Salivary antibody testing in a school outbreak of hepatitis A.

During a community-wide outbreak of hepatitis A in Gloucester, UK there was a high attack rate in children attending two city primary schools and a pre-school centre sharing the same site. In September 1990, saliva specimens were collected from 478 (85%) of the 562 children. The prevalence of antibody to hepatitis A virus (anti-HAV), as determined by saliva testing, was 29.6%; highest prevalences were seen in 5-6-year-olds and in children from that area of the city at the centre of the community-wide outbreak. The proportion of immune children with a history of clinical hepatitis varied with age from 1 in 42.7 of under-5-year-olds to 1 in 4.7 of 8-10-year-olds. Six children who received prophylaxis with human normal immune globulin (HNIG) because they were household contacts of cases subsequently became infected. Since there was evidence of transmission outside the school environment it is unlikely that a policy of universal prophylaxis within the schools would have stopped the outbreak. Mass prophylaxis in school outbreaks is only likely to be effective if most transmission is occurring at school and if the target population can be clearly defined. Salivary antibody testing is a simple, practical and acceptable procedure in young children. Salivary antibody surveys in conjunction with vaccination against hepatitis A should provide a cost-effective method for control of future outbreaks.     

A Community-wide epidemic of hepatitis A in Ohio

Between June 1, 1983 and August 30, 1984, an epidemic involving 313 cases of hepatitis A occurred in Muskingum County, Ohio. One hundred ninety-seven cases occurred in the city of Zanesville, with 34.7% of cases concentrated in two neighborhoods in the eastern part of the city. Case characteristics were similar to those reported in previous community-wide outbreaks, including a maximum attack rate among 5-9-year-olds and a very low attack rate in adults over 30 years. Case households were larger, and their members were less educated than the mean for households in the city. Forty-eight per cent of the cases reported exposures to other cases which temporally could have been the source of infection. A case-control study failed to show differences in several behavioral factors between case and control households, but did confirm that lower socioeconomic status was a risk factor for the disease. Broad use of immunoglobulin was effective in preventing clinical disease among family contacts, but did not stop the outbreak. This outbreak typifies a genre of hepatitis A epidemic transmitted from person to person in which exact routes of spread are poorly understood and control is difficult. Lower socioeconomic status may be a marker for some unidentified behaviors that promote hepatitis A transmission.     

Protecting contacts of hepatitis A: what's the difference between vaccine and human normal immunoglobulin?

The efficacy of vaccine when time since exposure is prolonged (more than 1 week from onset of illness in the index case) is unknown, but is likely to be significantly lower than human normal immunoglobulin (HNIG). We estimated the number of additional secondary cases that may occur through giving vaccine instead of HNIG to contacts of cases of hepatitis A who are identified more than 1 week after onset in the index case. This was calculated for different levels of vaccine efficacy, assuming HNIG efficacy to be 80-90%. The number of households that need to be treated to prevent one secondary case was calculated using estimates of secondary attack ratios (AR). If more than 1 week has elapsed from onset of illness in the index case, for an average household size of 2.3 people, a vaccine efficacy of 50% and an AR of 10-25%, 8-26 households would need to be treated with vaccine before one additional secondary case would be observed. As UK public health professionals manage around one hepatitis A case per month, it would take from 8 months to over 2 years for them to observe one additional case amongst contacts using vaccine rather than HNIG. It is unlikely that an average practitioner would notice if vaccine were 30% less effective than HNIG. Public health practice and advice to patients and contacts should be based on evidence as well as experience.     

Long-term protective effect of post-exposure Havrix TM administration during viral hepatitis Type A outbreaks

Administration of human normal immunoglobulin (HNIG) post-exposure has been routinely used in Slovakia for outbreak control of hepatitis A, but requires deep intramuscular injection, provides only short-lived protection and is a human blood product. The protective effect of post-exposure administration of an inactivated hepatitis A vaccine was evaluated during 10 outbreaks in Slovakia. Direct contacts of confirmed hepatitis A cases received either: a single dose of hepatitis A vaccine (n = 2171) or immunoglobulin (HNIG, n = 3837). In the HNIG group the number of hepatitis A confirmed cases dropped within the first 7 weeks, however the decrease was not as rapid or as marked as that observed in the vaccinated group where the number of hepatitis A cases dropped within the first 4 weeks after vaccination. Among contacts, 67 cases of hepatitis A were detected during the maximum incubation period of 45 days: 16 cases (0.7%) in the vaccine group and 51 cases (1.3%) in the HNIG group (p  <  0.05). After two and three years respectively, 50 and 39 volunteers who had previously received one dose of hepatitis A vaccine received a booster dose and anti-HAV antibodies were measured. Differences in anti-HAV antibody GMCs before and after the booster were statistically significant. The longer time interval (3 years instead of 2) between primary vaccination and booster administration did not seem to impact the magnitude of the booster response. The results of this study show that active post-exposure immunisation with only one dose of inactivated vaccine confers high and long-term protection and effectively controls viral hepatitis A outbreaks.     

Active immunisation during an outbreak of hepatitis A in a German day-care centre

During an outbreak in a German day-care centre (DCC) caring for 100 children HAV vaccination was recommended for children, employees and household members of cases. A retrospective cohort study was done to evaluate vaccine uptake and identify possible risk factors for disease. Between 19 December 2004 and 30 January 2005 eight DCC children and seven household members fulfilled the case definition, i.e. had clinical hepatitis (14) or were diagnosed with asymptomatic HAV infection (1). Following the recommendation to vaccinate, given on 23 December 2004, 66.7% (46/69) of DCC children, 15.8% (29/184) of household members and 5/5 of employees were vaccinated, and three vaccinated children and two not vaccinated children fell ill. One of 11 children who received human normal immunoglobulin (HNIG) and four of 58 children who did not receive HNIG fell ill. In households in which the DCC child received HAV vaccine and/or HNIG, seven (5.6%) of 125 household members fulfilled the case definition. In households of non-immunised children none of the 59 household members fell ill. We conclude that, although most vaccinations were administered promptly, they may not have been timely enough to impact the course of the outbreak.     

A community-wide outbreak of hepatitis A in a religious community: impact of mass administration of immune globulin

Community-wide outbreaks of hepatitis A are frequently prolonged and difficult to control. An extensive outbreak of hepatitis A in a religious community provided an opportunity to assess the effect of mass administration of immune globulin on the course of the outbreak. Between July 1, 1988 and May 30, 1989, 204 cases occurred among 3,500 residents (58/1,000), with persons aged 5-19 years having the highest attack rate. It was found that 89% of persons older than age 19, but no persons under age 20, had evidence of prior hepatitis A infection. During a 5-day campaign, immune globulin (0.02 ml/kg) was administered to 2,287 (65%) of the 3,500 residents. The cost of vaccine and syringes was less than $3,500. New cases among immune globulin recipients virtually stopped 2 weeks after the campaign, and the incidence of hepatitis in the community decreased from 9.6/week to 1.9/week. Among persons younger than age 20 years, the efficacy of immune globulin was 88.9% (95% confidence interval 77.9-94.5) for seven months. Although the authors cannot be sure that the outbreak will not recur, they believe that mass administration of immune globulin appears to have been partially effective at controlling this community-wide outbreak.     

Experience of hepatitis A vaccination during an outbreak in a nursery school of Tuscany,Italy.

An outbreak of hepatitis A started in late October 1996 in a nursery school in Tuscany, Italy. A programme of hepatitis A vaccination without the use of immunoglobulin started at the beginning of December 1996 and included 33 children, 21 household contacts and 6 adults working in the school. Overall, 11 cases occurred in children attending the school (attack rate 27%) and 10 among their household contacts (attack rate 9 %). The latter also included parents, and, in two cases, grandmothers. The data indicate that susceptibility to HAV has increased over recent decades in central Italy. Past and recent experience shows that the usual duration of hepatitis A epidemics in the absence of immune prophylaxis is longer than that described here. The use of hepatitis A vaccine probably contributed to the early extinction of the outbreak, because no further cases were notified in the area after 7 February 1997.     

Hepatitis A surveillance in England--how many cases are not reported and does it really matter?

Underreporting of hepatitis A infection in England may be high and a number of outbreaks have occurred undetected by routine surveillance. We evaluated surveillance of hepatitis A cases by employing capture-recapture analysis on data from two distinct outbreaks of hepatitis A. The overall reporting of cases of hepatitis A was 81.7% (95% CI 55.3-95) in the first outbreak in North East England and reporting through Lab Base was 65.7% (95% CI 42.8-76.4). In the second outbreak in the East Midlands the overall reporting of hepatitis A cases was 27.8% (95% CI 19-38.7) and through Lab Base 16.6% (95% CI 11.4-23.1). Underreporting of hepatitis A cases is high. Public health interventions exist to prevent and control outbreaks of hepatitis A. The lack of reliable data on incidence and prevalence hampers effective public health management of this disease.     

The role of young children in a community-wide outbreak of hepatitis A.

An Hasidic Jewish community has experienced recurrent hepatitis A outbreaks since 1980. To assess risk factors for illness during a 1985-6 outbreak, the authors reviewed case records and randomly selected 93 households for an interview and serologic survey. In the outbreak, 117 cases of hepatitis A were identified, with the highest attack rate (4.2%) among 3-5 year olds. Among the survey households, the presence of 3-5 year olds was the only risk factor that increased a household''s risk of hepatitis A (indeterminant relative risk, P = 0.02). Furthermore, case households from the outbreak were more likely to have 3-5 years olds than were control households from the survey (odds ratio = 16.4, P < 0.001). Children 3-5 years old were more likely to have hepatitis A and may have been the most frequent transmitters of hepatitis A in this community. Hepatitis A vaccination of 3-5 year olds can protect this age group and might prevent future outbreaks in the community.     

2007～2009年大连市82起水痘暴发疫情分析

[目的]了解大连市水痘暴发疫情的流行情况,为制定水痘防制措施提供科学依据。[方法]对大连市2007～2009年报告的82起水痘暴发疫情资料进行分析。[结果]2007～2009年累计报告水痘暴发疫情82起,其中13起构成突发公共卫生事件,发病952例,暴发点平均罹患率为1.38%。2007～2009年分别发生14起、138例,32起、529例,36起、285例;发生暴发疫情最多的是甘井子区（21起）,发病最多的是甘井子区（274例）,平均罹患率最高的是中山区（3.05%）;发生暴发疫情最多的是小学（40起）,发病最多的是小学（544例）,平均罹患率最高的是托幼机构（4.99%）;春季、夏季、秋季和冬季分别发生26起、262例,35起、375例,9起、169例,12起、146例;952例病人中,男性557例,女性395例;0～4岁153例,5～9岁564例,10～14岁204例,≥15岁31例;托幼儿童339例,学生611例,其他人群2例。[结论]大连市的水痘暴发疫情主要发生在托幼机构,夏季多见。     

Costs of a hepatitis A outbreak affecting homosexual men: Franklin County, Ohio, 1999

BACKGROUND: Hepatitis A is one of the most commonly reported, vaccine-preventable diseases in the United States. Many cases occur in association with community-wide outbreaks, but societal costs to the community are seldom documented. METHODS: Hepatitis A case-patients available for a follow-up interview as part of an outbreak investigation were asked about hospitalization, healthcare costs, missed work, and lost wages associated with their illness, as well as healthcare insurance coverage and sick-leave reimbursement. Average costs were calculated by case-patient age, gender, and hospitalization status for lost wages, and by age and hospitalization status for medical costs, and then assigned to case-patients not re-interviewed to provide an estimate of overall costs. Health departments provided outbreak-associated costs. RESULTS: Between the weeks of November 2, 1998, and May 17, 1999, a total of 136 cases of hepatitis A were reported. Of the 89 (65.4%) case-patients available for interview, 74 (83%) were male; of those, 47 (64%) identified themselves as men who have sex with men (MSM). The average cost of the outbreak per case-patient was $2894 US dollars, of which 51% was associated with lost wages, 40% with medical costs, and 9% with health department costs. Case-patients incurred 44% of total outbreak costs; employers, 29%; healthcare insurers, 18%; and health departments, 9%. CONCLUSIONS: In this community-wide hepatitis A outbreak, case-patients incurred the largest portion of costs, followed by employers, healthcare insurers, and health departments.     

Continuing outbreak of hepatitis A linked with intravenous drug abuse in Multnomah County

A communitywide outbreak of hepatitis A occurred in Portland, OR, from 1983 through 1986. At the peak of the outbreak, the age- and sex-specific annual incidence rate approached 400 cases per 100,000 population among men ages 25 to 34, the highest risk group. The community incidence rate was nearly 10 times the relevant national incidence rate. A review of the records concerning cases of hepatitis A reported in the last 6 months of 1985 revealed that about half the number of young adults whose cases were investigated during that time reported a history of intravenous (IV) drug use--a proportion about 50 times greater than expected among persons in that age range. A simultaneous epidemic of overdose deaths from heroin and a concomitant increase in hepatitis B incidence rates led to the suspicion that this was a drug-abuse-associated epidemic of hepatitis among new IV drug users. Control of this outbreak was difficult because the population most at risk was distrustful of public health officials. Increased surveillance in food service establishments and schools might have prevented outbreaks from a common source in the general population; however, an increase of sporadic cases in the nondrug-using population clearly occurred.     

The risk of acquiring hepatitis from sewage-contaminated water

There is little information on the risk of acquiring hepatitis A from drinking sewage-contaminated water. In a large outbreak of gastrointestinal illness at Crater Lake National Park, Oregon, a US national park, in June-July, 1975, approximately 100,000 persons were exposed to sewage-contaminated water. State health departments reported three cases of Crater Lake-associated hepatitis A for a rate of 12/100,000 per year, comparable to the reported US incidence of non-B hepatitis 10/100,000 per year. Questionnaire survey of 3997 overnight park visitors revealed five cases of hepatitis A, occurring in 2206 persons who drank water but did not receive immune serum globulin (ISG) within two weeks of exposure, an attack rate of 0.23%. The association between drinking park water and subsequently developing hepatitis was not statistically significant. No cases of hepatitis occurred in 320 park staff and family members, repeatedly exposed to contaminated water. The authors do not recommend routine use of prophylactic ISG for similar outbreaks of gastroenteritis caused by sewage-contaminated water but suggest close surveillance of the exposed group, and careful consideration of risk factors and costs.     

Recurrent outbreaks of giardiasis in a child day care center, Wisconsin.

In the 19-month period September 1983-March 1985, three outbreaks of giardiasis occurred in one large child day care center. Control measures instituted during each outbreak included case finding; pharmacologic treatment and follow-up testing of stool specimens for cases of giardia infection in day care children and staff, and their household contacts; facilitating and stressing personal and environmental hygiene, including altering diapering practices and teaching appropriate hand washing techniques. In the first, second, and third outbreaks, overall attack rates (stool analysis positive for Giardia lamblia) were determined for those persons with greater than or equal to 2 stool specimens submitted; attack rates in children were 47, 17, and 37 per cent, respectively; for tested staff, the rates were 35, 13, and 9 per cent; and for tested household contacts were 18, 9, and 5 per cent. Attack rates were highest for ambulatory diapered children, children attending the day care center greater than or equal to 40 hours per week, and children who were infected with G. lamblia in the most recent previous outbreak. Despite extensive efforts to identify cases, a cure rate of greater than 90 per cent in treated cases, and improvements in personal and environmental hygiene practices, G. lamblia infections recurred in outbreak proportions.     

2009年大连市疫苗相关传染病暴发疫情分析

[目的]分析大连市疫苗相关传染病暴发疫情的流行病学特征。[方法]应用描述性流行病学方法对大连市2009年疫苗相关传染病暴发疫情进行分析。[结果]2009年大连市共报告疫苗相关传染病暴发疫情54起,其中1起构成突发公共卫生事件。共报告罹患病例432人,罹患率为0.95%。54起暴发疫情全部发生在学校,其中小学最多,发生26起,罹患234人。54起暴发疫情主要集中在3~6月,共报告45起,占总报告起数的83.33%。[结论]2009年报告疫苗相关传染病暴发疫情与2008年基本持平,罹患人数却下降了91.45%,托幼机构和学校是暴发疫情的高发场所,且以呼吸道传染病为主。     

An outbreak of hepatitis A associated with treated waste water used for irrigation

Hepatitis A virus (HAV) infection is endemic in developing countries and remains a public health problem elsewhere. This study was conducted to investigate an outbreak of HAV infection, which occurred during a period of almost 5 months (January-May 1996) in the National Guard Iskan (Housing Authority) in Jeddah, Saudi Arabia. Ninety four cases were found to be positive for IgM antibody to HAV. A case control study was done to identify possible risk factors. For every case, 3 controls have been selected from the same household matched for age and sex. Information about reported cases was obtained by attending physicians through an interview questionnaire from adult cases and parents of young cases and controls (<12 y). It included questions regarding symptoms, demographics and possible source of the infection. Results showed that the attack rate of the whole population was 1.03 %, while that for children <10 years was twofold higher (2.05 %) than the total population. The risk of acquiring infection among them was found to be five times that among those aged 40 years and higher (R.R=5.32). There was a lack of association between developing hepatitis A and any of the food items or milk used in the studied area during the time of the outbreak. On the other hand exposure to irrigation water among cases was found to be significantly higher than among controls especially among children below 10 years (O.R=2.26). Analysis of the available data suggests a strong association between illness and exposure to waste water used for irrigation of gardens through playing with it, or through occasional drinking especially among children below 10 years. The prolonged course of the outbreak (5 months) may be attributed to subsequent person to person transmission from index cases to intimate contacts especially among the same household.     

Management of hepatitis A in a food handler at a London secondary school

A case of hepatitis A in a food handler at a local secondary school prompted the institution of control measures including administration of human normal immunoglobulin (HNIG) to all pupils. This paper summarises the management of the incident and describes the use of HNIG to prevent secondary cases. Few adverse effects were reported and only one secondary case of hepatitis A occurred at the school.     

Outbreak of viral hepatitis B in a rural community in India linked to inadequately sterilized needles and syringes.

In India, virtually all outbreaks of viral hepatitis are considered to be due to faeco-orally transmitted hepatitis E virus. Recently, a cluster of 15 cases of viral hepatitis B was found in three villages in Gujarat State. The cases were epidemiologically linked to the use of inadequately sterilized needles and syringes by a local unqualified medical practitioner. The outbreak evolved slowly over a period of 3 months and was marked by a high case fatality rate (46.7%), probably because of concurrent infection with hepatitis D virus (HDV) or sexually transmitted infections. But for the many fatalities within 2-3 weeks of the onset of illness, the outbreak would have gone unnoticed. The findings emphasize the importance of inadequately sterilized needles and syringes in the transmission of viral hepatitis B in India, the need to strengthen the routine surveillance system, and to organize an education campaign targeting all health care workers including private practitioners, especially those working in rural areas, as well as the public at large, to take all possible measures to prevent this often fatal infection.     

Hepatitis A virus infection control: an audit of practice in England and Wales prior to guidelines being published

This survey was conducted in September 2001 to audit the practice of Consultants in Communicable Disease Control (CsCDC) and to gain a systematic picture of pre-guideline approaches to the control of hepatitis A virus infection in England and Wales. An audit form was distributed to all CsCDC by email and responses were entered in a database and analysed. Response rate is estimated at 44%. CsCDC predominantly recommend vaccination for prevention. For 31% of the CsCDC, index cases were not reported within a week of the onset of illness. As a result, vaccine was often used sub-optimally. By contrast 95% of the CsCDC were informed of an index case within two weeks of onset of illness, in time for effective use of human normal immunoglobulin (HNIG). CsCDC were cautious in the use of HNIG for a number of reasons including concerns about variant Creutzfeldt-Jacob Disease (vCJD). A substantial proportion (between 5% and 28% for different age groups) of CsCDC did not recommend any active prevention among close family contacts of a case. Important ways to improve practice include facilitating use of HNIG and speeding up reporting by doctors and laboratories.     

Exposure to school children as a risk factor in a community outbreak of hepatitis A in young adults: a case control study

To investigate risk factors during a community outbreak of hepatitis A we carried out a case- control study of 35 cases and 49 matched controls using an interviewer-administered questionnaire on clinical history, travel, household details including domestic toilet facilities, infectious contacts, and food history. Of 99 cases notified in the city during the outbreak year, 50 (51%) were young adults age 15-34 years. Hepatitis A infection was independently associated with household contact with a case (P=0.0005), and sharing a household with children in primary school (OR 3.4, 95% CI 1.2-9.5, P=0.008) with risk increasing with number of primary-school pupils in the household (chi(2) for linear trend 6.47, P=0.01). We concluded that in a population with a low prevalence of hepatitis A, adults who live in the same household as primary-school-age children are at increased risk of acquiring the infection during community outbreaks.