Comparison of three residential mosquito traps against riceland mosquitoes in southeast Arkansas.

Field trials were conducted at 3 locations in Arkansas County, AR, to compare the effectiveness of 3 residential mosquito traps, the Stinger Mosquito Vacuum, the Mosquito Magnet Defender, and the Mosquito Deleto 2500 Active System, against riceland mosquitoes, specifically Anopheles quadrimaculatus and Psorophora columbiae. Both the Stinger Mosquito Vacuum and the Mosquito Deleto captured significantly more An. quadrimaculatus and total mosquitoes than did the Mosquito Magnet Defender. The Mosquito Deleto captured significantly more Ps. columbiae than did either of the other 2 traps.

The outcome in the United States after thoracoabdominal aortic aneurysm repair, renal artery bypass, and mesenteric revascularization.

OBJECTIVES: The purpose of this study was to determine outcome and identify predictors of death after thoracoabdominal aortic aneurysm (TAA) repair, renal artery bypass (RAB), and revascularization for chronic mesenteric ischemia (CMI). PATIENTS AND METHODS: In this retrospective analysis, data were obtained from the Nationwide Inpatient Sample, a 20% all-payer stratified sample of hospitals in the United States during 1993 to 1997. Patients were identified by the presence of a diagnostic or procedure code from the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). The main outcomes we examined were death, ICD-9-CM -based complications, length of stay, hospital charges, and disposition. A multivariate model was constructed to predict death. RESULTS: A total of 2934 patients were identified (TAA, 540; RAB, 2058; CMI, 336) in the database. The mean age was comparable (TAA, 69 +/- 9 years; RAB, 66 +/- 12 years; CMI, 66 +/- 11 years), but the breakdown between the sexes varied by procedure (male: TAA, 53%; RAB, 55%; CMI, 24%). The mortality rate (TAA, 20.3%; RAB, 7.1%; CMI, 14.7%), complication rate (TAA, 62.2%; RAB, 37.4%; CMI, 44.6%), and the percentage of patients discharged to another institution (TAA, 21.2%; RAB, 9.3%; CMI, 12.0%) were clinically significant for all procedures. The mortality rate for RAB was greater when performed concomitant with an aortic reconstruction (4.4% vs 8.3%). All three procedures were resource intensive as reflected by the median length of stay (TAA, 14 days; RAB, 9 days; CMI, 14 days) and median hospital charges (TAA, $64,493; RAB, $36,830; CMI, $47,390). The multivariate model identified several variables for each procedure that had an impact on the predicted mortality rate (TAA, 14%-76%; RAB, < 1%-46%; CMI, < 2%-87%). CONCLUSIONS: The operative mortality rates across the United States for patients undergoing TAA repair and RAB are greater than commonly reported in the literature and mandate reexamining the treatment strategies for these complex vascular problems.

Experience in the United States with intact abdominal aortic aneurysm repair.

OBJECTIVES: The purpose of this study was to determine the current outcome in the United States and to identify predictors of mortality and "bad outcome" after open, intact abdominal aortic aneurysm (AAA) repair. METHODS: In a retrospective analysis, data were obtained from the Nationwide Inpatient Sample during 1994-1996. The Nationwide Inpatient Sample is a 20% all-payer stratified sample of nonfederal United States hospitals. Patients older than 49 years were identified by the presence of primary diagnostic (441.4-intact AAA) and procedure (38.44-resection of abdominal aorta with replacement) codes of the International Classification of Diseases, Ninth Revision (ICD-9 ). In-hospital mortality rate, discharge disposition, bad outcome (death or discharge to an institution), complications (ICD-9 postoperative codes), length of stay, and charges were determined. The mortality rate and bad outcome were analyzed by the use of patient demographics (age, sex, race), patient comorbidities (ICD-9 diagnostic codes), calendar year, and hospital characteristics (size, location, teaching status) with univariate and multivariate analyses. RESULTS: We identified 16,450 intact AAAs repairs during the study years. The mean patient age was 72 +/- 7 (+/- SD) years, and most patients were male (79.7%) and white (94.6%). Most repairs were performed at large (67.3%), urban (92.5%), and nonteaching (66.7%) institutions. The in-hospital mortality rate was 4.2%, the overall complication rate was 32.4%, and 91.2% of patients were discharged home, whereas the bad outcome rate was 12.6%. The median length of stay was 8 days (mean, 10.0 +/- 8.1), and median hospital charges were $28,052 (mean, $35,681 +/- $33,006) in 1996 dollars. Multivariate analysis showed that the mortality rate (P <.05) increased with age (70-79 years, 1.8 odds ratio [OR] [95% CI, 1.4-2.3], > 79 years, 3.8 OR [95% CI, 2.9-4.9]), sex (female, 1.6 OR [95% CI, 1.3-1.9]), cerebral vascular occlusive disease (1.8 OR [95% CI, 1.3-2.5]), preoperative renal insufficiency (9.5 OR [95% CI, 7.7-11.7]), and more than three comorbidities (11.2 OR [95% CI, 3.6-35.4]). Multivariate analysis also showed that bad outcome was associated with the same variables in addition to hospital size (small/medium), year of procedure (1996), chronic obstructive pulmonary disease, and two to three comorbidities. CONCLUSIONS: Outcome after open repair of intact AAA across the United States is quite good. Older, sicker patients may benefit from nonoperative treatment or the potentially lower risk endovascular approaches.

Impact of race on the treatment for peripheral arterial occlusive disease.

PURPOSE: The purpose of this study was to determine the impact of race on the treatment of peripheral artery occlusive disease (PAOD) and to examine the role of access to care and disease distribution on the observed racial disparity. METHODS: The study was performed as a retrospective analysis of hospital discharge abstracts from 1992 to 1995 in 202 non-federal, acute-care hospitals in the state of Florida. The subjects were patients older than 44 years of age who underwent major lower extremity amputation or revascularization (bypass grafting or angioplasty) for PAOD. The main outcome measures were incidence of intervention, incidence per demographic group, multivariate predictors of amputation versus revascularization, multivariate predictors of amputation versus revascularization among those patients with access to sophisticated care (hospital with arteriographic capabilities), and multivariate predictors of surgical bypass graft type (aortoiliac vs infrainguinal). RESULTS: A total of 51,819 procedures (9.1 per 10,000 population) were performed for PAOD during the study period and included 15,579 major lower extremity amputations (30.1%) and 36,240 revascularizations (69.9%). Although the incidence of a procedure for PAOD was comparable between African Americans and whites (9.0 vs 9.6 per 10, 000 demographic group), the incidence of amputation (5.0 vs 2.5 per 10,000 demographic group) was higher and the incidence of revascularization (4.0 vs 7.1 per 10,000 demographic group) was lower among African Americans. Furthermore, multivariate analysis results showed that African Americans (odds ratio, 3.79; 95% confidence interval [CI], 3.34 to 4.30) were significantly more likely than whites to undergo amputation as opposed to revascularization. The secondary multivariate analyses results revealed that African Americans (odds ratio, 2.29; 95% CI, 1.58 to 3. 33) were more likely to undergo amputation among those patients (n = 9193) who underwent arteriography during the procedural admission and to undergo infrainguinal bypass grafting (odds ratio, 2.00; 95% CI, 1.48 to 2.71) among those patients (n = 27,796) who underwent surgical bypass grafting. CONCLUSION: There is a marked racial disparity in the treatment of patients with PAOD that may be caused in part by differences in the severity of disease or disease distribution.

Mosquito (Aedes taeniorhynchus) resistance to methoprene in an isolated habitat.

Salt-marsh mosquitoes (Aedes taeniorhynchus), collected on 2 barrier islands in Lee County, Florida, that had been treated from 1989 to 1994 with 150-day methoprene briquets, were bioassayed with technical s-methoprene in the laboratory. Susceptibility of the indigenous Captiva strain (median lethal concentration [LC50] estimate, 6.71 ppb) collected from Captiva Island was 14.9-fold lower than the naive Flamingo strain (LC50 estimate, 0.45 ppb) from Everglades National Park. The Lover's Key strain (LC50 estimate, 6.66 ppb) was 14.8-fold less susceptible than the naive strain. Determinations of the susceptibility of nearby foci of the mainland mosquitoes exposed in the past several years to methoprene have not been completed, but probit analysis of laboratory exposures revealed that the only mainland strain tested (Burnt Store) was no less susceptible (1.06-fold) than the naive Flamingo strain. These findings support the theory that the observed resistance might be restricted to the barrier islands. The known resistance foci (generated with briquet formulations) are located west of the mainland where there is minimal likelihood of inflow of genome from the mainland. On the other hand, the mainland mosquitoes, which were exposed to liquid formulations of methoprene from 1987 to 1994, are believed to have substantial gene flow between exposed and nonexposed populations and thus a reduced likelihood of selection for resistance.

Effect of the Asymptomatic Carotid Atherosclerosis Study on carotid endarterectomy in Florida.

BACKGROUND AND PURPOSE: The value of carotid endarterectomy (CEA) has been defined by several recent multicenter trials. The clinical effect of these trials remains undetermined since the Asymptomatic Carotid Atherosclerosis Study (ACAS) Clinical Advisory (dated September 28, 1994). METHODS: Patients undergoing CEA (ICD-9-CM 38.12) in nonfederal Florida hospitals were identified from the discharge database. Data were analyzed by federal fiscal year (FY, October 1 through September 30), comparing the years following the Advisory (FY95-FY96) to the preceding 3 years (FY92-FY94). RESULTS: There was a 68.3% increase in the number of CEAs during FY95-FY96 (mean FY92-FY94, 7,343; mean FY95-FY96, 12,356). This exceeded increases in total hospital discharges (4.5%), surgical discharges (2.2%), and the state's population (4.7%). The increase in CEAs spanned all patient demographic groups (gender, race, and age), although the magnitude was not consistent (range, 57.8% increase for 55 to 64 age group; 92.9% increase for > 84 age group). Concomitantly, there was a significant decrease in mortality (1.2% versus 0.8%), cardiac complication rate (ICD-9-CM 997.1, 4.1% versus 3.0%) and percentage of patients discharged > 7 days postoperatively (8.9% versus 4.9%). Mean length of stay declined 28% (5.8 versus 4.1 days), and mean adjusted charges declined 7% ($19,456 versus $18,055). Although the average case was less costly, the increased volume resulted in an estimated $56 million increase in annual hospital payments. CONCLUSIONS: The dramatic increase in the number of CEAs performed in the state of Florida after release of the ACAS Clinical Advisory suggests a causal relationship and mandates further cost-effectiveness analyses.

Efficacy of three synthetic pyrethroids against three mosquito species in Arkansas and Louisiana.

Adult mortality of Anopheles quadrimaculatus, Culex quinquefasciatus, and Aedes sollicitans was observed following ultra-low-volume (ULV) exposure to Responde, Permanone 31-66 RTU, and Scourge. Permanone 31-66 RTU (1:2.13, permethrin:PBO) and Scourge (1:3, resmethrin:PBO) were applied at 0.00175 lb AI/acre, while Responde (1:3, prallethrin:PBO) was applied at 0.001 lb AI/acre, and all were evaluated at 100, 200, and 300 ft. downwind of application. Significant mortality differences (P < or = 0.05) were observed among all compounds at 15 min and at 1, 12, and 24 h posttreatment against An. quadrimaculatus and Cx. quinquefasciatus. Responde exhibited significantly greater (P < or = 0.05) control (knockdown) against An. quadrimaculatus at both 15 min and 1 h posttreatment than did Permanone 31-66 RTU or Scourge; however, some recovery occurred by 12 h posttreatment. At 15 min posttreatment, Responde and Scourge were significantly (P < or = 0.05) more effective against Cx. quinquefasciatus than Permanone 31-66 RTU except at 300 ft. downwind, where Scourge was significantly (P < or = 0.05) more effective than either compound. No significant mortality differences (P < or = 0.05) were observed among the 3 compounds at 15 min, 1 h, 12 h, and 24 h posttreatment when tested against Ae. sollicitans. No significant mortality differences (P < or = 0.05) were observed between the 1:3 and 1:5 (prallethrin: piperonyl butoxide) formulations of Responde at any time posttreatment when tested against Ae. sollicitans.

Control of Aedes albopictus in waste tire piles with reduced rates of temephos-treated granules.

Two days following treatment, larval populations of Aedes albopictus in waste tires treated with granular formulations of temephos were reduced 90% at the 0.11 kg AI/ha rate, 98% at the 0.56 kg AI/ha rate, and 100% at the 1.12, 11.21, and 22.42 kg AI/ha rates. Nearly 100% control was achieved for 8 wk at the 0.5 kg AI/ha rate, for 7 wk at the 1.12 kg AI/ha rate in one replicate, and for at least 5 months at the 11.21 and 22.42 kg AI/ha rates. These results indicate that prolonged control can be achieved with granular formulations at half (11.21 kg/ha) the maximum label rate and that excellent immediate control can be expected at 2.5% the maximum label rate.

Assessment of Anopheles quadrimaculatus response to permethrin and resmethrin by topical application.

Topical applications with field-captured mosquitoes provided LD50 estimates ranging from 13.3 to 20.0 ppm for permethrin and 8.5 to 18.9 ppm for resmethrin in the Stuttgart, AR, area in 1993. Mosquitoes collected from the abatement area appeared to be more susceptible to resmethrin than those from outside the area (8.5 ppm vs. 18.9 ppm). The observed difference was not great enough to be of concern from an economic or control standpoint. The data provided a firm baseline for future assessment of changes in susceptibility to these 2 materials. Mosquitoes collected in Walnut Ridge, AR, were susceptible to permethrin and resmethrin within the same range as the Stuttgart populations, but the limited number of observations preclude firm LD50 estimates.

Efficacy of various ground-applied cold aerosol adulticides against Anopheles quadrimaculatus.

Ground-applied ULV, cold aerosol insecticides were tested against adult female Anopheles quadrimaculatus. Treatments included high (H) and low (L) rates of Permanone (permethrin), bioresmethrin and esbiothrin. Malathion was applied as a standard. Mortality at 24-h posttreatment was highest with Bioresmethrin H at 15 m. Permanone H exhibited good control out to 60 m (88.9%), but dropped to an unacceptable level (65.5%) at 90 m. The low rates of all compounds produced unsatisfactory results at 24-h posttreatment. Recovery from knockdown occurred in all treatments with the exception of malathion.

Activity of lambda-cyhalothrin applied as an ultralow volume ground treatment against Anopheles quadrimaculatus adults.

Lambda-cyhalothrin was evaluated as an ultralow volume ground adulticide treatment at rates of 0.25, 0.5 and 1.0 g/ha. Resmethrin, a standard adulticide, was applied at a rate of 1.96 g/ha. All treatments provided greater than or equal to 95% control up to 50 m from the spray route. The highest rate of lambda-cyhalothrin and the resmethrin standard provided greater than or equal to 95% control up to 200 m, which is twice the distance normally assessed in this type of testing. Control was reduced at 200 m for the 0.25 and 0.5 g/ha rates of lambda-cyhalothrin, which provided 73 and 88% mortality, respectively. Lambda-cyhalothrin appears to have the insecticidal activity required for operational mosquito control.

Evaluation of 1-octen-3-ol and carbon dioxide as attractants for mosquitoes associated with irrigated rice fields in Arkansas.

Field studies were conducted to determine the responses of mosquitoes associated with irrigated riceland in Arkansas to 1-octen-3-ol (octenol), carbon dioxide (CO2) and combinations of both. Octenol was released at 4.1 (wick in) and 41.1 (wick out) mg/h and CO2 at 200, 500 and 1,000 ml/min. Octenol alone did not result in a significant (P greater than 0.05) increased response for any species relative to unbaited traps. An increase in CO2 release rate generally resulted in an increase in collection size. All octenol + CO2 combinations increased the collections of Coquillettidia perturbans, Culex salinarius and Psorophora columbiae relative to equivalent CO2 release rates alone. Mixed responses for these same treatment combinations were obtained for Anopheles crucians, An. quadrimaculatus and Cx. erraticus.

Elf for electronic linear flow control of variable speed ground ULV applications.

The Elf device delivered the appropriate ground ULV rate at variable road speeds ranging from 4 to 21 mph (6 to 32 kph), and shut off automatically at higher and lower speeds. The system is designed to be compatible with vehicles equipped with digital as well as standard speedometers and can be calibrated at any speed within its operating range. Although not used in these studies, Elf has a distance calibration feature designed to enhance the accuracy of the transducer and thus to yield greater flow precision than could be achieved with the transducer alone.

The effect of Bacillus sphaericus upon the susceptibility of Anopheles quadrimaculatus to Plasmodium berghei.

Larvae of Anopheles quadrimaculatus were exposed to Bacillus sphaericus. The surviving adults took blood meals on hamsters infected with Plasmodium berghei. Fewer mosquitoes were infected than were the paired controls. The inhibitory action appeared to occur during the early stages of the infection in the mosquito gut.

Rearing Dictya floridensis (Diptera: Sciomyzidae) in a continuously producing colony and evaluation of larval food sources.

Methods for large-scale continuous propagation of Dictya floridensis Steyskal were developed. A colony originating from 22 specimens of several Dictya species collected in Alachua County, Fla., became a single species colony after several generations because of failure of all but D. floridensis to survive colonization. The colony was maintained as separate generations until the F5, after which new D. floridensis adults were pooled into mass colony cages. During the F7 generation, colony production was in excess of 1,000 neonate larvae per day, the number of adults was continually increasing, and the females had extended longevity and fecundity. At that time, the colony was considered to be continuously producing, and size of the colony was limited only by the availability of food and rearing facilities. Larvae were reared on living, freshly crushed, frozen snails, Physella hendersoni hendersoni (Clench) and Pseudosuccinea columella Say. Larval development and their survival rate to pupariation was the same whether reared on freshly crushed snails or on live food. Larvae reared on frozen snail tissue compared with live snails had the same sex ratio but were lighter in weight and had extended development time to pupariation and lowered survival rates. Larvae fed and developed successfully upon living embryonated snail egg masses but were unable to use egg masses that had been frozen.

Residual activity of permethrin on cattle as determined by mosquito bioassays.

The residual effectiveness against laboratory-reared female Anopheles quadrimaculatus mosquitoes of a synthetic pyrethroid (permethrin) applied to cattle was determined. Twenty-four-hour postexposure mortality and the degree of successful blood engorgement were determined by exposing mosquitoes for 10 min to cattle. Three replicated assays were conducted and mortality determined at 1, 2, 5, 7, 14 and 21 days after each treatment with an oil-based formulation of permethrin (DeLice) or with an emulsifiable concentrate (Atroban) applied at label rates. Mosquito mortality ranged from 79 to 85% (1 day postapplication) to 12-38% (21 days postapplication).