Selective Insecticide Applications Directed Against Triatoma infestans (Hemiptera: Reduviidae) Affected a Nontarget Secondary Vector of Chagas Disease, Triatoma garciabesi.

The control of nondomiciliated triatomine species adapted to peridomestic habitats represents a challenge because they are connected to sylvatic colonies, and pyrethroid insecticides have limited effects outdoors. The effects of residual insecticide spraying have rarely been assessed on secondary triatomines. Triatoma garciabesi (Carcavallo, Martinez, Cichero, Prosen & Ronderos, 1967) is a nontarget vector that inhabits the dry western Chaco region, and a member of the Triatoma sordida Stål 1859 complex. Little is known on the capacity of T. garciabesi to invade and establish viable domestic or peridomestic colonies, and on its response to residual insecticide sprays directed against Triatoma infestans Klug 1834. The presence and abundance of triatomines were assessed by timed manual collections annually or biannually (spring and fall) during 10 yr after a community-wide insecticide spraying campaign and selective insecticide sprays directed against T. infestans in a rural village of northwestern Argentina. T. garciabesi mainly occupied peridomestic habitats associated with chickens, and was unable to colonize human sleeping quarters. Trees with chickens occurred in nearly all houses and were infested in >25% of the occasions. The abundance of bugs at house-compound level was best explained by a generalized estimating equation model that included selective insecticide sprays during the previous semester (negative effects), chicken abundance (positive effects), seasonality, and their interactions. Our results suggest that insecticide applications targeting T. infestans affected the abundance of T. garciabesi, and reduced the likelihood of future infestation.

Two sticky traps baited with synthetic host odors to capture Triatoma infestans, an important vector of Chagas disease.

Chagas disease is a vector-borne disease caused by Trypanosoma cruzi, which is transmitted by triatomine insects. Triatoma infestans is one of the main vectors. Efforts to eliminate T. infestans have often failed in the Gran Chaco, the largest endemic area of this species. Known methods for assessing triatomine house infestation include timed-manual collections by skilled personnel, bug notifications by householders' and/or non-baited detection devices. However, the detection sensitivity of those methods needs to be improved, especially when the bugs are present at low densities. In this work we design and evaluate the performance of two types of sticky traps (pitfall and climbing traps), when baited with a synthetic host odor lure, to capture T. infestans nymphs within an experimental box under semi-controlled laboratory conditions. Nine assays were conducted for each type of trap using a different experimental box per type of trap design and per treatment. These treatments were: test (T, trap baited with the synthetic lure), positive control (C+, trap baited with a mouse) and negative control (C-, empty trap). One hundred percent of the sticky pitfall and 89% of the climbing traps baited with the synthetic lure captured at least one insect. Moreover, the sticky pitfall trap and the sticky climbing trap, both baited with the synthetic lure, captured 30% and 40% of the insects in a single night, respectively. In both cases, the trap with the synthetic lure captured significantly more insects than the non-baited trap. However, the synthetic lure could be improved, as the traps with this lure captured significantly less insects than the traps with a live host. In summary, the two types of synthetically-baited traps tested were able to capture T. infestans nymphs, indicating that both designs are effective under the laboratory experimental conditions and insect abundance used in this work. These traps deserve to be tested in a field setting.

Environmental and demographic factors determining the spatial distribution of Triatoma guasayana in peridomestic and semi-sylvatic habitats of rural northwestern Argentina.

Triatoma guasayana (Wygodzinsky & Abalos), a sylvatic vector of Chagas' disease, occurs in natural and peridomestic habitats of the dry Chaco region of Argentina, Bolivia and Paraguay. Ten-year retrospective spatial analyses of peridomestic T. guasayana abundance in the rural community of Amamá were expanded to the neighbouring community of Trinidad in northwestern Argentina. The distribution of T. guasayana in domiciles, peridomiciles (storerooms, chicken coops and corrals) and natural habitats (bromeliads, dry cacti and logs) around houses (i.e. 'semi-sylvatic' habitats) was analysed. The distribution of the 316 T. guasayana specimens collected in domestic and peridomestic sites during 1993-2002 was significantly clustered in both communities. Searches confirmed that the spatial distribution of semi-sylvatic and peridomestic T. guasayana was determined by the joint effects of the local abundance of goats and the density of semi-sylvatic habitats. The integration of detailed entomological and demographic longitudinal data with geographic information system data, high-resolution satellite imagery, appropriate spatial and temporal analyses and field observations allowed us to infer the underlying processes determining the distribution of T. guasayana in rural communities. This approach may be applied to other sylvatic and peridomestic vectors of Chagas' disease in order to identify high-risk areas for targeted control or environmental management.

Host-Feeding Sources and Infection With Trypanosoma cruzi of Triatoma infestans and Triatoma eratyrusiformis (Hemiptera: Reduviidae) From the Calchaqui Valleys in Northwestern Argentina.

We assessed the prevalence of infection with Trypanosoma cruzi, parasite genotypes (discrete typing units, DTUs), and the host-feeding sources of domestic and peridomestic Triatoma infestans Klug and Triatoma eratyrusiformis Del Ponte in eight rural communities of the subandean Calchaqui valleys in northwestern Argentina. We sought to analyze their epidemiological role in the context of routine vector surveillance and control actions. Infection with T. cruzi was determined by optic microscopy or polymerase chain reaction (PCR) amplification of the hypervariable region of kinetoplast DNA minicircles. Parasite genotypes were identified through a multi PCR-based strategy. Bloodmeal contents were tested with a direct ELISA assay against nine antisera. Human sleeping quarters (domiciles) and peridomestic dry-shrub fences concentrated most of the T. infestans and T. eratyrusiformis infected with T. cruzi, respectively. The most frequent host-feeding sources of T. infestans were chickens (73.1%) in peridomiciles and humans (73.3%) in domiciles, whereas T. eratyrusiformis fed more often on cavid rodents (92.6%), which thrived in the dry-shrub fences. The main T. cruzi DTU identified in both vectors was T. cruzi I (TcI). Triatoma eratyrusiformis was implicated in the local circulation of TcI among cavies and perhaps mice, but infection with other typically domestic DTUs (TcVI and TcII/TcV/TcVI) indicated overlap between (peri)domestic transmission cycles in both vector species. Because dry-shrub fences were not targeted for routine insecticide spraying, they may act as sources of (peri)domestic reinfestation. Triatoma eratyrusiformis is an emergent secondary vector of T. cruzi and plays a significant role in the local transmission of T. cruzi.

Feeding rates, nutritional status and flight dispersal potential of peridomestic populations of Triatomainfestans in rural northwestern Argentina.

Triatoma infestans, the main vector of Chagas disease in Southern Cone countries, frequently infests peridomestic structures housing domestic animals. A total of 814 T. infestans collected from 35 different peridomestic sites in rural northwestern Argentina over 1-4 consecutive seasons was examined for recent blood meals and nutritional status. Bugs from goat or pig corrals had lower qualitative nutritional status and mean weight to length ratios (W/L) than those captured in chicken coops. Males systematically had lower qualitative nutritional status and W/L than females. Using logistic multiple regression, the daily feeding rates of T. infestans were significantly associated with season and stage but not ecotope, whereas the proportion of well-fed bugs varied significantly with all three factors. The seasonal trends in feeding rates and nutritional status were consistent with the local availability and breeding timing of domestic animals. The observed data fed into an empirical model predicted that the probability of flight initiation would peak in summer from pig or goat corrals, not chicken coops, and be insignificant in all ecotopes in spring and fall. Male T. infestans outnumbered females as potential fliers. This is the first study conducted in well-defined habitat units that shows significant heterogeneities in the feeding rates and nutritional status of triatomine populations linked to host demographics and management, and how these affect flight dispersal potential over seasons. Peridomestic bug populations are of great relevance as a source of domestic reinfestation and for the elimination of T. infestans.

Microcavia australis (Caviidae, Rodentia), a new highly competent host of Trypanosoma cruzi I in rural communities of northwestern Argentina.

Rodents are well-known hosts of Trypanosoma cruzi but little is known on the role of some caviomorph rodents. We assessed the occurrence and prevalence of T. cruzi infection in Microcavia australis ("southern mountain, desert or small cavy") and its infectiousness to the vector Triatoma infestans in four rural communities of Tafí del Valle department, northwestern Argentina. Parasite detection was performed by xenodiagnosis and polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR) from blood samples. A total of 51 cavies was captured in traps set up along cavy paths in peridomestic dry-shrub fences located between 25 and 85 m from the nearest domicile. We document the first record of M. australis naturally infected by T. cruzi. Cavies presented a very high prevalence of infection (46.3%; 95% confidence interval, CI=33.0-59.6%). Only one (4%) of 23 cavies negative by xenodiagnosis was found infected by kDNA-PCR. TcI was the only discrete typing unit identified in 12 cavies with a positive xenodiagnosis. The infectiousness to T. infestans of cavies positive by xenodiagnosis or kDNA-PCR was very high (mean, 55.8%; CI=48.4-63.1%) and exceeded 80% in 44% of the hosts. Cavies are highly-competent hosts of T. cruzi in peridomestic habitats near human dwellings in rural communities of Tucumán province in northwestern Argentina.

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.

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.

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.

Chagas disease in north-west Argentina: association between Trypanosoma cruzi parasitaemia in dogs and cats and infection rates in domestic Triatoma infestans.

The association between Trypanosoma cruzi parasitaemia in dogs and cats and Tryp. cruzi infection rates in domestic Triatoma infestans was studied in a cross-sectional survey of 31 houses (89%) in the rural villages of Trinidad and Mercedes, north-west Argentina, where no spraying of insecticides had ever been done. Similar prevalence rates of parasitaemia, determined by xenodiagnosis, were recorded among 68 dogs (41.2%) and 28 cats (39.3%). Bug infection rates were significantly associated with the presence of infected cats (those with positive xenodiagnosis) stratified by the number of infected dogs (relative risk = RR = 1.90; 95% confidence interval = CI = 1.51-2.38), and with the number of infected dogs stratified by the presence of infected cats (RR = 2.71; CI = 1.81-4.07). The percentage of infected bugs in houses with and without children stratified by the presence of infected dogs or cats was not significantly different (RR = 0.69; CI = 0.45-1.05). The combined effect of infected dogs and infected cats on bug infection rates fitted closely with an additive transmission model. Bug infection rates were significantly higher when infected dogs shared the sleeping areas of people than when they did not (RR = 1.79; CI = 1.1-2.91). Our study showed that infected dogs and infected cats increase the risk of domestic transmission of Tryp. cruzi to T. infestans.

Chagas disease in north-west Argentina: risk of domestic reinfestation by Triatoma infestans after a single community-wide application of deltamethrin.

The risk of domestic reinfestation by Triatoma infestans after a single community-wide application of delta-methrin (2.5% suspension concentrate at 25 mg active ingredient/m2) was studied in Amamá, north-west Argentina, where no insecticide spraying had been done by official control services. The percentage of infested houses fell from 88% before spraying in 1985 to nil during the 6 months after spraying, and thereafter increased from 5% in 1986 to 96% before a second treatment in 1992, fitting closely to a logistic model (r2 = 0.997). Significant risk factors associated with domestic reinfestation determined from stepwise logistic regression and one-factor analysis were the density of T. infestans in bedrooms just before spraying and the surface structure of indoor walls. Peak densities of bugs in 1988-1989 significantly differed between levels of both risk factors. Our study suggests the existence of stable determinants of infestation linked to the household which, in the absence of effective control measures, would also determine the speed of house recolonization and the ensuing bug densities. Plastering of mud walls before application of insecticides to all domestic and peridomestic structures is supported by the study.

Chagas disease in north-west Argentina: infected dogs as a risk factor for the domestic transmission of Trypanosoma cruzi.

The association between household seroreactivity to Trypanosoma cruzi in dogs and children and T. cruzi infection rates in domestic Triatoma infestans was investigated in 1988-1989 in the rural community of Amamá, north-west Argentina, where house spraying with residual pyrethroids was carried out in 1985. Three years after spraying, a greater reduction of the average T. cruzi prevalence rate in dogs (from 83% to 40%) than in children (from 48% to 30%) was accompanied by a substantial decrease in vector infection rates from 51%-63% to 21%. At a household level, in homes with or without seroreactive children, the percentage of infected T. infestans was 4.5-4.7 times higher when seroreactive dogs were present (27.1%-34.8%) than when they were not (5.8%-7.7%; stratified relative risk [RR] = 4.58). The contribution of seroreactive children to bug infection rates was not significant (RR = 1.29). The combined effect of both seroreactive dogs and seroreactive children fitted equally well with additive or multiplicative transmission models. Bug infection rates showed an increasing trend with the number of seroreactive dogs and an inverse association with the age of the youngest seroreactive dog. Our study supports the hypothesis of a causal association between the presence and number of infected dogs and increased levels of T. cruzi transmission to domestic T. infestans.

Seasonal variations of microclimatic conditions in domestic and peridomestic habitats of Triatoma infestans in rural northwest Argentina.

Our objectives were to describe and compare the seasonal variations in microclimatic conditions in domestic and peridomestic ecotopes infested by Triatoma infestans, the main vector of Chagas disease, in rural northwestern Argentina. Using data loggers for 4-7 consecutive days in October 2000, February, May and August 2001, microsite (interior of thatched roofs) and ambient temperatures or relative humidity (RH) were recorded simultaneously and compared with an external reference. The damping effects on microsite temperature and ambient RH increased successively from the goat corral to the chicken coop or pig corral, to the storeroom or human habitation. In the interior of the thatched roofs of the habitation and storeroom, average external minima were increased by +5.0 to +5.6 degrees C in all seasons, and average external maxima were decreased by -4.3 to -5.6 degrees C in October-May and -10.6 degrees C in August. On average, the human habitation damped extreme temperatures by 8 degrees C over a wider range than previously reported. The interior of the thatched roofs of the pig corral and chicken coop exerted intermediate damping effects that varied over seasons, whereas the goat corral's thatch showed little or no damping effects at all. The adobe-and-thatch habitation and storeroom presented nearly optimal and more suitable conditions for T. infestans populations than other open structures housing animals. Global climate changes are expected to affect peridomestic populations of T. infestans much more than domestic bug populations, provided other local conditions are held constant. Heterogeneous habitat conditions are expected to affect T. infestans population parameters, dispersal, control and infection with Trypanosoma cruzi.

Effects of partial housing improvement and insecticide spraying on the reinfestation dynamics of Triatoma infestans in rural northwestern Argentina.

The long-term effects on domiciliary reinfestation by Triatoma infestans of smoothing the plaster of indoor walls prior to insecticide application (in Amamá village) relative to only insecticide application (in Trinidad-Mercedes villages) were evaluated in rural northwestern Argentina from 1992 to 1997. All domestic and peridomestic areas of each house were sprayed with 2.5% suspension concentrate deltamethrin at 25 mg/m(2) in October 1992, and infestations were assessed by various methods every 6 months. Domiciliary infestation decreased from 72-88% in 1992 to 6-17% in late 1995, to increase moderately thereafter without returning to baseline rates. Peridomestic sites were the first in becoming reinfested, and reached more abundant T. infestans populations than domiciliary areas. Domiciliary infestation rates and bug abundances were not significantly different between communities during surveillance. Domiciliary infestation rates in well-plastered houses were very low (5-9%) and approximately stable until 1996, but in houses with regular or bad plaster they consistently increased from 5 to 19-21% in both communities. Logistic multiple regression analysis showed that the likelihood of domestic infestation assessed through householders' collections was significantly and positively associated with the occurrence of an infested peridomestic site in the respective house, the occurrence of high-density domestic infestations before interventions, and well-plastered walls in 1996. Combining insecticide spraying and partial improvement of walls controlled domestic infestations and transmission of Trypanosoma cruzi effectively, but was not sufficient to eliminate T. infestans from the study area or increase the effectiveness of careful chemical control.

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.

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.

A simple method to identify triatomine (Hemiptera: Reduviidae) feces in sensing devices used in vector surveillance programs.

We successfully applied the phenolphthalin (Kastle-Meyer) test used in forensic chemistry to distinguish between feces from triatomines and other domestic arthropods in sensing devices used for vector surveillance. All black or dark brown, but not white or yellow, fecal smears from laboratory-reared or field-collected Triatoma infestans Klug, Triatoma guasayana Wydgozinsky & Abalos, Triatoma sordida Ståhl (recently revalidated as Triatoma garciabesi Carcavallo, Cichero, Martínez, Prosen & Ronderos) tested positive, whereas dejecta from cockroaches and spiders, crickets, beetles, predatory bugs, and domestic flies tested negative. Black or dark brown dejecta from female Aedes aegypti L. and Cimex lectularius L. bedbugs also tested positive. In sellsing devices installed in bedrooms of 11 houses in Amamá, rural northwestern Argentina, where neither cimicid bedbugs nor argasid ticks had been found over the years, only 62% of the black or dark brown fecal smears attributed to triatomines by a skilled observer tested phenolphthalin-positive. After insecticidal spraying, when bedroom areas were not colonized by triatomines, only 33-40% of the black or dark brown fecal smears in sensor boxes attributed to triatomines by another skilled observer tested phenolphthalin-positive. Eleven (79%) ofthe 14 houses with dubious or nontypical triatomine feces tested phenolphthalin-positive at least once during 1993-1995. Our study introduces a low-cost, simple and effective procedure for the identification of triatomine feces. The test, as a helpful adjunct to sensing devices used in triatomine surveillance, will aid in the accurate detection of infestations and the determination of the need for insecticide application.

Which method for quantifying "microalbuminuria" in diabetics? Comparison of several immunological methods (immunoturbidimetric assay, immunonephelometric assay, radioimmunoassay and two semiquantitative tests) for measurement of albumin in urine.

We have compared the chemical and clinical characteristics of an immunonephelometric assay (INA), two immunoturbidimetric assays (ITA) and two semi-quantitative methods with those of a solid-phase radioimmunoassay (RIA) for measurement of urinary albumin (UA) concentration in 136 diabetic patients. INA and RIA had similar accuracy, and provided comparable results. However, RIA has slightly greater sensitivity than INA, which is easier and faster. Good agreement was also found between RIA and the two ITA methods, although one of these overestimated RIA values in the low-medium range (5-30 mg/l) of urinary albumin. ITA seems suitable for initial screening of albuminuria in diabetic patients but more sensitive procedures (such as RIA and INA) seem preferable for measurement of UA concentrations in the normal range. The two semi-quantitative methods showed high sensitivity but poor specificity, because of the large number of false positive results. About 50% of diabetic patients "positive" by these methods did not have microalbuminuria. The utility of these methods is questionable, because many samples from diabetic patients need to be reassayed by a more specific and sensitive assay such as the RIA, INA or ITA methods.

PIP (Positive Image Program): a group approach for obese adolescents.

This article describes an adolescent weight control program in a hospital ambulatory care center. An interdisciplinary team of members from dietary, medicine, nursing, and physical therapy departments work together to provide a comprehensive approach for improving the body images of young adolescents. Behavior modification, exercise, awareness of nutrition, and individual support are the components of the Positive Image Program. Symbols are used for the introduction of nutritional concepts and for reinforcements throughout the sessions. A progressive exercise program provides concrete evidence of increased tolerance for activity. Lifestyle changes and a positive body image are internalized goals that can only be measured over time. On the basis of the small sample of adolescents in the two groups, no definitive statements can be made concerning the general ability of the P.I.P. group. Follow-up of clients and continued evaluation of the Positive Image Program over time will determine the effectiveness of this approach as a means of adolescent weight control.