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Objective.To identify patient-care practices related to an increased prevalence of hepatitis C virus (HCV) infection among chronic hemodialysis patients.Design.Survey.Setting.Chronic hemodialysis facilities in the United States.Participants.Equal-probability 2-stage cluster sampling was used to select 87 facilities from all Medicare-approved providers treating 30–150 patients; 53 facilities and 2,933 of 3,680 eligible patients agreed to participate.Methods.Patients were tested for HCV antibody and HCV RNA. Data on patient-care practices were collected using direct observation.Results.The overall prevalence of HCV infection was 9.9% (95% confidence interval [CI], 8.2%–11.6%); only 2 of 294 HCV-positive patients were detected solely by HCV RNA testing. After adjusting for non-dialysis-related HCV risk factors, patient-care practices independently associated with a higher prevalence of HCV infection included reusing priming receptacles without disinfection (odds ratio [OR], 2.3 [95% CI, 1.4–3.9]), handling blood specimens adjacent to medications and clean supplies (OR, 2.2 [95% CI, 1.3–3.6]), and using mobile carts to deliver injectable medications (OR, 1.7 [95% CI, 1.0–2.8]). Independently related facility covariates were at least 10% patient HCV infection prevalence (OR, 3.0 [95% CI, 1.8–5.2]), patient-to-staff ratio of at least 7: 1 (OR, 2.4 [95% CI, 1.4–4.1]), and treatment duration of at least 2 years (OR, 2.4 [95% CI, 1.3–4.4]).Conclusions.This study provides the first epidemiologic evidence of associations between specific patient-care practices and higher HCV infection prevalence among hemodialysis patients. Staff should review practices to ensure that hemodialysis-specific infection control practices are being implemented, especially handling clean and contaminated items in separate areas, reusing items only if disinfected, and prohibiting mobile medication and clean supply carts within treatment areas.

We used molecular epidemiologic techniques to document patient-to-patient transmission of hepatitis B virus (HBV) between 2 outpatient oral surgery patients operated on 161 min apart. Serological testing of 25 (93%) of 27 patients operated on after the source patient revealed that 19 (76%) of 25 were previously immune to HBV; no additional cases were identified. We found no deficiencies in infection control practices. Transmission may have been limited by the high prevalence (64%) of patients vaccinated against HBV. To our knowledge, this is the first documented case of patient-to-patient transmission of a bloodborne pathogen in a dental setting in the United States.

The goal of the present study was to assess risk factors for perinatal hepatitis C virus (HCV) transmission and the natural history of infection among HCV-infected infants.In a cohort study, 244 infants born to HCV-positive mothers were followed from birth until ageor =12 months. Maternal serum was collected at enrollment and delivery; infant serum was collected at birth and at 8 well-child visits. Testing included detection of antibody to HCV, detection of HCV RNA (qualitative and quantitative), and genotyping. HCV-infected infants were followed annually until age 5 years.Overall, 9 of 190 (4.7% [95% confidence interval (CI), 2.3%-9.1%]) infants born to mothers who were HCV RNA positive at delivery became infected, compared with 0 of 54 infants born to HCV RNA-negative mothers (P=.10). Among HCV RNA-positive mothers, the rate of transmission was 3.8% (95% CI, 1.7%-8.1%) from the 182 who were human immunodeficiency virus (HIV) negative, compared with 25.0% (95% CI, 4.5%-64.4%) from the 8 who were HIV positive (P.05). Three infected infants resolved their infection (i.e., became HCV RNA negative). In multivariate analysis restricted to HCV RNA-positive mothers, membrane ruptureor =6 h (odds ratio [OR], 9.3 [95% CI, 1.5-179.7]) and internal fetal monitoring (OR, 6.7 [95% CI, 1.1-35.9]) were associated with transmission of HCV to infants.If duration of membrane rupture and internal fetal monitoring are confirmed to be associated with transmission, interventions may be possible to decrease the risk of transmission.

Objectives. We sought to determine hepatitis B virus (HBV) infection prevalence, associated exposures, and incidence among male inmates at a state correctional facility. Methods. A cross-sectional serological survey was conducted in June 2000, and susceptible inmates were retested in June 2001. Results. At baseline, 230 inmates (20.5%; 95% confidence interval [CI]=18.2%, 22.9%) exhibited evidence of HBV infection, including 11 acute and 11 chronic infections. Inmates with HBV infection were more likely than susceptible inmates to have injected drugs (38.8% vs 18.0%; adjusted prevalence odds ratio [OR]=3.0; 95% CI=1.9, 4.9), to have had more than 25 female sex partners (27.7% vs 17.5%; adjusted prevalence OR=2.0; 95% CI=1.4, 3.0), and to have been incarcerated for more than 14 years (38.4% vs 17.6%; adjusted prevalence OR=1.7; 95% CI=1.1, 2.6). One year later, 18 (3.6%) showed evidence of new HBV infection. Among 19 individuals with infections, molecular analysis identified 2 clusters involving 10 inmates, each with a unique HBV sequence. Conclusions. We documented ongoing HBV transmission at a state correctional facility. Similar transmission may occur at other US correctional facilities and could be prevented by vaccination of inmates.

Objectives:To determine whether hepatitis B virus (HBV) transmission occurred among patients visiting a physician's office and to evaluate potential transmission mechanisms.Design:Serologic survey, retrospective cohort study, and observation of infection control practices.Setting:Private medical office.Patients:Those visiting the office between March 1 and December 26, 2001.Results:We identified 38 patients with acute HBV infection occurring between February 2000 and February 2002. The cohort study, limited to the 10 months before outbreak detection, included 91 patients with serologic test results and available charts representing 18 case-patients and 73 susceptible patients. Overall, 67 patients (74%) received at least one injection during the observation period. Case-patients received a median of 14 injections (range, 2-25) versus 2 injections (range, 0-17) for susceptible patients (P < .001). Acute infections occurred among 18 (27%) of 67 who received at least one injection versus none of 24 who received no injections (RR, 13.6; CI95, 2.4-undefined). Risk of infection increased 5.2-fold (CI95, 0.6-47.3) for those with 3 to 6 injections and 20.0-fold (CI95, 2.8-143.5) for those with more than 6 injections. Typically, injections consisted of doses of atropine, dexamethasone, vitamin B12, or a combination of these mixed in one syringe. HBV DNA genetic sequences of 24 patients with acute infection and 4 patients with chronic infection were identical in the 1,500-bp region examined. Medical staff were seronegative for HBV infection markers. The same surface was used for storing multidose vials, preparing injections, and dismantling used injection equipment.Conclusion:Administration of unnecessary injections combined with failure to separate clean from contaminated areas and follow safe injection practices likely resulted in patient-to-patient HBV transmission in a private physician's office.

Illicit drug use (IDU) is an important risk factor for hepatitis A, but implementing vaccination programs among drug users is difficult. During January 2001–July 2002, 403 hepatitis A cases were reported in Polk County, Florida; 48% were drug users and of these, 80% were recently in jail. To assess the county jail as a potential vaccination venue, we interviewed 280 inmates and conducted a serologic survey during July–August 2002. Of these, 227 (81%) reported a past IDU history. Previous HAV infection was found in 33%. In communities with illicit drug users at risk for hepatitis A and who are frequently jailed, vaccination programs in jails could be an important component of a community-based strategy to control hepatitis A outbreaks among illicit drug users.

Death related to acute hepatitis B occurs in approximately 1% of patients. We investigated an outbreak of hepatitis B virus (HBV) infections among injection drug users (IDUs) resulting in several deaths. We conducted a case-control study of fulminant (case patients) and nonfulminant (control patients) HBV infections. We directly sequenced the entire HBV genome from fulminant and nonfulminant cases. From October 1998 to July 2000, 21 acute HBV infections, including 10 fulminant hepatitis B cases, were identified. The median age was 30 (range, 18-49) years, 12 (57%) were female, 20 (95%) were American Indians, and 20 (95%) reported injecting illicit drugs. All patients with fulminant hepatitis B died (case-fatality rate = 47.6%). Case patients (n = 5) and control patients (n = 9) were similar with respect to age, sex, race, and hepatitis C virus serostatus. All case patients used acetaminophen during their illness compared with 44% of control patients (P = .08). Compared with control patients, case patients lost more weight in the 6 months before illness (P = .04); during their illness, they used more alcohol (P = .03) and methamphetamine (P = .04). All 9 isolates sequenced were genotype D, shared 99.7% homology, and included mutations previously described in association with fulminant hepatitis B. In conclusion, a high prevalence of exposure to factors potentiating hepatic damage with acute hepatitis B contributed to the outbreak's high mortality rate; mutations present in the outbreak strain might also have been a factor. Improved vaccination coverage among IDUs has the potential to prevent similar outbreaks in the future.

Objective:To identify the source of an outbreak of acute hepatitis C virus (HCV) infection among 3 patients occurring within 8 weeks of hospitalization in the same ward of a Florida hospital during November 1998.Design:A retrospective cohort study was conducted among 41 patients hospitalized between November 11 and 19, 1998. Patients' blood was tested for antibodies to HCV, and HCV RNA-positive samples were genotyped and sequenced.Results:Of the 41 patients, 24 (59%) participated in the study. HCV genotype 1b infections were found in 5 patients. Three of 4 patients who received saline flushes from a multidose saline vial on November 16 had acute HCV infection, whereas none of the 9 patients who did not receive saline flushes had HCV infection (P= .01). No other significant exposures were identified. The HCV sequence was available for 1 case of acute HCV and differed by a single nucleotide (0.3%) from that of the indeterminate case.Conclusion:This outbreak of HCV probably occurred when a multidose saline vial was contaminated with blood from an HCV-infected patient. Hospitals should emphasize adherence to standard procedures to prevent blood-borne infections. In addition, the use of single-dose vials or prefilled saline syringes might further reduce the risk for nosocomial transmission of blood-borne pathogens.

Variants in the amino acid composition of the primary antibody-binding site of hepatitis B surface antigen (HBsAg) have been identified in a number of populations with chronic hepatitis B virus (HBV) infection. Direct sequencing of amplified or cloned PCR products, solid phase detection of sequence-specific PCR products (SP-PCR), and limiting dilution cloning PCR (LDC-PCR) were compared to determine their sensitivity in detecting differing concentrations of HBsAg variants. LDC-PCR had the greatest sensitivity and could detect HBsAg variants at a concentration of 0.1% of the total viral population. HBsAg variants were detected in 51% of infants with chronic HBV infection acquired after postexposure prophylaxis, and more than half of the variants were detected only by the most sensitive methods.

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.

The duration of viremia and time course for development of IgM antibodies were determined prospectively in natural and experimental hepatitis A virus (HAV) infection. Serial serum samples from HAV-infected men (n=13) and experimentally infected chimpanzees (n=5) were examined by nested reverse-transcriptase polymerase chain reaction analysis to detect HAV RNA and by ELISA to detect IgM antibodies to HAV. Among infected humans, HAV RNA was detected an average of 17 days before the alanine aminotransferase peak, and viremia persisted for an average of 79 days after the liver enzyme peak. The average duration of viremia was 95 days (range, 36-391 days). Results were similar in chimpanzees. In addition, HAV RNA was detected in serum of humans and chimpanzees several days before IgM antibodies to HAV were detected. These results indicate that adults with HAV infection are viremic for as long as 30 days before the onset of symptoms and that the duration of viremia may be longer than previously described.

In 1993-94, a community-wide outbreak of hepatitis A occurred in Stanislaus County, California. Stool specimens collected from a sample of 33 case patients were used to evaluate the duration of hepatitis A virus (HAV) excretion and the genetic relatedness of HAV isolates. Twenty-four percent of the patients had a stool sample positive for HAV antigen by enzyme immunoassay, whereas 91% had at least one stool positive for HAV RNA by RT-PCR amplification. Children were found to excrete low levels of HAV RNA for up to 10 weeks after the onset of symptoms. Analysis of the HAV VP1 amino terminus and VP1/P2A regions showed that a limited number of HAV isolates circulated during the epidemic and the majority of the cases were infected with the same strain.

Because many persons with chronic hepatitis C virus (HCV) infection are asymptomatic, population-based serologic studies are needed to estimate the prevalence of the infection and to develop and evaluate prevention efforts.We performed tests for antibody to HCV (anti-HCV) on serum samples from 21,241 persons six years old or older who participated in the third National Health and Nutrition Examination Survey, conducted during 1988 through 1994. We determined the prevalence of HCV RNA by means of nucleic acid amplification and the genotype by means of sequencing.The overall prevalence of anti-HCV was 1.8 percent, corresponding to an estimated 3.9 million persons nationwide (95 percent confidence interval, 3.1 million to 4.8 million) with HCV infection. Sixty-five percent of the persons with HCV infection were 30 to 49 years old. Seventy-four percent were positive for HCV RNA, indicating that an estimated 2.7 million persons in the United States (95 percent confidence interval, 2.4 million to 3.0 million) were chronically infected, of whom 73.7 percent were infected with genotype 1 (56.7 percent with genotype 1a, and 17.0 percent with genotype 1b). Among subjects 17 to 59 years of age, the strongest factors independently associated with HCV infection were illegal drug use and high-risk sexual behavior. Other factors independently associated with infection included poverty, having had 12 or fewer years of education, and having been divorced or separated. Neither sex nor racial-ethnic group was independently associated with HCV infection.In the United States, about 2.7 million persons are chronically infected with HCV. People who use illegal drugs or engage in high-risk sexual behavior account for most persons with HCV infection.

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) ...

An outbreak of hepatitis A in a rural river-island community was found to be associated with consumption of contaminated well water. Specimens from case-patients, the implicated well, and a cesspool suspected to be the source of contamination were all positive for hepatitis A virus (HAV) RNA by immunocapture reverse-transcription polymerase chain reaction. All isolates were identical over about 400 bases from two capsid-encoding regions of the genome, identifying the chain of transmission. Other wells up to 60 m from the cesspool also contained HAV RNA. In addition, HAV RNA was detected in the contamination source well 6 months after the initial contamination, when fecal coliform bacteria were no longer present. These findings demonstrate the utility of viral detection techniques to evaluate contaminated ground water.

A pairwise comparison of the nucleic acid sequence of 168 bases from 152 wild-type or unique cell culture-adapted strains of hepatitis A virus (HAV) revealed that HAV strains can be differentiated genetically into seven unique genotypes (I to VII). In general, the nucleotide sequence of viruses in different genotypes differs at 15 to 25% of positions within this segment of the genome. Viruses from four of the genotypes (I, II, III and VII) were recovered from cases of hepatitis A in humans, whereas viruses from the other three genotypes (IV, V and VI) were isolated only from simian species developing a hepatitis A-like illness during captivity. Among non-epidemiologically related human HAV strains, 81 were characterized as genotype I, and 19 as genotype III. Within each of these major genotypes, there were two distinct groups (subgenotypes), which differed in sequence at approximately 7.5% of base positions. Each genotype and subgenotype has a characteristic amino acid sequence in this region of the polyprotein, with the most divergent genotypes differing at 10 of 56 residues. Strains recovered from some geographical regions belonged to a common (endemic) genotype, whereas strains from other regions belonged to several, probably imported, genotypes. Thus, HAV strains recovered in North America were for the most part closely related at the nucleotide sequence level, whereas in other regions, such as Japan and Western Europe, HAV strains were derived from multiple genotypes or sub-genotypes. These data indicate that patterns of endemic transmission can be differentiated from situations in which infections are imported due to travel.

Hepatitis A virus (HAV) isolates from different parts of the world are a single serotype. However, genetic analysis of the VP1 genome region of published HAV sequences suggested that distinct genotypes of HAV could be defined based upon the geographic source of the original isolates. To circumvent the process of cell culture adaptation or animal passage, a 247-bp segment within the VP1 genome region of wild-type HAV was amplified by reverse transcription followed by polymerase chain reaction amplification in the presence of negative- and positive-sense primers. From the sequences obtained from 22 epidemiologically distinct HAV isolates, three genetic groups of HAV could be delineated. Two of the groups differed by 10%, while the third group differed from other isolates by approximately 20%. These investigations indicate that HAV isolates from different parts of the world can be differentiated genetically, which will facilitate studies of epidemiologic transmission.

An approach for determination of hepatitis C virus (HCV) quasispecies by end-point limiting-dilution real-time PCR (EPLD-PCR) is described. It involves isolation of individual coexisting sequence variants of the hypervariable region 1 (HVR1) of the HCV genome from serum specimens using a limiting-dilution protocol. EPLD-PCR applied to an HCV outbreak study provided insights into the epidemiological relationships between incident and chronic cases. When applied to samples from a longitudinal study of infected patients, HVR1 sequences from each sampling time-point were observed to group as distinct phylogenetic clusters. Melting peak analysis conducted on EPLD-PCR products generated from these patients could be used for evaluation of HVR1 sequence heterogeneity without recourse to clonal sequencing. Further, to better understand the mechanism of single-molecule PCR, experiments were conducted under optimal and suboptimal annealing temperatures. Under all temperature conditions tested, HVR1 variants from the major phylogenetic clusters of quasispecies could be amplified, revealing that successful HVR1 quasispecies analysis is not contingent to dilution of starting cDNA preparations to a single-molecule state. It was found that EPLD-PCR conducted at suboptimal annealing temperatures generated distributions of unique-sequence variants slightly different from the distribution obtained by PCR conducted at the optimal temperature. Hence, EPLD-PCR conditions can be manipulated to access different subpopulations of HCV HVR1 quasispecies, thus, improving the range of the quasispecies detection. Although EPLD-PCR conducted at different conditions detect slightly different quasispecies populations, as was shown in this study, the resulted samples of quasispecies are completely suitable for molecular epidemiological investigation in different clinical and epidemiological settings.

Hepatitis A vaccine administered to persons after exposure to the hepatitis A virus has not been compared directly with immune globulin, which is known to be highly effective in preventing hepatitis A when given within 2 weeks after exposure to the virus.We randomly assigned household and day-care contacts, 2 to 40 years of age, in Almaty, Kazakhstan, to receive one standard age-appropriate dose of hepatitis A vaccine or immune globulin within 14 days after exposure to patients with hepatitis A. Instances of laboratory-confirmed, symptomatic hepatitis A infection occurring between 15 and 56 days after exposure were then assessed during active follow-up of all susceptible contacts.Of 4524 contacts who underwent randomization, 1414 (31%) were susceptible to hepatitis A virus and 1090 were eligible for the per-protocol analysis. Among these contacts, 568 received hepatitis A vaccine and 522 received immune globulin. Most contacts were children (average age, 12 years), and most received prophylaxis during the second week after exposure (average interval after exposure, 10 days). The baseline characteristics of the contacts were similar in the two groups. Symptomatic infection with hepatitis A virus was confirmed in 25 contacts receiving vaccine (4.4%) and in 17 contacts receiving immune globulin (3.3%) (relative risk, 1.35; 95% confidence interval, 0.70 to 2.67).Low rates of hepatitis A in both groups indicate that hepatitis A vaccine and immune globulin provided good protection after exposure. Although the study's prespecified criterion for noninferiority was met, the slightly higher rates of hepatitis A among vaccine recipients may indicate a true modest difference in efficacy and might be clinically meaningful in some settings. Vaccine has other advantages, including long-term protection, and it may be a reasonable alternative to immune globulin for postexposure prophylaxis in many situations. (ClinicalTrials.gov number, NCT00139139 [ClinicalTrials.gov].).

Large outbreaks and sporadic cases of hepatitis E have been reported in Central Asia. We assessed the genetic relatedness of hepatitis E virus (HEV) strains from outbreak and sporadic cases in Turkmenistan. Specimens from outbreak and sporadic cases of acute hepatitis non-A, non-B were tested by reverse transcription (RT)-polymerase chain reaction (PCR) to identify the presence of HEV RNA; nucleotide sequences were analyzed. HEV RNA was detected from 23/156 (15%) outbreak cases and 2/23 (9%) sporadic cases. The HEV outbreak isolates represented 14 unique sequences with genetic distances varying between 0.3% and 8.6%, 12 of which were closely related, with distances between 0.3% and 5.6%. Two unique sequences from outbreak cases 32 and 42 were closely related (99.7%) and shared 91.8–93.4% of sequence with the other 12 strains. The two strains were closely related to the previously published isolates from Burma (99.7–100%) and India-Madras (95.7–96.1%). The two 1994 sporadic HEV strains were 97.4% distinct, wile revealing 91.4–94.1% homology to 1985 strains, and 94.4–94.7% to HEV from the neighboring China and Pakistan. Genetic diversity of HEV that caused the hepatitis E outbreak in Turkmenistan in 1985 suggests heterogeneity of viral sources. Sporadic hepatitis E that occurred in 1994 was caused by viral strains genetically distinct from those causing the outbreak in 1985, yet closely related to HEV from neighboring countries. The study suggests that circulation of a broad variety of strains of HEV may occur in Central Asia, regardless of international borders, presenting a significant public health threat to the population of the region. J. Med. Virol. 79:1696–1702, 2007. © 2007 Wiley-Liss, Inc.

Genetic recombination between different strains of Hepatitis C virus (HCV) was investigated in three chimpanzees inoculated experimentally with factor VIII concentrate containing HCV subgenotypes 1a, 1b, 2b and 3a. A 750 bp long fragment from the HCV envelope region was amplified by RT-PCR and quasispecies were isolated by plasmid cloning. Nucleotide sequences derived from isolated quasispecies were screened for the presence of inter-subgenotypic recombination by using sequence analysis. Recombination between HCV subgenotype 1a and 1b was found in two animals; each recombinant variant differed by location of predicted crossover region or order of subgenotype 1a and 1b sequences.

ContextNuclear pharmacies prepare radiopharmaceutical products for use in common diagnostic procedures, including myocardial perfusion studies. Hepatitis C virus (HCV) transmission has not been reported previously in the setting of nuclear imaging studies.ObjectiveTo investigate an outbreak of acute HCV infection identified among patients who underwent myocardial perfusion studies on October 15, 2004, using an injected radiopharmaceutical.Design, Setting, and PatientsOutbreak investigation including molecular epidemiology and pharmacy site investigation at outpatient cardiology clinics and a nuclear pharmacy in Maryland. Ninety patients who received injections drawn from select radiopharmaceutical vials prepared on October 14-15, 2004, at a single nuclear pharmacy were offered testing for bloodborne pathogens. Pharmacy procedures were reviewed and HCV quasi species analysis was performed.Main Outcome MeasuresHepatitis C virus infection and quasispecies sequence similarity.ResultsSixteen patients with acute HCV infection were identified from 3 separate clinics. All patients received radiopharmaceutical injections drawn from a single pharmacy vial (vial 1). None of the 59 tested patients who received doses from 6 other vials had acute HCV infection. Blood from a potential source patient with HCV and human immunodeficiency virus (HIV) infection was processed for a radiolabeled white blood cell study in the pharmacy 12 hours before vial 1 was prepared. The HCV quasispecies sequences from this potential source patient were nearly identical to those from cases (97.8%-98.5% similarity). No acute HIV infections were identified. Pharmacy practices that could have led to blood cross-contamination included reuse of needles and syringes during dilutions and use of common flow hoods for some steps in the preparation of sterile and blood-derived products.ConclusionsSixteen persons acquired HCV infection from a blood-contaminated radiopharmaceutical. The source and practices that could have facilitated breaks in aseptic technique were identified at the pharmacy. Nuclear pharmacies that handle biological products should follow appropriate aseptic technique to prevent contamination of sterile radiopharmaceuticals.

SUMMARYCurrent 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.

Perinatal infection with hepatitis B virus (HBV) may occur despite immunoprophylaxis. One of the important mechanisms for perinatal prophylaxis failure, might include HBV surface gene variants. Therefore, we screened Korean children, in whom perinatal prophylaxis failed, for HBV surface gene variants.Thirty-one children with perinatal HBV prophylaxis failure were selected. To amplify the major hydrophilic region of the HBV surface gene, nested PCR with primers targeted to nucleotides 237 to 706 was performed, and then sequencing was done.All cases were shown to be PCR positive for HBV-DNA and genotype C. Nine out of 31 (29%) with perinatal prophylaxis failure had a nucleotide substitution at the major hydrophilic region of the gene; but only two cases (6.5%) had an amino acid substitution. One case was infected by wild type and variants of I126S, and the other by wild type and S114A+I126S, respectively.In Korea, compared to the previous studies of other nations, gene surface variants such as G145R do not appear to play an important role in perinatal immunoprophylaxis failure.

This study determined whether selective transmission of hepatitis C virus (HCV) species occurred among human and chimpanzee recipients of contaminated blood products or plasma containing multiple genotypes, subgenotypes and quasispecies. Commercially prepared factor VIII concentrate (lot DO56), produced prior to HCV testing and inactivation, was subsequently found by direct cloning to contain the following subgenotypes: 1a and 1b (73 % of clones), 2a (13 % of clones), 2b (11 % of clones) and 3a (4 % of clones). A patient transfused with factor VIII concentrate DO56 was diagnosed with clinical non-A, non-B hepatitis and subsequently found to be infected with HCV subgenotype 1b. Among five chimpanzees inoculated experimentally with the same factor VIII concentrate, two were infected only with HCV subgenotype 1a and three were infected with approximately equivalent clonal proportions of subgenotypes 1a and 1b. HCV hypervariable region 1 (HVR1) quasispecies analysis of the DO56 factor VIII concentrate and a serum specimen from the single chimpanzee that developed a chronic HCV infection following inoculation with DO56 showed 0–56 % nucleotide variation. However, specimens from chimpanzees infected in the second to fourth passages of the DO56 inoculum had 0–8 % HVR1 quasispecies nucleotide variation. The high HVR1 quasispecies variation in the factor VIII concentrate and its first passage in chimpanzees indicates the presence of multiple HCV isolates, whereas the low variation in the second to fourth chimpanzee passages suggests transmission of a single HCV isolate. These findings strongly suggest selective transmission of HCV isolates during experimental chimpanzee infection and among humans exposed to multiple HCV species.

BACKGROUND Alaska Native (AN) children were at high risk of acquiring hepatitis B virus (HBV) infection before vaccination began in 1983. We evaluated the long-term protection from hepatitis B (HB) vaccination among AN children immunized when infants. METHODS During 1984-1995, we recruited a convenience sample of AN children who had received a three dose series of HB vaccine starting at birth and had serum antibody to hepatitis B (anti-HBs) concentrations of >/= 10 mIU/mL at 7-26 months of age. We evaluated anti-HBs concentrations and the presence of anti-HBc in participants' sera every other year up to age 16 years. Anti-HB core antigen (anti-HBc)-positive specimens were tested for hepatitis B surface antigen and for HBV DNA. RESULTS We followed 334 children for 3151 person-years (median, 10 years per child) with 1610 specimens collected. Anti-HBs concentrations dropped rapidly among all participants. Among children 2, 5 and 10 years of age, 37 of 79 (47%), 33 of 176 (19%) and 8 of 95 (8%), respectively, had anti-HBs concentrations of >/= 10 mIU/mL. Receipt of recombinant vaccine was significantly associated with a more rapid antibody decline (P < 0.001). Six (1.8%) children acquired anti-HBc, 3 of whom had definite breakthrough infections (at least 2 consecutive anti-HBc-positive specimens or at least 1 anti-HBc-positive specimen and HBV DNA detection by PCR). None of these children had detectable hepatitis B surface antigen, and none had symptoms of hepatitis. CONCLUSIONS Anti-HBs concentrations declined over time among AN infants successfully immunized with HB vaccine starting at birth. Transient anti-HBc appeared in a small percentage of children; however, none developed clinical signs of hepatitis or chronic HBV infection.

In November 2003, a large hepatitis A outbreak was identified among patrons of a single Pennsylvania restaurant. We investigated the cause of the outbreak and factors that contributed to its unprecedented size.Demographic and clinical outcome data were collected from patients with laboratory confirmation of hepatitis A, and restaurant workers were tested for hepatitis A. A case-control study was conducted among patrons who dined at the restaurant between October 3 and October 6, 2003. Sequence analysis was performed on a 315-nucleotide region of viral RNA extracted from serum specimens.Of 601 patients identified, 3 died; at least 124 were hospitalized. Of 425 patients who recalled a single dining date at the restaurant, 356 (84 percent) had dined there between October 3 and October 6. Among 240 patients in the case-control study, 218 had eaten mild salsa (91 percent), as compared with 45 of 130 controls (35 percent) (odds ratio, 19.6; 95 percent confidence interval, 11.0 to 34.9) for whom data were available. A total of 98 percent of patients and 58 percent of controls reported having eaten a menu item containing green onions (odds ratio, 33.3; 95 percent confidence interval, 12.8 to 86.2). All restaurant workers were tested, but none were identified who could have been the source of the outbreak. Sequences of hepatitis A virus from all 170 patients who were tested were identical. Mild salsa, which contained green onions grown in Mexico, was prepared in large batches at the restaurant and provided to all patrons.Green onions that were apparently contaminated before arrival at the restaurant caused this unusually large foodborne outbreak of hepatitis A. The inclusion of contaminated green onions in large batches that were served to all customers contributed to the size of the outbreak.

During January-April, 2000, 12 cases of acute hepatitis B were reported in Pierce County, Washington, compared with seven in all of 1999. Seven (58.3%) case patients were injection drug users (IDUs), three of whom were coinfected with hepatitis D virus (HDV) and died of fulminant hepatitis. Vaccination clinics were implemented at the local health department and needle exchange program to control the outbreak. We investigated this outbreak to determine risk factors for hepatitis B virus (HBV) transmission among IDUs. Hepatitis B cases were ascertained through routine surveillance and prevaccination testing at vaccination clinics. We conducted a case-control study comparing IDU case patients with HBV-susceptible IDUs identified at the vaccination clinics. Fifty-eight case patients were identified during January-December, 2000, 20 (34.5%) of whom were coinfected with HDV. Thirty-eight case patients (65.5%) reported current IDU. In the case-control study, the 17 case patients were more likely than the 141 controls to report having more than one sex partner [odds ratio (OR) =4.8, 95% confidence interval (CI) =1.5-15.0], injecting more than four times a day (OR = 4.5, 95% CI =1.2-15.6) and sharing drug cookers with more than two people (58.8% vs. 14.0%, OR =14.0, 95% CI =2.4-81.5). Results were similar after controlling for syringe sharing in multivariable analysis. IDUs should be vaccinated against hepatitis B and should be advised against sharing drug injection equipment.

Background & Aims: Estimates of the long-term benefits of antiviral therapies for chronic hepatitis C are influenced by the frequency of characteristics that affect response in the population treated. This study determined hepatitis C virus (HCV) genotypes and RNA titers among HCV-infected persons in the general population of the United States. Methods: Genotypes were determined from the NS5b region, and HCV RNA was quantified by using Amplicor Monitor (Roche Diagnostic Systems, Inc, Branchburg, NJ) from 275 HCV RNA–positive participants in the Third National Health and Nutrition Examination Survey conducted during 1988 to 1994. Results: The HCV genotypes identified included 1a (n = 142), 1b (n = 73), 2a (n = 8), 2b (n = 27), 3a (n = 17), 4 (n = 3), and 6 (n = 5). Based on weighted analysis of persons infected with genotypes 1, 2, and 3, genotype 1 predominated in all age groups (75.3%). By racial/ethnic group, genotype 1 was found in 90.9% of non-Hispanic blacks, 69.6% of non-Hispanic whites, and 71.2% of Mexican Americans. After adjusting for age and gender, only non-Hispanic black race/ethnicity was independently associated with genotype 1 infection (adjusted odds ratio 4.9; 95% confidence interval, 1.9–12.8). The overall geometric mean concentration of HCV RNA was 2.1 × 10 6 IU/mL; concentrations >2 million IU/mL were found in 53.0% overall and 50.3% of persons with genotype 1. Conclusions: Persons with chronic hepatitis C in the United States who may require treatment in the foreseeable future are predominantly infected with genotype 1, including a disproportionate number of non-Hispanic blacks. These features emphasize the need for improved therapies that reduce or eliminate complications from genotype 1 infections.

Background Molecular epidemiologic investigations can link geographically separate foodborne hepatitis A outbreaks but have not been used while field investigations are in progress. In 2003, outbreaks of foodborne hepatitis A were reported in multiple states. Methods Case-control studies were conducted in 3 states. Hepatitis A virus was sequenced from serologic specimens from individuals associated with outbreaks and from individuals concurrently ill with hepatitis A in non-outbreak settings in the United States and Mexico. Results Case-control studies in Tennessee (TN), North Carolina (NC), and Georgia (GA) found green onions to be associated with illness among restaurant patrons (TN: odds ratio [OR], 65.5 [95% confidence interval {CI}, 8.9-482.5; NC: OR, 2.4 [95% CI, 0.3-21.9]; GA: OR, 20.9 [95% CI, 3.9-110.3]). Viral sequences from TN case patients differed by 2 nt, compared with those from case patients in NC and GA. A third sequence, differing from the TN and GA/NC sequences by 1 nt, was identified among case patients in a subsequent outbreak in Pennsylvania. Each outbreak sequence was identical to > or =1 sequence isolated from northern Mexican resident(s) with hepatitis A. The sources of green onions served in restaurants in TN and GA were 3 farms in northern Mexico. Conclusions Ongoing viral strain surveillance facilitated the rapid implementation of control measures. Incorporation of molecular epidemiologic methods into routine hepatitis A surveillance would improve the detection of hepatitis A outbreaks and increase our understanding of hepatitis A epidemiology in the United States.

Background. The genetic relatedness of hepatitis A virus (HAV) isolates was determined to identify possible infection sources for case patients in the Sentinel Counties Study of Acute Viral Hepatitis. Methods. A 315-nucleotide segment of the VP1-P2 region of the HAV genome was amplified and sequenced from serum of case patients and analyzed together with risk-factor data. Results. Of 508 HAV-RNA–positive case patients, 449 (88.4%) were interviewed, and 255 (50.1%) reported 1 risk factor. Some 123 unique nucleotide sequence patterns (UNSPs) were identified—77 (62.6%) from only 1 case patient and the rest in 2–99 persons. Among international travelers, a single person was more often infected with a single type of UNSP (17/54 [31.5%]), compared with other case patients (48/393 [12.2%]; ). UNSPs P ! .001 from travelers to Mexico (33/37 [89.2%]) clustered with those from Hispanic children (47/49 [95.9%]). Of 119 men who had sex with men, 96 (80.7%) had the same or similar UNSPs, which were also found in 37 men and 10 women with no identified infection source. Conclusion. HAV is often transmitted within networks of persons with similar risk factors, which may be the infection source for others in the community.

Background: We report a case of simultaneous HIV and hepatitis C virus (HCV) transmission from a nursing home patient to a health care worker (HCW) whose HIV and HCV infections were diagnosed during routine blood donor screening. Methods: Detailed information about the HCW, possible occupational and nonoccupational blood and body fluid exposures, and possible source patient was collected. Blood samples were drawn from the HCW and patient, and HIV and HCV laboratory testing was performed at the Centers for Disease Control and Prevention. Results: The HCW, who worked as a nursing home aide, had no nonoccupational risk factors for HIV or HCV infection but provided care for 1 HIV-infected patient with dementia and urinary and fecal incontinence. The HCW had numerous exposures to the patient's emesis, feces, and urine to unprotected chapped and abraded hands. HCW and patient blood samples were positive for anti-HCV by enzyme immunoassay and recombinant immunoblot assay testing. The HCW's and patient's HCV were genotyped as 1a, and their HIV-1 was genotyped as subtype B. HIV and HCV ribonucleic acid (RNA) sequence analysis showed that the HCW's and patient's viruses were very closely related. Conclusions: HIV and HCV transmission from the patient to the HCW appears to have occurred through nonintact skin exposure. Bloodborne pathogen transmission may have been prevented in this situation by consistent, unfailing use of barrier precautions.

For reasons not yet determined, chronic liver disease (CLD) has been a leading cause of excess morbidity and mortality in central Harlem. We conducted a case series and case-control analysis of demographic, clinical, epidemiological, and alcohol-intake-related information from patients with CLD and age- and sex-matched hospitalized control patients. Patients' sera were tested for markers of viral hepatitis. The presumed etiology of CLD among case-patients was as follows: both alcohol abuse and hepatitis C virus (HCV) infection, 24 persons (46% of case-patients); alcohol abuse alone, 15 (29%); HCV infection alone, 6 (12%); both alcohol abuse and chronic hepatitis B virus (HBV) infection, 3 (6%); and 1 each (2%) from: 1) schistosomiasis, 2) sarcoidosis, 3) unknown causes, and 4) alcohol abuse, chronic HBV, and HCV combined. In the case-control analysis, patients who had both alcoholism and either HBV (odds ratio [OR]: 6.3; 95% CI: 0. 5-334) or HCV (OR: 2.9; 95% CI: 1.3-6.2) were at increased risk for CLD, whereas patients who had only one of these three factors were not at increased risk for CLD. Patients who tested positive for the hepatitis G virus (HGV) did not have a significantly increased risk of CLD, and neither severity of CLD nor mortality was greater among these patients. Most patients in central Harlem who had CLD had liver damage from a combination of alcohol abuse and chronic viral hepatitis. Alcohol and hepatitis viruses appear to be synergistically hepatotoxic; this synergy appears to explain both the high rate of CLD in central Harlem and the recent reductions in this rate. Persons at risk for chronic HBV and HCV infection should be counseled about their increased risk of CLD if they consume excessive alcohol. Morbidity and mortality from liver disease could be decreased further by a reduction in alcohol consumption among persons who have chronic HBV and HCV infection, avoidance of needle sharing, and hepatitis B vaccination.

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.

A simple system to detect polymerase chain reaction (PCR) amplification products was developed. This detection method has the sensitivity and the specificity of nested primer PCR amplification or Southern blot hybridization of PCR product. Digoxigenin-labeled PCR products were hybridized with a biotinylated probe in liquid phase and captured on to microtiter wells coated with antidigoxigenin followed by detection with streptavidin-peroxidase. The sensitivity of this assay for the detection of hepatitis A virus, hepatitis B virus, and hepatitis C virus is equal to that of existing nucleic acid detection systems.

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.

A new isolate of hepatitis A virus (HAV), CY-145, was isolated from stool specimens obtained from cynomologus macaques naturally infected with this agent. Sequence analysis of the capsid region of the genome indicated that this virus differed from other sequenced HAV strains by about 20% at the nucleotide level and 7% at the amino acid level. Two amino acid residues (residues 70 of VP3 and 102 of VP1), previously identified as constituting an immunodominant site and conserved in all sequenced HAVs, were changed in the CY-145 virus. Sequence analysis of a second cynomolgus HAV isolate (CY-55), which came from a different geographical location, showed the same amino acid replacement at these two sites. In addition both isolates had an amino acid substitution at the VP3-VP1 cleavage site. These data suggest that the cynomolgus HAV differs genetically and antigenically from all other sequenced HAVs.

IgM, IgG, and HBsAg containing circulating immune complexes (CIC) were determined, by conglutinin (K) and C1q assays, for assessing the role of CIC in hepatitis delta virus (HDV) infection in 54 HBsAg-negative controls and 85 HBsAg-positive patients with chronic hepatitis. The prevalence of HDV markers (HDV antigen and anti-HD) was 24.70% (21/85). CIC were a common feature of HDV infection with 95.24% of patients having at least one abnormal test result. The prevalence of elevated IgM-K, IgG-K, IgM-C1q, and IgG-C1q CIC were 85.71, 85.71, 57.14, and 85.71%, respectively. The prevalence of IgM class CIC were statistically higher in patients with HDV infection than in those without (P = .001 for the K assay and P = .023 for the C1q assay). There was no difference in the prevalence of IgG class CIC. Patients with HDV infection also have significantly higher median levels of IgM K-CIC (P = .002), IgG K-CIC (P = .049), and IgG C1q-CIC (P = .008). In patients with HDV infection, there was positive correlation between IgM C1q-CIC and transaminase levels (r = .519, P = .016 for AST; r = .500, P = .021 for ALT). There was no difference in the prevalence of HBsAg containing CIC between patients with HDV infection (76.19%) and those without (74.60%). In conclusion, IgM class CIC are the major CIC and correlate with disease activity in HDV infection. CIC may play a role in the pathogenesis of HDV infection.

Circulating immune complexes were isolated by conglutinin affinity chromatography during the course of hepatitis A virus infection in a chimpanzee. Characterization of circulating immune complexes showed that most of the hepatitis A virus-specific antibody was IgM, that IgG was present and that C3d and fibronectin were also present. Hepatitis A virus capsid polypeptides were identified in the circulating immune complexes and polypeptides in the molecular weight range of 63 to 67 kDa having immunological determinants common to both C3d and hepatitis A virus. Hepatitis A virus-RNA was detected in these circulating immune complexes using the polymerase chain reaction for in vitro amplification of nucleic acid and suggests the circulating immune complexes contain intact virus.

The duration of protection afforded by hepatitis B vaccination is unknown.To determine antibody persistence and protection from hepatitis B virus (HBV) infection.Prospective cohort study.15 villages in southwest Alaska.1578 Alaska Natives vaccinated at age 6 months or older.During 1981-1982, participants received 3 doses of plasma-derived hepatitis B vaccine. This cohort was followed annually over the first 11 years, and 841 (53%) persons were tested at 15 years.Antibody to hepatitis B surface antigen (anti-HBs), markers of HBV infection, and testing to identify HBV variants.Levels of anti-HBs in the cohort decreased from a geometric mean concentration of 822 mIU/mL after vaccination to 27 mIU/mL at 15 years. Initial anti-HBs level, older age at vaccination, and male sex were associated with persistence of higher anti-HBs levels at 15 years when analyzed by a longitudinal linear mixed model. After adjustment for initial anti-HBs level and sex, those vaccinated at age 6 months to 4 years had the lowest anti-HBs level at 15 years. Asymptomatic breakthrough infections were detected in 16 participants and occurred more frequently in persons who did not respond to vaccination than those who responded (P = 0.01). Among infected persons with viremia, 2 were infected with wild-type HBV and 4 had HBV surface glycoprotein variants, generally accompanied by wild-type HBV.The loss of participants to follow-up at 15 years was 47%. However, characteristics of persons tested were similar to those of persons lost to follow-up.Hepatitis B vaccination strongly protected against infection for at least 15 years in all age groups. Antibody levels decreased the most among persons immunized at 4 years of age or younger.

Background An anesthesiologist was diagnosed as having acute hepatitis C 3 days after providing anesthesia during the thoracotomy of a 64-year-old man (patient A). Eight weeks later, patient A was diagnosed as having acute hepatitis C. Methods We performed tests for antibody to hepatitis C virus (HCV) on serum samples from the thoracotomy surgical team and from surgical patients at the 2 hospitals where the anesthesiologist worked before and after his illness. We determined the genetic relatedness of the HCV isolates by sequencing the quasispecies from hypervariable region 1. Results Of the surgical team members, only the anesthesiologist was positive for antibody to HCV. Of the 348 surgical patients treated by him and tested, 6 were positive for antibody to HCV. Of these 6 patients, isolates from 2 (patients A and B) were the same genotype (1a) as that of the anesthesiologist. The quasispecies sequences of these 3 isolates clustered with nucleotide identity of 97.8% to 100.0%. Patient B was positive for antibody to HCV before her surgery 9 weeks before the anesthesiologist's illness onset. The anesthesiologist did not perform any exposure-prone invasive procedures, and no breaks in technique or incidents were reported. He denied risk factors for HCV. Conclusions Our investigation suggests that the anesthesiologist acquired HCV infection from patient B and transmitted HCV to patient A. No further transmission was identified. Although we did not establish how transmission occurred in this instance, the one previous report of bloodborne pathogen transmission to patients from an anesthesiologist involved reuse of needles for self-injection.

Circulating immune complexes (CICs) were detected during the course of experimental hepatitis A virus (HAV) infection in 8 of 9 chimpanzees. In all cases, the predominant class of antibody detected in the CIC was IgM. The appearance of IgM-CIC usually preceded the onset of liver enzyme elevations, and in all instances, the appearance of IgM-CIC correlated with the presence of IgM anti-HAV. Six of 8 animals tested had significant depression of C3 concentrations during the course of infection, and this depression occurred at the peak of CIC activity. Immunohistologic studies demonstrated granular deposits of IgM localized in sinusoidal cells during peak of IgM-CIC activity. IgM-CICs appear to be a fairly consistent finding during HAV infection and probably represent the viremic phase of the disease. However, they do not appear to mediate hepatocellular injury by direct action on hepatocytes.

In the newborn infant the IgM antibody response to viral infections has been used for diagnostic purposes, especially when transplacentally acquired maternal IgG antibody has also been present. 1 Infants born to women who are chronic carriers of hepatitis B virus have a high likelihood of becoming infected during the perinatal period and remaining chronically infected with HBV. 2, 3 In adults, one of the earliest events in the immune response to HBV infection has been the IgM antibody response to hepatitis B core antigen. 4 Several reports indicate that this antibody response was not detectable in perinatal HBV infection, s,6 but possible explanations for the lack of the IgM anti-HBc response during perinatal HBV infection have not been examined. METHODS The infants in this study were in a previously described double-blind placebo-controlled trial to determine the efficacy of hepatitis B vaccine in the prevention of perinatal HBV infection. 3 Infants were born to mothers with detectable hepatitis B surface antigen, and maternal hepatitis B e antigen status was used for random assignment to treatment groups. An infant was considered to have had an HBV infection if a serum specimen (venous) was positive for

Immune complexes have been implicated in the pathogenesis of a number of infectious diseases. The predominant immunoglobulin class associated with circulating immune complexes is IgG, although immune complexes containing IgM have been described. The role of IgM immune complexes in disease pathogenesis has been difficult to characterize due to the lack of a reliable in vitro model. Immunoglobulins aggregated with bis-diazotized benzidine (BDB) are known to function as model immune complexes. We have developed an IgM immune complex using BDB-aggregated IgM which can be used as a reference in a conglutinin-based immune complex assay. Using this assay system, humans and chimpanzees with acute hepatitis A were found to have circulating immune complexes that contained IgM as the predominant antibody.