Recovery of hepatitis A virus from a water supply responsible for a common source outbreak of hepatitis A

Natural Host-Environmental Media-Human: A New Potential Pathway of COVID-19 Outbreak

Identifying the first infected case (patient zero) is key in tracing the origin of a virus; however, doing so is extremely challenging. Patient zero for coronavirus disease 2019 (COVID-19) is likely to be permanently unknown. Here, we propose a new viral transmission route by focusing on the environmental media containing viruses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or RaTG3-related bat-borne coronavirus (Bat-CoV), which we term the "environmental quasi-host." We reason that the environmental quasi-host is likely to be a key node in helping recognize the origin of SARS-CoV-2; thus, SARS-CoV-2 might be transmitted along the route of natural host-environmental media-human. Reflecting upon viral outbreaks in the history of humanity, we realize that many epidemic events are caused by direct contact between humans and environmental media containing infectious viruses. Indeed, contacts between humans and environmental quasi-hosts are greatly increasing as the space of human activity incrementally overlaps with animals' living spaces, due to the rapid development and population growth of human society. Moreover, viruses can survive for a long time in environmental media. Therefore, we propose a new potential mechanism to trace the origin of the COVID-19 outbreak.

Prevention of Hepatitis A Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices, 2020

HEPATITIS A IS A VACCINE-PREVENTABLE, COMMUNICABLE DISEASE OF THE LIVER CAUSED BY THE HEPATITIS A VIRUS (HAV). THE INFECTION IS TRANSMITTED VIA THE FECAL-ORAL ROUTE, USUALLY FROM DIRECT PERSON-TO-PERSON CONTACT OR CONSUMPTION OF CONTAMINATED FOOD OR WATER. HEPATITIS A IS AN ACUTE, SELF-LIMITED DISEASE THAT DOES NOT RESULT IN CHRONIC INFECTION. HAV ANTIBODIES (IMMUNOGLOBULIN G [IGG] ANTI-HAV) PRODUCED IN RESPONSE TO HAV INFECTION PERSIST FOR LIFE AND PROTECT AGAINST REINFECTION; IGG ANTI-HAV PRODUCED AFTER VACCINATION CONFER LONG-TERM IMMUNITY. THIS REPORT SUPPLANTS AND SUMMARIZES PREVIOUSLY PUBLISHED RECOMMENDATIONS FROM THE ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) REGARDING THE PREVENTION OF HAV INFECTION IN THE UNITED STATES. ACIP RECOMMENDS ROUTINE VACCINATION OF CHILDREN AGED 12-23 MONTHS AND CATCH-UP VACCINATION FOR CHILDREN AND ADOLESCENTS AGED 2-18 YEARS WHO HAVE NOT PREVIOUSLY RECEIVED HEPATITIS A (HEPA) VACCINE AT ANY AGE. ACIP RECOMMENDS HEPA VACCINATION FOR ADULTS AT RISK FOR HAV INFECTION OR SEVERE DISEASE FROM HAV INFECTION AND FOR ADULTS REQUESTING PROTECTION AGAINST HAV WITHOUT ACKNOWLEDGMENT OF A RISK FACTOR. THESE RECOMMENDATIONS ALSO PROVIDE GUIDANCE FOR VACCINATION BEFORE TRAVEL, FOR POSTEXPOSURE PROPHYLAXIS, IN SETTINGS PROVIDING SERVICES TO ADULTS, AND DURING OUTBREAKS.

A Systematic Review of Waterborne Disease Outbreaks Associated with Small Non-Community Drinking Water Systems in Canada and the United States

Background

Reports of outbreaks in Canada and the United States (U.S.) indicate that approximately 50% of all waterborne diseases occur in small non-community drinking water systems (SDWSs). Summarizing these investigations to identify the factors and conditions contributing to outbreaks is needed in order to help prevent future outbreaks.

Objectives

The objectives of this study were to: 1) identify published reports of waterborne disease outbreaks involving SDWSs in Canada and the U.S. since 1970; 2) summarize reported factors contributing to outbreaks, including water system characteristics and events surrounding the outbreaks; and 3) identify terminology used to describe SDWSs in outbreak reports.

Methods

Three electronic databases and grey literature sources were searched for outbreak reports involving SDWSs throughout Canada and the U.S. from 1970 to 2014. Two reviewers independently screened and extracted data related to water system characteristics and outbreak events. The data were analyzed descriptively with ‘outbreak’ as the unit of analysis.

Results

From a total of 1,995 citations, we identified 50 relevant articles reporting 293 unique outbreaks. Failure of an existing water treatment system (22.7%) and lack of water treatment (20.2%) were the leading causes of waterborne outbreaks in SDWSs. A seasonal trend was observed with 51% of outbreaks occurring in summer months (p<0.001). There was large variation in terminology used to describe SDWSs, and a large number of variables were not reported, including water source and whether water treatment was used (missing in 31% and 66% of reports, respectively).

Conclusions

More consistent reporting and descriptions of SDWSs in future outbreak reports are needed to understand the epidemiology of these outbreaks and to inform the development of targeted interventions for SDWSs. Additional monitoring of water systems that are used on a seasonal or infrequent basis would be worthwhile to inform future protection efforts.

Source identification through social networks in an epidemiological investigation of a hepatitis A outbreak at an elementary school in Anhui province, China

In May 2011, the Center for Disease Control and Prevention of a Chinese county found a rapid increase in the number of hepatitis A case notification; these were traced to an outbreak in an elementary school. Twenty-eight cases aged between 7 and 13 years with onset between 7 May and 8 June were serologically confirmed. Network method was conducted to reconstruct an outbreak network and to quantify the relative importance of those involved in the outbreak. A case-control study was used to study the association between the outbreak and putative risk factors. The network analysis suggested this was a disseminated outbreak originating from a 4-year-old boy with propagated spread. Evidence from the case-control study supported consumption of well water as a potential risk factor; however, this was unable to be established through field investigation. Outbreak networks can be used to identify the possible source of infectious disease outbreak, especially when the environmental investigation information is negative or not available.

Estimating acute viral hepatitis infections from nationally reported cases

OBJECTIVES

Because only a fraction of patients with acute viral hepatitis A, B, and C are reported through national surveillance to the Centers for Disease Control and Prevention, we estimated the true numbers.

METHODS

We applied a simple probabilistic model to estimate the fraction of patients with acute hepatitis A, hepatitis B, and hepatitis C who would have been symptomatic, would have sought health care tests, and would have been reported to health officials in 2011.

RESULTS

For hepatitis A, the frequencies of symptoms (85%), care seeking (88%), and reporting (69%) yielded an estimate of 2730 infections (2.0 infections per reported case). For hepatitis B, the frequencies of symptoms (39%), care seeking (88%), and reporting (45%) indicated 18 730 infections (6.5 infections per reported case). For hepatitis C, the frequency of symptoms among injection drug users (13%) and those infected otherwise (48%), proportion seeking care (88%), and percentage reported (53%) indicated 17 100 infections (12.3 infections per reported case).

CONCLUSIONS

These adjustment factors will allow state and local health authorities to estimate acute hepatitis infections locally and plan prevention activities accordingly.

Health of caravan park residents: a pilot cross-sectional study in the East Riding of Yorkshire

Long-stay coastal caravan communities are common in Britain and anecdotal evidence suggests a high level of socio-economic deprivation, and substantial health needs. A pilot cross-sectional study of English caravan communities in Yorkshire found very high rates of poor health and limiting long-term illness compared with regional and national data and exceeding rates explained by demography and deprivation alone. These insights into previously overlooked health inequalities warrant concern and merit further research and intervention to address them. The study also demonstrates the feasibility of our methodology in these hard-to-reach coastal caravan communities.

An outbreak of hepatitis A in recently vaccinated students from ice snacks made from contaminated well water

On 30 May 2006, township S in Sichuan Province, China, reported an outbreak of hepatitis A (HA) in students who had recently received HA vaccine. The concern was raised that the vaccine had caused the outbreak. We attempted to identify the source of infection and mode of transmission. A HA case was defined as onset of jaundice or anorexia since 1 April 2006 with a twofold elevation of alanine aminotransferase (ALT) and anti-HA virus-IgM in a resident of or visitor to the township. Exposures to vaccine and snacks of 90 case-students to those of 107 control-students were compared. Thirty-four per cent of cases ate ice slush compared to 4.7% of controls (OR 4.1), and 51% of cases ate snow cones compared to 17% of controls (OR 8.3). The ice snacks were made with well water. HA virus RNA was detected by reverse transcription-polymerase chain reaction from patients' blood and well water. Untreated well water poses important dangers to the public in areas where piped, potable water is available.

Recovery and sequence analysis of hepatitis a virus from springwater implicated in an outbreak of acute viral hepatitis

An outbreak of acute hepatitis A virus in North Carolina was linked to drinking water from a contaminated shallow spring by phylogenetic analysis of hepatitis A virus (HAV) genomic sequences. Detection of HAV and fecal indicators in the water provided useful and timely information to assist with public health prevention and control measures.

The association between rainfall rate and occurrence of an enterovirus epidemic due to a contaminated well

AIMS

To determine the association between rainfall rate and occurrence of enterovirus infection related to contamination of drinking water.

METHODS AND RESULTS

One fatality case and three cases of severe illness were observed during the enterovirus epidemic in a village in southern Taiwan from 16 September to 3 October 1998. Groundwater samples were collected from the public well in the village after heavy rainfall to test for enterovirus using the reverse transcription-polymerase chain reaction (RT-PCR) assay. The RT-PCR assay detected the enterovirus in the groundwater sample collected on 26 September 1998. The logistic regression model also revealed a statistically significant association between the rainfall rate and the observation of cases of enterovirus infection.

CONCLUSIONS

According to the fitted logistic regression model, the probability of detecting cases of enterovirus infection was greater than 50% at rainfall rates >31 mm h(-1). The higher the rainfall rate, the higher the probability of enterovirus epidemic.

SIGNIFICANCE AND IMPACT OF THE STUDY

Contamination of drinking water by the enterovirus may lead to epidemics that cause deaths and severe illness, and such contamination may be caused by heavy rainfall. The major finding in this study is that the enterovirus could be flushed to groundwater in an unconfined aquifer after a heavy rainfall. This work allows for a warning level so that an action can be taken to minimize future outbreaks and so protect public health.

Published case studies of waterborne disease outbreaks--evidence of a recurrent threat

Residents of affluent nations are remarkably lucky to have high-quality, safe drinking water supplies that most residents of modem cities enjoy, particularly when considered in contrast to the toll of death and misery that unsafe drinking water causes for most of the world's population. Some may presume that drinking-water disease outbreaks are a thing of the past, but complacency can easily arise. A review of drinking water outbreaks in developed countries over the past 3 decades reveals some of the reasons why drinking water outbreaks keep occurring when society clearly has the means to prevent them. Prevention of future outbreaks does not demand perfection, only a commitment to learn from past mistakes and to act on what has been learned.

Comparative evaluation of new TaqMan real-time assays for the detection of hepatitis A virus

Three novel real-time TaqMan RT-PCR assays targeting the 5'-UTR, the viral protease and the viral polymerase regions of the hepatitis A virus (HAV) were developed, evaluated and compared against a new published 5'-UTR TaqMan assay (JN) and a widely used conventional RT-PCR assay (HAVc). All conventional RT-PCR (HAV, SH-Prot and SH-Poly systems) and TaqMan (SH-Prot, SH-Poly, JN and SH-5U systems) assays evaluated were consistent for the detection of the three different HAV strains (HM-175, HAS-15 and LSH/S) used and reproducible for both RNA duplicates with the exception of two reproducibility discrepancies observed with both 5'-UTR real-time systems (JN and SH-5U). Limits of detection for conventional HAV, SH-Prot and SH-Poly RT-PCR systems were found to be equivalent when tested with serially diluted suspensions of the HM-175 strain. Although the four real-time RT-PCR TaqMan assays evaluated herein produced similar and consistent quantification data down to the level of one genomic equivalent copy with their respectively cloned amplicons, significant and important differences were observed for the detection of HAV genomic RNA. Results showed that the new real-time TaqMan SH-Poly and SH-Prot primer and probe systems were more consistent and sensitive by 5 logs as compared to both 5'-UTR designs (JN and SH-5U) used for the detection of HAV genomic RNA as well as for the detection in cell culture by cytopathic effect. Considering their higher analytical sensitivity, the proposed SH-Poly and SH-Prot amplification systems could therefore represent valuable tools for the detection of HAV in clinical, environmental and food samples.

Detection and characterization of hepatitis A virus in water samples in Thailand

AIMS

Outbreaks of hepatitis A in Thailand have been reported continuely and associated with water supply. However, the genetic analysis of hepatitis A virus (HAV) in water is limited. This study described the application of virus concentration method and reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) to detect HAV RNA and analyse the genetic sequence of the virus in environmental water samples.

METHODS AND RESULTS

The HAV from water samples was concentrated by using a developed virus concentration method (adsorption-elution and subsequent speedVac reconcentration) and the viral RNA was detected by RT-nested PCR followed by sequencing of the amplified DNA products. Detection limit of HAV determined by the RT-nested PCR was 1.29 radioimmunofocus assay (RIFA) units ml(-1). The DNA band appeared at 183 basepairs. No cross-reactivity was observed in the presence of other enteric viruses (poliovirus and rotavirus). A total of 180 water samples were collected, concentrated, and detected for HAV. The HAV was found in 6/40 (15%) of water samples collected from a swamp and 3/30 (10%) collected from a canal. Ten river samples and 100 tap water samples stored in containers for drinking and domestic uses were negative for HAV. In sequence analysis of the DNA products and alignment with the HAV sequence deposited in the GenBank, six water samples showed the nucleotide sequence associated with HAV. The 120 nucleotides in the N-terminal VP1 region obtained from two swamp samples showed 95 and 96.7% identity to HAV genotype IA. In nearly all water samples where HAV was present bacterial indicators (faecal coliforms and Escherichia coli) were found for faecal contamination.

CONCLUSIONS

A coupled virus concentration method and RT-nested PCR was successfully applied to examine HAV in water samples collected from various sources. DNA sequencing of nested PCR products showed the genotype IA associated with HAV that is predominate in Thailand.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research is the first study of genetic sequence of HAV in water samples in Thailand. The presence of naturally occurring HAV might pose a potential health risk for people.

Diagnosis of hepatitis a virus infection: a molecular approach

Current serologic tests provide the foundation for diagnosis of hepatitis A and hepatitis A virus (HAV) infection. Recent advances in methods to identify and characterize nucleic acid markers of viral infections have provided the foundation for the field of molecular epidemiology and increased our knowledge of the molecular biology and epidemiology of HAV. Although HAV is primarily shed in feces, there is a strong viremic phase during infection which has allowed easy access to virus isolates and the use of molecular markers to determine their genetic relatedness. Molecular epidemiologic studies have provided new information on the types and extent of HAV infection and transmission in the United States. In addition, these new diagnostic methods have provided tools for the rapid detection of food-borne HAV transmission and identification of the potential source of the food contamination.

Diagnosis of hepatitis a virus infection: a molecular approach

Current serologic tests provide the foundation for diagnosis of hepatitis A and hepatitis A virus (HAV) infection. Recent advances in methods to identify and characterize nucleic acid markers of viral infections have provided the foundation for the field of molecular epidemiology and increased our knowledge of the molecular biology and epidemiology of HAV. Although HAV is primarily shed in feces, there is a strong viremic phase during infection which has allowed easy access to virus isolates and the use of molecular markers to determine their genetic relatedness. Molecular epidemiologic studies have provided new information on the types and extent of HAV infection and transmission in the United States. In addition, these new diagnostic methods have provided tools for the rapid detection of food-borne HAV transmission and identification of the potential source of the food contamination.

Genetic variability of hepatitis A virus isolates in Rio de Janeiro: implications for the vaccination of school children

The epidemiology of hepatitis A virus (HAV) infection is shifting from high to intermediate endemicity in Brazil, resulting in increased numbers of susceptible individuals and a greater potential for the emergence of outbreaks. Universal vaccination against HAV has been recommended for children, but updated sero-epidemiological data are necessary to analyze the level of natural immunity and to identify candidates for preventive measures. In addition, more molecular studies are necessary to characterize the genotypes involved in HAV infections and outbreaks. Sera from 299 school children (5-15 years old) and 25 school staff members, collected during an outbreak of HAV at a rural public school in June 2000, were tested for IgM and total anti-HAV antibodies (ELISA). Viral RNA was amplified by RT-PCR from anti-HAV IgM-positive sera and from 19 fecal samples. Direct nucleotide sequencing of the VP1/2A region was carried out on 18 PCR-positive samples. Acute HAV infection was detected by anti-HAV IgM in 93/299 children and in 3/25 adult staff members. The prevalence of total anti-HAV antibodies in IgM-negative children under 5 years of age was only 10.5%. HAV-RNA was detected in 46% IgM-positive serum samples and in 16% stool samples. Sequence analysis showed that half the isolates belonged to subgenotype IA and the other half to IB. On the basis of these data, mass vaccination against HAV is recommended without prevaccination screening, especially for children before they enter school, since nearly 90% of the children under 5 years were susceptible. Molecular characterization indicated the endemic circulation of specific HAV strains belonging to subgenotypes IA and IB.

Hepatitis A Transmitted by Food

Hepatitis A is caused by hepatitis A virus (HAV). Transmission occurs by the fecal-oral route, either by direct contact with an HAV-infected person or by ingestion of HAV-contaminated food or water. Foodborne or waterborne hepatitis A outbreaks are relatively uncommon in the United States. However, food handlers with hepatitis A are frequently identified, and evaluation of the need for immunoprophylaxis and implementation of control measures are a considerable burden on public health resources. In addition, HAV-contaminated food may be the source of hepatitis A for an unknown proportion of persons whose source of infection is not identified.

Incidence of enteric viruses in groundwater from household wells in Wisconsin

Recent studies on the contamination of groundwater with human enteric viruses have focused on public water systems, whereas little is known about the occurrence of viruses in private household wells. The objective of the present study was to estimate the incidence of viruses in Wisconsin household wells located near septage land application sites or in rural subdivisions served by septic systems. Fifty wells in seven hydrogeologic districts were sampled four times over a year, once each season. Reverse transcriptase PCR (RT-PCR), followed by Southern hybridization, was used to detect enteroviruses, rotavirus, hepatitis A virus (HAV), and Norwalk-like viruses (NLVs). In addition, cell culture was used to detect culturable enteroviruses. Companion water samples were collected for total coliforms, Escherichia coli, fecal enterococci, F-specific RNA coliphages, nitrate, and chloride analyses. Among the 50 wells, four (8%) were positive for viruses by RT-PCR. Three wells were positive for HAV, and the fourth well was positive for both rotavirus and NLV in one sample and an enterovirus in another sample. Contamination was transient, since none of the wells was virus positive for two sequential samples. Culturable enteroviruses were not detected in any of the wells. Water quality indicators were not statistically associated with virus occurrence, although some concordance was noted for chloride. The present study is the first in the United States to systematically monitor private household wells for virus contamination and, combined with data for public wells, provides further insight on the extent of groundwater contamination with human enteric viruses.

Hepatitis A: old and new

The hepatitis A virus (HAV), a picornavirus, is a common cause of hepatitis worldwide. Spread of infection is generally person to person or by oral intake after fecal contamination of skin or mucous membranes; less commonly, there is fecal contamination of food or water. Hepatitis A is endemic in developing countries, and most residents are exposed in childhood. In contrast, the adult population in developed countries demonstrates falling rates of exposure with improvements in hygiene and sanitation. The export of food that cannot be sterilized, from countries of high endemicity to areas with low rates of infection, is a potentially important source of infection. After ingestion and uptake from the gastrointestinal tract, the virus replicates in the liver and is excreted into the bile. Cellular immune responses to the virus lead to destruction of infected hepatocytes with consequent development of symptoms and signs of disease. Humoral immune responses are the basis for diagnostic serologic assays. Acute HAV infection is clinically indistinguishable from other causes of acute viral hepatitis. In young children the disease is often asymptomatic, whereas in older children and adults there may be a range of clinical manifestations from mild, anicteric infection to fulminant hepatic failure. Clinical variants include prolonged, relapsing, and cholestatic forms. Management of the acute illness is supportive, and complete recovery without sequelae is the usual outcome. Research efforts during World War II led to the development of passive immunoprophylaxis. Pooled immune serum globulin is efficacious in the prevention and attenuation of disease in exposed individuals. More recently, active immunoprophylaxis by vaccination has been accomplished. Future eradication of this disease can now be contemplated.

Detection of hepatitis A viral RNA in sera of patients with acute hepatitis A

BACKGROUND AND AIMS

The Detection of hepatitis A virus (HAV) is important for diagnosis and epidemiological studies of hepatitis A. The polymerase chain reaction (PCR) technique is a sensitive test to detect HAV-RNA in specimens. The aims of the present study were to clarify the detection rate of serum HAV-RNA by PCR and the natural history of HAV viraemia, and to determine the correlation between viraemia and the clinical characteristics in patients with acute hepatitis A.

METHODS

Hepatitis A virus RNA was tested in 74 serum samples which were serially collected from 27 patients with acute hepatitis A. A nested reverse transcription (RT)-PCR for HAV-RNA was performed with primer sets located at the VP1 region of the HAV genome and the PCR products were electrophoresed on a 1.5% agarose gel.

RESULTS

Hepatitis A virus RNA was found in 18 of 27 (67%) patients with hepatitis A. There were no significant differences between groups positive and negative for HAV-RNA in clinical and laboratory data, except the time interval between clinical onset and initial serum sampling for RT-PCR (10 +/- 6 vs 19 +/- 14 days) and the alanine aminotransferase (ALT) level at initial serum sampling for RT-PCR (1436 +/- 1416 vs 518 +/- 432 IU/L). The mean duration of HAV viraemia was 30 +/- 19 days (range, 5-59 days). The duration of HAV viraemia and duration of abnormal ALT levels from clinical onset were positively correlated (r = 0.685, P = 0.007).

CONCLUSION

In conclusion, HAV-RNA RT-PCR is a useful tool to detect HAV viraemia and to study the molecular epidemiology of HAV infection.

Occurrence of pathogenic microorganisms in the Saint Lawrence River (Canada) and comparison of health risks for populations using it as their source of drinking water

A 300-km portion of the Saint Lawrence hydrological basin in the province of Québec (Canada) and 45 water treatment plants were studied. River water used by drinking water treatment plants was analyzed (6-L sample volumes) to determine the level of occurrence of bacterial indicators (total coliforms, fecal coliforms, and Clostridium perfringens) and pathogens (Giardia lamblia, Cryptosporidium, human enteric viruses). Pathogens and bacterial indicators were found at all sites at a wide range of values. Logistic regression analysis revealed significant correlations between the bacterial indicators and the pathogens. Physicochemical and treatment practices data were collected from most water treatment plants and used to estimate the level of removal of pathogens achieved under cold (0°C-4°C) and warm (20°C-25°C) water temperature conditions. The calculated removal values were then used to estimate the annual risk of Giardia infection using mathematical models and to compare the sites. The estimated range of probability of infection ranged from 0.75 to less than 0.0001 for the populations exposed. Given the numerous assumptions made, the model probably overestimated the annual risk, but it provided comparative data of the efficacy of the water treatment plants and thereby contributes to the protection of public health.Key words: public health, drinking water, health risk, pathogen occurrence.

Evaluation of occupational transmission of hepatitis A virus among wastewater workers

To provide information concerning potential occupational transmission of hepatitis A virus (HAV) among wastewater workers in a large city in the United States, a cross-sectional survey was performed using a saliva test to detect antibodies to HAV (anti-HAV). Fifty-nine (20%) of 302 participants tested positive for anti-HAV. After controlling for the confounding effects of age and race, wastewater work was not significantly associated with an increase in the prevalence of anti-HAV (prevalence ratio = 1.3; 95% confidence interval 0.7 to 2.4). Additionally, when examining only the wastewater workers, no statistically significant occupational risk factors for anti-HAV were identified. The results of this survey are consistent with the position of the Centers for Disease Control and Prevention regarding groups at risk for HAV infection.

Detection of hepatitis A virus RNA in oyster meat

Detection of low concentrations of viruses in shellfish is possible with nucleic acid amplification by PCR. Hepatitis A virus (HAV) has been detected in oyster meat by reverse transcription-PCR (RT-PCR). We developed a method to identify HAV RNA by RT-PCR of total RNA extracted from oyster meat contaminated by adsorption, bioaccumulation, or injection. With dot blot hybridization detection of amplicons from the RT-PCR, rapid screening of a large number of samples is feasible. As few as 8 PFU of HAV/g of oyster meat can be detected.

An outbreak of Escherichia coli O157 and campylobacteriosis associated with contamination of a drinking water supply

Stream water into which treated sewage discharged contaminated the public water supply of a Fife village with a population of about 1100. Of 765 residents and workers who reported illness 711 had gastrointestinal symptoms and 633 were defined as cases. Mains water analysis revealed high faecal coliform counts. An outbreak of Campylobacter and E coli 0157 infection was bacteriologically confirmed in eight and six people respectively. Two of the latter developed haemolytic uraemic syndrome. All affected individuals made full recoveries. Human normal immunoglobulin was offered to those aged between six months and 40 years of age and 618 individuals were immunised. Salivary tests four months after the incident confirmed that no Hepatitis A outbreak had occurred. In a follow-up questionnaire residents generally expressed happiness with the medical response to the incident although many reported that they still had worries. The two major medical issues which emerged from this outbreak were the importance of effective communications and the appropriateness of offering post-exposure human normal immunoglobulin.

New developments in hepatitis A control

An inactivated vaccine for hepatitis A was recently licensed in Canada. This is the first important development in control of the disease in 50 years. This article presents new information about the vaccine and about the groups who might benefit from it. It also provides a review of the clinical and epidemiological aspects of hepatitis A.

Hepatitis A virus identification in an outbreak by enzymatic amplification

From April 28th to May 22nd, 1987, the Medical Authority identified 13 cases (6 symptomatic cases) of hepatitis A (HA) in a school and in a college of Rome. The principal risk factor was determined to be "full-time presence at the State school and boarders at the college". The distribution of HA cases suggested a person to person contact; anti-hepatitis A virus IgM were identified in 12 out of 13 cases with high levels of transaminases. During the disease epidemic, water samples were taken from the well of the college for bacteriological and virological analyses. The water was classified as undrinkable due to the presence of 16 total coliforms/100 ml and 35 total bacteria count at 36 degrees C. Fecal coliforms, fecal streptococci and sulfite reducing clostridia were absent. Two water samples of 100 liters were collected and concentrated by adsorption-elution method on electropositive membranes or by ultrafiltration using a Millipore apparatus. Infectious Hepatitis A virus was only isolated from samples concentrated by adsorption-elution method on electropositive membranes using tissue culture methods and subsequently HA virus was identified by other traditional methods (Elisa and immunofluorescence). In contrast, PCR test performed on the concentrated samples, was positive only for the ultraconcentrated sample. The positivity of the PCR test confirmed the presence of the Hepatitis A virus in the well water.

Hepatitis A epidemics from utility sewage in Ocoee, Florida

The 1988-1989 hepatitis A epidemic in the Palms section of Ocoee, Florida, followed sewage overflows and involved 39 cases and a fetal death. Of the 18 index cases (i.e., the first hepatitis illness in a household), each had a history of contact with sewage-contaminated stormwater and no other known contact with the infection. Illnesses varied from mild to severe; 20 people reported that diarrhea, abdominal pain, varying degrees of ascites, and other symptoms continued for 2 y after the initial illness. Health injuries up to 20 y of lost life, measured by CEA-Clinical Epidemiological AnalysisSM, were found. Public records of rainfall and sewage flows provide evidence of massive stormwater entry into the utility system, which periodically appears to have flushed sewage from the utility lift station into residential areas.

Worldwide epidemiology of hepatitis A virus infection

Patterns of hepatitis A virus (HAV) infection and clinical disease differ worldwide, and correlate with socioeconomic conditions (and hygienic and sanitary conditions) of each geographic area. In least developed countries with very poor sanitary and hygienic conditions, HAV spreads readily, and most persons are infected as young children. Because most persons become infected at an age when HAV infection is often asymptomatic, reported disease rates in these areas are low and outbreaks of disease are rare. In developing countries and some regions of developed countries, sanitary conditions are variable, and transmission can predominate in children, adolescents or adults, depending on the geographic region. Paradoxically, since HAV transmission occurs in these areas in older age groups compared with least developed countries where HAV transmission is highly endemic, reported rates of hepatitis A can be higher. In developed countries, sanitation and hygienic conditions are good, and infection rates in children are generally low. Communitywide epidemics can contribute significantly to the burden of disease, as can occasional day care center and common-source outbreaks. In some areas, disease tends to be among specific risk groups, such as travellers to hepatitis A endemic areas, and intravenous drug users among whom hygienic practices may be poor. As countries develop economically with improvement of sanitary conditions, overall endemicity of HAV infection decreases, and disease patterns may change. As the endemicity of HAV transmission decreases, the reported rate of clinical hepatitis A can increase, due to the shift in the average age of infection to an age when clinical illness is more frequent.

A multistate outbreak of hepatitis A caused by the consumption of raw oysters

BACKGROUND

In August 1988 we investigated a multistate outbreak of hepatitis A caused by Panama City, Florida, raw oysters.

METHODS

Cases of hepatitis A (HA) with onset in July-August 1988 were identified among persons who ate seafoods harvested in the coastal waters of Panama City, Florida. We conducted a case-control study, using eating companions of case-patients, and calculated attack rate (AR) per 1000 dozen raw oysters served. Enzyme immunoassay (EIA) and a polymerase chain reaction (PCR) technique were performed on samples of raw shellfish obtained from Panama City coastal waters.

RESULTS

Sixty-one case-patients were identified in five states: Alabama (23), Georgia (18), Florida (18), Tennessee (1), and Hawaii (1). We found an increased risk of HA for raw oyster eaters (odds ratio = 24.0; 95% confidence interval = 5.4-215.0; P less than .001). The AR of HA in seafood establishments was 1.9/1000 dozen raw oysters served. The EIA and PCR revealed HA virus antigen and nucleic acid in oysters from both unapproved and approved oyster beds, in confiscated illegally harvested oysters, and in scallops from an approved area.

CONCLUSIONS

The monitoring of coastal waters and the enforcement of shellfish harvesting regulations were not adequate to protect raw oyster consumers. More emphasis should be placed on increasing public awareness of health hazards associated with eating raw shellfish.