Analysis of the circulation of hepatitis A virus in Argentina since vaccine introduction

Hepatitis A virus subgenotypes in Latvia, 2008-2021

BACKGROUND

In Latvia outbreaks of the HAV were observed between 2008 and early 2010 and again in 2017-2018. However, the risks of introducing and spreading infection still exist, as the virus spreads easily when personal hygiene is not followed.

METHODS

To determine the spread of HAV subgenotypes in the territory of Latvia the VP1/P2A genomic region of HAV was amplified and sequenced for 259 case serum samples. The study carried out a molecular biological investigation and molecular epidemiological investigation. Demographic data (sex, age), disease data (hepatitis symptoms, hospitalization, vaccination) and epidemiology data (part of the outbreak, possible source of infection, recent travel) were collected. Based on the obtained sequences, the phylogenetic tree was built and analyzed for the homology and belonging to different isolated HAV clusters from other countries.

RESULTS

From the obtained data, it was concluded that HAV subgenotype IA had 13 clusters and 12 sporadic cases, HAV subgenotype IB had eight clusters and 11 sporadic cases, HAV subgenotype IIIA had one cluster and nine sporadic cases. It was found that the sources of infection among the investigated cases were different, they were mostly associated with contact with a patient with HAV, travel, as well as between persons who inject drugs and men who have sex with men, and the prevalence of HAV similar sequences was observed in different years. It was concluded that patients with HAV subgenotype IA had the longest hospitalization duration and averaged 9.3 days, while patients with subgenotype IB - 7.3 days, subgenotype IIIA - 7.7 days. Analyzing the data on vaccination, it was found that mostly all were not vaccinated or had an unknown vaccination status.

CONCLUSIONS

All of this has led to the conclusion that the application of molecular biological methods of the HAV and a careful analysis of epidemiological data can help to better understand the ways of spreading the infection, investigate local outbreaks, detect cases of imported infection and track the recirculation of the virus.

Hepatitis A virus monitoring in wastewater: A complementary tool to clinical surveillance

Monitoring wastewater is an effective tool for tracking information on trends of enteric viral dissemination. This study aimed to perform molecular detection and genetic characterization of HAV in wastewater and to correlate the results with those obtained from clinical surveillance. Wastewater samples (n=811) of the second most populous city in Argentina were collected from the main wastewater treatment plant (BG-WWTP, n=261), and at 7 local neighborhood collector sewers (LNCS, n=550) during 2017-2022. Clinical samples of acute hepatitis A cases (HA, n=54) were also analyzed. HAV molecular detection was performed by real time RT-PCR, and genetic characterization by RT-Nested PCR, sequencing and phylogenetic analysis. RNA-HAV was detected in sewage samples throughout the entire period studied, and detection frequencies varied according to the location and year (2.9% - 56.5%). In BG-WWTP, 23% of the samples were RNA-HAV+. The highest detection rates were in 2017 (30.0%), 2018 (41.7%) and 2022 (56.5%), which coincides with the highest number of HA cases reported. Twenty-eight (28) sequences were obtained (from clinical and sewage samples), and all were genotype IA. Two monophyletic clusters were identified: one that grouped clinical and wastewater samples from 2017-2018, and another with specimens from 2022, evidencing that environmental surveillance might constitute a replica of viral circulation in the population. These findings evidence that WBE, in a centralized and decentralized sewage monitoring, might be an effective strategy to track HAV circulation trends over time, contributing to the knowledge of HAV in the new post-vaccination epidemiological scenarios in Argentina and in Latin America.

High prevalence of hepatitis A and E viruses in environmental and clinical samples from West Argentina

Environmental surveillance of water sources is important to monitoring viral hepatitis transmission in clinical settings. This study investigated the circulation of hepatitis A (HAV) and E (HEV) viruses in sewage and clinical samples from Argentina. Between 2016 and 2017, 80 raw sewage samples and 86 clinical samples (stool and serum) from suspected cases of hepatitis A and hepatitis E were obtained. HAV and HEV were tested by both real-time and nested PCR. Positive samples were sequenced for genotype determination and phylogenetic analysis. Overall, HAV was recovered in 39% of sewage samples and 61.1% of clinical samples. HEV was detected in 22.5% of sewage samples and 15.9% of clinical samples. HAV was found more frequently in sewage during the winter and in clinical samples in spring; HEV was more prevalent in sewage during summer and in clinical samples in autumn. All HAV isolates belonged to genotype IA and HEV isolates belonged to genotype 3, the most prevalent genotypes in South America. High prevalence of HAV and HEV in environmental and clinical samples in Mendoza, Argentina was observed. These findings reinforce the importance of environmental surveillance and implementation of health strategies to control the spread of HAV and HEV in developing countries.

Tracking SARS-CoV-2 in rivers as a tool for epidemiological surveillance

The aim of this work was to evaluate if rivers could be used for SARS-CoV-2 surveillance. Five sampling points from three rivers (AR-1 and AR-2 in Arenales River, MR-1 and MR-2 in Mojotoro River, and CR in La Caldera River) from Salta (Argentina), two of them receiving discharges from wastewater plants (WWTP), were monitored from July to December 2020. Fifteen water samples from each point (75 in total) were collected and characterized physico-chemically and microbiologically and SARS-CoV-2 was quantified by RT-qPCR. Also, two targets linked to human contributions, human polyomavirus (HPyV) and RNase P, were quantified and used to normalize SARS-CoV-2 concentration, which was compared to reported COVID-19 cases. Statistical analyses allowed us to verify the correlation between SARS-CoV-2 and the concentration of fecal indicator bacteria (FIB), as well as to find similarities and differences between sampling points. La Caldera River showed the best water quality; FIBs were within acceptable limits for recreational activities. Mojotoro River's water quality was not affected by the northern WWTP of the city. Instead, Arenales River presented the poorest water quality; at AR-2 was negatively affected by the discharges of the southern WWTP, which contributed to significant increase of fecal contamination. SARS-CoV-2 was found in about half of samples in low concentrations in La Caldera and Mojotoro Rivers, while it was high and persistent in Arenales River. No human tracers were detected in CR, only HPyV was found in MR-1, MR-2 and AR-1, and both were quantified in AR-2. The experimental and normalized viral concentrations strongly correlated with reported COVID-19 cases; thus, Arenales River at AR-2 reflected the epidemiological situation of the city. This is the first study showing the dynamic of SARS-CoV-2 concentration in an urban river highly impacted by wastewater and proved that can be used for SARS-CoV-2 surveillance to support health authorities.

Tracking SARS-CoV-2 in rivers as a tool for epidemiological surveillance

The aim of this work was to evaluate if rivers could be used for SARS-CoV-2 surveillance. Five sampling points from three rivers (AR-1 and AR-2 in Arenales River, MR-1 and MR-2 in Mojotoro River, and CR in La Caldera River) from Salta (Argentina), two of them receiving discharges from wastewater plants (WWTP), were monitored from July to December 2020. Fifteen water samples from each point (75 in total) were collected and characterized physico-chemically and microbiologically and SARS-CoV-2 was quantified by RT-qPCR. Also, two targets linked to human contributions, human polyomavirus (HPyV) and RNase P, were quantified and used to normalize SARS-CoV-2 concentration, which was compared to reported COVID-19 cases. Statistical analyses allowed us to verify the correlation between SARS-CoV-2 and the concentration of fecal indicator bacteria (FIB), as well as to find similarities and differences between sampling points. La Caldera River showed the best water quality; FIBs were within acceptable limits for recreational activities. Mojotoro River's water quality was not affected by the northern WWTP of the city. Instead, Arenales River presented the poorest water quality; at AR-2 was negatively affected by the discharges of the southern WWTP, which contributed to significant increase of fecal contamination. SARS-CoV-2 was found in about half of samples in low concentrations in La Caldera and Mojotoro Rivers, while it was high and persistent in Arenales River. No human tracers were detected in CR, only HPyV was found in MR-1, MR-2 and AR-1, and both were quantified in AR-2. The experimental and normalized viral concentrations strongly correlated with reported COVID-19 cases; thus, Arenales River at AR-2 reflected the epidemiological situation of the city. This is the first study showing the dynamic of SARS-CoV-2 concentration in an urban river highly impacted by wastewater and proved that can be used for SARS-CoV-2 surveillance to support health authorities.

Outbreak of hepatitis A in a post-vaccination era: High rate of co-infection with sexually transmitted diseases

INTRODUCTION AND OBJECTIVES

After hepatitis A (HAV) mandatory immunization in 2005 in Argentina, the incidence of HAV declined drastically. However, several new autochthonous cases of HAV have been reported since 2017. We aimed to evaluate the clinical and epidemiological characteristics and possible transmission routes of affected patients.

PATIENTS OR MATERIALS AND METHODS

We performed a cross-sectional study of patients residing in Argentina with acute hepatitis A between 30.06.2017 and 31.12.2018.

RESULTS

66 cases of HAV were registered. Fifty-six patients (86%) were males, with a mean age of 34 ± 12 years old. The most likely routes of transmission were sexual intercourse of men with men, reported by 31 patients. Additionally, 23% and 26% of patients tested positive for HIV and syphilis, respectively. In total, 35% of patients required hospitalization. When assessing outcomes, 79% had a mild presentation and 21% had a severe/fulminant presentation: one patient underwent liver transplantation, and one patient died.

CONCLUSIONS

Our study describes that during the study period, HAV infection affected predominantly young adults, particularly men who have sex with men. An elevated proportion of them was diagnosed with a concomitant sexually transmitted disease, and several patients had a severe presentation of the disease.

HAV infection in Brazilian men who have sex with men: The importance of surveillance to avoid outbreaks

Background

Hepatitis A is a fecal-oral infection caused by hepatitis A virus (HAV). Men who have sex with men (MSM) and transgender women (TW) have been reported as target groups for HAV infection. This study aimed to determine the seroprevalence, risk factors, and circulating strains associated with HAV infection among MSM and TW in Central Brazil.

Methods

A cross-sectional study was conducted from November 2011 to September 2013. Serum samples were collected from 425 individuals for anti-HAV antibody testing and HAV molecular characterization. Of them, 149 (35.1%) participants were self-identified as transgender women. Statistical analysis was performed to evaluate the risk factors of HAV seropositivity.

Results

The seroprevalence of HAV exposure was 69.7% (95% Confidence Interval: 65.3–74.0%). Serological evidence of HAV was significantly higher in participants who self-identified as transgender women (83.2%) than MSM (62.3%). Increasing age, non-white race, and lower monthly household income were independently associated with HAV exposure among MSM. Only lower monthly household income was independently associated with HAV exposure among TW. One anti-HAV IgM positive sample, from a transgender woman (0.2%), was detected and classified as subgenotype IA.

Conclusions

High HAV prevalence was observed, markedly among TW. Considering the risky sexual behaviors this population is exposed to, HAV vaccination and prevention programs targeting this population should be considered to prevent outbreaks and the burden of the disease.

Hepatitis A vaccination and its immunological and epidemiological long-term effects - a review of the evidence

Hepatitis A virus (HAV) infections continue to represent a significant disease burden causing approximately 200 million infections, 30 million symptomatic illnesses and 30,000 deaths each year. Effective and safe hepatitis A vaccines have been available since the early 1990s. Initially developed for individual prophylaxis, HAV vaccines are now increasingly used to control hepatitis A in endemic areas. The human enteral HAV is eradicable in principle, however, HAV eradication is currently not being pursued. Inactivated HAV vaccines are safe and, after two doses, elicit seroprotection in healthy children, adolescents, and young adults for an estimated 30-40 years, if not lifelong, with no need for a later second booster. The long-term effects of the single-dose live-attenuated HAV vaccines are less well documented but available data suggest they are safe and provide long-lasting immunity and protection. A universal mass vaccination strategy (UMV) based on two doses of inactivated vaccine is commonly implemented in endemic countries and eliminates clinical hepatitis A disease in toddlers within a few years. Consequently, older age groups also benefit due to the herd protection effects. Single-dose UMV programs have shown promising outcomes but need to be monitored for many more years in order to document an effective immune memory persistence. In non-endemic countries, prevention efforts need to focus on 'new' risk groups, such as men having sex with men, prisoners, the homeless, and families visiting friends and relatives in endemic countries. This narrative review presents the current evidence regarding the immunological and epidemiological long-term effects of the hepatitis A vaccination and finally discusses emerging issues and areas for research.

Persistent Detection of Cosavirus and Saffold Cardiovirus in Riachuelo River, Argentina

Cosaviruses (CoSV) and Saffold cardiovirus (SAFV) are novel members of the Picornaviridae family. The Matanza-Riachuelo river basin covers a total area of 2200 km² with approximately 60 km long. Its last section is called Riachuelo River. The aim of this study was to describe the circulation of both picornaviruses and their relationship with the environmental situation of the Riachuelo River using 274 samples collected from 2005 to 2015. CoSV and SAFV were investigated in samples available by two periods: 2005-2006 and 2014-2015 (103 and 101, respectively). Physicochemical and bacteriological parameters confirmed very high levels of human fecal contamination during the 11 years evaluated. CoSV was detected in 85.7% (66/77) and 65.4% (17/26) of the samples collected in 2005-2006 and 2014-2015 periods, respectively. Species A and D were identified, the first one being widely predominant: 74.1% (20/27) and 75.0% (3/4) in both periods. SAFV virus was detected in 47.1% (32/68) and 52.6% (10/19) in periods 2005-2006 and 2014-2015, respectively. SAFV-6 was the most identified genotype in the entire study, while SAFV-3 was predominant in 2005-2006. The contribution of genotypes 1, 2, 4 and 8 was minor. The high prevalence of CoSV and SAFV suggests that both viruses have been circulating in Argentina at least since 2005. Our results show that a watercourse with high rates of human fecal contamination can become a persistent source of new viruses which capacity to produce human diseases is unknown.

One or two doses of hepatitis A vaccine in universal vaccination programs in children in 2020: A systematic review

BACKGROUND

Hepatitis A virus (HAV) is a global health concern as outbreaks continue to occur. Since 1999, several countries have introduced universal vaccination (UV) of children against HAV according to approved two-dose schedules. Other countries have implemented one-dose UV programs since 2005; the long-term impact of this schedule is not yet known.

METHODS

We conducted a systematic literature search in four electronic databases for data published between January 2000 and July 2019 to assess evidence for one-dose and two-dose UV of children with non-live HAV vaccines and describe their global impact on incidence, mortality, and severity of hepatitis A, vaccine effectiveness, vaccine efficacy, and antibody persistence.

RESULTS

Of 3739 records screened, 33 peer-reviewed articles and one conference abstract were included. Rapid declines in incidence of hepatitis A and related outcomes were observed in all age groups post-introduction of UV programs, which persisted for at least 14 years for two-dose and six years for one-dose programs according to respective study durations. Vaccine effectiveness was ≥95% over 3-5 years for two-dose programs. Vaccine efficacy was >98% over 0.1-7.5 years for one-dose vaccination. Antibody persistence in vaccinated individuals was documented for up to 15 years (≥90%) and ten years (≥74%) for two-dose and one-dose schedules, respectively.

CONCLUSION

Experience with two-dose UV of children against HAV is extensive, demonstrating an impact on the incidence of hepatitis A and antibody persistence for at least 15 years in many countries globally. Because evidence is more limited for one-dose UV, we were unable to draw conclusions on immune response persistence beyond ten years or the need for booster doses later in life. Ongoing epidemiological monitoring is essential in countries implementing one-dose UV against HAV. Based on current evidence, two doses of non-live HAV vaccines are needed to ensure long-term protection.

Rotavirus contamination of surface waters from the northwest of Argentina

Fecal pollution of water is a serious concern because it is associated with the transmission of pathogens. The aim of this study was to analyze the occurrence of group A rotavirus (RVA) in surface waters from the Arias-Arenales River in Salta, a northern city in Argentina, and to define possible sources of fecal viral pollution. A total of 116 water samples were analyzed and RVA was detected in 3.4% (95% CI: 0.1-7.0%), with concentrations ranging from 1.9 × 10⁵ to 3.8 × 10⁶ genome copies per liter. RVA strains were characterized as G1P[8], G4P[8] and G9P[8], which are common genotypes circulating in the local population. The Arias-Arenales River presented unusual and sporadic contamination by RVA, originated from stormwater discharges and a variety of non-identified sources, and support the essential need of viral indicators for enhanced monitoring of water quality.

Molecular epidemiology of hepatitis A outbreaks in two districts in Indonesia in 2018: Same subtype, but different strains

The present study aimed to analyse molecular epidemiological data from hepatitis A virus (HAV) outbreaks in two affected areas. The association between the knowledge of hepatitis A and incidence of infection was also determined. Serum samples were obtained from 88 individuals with clinical manifestations of acute hepatitis in Lamongan (n=54) in January 2018 and Bangkalan (n=34) in March 2018. The outbreak investigation was started one day after the outbreaks were reported by the Public Health Offices in Lamongan and Bangkalan. Anti-HAV immunoglobulin M (IgM) and PCR amplification products of the VP1 capsid protein-P2A protease and VP1-VP3 junctions were analysed. Positive PCR products were sequenced, and a phylogenetic tree was constructed using Molecular Evolutionary Genetics Analysis X software. The control group comprised healthy students and staff members from the two affected areas. Thus, 172 responses from the control and hepatitis A case groups were analysed to assess the association between the students' knowledge level and the incidence of HAV infection. A total of 32 (59.25%) of the 54 individuals from Lamongan and 19 (55.9%) of the 34 participants from Bangkalan were positive for anti-HAV IgM; 26 PCR tests were positive in the VP3-VP1 and/or VP1-P2A junction, which were identified as HAV subgenotype IA. The subtype of HAV in the two areas was IA, similar to those identified previously, but the viruses did not originate from the same strain, as identified by multiple alignment. The knowledge level of the students and staff members in Lamongan studying and working at a half-day school exhibited a significant association with the incidence; however, no association was observed among the students in Bangkalan studying at a full-day school with a dormitory.

Viral hepatitis and Treponema pallidum prevalence in persons who underwent premarital blood tests in Argentina

The objective of this study was to estimate the prevalence of different serological markers of hepatitis A, B and C viruses and Treponema pallidum among the adult population of Argentina. To achieve this, adults who attended health services for premarital exams (which are mandatory and includes screening for syphilis) were recruited. A cross-sectional study was designed with a cluster sampling strategy. Couples who attended selected health services for premarital screening between 2013 and 2014 in Buenos Aires, Cordoba, Mendoza and Santa Fe provinces were included. A total of 3833 individuals were recruited. Anti-HAV prevalence was 63.9%, anti-HCV 0.3%, anti-HBc (without HBsAg) 1.9%, HBsAg 0.3%, and T pallidum 0.8%. Anti-HAV was higher among older participants, foreigners and those from the lower strata. HBV increased with age and was higher among foreigners and those with lower formal educational level. Anti-HCV frequency increased with age. Premarital screening of viral hepatitis could constitute an instance of diagnosis, vaccination and inclusion in care of those in need. Results from this study will allow the national hepatitis programs to design public policies in order to diminish the impact of these infections on the population.

Hepatitis A Virus, Hepatitis E Virus, and Rotavirus in Foods of Animal Origin Traded at the Borders of Brazil, Argentina, and Uruguay

The aim of this study was to investigate hepatitis A virus (HAV), hepatitis E (HEV), and rotavirus (RV) in fresh and processed meat traded on the border of Brazil with Argentina and Uruguay. In total, 159 samples of raw and processed foods of animal origin were collected in Paso de los Libres, Argentina (n = 53 raw meat, n = 24 processed meat) and Rivera, Uruguay (n = 55 raw meat, n = 18 processed meat), or were seized by the Brazilian International Agricultural Surveillance System-VIGIAGRO (Brazil-Argentina border) (n = 8 raw meat, n = 1 bush meat). All samples were tested for the presence of HAV, HEV, and RV genomes. HAV genes were detected in 18.23% of samples and RV genes in 23.89%. No HEV-positive samples were detected. HAV was also detected in two of the VIGIAGRO samples. Processed meats from Argentina and Uruguay had a higher rate of HAV and RV than raw meat (P > 0.05). The median HAV in the Argentinian and Uruguayan samples was 6.9 × 10⁴ and 3.5 × 10³ copies/g, respectively. The presence of RV viral genes in raw meats from Argentina was significant, and this was not observed in processed meats. The presence of HAV and RV genes in a significant portion of products from Argentina and Uruguay is a potential source of human infection. This also indicates precarious conditions of acquisition, processing, and manipulation, which could be improved by improved regulation of food across borders.

Infectious diseases in the era of refugees: Hepatitis A outbreak in Lebanon

BACKGROUND

The Syrian crisis has altered the epidemiology of infectious diseases in countries hosting large numbers of refugees. Lebanon witnessed several outbreaks linked to the presence of significant numbers of Syrian refugees, namely, Hepatitis A virus (HAV). We explore the epidemiology of HAV in Lebanon and the impact of the Syrian war during the 2014 outbreak and suggest solutions to prevent and minimize the HAV spread amid the current socioeconomic conditions.

METHODS

We reviewed all HAV cases reported to the Epidemiologic Surveillance Unit at the Ministry of Public Health between January 2001 and December 2017. Demographics and distribution of Syrian refugees in Lebanon were linked to reports of new HAV cases.

RESULTS

A sharp rise in the number of reported HAV cases was observed in Lebanon in 2013, concurrent with the Syrian crisis and influx of refugees. Most cases reported in 2013 and 2014 involved Syrian refugees and their relevant areas of settlement in the Beqaa and North governorates.

CONCLUSION

The influx of refugees strained overburdened sanitary infrastructure and overstretched existing public health services in Lebanon, which led to an increase in the incidence of reported HAV cases. The Lebanese health authorities and the international community need to intensify their efforts in surveillance and prevention of communicable diseases. Providing proper sanitation and free vaccination for affected communities are effective solutions to contain the HAV outbreak. Yet, financial constraints and the need to prioritize in the health budget put HAV-immunization at a lower priority. The Lebanese scenario could be reflective to other countries hosting sizeable numbers of refugees.

Tracking enteric viruses in green vegetables from central Argentina: potential association with viral contamination of irrigation waters

Consumption of green vegetable products is commonly viewed as a potential risk factor for infection with enteric viruses. The link between vegetable crops and fecally contaminated irrigation water establishes an environmental scenario that can result in a risk to human health. The aim of this work was to analyze the enteric viral quality in leafy green vegetables from Córdoba (Argentina) and its potential association with viral contamination of irrigation waters. During July-December 2012, vegetables were collected from peri-urban green farms (n = 19) and its corresponding urban river irrigation waters (n = 12). Also, urban sewage samples (n = 6) were collected to analyze the viral variants circulating in the community. Viruses were eluted and concentrated by polyethylene glycol precipitation and then were subject to Reverse Transcription Polymerase Chain Reaction to assess the genome presence of norovirus, rotavirus and human astrovirus. The concentrates were also inoculated in HEp-2 (Human Epidermoid carcinoma strain #2) cells to monitor the occurrence of infective enterovirus. The frequency of detection of the viral groups in sewage, irrigation water and crops was: norovirus 100%, 67% and 58%, rotavirus 100%, 75% and 5%, astrovirus 83%, 75% and 32% and infective enterovirus 50%, 33% and 79%, respectively. A similar profile in sewage, irrigation water and green vegetables was observed for norovirus genogroups (I and II) distribution as well as for rotavirus and astrovirus G-types. These results provide the first data for Argentina pointing out that green leafy vegetables are contaminated with a broad range of enteric viruses and that the irrigation water would be a source of contamination. The presence of viral genomes and infective particles in food that in general suffer minimal treatment before consumption underlines that green crops can act as potential sources of enteric virus transmission. Public intervention in the use of the river waters as irrigation source is needed.

Enteric Viruses in Surface Waters from Argentina: Molecular and Viable-Virus Detection

Water resources contaminated with wastewater are an important source for the dissemination of enteric viruses with an impact on the health of the population. The aim of the study was to assess the viral contamination of freshwater from a dam in Argentina by using infectious enterovirus detection, viral RNA amplification, and a genetic characterization of five enteric viruses associated with diarrhea and hepatitis. Enterovirus infectivity (iEV) was evaluated by cell culture and direct immunofluorescence. The detection of the viral genome of rotavirus (RV), human astrovirus (HAstV), norovirus (NoV), hepatitis A virus (HAV), and hepatitis E virus (HEV) was performed by reverse transcriptase PCR (RT-PCR). A total of 48 water samples from 4 monitoring points on the body of the dam from January to December 2012 and 66 water samples from 3 tourist beaches on the edge of the dam from October 2013 to October 2015 were collected monthly. During the first period, the overall viral frequency detection was 52.1% for group A RV, 50% for HAstV, 60.4% for NoV, 22.9% for HAV, 2.1% for HEV, and 64.6% for iEV. The overall frequency detection for the second sampling was 18.2% for RV and HAstV, 31.8% for NoV, 7.57% for HEV, and 66.7% for iEV. There was no detection of HAV during this period. The genotypes and genogroups detected through the study correlated with the most common genomic variants associated with human gastrointestinal and hepatitis illnesses. The results obtained could alert the health systems and environmental sanitation to make decisions for viral control and prevention in our environment.IMPORTANCE The study shows the impact of anthropic contamination of one of the most important tourist water resources in Argentina. This course of recreational water would be a favorable scenario for infection, as well as a reservoir for the enteric viruses, creating a risk for the population exposed to these waters. The results obtained could alert the health systems and environmental sanitation to make decisions for the control and prevention of viral diseases in this environment.

Metagenomic analysis reveals Hepatitis A virus in suspected yellow fever cases in Brazil

Using a metagenomic approach, we identified hepatitis A virus among cases of acute febrile illnesses that occurred in 2008-2012 in Brazil suspected as yellow fever. These findings reinforce the challenge facing routine clinical diagnosis in complex epidemiological scenarios.

Single-dose Universal Hepatitis A Immunization in One-year-old Children in Argentina: High Prevalence of Protective Antibodies up to 9 Years After Vaccination

BACKGROUND

Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children 12 months of age in 2005. Previous studies demonstrated high prevalence of protective antibody response 4 years after single-dose vaccination. This study assessed long-term seroprotection against HAV after vaccination.

METHODS

Children who received 1 dose of HAV vaccine at 1 year of age at least 6 years before enrollment were included at 5 centers in Argentina between 2013 and 2014. Demographic and socioeconomic characteristics were collected through a questionnaire. Blood samples were tested for anti-HAV antibodies. Antibody values ≥10 mIU/mL were considered seroprotective. Logistic regression analysis was performed to evaluate the association between demographic and socioeconomic variables and seroprotection.

RESULTS

A total of 1088 children were included, with a median postvaccination interval of 7.7 years (range 6.3-9.2 years). Of these children, 97.4% (95% confidence interval: 96.3%-98.3%) had protective antibodies against HAV. No association between demographic or socioeconomic variables and seroprotection was found. Geometric mean concentration of antibody levels against HAV was 170.5 mUI/mL (95% confidence interval: 163.2-178.2 mUI/mL).

CONCLUSIONS

Single-dose universal hepatitis A immunization in 1-year-old children resulted in sustained immunologic protection for up to 9 years in Argentina. These findings, along with the low current disease burden, confirm the success of the intervention.

High diversity of human polyomaviruses in environmental and clinical samples in Argentina: Detection of JC, BK, Merkel-cell, Malawi, and human 6 and 7 polyomaviruses

New human polyomaviruses have been recently described. The aim of this work was to detect and characterize human polyomaviruses circulating in Argentina by recovering viruses from environmental and sewage samples and evaluating their potential role as viral indicators of human waste contamination. Analysis was performed in a wider context including viruses from clinical samples from an immunocompromised population. River water and sewage samples were analyzed as a strategy to study the molecular epidemiology of viruses excreted by millions of people. Samples belonged to the Matanza-Riachuelo River (2005-2006: n=25 and 2012: n=20) and sewage from Buenos Aires city and suburbs (2011 and 2013: n=24). Viral detection was performed by PCR and the amplified viral genomes were characterized by phylogenetic analysis. Polyomaviruses were detected in 95.8% of sewage samples, identifying BKPyV (87.5%), JCPyV (83.3%), MCPyV (8.3%) and HPyV6 (8.3%). Besides, one sample collected in 2009 resulted positive for HPyV7. In 2005-2006, polyomaviruses were detected in 84.0% of river water samples, with the highest detection for MCPyV (52.0%), followed by BKPyV (44.0%), JCPyV (20.0%) and MWPyV (4.0%). In 2012, polyomaviruses were detected in 85.0% of river samples, finding JCPyV (85.0%), BKPyV (75.0%), MCPyV (25.0%) and HPyV6 (25.0%). Also, polyomaviruses, including JCPyV, BKPyV and MCPyV, were detected in 63.2% of urine samples from patients infected with HIV (n=19). Characterization indicated the coexistence of different genotypes and variants for each virus, particularly in sewage. MCPyV sequences (the only sequences from Argentina) formed a monophyletic group with the single sequence available for South America (French Guiana). The high level of detection and viral diversity found by environmental surveillance, which involved the characterization of viruses not previously described in South America, reinforces the usefulness of this approach to monitor viral contamination and describe the viral epidemiology in the general population.

Single-Dose Universal Hepatitis A Immunization in Argentina: Low Viral Circulation and High Persistence of Protective Antibodies Up to 4 Years

BACKGROUND

Single-dose hepatitis A virus (HAV) vaccination was implemented in all Argentinean children aged 12 months in 2005. Between 2005 and 2011, a dramatic decline was observed in HAV infection rates, fulminant hepatitis, and liver transplantation. This study assessed current viral circulation and estimated protective antibody persistence 4 years after vaccination.

METHODS

Prevalence of prevaccination anti-HAV antibodies in 12-month-old children was evaluated as an indirect estimation of viral circulation (Group A). Seroprevalence was also measured in 5-year-old children who received 1 dose of HAV vaccine at 1 year of age (Group B). Blood samples were tested for immunoglobulin (Ig)G anti-HAV antibodies (seroprotection = ≥10 mIU/mL). All Group A-positive samples were tested for IgM anti-HAV antibodies to identify recent infections. Logistic regression analysis was done to evaluate associations between demographic and socioeconomic variables and seroprotection.

RESULTS

Of 433 children from Group A, 29.5% (95% confidence interval [CI], 25.2-33.8) were positive for IgG anti-HAV antibodies with a geometric mean concentration (GMC) of 6.17 mIU/mL (95% CI, 5.33-7.15 mIU/mL); all IgM anti-HAV were negative. From 1139 in Group B, 93% (95% CI, 91.7-94.6) maintained seroprotection with a GMC of 97.96 mIU/mL (95% CI, 89.21-107.57 mIU/mL). Kindergarten attendance was associated with seroprotection in Group B (odds ratio [OR], 2.0; 95% CI, 1.26-3.3). In contrast, high maternal educational level was associated with a lack of seroprotection in this group (OR, .26; 95% CI, .09-.8).

CONCLUSIONS

Single-dose, universal hepatitis A immunization in infants resulted in low HAV circulation and persistent immunologic protection up to 4 years in Argentina. Variables associated with presence or absence of seroprotection in vaccinated children could be related to differences in hygiene habits in settings with residual viral circulation.

Seroprevalence of hepatitis A in Iranian adolescents: is it time to introduce a vaccine?

Universal vaccination of children for hepatitis A virus (HAV) has emerged as a cost-effective strategy to prevent this infection in regions with high incidence of symptomatic disease. Age-specific seroprevalence surveys are practical and reliable methods to estimate the rate of susceptibility in populations, and to help the implementation of vaccination policies. We surveyed the age-specific HAV seroprevalence in a nationally representative sample of Iranian adolescent students aged 10-18 years. Serum samples (n = 2494) were tested by enzyme immunoassay for total anti-HAV antibody. The overall rate of HAV seropositivity was 64% [95% confidence interval (CI), 62-66), which increased sharply from 14·8% (95% CI 7-23) at age 10 years to 72·9% (95% CI 68-78) at age 13 years, without a significant increase up to age 18 years. No significant difference in HAV seroprevalence was observed between males and females (63% vs. 65·1%), or urban and rural areas (63·4% vs. 65·2%); the seropositivity rate was similar in four different socioeconomic regions of Iran. We conclude that the seroconversion rate of HAV is high in Iranian adolescents and therefore mass vaccination of children may be necessary and should be considered by national health authorities.

Evidence of hepatitis A virus person-to-person transmission in household outbreaks

The person-to-person transmission of the hepatitis A virus primarily occurs in enclosed spaces, particularly in the presence of inadequate hygiene conditions and a high proportion of susceptible individuals. Thus, intimate family contact stands out as a risk factor for HAV infection dissemination. The present study aimed to evaluate the occurrence of household HAV transmission. Blood samples were collected from patients with hepatitis A (index cases) and their family members (contacts) that were referred to an ambulatory care clinic specializing in viral hepatitis. A total of 97 samples were collected from 30 families with a confirmed hepatitis A case (index case). Serological and molecular techniques for the diagnosis of hepatitis A were conducted on all samples. HAV infection (anti-HAV IgM + and/or HAV RNA +) was detected in 34.3% (23/67) of the contacts; 34.3% (23/67) of the contacts were immune to HAV, and 31.4% (21/67) were susceptible. In the household contacts, HAV immunity was significantly associated with older age; susceptibility to infection and HAV infection were associated with younger age. Household outbreaks were detected in 16/30 families studied. Co-circulation of subgenotypes IA and IB was found in the household outbreaks, and person-to-person transmission was evidenced in six of the household outbreaks, with 100% homology between the index case and contact strains. The results demonstrated the relevance of HAV household transmission, reaffirming the need for hepatitis A vaccine administration in susceptible contacts and effective infection control procedures to prevent the extension of household outbreaks.

Evidence of hepatitis A virus circulation in central Argentina: seroprevalence and environmental surveillance

BACKGROUND

Hepatitis A virus (HAV) has shown intermediate endemicity in Argentina, but notification of clinical cases has decreased since the introduction of the vaccine in 2005.

OBJECTIVES

In order to get insight into the local circulation of this virus after four years of the official introduction of the vaccine, the aims of this study were to provide information on HAV immune status of the adult population of Córdoba city and to conduct environmental surveillance of HAV in sewage and river samples in the same region.

STUDY DESIGN

The prevalence of anti-HAV was determined by EIA in 416 samples of people (without prior vaccination) from Córdoba city (2009-2010). Spline regression models were estimated under generalized additive models. Environmental surveillance was conducted in river and sewage samples collected in the same period. Viral detection was performed by RT-Nested PCR of the 5'UTR.

RESULTS

In Córdoba, the global prevalence of anti-HAV was 73.5%. It increased with age (p<0.0001) and it was associated with the low-income population (OR: 1.14; 95% CI 1.05-1.25). This prevalence decreased in younger age groups, especially in the high-income population. Environmental monitoring revealed the presence of HAV (IA) in 20.8% and 16.1% of wastewater and river samples, respectively.

CONCLUSIONS

As a consequence of a decrease in HAV circulation due to improvements in immunization, socio-economic and hygienic conditions, young adults are becoming increasingly susceptible to HAV infections. Environmental monitoring demonstrated that HAV circulates in the local population; therefore, health care systems should consider the implementation of preventive measures for susceptible adults in order to reduce the risk of HAV infection.