scholarly journals Assessing countermeasures during a hepatitis A virus outbreak among men who have sex with men

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Ryohei Saito ◽  
Akifumi Imamura ◽  
Hiroshi Nishiura
Keyword(s):  
Mathematical Model ◽  
Situation Awareness ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Reproduction Number ◽  
Risky Behaviors ◽  
Extrinsic Factors ◽  
Environmental Transmission ◽  
Sex With Men ◽  
Epidemic Risk

Abstract Background A hepatitis A epidemic occurred among men who have sex with men (MSM) in Japan in 2017–2018. In this study, we employ a parsimonious mathematical model to epidemiologically investigate the dynamics of infection, aiming to evaluate the effectiveness of campaign-based interventions among MSM to raise awareness of the situation. Methods A mathematical model describing a mixture of human-to-human transmission and environmental transmission was fitted to surveillance data. Taking seasonally varying environmental transmission into account, we estimated the reproduction number of hepatitis A virus during the course of epidemic, and, especially, the abrupt decline in this reproduction number following campaign-based interventions. Results The reproduction number prior to the countermeasures ranged from 2.6 to 3.1 and then began to decrease following campaign-based interventions. After the first countermeasure, the reproduction number decreased, but the epidemic remained supercritical (i.e., Rt > 1). The value of Rt dropped well below one following the second countermeasure, which used web articles to widely disseminate information about the epidemic risk. Conclusions Although the effective reproduction number, Rt, changes because of both intrinsic and extrinsic factors, the timing of the examined countermeasures against hepatitis A in the MSM population was consistent with the abrupt declines observed in Rt. Even without vaccination, the epidemic was brought under control, and risky behaviors may have been changed by the increase in situation awareness reached through web articles.

scholarly journals Estimating the critical immunity threshold for preventing hepatitis A outbreaks in men who have sex with men

2015 ◽  
Vol 144 (7) ◽  
pp. 1528-1537 ◽  
Author(s):  
D. G. REGAN ◽  
J. G. WOOD ◽  
C. BENEVENT ◽  
H. ALI ◽  
L. WATCHIRS SMITH ◽  
...  
Keyword(s):  
High Risk ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Reproduction Number ◽  
Vaccine Coverage ◽  
Risk Groups ◽  
Developed Countries ◽  
Population Immunity ◽  
Sex With Men ◽  
The Basic Reproduction Number

SUMMARYSeveral outbreaks of hepatitis A in men who have sex with men (MSM) were reported in the 1980s and 1990s in Australia and other countries. An effective hepatitis A virus (HAV) vaccine has been available in Australia since 1994 and is recommended for high-risk groups including MSM. No outbreaks of hepatitis A in Australian MSM have been reported since 1996. In this study, we aimed to estimate HAV transmissibility in MSM populations in order to inform targets for vaccine coverage in such populations. We used mathematical models of HAV transmission in a MSM population to estimate the basic reproduction number (R0) and the probability of an HAV epidemic occurring as a function of the immune proportion. We estimated a plausible range forR0of 1·71–3·67 for HAV in MSM and that sustained epidemics cannot occur once the proportion immune to HAV is greater than ~70%. To our knowledge this is the first estimate ofR0and the critical population immunity threshold for HAV transmission in MSM. As HAV is no longer endemic in Australia or in most other developed countries, vaccination is the only means of maintaining population immunity >70%. Our findings provide impetus to promote HAV vaccination in high-risk groups such as MSM.

scholarly journals Evidence for positive selection of hepatitis A virus antigenic variants in vaccinated men-having-sex-with men patients: Implications for immunization policies

EBioMedicine ◽  
2019 ◽  
Vol 39 ◽  
pp. 348-357 ◽  
Author(s):  
Aurora Sabrià ◽  
Josep Gregori ◽  
Damir Garcia-Cehic ◽  
Susana Guix ◽  
Tomàs Pumarola ◽  
...  
Keyword(s):  
Positive Selection ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Sex With Men ◽  
Selection Of

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

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0256818
Author(s):  
Lisie Souza Castro ◽  
Grazielli Rocha de Rezende ◽  
Fernanda Rodas Pires Fernandes ◽  
Larissa Melo Bandeira ◽  
Gabriela Alves Cesar ◽  
...  
Keyword(s):  
Risk Factors ◽  
Sexual Behaviors ◽  
Household Income ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Transgender Women ◽  
Antibody Testing ◽  
Cross Sectional ◽  
Monthly Household Income ◽  
Sex With Men

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.

Clinical and virological features of acute hepatitis A during an ongoing outbreak among men who have sex with men in the North of France

2018 ◽  
Vol 95 (1) ◽  
pp. 75-77 ◽  
Author(s):  
Anne Boucher ◽  
Agnes Meybeck ◽  
Kazali Alidjinou ◽  
Thomas Huleux ◽  
Nathalie Viget ◽  
...  
Keyword(s):  
Acute Hepatitis ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Healthcare Providers ◽  
High Rate ◽  
Missed Opportunities ◽  
The North ◽  
Acute Hepatitis A ◽  
History Of ◽  
Sex With Men

ObjectivesSince February 2017, an increase of acute hepatitis A (AHA) cases has been notified in North of France. We aimed to report clinical and virological features of 49 cases treated in three hospitals in Lille European Metropolis (LEM).MethodsAll adult patients treated for AHA in 3 LEM hospitals between 20 February and 5 July 2017 were included. Demographic characteristics, exposure risk factors to hepatitis A virus (HAV), AHA manifestations and concomitant sexually transmitted infections (STI) were retrospectively recorded.ResultsForty-nine cases of AHA were diagnosed among which 34 (69%) were hospitalised. Severe AHA occurred in 7 (14%) patients. The median age of cases was 36 years. All cases except 1 were men and 32 (65%) were identified as men having sex with men (MSM). Eleven (23%) patients were HIV-infected, 5 were under HIV pre-exposure prophylaxis (PrEP), 6 had a history of HIV postexposure prophylaxis and 19 had a history of at least one STI. Only three patients had received HAV vaccine. Proportion of patients tested for syphilis, chlamydial and gonococcal infections was 75% (18/24) in those seen by sexual health specialists and 21% (6/29) in those seen by other specialists. At least one concomitant STI was diagnosed in 13 out of 24 tested patients (54%). RT-PCR sequencing was available for 38 cases and confirmed co-circulation of 3 different strains of subgenotype IA (VRD 521 2016: n=24, RIVM-HAV16-090: n=13, V16-25801: n=1), already identified in several European countries.ConclusionsWe are facing an outbreak of AHA among MSM in the North of France with a high rate of hospitalisation. Analysis of cases highlighted missed opportunities of vaccination and lack of concomitant STI screening. Awareness among healthcare providers and MSM should be increased and HAV vaccination promoted.

scholarly journals Susceptibility to Hepatitis A Virus Infection in the United States, 2007–2016

2020 ◽  
Vol 71 (10) ◽  
pp. e571-e579 ◽  
Author(s):  
Shaoman Yin ◽  
Laurie Barker ◽  
Kathleen N Ly ◽  
Greta Kilmer ◽  
Monique A Foster ◽  
...  
Keyword(s):  
United States ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Risk Groups ◽  
The United States ◽  
Poverty Level ◽  
Health And Nutrition ◽  
National Immunization ◽  
Vaccination Recommendations ◽  
Sex With Men

Abstract Background Despite national immunization efforts, including universal childhood hepatitis A (HepA) vaccination recommendations in 2006, hepatitis A virus (HAV)–associated outbreaks have increased in the United States. Unvaccinated or previously uninfected persons are susceptible to HAV infection, yet the susceptibility in the US population is not well known. Methods Using National Health and Nutrition Examination Survey 2007–2016 data, we estimated HAV susceptibility prevalence (total HAV antibody negative) among persons aged ≥2 years. Among US-born adults aged ≥20 years, we examined prevalence, predictors, and age-adjusted trends of HAV susceptibility by sociodemographic characteristics. We assessed HAV susceptibility and self-reported nonvaccination to HepA among risk groups and the “immunization cohort” (those born in or after 2004). Results Among US-born adults aged ≥20 years, HAV susceptibility prevalence was 74.1% (95% confidence interval, 72.9–75.3%) during 2007–2016. Predictors of HAV susceptibility were age group 30–49 years, non-Hispanic white/black, 130% above the poverty level, and no health insurance. Prevalences of HAV susceptibility and nonvaccination to HepA, respectively, were 72.9% and 73.1% among persons who reported injection drug use, 67.5% and 65.2% among men who had sex with men, 55.2% and 75.1% among persons with hepatitis B or hepatitis C, and 22.6% and 25.9% among the immunization cohort. Susceptibility and nonvaccination decreased over time among the immunization cohort but remained stable among risk groups. Conclusions During 2007–2016, approximately three-fourths of US-born adults remained HAV susceptible. Enhanced vaccination efforts are critically needed, particularly targeting adults at highest risk for HAV infection, to mitigate the current outbreaks.

scholarly journals Bayesian modelling of a hepatitis A outbreak in men who have sex with men in Sydney, Australia, 1991/1992

2019 ◽  
Vol 147 ◽  
Author(s):  
X.-S. Zhang ◽  
A. Charlett
Keyword(s):  
Least Squares ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Accurate Estimation ◽  
Model Parameters ◽  
Posterior Distributions ◽  
Bayesian Modelling ◽  
Distributed Parameters ◽  
Sex With Men ◽  
Sydney Australia

Abstract To control hepatitis A spread by vaccination, accurate estimation of transmissibility is vital. Regan et al. (2016) proposed a model of hepatitis A virus (HAV) transmission and used least squares to calibrate model to the 1991/1992 HAV outbreak in men who have sex with men (MSM) in Sydney, Australia. Based on the estimate of R0, they obtained the critical immunity of 70% and showed that when the proportion immune <70%, there is a definite chance for outbreaks to take place. The immunity level from previous surveys ranges from 32% to 64% after 1996 while no outbreaks in Australian MSMs have been reported since 1996. Further noticing the ill-distributed parameters, we argue that their estimate of R0 is not accurate. In this study, we revisited their model by Bayesian inference, which has privilege over least squares. We obtained the appropriate posterior distributions of parameters and the estimate of R0 ranges from 1.38 to 2.89, indicating a critical immunity of 65%. The reduction in critical immunity and outbreak probabilities predicts the absence of outbreaks in Australian MSMs since 1996. Our study shows the importance of using appropriate methods to provide reliable and accurate estimates of the model parameters especially the transmissibility.

scholarly journals Outbreak of Hepatitis A Virus Infection among Men Who Have Sex with Men

2000 ◽  
Vol 74 (9) ◽  
pp. 716-719 ◽  
Author(s):  
Akiko TAKECHI ◽  
Shuji HATAKEYAMA ◽  
Tetsuya KASHIYAMA ◽  
Tomohiko KOIBUCHI
Keyword(s):  
Virus Infection ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Sex With Men

scholarly journals Investigating the Role of Environmental Transmission in COVID-19 Dynamics: A Mathematical Model Based Study

2020 ◽  
Author(s):  
Ibrahim M. ELmojtaba ◽  
Fatma Al-Musalhi ◽  
Asma Al-Ghassani ◽  
Nasser Al-Salti
Keyword(s):  
Mathematical Model ◽  
Disease Transmission ◽  
Reproduction Number ◽  
Equilibrium Points ◽  
Transmission Dynamics ◽  
Model Parameters ◽  
Environmental Transmission ◽  
Estimated Parameters ◽  
Existence And Stability

Abstract A mathematical model with environmental transmission has been proposed and analyzed to investigate its role in the transmission dynamics of the ongoing COVID-19 outbreak. Two expressions for the basic reproduction number R0 have been analytically derived using the next generation matrix method. The two expressions composed of a combination of two terms related to human to human and environment to human transmissions. The value of R0 has been calculated using estimated parameters corresponding to two datasets. Sensitivity analysis of the reproduction number to the corresponding model parameters has been carried out. Existence and stability analysis of disease free and endemic equilibrium points have been presented in relation with the obtained expressions of R0. Numerical simulations to demonstrate the effect of some model parameters related to environmental transmission on the disease transmission dynamics have been carried out and the results have been demonstrated graphically.

High prevalence of anti-hepatitis A IgG in a cohort of UK HIV-negative men who have sex with men: implications for local hepatitis A vaccine policy

2018 ◽  
Vol 29 (10) ◽  
pp. 1007-1010 ◽  
Author(s):  
A Bhagey ◽  
K Foster ◽  
S Ralph ◽  
A Wardropper ◽  
C White ◽  
...  
Keyword(s):  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Antibody Test ◽  
Universal Vaccination ◽  
Vaccine Uptake ◽  
Electronic Patient Records ◽  
Previous Infection ◽  
Risk Patients ◽  
Sex With Men ◽  
Hiv Negative

BASHH guidelines recommend that ‘the hepatitis A virus total antibody test can be offered to at-risk patients whose immune status is unknown … depending on local funding arrangements’. We sought to measure the local prevalence of anti-hepatitis A (HAV) IgG in HIV-negative men who have sex with men (MSM), to inform the utility of pre-vaccination screening. We assessed the prevalence of anti-HAV IgG in HIV-negative MSM who attended sexual health services in County Durham and Darlington, UK, from March to August 2017. Data were extracted from electronic patient records and analysed in Excel. Our study was granted local Caldicott approval. Seventy four per cent of 244 HIV-negative MSM who attended for review were screened. Anti-HAV IgG was detected in 42% who did not report definite previous infection or vaccination; not detected in 57.4%; and was equivocal in 0.6%. Vaccine was administered to 48% of eligible patients. The estimated financial costs of universal vaccination of MSM (£4235.40) and pre-vaccination screening with vaccination of susceptible patients (£4188.13) are similar. Pre-vaccination screening and vaccination of susceptible patients does not save resources compared to a policy of universal vaccination of MSM in our setting. Universal vaccination of MSM attending genitourinary medicine clinics may improve vaccine uptake.

scholarly journals Hepatitis A outbreak disproportionately affecting men who have sex with men (MSM) in the European Union and European Economic Area, June 2016 to May 2017

2018 ◽  
Vol 23 (33) ◽  
Author(s):  
Patricia Ndumbi ◽  
Gudrun S Freidl ◽  
Christopher J Williams ◽  
Otilia Mårdh ◽  
Carmen Varela ◽  
...  
Keyword(s):  
European Union ◽  
Sexual Behaviour ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
European Economic Area ◽  
The European Union ◽  
Case Definitions ◽  
European Economic ◽  
Economic Area ◽  
Sex With Men

Between 1 June 2016 and 31 May 2017, 17 European Union (EU) and European Economic Area countries reported 4,096 cases associated with a multi-country hepatitis A (HA) outbreak. Molecular analysis identified three co-circulating hepatitis A virus (HAV) strains of genotype IA: VRD_521_2016, V16–25801 and RIVM-HAV16–090. We categorised cases as confirmed, probable or possible, according to the EU outbreak case definitions. Confirmed cases were infected with one of the three outbreak strains. We investigated case characteristics and strain-specific risk factors for transmission. A total of 1,400 (34%) cases were confirmed; VRD_521_2016 and RIVM-HAV16–090 accounted for 92% of these. Among confirmed cases with available epidemiological data, 92% (361/393) were unvaccinated, 43% (83/195) travelled to Spain during the incubation period and 84% (565/676) identified as men who have sex with men (MSM). Results depict an HA outbreak of multiple HAV strains, within a cross-European population, that was particularly driven by transmission between non-immune MSM engaging in high-risk sexual behaviour. The most effective preventive measure to curb this outbreak is HAV vaccination of MSM, supplemented by primary prevention campaigns that target the MSM population and promote protective sexual behaviour.

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