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1.
Am J Manag Care ; 7(2): 125-30, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11216330

ABSTRACT

OBJECTIVE: To ascertain factors related to readiness to change behavioral risk factors in members of a managed care organization (MCO). STUDY DESIGN: Cross-sectional study. PATIENTS AND METHODS: A telephone survey reached 4667 (73%) of 6409 adult members of a Minnesota MCO attending 2 primary care clinics. Of these, 3826 members (82%) completed an interview designed to identify behavioral risk factors (smoking, consuming a high-fat diet, and physical inactivity) and readiness to change these behaviors. RESULTS: Among MCO members consuming a high-fat diet, those most ready to change were older, were women, used more preventive services, and reported receiving professional advice about diet. For physical inactivity, those most ready to change were younger, women, and more educated; used more preventive services; and reported receiving professional advice about physical activity. Among smokers, those with higher readiness to change smoked fewer than 15 cigarettes a day, had higher self-efficacy, had no other smokers in the household, and reported receiving professional advice about smoking. After controlling for demographic variables and for use of preventive services, greater readiness to change for smoking (beta = 0.336, odds ratio [OR] = 1.40, P = .056), physical activity (beta = 0.651, OR = 1.92, P < .001), and diet (beta = 0.532, OR = 1.70, P < .001) was associated with having received professional advice to change these behaviors. CONCLUSIONS: Levels of readiness to change behaviors in MCO members who smoke, are inactive, or consume high-fat diets are similar to those reported in other populations. The association of professional advice to change behaviors with increased readiness to change for smoking, physical activity, and diet suggests that receiving professional advice on these topics might assist patients in changing adverse health-related behaviors.


Subject(s)
Health Behavior , Health Promotion/statistics & numerical data , Managed Care Programs/statistics & numerical data , Patient Acceptance of Health Care/statistics & numerical data , Adult , Counseling , Cross-Sectional Studies , Dietary Fats , Exercise , Female , Humans , Interviews as Topic , Male , Middle Aged , Minnesota , Professional-Patient Relations , Risk Factors , Smoking Cessation
2.
Eff Clin Pract ; 4(6): 239-49, 2001.
Article in English | MEDLINE | ID: mdl-11769296

ABSTRACT

CONTEXT: Although new strategies for managing depression in primary care (e.g., nurse telephone calls, collaborative care) have been shown to be effective, no models are available for their systematic implementation in the "real world." OBJECTIVE: To test whether a continuous quality improvement (CQI) intervention could be used to implement systems in primary care clinics to improve the care and outcomes for patients diagnosed with depression. DESIGN: Before-after study with concurrent controls. INTERVENTION: A multidisciplinary team from the three intervention clinics developed and implemented a graded set of five care management options, ranging from watchful waiting (nurse telephone call in 4 to 6 weeks) to mental health management, which clinicians could order for their patients with depression. SETTING: 9 primary care clinics in greater Minneapolis-St. Paul, Minnesota. PATIENTS: Outpatients 18 years of age and older whose primary care clinic visit included an International Classification of Diseases, 9th revision, code for depression and who completed baseline and 3-month follow-up surveys before and after the intervention. MAIN OUTCOME MEASURES: Measures of process of care (follow-up depression visits to physician, mental health visits, follow-up telephone calls) and outcomes of care (improved depression symptoms over 3 months, satisfaction with care). RESULTS: Although the CQI team appeared to function well, only 30 of the 257 patients identified from depression-coded visits for this study were referred to the new system during the 3-month evaluation period. In both the intervention and control clinics, follow-up visits, mental health referrals, and follow-up telephone calls did not improve significantly from the preintervention levels of about 0.5 for a primary care visit, 0.4 for a mental health visit, or 0.1 for a follow-up phone call per person. The same was true of patient outcomes: The proportion of patients in the intervention and control clinics who had improved depression symptoms and those who were very satisfied with their depression care did not change significantly from the preintervention levels of 43% and 26%, respectively. CONCLUSIONS: Our attempt to improve the primary care management of depression failed because physicians used the new order system so infrequently. Whether a greater leadership commitment to change or a different improvement process would alter our findings is an open question.


Subject(s)
Depressive Disorder/therapy , Practice Patterns, Physicians' , Primary Health Care/standards , Total Quality Management , Adolescent , Adult , Continuity of Patient Care , Depressive Disorder/classification , Female , Humans , Male , Middle Aged , Minnesota , Outcome and Process Assessment, Health Care , Patient Care Team , Referral and Consultation , Treatment Outcome
3.
Eff Clin Pract ; 4(6): 271-7, 2001.
Article in English | MEDLINE | ID: mdl-11769300

ABSTRACT

CONTEXT: Although universal screening for diabetes mellitus is generally not recommended, recent reports suggest that screening individuals with multiple diabetes risk factors may be worthwhile. Little is known about the cost, yield, or acceptability of this kind of screening. PRACTICE PATTERN EXAMINED: Screening of high-risk patients for diabetes mellitus using a two-step, glucose-based screening protocol: Patients were initially screened with a random glucose test; those with abnormal results received a follow-up fasting, 2-hour, 75-gram oral glucose tolerance test. CLINIC SELECTION: Three volunteer clinics from a large medical group in Minnesota. PATIENT SELECTION: Of 38,989 adults receiving care at the three clinics, we identified 1548 high-risk patients with evidence of both dyslipidemia and hypertension in laboratory and administrative databases. Many of these 1548 patients were not eligible for screening: Twenty-five percent already had diagnosed diabetes; 41% had been screened for diabetes in the past year; and 3% had died, disenrolled, or changed clinics before screening commenced. The remaining 30% (n = 469) were invited for diabetes screening. RESULTS: Of the 469 high-risk patients invited, 206 (44%) initiated screening; 176 (38%) completed diabetes screening. Five new patients with diabetes were identified in this high-risk group (one from the random glucose test and four from the glucose tolerance test). One new patient with diabetes was identified for every 40 high-risk patients screened. The program cost $4064 per new case of diabetes identified (screening costs alone). CONCLUSION: In this high-risk managed care population, the yield and acceptability of systematic diabetes screening were low, and the costs were relatively high. The acceptability of office-based diabetes screening may be improved by using a one-step screening test, such as glycosylated hemoglobin, during routine visits.


Subject(s)
Diabetes Mellitus/diagnosis , Mass Screening/statistics & numerical data , Program Development/economics , Adult , Cost-Benefit Analysis , Diabetes Complications , Diabetes Mellitus/economics , Diabetes Mellitus/epidemiology , Glucose Tolerance Test , Glycated Hemoglobin/analysis , Group Practice/economics , Humans , Hyperlipidemias/complications , Hypertension/complications , Mass Screening/economics , Minnesota/epidemiology , Prevalence , Risk Assessment , Risk Factors
4.
Jt Comm J Qual Improv ; 25(2): 68-77, 1999 Feb.
Article in English | MEDLINE | ID: mdl-10027112

ABSTRACT

BACKGROUND: A worsening of blood pressure control has occurred in the 1990s despite the availability of sophisticated technologic, pharmacologic, and educational advances applicable to hypertension care. Clinical guidelines that are intended to improve hypertension care by making specific recommendations on drug use, frequency of follow-up care, and target levels of blood pressure have been developed. METHODS: The Institute for Clinical Systems Integration's (ICSI's; Minneapolis) Hypertension Treatment Guideline was developed in 1994 and is updated annually. This study employed a quasi-experimental, before-and-after design at two medical groups to assess changes in the care provided to patients 18 years of age and older with identified hypertension (International Classification of Diseases-9 codes 401.0, 401.1, or 401.9). RESULTS: Among adults with hypertension, the proportion meeting the blood pressure goal of < 140/90 mm Hg increased from 36.8% (of 685 patients) preguideline to 50.3% (of 928 patients) postguideline (chi-square = 29.4, p < 0.001); the mean arterial pressure decreased from 102.7 mm Hg to 99.4 mm Hg (t = 5.45, p < 0.001). Cohort analysis of patients enrolled at both points in time confirmed these findings and showed an increase in the number of office visits from 5.4 to 6.7 visits per patient per year after guideline implementation (F = 10.9, p = 0.001). The use of a guideline-recommended medication for treatment of blood pressure was 35.9% preguideline and 36.2% postguideline. CONCLUSIONS: Implementation of a hypertension treatment guideline in primary care clinics was related to significantly improved hypertension control. Identification, tracking, and active outreach to patients with hypertension were used by all clinics.


Subject(s)
Hypertension/drug therapy , Outcome Assessment, Health Care , Practice Guidelines as Topic , Primary Health Care/standards , Adult , Aged , Blood Pressure , Cohort Studies , Cross-Sectional Studies , Disease Management , Female , Humans , Hypertension/diagnosis , Male , Middle Aged , Minnesota , Primary Health Care/methods
5.
J Fam Pract ; 47(4): 290-7, 1998 Oct.
Article in English | MEDLINE | ID: mdl-9789515

ABSTRACT

BACKGROUND: We investigated whether having a regular health care provider for diabetes was related to the intensity of care, use of preventive services, or glycemic control in a well-defined population of adults with diabetes. METHODS: Adults with diabetes who were continuously enrolled in a health maintenance organization (HMO) for 1 year were identified by diagnostic and pharmacy databases (estimated sensitivity = 0.91, positive predictive value = 0.94). In a stratified random sample, 1828 patients were sent a survey by mail that had a corrected response rate of 85.6%. Further data on utilization of services and glycosylated hemoglobin values were obtained from administrative databases and linked to survey responses. RESULTS: HMO members who reported having a regular health care provider (RP) for their diabetes (N = 1243) were comparable with those (N = 144) who denied having such a provider (NRP) in age, race, sex, comorbidity, and years of education, but had longer-duration diabetes (10.9 years vs 8.3 years; P = .002). After adjusting for age, sex, education level, duration of diabetes, and type of HMO clinic (owned vs contracted), RP subjects were more likely than NRPs (all P < .001) to follow a special diet for patients with diabetes (55% vs 33%), regularly monitor glucose levels at home (68% vs 47%), have greater frequency of glycosylated hemoglobin (Hb A1c) testing (65% vs 38%), have more foot examinations (42% vs 17%), have recommended cholesterol checks (77% vs 63%), and have had a recent preventive examination (86% vs 68%). Smaller differences favoring having a regular provider were noted for insulin use (48% vs 33%, odds ratio [OR] = 1.71, P = .013), for an influenza immunization within 1 year (65% vs 51%, P = .029), and for dilated retinal examinations (64% vs 51%, P < .027). No differences between groups were noted for dental checkups (69% vs 67%, P = .724) or likelihood of endocrinology referral (17% vs 10%, P = .104). Mean Hb A1c level was 8.2% (normal is < 6.1%) in the RP group and 8.6% in the NRP group (P = .182). Twelve percent of RPs and 24% of NRPs had an Hb A1c level of greater than 10% (chi 2 = 3.7, OR = 0.48, P = .05) after adjusting for age, sex, duration of diabetes, and education level. CONCLUSIONS: After adjustment for case mix, patients with diabetes who identified a regular primary health care provider for their diabetes were more likely to receive most recommended elements of diabetes care and to have better glycemic control than patients without such a provider. This effect was partially, but not completely, mediated by a higher number of clinic visits for those with a regular health care provider. Innovators seeking to improve diabetes care should be mindful of the relationship between having a regular primary health care provider and the quality of diabetes care.


Subject(s)
Continuity of Patient Care , Diabetes Mellitus/blood , Diabetes Mellitus/therapy , Family Practice , Glycated Hemoglobin/analysis , Adult , Diabetes Complications , Female , Health Maintenance Organizations , Humans , Male , Middle Aged , Minnesota , Office Visits/statistics & numerical data , Preventive Health Services/statistics & numerical data
6.
Am J Manag Care ; 4(3): 335-42, 1998 Mar.
Article in English | MEDLINE | ID: mdl-10178496

ABSTRACT

We conducted a study of the sensitivity, specificity, positive predictive value, and cost of two methods of identifying diagnosed diabetes mellitus or heart disease among members of a health maintenance organization (HMO). Among 3186 adult HMO members who were attending one primary care clinic, 2326 were reached for a telephone survey (efficiency = 0.73). Among these members, 1991 answered standardized questions to ascertain whether they had diabetes or heart disease (corrected response rate = 0.85). Linkage was then made to computerized diagnostic databases. By means of both a database method and a survey method, the 1976 members with complete data for analysis were classified as having or not having diabetes or heart disease. When results with the two methods disagreed, charts were reviewed to confirm the presence or absence of diabetes or heart disease. Diabetes was identified among 4.7% of adult members, and heart disease was identified among 3.7%. Identification of diabetes differed between the database method and the survey method (sensitivity 0.91 vs 0.98, specificity 0.99 vs 0.99, positive predictive value 0.94 vs 0.83). Identification of heart attach history was similar for the database method and the survey method (sensitivity 0.89 vs 0.95, specificity 0.99 vs 0.99, positive predictive value 0.79 vs 0.81). The cost of obtaining data was $13.50 per member for the survey method and $0.30 per member for the database method. Database methods or survey methods of identifying selected chronic diseases among HMO members may be acceptable for various purposes, but database identification methods appear to be less expensive and provide information on a higher proportion of HMO members than do survey methods. Accurate identification of chronic diseases among patients supports clinic-level measures for clinical improvement, research, and accountability.


Subject(s)
Database Management Systems , Diabetes Mellitus/epidemiology , Health Maintenance Organizations/statistics & numerical data , Health Status Indicators , Heart Diseases/epidemiology , Adult , Costs and Cost Analysis , Data Collection/economics , Diabetes Mellitus/diagnosis , Heart Diseases/diagnosis , Humans , Midwestern United States/epidemiology , Predictive Value of Tests , Risk Factors , Sensitivity and Specificity
7.
Eff Clin Pract ; 1(1): 26-32, 1998.
Article in English | MEDLINE | ID: mdl-10345257

ABSTRACT

OBJECTIVE: Aspirin use seems to reduce coronary artery disease events in some groups of patients. Factors associated with use of aspirin to prevent heart disease in an HMO population were examined. DESIGN: A population-based survey. SETTING: A large HMO in the midwestern United States. PARTICIPANTS: 8000 health plan members 40 years of age and older. MAIN OUTCOME MEASURES: The survey assessed use of aspirin, professional advice to use aspirin, and coronary heart disease risk factors and status. The sample was stratified by whether members had none, one, or more than one of the following chronic conditions: diabetes, hypertension, lipid disorder, or heart disease. The mailed survey had a corrected response rate of 82.4%. RESULTS: Overall, 38% of respondents reported using aspirin at least three times a week to prevent heart disease. Aspirin use did not vary in owned versus contracted clinics. Aspirin use was 71.3% in patients with and 27.7% in patients without diagnosed coronary heart disease (P < 0.001). In logistic regression models, professional advice to take aspirin was strongly associated with self-reported use of aspirin (odds ratio, 13.86) (P < 0.001) after adjustment for age, sex, level of education, and chronic disease status. CONCLUSIONS: Aspirin is widely used by HMO members with coronary artery disease to prevent subsequent coronary artery disease events. Professional advice to use aspirin seems to be strongly related to aspirin use.


Subject(s)
Aspirin/therapeutic use , Health Maintenance Organizations/statistics & numerical data , Heart Diseases/prevention & control , Patient Compliance , Adult , Aged , Aspirin/economics , Diabetes Complications , Drug Costs , Female , Health Care Surveys , Heart Diseases/complications , Humans , Hyperlipidemias/complications , Hypertension/complications , Male , Middle Aged , Midwestern United States , Surveys and Questionnaires
8.
Diabetes Care ; 20(12): 1847-53, 1997 Dec.
Article in English | MEDLINE | ID: mdl-9405905

ABSTRACT

OBJECTIVE: We tested the hypothesis that level of glycemic control is related to medical care costs in adults with diabetes. RESEARCH DESIGN AND METHODS: Regression analysis was used to estimate the relationship between glycemic control and medical care charges for 3,017 adults with diabetes who were continuously enrolled in a large health maintenance organization (HMO) over a 4-year period. Diagnosis of diabetes was ascertained from diagnostic and pharmaceutical databases using a method with an estimated sensitivity of 0.91 and an estimated specificity of 0.99. Charges for care included defined outpatient and inpatient services. Patients who disenrolled or who died during the 4-year period were excluded from the main analysis. RESULTS: Charges for medical care for patients with diabetes from 1993 to 1995 were closely related to HbA1c level in 1992 before and after adjustment for age, sex, coronary heart disease, and hypertension. Standardized 3-year estimates of charges ranged from $10,439 for patients without comorbid conditions to $44,417 for those with heart disease and hypertension. Medical care charges increased significantly for every 1% increase above HbA1c of 7%. For a person with an HbA1c value of 6%, successive 1% increases in HbA1c resulted in cumulative increases in charges of approximately 4, 10, 20, and 30%. The increase in charges accelerated as the HbA1c value increased. For patients with diabetes only, or with diabetes plus other chronic conditions, the rate of increase in charges with HbA1c was consistent. CONCLUSIONS: HbA1c provides useful information to providers and patients regarding both health status and future medical care charges. Economic data suggest that clinicians should assign high importance to low HbA1c results and aggressively maintain the HbA1c status of patients who have low HbA1c values. For economic as well as clinical reasons, it may be beneficial to lower HbA1c when it is > 8% and to reduce cardiovascular risk factors. The medical charge data suggest that investment in clinical systems to improve diabetes care may benefit both payers and patients.


Subject(s)
Diabetes Mellitus/economics , Glycated Hemoglobin/economics , Health Care Costs/statistics & numerical data , Health Maintenance Organizations/economics , Adult , Aged , Cohort Studies , Diabetes Complications , Female , Glycated Hemoglobin/analysis , Glycated Hemoglobin/metabolism , Heart Diseases/economics , Humans , Hypertension/economics , Male , Middle Aged , Minnesota , Organizations, Nonprofit/economics , Regression Analysis
9.
J Ambul Care Manage ; 20(4): 17-23, 1997 Oct.
Article in English | MEDLINE | ID: mdl-10181619

ABSTRACT

The investigators constructed an index measure of cardiovascular risk and scored 1.991 adults as having high, average, or low cardiovascular risk. High cardiovascular risk was positively associated with hospital admissions (odds ratio [OR] = 3.9, p < 0.0001), total hospital days (OR = 4.0, p < 0.001), primary care clinic visits (OR = 7.3, p < 0.0001), and subspecialty clinic visits (OR = 2.3, p = 0.0003), compared to low cardiovascular risk, after controlling in multivariate analyses for gender and age. The index can provide estimates of utilization, costs, and potential preventability of adverse cardiovascular events, can be used to identify groups of patients in need of various systematic interventions, and can provide population-based ways to evaluate the results of interventions.


Subject(s)
Cardiovascular Diseases/epidemiology , Database Management Systems , Managed Care Programs/statistics & numerical data , Risk Assessment , Adult , Community Health Planning , Data Collection , Humans , Multivariate Analysis , Outcome Assessment, Health Care , United States/epidemiology
10.
J Fam Pract ; 44(5): 462-7, 1997 May.
Article in English | MEDLINE | ID: mdl-9152263

ABSTRACT

BACKGROUND: We conducted an historical cohort study to evaluate the relative effectiveness of niacin and lovastatin in the treatment of dyslipidemias in patients enrolled in a health maintenance organization (HMO). METHODS: To be eligible for this study, adults aged 18 years and older who were initially treated with either niacin or lovastatin between January 1, 1992, and December 31, 1993, were identified from pharmacy databases. Each potentially eligible member with a fasting lipid panel prior to initiation of drug therapy and with a second fasting lipid panel between 9 and 15 months after initiation of drug therapy was included in the study. A total of 244 patients treated with niacin and 160 patients treated with lovastatin had complete data and are subjects of this report. RESULTS: Patients initially treated with lovastatin had higher baseline mean cholesterol and low-density lipoprotein (LDL) levels as well as higher rates of diabetes mellitus and heart disease than did patients initially treated with niacin. Lovastatin use was associated with a mean 25.8% decrease in LDL cholesterol, while niacin use was associated with a mean 17.5% drop in LDL cholesterol (t = 3.19, P < .002). Niacin use was associated with a 16.3% improvement in high-density lipoprotein (HDL) cholesterol, while HDL-cholesterol levels in the lovastatin group improved 1.5% (t = 4.74, P < .001). Niacin use was associated with an 18.4% improvement in triglycerides, while lovastatin use was associated with an 8% improvement in triglyceride levels (t = 2.81, P = .005). Differences in LDL/HDL ratio from before treatment to follow-up were no different in the two groups of patients (t = -1.21, P = .22). A total of 46% of patients initially treated with either drug reached their treatment goals in accordance with those set by the National Cholesterol Education Program. Drug discontinuation rates were 73% for niacin and 52% for lovastatin at follow-up, which averaged 10.7 months in each group. CONCLUSIONS: These results suggest that both niacin and lovastatin are effective in treating dyslipidemic patients in this care system, and that physicians appropriately use lovastatin more often for patients with higher baseline LDL levels and more comorbidity. The data also strongly suggest that establishing an organized, population-based approach to systematically identify, treat, and monitor patients with dyslipidemias may be the single most important intervention HMOs should consider for improving control of dyslipidemias on a population basis.


Subject(s)
Health Maintenance Organizations , Hyperlipidemias/drug therapy , Hypolipidemic Agents/therapeutic use , Lovastatin/therapeutic use , Niacin/therapeutic use , Cholesterol, HDL/blood , Cholesterol, LDL/blood , Cohort Studies , Female , Follow-Up Studies , Humans , Hyperlipidemias/blood , Male , Middle Aged , Midwestern United States , Patient Compliance , Triglycerides/blood
11.
Arch Fam Med ; 5(9): 502-6, 1996 Oct.
Article in English | MEDLINE | ID: mdl-8930220

ABSTRACT

OBJECTIVE: To evaluate the impact of a continuous quality improvement (CQI) intervention on glycemic control of patients with diabetes mellitus attending a primary care clinic. METHODS: A CQI process designed by the Minnesota Department of Health to improve diabetes care was implemented at a volunteer clinic, with another similar clinic not using the CQI process assessed for comparison. Adults with diabetes were identified at both clinics using diagnostic and pharmacy databases. Glycosylated hemoglobin (HbA1c) values (reference range, 4.3%-6.1%) and out-patient utilization and charges were compared for all patients with diabetes at each clinic for the 12 months before and 18 months after initiation of the CQI intervention. RESULTS: The mean HbA1c value at the intervention clinic fell from 8.9% at baseline to 8.4% at 12 months and to 7.9% at 18 months. The mean HbA1c value at the comparison clinic was 8.9% at baseline, 8.9% at 12 months, and 8.8% at 18 months (difference between clinics, t = 4.13, P < .001). Differences after the intervention in the proportion of patients at the comparison clinic (n = 121) vs the intervention clinic (n = 122) with HbA1c values of 8% or less (40% vs 51%), between 8% and 10% (33% vs 37%), and 10% or greater (27% vs 12%) were unlikely due to chance (chi 2 = 9.7, 2 df, P = .008). The intervention was not associated with increased utilization of outpatient visits or outpatient charges. CONCLUSIONS: Involvement of nurses, physicians, and managers in a CQI process can improve patients' glycemic control in some health maintenance organization primary care settings, without increasing utilization or charges. Health maintenance organizations should consider CQI as one possible method to improve diabetes outcomes.


Subject(s)
Blood Glucose , Diabetes Mellitus/blood , Health Maintenance Organizations/standards , Total Quality Management , Adult , Ambulatory Care/standards , Glycated Hemoglobin/metabolism , Humans , Middle Aged , Patient Care Team , Primary Health Care/standards
13.
Am J Trop Med Hyg ; 30(3): 699-705, 1981 May.
Article in English | MEDLINE | ID: mdl-6266266

ABSTRACT

Experiments were conducted to determine whether transovarial transmission (TOT) of St. Louis encephalitis (SLE) virus occurs in Culex pipiens complex mosquitoes, the principal vectors of SLE virus in the central-eastern United States. In 1978, field-collected mosquitoes from Memphis, Tennessee, and McLeansboro, Illinois, were used; during 1979, colonized mosquitoes from Chicago, Illinois, and Memphis, Tennessee, were used. Mosquitoes were infected by feeding on viremic chicks inoculated with an SLE virus strain isolated from Cx. pipiens complex mosquitoes collected from Memphis, Tennessee, in 1976. During the 1979 experiments, progeny larval and adult mosquitoes were held at two temperatures, 18 and 25 degrees C. Progeny were tested for virus by plaque assay in duck embryo cell cultures and by inoculation of Aedes albopictus C6/36 cells and examination by immunofluorescence. In 1978, most of the progeny tested were from the first ovarian cycle, and a single occurrence of TOT was documented. In 1979, a single TOT occurred from 46,856 first ovarian cycle progeny, whereas 7 of 9,234 progeny of the second ovarian cycle were infected. The rate of TOT was higher for progeny of Memphis than Chicago mosquitoes, and for mosquitoes held at 18 degrees C than at 25 degrees C; however, these differences were not statistically significant. Four positive pools were females, and three were fed on chicks for transmission attempts. The positive Chicago mosquito pool failed to transmit, but both Memphis pools successfully transmitted virus. The overall rates of TOT of SLE virus in progeny of the first and second ovarian cycle were, respectively, 1/45, 151 and 1/1,460. The significance of these results as they relate to the natural history of SLE virus is discussed.


Subject(s)
Culex/microbiology , Encephalitis Virus, St. Louis/growth & development , Flavivirus/growth & development , Animals , Chickens/microbiology , Encephalitis, St. Louis/transmission , Fluorescent Antibody Technique
14.
Am J Trop Med Hyg ; 29(5): 969-83, 1980 Sep.
Article in English | MEDLINE | ID: mdl-7435797

ABSTRACT

A second virus with distinct biological, serological, and physiochemical properties was detected as a minority viral subpopulation in specimens of Cliff Swallow nest bugs (Oeciacus vicarius) and nestling bird sera containing Fort Morgan (FM) virus. The second virus, detected by a breakthrough neutralization test employing FM antiserum, was present in 5 of 11 FM virus-positive pools of nest bugs and in 4 of 38 birds from Colorado and South Dakota. The concentration of the second virus was 10-fold to 1,000-fold lower than that of FM virus. The second virus, which was provisionally named "Bijou Bridge" (BB) virus was shown by conventional serological tests to be a member of the Venezuelan equine encephalomyelitis (VEE) complex, and by tests employing antisera to the E2 viral glycoprotein to be identical with Tonate virus, previously isolated from birds and mosquitoes only in French Guiana. Experimental infection of House Sparrows and Cliff Swallows showed that they develop brief BB viremias and antibodies. Oe. vicarius bugs were resistant to oral infection with BB virus. The epidemiological significance of recovery of Tonate virus in North American is discussed.


Subject(s)
Birds/microbiology , Encephalomyelitis, Equine/transmission , Encephalomyelitis, Venezuelan Equine/transmission , Hemiptera/microbiology , Animals , Encephalitis Virus, Western Equine/isolation & purification , Seasons , Serotyping , Species Specificity
16.
Infect Immun ; 10(3): 553-64, 1974 Sep.
Article in English | MEDLINE | ID: mdl-4426699

ABSTRACT

Six species of rodents from Kern County, California, were inoculated subcutaneously with western equine encephalomyelitis (WEE) virus to determine their susceptibility to infection and their potential as natural hosts. Ammospermophilus nelsoni, Citellus beecheyi, Dipodomys heermanni, Dipodomys nitratoides, Peromyscus maniculatus, and Sciurus griseus were readily infected. Infection was usually fatal in Dipodomys species, C. beecheyi, and S. griseus, but was clinically inapparent in other species. Viremic responses varied greatly in magnitude and duration in different species and with different viral strains. Viremic animals that survived developed high titers of hemagglutination-inhibiting antibody. Hemagglutination-inhibiting and neutralizing antibodies persisted at high titers for at least 8 to 58 weeks after infection, except in P. maniculatus. If animals died during or shortly after the viremic phase of infection, the virus usually was recoverable from numerous organs. Long-term survival of virus could not be demonstrated in A. nelsoni and Dipodomys species. It is concluded that A. nelsoni and P. maniculatus are not important natural hosts of WEE virus; they are susceptible to infection and develop antibodies, but serological surveys of the same species rarely reveal evidence of infection. S. griseus, D. heermanni, D. nitratoides, and possibly C. beecheyi are aberrant hosts of WEE virus since most of them died when infected. Two species of ticks that are ectoparasitic on rodents in Kern County were evaluated as vectors of WEE virus. Dermacentor parumapertus failed to become infected after feeding on viremic hosts, and Ornithodorus parkeri became infected but failed to transmit virus.


Subject(s)
Encephalitis Virus, Western Equine/immunology , Encephalomyelitis, Equine/immunology , Rodentia/immunology , Animals , Antibodies, Viral/analysis , Antibody Formation , Brain/microbiology , California , Chickens , Disease Vectors , Encephalomyelitis, Equine/transmission , Neutralization Tests , Ticks
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