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B P Bell

Publications and source records attributed to B P Bell.

At least 19 recordsLinked to original sources
PubMed2005

Person-to-person transmission of hepatitis A virus in an urban area of intermediate endemicity: implications for vaccination strategies.

Developing countries with an increasing hepatitis A disease burden may target vaccination to specific groups, such as young children, as an initial control strategy. To better understand transmission of hepatitis A virus in such countries, the authors prospectively studied household and day-care/school contacts of cases in Almaty, Kazakhstan. Overall, by the time of identification of symptomatic index cases, half of transmission had already occurred, having been detected retrospectively. The odds of household contacts' becoming infected were 35.4 times those for day-care/school contacts (95% confidence interval (CI): 17.5, 71.7). Within households, younger age of either index cases or susceptible contacts elevated the odds of secondary infection among susceptible contacts: The presence of a case under 6 years of age raised the odds 4.7 times (95% CI: 1.2, 18.7); and compared with contacts aged 14 years or older, the odds of infection were increased to 7.7 (95% CI: 1.5, 40.3) and 7.0 (95% CI: 1.4, 34.3) among contacts aged 0-6 years and 7-13 years, respectively. Young children are appropriate targets for sustainable hepatitis A vaccination programs in areas undergoing hepatitis A epidemiologic transition. If vaccine is determined to be highly effective postexposure and if it is feasible, vaccinating household contacts could be a useful additional control strategy.

Adolescent↗
PubMed2005

The increasing prominence of household transmission of hepatitis A in an area undergoing a shift in endemicity.

In the rapidly developing city of Almaty, Kazakhstan, rates of hepatitis A have fallen, but no data on prevalence of antibody to hepatitis A virus (anti-HAV) exist with which to interpret incidence data. In the autumn of 2001, we determined the anti-HAV prevalence among household and school contacts of hepatitis A cases. For contacts aged 0-4 years, 5-9 years, 10-14 years, 15-19 years, or 20-30 years, immune prevalences were 9, 12, 33, 33 and 77% respectively, among immediate-family household contacts and 15, 28, 49, 52 and 77% respectively, among community contacts. Child community contacts were more likely to be immune than their immediate-family household counterparts (odds ratio 2.0, 95% confidence interval 1.3-3.2). Almaty is experiencing an epidemiological shift in hepatitis A incidence. Feasible and effective prevention strategies using hepatitis A vaccine should be explored.

Adolescent↗
PubMed2004

Viral hepatitis transmission in ambulatory health care settings.

In the United States, transmission of viral hepatitis from health care-related exposures is uncommon and primarily recognized in the context of outbreaks. Transmission is typically associated with unsafe injection practices, as exemplified by several recent outbreaks that occurred in ambulatory health care settings. To prevent transmission of bloodborne pathogens, health care workers must adhere to standard precautions and follow fundamental infection-control principles, including safe injection practices and appropriate aseptic techniques. These principles and practices need to be made explicit in institutional policies and reinforced through in-service education for all personnel involved in direct patient care, including those in ambulatory care settings. The effectiveness of these measures should be monitored as part of the oversight process. In addition, prompt reporting of suspected health care-related cases coupled with appropriate investigation and improved monitoring of surveillance data are needed to accurately characterize and prevent health care-related transmission of viral hepatitis.

Ambulatory Care↗
PubMed2001

Control of hepatitis A through routine vaccination of children.

CONTEXT: The impact of routine hepatitis A vaccination of children living in large communities with elevated disease rates has not been evaluated. OBJECTIVE: To determine the effect of routine vaccination of children on disease incidence in a community with recurrent hepatitis A epidemics. DESIGN, SETTING, AND PARTICIPANTS: Community-based demonstration project conducted from January 12, 1995, through December 31, 2000, in Butte County, California, among children aged 2 to 17 years. INTERVENTION: In 1995, vaccination was offered to children aged 2 to 12 years during vaccination clinics conducted on 2 occasions 6 to 12 months apart at most schools in the county. In 1996-2000, vaccine was distributed to community health care clinicians, who vaccinated eligible children without charge. Vaccine was also available at health department clinics, selected child care centers, and other sites. MAIN OUTCOME MEASURES: Hepatitis A vaccination coverage, hepatitis A incidence, and vaccine effectiveness. RESULTS: During the study period, 29 789 (66.2%) of an estimated 44 982 eligible children received at least 1 vaccine dose; 17 681 (39.3%) received a second dose. The number of hepatitis A cases among the entire county population declined 93.5% during the study period, from 57 cases in 1995 to 4 in 2000, the lowest number of cases reported in the county since hepatitis A surveillance began in 1966. The 2000 incidence rate of 1.9 per 100 000 population was the lowest of any county in the state. Of the 245 cases reported during the 6-year period, 40 (16.3%) occurred among children 17 years of age or younger, of which 16 (40%) occurred in 1995 and only 1 in 2000. One of the 27 case patients eligible for vaccination had been vaccinated, having received the first dose 3 days before symptom onset. The estimated protective vaccine efficacy was 98% (95% confidence interval, 86%-100%). CONCLUSIONS: In this population, hepatitis A vaccine was highly effective in preventing disease among recipients. Childhood vaccination appears to have decreased hepatitis A incidence among children and adults and controlled the disease in a community with recurrent epidemics.

Adolescent↗
PubMed2001

Hepatitis E virus antibody prevalence among persons who work with swine.

Prevalence of antibody and risk factors to hepatitis E virus (HEV) infection were determined in a cross-sectional study of 2 group-matched populations: swine farmers (n=264) and persons without occupational exposure to swine (n=255) in Moldova, a country without reported cases of hepatitis E. The prevalence of HEV infection was higher among swine farmers than among the comparison group (51.1% vs. 24.7%; prevalence ratio, 2.07; 95% confidence interval [CI], 1.62-2.64). In multivariate analysis, HEV infection was associated with an occupational history of cleaning barns or assisting sows at birth (odds ratio [OR], 2.46; 95% CI, 1.52-4.01), years of occupational exposure (OR, 1.04 per year; 95% CI, 1.01-1.07), and a history of drinking raw milk (OR, 1.61; 95% CI, 1.08-2.40). HEV infection was not associated with civilian travel abroad or having piped water in the household. The increased prevalence of HEV infection among persons with occupational exposure to swine suggests animal-to-human transmission of this infection.

Agricultural Workers' Diseases↗
PubMed2001

An outbreak of hepatitis A associated with green onions.

Forty-three cases of serologically confirmed hepatitis A occurred among individuals who ate at restaurant A in Ohio in 1998. Serum samples from all restaurant A employees who worked during the exposure period were negative for IgM antibodies to hepatitis A virus (HAV). A matched case-control study determined that foods containing green onions, which were eaten by 38 (95%) of 40 case patients compared with 30 (50%) of 60 control subjects, were associated with illness (matched odds ratio, 12.7; 95% confidence interval, 2.6-60.8). Genetic sequences of viral isolates from 14 case patients were identical to each other and to those of viral isolates from 3 patients with cases of hepatitis A acquired in Mexico. Although the implicated green onions, which could have come from one of 2 Mexican farms or from a Californian farm, were widely distributed, no additional green onion-associated cases were detected. More sensitive methods are needed to detect foodborne hepatitis A. A better understanding of how HAV might contaminate raw produce would aid in developing prevention strategies.

California↗
PubMed2001

A prevalence study of hepatitis A virus infection in a migrant community: Is hepatitis A vaccine indicated?

BACKGROUND: The Advisory Committee on Immunization Practices recommends routine hepatitis A vaccination of children living in communities with high rates of hepatitis A. Rates among children living in migrant farm worker families are unknown. METHODS: Participants recruited from the 1243 migrant children aged 2 to 18 years in Okeechobee County, Florida, were administered a questionnaire. A blood sample was taken for testing for antibodies to hepatitis A virus (anti-HAV), and hepatitis A vaccine was administered. RESULTS: Of 244 (20%) participating children, 125 (51%) were anti-HAV-positive. Seropositivity increased with age from 34% (2- to 5-year-olds) to 81% (>/=14-year-olds) (P <.0001). In multivariate analysis, age (odds ratio [OR] = 1.2/year; 95% CI = 1.1 to 1.3), having a Mexican-born father (OR = 12.2; 95% CI = 2.2 to 227.9), and age on moving to the United States (OR = 1.3/year; 95% CI = 1.0 to 1.6) were independently associated with anti-HAV positivity. Among US-born children aged 2 to 5 years who had never left the United States, 33% were anti-HAV-positive. CONCLUSIONS: Anti-HAV prevalence among migrant children in Okeechobee County, including the youngest US-born children, is high, indicating ongoing transmission of HAV. Children in this and other US migrant communities may benefit from hepatitis A vaccination.

Adolescent↗
PubMed2001

The role of child care in a community-wide outbreak of hepatitis A.

OBJECTIVE: To evaluate the role of child care centers in a community-wide hepatitis A epidemic. METHODS: We analyzed surveillance data during an epidemic in Maricopa County, Arizona, from January to October 1997 and conducted a case-control study using a sample of cases reported from June to November. Cases were physician-diagnosed and laboratory confirmed; control subjects were frequency matched by age and neighborhood. Information regarding hepatitis A risk factors, including child care-related exposures, was collected. Characteristics of all licensed child care centers in the county were obtained through review of computerized lists from the Arizona Office of Child Day Care Licensing. Surveillance data were linked to the child care list to determine which centers had reported hepatitis A cases. We conducted univariate and multivariate conditional logistic analyses and calculated population attributable risks (PAR). RESULTS: In total, 1242 cases (50/100 000 population) were reported. The highest rates occurred among people aged 0 to 4 (76/100 000), 5 to 14 (95/100 000), and 15 to 29 (79/100 000) years. The most frequently reported risk factor was contact with a hepatitis A patient (45%). However, nearly 80% of these contacts were with individuals who attended or worked in a child care center. Overall, child care center-related contact could have been the source of infection for 34% of case-patients. In the case-control study, case-patients (n = 116) and control subjects (n = 116) did not differ with respect to demographic characteristics. A total of 51% of case-patients compared with 18% of control subjects reported attending or working in a child care setting (direct contact; adjusted odds ratio [OR]: 6.0; 95% confidence interval [CI]: 2.1-23.0) or being a household contact of such a person (indirect contact; OR: 3.0; 95% CI: 1.3-8.0). In age-stratified analyses, the association between hepatitis A and direct or indirect contact with child care settings was strongest for children <6 years old and adults aged 18 to 34 years. Household contact with a person with hepatitis A also was associated with hepatitis A (OR: 9.2; 95% CI: 2.6-58.2). The presence of a child <5 years old in the household was not associated with hepatitis A. The estimated PAR for direct child care contact was 23% (95% CI: 16-34), for indirect child care contact was 21% (95% CI: 13-35), and for any child care contact was 40% (95% CI: 30-53). Information on 1243 licensed child care centers was obtained, with capacity ranging from 5 to 479 slots (mean: 87). Thirty-four (2.7%) centers reported hepatitis A cases. Centers that had a mean capacity of >50 children were more than twice as likely to have had a reported case of hepatitis A (OR: 2.6; 95% CI: 1.1-6.7). Among the 747 centers that accepted >50 children, having infant (OR: 3.7; 95% CI: 1.6-8.3), toddler (OR: 6.3; 95% CI: 2.2-20.0), or full-day service (OR; undefined; 95% CI: 1.7- ~) was associated with having a reported case of hepatitis A. CONCLUSIONS: In Maricopa County, people associated with child care settings are at increased risk of hepatitis A, and child care attendees may be an appropriate target group for hepatitis A vaccination. Considering the estimated proportion of children who attended child care and were old enough to receive hepatitis A vaccine (>/=2 years of age) and the calculated PAR, approximately 40% of cases might have been prevented if child care center attendees and staff had been vaccinated. However, epidemiologic studies indicate that the proportion of cases that are attributable to child care center exposure varies considerably among counties, suggesting that this exposure may be associated with an increased risk of hepatitis A in some communities but not in others. To prevent and control hepatitis A epidemics in communities, the Advisory Committee on Immunization Practices and the American Academy of Pediatrics have adopted a long-term strategy of routine vaccination of children who live in areas with consistently elevated hepatitis A rates. After demonstrating cost-effectiveness, a rule was implemented in January 1999 to require hepatitis A vaccination of all children who are aged 2 to 5 years and enrolled in a licensed child care facility in Maricopa County. Other communities with similar epidemiologic features might consider routine vaccination of child care center attendees as a long-term hepatitis A prevention strategy. Consistent with current recommendations, in communities with persistently elevated hepatitis A rates where child care center attendance does not play an important role in hepatitis A virus transmission in the community, child care centers may nonetheless provide a convenient access point for delivering hepatitis A as well as other routine childhood vaccinations.

Adolescent↗
PubMed2000

Multiple modes of hepatitis A virus transmission among methamphetamine users.

Methamphetamine users are at increased risk of hepatitis A, but modes of transmission are unclear. The authors conducted a case-control study among methamphetamine users during an outbreak in Iowa in 1997. Twenty-eight reported, laboratory-confirmed, hepatitis A cases did not differ from 18 susceptible controls with respect to age, sex, or number of doses used. When compared with controls in multivariate analysis, case-patients were more likely to have injected methamphetamine (odds ratio (OR) = 5.5, 95% confidence interval (CI): 1.1, 27), to have used methamphetamine with another case-patient (OR = 6.2, 95% CI: 0.95, 41), and to have used brown methamphetamine (OR = 5.5, 95% CI: 0.51, 59). Receptive needle sharing was reported by 10 of the 20 case-patients who injected. Methamphetamine use with another case-patient was also associated with hepatitis A in an analysis restricted to noninjectors (OR = 17, 95% CI: 1.0, 630). During this outbreak, hepatitis A may have been transmitted from person to person among methamphetamine users through the fecal-oral and the percutaneous routes. Methamphetamine users should be vaccinated against hepatitis A and should be given immune globulin if they used methamphetamine with a case-patient in the last 2 weeks. Persons who intend to continue using methamphetamine should be advised about safer practices.

Adolescent↗
PubMed2000

Hepatitis A vaccine.

Inactivated hepatitis A vaccines are highly immunogenic and efficacious. Because of their high disease rates and importance as a reservoir of transmission to others, children should be the primary focus of vaccination. A long-term strategy of sustained routine vaccination of children living in areas with consistently elevated hepatitis A rates has been adopted. Ultimately, elimination of HAV transmission will require vaccination of all children in the US. This effort would be facilitated by the availability of vaccine formulations or schedules for use in infants or children in the second year of life, and combination vaccines that include hepatitis A.

Adolescent↗
PubMed2000

Prevalence of antibody to hepatitis A virus in drinking water workers and wastewater workers in Texas from 1996 to 1997.

To determine if wastewater workers had a higher prevalence of antibody to hepatitis A virus (anti-HAV) than drinking water workers, a convenience sample of Texas wastewater and drinking water workers was evaluated for risk factors by questionnaire and tested for anti-HAV. A total of 359 wastewater and 89 drinking water workers participated. Anti-HAV positivity was 28.4% for wastewater and 23.6% for drinking water workers. After adjustment for age, educational attainment, and Hispanic ethnicity, the odds ratio for the association between anti-HAV positivity and wastewater industry employment was 2.0 (95% confidence interval, 1.0 to 3.8). Among wastewater workers, never eating in a lunchroom, > or = 8 years in the wastewater industry, never wearing face protection, and skin contact with sewage at least once per day were all significantly associated with anti-HAV positivity in a model that adjusted for age and educational attainment. Wastewater workers in this study had a higher prevalence of anti-HAV than drinking water workers, which suggested that wastewater workers may have been at increased risk of occupationally acquired hepatitis A. Work practices that expose workers to wastewater may increase their risk.

Adult↗
PubMed2000

Sources of infection among persons with acute hepatitis A and no identified risk factors during a sustained community-wide outbreak.

CONTEXT: Hepatitis A is a common vaccine-preventable disease in the United States. Most cases occur during community-wide outbreaks, which can be difficult to control. Many case-patients have no identified source. OBJECTIVE: To identify foodborne and household sources of hepatitis A during a community-wide outbreak. DESIGN: Serologic and descriptive survey. SETTING: Salt Lake County, Utah. PARTICIPANTS: A total of 355 household contacts of 170 persons reported with hepatitis A during May 1996 to December 1996, who had no identified source of infection; and 730 food handlers working in establishments where case-patients had eaten. MAIN OUTCOME MEASURE: Prevalence of immunoglobulin M antibodies to hepatitis A virus (IgM anti-HAV) among household and food service contacts. RESULTS: Overall, 70 household contacts (20%) were IgM anti-HAV-positive, including 52% of children 3 to 5 years old and 30% of children <3 years old. In multivariate analysis, the presence of a child <3 years old (odds ratio [OR]: 8.8; 95% confidence limit [CL]: 2.1,36) and a delay of >/=14 days between illness onset and reporting (OR: 7. 9; 95% CL: 1.7,38) were associated with household transmission. Of 18 clusters of infections linked by transmission between households, 13 (72%) involved unrecognized infection among children <6 years old. No food handlers were IgM anti-HAV-positive. CONCLUSION: During a community-wide outbreak, HAV infection among children was common, was frequently unrecognized, and may have been an important source of transmission within and between households. Transmission from commercial food establishments was uncommon. Ongoing vaccination of children may prevent future outbreaks.

Acute Disease↗
PubMed1999

A multistate, foodborne outbreak of hepatitis A. National Hepatitis A Investigation Team.

BACKGROUND: We investigated a large, foodborne outbreak of hepatitis A that occurred in February and March 1997 in Michigan and then extended the investigation to determine whether it was related to sporadic cases reported in other states among persons who had consumed frozen strawberries, the food suspected of causing the outbreak. METHODS: The cases of hepatitis A were serologically confirmed. Epidemiologic studies were conducted in the two states with sufficient numbers of cases, Michigan and Maine. Hepatitis A virus RNA detected in clinical specimens was sequenced to determine the relatedness of the virus from outbreak-related cases and other cases. RESULTS: A total of 213 cases of hepatitis A were reported from 23 schools in Michigan and 29 cases from 13 schools in Maine, with the median rate of attack ranging from 0.2 to 14 percent. Hepatitis A was associated with the consumption of frozen strawberries in a case-control study (odds ratio for the disease, 8.3; 95 percent confidence interval, 2.1 to 33) and a cohort study (relative risk of infection, 7.5; 95 percent confidence interval, 1.1 to 53) in Michigan and in a case-control study in Maine (odds ratio for infection, 3.4; 95 percent confidence interval, 1.0 to 14). The genetic sequences of viruses from 126 patients in Michigan and Maine were identical to one another and to those from 5 patients in Wisconsin and 7 patients in Arizona, all of whom attended schools where frozen strawberries from the same processor had been served, and to those in 2 patients from Louisiana, both of whom had consumed commercially prepared products containing frozen strawberries from the same processor. CONCLUSIONS: We describe a large outbreak of hepatitis A in Michigan that was associated with the consumption of frozen strawberries. We found apparently sporadic cases in other states that could be linked to the same source by viral genetic analysis.

Adolescent↗
PubMed1999

Identifying target groups for a potential vaccination program during a hepatitis A communitywide outbreak.

OBJECTIVES: This study sought to identify groups for targeted vaccination during a communitywide hepatitis A outbreak in 1996. METHODS: Residents of the Sioux City, Iowa, metropolitan area reported with hepatitis A between September 1995 and August 1996 were sampled and compared with population-based controls. RESULTS: In comparison with 51 controls, the 40 case patients were more likely to inject methamphetamine, to attend emergency rooms more often than other health care facilities, and to have a family member who used the Special Supplemental Nutrition Program for Women, Infants, and Children. CONCLUSIONS: Groups at increased risk of hepatitis A can be identified that might be [corrected] accessed for vaccination during communitywide outbreaks.

Adult↗
PubMed1998

Hepatitis A virus sequence detected in clotting factor concentrates associated with disease transmission.

Since the early 1990s hepatitis A virus (HAV) infections among recipients of solvent-detergent treated factor VIII concentrates have occurred in Europe, South Africa and the United States. A review of the epidemiological and laboratory-based investigations of the outbreaks in Germany and Ireland were consistent with transmission by factor concentrates but limited information about transmission based upon nucleic acid sequences was obtained, and no clear chain of transmission could be established. Within the United States, hepatitis A infections associated with solvent detergent concentrate occurred in a single patient in 1993, and a cluster of cases in 1995. Although the 1993 factor concentrate was positive for virus, samples from the patient were not available. The virus present in the cluster of 1995 factor VIII patients, the factor concentrate they received, and the original plasma pool was identical, while the virus identified in the factor IX patient differed by a single base.

Detergents↗
PubMed1998

Hepatitis A virus infections associated with clotting factor concentrate in the United States.

BACKGROUND: Two cases of hepatitis A among persons exposed to the same lot of solvent/detergent-treated antihemophilic factor VIII concentrate were reported to a surveillance system. An investigation was conducted to find additional cases and determine the source of infection. STUDY DESIGN AND METHODS: A seroprevalence study was conducted among persons with exposure to the suspect lot for serologic evidence of recent infection with hepatitis A virus (HAV). RESULTS: Six cases of recent HAV infection were discovered: four of the patients had been infused with material from the suspect lot of factor VIII, and two had received infusions of factor IX concentrate made from plasma pools common to the suspect factor VIII lot. HAV was identified in one of the plasma pools, in the factor VIII product, and in serum or stool from two factor VIII recipients and one factor IX recipient. The genetics sequence of the virus in the plasma pool, the factor VIII lot, and the factor VIII recipients were identical, while that of the virus in the factor IX recipient differed by a single base. CONCLUSION: These data document the transmission of HAV by a factor VIII concentrate and implicate factor IX products manufactured from a common source-plasma pool.

Adolescent↗