Showing papers by "Centers for Disease Control and Prevention published in 1996"

Molecular Cloning and Disease Association of Hepatitis G Virus: A Transfusion-Transmissible Agent

Abstract: An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

Heat-Related Deaths during the July 1995 Heat Wave in Chicago

Abstract: Background During a record-setting heat wave in Chicago in July 1995, there were at least 700 excess deaths, most of which were classified as heat-related We sought to determine who was at greatest risk for heat-related death Methods We conducted a case–control study in Chicago to identify risk factors associated with heat-related death and death from cardiovascular causes from July 14 through July 17, 1995 Beginning on July 21, we interviewed 339 relatives, neighbors, or friends of those who died and 339 controls matched to the case subjects according to neighborhood and age Results The risk of heat-related death was increased for people with known medical problems who were confined to bed (odds ratio as compared with those who were not confined to bed, 55) or who were unable to care for themselves (odds ratio, 41) Also at increased risk were those who did not leave home each day (odds ratio, 67), who lived alone (odds ratio, 23), or who lived on the top floor of a building (odds ratio, 47) Ha

Exposure of the US Population to Environmental Tobacco Smoke: The Third National Health and Nutrition Examination Survey, 1988 to 1991

Abstract: Objective. —To estimate the extent of exposure of the US population to environmental tobacco smoke and the contribution of the home and workplace environment to environmental tobacco smoke exposure. Design. —Nationally representative cross-sectional survey including questionnaire information from persons aged 2 months and older (n=16 818) and measurements of serum cotinine (a metabolite of nicotine) from persons aged 4 years and older (n=10 642). Setting/Participants. —Participants in the Third National Health and Nutrition Examination Survey, October 25, 1988, to October 21, 1991. Results. —Of US children aged 2 months to 11 years, 43% lived in a home with at least 1 smoker, and 37% of adult non—tobacco users lived in a home with at least 1 smoker or reported environmental tobacco smoke exposure at work. Serum cotinine levels indicated more widespread exposure to nicotine. Of non—tobacco users, 87.9% had detectable levels of serum cotinine. Both the number of smokers in the household and the hours exposed at work were significantly and independently associated ( P Conclusions. —The high proportion of the population with detectable serum cotinine levels indicates widespread exposure to environmental tobacco smoke in the US population. Both the home and workplace environments significantly contribute to environmental tobacco smoke exposure in the United States. ( JAMA . 1996;275:1233-1240)

Invasive group A streptococcal infections in Ontario, Canada

Abstract: Background Several reports suggest that the incidence of invasive group A streptococcal infections, including streptococcal toxic shock syndrome and necrotizing fasciitis, is increasing. Methods During 1992 and 1993 we conducted prospective, population-based surveillance of invasive group A streptococcal disease in Ontario, Canada. We reviewed clinical and laboratory records, searched for secondary cases of invasive disease, and cultured specimens from household contacts. Results We identified 323 patients with invasive group A streptococcal infections, for an annual incidence of 1.5 cases per 100,000 population. The rates were highest in young children and the elderly. Fifty-six percent of the patients had underlying chronic illness. Risk factors for disease included infection with the human immunodeficiency virus, cancer, diabetes, alcohol abuse, and chickenpox. The most common clinical presentations were soft-tissue infection (48 percent), bacteremia with no septic focus (14 percent), and pneumonia (11...

Association of Elevated Serum Lipid Levels With Retinal Hard Exudate in Diabetic Retinopathy: Early Treatment Diabetic Retinopathy Study (ETDRS) Report 22

Abstract: Objective: To evaluate the relationship between serum lipid levels, retinal hard exudate, and visual acuity in patients with diabetic retinopathy. Design: Observational data from the Early Treatment Diabetic Retinopathy Study. Participants: Of the 3711 patients enrolled in the Early Treatment Diabetic Retinopathy Study, the first 2709 enrolled had serum lipid levels measured. Main Outcome Measures: Baseline fasting serum lipid levels, best-corrected visual acuity, and assessment of retinal thickening and hard exudate from stereoscopic macular photographs. Results: Patients with elevated total serum cholesterol levels or serum low-density lipoprotein cholesterol levels at baseline were twice as likely to have retinal hard exudates as patients with normal levels. These patients were also at higher risk of developing hard exudate during the course of the study. The risk of losing visual acuity was associated with the extent of hard exudate even after adjusting for the extent of macular edema. Conclusions: These data demonstrate that elevated serum lipid levels are associated with an increased risk of retinal hard exudate in persons with diabetic retinopathy. Although retinal hard exudate usually accompanies diabetic macular edema, increasing amounts of exudate appear to be independently associated with an increased risk of visual impairment. Lowering elevated serum lipid levels has been shown to decrease the risk of cardiovascular morbidity. The observational data from the Early Treatment Diabetic Retinopathy Study suggest that lipid lowering may also decrease the risk of hard exudate formation and associated vision loss in patients with diabetic retinopathy. Preservation of vision may be an additional motivating factor for lowering serum lipid levels in persons with diabetic retinopathy and elevated serum lipid levels.

Sequencing emm-specific PCR products for routine and accurate typing of group A streptococci

Abstract: Rapid sequence analysis of specific PCR products was used to accurately deduce emm types corresponding to the majority of the known group A streptococcal (GAS) M serotypes. The study involved 95 M type reference GAS strains and a survey of 74 recent clinical isolates. A high percentage of agreement between M type serology and the previously published 5' sequences of the emm genes of M type reference strains was noted. The 5' sequences for six established M protein genes--the emm-32, emm-34, emm-38, emm-40, emm-42, and emm-71 genes--were determined to supplement the existing emm sequence database. Rapid sequence analysis differentiated serologically M-nontypeable strains and was used to establish the probable.

Seroconversion to antibodies against Kaposi's sarcoma-associated herpesvirus-related latent nuclear antigens before the development of Kaposi's sarcoma

Abstract: Background If Kaposi's sarcoma–associated herpesvirus (KSHV) is the cause of Kaposi's sarcoma, serologic evidence of infection should be present in patients before the disease develops. Methods Using an immunoblot assay for two latent nuclear antigens of KSHV, we tested serum samples from homosexual male patients with the acquired immunodeficiency syndrome (AIDS) with and without Kaposi's sarcoma, HIV-infected men with hemophilia, HIV-seronegative blood donors, and HIV-seronegative patients with high titers of antibodies against Epstein–Barr virus (EBV). Serial serum samples obtained from patients with Kaposi's sarcoma before the diagnosis of the disease were tested for evidence of seroconversion. Results Of 40 patients with Kaposi's sarcoma, 32 (80 percent) were positive for antibodies against KSHV antigens by the immunoblot assay, as compared with only 7 of 40 homosexual men (18 percent) without Kaposi's sarcoma immediately before the onset of AIDS. Of 122 blood donors, 22 EBV-infected patients, and 20 ...

Incidence of mild and moderate brain injury in the United States, 1991.

Abstract: The 1991 National Health Interview Survey was analysed to describe the incidence of mild and moderate brain injury in the United States. Data were collected from 46761 households and weighted to re...

The estimated prevalence and incidence of HIV in 96 large US metropolitan areas

Abstract: OBJECTIVES: This study sought to estimate the size and direction of the human immunodeficiency virus (HIV) epidemic in US metropolitan statistical areas (MSAs) with populations greater than 500,000. METHODS: A "components model" from review of more than 350 documents, several large datasets, and information from 220 public health personnel was used. Data review focused on injection drug users, men who have sex with men, and high-risk heterosexual men and women. RESULTS: In the 96 MSAs, there are, broadly, an estimated 1.5 million injection drug users, 1.7 million gay and bisexual men, and 2.1 million at-risk heterosexuals, and, among them, an estimated 565,000 prevalent and 38,000 incident HIV infections. This implies about 700,000 prevalent and 41,000 new HIV infections yearly in the United States. Roughly half of all estimated new infections are occurring among injection drug users, most of them in northeastern cities, Miami, and San Juan. Gay and bisexual men still represent most prevalent HIV infectio...

Selected aspects of the socioeconomic impact of nosocomial infections: morbidity, mortality, cost, and prevention.

Abstract: Approximately 2 million nosocomial infections occur annually in the United States. These infections result in substantial morbidity, mortality, and cost. The excess duration of hospitalization secondary to nosocomial infections has been estimated to be 1 to 4 days for urinary tract infections, 7 to 8.2 days for surgical site infections, 7 to 21 days for bloodstream infections, and 6.8 to 30 days for pneumonia. The estimated mortalities associated with nosocomial bloodstream infections and pneumonia are 23.8% to 50% and 14.8% to 71% (overall), or 16.3% to 35% and 6.8% to 30% (attributable), respectively. The estimated average costs of these infections are $558 to $593 for each urinary tract infection, $2,734 for each surgical site infection, $3,061 to $40,000 for each bloodstream infection, and $4,947 for each pneumonia. Even minimally effective infection control programs are cost-effective. In countries with prospective payment systems based on diagnosis-related groups, hospitals lose from $583 to $4,886 for each nosocomial infection. As administrators focus on cost containment, increased support should be given to infection control programs so that preventable nosocomial infections and their associated expenditures can be averted.

In situ detection of tissue factor in vascular endothelial cells: Correlation with the malignant phenotype of human breast disease

Abstract: Expression of tissue factor (TF) in the endothelium has been observed only rarely in human disease and has been thought to be elaborated on the surface of vascular endothelial cells (VECs) in vitro as an artifact of tissue culture. Using monoclonal antibodies and a novel probe for functional TF, we have localized TF to the VECs (and tumor cells) within the tumors of seven patients with invasive breast cancer but not in the VECs (or tumor cells) of benign tumors from ten patients with fibrocystic disease of the breast. The potent procoagulant TF was shown to be a marker of the initiation of angiogenesis in human breast cancer. Further evidence that the TF was the demonstration of a similar distribution of cross–linked fibrin only in the VECs of the malignant tumors. We interpret these data as further support for the concept that tumor cells can activate nearby VECs and regulate blood vessel growth in vivo. Large clinicalpathologic studies will be necessary to determine whether TF is a useful marker for the “switch to the angiogenic phenotype” in human breast disease and/or correlates with the thromboembolic complications of breast cancer.

The virion glycoproteins of Ebola viruses are encoded in two reading frames and are expressed through transcriptional editing.

Abstract: In late 1994 and early 1995, Ebola (EBO) virus dramatically reemerged in Africa, causing human disease in the Ivory Coast and Zaire. Analysis of the entire glycoprotein genes of these viruses and those of other EBO virus subtypes has shown that the virion glycoprotein (130 kDa) is encoded in two reading frames, which are linked by transcriptional editing. This editing results in the addition of an extra nontemplated adenosine within a run of seven adenosines near the middle of the coding region. The primary gene product is a smaller (50-70 kDa), nonstructural, secreted glycoprotein, which is produced in large amounts and has an unknown function. Phylogenetic analysis indicates that EBO virus subtypes are genetically diverse and that the recent Ivory Coast isolate represents a new (fourth) subtype of EBO virus. In contrast, the EBO virus isolate from the 1995 outbreak in Kikwit, Zaire, is virtually identical to the virus that caused a similar epidemic in Yambuku, Zaire, almost 20 years earlier. This genetic stability may indicate that EBO viruses have coevolved with their natural reservoirs and do not change appreciably in the wild.

Leisure-time physical activity among US adults. Results from the Third National Health and Nutrition Examination Survey.

Abstract: Background: The prevalence of no leisure-time physical activity (LTPA) among US adults is estimated to be between 24% and 30%. Such information, however, usually does not include prevalence estimates for non-Hispanic blacks, Mexican Americans, and the elderly. Objective: To assess the prevalence of participation in leisure-time physical activity among US adults. Methods: Between 1988 and 1991, 9488 adults aged 20 years and older were interviewed in their home as part of the third National Health and Nutrition Examination Survey. A clinic examination in a mobile center was also included. Mexican Americans, non-Hispanic blacks, and the elderly were oversampled to produce reliable estimates for these groups. Questions were asked about the type and frequency of physically active hobbies, sports, and exercises. Results: The prevalence of no LTPA for US adults aged 20 years or older from 1988 through 1991 was 22%. The rate was higher in women (27%) than in men (17%). Mexican-American men (33%) and women (46%) and non-Hispanic black women (40%) had the highest rates of no LTPA. Participation in moderate to vigorous LTPA five or more times per week decreased with age, with the largest decreases observed among non-Hispanic black men and women. In almost all subpopulations, gardening and/or yard work and walking were stated as the two top LTPAs of choice. Conclusions: Many Americans are inactive or irregularly active during their leisure time. Rates of inactivity are greater for women, older persons, non-Hispanic blacks, and Mexican Americans. Intervention strategies meant to promote lifetime physical activities among all Americans represents a major health priority. (Arch Intern Med. 1996;156:93-98)

The relationship between body weight and mortality : a quantitative analysis of combined information from existing studies

Abstract: OBJECTIVE : To estimate the relationship between body mass index (BMI, kg/m 2 ) and all-cause mortality with information from the published scientific literature. DESIGN : Meta-analysis using a hierarchical, mixed model. The analysis included random effects for information sources and fixed effects for factors that may modify the BMI-mortality relationship such as smoking, control for disease, and country of origin, which allowed combining information from diverse studies. MAIN OUTCOME MEASURES : Predicted probability of death over a given duration of follow-up plotted by BMI for sex-age cohorts of white race. RESULTS : An extensive search identified nineteen prospective cohort studies that met inclusion criteria. A U-shaped relationship between BMI and mortality was demonstrated for 50-year-old men followed for 30 years. Mortality risk increased with low and high BMI ( 28) in groups of non-smokers without evidence of disease upon study entry. Limited information from studies of women indicated that, with 10 year follow-up, there was little relationship between BMI and mortality for (1) non-smokers and for (2) mixtures of smokers and non-smokers. CONCLUSION : This quantitative analysis of existing studies revealed increased mortality at moderately low BMI for white men comparable to that observed at extreme overweight, which does not appear to be due to smoking or existing disease. Attention to the health risks of underweight is needed, and body weight recommendations for optimum longevity need to be considered in light of these risks.

Trends in infectious diseases mortality in the United States.

Abstract: Objective. —To evaluate recent trends in infectious diseases mortality in the United States. Design. —Descriptive study of infectious disease mortality, classifyingInternational Classification of Diseases, Ninth Revisioncodes as infectious diseases, consequence of infectious diseases, or not infectious diseases. Multiple cause-of-death tapes from the National Center for Health Statistics for the years 1980 through 1992 were used, with a focus on underlying cause-of-death data and on codes that exclusively represent infectious diseases. Setting. —United States. Subjects. —All persons who died between 1980 and 1992. Main Outcome Measure. —Death. Results. — Between 1980 and 1992, the death rate due to infectious diseases as the underlying cause of death increased 58%, from 41 to 65 deaths per 100 000 population in the United States. Age-adjusted mortality from infectious diseases increased 39% during the same period. Infectious diseases mortality increased 25% among those aged 65 years and older (from 271 to 338 per 100 000), and 6.3 times among 25- to 44-year-olds (from six to 38 deaths per 100000). Mortality due to respiratory tract infections increased 20%, from 25 to 30 deaths per 100 000, deaths attributed to human immunodeficiency virus increased from virtually none to 13 per 100000 in 1992, and the rate of death due to septicemia increased 83% from 4.2 to 7.7 per 100000. Conclusions. —Despite historical predictions that infectious diseases would wane in the United States, these data show that infectious diseases mortality in the United States has been increasing in recent years. (JAMA. 1996;275:189-193)

Nosocomial Infections Among Neonates in High-risk Nurseries in the United States

Abstract: Background. Nosocomial infections result in considerable morbidity and mortality among neonates in high-risk nurseries (HRNs). Purpose. To examine the epidemiology of nosocomial infections among neonates in level III HRNs. Methods. Data were collected from 99 hospitals with HRNs participating in the National Nosocomial Infections Surveillance system, which uses standard surveillance protocols and nosocomial infection site definitions. The data included information on maternal acquisition of and risk factors for infection, such as device exposure, birth weight category (≤1000, 1001 through 1500, 1501 through 2500, and >2500 g), mortality, and the relationship of the nosocomial infection to death. Results. From October 1986 through September 1994, these hospitals submitted data on 13 179 nosocomial infections. The bloodstream was the most frequent site of nosocomial infection in all birth weight groups. Nosocomial pneumonia was the second most common infection site, followed by the gastrointestinal and eye, ear, nose, and throat sites. The most common nosocomial pathogens among all neonates were coagulase-negative staphylococci, Staphylococcus aureus, enterococci, Enterobacter sp, and Escherichia coli. Group B streptococci were associated with 46% of bloodstream infections that were maternally acquired; coagulase-negative staphylococci were associated with 58% of bloodstream infections that were not maternally acquired, most of which (88%) were associated with umbilical or central intravenous catheters. Conclusions. Bloodstream infections, the most frequent nosocomial infections in all birth weight groups, should be a major focus of surveillance and prevention efforts in HRNs. For bloodstream infections, stratification of surveillance data by maternal acquisition will help focus prevention efforts for group B streptococci outside the HRN. Within the nursery, bloodstream infection surveillance should focus on umbilical or central intravenous catheter use, a major risk factor for infection.

Nontraditional Epidemiologic Approaches in the Analysis of Gene Environment Interaction: Case-Control Studies with No Controls!

Abstract: Although case-control studies are suitable for assessing gene-environment interactions, choosing appropriate control subjects is a valid concern in these studies. The authors review three nontraditional study designs that do not include a control group : 1) the case-only study, 2) the case-parental control study, and 3) the affected relative-pair method. In case-only studies, one can examine the association between an exposure and a genotype among case subjects only. Odds ratios are interpreted as a synergy index on a multiplicative scale, with independence assumed between the exposure and the genotype. In case-parental control studies, one can compare the genotypic distribution of case subjects with the expected distribution based on parental genotypes when there is no association between genotype and disease ; the effect of a genotype can be stratified according to case subjects' exposure status. In affected relative-pair studies, the distribution of alleles identical by descent between pairs of affected relatives is compared with the expected distribution based on the absence of genetic linkage between the locus and the disease ; the analysis can be stratified according to exposure status. Some or all of these methods have certain limitations, including linkage disequilibrium, confounding, assumptions of Mendelian transmission, an inability to measure exposure effects directly, and the use of a multiplicative scale to test for interaction. Nevertheless, they provide important tools to assess gene-environment interaction in disease etiology.

The role of understaffing in central venous catheter-associated bloodstream infections

Abstract: Objective:To determine risk factors for central venous catheter-associated bloodstream infections (CVC-BSI) during a protracted outbreak.Design:Case-control and cohort studies of surgical intensive care unit (SICU) patients.Setting:A university-affiliated Veterans Affairs medical center.Patients:Case-control study: all patients who developed a CVC-BSI during the outbreak period (January 1992 through September 1993) and randomly selected controls. Cohort study: all SICU patients during the study period (January 1991 through September 1993).Measurements:CVC-BSI or site infection rates, SICU patient clinical data, and average monthly SICU patient-to-nurse ratio.Results:When analyzed by hospital location and site, only CVC-BSI in the SICU had increased significantly in the outbreak period compared to the previous year (January 1991 through December 1991: pre-outbreak period). In SICU patients, CVC-BSI were associated with receipt of total parenteral nutrition [TPN]; odds ratio, 16; 95% confidence inter val, 4 to 73). When we controlled for TPN use, CVC-BSI were associated with increasing severity of illness and days on assisted ventilation. SICU patients in the out-break period had shorter SICU and hospital stays, were younger, and had similar mortality rates, but received more TPN compared with patients in the pre-outbreak period. Furthermore, the patient-to-nurse ratio significantly increased in the outbreak compared with the pre-outbreak period. When we controlled for TPN use, assisted ventilation, and the period of hospitalization, the patient-to-nurse ratio was an independent risk factor for CVC-BSI in SICU patients.Conclusions:Nursing staff reductions below a critical level, during a period of increased TPN use, may have contributed to the increase in CVC-BSI in the SICU by making adequate catheter care difficult. During healthcare reforms and hospital downsizing, the effect of staffing reductions on patient outcome (ie, nosocomial infection) needs to be critically assessed.

The effect of socioeconomic status on chronic disease risk behaviors among US adolescents

Abstract: Objective. —To examine the relationship between socioeconomic status and risk behaviors for chronic disease among a nationally representative sample of adolescents in the United States. Design. —Household survey, the Youth Risk Behavior Survey supplement to the 1992 National Health Interview Survey. Setting. —United States. Participants. —Nationally representative sample of 6321 adolescents aged 12 to 17 years. Main Outcome Measures. —Standardized prevalence rates and logistic and multiple regression models were used to examine the effect of educational level of the responsible adult and family income on 5 risk behaviors for chronic disease among adolescents—cigarette smoking, sedentary lifestyle, insufficient consumption of fruits and vegetables, excessive consumption of foods high in fat, and episodic heavy drinking of alcohol. Results. —Most adolescents (63%) reported 2 or more of the 5 risk behaviors. Controlling for age, sex, race/ethnicity, and school enrollment status of adolescents, as the educational level of the responsible adult increased, cigarette smoking, sedentary lifestyle, and insufficient consumption of fruits and vegetables were less likely among adolescents. Among girls, but not boys, consumption of foods high in fat decreased as education of the responsible adult increased. As family income increased, adolescents were less likely to smoke cigarettes, less likely to be sedentary, and less likely to engage in episodic heavy drinking. Conclusion. —Among adolescents, risk behaviors for chronic disease are common and inversely related to socioeconomic status. Improved community- and school-based programs to prevent such behaviors among adolescents are needed, especially among socially and economically disadvantaged youth.

Review Of G And P Typing Results From A Global Collection Of Rotavirus Strains: Implications For Vaccine Development

Abstract: Candidate rotavirus vaccines have been prepared with reassortant strains specifically to protect against the 4 major rotavirus G serotypes (G1 -4). Many studies using P (VP4) genotyping methods have indicated that, worldwide, rotavirus strains of the 4 common G serotypes are each associated with 1 P genotype: GI, G3, and G4 are associated with P[8], and G2 is associated with P[4]. In contrast, G and P genotyping of rotavirus in specimens from India revealed that a high percentage of the childhood diarrhea strains belong to genotype P[6], and the most common strain had an unusual G serotype, G9. Similarly, in all regions surveyed in Brazil, apparent reassortants of genotype P[8], G5 were found in children with gastroenteritis. These studies indicate that while rotavirus strains have limited diversity in many settings, reassortment between common and uncommon serotypes or animal strains can arise in some settings and, thus, lead to unusual diversity.

Respiratory Syncytial Virus Is an Important Cause of Community-Acquired Lower Respiratory Infection among Hospitalized Adults

Abstract: Respiratory syncytial virus (RSV), the most important cause of lower respiratory disease in infants and young children, is rarely considered among the causes for community-acquired lower respiratory infection in adults. All noninstitutionalized adults hospitalized with community-acquired pneumonia in two Ohio counties were evaluated between December 1990 and May 1992. Fifty-three (4.4%) of 1195 adults admitted during the RSV seasons and 4 (1.0%) of 390 in the off-season had serologic evidence of RSV infection, making RSV one of the four most common pathogens identified. RSV-infected patients had clinical features (e.g., wheezing and rhonchi) that distinguished them from all non-RSV-infected patients and other features (e.g., nonelevated white blood cell counts) that distinguished them from those infected with bacterial or atypical agents. However, RSV infection was not diagnosed during hospitalization for any of the 57 RSV-infected patients. RSV should be considered in the differential diagnosis for adults hospitalized between November and April with community-acquired lower respiratory infection.

A review of the use of ribosomal DNA (rDNA) to differentiate among cryptic Anopheles species

Abstract: Cryptic species complexes are groups of closely related species that are difficult or impossible to distinguish by morphological traits. These complexes are known from a wide variety of arthropods and are common among the well-studied, medically-important insects. For example, many of the anopheline vectors of malaria parasites are members of cryptic species complexes. Complexes typically include both vector and non-vector species, and two or more member species are often found sympatrically. Until the late 1950, only two such Anopheles complexes were known, the A. gambiae complex from Africa and the A. maculipennis complex from Europe. Today, dozens of Anopheles cryptic species complexes are recognized, and accumulating evidence suggests that most important malaria vectors are likely to be members of such complexes. A variety of methods have been developed for identifying the species of individual specimens from these complexes, although until recently only those based on species-specific allozymes and polytene chromosome inversions were widely used. The limitations inherent in these methods have been circumvented with DNA-based procedures, which are especially useful because both sexes and all developmental stages can be identified, and DNA can be recovered from samples stored by a wide variety of simple methods. Several DNA-based identification techniques have been developed, including hybridization assays based on species-specific repeat sequences, and diagnostic PCR fragments produced either by the use of random PCR primers or by amplifying DNA with primers based on known species-specific sequences. In this review we discuss the relative marks of different methods of cryptic species identification, with emphasis on the use of ribosomal DNA as a target for species-diagnostic PCR assays.

Adverse pregnancy outcomes: differences between US- and foreign-born women in major US racial and ethnic groups.

Abstract: OBJECTIVES: This study examined whether there were significant differentials between US-born and foreign-born women in risks of infant mortality, low birthweight, and preterm birth and whether these differentials, if they existed, varied across major US racial/ethnic groups. METHODS: Multivariate logistic regression was applied to national linked birth/infant death records for 1985 through 1987 to estimate overall and ethnic-specific maternal nativity effects on pregnancy outcomes. RESULTS: Substantial maternal nativity differences in risks of infant mortality and low birthweight were found, with the magnitude of the nativity effect varying significantly across racial/ethnic groups. Overall, foreign-born status was associated with 7% and 20% lower risks of low birthweight and infant mortality, respectively. However, the reduced risk of adverse pregnancy outcome associated with immigrant status tended to be substantially larger for Blacks, Cubans, Mexicans, and Chinese than for other ethnic groups. CONCLUS...

Origin and interstate spread of a New York City multidrug-resistant Mycobacterium tuberculosis clone family

Abstract: Objective. —To determine whether isolates of Mycobacterium tuberculosis from New York and elsewhere that are resistant to four or more primary antimicrobial agents and responsible for widespread disease in the 1990s represent a newly emerged clone or a heterogeneous array of unrelated organisms. Setting. —New York City area and selected locations in the United States. Patients. — M tuberculosis isolates from 1953 patients in New York and multidrug-resistant isolates from six patients from other US communities. Design. —Convenience sample of all M tuberculosis strains ( M tuberculosis isolates resistant to rifampin, streptomycin, isoniazid, and ethambutol, and sometimes ethionamide, kanamycin, capreomycin, or ciprofloxacin) submitted to the Public Health Research Institute Tuberculosis Center since 1991 and samples submitted to the Centers for Disease Control and Prevention from throughout the United States. The samples submitted were representative of the New York City strains of M tuberculosis . Main Outcome Measure. —Characterization of resistant M tuberculosis strains studied by IS 61 10 and polymorphic GC-rich repetitive sequence (PGRS) hybridization patterns, multiplex polymerase chain reaction (PCR) analysis, and automated DNA sequencing of genes containing mutations associated with resistance to rifampin ( rpoB ), isoniazid ( katG and inhA locus), and streptomycin ( strA and rrs ). Results. —Multidrung-resistant M tuberculosis isolates were recovered from 253 New York City patients and had the same or closely allied IS 6110 and PGRS patterns, multiplex PCR type, and gene mutations associated with resistance to rifampin, isoniazid, and streptomycin. Isolates with these same molecular characteristics were recovered from patients in Florida and Nevada, health care workers in Atlanta, Ga, and Miami, Fla, and an individual who recently moved from New York City to Denver, Colo, and caused disease or skin test conversion in at least 12 people in a nursing home environment. Conclusions. —The results document the molecular origin and spread of progeny of a closely related family of multidrug-resistant M tuberculosis strains that have recently shared a common ancestor and undergone clonal expansion. The multidrug-resistant phenotype in these organisms arose by sequential acquisition of resistance-conferring mutations in several genes, most likely as a consequence of antibiotic selection of randomly occurring mutants in concert with inadequately treated infections. Dissemination of these difficult-to-treat bacteria throughout New York City and to at least four additional US cities has adverse implications for tuberculosis control in the 21st century. ( JAMA . 1996;275:452-457)

Virus isolation and quantitation

Abstract: Publisher Summary This chapter outlines the two most commonly used methods of virus isolation—namely, tissue cultures and embryonated eggs. The chapter describes the methodology involved for the predominant virus groups that cover the majority of viruses encountered in the clinical situation. The chapter also describes selected methods of virus assay and the calculation of virus titers. Nasal swabs are the easiest specimens to collect for respiratory viruses and are also the best specimens for the majority of the respiratory viruses described in the chapter. Hemadsorption is a fast and convenient method of detecting orthomyxoviruses and non respiratory syncytial virus paramyxoviruses in cell cultures in which the cytopathic effect vary from obvious to minimal.