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Historically, antibody reactivity to pathogens and vaccine antigens has been evaluated using serological measurements of antigen-specific antibodies. However, it is difficult to evaluate all antibodies that contribute to various functions in a single assay, such as the measurement of the neutralizing antibody titer. Bulk antibody repertoire analysis using next-generation sequencing is a comprehensive method for analyzing the overall antibody response; however, it is unreliable for estimating antigen-specific antibodies due to individual variation. To address this issue, we propose a method to subtract the background signal from the repertoire of data of interest. In this study, we analyzed changes in antibody diversity and inferred the heavy-chain complementarity-determining region 3 (CDRH3) sequences of antibody clones that were selected upon influenza virus infection in a mouse model using bulk repertoire analysis. A decrease in the diversity of the antibody repertoire was observed upon viral infection, along with an increase in neutralizing antibody titers. Using kernel density estimation of sequences in a high-dimensional sequence space with background signal subtraction, we identified several clusters of CDRH3 sequences induced upon influenza virus infection. Most of these repertoires were detected more frequently in infected mice than in uninfected control mice, suggesting that infection-specific antibody sequences can be extracted using this method. Such an accurate extraction of antigen- or infection-specific repertoire information will be a useful tool for vaccine evaluation in the future. IMPORTANCE: As specific interactions between antigens and cell-surface antibodies trigger the proliferation of B-cell clones, the frequency of each antibody sequence in the samples reflects the size of each clonal population. Nevertheless, it is extremely difficult to extract antigen-specific antibody sequences from the comprehensive bulk antibody sequences obtained from blood samples due to repertoire bias influenced by exposure to dietary antigens and other infectious agents. This issue can be addressed by subtracting the background noise from the post-immunization or post-infection repertoire data. In the present study, we propose a method to quantify repertoire data from comprehensive repertoire data. This method allowed subtraction of the background repertoire, resulting in more accurate extraction of expanded antibody repertoires upon influenza virus infection. This accurate extraction of antigen- or infection-specific repertoire information is a useful tool for vaccine evaluation.
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Anticuerpos Antivirales , Infecciones por Orthomyxoviridae , Orthomyxoviridae , Animales , Ratones , Anticuerpos Neutralizantes/sangre , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/inmunología , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/química , Anticuerpos Antivirales/inmunología , Linfocitos B/citología , Linfocitos B/inmunología , Células Clonales/citología , Células Clonales/inmunología , Regiones Determinantes de Complementariedad/inmunología , Vacunas contra la Influenza/inmunología , Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/sangre , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/virologíaRESUMEN
Understanding host behavioral change in response to epidemics is important to forecast the disease dynamics. To predict the behavioral change relevant to the epidemic situation (e.g., the number of reported cases), we need to know the epidemic situation at the moment of decision, which is difficult to identify from the records of actually performed human mobility. In this study, the largest travel accommodation reservation data covering half of the existed accommodations in Japan was analyzed to observe decision-making timings and how it responded to the changing epidemic situation during Japan's Coronavirus Disease 2019 until February 2023. To this end, we measured mobility avoidance index proposed in Ito et al., 2022 to indicate people's decision of mobility avoidance and quantified it using the time-series of the accommodation booking/cancellation data. We observed matches of the peak dates of the mobility avoidance and the number of reported cases, and mobility avoidance changed proportional to the logarithmic number of reported cases. We also found that the slope of mobility avoidance against the change of the logarithmic number of reported cases were similar among the epidemic waves, while the intercept of that was much reduced as the first epidemic wave passed by. People measure the intensity of epidemic by logarithm of the number of reported cases. The sensitivity of their response is established during the first wave and the people's response became weakened after the first experience, as if the number of reported cases were multiplied by a constant small factor.
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COVID-19 , Epidemias , Humanos , COVID-19/epidemiología , SARS-CoV-2 , Japón/epidemiología , PredicciónRESUMEN
BACKGROUND: While airport screening measures for COVID-19 infected passengers at international airports worldwide have been greatly relaxed, observational studies evaluating fever screening alone at airports remain scarce. The purpose of this study is to retrospectively assess the effectiveness of fever screening at airports in preventing the influx of COVID-19 infected persons. METHODS: We conducted a retrospective epidemiological analysis of fever screening implemented at 9 airports in Okinawa Prefecture from May 2020 to March 2022. The number of passengers covered during the same period was 9,003,616 arriving at 9 airports in Okinawa Prefecture and 5,712,983 departing passengers at Naha Airport. The capture rate was defined as the proportion of reported COVID-19 cases who would have passed through airport screening to the number of suspected cases through fever screening at the airport, and this calculation used passengers arriving at Naha Airport and surveillance data collected by Okinawa Prefecture between May 2020 and March 2021. RESULTS: From May 2020 to March 2021, 4.09 million people were reported to pass through airports in Okinawa. During the same period, at least 122 people with COVID-19 infection arrived at the airports in Okinawa, but only a 10 suspected cases were detected; therefore, the capture rate is estimated to be up to 8.2% (95% CI: 4.00-14.56%). Our result of a fever screening rate is 0.0002% (95%CI: 0.0003-0.0006%) (10 suspected cases /2,971,198 arriving passengers). The refusal rate of passengers detected by thermography who did not respond to temperature measurements was 0.70% (95% CI: 0.19-1.78%) (4 passengers/572 passengers). CONCLUSIONS: This study revealed that airport screening based on thermography alone missed over 90% of COVID-19 infected cases, indicating that thermography screening may be ineffective as a border control measure. The fact that only 10 febrile cases were detected after screening approximately 3 million passengers suggests the need to introduce measures targeting asymptomatic infections, especially with long incubation periods. Therefore, other countermeasures, e.g. preboarding RT-PCR testing, are highly recommended during an epidemic satisfying World Health Organization (WHO) Public Health Emergency of International Concern (PHEIC) criteria with pathogen characteristics similar or exceeding SARS-CoV-2, especially when traveling to rural cities with limited medical resources.
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Aeropuertos , COVID-19 , Fiebre , Tamizaje Masivo , SARS-CoV-2 , Humanos , COVID-19/diagnóstico , COVID-19/epidemiología , Japón/epidemiología , Fiebre/diagnóstico , Fiebre/epidemiología , Fiebre/virología , Estudios Retrospectivos , Tamizaje Masivo/métodos , SARS-CoV-2/aislamiento & purificación , Viaje , Masculino , Adulto , FemeninoRESUMEN
Understanding the impact of vaccination in a host population is essential to control infectious diseases. However, the impact of bait vaccination against wildlife diseases is difficult to evaluate. The vaccination history of host animals is generally not observable in wildlife, and it is difficult to distinguish immunity by vaccination from that caused by disease infection. For these reasons, the impact of bait vaccination against classical swine fever (CSF) in wild boar inhabiting Japan has not been evaluated accurately. In this study, we aimed to estimate the impact of the bait vaccination campaign by modelling the dynamics of CSF and the vaccination process among a Japanese wild boar population. The model was designed to estimate the impact of bait vaccination despite lack of data regarding the demography and movement of wild boar. Using our model, we solved the theoretical relationship between the impact of vaccination, the time-series change in the proportion of infected wild boar, and that of immunised wild boar. Using this derived relationship, the increase in antibody prevalence against CSF because of vaccine campaigns in 2019 was estimated to be 12.1 percentage points (95% confidence interval: 7.8-16.5). Referring to previous reports on the basic reproduction number (R0) of CSF in wild boar living outside Japan, the amount of vaccine distribution required for CSF elimination by reducing the effective reproduction number under unity was also estimated. An approximate 1.6 (when R0 = 1.5, target vaccination coverage is 33.3% of total population) to 2.9 (when R0 = 2.5, target vaccination coverage is 60.0% of total population) times larger amount of vaccine distribution would be required than the total amount of vaccine distribution in four vaccination campaigns in 2019.
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Peste Porcina Clásica , Vacunas Virales , Animales , Animales Salvajes , Peste Porcina Clásica/epidemiología , Peste Porcina Clásica/prevención & control , Japón/epidemiología , Sus scrofa , Porcinos , Vacunación/veterinariaRESUMEN
BACKGROUND: Herpes simplex virus type 1 (HSV-1) epidemiology in Asia was characterized by assessing seroprevalence levels and extent to which HSV-1 is isolated from clinically diagnosed genital ulcer disease (GUD) and genital herpes. METHODS: HSV-1 reports in Asia were systematically reviewed and synthesized, following PRISMA guidelines. Random-effects meta-analyses estimated pooled mean seroprevalence and proportion of HSV-1 detection in GUD and genital herpes. Random-effects meta-regressions identified predictors of seroprevalence and sources of between-study heterogeneity. RESULTS: Forty-nine relevant publications were identified. Fifty-four overall seroprevalence measures (182 stratified measures), and 8 and 24 proportions of HSV-1 detection in GUD and in genital herpes, respectively, were extracted. The pooled mean seroprevalence was 50.0% (n = 26; 95% confidence interval [CI], 41.3%-58.7%) for children and 76.5% (n = 151; 73.3%-79.6%) for adults. By age group, the pooled mean was lowest at 55.5% (n = 37; 95% CI, 47.5%-63.4%) in individuals aged <20 years, followed by 67.9% (n = 48; 62.4%-73.3%) in those aged 20-39 and 87.5% (n = 44; 83.4%-91.1%) in those aged ≥40 years. In meta-regression, age was the major predictor of seroprevalence. The mean proportion of HSV-1 detection was 5.6% (n = 8; 95% CI, 0.8%-13.6%) in GUD and 18.8% (n = 24; 12.0%-26.7%) in genital herpes. CONCLUSIONS: HSV-1 epidemiology is transitioning in Asia. HSV-1 is probably playing a significant role as a sexually transmitted infection, explaining one-fifth of genital herpes cases. There is a need for expanded seroprevalence monitoring and GUD/genital herpes etiological surveillance.
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Herpes Simple/epidemiología , Herpesvirus Humano 1 , Anticuerpos Antivirales/sangre , Asia/epidemiología , Herpes Simple/virología , Humanos , Estudios SeroepidemiológicosRESUMEN
Cancer cells can invade as a population in various cancer tissues. This phenomenon is called collective invasion, which is associated with the metastatic potential and prognosis of cancer patients. The collectiveness of cancer cells is necessary for collective invasion. However, the mechanism underlying the generation of collectiveness by cancer cells is not well known. In this study, the phenomenon of contact following, where neighboring cells move in the same direction via intercellular adhesion, was investigated. An experimental system was created to observe the two-dimensional invasion using a collagen gel overlay to study contact following in collective invasion. The role of integrin-ß1, one of the major extracellular matrix (ECM) receptors, in contact following was examined through the experimental system. Integrin-ß1 was localized to the intercellular site in squamous carcinoma cells. Moreover, the intercellular adhesion and contact following were suppressed by treatment of an integrin-ß1 inhibitory antibody. ECM proteins such as laminin-332 and type-XVII collagen were also localized to the intercellular site and critical for contact following. Collectively, it was demonstrated that the activity of integrin-ß1 and expression of ECM proteins in the intercellular site promote contact following in the collective invasion of a cancer cell population.
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Autoantígenos/metabolismo , Carcinoma de Células Escamosas/metabolismo , Moléculas de Adhesión Celular/metabolismo , Integrina beta1/metabolismo , Colágenos no Fibrilares/metabolismo , Neoplasias Cutáneas/metabolismo , Autoantígenos/biosíntesis , Carcinoma de Células Escamosas/patología , Adhesión Celular , Moléculas de Adhesión Celular/biosíntesis , Humanos , Integrina beta1/biosíntesis , Colágenos no Fibrilares/biosíntesis , Neoplasias Cutáneas/patología , Células Tumorales Cultivadas , Kalinina , Colágeno Tipo XVIIRESUMEN
OBJECTIVES: To explore whether existence of long-lasting partial immunity against reinfection with Chlamydia trachomatis is necessary to explain C. trachomatis prevalence patterns by age and sexual risk, and to provide a plausible estimate for the effect size, defined here as a reduction in susceptibility to reinfection. METHODS: A population-based mathematical model was constructed to describe C. trachomatis natural history and transmission dynamics by age and sexual risk. The model was parameterised using natural history, and epidemiological and sexual behaviour data, and applied for UK and US data. Sensitivity analyses were conducted to assess the robustness of predictions to variations in model structure and to examine the impact of alternative assumptions for the mechanism underlying partial immunity. RESULTS: Partial immunity against reinfection was found necessary to explain observed C. trachomatis prevalence patterns by age and sexual risk. The reduction in susceptibility to reinfection was estimated at 93% using UK data (95% uncertainty interval (UI)=88%-97%) and at 67% using US data (95% UI=24%-88%). The model-structure sensitivity analyses affirmed model predictions. The immunity-mechanism sensitivity analyses suggested a mechanism of susceptibility reduction against reinfection or a mechanism of infectious-period duration reduction upon reinfection. CONCLUSIONS: A strong long-lasting partial immunity against C. trachomatis reinfection should be present to explain observed prevalence patterns. The mechanism of immunity could be either a reduction in susceptibility to reinfection or a reduction in duration of infection on reinfection. C. trachomatis infection appears to naturally elicit a strong long-lasting immune response, supporting the concept of vaccine development.
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Factores de Edad , Infecciones por Chlamydia/epidemiología , Infecciones por Chlamydia/inmunología , Modelos Teóricos , Conducta Sexual , Adolescente , Adulto , Infecciones por Chlamydia/transmisión , Chlamydia trachomatis , Susceptibilidad a Enfermedades , Femenino , Humanos , Masculino , Persona de Mediana Edad , Población , Prevalencia , Recurrencia , Factores de Riesgo , Reino Unido/epidemiología , Estados Unidos/epidemiología , Adulto JovenRESUMEN
OBJECTIVES: To investigate whether observational studies of HIV and herpes simplex virus type 2 (HSV-2) infections have the capacity to assess the HIV/HSV-2 epidemiological synergy. METHODS: An individual-based Monte Carlo model was used to simulate HIV/HSV-2 epidemics in two scenarios: no HIV/HSV-2 biological interaction and HSV-2 seropositivity enhancing HIV acquisition. Cross-sectional observational studies were simulated by sampling individuals from the population to assess resulting crude and adjusted ORs of the HIV/HSV-2 association. Meta-analyses were conducted to estimate the pooled mean ORs. Impact of under-reporting of sexual behaviour and miscapture of high-risk individuals was assessed through sensitivity analyses. RESULTS: Assuming no HIV/HSV-2 biological interaction, the crude HIV/HSV-2 OR ranged between 1.38 and 9.93, with a pooled mean of 6.45 (95% CI 5.81 to 7.17). Adjustment for the number of sexual partners over last year, over lifetime and for both partner numbers simultaneously reduced the mean OR to 5.45 (95% CI 4.90 to 6.06), 3.70 (95% CI 3.32 to 4.12) and 3.54 (95% CI 3.17 to 3.94), respectively. Assuming HIV/HSV-2 biological interaction, the crude OR ranged between 3.44 and 9.95, with a pooled mean of 8.05 (95% CI 7.14 to 9.07). The adjustments reduced the mean OR to 7.00 (95% CI 6.21 to 7.90), 3.76 (95% CI 3.32 to 4.25) and 3.68 (95% CI 3.25 to 4.17), respectively. Under-reporting of partners reduced the confounder-adjustment effects. Miscapture of high-risk individuals considerably lowered the estimated ORs. CONCLUSIONS: It is difficult to control for sexual-behaviour confounding in observational studies. The observed HIV/HSV-2 association appears more consistent with two infections sharing the same mode of transmission, rather than with HSV-2 enhancing HIV acquisition.
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Infecciones por VIH/epidemiología , Herpes Genital/epidemiología , Modelos Estadísticos , Estudios Observacionales como Asunto/normas , Adolescente , Adulto , Anciano , Estudios Transversales , Femenino , VIH/aislamiento & purificación , Infecciones por VIH/transmisión , Infecciones por VIH/virología , Herpes Genital/transmisión , Herpes Genital/virología , Herpes Simple/epidemiología , Herpesvirus Humano 2/aislamiento & purificación , Humanos , Masculino , Persona de Mediana Edad , Método de Montecarlo , Prevalencia , Análisis de Regresión , Reproducibilidad de los Resultados , Factores de Riesgo , Conducta Sexual , Parejas Sexuales , Adulto JovenRESUMEN
The number of person-to-person transmitted norovirus cases (n = 4,712) in school children in Osaka, Japan, during 2016/17 was the largest since 2012/13. Norovirus outbreaks were reported by 101 schools including 53 nursery schools (1,927 cases), 18 kindergartens (1,086 cases) and 30 elementary schools (1,699 cases). The dominant genotype among outbreaks was GII.P16-GII.2 (57.4%; 58/101), followed by GII.P2-GII.2 (8.9%; 9/101) and GII.P7-GII.6 (5.9%; 6/101). GII.4 was not detected despite dominance in previous years.
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Infecciones por Caliciviridae/epidemiología , Infecciones por Caliciviridae/transmisión , Brotes de Enfermedades , Gastroenteritis/virología , Norovirus/genética , Adolescente , Infecciones por Caliciviridae/virología , Niño , Preescolar , Femenino , Gastroenteritis/epidemiología , Humanos , Incidencia , Masculino , Norovirus/clasificación , Vigilancia de la Población , Estaciones del AñoRESUMEN
BACKGROUND: Herpes Simplex Virus Type 2 (HSV-2) is one of the most common sexually transmitted diseases. Although there is still no licensed vaccine for HSV-2, a theoretical investigation of the potential effects of a vaccine is considered important and has recently been conducted by several researchers. Although compartmental mathematical models were considered for each special case in the previous studies, as yet there are few global stability results. RESULTS: In this paper, we formulate a multi-group SVIRI epidemic model for HSV-2, which enables us to consider the effects of vaccination, of waning vaccine immunity, and of infection relapse. Since the number of groups is arbitrary, our model can be applied to various structures such as risk, sex, and age group structures. For our model, we define the basic reproduction number â0 and prove that if â0≤1, then the disease-free equilibrium is globally asymptotically stable, whereas if â0>1, then the endemic equilibrium is so. Based on this global stability result, we estimate â0 for HSV-2 by applying our model to the risk group structure and using US data from 2001 to 2014. Through sensitivity analysis, we find that â0 is approximately in the range of 2-3. Moreover, using the estimated parameters, we discuss the optimal vaccination strategy for the eradication of HSV-2. CONCLUSIONS: Through discussion of the optimal vaccination strategy, we come to the following conclusions. (1) Improving vaccine efficacy is more effective than increasing the number of vaccines. (2) Although the transmission risk in female individuals is higher than that in male individuals, distributing the available vaccines almost equally between female and male individuals is more effective than concentrating them within the female population.
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Herpes Simple/virología , Herpesvirus Humano 2/fisiología , Modelos Biológicos , Susceptibilidad a Enfermedades , Femenino , Herpes Simple/epidemiología , Humanos , Masculino , Prevalencia , Recurrencia , Conducta Sexual , VacunaciónRESUMEN
OBJECTIVE: To develop an analytical understanding of non-cohabiting sex partnering in sub-Saharan Africa (SSA) using nationally representative sexual behaviour data. METHOD: A non-homogenous Poisson stochastic process model was used to describe the dynamics of non-cohabiting sex. The model was applied to 25 countries in SSA and was fitted to Demographic and Health Survey data. The country-specific mean values and variances of the distributions of number of non-cohabiting partners were estimated. RESULTS: The model yielded overall robust fits to the empirical distributions stratified by marital status and sex. The median across all country-specific mean values was highest for unmarried men at 0.574 non-cohabiting partners over the last 12â months, followed by that of unmarried women at 0.337, married men at 0.192 and married women at 0.038. The median of variances was highest for unmarried men at 0.127, followed by married men at 0.057, unmarried women at 0.003 and married women at 0.000. The largest variability in mean values across countries was for unmarried men (0.103-1.206), and the largest variability in variances was among unmarried women (0.000-1.994). CONCLUSIONS: Non-cohabiting sex appears to be a random 'opportunistic' phenomenon linked to situations that may facilitate it. The mean values and variances of number of partners in SSA show wide variation by country, marital status and sex. Unmarried individuals have larger mean values than their married counterparts, and men have larger mean values than women. Unmarried individuals appear to play a disproportionate role in driving heterogeneity in sexual networks and possibly epidemiology of sexually transmitted infections.
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Condones/estadística & datos numéricos , Infecciones por VIH/transmisión , Estado Civil/estadística & datos numéricos , Conducta Sexual/estadística & datos numéricos , Parejas Sexuales , Adulto , África del Sur del Sahara/epidemiología , Análisis de Varianza , Femenino , Infecciones por VIH/prevención & control , Infecciones por VIH/psicología , Humanos , Masculino , Matrimonio , Factores de Riesgo , Asunción de Riesgos , Conducta Sexual/psicología , Parejas Sexuales/psicologíaRESUMEN
Introduction: We aimed to investigate the overlapping epidemiologies of human immunodeficiency virus (HIV), herpes simplex virus type 2 (HSV-2), chlamydia, gonorrhea, and syphilis in sexual networks of men who have sex with men (MSM), and to explore to what extent the epidemiology of one sexually transmitted infection (STI) relates to or differs from that of another STI. Methods: An individual-based Monte Carlo simulation model was employed to simulate the concurrent transmission of STIs within diverse sexual networks of MSM. The model simulated sexual partnering, birth, death, and STI transmission within each specific sexual network. The model parameters were chosen based on the current knowledge and understanding of the natural history, transmission, and epidemiology of each considered STI. Associations were measured using the Spearman's rank correlation coefficient (SRCC) and maximal information coefficient (MIC). Results: A total of 500 sexual networks were simulated by varying the mean and variance of the number of partners for both short-term and all partnerships, degree correlation, and clustering coefficient. HSV-2 had the highest current infection prevalence across the simulations, followed by HIV, chlamydia, syphilis, and gonorrhea. Threshold and saturation effects emerged in the relationship between STIs across the simulated networks, and all STIs demonstrated moderate to strong associations. The strongest current infection prevalence association was between HIV and gonorrhea, with an SRCC of 0.84 (95% CI: 0.80-0.87) and an MIC of 0.81 (95% CI: 0.74-0.88). The weakest association was between HSV-2 and syphilis, with an SRCC of 0.54 (95% CI: 0.48-0.59) and an MIC of 0.57 (95% CI, 0.49-0.65). Gonorrhea exhibited the strongest associations with the other STIs while syphilis had the weakest associations. Across the simulated networks, proportions of the population with zero, one, two, three, four, and five concurrent STI infections were 48.6, 37.7, 11.1, 2.4, 0.3, and < 0.1%, respectively. For lifetime exposure to these infections, these proportions were 13.6, 21.0, 22.9, 24.3, 13.4, and 4.8%, respectively. Conclusion: STI epidemiologies demonstrate substantial overlap and associations, alongside nuanced differences that shape a unique pattern for each STI. Gonorrhea exhibits an "intermediate STI epidemiology," reflected by the highest average correlation coefficient with other STIs.
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Chlamydia , Gonorrea , Infecciones por VIH , Minorías Sexuales y de Género , Enfermedades de Transmisión Sexual , Sífilis , Masculino , Humanos , Gonorrea/epidemiología , Gonorrea/complicaciones , Sífilis/epidemiología , Herpesvirus Humano 2 , Homosexualidad Masculina , VIH , Infecciones por VIH/epidemiología , Infecciones por VIH/complicaciones , Enfermedades de Transmisión Sexual/epidemiologíaRESUMEN
BACKGROUND: This study aimed to examine the transmission dynamics of Neisseria gonorrhoeae (NG) in heterosexual sex work networks (HSWNs) and the impact of variation in sexual behavior and interventions on NG epidemiology. METHODS: The study employed an individual-based mathematical model to simulate NG transmission dynamics in sexual networks involving female sex workers (FSWs) and their clients, primarily focusing on the Middle East and North Africa region. A deterministic model was also used to describe NG transmission from clients to their spouses. RESULTS: NG epidemiology in HSWNs displays two distinct patterns. In the common low-partner-number HSWNs, a significant proportion of NG incidence occurs among FSWs, with NG prevalence 13 times higher among FSWs than clients, and three times higher among clients than their spouses. Interventions substantially reduce incidence. Increasing condom use from 10â¯% to 50â¯% lowers NG prevalence among FSWs, clients, and their spouses from 12.2â¯% to 6.4 %, 1.2 % to 0.5 %, and 0.4 % to 0.2 %, respectively. Increasing symptomatic treatment coverage among FSWs from 0â¯% to 100â¯% decreases prevalence from 10.6â¯% to 4.5 %, 0.8 % to 0.4 %, and 0.3 % to 0.1 %, respectively. Increasing asymptomatic treatment coverage among FSWs from 0â¯% to 50â¯% decreases prevalence from 8.2â¯% to 0.4 %, 0.6 % to 0.1 %, and 0.2 % to 0.0 %, respectively, with very low prevalence when coverage exceeds 50â¯%. In high-partner-number HSWNs, prevalence among FSWs saturates at a high level, and the vast majority of incidence occurs among clients and their spouses, with a limited impact of incremental increases in interventions. CONCLUSION: NG epidemiology in HSWNs is typically a "fragile epidemiology" that is responsive to a range of interventions even if the interventions are incremental, partially efficacious, and only applied to FSWs.
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Revealing interactions between ticks and wild animals is vital for gaining insights into the dynamics of tick-borne pathogens in the natural environment. We aimed to elucidate the factors that determine tick infestation in wild animals by investigating ticks on invasive raccoons (Procyon lotor) in Hokkaido, Japan. We first examined the composition, intensity, and seasonal variation of ticks infesting raccoons in six study areas in Hokkaido from March 2022 to August 2023. In one study area, ticks infesting tanukis (raccoon dog, Nyctereutes procyonoides albus) were collected in May to July in both 2022 and 2023, and questing ticks were collected from the vegetation by flagging every other week in the same period. Next, we screened 17 environmental and host variables to determine factors that affect the number of ticks infesting raccoons using generalized linear (mixed) models. From 245 raccoons, we identified a total of 3,917 ticks belonging to eight species of two genera: the most prominent species were Ixodes ovatus (52.9 %), followed by Haemaphysalis megaspinosa (14.4 %), Ixodes tanuki (10.6 %), and Ixodes persulcatus (9.5 %). Ixodes ovatus was also predominant among questing ticks and ticks infesting tanukis. Although I. tanuki was frequently collected from raccoons and tanukis, it was rarely collected in the field. The variables that significantly affected the infestation on raccoons differed by genus, species and developmental stage of the tick. For instance, the infestation of adult I. ovatus was significantly affected by four variables: night-time temperature during nine days before capturing the raccoon, the size of forest area around the capture site, sex of the raccoon, and sampling season. The first two variables were also responsible for the infestation on raccoons of almost all species and stages of ticks. Our study revealed that the number and composition of ticks infesting raccoons can be affected not only by landscape of their habitats but also by weather conditions in several days before capturing.
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High evolvability of influenza virus and the complex nature of its antagonistic interaction with the host immune system make it difficult to predict which strain of virus will become epidemic next and when it will emerge. To investigate the most likely time at which a new successful strain emerges every year in seasonal influenza, we use an individual-based model that takes into account the seasonality in transmission rate and host cross-immunity against a current viral strain due to previous infections with other strains. Our model deals with antigenic evolution of influenza virus that originated by point mutations at amino acid sites that constitute epitope and is driven by host immune response. Under the range of parameters by which influenza virus shows a "trunk" shape in its phylogenetic tree, as is typical in influenza A virus evolution, we find that most successful mutant strains emerge in an early part of the epidemic season, and that the time when the number of infected hosts reaches a maximum tends to be more than one season after viral emergence. This carryover of the epidemic peak timing implies that we can predict the strain that will become dominant in the epidemic in the following year.
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Gripe Humana/virología , Modelos Inmunológicos , Orthomyxoviridae/genética , Variación Antigénica/genética , Número Básico de Reproducción , Epidemias , Evolución Molecular , Humanos , Gripe Humana/epidemiología , Gripe Humana/inmunología , Gripe Humana/transmisión , Modelos Genéticos , Orthomyxoviridae/inmunología , Estaciones del Año , Factores de TiempoRESUMEN
Background: The impact of the COVID-19 vaccination campaign in the US has been hampered by a substantial geographical heterogeneity of the vaccination coverage. Several studies have proposed vaccination hesitancy as a key driver of the vaccination uptake disparities. However, the impact of other important structural determinants such as local disparities in healthcare capacity is virtually unknown. Methods: In this cross-sectional study, we conducted causal inference and geospatial analyses to assess the impact of healthcare capacity on the vaccination coverage disparity in the US. We evaluated the causal relationship between the healthcare system capacity of 2417 US counties and their COVID-19 vaccination rate. We also conducted geospatial analyses using spatial scan statistics to identify areas with low vaccination rates. Findings: We found a causal effect of the constraints in the healthcare capacity of a county and its low-vaccination uptake. Counties with higher constraints in their healthcare capacity were more probable to have COVID-19 vaccination rates ≤50, with 35% higher constraints in low-vaccinated areas (vaccination rates ≤ 50) compared to high-vaccinated areas (vaccination rates > 50). We also found that COVID-19 vaccination in the US exhibits a distinct spatial structure with defined "vaccination coldspots". Interpretation: We found that the healthcare capacity of a county is an important determinant of low vaccine uptake. Our study highlights that even in high-income nations, internal disparities in healthcare capacity play an important role in the health outcomes of the nation. Therefore, strengthening the funding and infrastructure of the healthcare system, particularly in rural underserved areas, should be intensified to help vulnerable communities. Funding: None.
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BACKGROUND: Since the first isolation of rubella virus (RuV) in 1962, comprehensive data regarding the quantitative evaluation of RuV shedding remain unavailable. In this study, we evaluated the shedding of viral RNA and infectious virus in patients with acute RuV infection. STUDY DESIGN: We analyzed 767 specimens, including serum/plasma, peripheral blood mononuclear cells (PBMCs), throat swabs, and urine, obtained from 251 patients with rubella. The viral RNA load and the presence of infectious RuV were determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and virus isolation. RESULTS: Virus excretion peaked 0-2 days after rash onset and decreased over time. The median viral RNA load dropped to an undetectable level on day 3 after rash onset in serum/plasma, day 2 in PBMCs, days 10-13 in throat swabs, and days 6-7 in urine. Infectious virus could be isolated for up to day 2 after rash onset in serum/plasma, day 1 in PBMCs, days 8-9 in throat swabs, and days 4-5 in urine. The minimum viral RNA load that allowed virus isolation was 961 copies/mL in serum/plasma, 784 copies/mL in PBMCs, 650 copies/mL in throat swabs, and 304 copies/mL in urine. A higher viral RNA load indicated a higher likelihood of the presence of infectious virus. CONCLUSION: These findings would contribute to improve algorithms for rubella surveillance and diagnosis. In addition, this study indicates that the results of RT-qPCR enable efficient rubella control by estimating candidate patients excreting infectious virus, which could help prevent viral transmission at an early stage and eliminate rubella ultimately.
Asunto(s)
Exantema , Rubéola (Sarampión Alemán) , Humanos , Virus de la Rubéola/genética , ARN Viral/genética , Leucocitos Mononucleares , Rubéola (Sarampión Alemán)/diagnóstico , Esparcimiento de VirusRESUMEN
Human behavioural changes are poorly understood, and this limitation has been a serious obstacle to epidemic forecasting. It is generally understood that people change their respective behaviours to reduce the risk of infection in response to the status of an epidemic or government interventions. We must first identify the factors that lead to such decision-making to predict these changes. However, due to an absence of a method to observe decision-making for future behaviour, understanding the behavioural responses to disease is limited. Here, we show that accommodation reservation data could reveal the decision-making process that underpins behavioural changes, travel avoidance, for reducing the risk of COVID-19 infections. We found that the motivation to avoid travel with respect to only short-term future behaviours dynamically varied and was associated with the outbreak status and/or the interventions of the government. Our developed method can quantitatively measure and predict a large-scale population's behaviour to determine the future risk of COVID-19 infections. These findings enable us to better understand behavioural changes in response to disease spread, and thus, contribute to the development of reliable long-term forecasting of disease spread.