Drug network identification predicts injecting risk behavior among people who inject drugs on hepatitis C virus treatment in Tayside, Scotland

The risk of Hepatitis C Virus (HCV) acquisition among People Who Inject Drugs (PWID) remains high when injecting risk behavior within networks endures. Several psychosocial factors influence such behavior. Following a drive within Tayside, a geographic region in Scotland, to achieve World Health Organization HCV elimination targets, addressing HCV re-infection risk as a barrier to elimination is critically important. This cross-sectional study seeks to address this barrier to elimination by investigating associations between group identification (one's subjective sense of belonging and connectedness to a social group coupled with a sense of shared goals, beliefs and values with the other members of the group) and injecting risk behavior among PWID on HCV treatment at needle and syringe provision sites in Tayside. Participants completed psychosocial questionnaires between treatment weeks zero and three of treatment. Correlation analyses were undertaken, and significant factors included in multiple linear regression models for injecting risk behavior. Injecting frequency, drug network identification, and family identification, were correlated with injecting risk behavior, and drug network identification had a positive predictive on injecting risk behavior. Identification with a social group, conventionally associated with improved health, may pose health risks in specific contexts. Healthcare providers should consider stratifying individuals with higher group identification with PWID networks for enhanced harm reduction engagement to mitigate transmissible infection risk among PWID. Additionally, psychological interventions to strengthen group identification with networks which impact positively on health behavior should be explored.

Predictors of reinfection with pre-Omicron and Omicron variants of concern among individuals who recovered from COVID-19 in the first year of the pandemic

OBJECTIVES

The predictors of SARS-CoV-2 reinfection are unclear. We examined predictors of reinfection with pre-Omicron and Omicron variants among COVID-19-recovered individuals.

METHODS

Randomly selected COVID-19-recovered patients (N=1004) who donated convalescent plasma during 2020 were interviewed between August 2021-March 2022 regarding COVID-19 vaccination and laboratory-proven reinfection. Sera from 224 (22.3%) participants were tested for anti-S (spike) IgG and neutralizing antibodies.

RESULTS

The participants' median age was 31.1 years (78.6% males). The overall reinfection incidence rate was 12.8%; 2.7% vs. 21.6% for the pre-Omicron (mostly Delta) vs. Omicron variants. Negative associations were found between fever during the first illness and pre-Omicron reinfection: relative risk (RR) 0.29 (95% confidence intervals (CI) 0.09-0.94); high anti-N level at first illness and Omicron reinfection: 0.53 (0.33-0.85), and overall reinfection: 0.56 (0.37-0.84), as well as between subsequent COVID-19 vaccination with the BNT162b2 vaccine and pre-Omicron 0.15 (0.07-0.32), Omicron 0.48 (0.25-0.45), and overall reinfections 0.38 (0.25-0.58). These variables significantly correlated with IgG anti-S follow-up levels. High pre-existing anti-S binding and neutralizing antibody levels against SARS-CoV-2 Wuhan and Alpha strains predicted protection against Omicron reinfections.

CONCLUSIONS

Strong immune responses following first COVID-19 infection and subsequent vaccination with the BNT162b2 vaccine provided cross-protection against reinfections with Delta and Omicron variants.

Determinants and prediction of Chlamydia trachomatis re-testing and re-infection within 1 year among heterosexuals with chlamydia attending a sexual health clinic

Background

Chlamydia trachomatis (chlamydia) is one of the most common sexually transmitted infections (STI) globally, and re-infections are common. Current Australian guidelines recommend re-testing for chlamydia 3 months after treatment to identify possible re-infection. Patient-delivered partner therapy (PDPT) has been proposed to control chlamydia re-infection among heterosexuals. We aimed to identify determinants and the prediction of chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia to identify potential PDPT candidates.

Methods

Our baseline data included 5,806 heterosexuals with chlamydia aged ≥18 years and 2,070 re-tested for chlamydia within 1 year of their chlamydia diagnosis at the Melbourne Sexual Health Center from January 2, 2015, to May 15, 2020. We used routinely collected electronic health record (EHR) variables and machine-learning models to predict chlamydia re-testing and re-infection events. We also used logistic regression to investigate factors associated with chlamydia re-testing and re-infection.

Results

About 2,070 (36%) of 5,806 heterosexuals with chlamydia were re-tested for chlamydia within 1 year. Among those retested, 307 (15%) were re-infected. Multivariable logistic regression analysis showed that older age (≥35 years old), female, living with HIV, being a current sex worker, patient-delivered partner therapy users, and higher numbers of sex partners were associated with an increased chlamydia re-testing within 1 year. Multivariable logistic regression analysis also showed that younger age (18-24 years), male gender, and living with HIV were associated with an increased chlamydia re-infection within 1 year. The XGBoost model was the best model for predicting chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia; however, machine learning approaches and these self-reported answers from clients did not provide a good predictive value (AUC < 60.0%).

Conclusion

The low rate of chlamydia re-testing and high rate of chlamydia re-infection among heterosexuals with chlamydia highlights the need for further interventions. Better targeting of individuals more likely to be re-infected is needed to optimize the provision of PDPT and encourage the test of re-infection at 3 months.

Age-associated SARS-CoV-2 breakthrough infection and changes in immune response in a mouse model

Older individuals are at higher risk of SARS-CoV-2 infection and severe outcomes, but the underlying mechanisms are incompletely understood. In addition, how age modulates SARS-CoV-2 re-infection and vaccine breakthrough infections remain largely unexplored. Here, we investigated age-associated SARS-CoV-2 pathogenesis, immune responses, and the occurrence of re-infection and vaccine breakthrough infection utilizing a wild-type C57BL/6N mouse model. We demonstrated that interferon and adaptive antibody response upon SARS-CoV-2 challenge are significantly impaired in aged mice compared to young mice, which results in more effective virus replications and severe disease manifestations in the respiratory tract. Aged mice also showed increased susceptibility to re-infection due to insufficient immune protection acquired during the primary infection. Importantly, two-dose COVID-19 mRNA vaccination conferred limited adaptive immune response among the aged mice, making them susceptible to SARS-CoV-2 infection. Collectively, our findings call for tailored and optimized treatments and prevention strategies against SARS-CoV-2 among older individuals.

Immune durability and protection against SARS-CoV-2 re-infection in Syrian hamsters

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a pandemic. As immunity to endemic human coronaviruses (i.e. NL63 or OC43) wanes leading to re-infection, it was unknown if SARS-CoV-2 immunity would also decline permitting repeat infections. Recent case reports confirm previously infected individuals can become re-infected; however, re-infection may be due to heterogeneity in the initial infection or the host immune response, or may be the result of infection with a variant strain that escapes pre-existing immunity. To control these variables, we utilized the Syrian hamster model to evaluate the duration of immunity and susceptibility to re-infection with SARS-CoV-2. Hamsters were given a primary mock or SARS-CoV-2 infection (culture media or 105 TCID50 USA/WA1/2020 isolate, respectively). Mock and SARS-CoV-2 infected hamsters were then given a secondary SARS-CoV-2 infection at 1, 2, 4, or 6 months post-primary infection (n = 14/time point/group). After the primary SARS-CoV-2 infection, hamsters developed anti-spike protein IgG, IgA, and neutralizing antibodies, and these antibodies were maintained for at least 6 months. Upon secondary SARS-CoV-2 challenge, previously SARS-CoV-2 infected animals were protected from weight loss, while all previously mock-infected animals became infected and lost weight. Importantly, despite having high titres of antibodies, one SARS-CoV-2 infected animal re-challenged at 4 months had a breakthrough infection with replicating virus in the upper and lower respiratory tract. These studies demonstrate immunity to SARS-CoV-2 is maintained for 6 months; however, protection may be incomplete and, even in the presence of high antibody titres, previously infected hosts may become re-infected.

Re-infection in COVID-19: Do we exaggerate our worries?

BACKGROUND

Protective long-term immunity following coronavirus disease 2019 (COVID-19) is unclear. The study evaluated the relationship between the vaccination status and risk factors in the re-infection of patients with a diagnosis of COVID-19 who reported to the Public Health Management System in a province in south-eastern Turkey.

METHODS

Patients with positive results for the severe acute respiratory syndrome coronavirus 2 by the real-time reverse transcription polymerase chain reaction (RT-PCR) test in respiratory samples were defined as confirmed cases. Reinfection was diagnosed in cases with COVID-19 real-time RT-PCR positivity, with or without COVID-19-like symptoms, in at least 90 days after the first infection/disease.

RESULTS

A total of 58 811 patients with the diagnosis of COVID-19 from March 11, 2020, to August 31, 2021, were included in the study. Re-infection was detected in 421 (0.7%) of all patients. The mean age of the cases was 38.0±16.0 years, and 51% of them were female. Eight (2.0%) of the cases resulted in death due to re-infection. No hospitalization or mortality was observed in fully vaccinated patients. Additionally, none of the mortal cases had completed the vaccination schedule.

CONCLUSIONS

We are concerned that the re-infection rates and mortality may increase due to new variant strains. Vaccination is the greatest weapon against progression to critical illness in re-infections, even with existing mutations. Therefore, it is important for those without a full vaccination schedule to be vaccinated, even if they have been previously infected.

Long-term, infection-acquired immunity against the SARS-CoV-2 Delta variant in a hamster model

The emergence of the SARS-CoV-2 Delta variant (B.1.617.2) raises concerns about potential reduced sensitivity of the virus to antibody neutralization and subsequent vaccine breakthrough infections. Here, we use a live virus neutralization assay with sera from Pfizer- and Moderna-vaccinated individuals to examine neutralizing antibody titers against SARS-CoV-2 and observe a 3.9- and 2.7-fold reduction, respectively, in neutralizing antibody titers against the Delta variant compared with an early isolate bearing only a D614G substitution in its spike protein. We observe similar reduced sensitivity with sera from hamsters that were previously infected with an early isolate of SARS-CoV-2. Despite this reduction in neutralizing antibody titers against the Delta variant, hamsters previously infected (up to 15 months earlier) with an early isolate are protected from infection with the Delta variant, suggesting that the immune response to the first infection is sufficient to provide protection against subsequent infection with the Delta variant.

A systematic review on SARS-CoV-2 remission: an Emerging challenge for its management, treatment, immunization strategies and post-treatment guidelines

The COVID-19 disease caused by severe acute respiratory syndrome coronavirus -2 (SARS-CoV-2) has posed as a major health concern for people all across the globe. Along with the increasing confirmed patients being readmitted with complaints for fever, cough, cold, the effective monitoring of 'relapse' of the SARS-CoV-2 virus in the previously discharged patients have become the next area of focus. However, availability of limited data on reactivation of SARS-CoV-2 makes the disease prognosis as well as the effective control of re-infection an immense challenge. Prompted by these challenges, we assessed the possibility of re-infection in discharged patients and the risk of the transmission, proficiency of RT-PCR results and approximate period required for the quarantine and the real challenges for the development of vaccine. In the present review, the published literature on all the possible cases of re-infection from February to July were reported, thereby selected 142 studies from a hub of overall 669 studies after full text screening. The incomplete virus clearance, poor sensitivity of the present diagnostic testing, emergence of mutant strains, insufficient mucus collection from the throat swab etc. are some of the possible causes of re-infection. The new protocols for management of COVID-19 discharged patients should be revised in the guidelines.

OMICRON (B.1.1.529): A new SARS-CoV-2 variant of concern mounting worldwide fear

Recent emergence of the SARS-CoV-2 variant as OMICRON has become a global concern. This short note highlights the identification and global spread of OMICRON which has spread over 77 nations by now, which resulted in many hypotheses about its origin and degree of infectivity. The detection of mutations in the RBD region of Spike protein is a concern by surpassing vaccine immunity. The ahead will speak about its transmission potentiality, infectivity, disease morbidity as well as its effect on COVID-19 vaccines.

Experimental re-infected cats do not transmit SARS-CoV-2

SARS-CoV-2 is the causative agent of COVID-19 and responsible for the current global pandemic. We and others have previously demonstrated that cats are susceptible to SARS-CoV-2 infection and can efficiently transmit the virus to naïve cats. Here, we address whether cats previously exposed to SARS-CoV-2 can be re-infected with SARS-CoV-2. In two independent studies, SARS-CoV-2-infected cats were re-challenged with SARS-CoV-2 at 21 days post primary challenge (DPC) and necropsies performed at 4, 7 and 14 days post-secondary challenge (DP2C). Sentinels were co-mingled with the re-challenged cats at 1 DP2C. Clinical signs were recorded, and nasal, oropharyngeal, and rectal swabs, blood, and serum were collected and tissues examined for histologic lesions. Viral RNA was transiently shed via the nasal, oropharyngeal and rectal cavities of the re-challenged cats. Viral RNA was detected in various tissues of re-challenged cats euthanized at 4 DP2C, mainly in the upper respiratory tract and lymphoid tissues, but less frequently and at lower levels in the lower respiratory tract when compared to primary SARS-CoV-2 challenged cats at 4 DPC. Viral RNA and antigen detected in the respiratory tract of the primary SARS-CoV-2 infected cats at early DPCs were absent in the re-challenged cats. Naïve sentinels co-housed with the re-challenged cats did not shed virus or seroconvert. Together, our results indicate that cats previously infected with SARS-CoV-2 can be experimentally re-infected with SARS-CoV-2; however, the levels of virus shed was insufficient for transmission to co-housed naïve sentinels. We conclude that SARS-CoV-2 infection in cats induces immune responses that provide partial, non-sterilizing immune protection against re-infection.

Persistence of symptoms after improvement of acute COVID19 infection, a longitudinal study

With the number of coronavirus disease 2019 (COVID-19) infected patients increasing all over the world, a large number of survivors have reported changes in their quality of life or experienced re-infection. So, we aimed to detect the percentage, type, and risk factors of persistent symptoms after improvement from acute COVID-19 infection and to detect the percentage of COVID-19 re-infection and degree of severity of the second infection. One hundred seventy-two (59 male, 113 female) patients who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were followed up via mobile phone every 2 months for 8 to 10 months. After recovery, 105 patients (61%) (30 male, 75 female) reported one or more COVID-19 persistent symptoms. Fatigue, dyspnea, and depression were the most common persistent symptoms representing 37.3%, 22%, 22%, respectively. We found that age was independently related to the persistence of symptoms. During the follow-up, six females (3.5%) had laboratory-confirmed COVID-19 re-infection. Their mean age was 35.7 ± 11 years. The mean interval from the complete recovery of the first infection to the onset of the second one was 53 ± 22.2 days and ranged from 30 to 90 days. The second infection was milder in severity than the first infection in 83.33% of cases. There was a high percentage of patients who complained of persistent symptoms after recovery from COVID-19. Fatigue and headache were the most common persistent symptoms. Age was considered a risk factor for persistent symptoms. Re-infection with SARS-CoV-2 can occur after recovery.

Complexities in Case Definition of SARS-CoV-2 Reinfection: Clinical Evidence and Implications in COVID-19 Surveillance and Diagnosis

Reinfection cases have been reported in some countries with clinical symptoms ranging from mild to severe. In addition to clinical diagnosis, virus genome sequence from the first and second infection has to be confirmed to either belong to separate clades or had significant mutations for the confirmation of SARS-CoV-2 reinfection. While phylogenetic analysis with paired specimens offers the strongest evidence for reinfection, there remains concerns on the definition of SARS-CoV-2 reinfection, for reasons including accessibility to paired-samples and technical challenges in phylogenetic analysis. In light of the emergence of new SARS-CoV-2 variants that are associated with increased transmissibility and immune-escape further understanding of COVID-19 protective immunity, real-time surveillance directed at identifying COVID-19 transmission patterns, transmissibility of emerging variants and clinical implications of reinfection would be important in addressing the challenges in definition of COVID-19 reinfection and understanding the true disease burden.

How strong is the evidence that it is possible to get SARS-CoV-2 twice? A systematic review

With a large number of coronavirus disease 2019 (Covid-19) patients being discharged from hospital with negative test results for SARS-CoV-2, it has been reported that several recovered cases tested positive after discharge (re-positive, RP). This finding has raised several important questions for this novel coronavirus and Covid-19 disease. In this review, we have discussed several important questions, including: (1) Can the virus re-infect recovered individuals? (2) What are the possible causes of the re-positive reverse transcriptase-polymerase chain reaction (RT-PCR) test in recovered patients? (3) What are the implications of these re-positive cases concerning the spread of the virus? Understanding how recovery from Covid-19 confers immunity to decrease the risk of re-infection is needed to inform current efforts to safely scale back population-based interventions, such as physical distancing. We have also described what is currently known about the immune response to Covid-19, highlighted key gaps in knowledge, and identified opportunities for future research. Overall, the quality of the evidence is poor and we describe the features that should be described for future cases.

Clinical evaluation of conventional human coronavirus infection in adults

Human coronaviruses (HCoVs) are globally distributed and cause a range of respiratory symptoms. Reports of the clinical features of HCoV infection are limited, especially in adults because of mild upper respiratory tract disease and no specific therapy available. Here we aim to evaluate the features of HCoV infection in clinical settings. Adult patients with respiratory symptoms from October 2014 to September 2019 at Nagasaki Genbaku Isahaya Hospital were enrolled. The multiplex reverse-transcription polymerase chain reaction (RT-PCR) was performed for 15 viruses including HCoVs and 8 bacterial species on their respiratory specimens. A total of 121 cases were recruited with HKU1, OC43, 229E and NL63 strains in 80, 21, 12 and 11 cases, respectively. The percent of HCoV-infected patients peaked (47.5%) in winter. Symptoms of fever (69.4%) and cough (47.9%), and comorbidities of asthma/cough variant asthma (34.7%) were frequently observed. Lymphocytopenia and increased C-reactive protein were observed on the laboratory test. Co-infection with other viruses was identified in 38.8% of cases. In the repeat-positive cases, 42% cases were repeat positive within 100 days. HCoV-infected patients showed winter seasonality with a high frequency of comorbidity with asthma, and co-infection. Re-infection within an early period was suspected but required further consideration.

SARS-CoV-2 re-infection versus prolonged shedding: A case series

Since the start of the SARS‐CoV‐2 pandemic, it has been difficult to differentiate between SARS‐CoV‐2 re‐infection and prolonged RNA shedding. In this report, we identified patients with positive RT‐PCR results for SARS‐CoV‐2 ≥70 days apart. Clinical and laboratory data were collected and criteria were applied to discern whether the presentation was consistent with SARS‐CoV‐2 re‐infection or prolonged viral RNA shedding. Eleven individuals met the initial testing criteria, of which, seven met at least one criteria for re‐infection and four were consistent with prolonged RNA shedding. These data demonstrate the need for criteria to differentiate SARS‐CoV‐2 re‐infection from prolonged RNA shedding.

Public health interventions for preventing re-infection of Opisthorchis viverrini: application of the self-efficacy theory and group process in high-prevalent areas of Thailand

OBJECTIVE

To study the effectiveness of public health interventions in preventing Opisthorchis viverrini (OV) re-infection in high-prevalence areas of Thailand.

METHODS

68 people from Sisaket, the province with the second-highest prevalence in Thailand, who tested positive for OV eggs in faeces and took praziquantel before the start of the study, participated. 34 participants were allocated to the experimental group, which received a 12-week public health intervention based on the self-efficacy theory and group process between July and October 2018. The control group received the usual services. Data were collected using a questionnaire with a reliability of 0.84. Faecal examinations using the formalin-ether concentration technique were conducted before and after the experiment. The re-infection rate was analysed after the experimental 12 weeks and after one year. Descriptive and inferential statistics, including paired t-test and independent t-test, were employed for data analysis.

RESULTS

After the experiment, the mean scores of knowledge, perceived self-efficacy, self-efficacy expectation and OV prevention behaviour of the experimental group were significantly higher than before the experiment and also higher than scores of the control group (P < 0.05).

CONCLUSION

The public health intervention is useful. It educated the experimental group about OV, perceived self-efficacy and self-efficacy expectation in changing behaviour to prevent OV re-infection. As a result, no re-infections were observed after the 12-week intervention nor at the one-year follow-up. Public health benefits will be evident if the results are extended to other high-prevalence areas.

Case series of four re-infections with a SARS-CoV-2 B.1.351 variant, Luxembourg, February 2021

We describe four SARS-CoV-2 re-infections with a B.1.351 variant in 2021, in healthcare workers (HCWs) previously infected in 2020, before detection of this variant in Europe. Cases live in France, near the border with Luxembourg, where variants B.1.351 and B.1.1.7 circulated. All work in the same hospital unit where a cluster of COVID 19 with B1.351 variant occurred, affecting patients and HCWs. Before the cluster onset, HCWs used surgical masks, as per recommendations. After cluster onset, HCWs used FFP2 masks.

Protection against reinfection with D614- or G614-SARS-CoV-2 isolates in golden Syrian hamster

Reinfections with SARS-CoV-2 have already been documented in humans, although its real incidence is currently unknown. Besides having a great impact on public health, this phenomenon raises the question of immunity generated by a single infection is sufficient to provide sterilizing/protective immunity to a subsequent SARS-CoV-2 re-exposure. The Golden Syrian hamster is a manageable animal model to explore immunological mechanisms able to counteract COVID-19, as it recapitulates pathological aspects of mild to moderately affected patients. Here, we report that SARS-CoV-2-inoculated hamsters resolve infection in the upper and lower respiratory tracts within seven days upon inoculation with the Cat01 (G614) SARS-CoV-2 isolate. Three weeks after the primary challenge, and despite high titres of neutralizing antibodies, half of the animals were susceptible to reinfection by both identical (Cat01, G614) and variant (WA/1, D614) SARS-CoV-2 isolates. However, upon re-inoculation, only nasal tissues were transiently infected with much lower viral replication than those observed after the first inoculation. These data indicate that a primary SARS-CoV-2 infection is not sufficient to elicit a sterilizing immunity in hamster models but protects against lung disease.

A Case of COVID-19 Re-Infection in a Liver Transplant Patient

Coronavirus disease 2019 (COVID-19) is an ongoing worldwide pandemic infection. The exact incidence of disease re-infection or recurrence remains unknown. One particular at-risk population includes individuals with solid organ transplantation on immunosuppression. We present a case of COVID-19 re-infection in a chronically immunocompromised liver transplant patient. A 53-year-old female presented to the Emergency Department (ED) with nausea, vomiting, diarrhea, and myalgias. She was found to test positive for COVID-19. Her relevant medical history included liver transplantation on chronic immunosuppression. More recently, she had tested positive for COVID-19 approximately three months prior to this and was hospitalized at that time for encephalopathy and treated with remdesivir and convalescent plasma. She had subsequently recovered with negative COVID-19 testing in the interim. On the ED presentation with presumed re-infection, her disease was deemed to be mild with lack of severe symptoms or pulmonary involvement, and she was discharged with outpatient follow-up for monoclonal antibody infusion therapy. We describe a scenario of presumed COVID-19 re-infection in a liver transplant patient. To our knowledge, this is a rare event and has been reported internationally in only a handful of individuals. We surmise that immunosuppression could offer some protection from the inflammatory cascade of the initial disease process in COVID-19 given the relatively mild disease observed in our patient. On the other hand, a less robust immune response may decrease humoral immunity and leave patients at greater risk of re-infection. Further investigation is necessary to delineate COVID-19 disease re-infection versus relapse, especially in the setting of an immunocompromised state.

Early modified primary closure for treatment of cardiac implantable electronic device pocket infections

BACKGROUND

Guidance for wound management of the vacated generator pocket in cardiac implantable electronic device (CIED) pocket infections after removal of all hardware and tissue debridement is limited. The typical surgical technique for management of a purulent wound is to allow healing by secondary intention. An alternative approach uses negative pressure wound therapy with or without delayed primary closure. While effective in managing infection, these approaches increase hospital length of stay and costs. We present our experience with a third option: modified early primary wound closure over a suction device.

METHODS

All patients with CIED pocket infections who presented to our institution between September 2018 and October 2020 underwent extraction of hardware and modified primary wound closure over a negative pressure Jackson-Pratt drain. Length of hospital and postoperative stay, complications, and recurrent infections were recorded.

RESULTS

During the study period, 14 patients underwent modified primary wound closure for CIED pocket infections. Mean length of hospital stay was 6.64 days ± 4.01 days (standard deviation [SD]). Mean postoperative length of stay was 3.92 ± 2.21 days (SD). Two patients (both on intravenous heparin for mechanical valve prostheses) required re-exploration for bleeding. No patients developed recurrent infection at a mean follow up of 363 ± 245 days (SD).

CONCLUSION

Based on our experience, early modified primary wound closure for CIED pocket infections appears to be safe and allows for prompt discharge with no observed re-infections.

COVID-19 re-infection in Shahroud, Iran: a follow-up study

Although many people became infected and recovered during the COVID-19 epidemic, the immunity duration and re-infection in recovered patients have recently attracted many researchers. The aim of this study was to evaluate the recurrence of the infection in recovered individuals over a 9-month period after the onset of the COVID-19 epidemic. In this study, data related to COVID-19 patients in Shahroud city were collected using the electronic system for registering suspicious patients and also by checking patients' hospital records. In this study, from 20 March 2020 to 20 November 2020 (9 months), a total of 8734 suspected patients with respiratory symptoms were observed and followed up. RT-PCR was positive for 4039 patients. During this period, out of the total number of positive cases of COVID-19, 10 cases became re-infected after complete recovery. The risk of re-infection was 2.5 per thousand (0.95 CI 1.2–4.5). The mean time interval between the first infection and re-infection was 134.4 ± 64.5 days (range 41–234 days). The risk of re-infection between male and females was not statistically different (1.98 per 1000 women and 2.96 per 1000 men). Exposure to COVID-19 may not establish long-term protective immunity to all patients and may predispose them to re-infection. This fact can be reminded that the use of masks, social distancing and other preventive measures are very important in recovered patients and should be emphasised especially in health care personnel who are more exposed to the virus.

SARS-CoV-2 re-infection risk in Austria

BACKGROUND

A key question concerning coronavirus disease 2019 (COVID-19) is how effective and long lasting immunity against this disease is in individuals who were previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We aimed to evaluate the risk of SARS-CoV-2 re-infections in the general population in Austria.

METHODS

This is a retrospective observational study using national SARS-CoV-2 infection data from the Austrian epidemiological reporting system. As the primary outcome, we aim to compare the odds of SARS-CoV-2 re-infections of COVID-19 survivors of the first wave (February to April 30, 2020) versus the odds of first infections in the remainder general population by tracking polymerase chain reaction (PCR)-confirmed infections of both groups during the second wave from September 1 to November 30, 2020. Re-infection counts are tentative, since it cannot be excluded that the positive PCR in the first and/or second wave might have been a false positive.

RESULTS

We recorded 40 tentative re-infections in 14 840 COVID-19 survivors of the first wave (0.27%) and 253 581 infections in 8 885 640 individuals of the remaining general population (2.85%) translating into an odds ratio (95% confidence interval) of 0.09 (0.07 to 0.13).

CONCLUSIONS

We observed a relatively low re-infection rate of SARS-CoV-2 in Austria. Protection against SARS-CoV-2 after natural infection is comparable with the highest available estimates on vaccine efficacies. Further well-designed research on this issue is urgently needed for improving evidence-based decisions on public health measures and vaccination strategies.

SARS-CoV-2 re-infection: development of an epidemiological definition from India

The current investigation was conducted with the objective to develop an epidemiological case definition of possible severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) re-infection and assess its magnitude in India. The epidemiological case definition for SARS-CoV-2 re-infection was developed from literature review of data on viral kinetics. For achieving second objective, the individuals who satisfied the developed case definition for SARS-CoV-2 re-infection were contacted telephonically. Taking available evidence into consideration, re-infection with SARS-CoV-2 in our study was defined as any individual who tested positive for SARS-CoV-2 on two separate occasions by either molecular tests or rapid antigen test at an interval of at least 102 days with one negative molecular test in between. In this archive based, telephonic survey, 58 out of 1300 individuals (4.5%) fulfilled the above-mentioned definition; 38 individuals could be contacted with healthcare workers (HCWs) accounting for 31.6% of the cases. A large proportion of participants was asymptomatic and had higher Ct value during the first episode. While SARS-CoV-2 re-infection is still a rare phenomenon, there is a need for epidemiological definition of re-infection for establishing surveillance systems and this study contributes to such a goal.Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) re-infection is an emerging concern and there is a need to define it. Therefore, working epidemiological case definition for re-infection was developed and its magnitude was explored via archive-based, telephonic survey. Re-infection with SARS-CoV-2 was defined as two positive tests at an interval of at least 102 days with one interim negative test. Thirty-eight of the 58 eligible patients could be contacted with 12 (31.6%) being HCWs. Majority of the participants were asymptomatic and had higher Ct value during their first episode. To conclude, a working epidemiological case definition of SARS-CoV-2 re-infection is important to strengthen surveillance. The present investigation contributes to this goal and records reinfection in 4.5% of SARS-CoV-2 infected individuals in India.

Relapse or Re-Infection, the Situation of Recurrent Tuberculosis in Eastern China

Purpose

Recurrent tuberculosis (TB) is defined by more than one TB episode per patient and is caused by re-infection with a new Mycobacterium tuberculosis (Mtb) strain or relapse with the previous strain. Recurrence of TB is one important obstacle for End TB strategy in the world and elucidating the triggers of recurrence is important for the current TB control strategy in China. This study aimed to analyze the sources of recurrent TB by the molecular genotyping method.

Method

A population-based surveillance was undertaking on all culture-positive TB cases in Jiangsu province, China from 2013 to 2019. Phenotypic drug susceptibility test (DST) by proportion method and mycobacterial interspersed repetitive units-variable number of tandem repeat (MIRU-VNTR) were adopted for drug resistance and genotype detection.

Results

A total of 1451 culture-positive TB patients were collected and 30 (2.06%, 30/1451) TB cases had recurrent TB episodes. Except 7 isolates were failed during subculture, 23 paired isolates were assessed. After genotyping by MIRU-VNTR, 12 (52.17%, 12/23) paired recurrence TB were demonstrated as relapse and 11 (47.83%,11/23) paired cases were identified as re-infection. The average interval time for recurrence was 24.04 (95%CI: 19.37-28.71) months, and there was no significant difference between relapse and re-infection. For the relapsed cases, two paired isolates exhibited drug resistance shifting, while four paired isolates revealed inconsistent drug resistance among the re-infection group including two multidrug-resistant tuberculosis (MDR-TB) at the second episode.

Conclusion

Relapse and re-infection contributed equally to the current situation of recurrence TB in Jiangsu, China. Besides, more efficient treatment assessment, specific and vigorous interventions are urgently needed for MDR-TB patients, considering obvious performance among re-infection cases.

Clinical and Laboratory Findings in Patients with Potential SARS-CoV-2 Reinfection, May-July 2020

BACKGROUND

We investigated patients with potential SARS-CoV-2 reinfection in the United States during May-July 2020.

METHODS

We conducted case finding for patients with potential SARS-CoV-2 reinfection through the Emerging Infections Network. Cases reported were screened for laboratory and clinical findings of potential reinfection followed by requests for medical records and laboratory specimens. Available medical records were abstracted to characterize patient demographics, comorbidities, clinical course, and laboratory test results. Submitted specimens underwent further testing, including RT-PCR, viral culture, whole genome sequencing, subgenomic RNA PCR, and testing for anti-SARS-CoV-2 total antibody.

RESULTS

Among 73 potential reinfection patients with available records, 30 patients had recurrent COVID-19 symptoms explained by alternative diagnoses with concurrent SARS-CoV-2 positive RT-PCR, 24 patients remained asymptomatic after recovery but had recurrent or persistent RT-PCR, and 19 patients had recurrent COVID-19 symptoms with concurrent SARS-CoV-2 positive RT-PCR but no alternative diagnoses. These 19 patients had symptom recurrence a median of 57 days after initial symptom onset (interquartile range: 47 - 76). Six of these patients had paired specimens available for further testing, but none had laboratory findings confirming reinfections. Testing of an additional three patients with recurrent symptoms and alternative diagnoses also did not confirm reinfection.

CONCLUSIONS

We did not confirm SARS-CoV-2 reinfection within 90 days of the initial infection based on the clinical and laboratory characteristics of cases in this investigation. Our findings support current CDC guidance around quarantine and testing for patients who have recovered from COVID-19.

Persistence of SARS-CoV-2: a new paradigm of COVID-19 management

Abstract

Full attention must be given to the follow-up of patients recovered from Coronavirus disease 2019, which developed in Wuhan, China in December 2019. Among the most serious issues since the emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 has been whether those who had it can experience a second episode of infection and what that implies for immunity. The earlier studies on COVID-19 disease focused primarily on the epidemiological, clinical, and radiological characteristics of patients with CO-VID-19. However, conclusions of these studies still require to be warranted by more careful design, larger sample size and statistically well structured studies. COVID-19 is an under-studied infection, and several aspects of viral transmission and clinical progress remain at present unclear. There is a concern about the persistence of SARS-CoV-2 on various surfaces and in the respiratory system of patients who have survi-ved. One of the most concerning issues since the emergence of the SARS-CoV-2 is persistence in patients and whether patients can be re-infected. After hospital discharge, recovered patients were reported to have positive SARS-CoV-2 test in China, Japan, and South Korea. In addition to the persistence of the virus, SARS-CoV-2 re-infection may occur in survivors. In this paper, we focused on the evidence of persistence and re-infection of SARS-CoV-2.

COVID-19 re-infection or persistent infection in patient with acute myeloid leukaemia M3: a mini review

Coronavirus disease 2019 (COVID-19) pandemic has affected more than 40 million people worldwide. Some patients had episodes of symptom recurrence after the first episode of infection with variable intervals. There are multiple issues and hypotheses about re-infection or re-activation of the virus, especially in immunocompromised patients. In this paper, we present details of an individual with a recent history of COVID-19 who proceeded to acute myeloid leukaemia M3 and immunosuppression by chemotherapy, then we review some recently published articles about possible re-infection or re-activation.

No Evidence of Re-infection or Person-to-Person Transmission in Cured COVID-19 Patients in Guangzhou, a Retrospective Observational Study

Objectives: To clarify the clinical characteristics of cured patients with coronavirus disease (COVID-19), and to clarify the re-infection and person-to-person transmission in the cured.

Methods: A total of 187 cured COVID-19 patients with antibody test were followed up every 2 weeks in this retrospective observational study. Assessment for general condition, symptoms, epidemiological contact history, polymerase chain reaction (PCR) assay, and antibody tests were performed and recorded. Information from Guangzhou CDC was also screened.

Results: There were 33 (17.6%) patients with negative results for IgG and 35 (18.7%) patients with positive results for IgM. The average days of antibody detection from disease onset were 53.0. PCR assay was positive in 10 (5.3%) patients during the follow-up. Neither IgG nor IgM results showed a relationship with PCR test results (all P > 0.05). Neither re-infection nor person-to-person transmission was found in the cured patients. Factors associated with appearance of antibody comprised hospitalization days (OR: 1.06, 95%CI: 1.02–1.11, P = 0.006) and antibiotics treatment (OR: 3.50, 95%CI: 1.40–8.77, P = 0.007).

Conclusions: In our study, no evidence of person-to-person transmission was found in cured COVID-19 patients. There seemed to be no re-infection in the cured COVID-19 patients in Guangzhou. These finding suggest that the cured do not cause the spread of disease. Additionally, neither IgG nor IgM can be used to replace the PCR test in cured patients.

COVID-19 reinfection: Linked Possibilities and future outlook

SARS-CoV-2 is the third major coronavirus epidemic to affect humans. There had been multiple instances of patients turning positive after recovering from SARS-2-CoV infection. Though many different theories emerge, false positive RT-PCR is logically the foremost cause and there is a general consensus that during quarantine re-infection from outside seems unlikely when strictly adhered to. As many new strains emerge worldwide during the course of on-going pandemic, the chances of re-infection cannot be ignored as it may contribute to false negative RT-PCR test results. SARS-2-CoV though a novel virus, is phylogenetically similar to SARS-like CoV with around 79% similarity. Studies on immunological response to these infections suggest that antibodies formed after infection confers immunity only for a short period of time before it starts to wane. Also studies on SARS-CoV-2 suggest that antibody formation and longevity of immunity in an individual is dependent on the strain of coronavirus, its severity and age of the person infected. All these considerations demand reviewing the treatment duration, discharge criteria, appropriate use of imaging techniques and importance of risk communication and health education to those recovered.

Chlamydia trachomatis L2c Infection in a Porcine Model Produced Urogenital Pathology and Failed to Induce Protective Immune Responses Against Re-Infection

The current study was designed to evaluate the pathogenesis, pathology and immune response of female genital tract infection with Chlamydia trachomatis L2c, the most recently discovered lymphogranuloma venereum strain, using a porcine model of sexually transmitted infections. Pigs were mock infected, infected once or infected and re-infected intravaginally, and samples were obtained for chlamydial culture, gross and microscopic pathology, and humoral and cell-mediated immunity. Intravaginal inoculation of pigs with this bacterium resulted in an infection that was confined to the urogenital tract, where inflammation and pathology were caused that resembled what is seen in human infection. Re-infection resulted in more severe gross pathology than primary infection, and chlamydial colonization of the urogenital tract was similar for primary infected and re-infected pigs. This indicates that primary infection failed to induce protective immune responses against re-infection. Indeed, the proliferative responses of mononuclear cells from blood and lymphoid tissues to C. trachomatis strain L2c were never statistically different among groups, suggesting that C. trachomatis-specific lymphocytes were not generated following infection or re-infection. Nevertheless, anti-chlamydial antibodies were elicited in sera and vaginal secretions after primary infection and re-infection, clearly resulting in a secondary systemic and mucosal antibody response. While primary infection did not protect against reinfection, the porcine model is relevant for evaluating immune and pathogenic responses for emerging and known C. trachomatis strains to advance drug and/or vaccine development in humans.

Reduction of Reinfection Rates with Opisthorchis viverrini through a Three-Year Management Program in Endemic Areas of Northeastern Thailand

To clarify the reinfection profile associated with risk factors of opisthorchiasis, we conducted an epidemiological study on the chemotherapeutic effects on reinfection with O. viverrini in the endemic areas of Northeastern Thailand for 3 years. A total of 3,674 fecal samples were collected from participants in villages of 5 provinces. They were examined microscopically using a modified technique of formalin ethyl-acetate concentration. Egg-positive residents were reexamined year (2018) by year (2019) after treatment with a single dose (40 mg/kg) of praziquantel. Health education was provided to the participants yearly. The egg-positive rate of O. viverrini was 14.3%, and was highest (22.2%) in the 20–30 year-old group in 2017. The egg positive rate was 15.3% in dogs and 11.4% cats. Human reinfection rate was 15.5% and 6.3% in next 2 years, and was highest (23.2%) among the fishermen. Relative risk factors of reinfection were significantly higher for males, over 40-year-old age, or working as fishermen or farmers, and eating uncooked fish within the preceding year. A significant difference resulting from a health education program was observed in the third year. Therefore, health education and sustainable surveillance for opisthorchiasis should be maintained to decrease the risk of reinfection.

The benefit of culture-independent methods to detect bacteria and fungi in re-infected root filled teeth: a pilot study

AIM

To identify dominant microorganisms in root filled teeth with apical periodontitis by Pan-PCRs in comparison with a culture-dependent approach, focusing on fungal species profiling.

METHODOLOGY

The root filling material (gutta-percha) removed from 42 teeth with periapical radiolucencies undergoing root canal retreatments was analysed by molecular genetics techniques. Real-Time Pan-PCRs were conducted for the diagnosis of predominant bacteria (targeting 16S rDNA) and fungi (targeting ITS1-2 region). Identification of microorganisms was performed by Sanger sequencing of the PCR products and BLAST analysis. Additionally, subgingival plaque samples were collected and cultured to review the composition of the microbial flora. The McNemar test and the repeated measures anova were used for statistical analyses (significance level was set at P < 0.05).

RESULTS

Overall, 42/42 plaque samples had bacterial growth, whereas 32/42 gutta-percha samples had bacterial growth with a dominance of Streptococcus spp. (12/42) and Enterococcus faecalis (9/42). The mean number of bacterial taxa per gutta-percha sample was 1.6 cultivatable taxa, significantly lower than in the plaque sample that had six taxa/sample (P < 0.001). Fungus-specific cultures were negative for gutta-percha samples, and only one plaque sample had growth of a fungus. In total, 36/42 plaque samples were positive in bacterial Pan-PCRs. In bacterial Pan-PCRs of 31/42 gutta-percha samples, dominant microorganisms were identified including Streptococcus spp. (5/42) and E. faecalis (4/42). Moreover, in 7/42 gutta-percha samples, DNA of bacteria which are difficult-to-cultivate in microbiology routine culture (Acinetobacter,Pyramidobacter,Bacteroidetes,Synergistes,Atopobium and Pseudoramibacter) was found. DNA of Candida spp. was detected in 5/42 root canals by fungal Pan-PCR (1/5) and genus-specific Candida-PCR (5/5).

CONCLUSIONS

Pan-PCR assays remain appropriate as a broad-range approach for the detection of a dominant pathogen in gutta-percha samples which have less diverse microbial composition. The molecular genetic Pan-PCR approach has the advantage of detecting microorganisms that are as-yet-uncultivable or difficult-to-cultivate and should be therefore complement conventional microbiological diagnostics.

Coronavirus disease 2019 re-infection: first report from Turkey

There are concerns about the possibility of SARS-CoV-2 reinfection and recently, a patient with SARS-CoV-2 re-infection (or COVID-19) confirmed by epidemiological, clinical, serological and genomic analyses have been published. We have noticed another patient with SARS-CoV-2 re-infection based on clinical and laboratory studies: A 23-year-old woman presented to her hospital with fever (39°C), chills, fatigue, cough, headache, sore throat, muscle and joint pain on April 9, 2020. On examination, oropharynx was mildly hyperemic, and chest auscultation was normal. SARS-CoV-2 PCR from nasopharyngeal specimen was ordered. She was given isotonic saline and acetaminophen and prescribed azithromycin and acetaminophen and sent home for isolation. SARS-CoV-2 PCR was reported positive and she was given hydroxychloroquine for five days. She improved in 10 days and PCR studies on April 22, and April 27 remained negative. On 4 August 2020, she was re-admitted with fever (38.7°C), chills, fatigue, loss of appetite, taste and smell loss, muscle and joint pain. On examination, oropharynx and chest auscultation were normal. SARS-CoV-2 PCR was reported positive and she was prescribed hydroxychloroquine, acetaminophen and sent home for isolation again. She improved in one week (taste-smell loss improved in 10 days) and on follow-up visit after 14 days, she was doing well. PCR was negative on 17 August 2020. Her anti-SARS-CoV-2 antibodies were negative on 17 August 2020 and slightly positive (2.14 signal-to-cutoff) on 29 August 2020. Previous report from To et al. [Clin Infect Dis. 2020;ciaa1275. doi:10.1093/cid/ciaa1275] showed that viral genomes from first and second episodes belonged to different clades/lineages. They described second episode of asymptomatic infection occurred 142 day after the first symptomatic one. Our patient is the first report, describing two symptomatic episodes 116 days apart. We conclude that as the patients recovered from COVID-19 increases, increased awareness may delineate the characteristics of re-infection.

COVID-19 re-infection by a phylogenetically distinct SARS-coronavirus-2 strain confirmed by whole genome sequencing

Background

Waning immunity occurs in patients who have recovered from COVID-19. However, it remains unclear whether true re-infection occurs.

Methods

Whole genome sequencing was performed directly on respiratory specimens collected during two episodes of COVID-19 in a patient. Comparative genome analysis was conducted to differentiate re-infection from persistent viral shedding. Laboratory results, including RT-PCR Ct values and serum SARS-CoV-2 IgG, were analyzed.

Results

The second episode of asymptomatic infection occurred 142 days after the first symptomatic episode in an apparently immunocompetent patient. During the second episode, there was serological evidence of elevated C-reactive protein and SARS-CoV-2 IgG seroconversion. Viral genomes from first and second episodes belong to different clades/lineages. Compared to viral genomes in GISAID, the first virus genome has a stop codon at position 64 of orf8 leading to a truncation of 58 amino acids, and was phylogenetically closely related to strains collected in March/April 2020, while the second virus genome was closely related to strains collected in July/August 2020. Another 23 nucleotide and 13 amino acid differences located in 9 different proteins, including positions of B and T cell epitopes, were found between viruses from the first and second episodes.

Conclusions

Epidemiological, clinical, serological and genomic analyses confirmed that the patient had re-infection instead of persistent viral shedding from first infection. Our results suggest SARS-CoV-2 may continue to circulate among the human populations despite herd immunity due to natural infection or vaccination. Further studies of patients with re-infection will shed light on protective correlates important for vaccine design.

Impact of community piped water coverage on re-infection with urogenital schistosomiasis in rural South Africa

Previously, we demonstrated that coverage of piped water in the seven years preceding a parasitological survey was strongly predictive of Schistosomiasis haematobium infection in a nested cohort of 1976 primary school children (Tanser, 2018). Here, we report on the prospective follow up of infected members of this nested cohort (N = 333) for two successive rounds following treatment. Using a negative binomial regression fitted to egg count data, we found that every percentage point increase in piped water coverage was associated with 4.4% decline in intensity of re-infection (incidence rate ratio = 0.96, 95% CI: 0.93–0.98, p=0.004) among the treated children. We therefore provide further compelling evidence in support of the scaleup of piped water as an effective control strategy against Schistosoma haematobium transmission.

Severe Clinical Outcomes of Tuberculosis in Kharkiv Region, Ukraine, Are Associated with Beijing Strains of Mycobacterium tuberculosis

Genotypic variation in Beijing lineages of Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB), has been associated with hyper virulence and the spread of extensively and multiple drug (X/MDR) resistant MTB strains in Eastern Europe, Central Asia, and East Asia. The clinical outcomes of 215 new cases of TB among the population of the Kharkiv region of Eastern Ukraine were analyzed to uncover factors associated with severe infection. Infecting MTB strains were profiled by 5 locus exact tandem repeats (ETRs) and 15 locus mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) genotyping. Among diverse MTB genotypes discovered in Ukraine, the Beijing genotype (MIRU-VNTR 42425) was significantly associated with risk factors for severe outcomes of disease in the study population, including TB/HIV co-infection and treatment failure. Strain replacement (superinfection) was observed in 10 patients, suggesting repeated exposure to novel MTB strains in hospital or community settings. Inclusion of MTB genotyping data may identify at-risk patients and improve treatment adherence to prevent X/MDR development for effective public health response against tuberculosis in Ukraine.

High response and re-infection rates among people who inject drugs treated for hepatitis C in a community needle and syringe programme

To achieve WHO hepatitis C virus (HCV) elimination targets by 2030, mathematical models suggest there needs to be significant scale-up of treatment among people who inject drugs (PWID). We tested whether people who actively inject drugs can be recruited and treated successfully through a community needle and syringe programme (NSP), and assessed rates of re-infection. 105 HCV RNA positive participants were enrolled prospectively. Participants were recruited from the largest NSP in Dundee over 42 months. 94/105 individuals commenced treatment. Genotype 1 (G1) individuals (n = 37) were treated with peg-interferon+ribavirin+Simepravir/Telaprevir. Genotype 2/3 (G2/3) (n = 57) received peg-interferon+ribavirin. Weekly study visits took place within the NSP. Mean age of participants was 34.0 years (SD 6.9), 71.3% (61/94) were male. One in five (20/94) participants were homeless. 68.1% (64/94) were on OST (opiate substitution therapy) at enrolment; participants injected median 6.5 times/wk. In terms of clinical outcomes, >80% treatment adherence was 71.3% (67/94). There was no difference in SVR-12 rates by genotype: 81.0% (30/37) for G1 and 82.5% (47/55) for G2/3. At 18 months post-treatment, 15/77 participants were reinfected, followed up over 69.8 person-years, yielding a re-infection rate of 21.5/100 person-years (95% CI 13.00-35.65). This trial demonstrates that HCV treatment can be delivered successfully to the target population of treatment as prevention strategies. We report higher rates of re-infection than existing estimates among PWID. Scale-up of HCV treatment should be pursued alongside a comprehensive programme of harm reduction interventions to help minimize re-infection and reduce HCV transmission.

Contribution of Fcγ Receptor-Mediated Immunity to the Pathogenesis Caused by the Human Respiratory Syncytial Virus

The human Respiratory Syncytial Virus (hRSV) is the leading cause of severe acute lower respiratory tract infections (ALRTIs) in humans at all ages and is the main cause of hospitalization due to pneumonia, asthma, and bronchiolitis in infants. hRSV symptoms mainly develop due to an excessive host immune and inflammatory response in the respiratory tissue. hRSV infection during life is frequent and likely because of non-optimal immunological memory is developed against this virus. Vaccine development against this pathogen has been delayed after the detrimental effects produced in children by vaccination with a formalin-inactivated hRSV preparation (FI-hRSV), which caused enhanced disease upon natural viral infection. Since then, several studies have focused on understanding the mechanisms underlying such disease exacerbation. Along these lines, several studies have suggested that antibodies elicited by immunization with FI-hRSV show low neutralizing capacity and promote the formation of immune complexes containing hRSV (hRSV-ICs), which contribute to hRSV pathogenesis through the engagement of Fc gamma receptors (FcγRs) expressed on the surface of immune cells. Furthermore, a role for FcγRs is supported by studies evaluating the contribution of these molecules to hRSV-induced disease. These studies have shown that FcγRs can modulate viral clearance by the host and the inflammatory response triggered by hRSV infection. In addition, ICs can facilitate viral entry into host cells expressing FcγRs, thus extending hRSV infectivity. In this article, we discuss current knowledge relative to the contribution of hRSV-ICs and FcγRs to the pathogenesis caused by hRSV and their putative role in the exacerbation of the disease caused by this virus after FI-hRSV vaccination. A better understanding FcγRs involvement in the immune response against hRSV will contribute to the development of new prophylactic or therapeutic tools to promote virus clearance with limited inflammatory damage to the airways.

Genomic Analysis of Consecutive Acinetobacter baumannii Strains From a Single Patient

Acinetobacter baumannii is one of the most important nosocomial pathogens, and thus it is required to investigate how it disseminate in hospitals and infect patients. We performed whole genome sequencing for 24 A. baumannii strains isolated successively from the blood of a single patient to evaluate whether repeated infections were due to re-infection or relapse infection and to investigate within-host evolution. The whole genome of the first strain, BL1, was sequenced de novo using the PacBio RSII system. BL2-BL24, were sequenced with an Illumina Hiseq4000 and mapped to the genome sequences of BL1. We identified 42 single-nucleotide variations among the strains. The SNVs differentiated the strains into three groups, BL1, BL2-BL16, and BL17-BL24, indicating that the patient suffered from re-infections or co-infections by similar, but different strains. The results also showed that A. baumannii strains in each group were rather stable at the genomic level. Our study emphasizes the importance of intensive infection control.

Immunity Against Leishmania major Infection: Parasite-Specific Granzyme B Induction as a Correlate of Protection

Zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania (L.) major infection is characterized by different clinical presentations which depend in part on the host factors. In attempt to investigate the impact of the host's immune response in the outcome of the disease, we conducted a prospective study of 453 individuals living in endemic foci of L. major transmission in Central Tunisia. Several factors were assessed at the baseline including (i) the presence of typical scars of ZCL, (ii) in vivo hypersensitivity reaction to leishmanin, and (iii) the in vitro release of granzyme B (Grz B) by peripheral blood mononuclear cells (PBMC) in response to stimulation with live L. major promastigotes. After one season of parasite's transmission, repeated clinical examinations allowed us to diagnose the new emerging ZCL cases. Heterogeneity was observed in terms of number of lesions developed by each individual as well as their size and spontaneous outcome, which led us to establish the parameter “severity of the disease.” The efficacy of the presence of typical ZCL scar, the leishmanin skin test (LST) positive reactivity and the high levels of Grz B (≥2 ng/ml), in the protection against the development of ZCL were 29, 15, and 22%, respectively. However, these factors were more efficient against development of intermediate or severe forms of ZCL. Levels of Grz B >2 ng/ml showed the best efficacy of protection (equals to 72.8%) against development of these forms of ZCL. The association of such parameter with the positivity of the LST exhibited a better efficacy (equals to 83.6%). In conclusion, our results support the involvement of Leishmania-specific cytotoxic cellular immune response in host protection against Leishmania-infection. This factor could be of great interest in monitoring the success of vaccination against human leishmaniasis.

Relapse, re-infection and mixed infections in tuberculosis disease

Tuberculosis (TB) disease can be characterized by genotypic and phenotypic complexity in Mycobacterium tuberculosis bacilli within a single patient. This microbiological heterogeneity has become an area of intense study due its perceived importance in drug tolerance, drug resistance and as a surrogate measure of transmission rates. This review presents a descriptive analysis of research describing the prevalence of mixed-strain TB infections in geographically distinct locations. Despite significant variation in disease burden and a rampant human immunodeficiency virus (HIV)-TB co-epidemic, there was no difference in the prevalence range of mixed infections reported in African countries when compared to the rest of the world. The occurrence of recurrent TB was associated with a higher prevalence of mixed-strain infections, but this difference was not reported as statistically significant. These interpretations were limited by differences in the design and overall size of the studies assessed. Factors such as sputum quality, culture media, number of repeated culture steps, molecular typing methods and HIV-infection status can affect the detection of mixed-strain infection. It is recommended that future clinical studies should focus on settings with varying TB burdens, with a common sample processing protocol to gain further insight into these phenomena and develop novel transmission blocking strategies.

Diagnosis of Helicobacter pylori recurrence: relapse or reinfection? Usefulness of molecular tools

BACKGROUND AND AIMS

Infection due to Helicobacter pylori causes many gastrointestinal diseases including peptic ulcers and gastric carcinoma. Their treatment and prevention depends on the successful eradication of H. pylori. However, even after a well-conducted treatment, H. pylori persists in about 10-30% of patients. Recurrent infections can correspond to relapse or to re-infection and require appropriate medical care. In this study, we explore retrospectively three clinical cases using molecular methods, and propose new guidelines for the diagnosis of recurrence.

MATERIAL AND METHODS

Ten colonies of H. pylori were selected from the primary culture of biopsy samples taken from the antrum and fundus for each patient. The genotype of each isolated colony was determined by analyzing the polymorphism of two housekeeping genes, hspA and glmM. The genome-wide composition of H. pylori strains was studied using in house macro-arrays designed.

RESULTS

Relapses were demonstrated by the stability of genotypes and the slight genetic variability of strains on macro-arrays. Two patients suffered from relapses, one and three years after H. pylori treatment. For the third patient, both the polymorphism of glmM and hspA genotypes and the diversity of CDSs identified on macro-arrays suggested that several episodes of re-infection occurred, 1-8 years after eradication.

CONCLUSION

For the three clinical cases, molecular methods allowed identifying the causes of recurrent infections. We suggest to study genotype to distinguish between relapse and re-infection in order to adapt the treatment and the follow-up of patients to the nature of recurrence.

Ranging behavior drives parasite richness: A more parsimonious hypothesis

Parasitism is a ubiquitous interspecific interaction that may play an important role in the evolution of hosts and parasites, molding many aspects of their behavior and ecology. Detecting behavioral changes of hosts infected with parasites is not a straightforward task. Extrapolating from individual-level responses to group-level decision-making is still a much more complex challenge. The ranging behavior of hosts that live in social groups is a good example. Many hypotheses of the cause-effect relationship between this behavior and parasite diversity and load have been proposed. For instance, Brockmeyer et al. [2015, Am. J. Primatol. 77:1036-1048] recently suggested that the richness of protozoan parasites influences the daily path length of free-ranging mandrills. We believe that this explanation for the relationship contains several implicit assumptions. Therefore, we offer an alternative, more parsimonious hypothesis in which daily path length is the driver of parasite richness rather than its consequence. Our hypothesis only assumes that ranging farther exposes animals to a richer parasite diversity. We discuss the data required to test these alternative hypotheses and recall empirical evidence and theoretical modeling results supporting or rejecting their assumptions. We also propose a model of the expected outcomes in terms of species richness, load, intensity of infection, and within-group community similarity of non-lethal environmentally transmitted parasites in social animal groups showing distinct patterns of range use. Am. J. Primatol. 78:923-927, 2016. © 2016 Wiley Periodicals, Inc.

Hepatitis C Virus Reinfection and Spontaneous Clearance of Reinfection--the InC3 Study

BACKGROUND

We aimed to characterize the natural history of hepatitis C virus (HCV) reinfection and spontaneous clearance following reinfection (reclearance), including predictors of HCV reclearance.

METHODS

Data were synthesized from the 9 prospective cohorts of the International Collaboration of Incident Human Immunodeficiency Virus and HCV in Injecting Cohorts study, which evaluated HCV infection outcomes among people who inject drugs. Participants with primary HCV infection were classified as having achieved viral suppression if they had negative results of at least 1 subsequent HCV RNA test. Those with positive results of an HCV RNA test following viral suppression were investigated for reinfection. Viral sequence analysis was used to identify reinfection (defined as detection of heterologous virus with no subsequent detection of the original viral strain).

RESULTS

Among 591 participants with acute primary HCV infection, 118 were investigated for reinfection. Twenty-eight participants were reinfected (12.3 cases/100 person-years; 95% confidence interval [CI], 8.5-17.8). Peak HCV RNA level was lower during reinfection than primary infection (P = .011). The proportion of individuals with reclearance 6 months after reinfection was 52% (95% CI, 33%-73%). After adjustment for study site, females with the IFNL4 (formerly IFNL3 and IL28B) rs12979860 CC genotype detected were more likely to have reclearance (hazard ratio, 4.16; 95% CI, 1.24-13.94; P = .021).

CONCLUSIONS

Sex and IFNL4 genotype are associated with spontaneous clearance after reinfection.

Clinical characteristics of relapses and re-infections in Clostridium difficile infection

The purpose of this study was to identify factors associated with relapses or re-infections in patients with recurring Clostridium difficile infections (CDIs). From September 2008 to January 2012, cases with two or more isolates from consecutive CDI episodes were included. PCR-ribotyping and multilocus variable-number tandem-repeat analysis were performed using paired isolates. Among 473 patients, 68 (14.4%) experienced one to five recurrences. Fifty-one of these with two or more isolates from consecutive CDI episodes were included in the study; 25 (49%) were classified as relapses and 26 (51%) as re-infections. Recurrence interval was shorter in the relapse group (26.0 versus 67.5 p 0.001), but more patients in the re-infection group were hospitalized during recurrence interval (53.8% versus 8.0%, p<0.001). Relapse rates in infections by ribotype 017, ribotype 018 and other ribotypes were 63.6%, 63.6% and 22.2%, respectively (p 0.274, p 0.069, and p 0.005). In multivariate logistic regression, infections by ribotypes 017 and 018 were associated with CDI relapse (OR 4.77, 95% CI 1.02-22.31, p 0.047; OR 11.49, 95% CI 2.07-63.72, p 0.005). Conversely, admission during recurrence interval lowered the risk of relapse (OR 0.044, 95% CI 0.006-0.344, p 0.003). In conclusion, relapse was more likely when infection was caused by PCR ribotypes 017 and 018.

A cohort study of Chlamydia trachomatis treatment failure in women: a study protocol

BACKGROUND

Chlamydia trachomatis is the most commonly diagnosed bacterial sexually transmitted infection in the developed world and diagnosis rates have increased dramatically over the last decade. Repeat infections of chlamydia are very common and may represent re-infection from an untreated partner or treatment failure. The aim of this cohort study is to estimate the proportion of women infected with chlamydia who experience treatment failure after treatment with 1 gram azithromycin.

METHODS/DESIGN

This cohort study will follow women diagnosed with chlamydia for up to 56 days post treatment. Women will provide weekly genital specimens for further assay. The primary outcome is the proportion of women who are classified as having treatment failure 28, 42 or 56 days after recruitment. Comprehensive sexual behavior data collection and the detection of Y chromosome DNA and high discriminatory chlamydial genotyping will be used to differentiate between chlamydia re-infection and treatment failure. Azithromycin levels in high-vaginal specimens will be measured using a validated liquid chromatography-tandem mass spectrometry method to assess whether poor azithromycin absorption could be a cause of treatment failure. Chlamydia culture and minimal inhibitory concentrations will be performed to further characterize the chlamydia infections.

DISCUSSION

Distinguishing between treatment failure and re-infection is important in order to refine treatment recommendations and focus infection control mechanisms. If a large proportion of repeat chlamydia infections are due to antibiotic treatment failure, then international recommendations on chlamydia treatment may need to be re-evaluated. If most are re-infections, then strategies to expedite partner treatment are necessary.

Frequency and implications of HIV superinfection

HIV superinfection occurs when an individual with HIV is infected with a new distinct HIV viral strain. Superinfection has been reported throughout the world, and studies have recorded incidence rates of 0-7·7% per year. Use of next-generation sequencing has improved detection of superinfection, which can be transmitted by injecting drug use and sexual intercourse. Superinfection might have incidence rates comparable to those of initial HIV infection. Clinicians should encourage safe sexual and injecting drug use practices for HIV-infected patients because superinfection has detrimental effects on clinical outcomes and could pose a concern for large-scale antiretroviral treatment plans. The occurrence of superinfection has implications for vaccine research, since it seems initial HIV infection is not fully protective against a subsequent infection. Additional collaborative research could benefit care of patients and inform future vaccine design.