Argentina.

In mud-and-thatch houses of Santiago del Estero Province, north-west Argentina, where no insecticides had been sprayed officially to control domestic infestations of the Chagas disease vector Triatoma infestans (Klug) (Hemiptera: Reduviidae), two knockdown (KD) insecticidal collection procedures were compared with the standard flush-out (FO) method for sampling T. infestans. Bugs were collected by FO using 0.2% tetramethrin in bedrooms of (1) 41 houses of Amamá village employing 1 man-hour of capture effort per house, and (2) 19 houses of Trinidad and Mercedes villages employing 4 man-hours/house. From the same houses, 2-5 days after the manual FO collection, bugs were collected by KD indoor-spraying of deltamethrin 25 mg a.i./m2 in Amamá, or burning of one gamma-HCH (= gamma-BHC) fumigant tablet 3.1 g of gamma-isomer) per bedroom in Trinidad and Mercedes. The majority of infestations were detected by both methods, the proportion of positive houses being 81% at Amamá and 95% at the other villages. Although the FO method was more sensitive, at least because it was applied first, the KD method detected infestations in 25% of houses where bugs were not found by FO. Bug densities estimated by FO or by subsequent KD in each house were significantly correlated: r = 0.795 for deltamethrin; r = 0.882 for gamma-HCH. Compared with FO collections of T. infestans large stages, i.e. adults plus fourth and fifth instar nymphs, the KD catch averaged 0.88 x with deltamethrin and 0.57 x with gamma-HCH, regardless of the apparent population density of bugs per house. However, the KD method has practical advantages of speed and standardization.

Animals↗