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Biomedical subjects

S C Hadler

Publications and source records attributed to S C Hadler.

At least 55 records · Page 3Linked to original sources
PubMed1992

The geographic distribution of measles in the United States, 1980 through 1989.

OBJECTIVE: To describe the geographic distribution of measles cases in the United States by county for the 10-year period from 1980 through 1989. DESIGN: Ecological analysis of national measles surveillance data. METHODS: Measles cases reported to the Morbidity and Mortality Weekly Report from 1980 through 1989 were analyzed. Data from the 1980 and 1990 US censuses were used to produce demographic profiles for each of the 3137 countries. Outcome variables examined included mean annual incidence and number of years reporting measles, with use of Spearman's rank correlation coefficients to examine the association between the demographic and the two outcome variables. RESULTS: A total of 56,775 measles cases were reported during the decade. Of the nation's 3137 counties, 1690 (53.9%) did not report any cases; only 17 (0.5%) reported measles in all 10 years. Counties reporting measles more frequently during the decade had higher median populations, population densities, and percentage of black and Hispanic populations than those counties reporting less frequently. Population size, population density, and percentage of Hispanic population were associated with number of years reporting measles and mean annual measles incidence rate. Measles cases in counties reporting measles every year predominantly occurred in unvaccinated preschoolers; cases in counties reporting less frequently predominantly occurred in vaccinated school-aged children. CONCLUSIONS: This analysis illustrates the focal nature of measles in the United States during the past decade. Most counties have not reported a single case of measles during the entire decade, and only 17 counties reported measles every year. Targeted strategies are needed to improve age-appropriate immunization levels among preschool-aged children living in large inner-city areas.

Adolescent↗
PubMed1992

Measles herd immunity. The association of attack rates with immunization rates in preschool children.

OBJECTIVE: To examine the association between incidence of measles and immunization coverage among preschool-age children. DESIGN: An ecological study in which measles incidence was compared with immunization coverage among census tracts. The independent effects of race and population density were controlled for. SETTING: A recent measles outbreak in Milwaukee, Wis. Immunization coverage data were estimated from a retrospective, school-based survey of Milwaukee grade school students. PATIENTS: One thousand eleven persons (less than or equal to 17 years) who had confirmed measles from September 1989 through June 1990. MAIN OUTCOME MEASURES: Confirmed measles cases grouped by census tract, corresponding census tract preoutbreak immunization coverage, racial breakdown, and population density. RESULTS: Census tracts stratified into four levels, with mean immunization rates of 50.4%, 60.2%, 69.9%, and 81.0%, had respective median attack rates of 11.6, 5.0, 1.7, and 0.0 cases per 1000 persons (P less than .01). The association between immunization coverage and measles attack rate remained significant even after controlling for race and population density. CONCLUSIONS: Modest improvements in low levels of immunization coverage among 2-year-olds confer substantial protection against measles outbreaks. Coverage of 80% or less may be sufficient to prevent sustained measles outbreaks in an urban community.

Adolescent↗
PubMed1991

Intradermal hepatitis B vaccination in a large hospital employee population.

The intradermal route of hepatitis B vaccine administration has been tested in several clinical trials and has produced various degrees of immunogenicity, but usually among small groups of participants. To assess more adequately the immunogenicity of hepatitis B vaccine using the intradermal route, the Centers for Disease Control conducted a clinical trial among 425 well health-care workers in a hospital setting. Participants were randomly assigned to one of two treatment groups: those receiving a 20 micrograms intramuscular injection, and those receiving a 2 micrograms intradermal injection. Participants received the plasma-derived hepatitis B vaccine by the standard schedule at 0, 1 and 6 months, and serum samples were collected at 3, 8, 12 and 24 months after the first dose. Antibody response rates (anti-HBs titre greater than or equal to 10 sample ratio units by radioimmunoassay) for the intradermal vaccination group were consistently lower than those for the intramuscular vaccination group at each testing interval. The differences were greatest for the 3-month test and decreased over time. Geometric mean titres for anti-HBs for the intradermal group were significantly lower than those for the intramuscular group at the 8-month test point. In addition to inoculation route, factors of gender, smoking and age were found to have significant effects on immune response. The results suggest that intradermal vaccination with hepatitis B vaccine may be appropriate under certain conditions and for certain population subgroups.

Adult↗
PubMed1991

Hepatitis B: evolving epidemiology and implications for control.

Control and the possible elimination of transmission of HBV infection is possible with the appropriate use of hepatitis B vaccines. The prevention of chronic HBV infection has the potential of reducing the association burden of chronic liver disease and primary hepatocellular carcinoma. Worldwide, strategies for the effective use of hepatitis B vaccine have been developed and are being implemented in those areas where childhood transmission is the predominant source of chronic HBV infections. However, in the United States and other areas with "low" rates of HBV infection, current vaccination strategies have not been effective and have not fully taken into account the multifaceted epidemiology of HBV infection in those areas. Unfortunately, the majority of infections occur among adults who have been the most difficult to access, who acquire infection before they realize they are at risk, and where the changing epidemiology of HBV infections among the various risk groups only emphasizes the problems of vaccine delivery. In addition, the majority of persons receiving vaccine as a result of the current strategy to immunize adult high-risk groups have been persons who acquire HBV infection through occupational exposure, a group that accounted for no more than 5% of cases even before vaccine was introduced. The failure of the current immunization strategy to prevent a disease with significant health care and economic consequences is beginning to cause a reevaluation of this approach. A comprehensive approach to eliminating HBV transmission must address infections acquired during early childhood as well as those acquired by teenagers and adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Outcome of hepatitis B virus infection in homosexual men and its relation to prior human immunodeficiency virus infection.

To investigate the effect of human immunodeficiency virus type 1 (HIV-1) infection on subsequent hepatitis B virus (HBV) infection, HIV antibody was sought in homosexual men who developed HBV infection during a hepatitis B vaccine trial. Among 134 unvaccinated HIV-1-negative men, 7% became HBV carriers, 64% had viremia, and 42% had clinical illness. Among vaccinated HIV-1-negative men, HBV infection severity decreased with number of vaccine doses administered. When adjusted for prior hepatitis B vaccination status, persons with HIV-1 infection preceding HBV infection had a significantly higher risk of developing HBV carriage, viremia, prolonged ALT elevation, and clinical illness. Among HIV-1-infected men, the risk of HBV carriage was increased in unvaccinated persons (21%) and those who failed to respond to vaccination (31%) and further increased in those who received vaccine doses at the time they developed new HBV infection (56%-80%), suggesting inactivated hepatitis B vaccine may temporarily impair the immune response to HBV infection in HIV-1-infected persons. HIV-1 infection was also associated with reduced alanine aminotransferase elevations during the first 36 months of follow-up of men who became HBV carriers.

Alanine Transaminase↗
PubMed1991

Hepatitis A outbreak in a neonatal intensive care unit: risk factors for transmission and evidence of prolonged viral excretion among preterm infants.

An outbreak of hepatitis A virus (HAV) infection in a neonatal intensive care unit (NICU) provided the opportunity to examine the duration of HAV excretion in infants and the mechanisms by which HAV epidemics are propagated in NICUs. The outbreak affected 13 NICU infants (20%), 22 NICU nurses (24%), 8 other staff caring for NICU infants, and 4 household contacts; 2 seropositive infants (primary cases) received blood transfusions from a donor with HAV infection. Risk factors for infection among nurses were care for a primary infant-case (relative risk [RR], 3.2), drinking beverages in the unit (odds ratio [OR], infinity), and not wearing gloves when taping an intravenous line (OR, 13.7). Among infants, risk factors were care by a nurse who cared for a primary infant-case during the same shift (RR, 6.1). Serial stool samples from infant-cases were tested for HAV antigen (HAV-Ag) by enzyme immunoassay and HAV RNA by nucleic acid amplification using the polymerase chain reaction. Infant-cases excreted HAV-Ag (n = 2) and HAV RNA (n = 3) 4-5 months after they were identified as being infected. Breaks in infection control procedures and possibly prolonged HAV shedding in infants propagated the epidemic in a critical care setting.

Adult↗
PubMed1991

Immunogenicity of low-dose intradermal recombinant DNA hepatitis B vaccine.

Low-dose intradermal vaccination with plasma-derived hepatitis B vaccine has been shown to give high rates of seroconversion at greatly reduced vaccine cost. We report a study comparing two groups given lower doses (1.0 or 1.5 microgram) of recombinant-derived vaccine intradermally with a control group given the standard intramuscular dose. Of the 132 randomized medical students and hospital employees, 95 completed the study. Rates of seroconversion and peak antibody titers were comparable, though antibody rose more slowly and fell somewhat faster in the intradermal groups. Increasing the intradermal dose did not improve response. Most intradermal vaccinees (80%) developed small (average 2 to 3 mm) areas of local induration, which faded slowly. Low-dose intradermal vaccination with recombinant hepatitis B vaccine results in high rates of seroconversion (greater than 90% in each protocol) at a cost that will allow individual practitioners and program with limited budgets to offer vaccination.

Adult↗
PubMed1990

Risk factors for acute non-A, non-B hepatitis in the United States and association with hepatitis C virus infection.

The Centers for Disease Control conducted intensive surveillance for acute non-A, non-B hepatitis in four sentinel counties over a 7-year period. Testing for antibody to hepatitis C virus was performed with the newly developed enzyme immunoassay. The incidence of non-A, non-B hepatitis remained relatively stable (average, 7.1 cases per 100,000, but there were significant changes in disease transmission patterns. The proportion of patients with a history of blood transfusion declined from 17% to 6%, but the proportion with a history of parenteral drug use increased from 21% to 42%. The proportion of patients with histories of sexual exposure (6%), household exposure (3%), occupational exposure to blood (2%), or hemodialysis (0.6%) did not change over time. Antibody to hepatitis C virus was found in 45% of patients within 6 weeks of onset of illness and in 68% of patients followed up for at least 6 months. Patients with no history of transfusions were just as likely to be positive for antibody to hepatitis C virus as patients with transfusion-associated hepatitis, indicating that hepatitis C virus is the major causative agent of all non-A, non-B hepatitis in the United States.

Acute Disease↗
PubMed1990

Epidemic transmission of enterically transmitted non-A, non-B hepatitis in Mexico, 1986-1987.

Outbreaks of acute hepatitis occurred in Huitzililla and Telixtac, two rural villages 70 miles south of Mexico City, Mexico, in late 1986. The first outbreak began in Huitzililla in June of that year, 1 month after the start of the rainy season. A census revealed 94 icteric case subjects, for an attack rate of 5%; two women died. Attack rates were higher for persons older than 15 years (10%) than for younger persons. A case-control study showed that illness was highly associated with water-related factors. The second outbreak began in August 1986 in Telixtac. There were 129 case subjects, for an attack rate of 6%; one woman died. Epidemiologic findings were similar to those in Huitzililla, except that most disease transmission was not linked to unsafe water sources. None of 62 case subjects in Huitzililla and only 2 of 53 case subjects in Telixtac tested had serological evidence for recent infection with hepatitis A or B. Two of eight stool samples from Huitzililla and one of the eight stool samples from Telixtac were positive by immune electron microscopy for 32- to 34-nm viruslike particles similar to those seen in cases of enterically transmitted non-A, non-B hepatitis from Asia. To our knowledge, these investigations document for the first time the epidemic transmission of enterically transmitted non-A, non-B hepatitis virus in the Americas.

Acute Disease↗
PubMed1990

The changing epidemiology of hepatitis B in the United States. Need for alternative vaccination strategies.

To determine trends in the incidence and epidemiology of acute hepatitis B in the United States we conducted intensive surveillance for viral hepatitis in four sentinel counties from October 1, 1981, to September 30, 1988. The overall incidence of hepatitis B remained relatively constant throughout the study period (average, 13.2 cases per 100,000 population), but disease transmission patterns changed significantly. The proportions of hepatitis B cases accounted for by homosexual activity and health care employment decreased 62% and 75%, respectively; the proportions of cases accounted for by parenteral drug use and heterosexual exposure increased 80% and 38%, respectively. The percentage of patients for whom no risk factor was identified (30% to 40%) did not change over time. These patients tended to belong to minority populations, and their socioeconomic level was low. The decline in the number of hepatitis B cases among homosexual men probably results from the modification of high-risk sexual behavior; the decline among health care workers is due mostly to hepatitis B immunization. The current strategy for prevention of hepatitis B, which targets high-risk groups for immunization, has failed to have a significant impact on the incidence of disease.

Acute Disease↗
PubMed1990

Hepatitis B virus infection and health care workers.

Hepatitis B virus (HBV) infection is the major occupational risk of health care workers, among whom HBV infection risk is 2 to 10-fold elevated above that of the general population. Risk is most clearly related to the degree of direct contact with human blood and body fluids, and to frequency of traumatic exposures in the workplace. Most exposures result from unsuspected asymptomatic HBV carriers, who represent 1 to 2% of hospitalized patients. Risk of HBV infection also varies with the frequency of HBV carriers in the patient population. In the USA, the annual number of new cases has been constant over the last decade, despite a 50% overall increase in acute HBV disease. Control of HBV in the work setting is based on universal precautions for exposure to human blood or body fluids, and hepatitis B vaccination. Increased attention to these recommendations appears to be reducing this problem in the USA.

Health Occupations↗
PubMed1990

Heterosexual transmission of hepatitis B virus in Belle Glade, Florida. Belle Glade Study Group.

A population-based serosurvey of human immunodeficiency virus in Belle Glade, FL, enabled evaluation of risk factors for hepatitis B virus (HBV) infection in this racially mixed community. Serum samples from 725 adults and 130 children were tested for markers of HBV infection, and histories of exposure to HBV were obtained by interview. The overall prevalence of past or present HBV infection was 26%; prevalence was 9% among whites, 5% among Hispanics, 30% among blacks, and 57% among Haitians. Prevalence of HBV infection was 3% in children aged 2-10 years and increased to 31% in adults greater than 17 years. Of adults seropositive for HBV, only 5% had homosexual partners or used parenteral drugs, but 47% had a positive serologic test for syphilis. Factors associated with HBV infection in adults were positive serologic test for syphilis (odd ratio [OR] = 3.1; 95% confidence limits [CL] = 2.0, 4.8), and having had two or more lifetime heterosexual partners (OR = 3.2; 95% CL = 1.6, 6.4). In this community, HBV infection was transmitted predominantly by heterosexual contact.

Adolescent↗
PubMed1990

Foodborne hepatitis A: evidence that microwaving reduces risk?

During July 1988, 68 persons in Chattanooga, Tennessee, developed serologically confirmed hepatitis A. Between 15 June and 3 July, 93% of case-patients ate at a specific restaurant compared with only 3% of the local community. An intravenous drug user who worked as a cook was identified as the source. A case-control study was done to identify the vehicle of transmission. Case-patients were more likely than controls to have eaten hamburger buns and pickles, the only foods routinely handled after cooking. Of the restaurant patrons included in the study, 12 microwaved their food before consumption; none developed clinical illness despite eating large amounts of food handled after cooking. Sandwiches that were not microwaved were significantly associated with illness (odds ratio = 9.6; P less than .02). This epidemiologic evidence suggests that microwaves inactivate hepatitis A virus in food.

Adolescent↗