High Attack Rate Research Articles

Coronavirus Disease 2019 Outbreak in a Psychiatric Closed Ward: What We Have to Learn.

An outbreak of COVID-19 with an extremely high attack rate happened in a psychiatric closed ward. One hundred two (98.1%) out of 104 patients were diagnosed with COVID-19 between February 20th and 26th, 2020, most of whom were with schizophrenia. Facility factors (such as multi-share rooms, closed windows, and absence of alcohol hand rubs), along with chronic medical conditions, and difficulty to explain symptoms for psychiatric patients might have contributed to the high attack rate. To overcome these hurdles, efficient ventilating with filtration system in psychiatric facilities, strict access control to closed wards, and prompt response to febrile patients could prevent nosocomial outbreak. We must consider that the influx of COVID-19 into a closed ward could cause an extremely high attack rate, and have to be vigilant against COVID-19 in psychiatric wards.

A large food-borne outbreak of campylobacteriosis in kindergartens and primary schools in Pescara, Italy, May-June 2018.

Introduction. In May-June 2018, an outbreak of campylobacteriosis involved students and school staff from kindergartens and primary schools in Pescara, southern Italy.Aim. We present details of the epidemiological and microbiological investigation, and the findings of the analytical study, as well as the implemented control measures.Methodology. To identify possible risk factors associated with the observed outbreak, a case control study was conducted using a questionnaire to collect information on the date of symptoms onset, type and duration of symptoms, type of healthcare contact, school attendance, and food items consumed at school lunches during the presumed days of exposure. Attack rates were calculated for each date and school. Logistic regression models were used to estimate the odds ratios of being a case and the odds of illness by food items consumed, respectively. Moreover, we carried out a comparative genomic analysis using whole genome multilocus sequence typing (wgMLST) of Campylobacter jejuni strains isolated during the outbreak investigation to identify the source of the outbreak.Results. Overall, 222 probable cases from 21 schools were identified, and C. jejuni was successfully isolated from 60 patients. The meals in the schools involved were provided by two cooking centres managed by a joint venture between two food companies. Environmental and food sampling, epidemiological and microbiological analyses, as well as a case control study with 176 cases and 62 controls from the same schools were performed to identify the source of the outbreak. The highest attack rate was recorded among those having lunch at school on 29 May (7.8 %), and the most likely exposure was 'caciotta' cheese (odds ratio 2.40, 95 % confidence interval 1.10-5.26, P=0.028). C. jejuni was isolated from the cheese, and wgMLST showed that the human and cheese isolates belonged to the same genomic cluster, confirming that the cheese was the vehicle of the infection.Conclusion. It is plausible that a failure of the pasteurization process contributed to the contamination of the cheese batches. Timely suspension of the catering service and summer closure of the schools prevented further spread.

COVID-19 within a large UK prison with a high number of vulnerable adults, march to june 2020: An outbreak investigation and screening event

ObjectiveTo describe the public health response to COVID-19 within a large prison with a high number of clinically vulnerable residents. DesignAn outbreak investigation was undertaken among all residents and staff. A screening event involved nose and throat swab samples from residents and staff, examined by polymerase chain reaction (PCR). An electronic questionnaire regarding risk factors was distributed to staff. Results58 residents out of 1,156 (5.0%, 95% CI: 3.8 – 6.3) and 129 staff out of 510 (25.3%, 95% CI: 21.5 – 29.1) displayed COVID-19 symptoms, including six and eight confirmed, respectively. Residents reported cough symptoms with no fever (29.3%), followed by a cough and fever (15.5%). 62.1% of symptomatic residents were 50 years or older, placing them in the group at risk for severe COVID-19 disease. Wing I had the highest attack rate (12.5%). 1,063 individuals were swabbed during the 5-day screening event, and all had negative swab results. ConclusionThe findings were consistent with the hypothesis of a propagating outbreak with decreasing incidence since the peak date of onset. COVID-19 transmission within a high-risk setting was quickly contained, and an explosive outbreak was prevented through a multi-agency public health response.

Attack rate in Manaus

Coronovirus Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) incidence peaked in Manaus, Brazil, in May 2020 with a devastating toll on the city's inhabitants, leaving its health services shattered and cemeteries overwhelmed. Buss et al. collected data from blood donors from Manaus and Sao Paulo, noted when transmission began to fall, and estimated the final attack rates in October 2020 (see the Perspective by Sridhar and Gurdasani). Heterogeneities in immune protection, population structure, poverty, modes of public transport, and uneven adoption of nonpharmaceutical interventions mean that despite a high attack rate, herd immunity may not have been achieved. This unfortunate city has become a sentinel for how natural population immunity could influence future transmission. Events in Manaus reveal what tragedy and harm to society can unfold if this virus is left to run its course. Science , this issue p. [288][1]; see also p. [230][2] [1]: /lookup/doi/10.1126/science.abe9728 [2]: /lookup/doi/10.1126/science.abf7921

Should high household attack rates change public health polices?

Should high household attack rates change public health polices?

COVID-19 Outbreaks Following Full Reopening of Primary and Secondary Schools in England: Retrospective, Cross-Sectional National Surveillance

Background: The full reopening of schools in September 2020 was associated with an increase in COVID-19 cases and outbreaks in educational settings across England. Methods: Primary and secondary schools reporting an outbreak (≥2 laboratory-confirmed cases within 14 days) to Public Health England (PHE) between 31 August and 18 October 2020 were contacted to complete an online questionnaire. Interpretation: There were 969 primary (n=450) and secondary school outbreaks (n=519) reported to PHE, representing 3% of primary schools and 15% of secondary schools in England. Of the 369 schools contacted, 190 geographically-representative schools completed the questionnaire; 2,425 cases were reported. Secondary school students (1.20%; 95%CI, 1.13-1.28%) had higher attack rates than primary school students (0.84%; 95%CI, 0.75-0.94%). Outbreaks were larger and across more year groups in secondary schools than in primary schools. When an outbreak occurred, attack rates were higher in staff (926/19,083; 4.85%; 95%CI, 4.55-5.17%) than students, especially among primary school teaching staff (9.81%; 95%CI, 8.90-10.82%) compared to secondary school teaching staff (3.97%; 95%CI, 3.79-5.69%). Staff represented 59% (471/799) of cases in primary school outbreaks and 27% (410/1515) in secondary schools (PConclusions: Secondary schools were more likely to be affected by a COVID-19 outbreak than primary schools and to experience larger outbreaks across multiple school years. The higher attack rate among teaching staff during an outbreak suggests that additional protective measures may be needed. Funding: PHE

Seroprevalence of Anti-Sars-Cov-2 Antibodies in Colombia, 2020: A Population-Based Study

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to cause very high morbidity and mortality throughout Latin American countries. However, few population-based seroprevalence surveys have been conducted to quantify attack rates and characterize drivers of transmission.Methods: We conducted a population-based cross-sectional study to assess the seroprevalence of antibodies against SARS-CoV-2 in ten cities in Colombia between September and December, 2020. The study involved multi-stage cluster sampling at each city. Participants provided a serum sample and answered a demographic and risk factor questionnaire. Prior infection by SARS-CoV-2 was ascertained using the "SARS-CoV-2 Total (COV2T) Advia Centaur - Siemens" chemiluminescence assay.Findings: A total of 17863 participants from 7075 households participated in the study. Seroprevalence varied substantially between cities, ranging from 21% (95%CI 16-25%) in Medellín to 78% (95%CI 65-91%) in Guapi. There were no differences in seroprevalence by sex, but seropositivity was lower in adults 60 years or older and higher in certain ethnic groups. There was substantial heterogeneity in seroprevalence within cities, driven to a large extent by a strong association between socio-economic stratum and seropositivity.Interpretation: Colombia has been one of the Latin American countries most affected by the COVID-19 pandemic. This study documented very high attack rates in several Colombian cities by the end of 2020 and identified key drivers of heterogeneities including ethnicity and socio-economic stratum. Few studies of seroprevalence of SARS-CoV-2 have been conducted in Latin America, and therefore this study contributes to the fundamental understanding of the pandemic in the region.

An epidemiological investigation of the 2019 suspected pertussis outbreak in northwestern Nigeria.

Introduction:In 2019, we investigated the profile of the cases and controls and the determinants of pertussis transmission in Kebbi State, Northwestern Nigeria, to inform better immunization and surveillance strategies.Methods:Community-based unmatched case–control study and review of the 2019 pertussis routine surveillance data in the affected settlements in the state were conducted. A total of 52 suspected cases of pertussis and 107 control from two local government areas in Kebbi State were recruited. Data were analyzed using descriptive and inferential statistics.Results:The highest attack rate was observed among between 1- and 4-year age group followed by children less than 1-year old, and the least attack rate was among those above 15 years. The overall attack rate and the case fatality rate were 2.10% and 0.10%, respectively. A higher attack rate was observed among women, whereas the case fatality rate was more among males. From the community survey, we observed that the cases were less likely to have pertussis vaccination history (adjusted odds ratio = 0.28, 95% confidence interval = 0.11–0.74) compared with the controls. Knowing pertussis prevention methods were found protective for pertussis transmission (adjusted odds ratio = 0.14, 95% confidence interval = 0.04–0.45).Conclusion:This study showed the vulnerability of children under 5 years, especially under 1 year, to vaccine-preventable diseases in rural populations, where “real” immunization coverage is sub-optimal, and the dominant socio-demographic factors are supportive of disease transmission. We found immunization and knowledge of the preventive measures to be protective against pertussis outbreaks. Therefore, routine immunization services must be intensified to improve coverage and prevent future pertussis outbreak(s).

Acute diarrheal disease outbreak in Muzaffarpur Village, Chandauli District, Uttar Pradesh, India.

Acute diarrheal disease (ADD) outbreaks frequently occur in the Gangetic plains of Uttar Pradesh, India. In August 2017, Muzaffarpur village, Uttar Pradesh, reported an ADD outbreak. Outbreak investigation was conducted to find out the epidemiology and to identify the risk factors. A 1:1 area-matched case-control study was conducted. Suspected ADD case was defined as ≥3 loose stools or vomiting within 24 h in a Muzaffarpur resident between August 7 and September 9, 2017. A control was defined as an absence of loose stools and vomiting in a resident between August 7 and September 9, 2017. A matched odds ratio (mOR) with 95% confidence intervals (CIs) was calculated. Drinking water was assessed to test for the presence of any contamination. Stool specimens were tested for Vibrio cholerae, and water samples were also tested for any fecal contamination and residual chlorine. Among 70 cases (female = 60%; median age = 12 years, range = 3 months-70 years), two cases died and 35 cases were hospitalized. Area-A in Muzaffarpur had the highest attack rate (8%). The index case washed soiled clothes at well - A1 1 week before other cases occurred. Among 67 case-control pairs, water consumption from well-A1 (mOR: 43.00; 95% CI: 2.60-709.88) and not washing hands with soap (mOR: 2.87; 95% CI: 1.28-6.42) were associated with illness. All seven stool specimens tested negative for V. cholerae. All six water samples, including one from well-A1, tested positive for fecal contamination with <0.2 ppm of residual chlorine. This outbreak was associated with consumption of contaminated well water and hand hygiene. We recommended safe water provision, covering wells, handwashing with soap, access to toilets, and improved laboratory capacity for testing diarrheal pathogens.

Prey preference of top predators manipulates the functioning and stability of multi-trophic ecosystems

The relationship between biodiversity and ecosystem functioning, and the mechanisms underpinning the food web stability, have been intensively investigated in ecological research. The ubiquities of generalists in natural food webs and its important role in dictating these ecosystem properties have been generally recognized. However, how competition between multiple top predators shape these ecosystem properties and determine the success of invasive predators remain largely unexplored. Here, we use a well-developed food web model to investigate the effects of prey preference of top predators on ecosystem functioning and food web stability in both local and invasive conditions. We design several modeling scenarios to mimic combinations of different types of top predators (specialist/generalist) and their origins (local/invasive). Our model theoretically shows that lower exploitation competition for prey between top predators (with distinct prey preferences featured by higher attack rates) would be beneficial for the ecosystem functioning and food web stability. We also demonstrate that the success of top predator invasion depends on the prey preference of both local and invasive top predators. Sensitivity analysis on the model further supports our findings. Our results highlight the importance of prey preference of multiple top predators in manipulating the properties of multi-trophic ecosystems. Our findings may have important implications because the current ongoing global changes profoundly change the phenology of many biological systems and create trophic mismatch, which may manipulate prey preference of top predators and in turn deteriorate ecosystem functioning and food web stability.

Dynamics of transmission of COVID-19 cases and household contacts: A prospective cohort study

Objective: To study the transmission dynamics of coronavirus disease 2019 (COVID-19) among 101 confirmed cases and their 387 household contacts and to determine risk factors associated with secondary attack among the household contacts.Methods: A prospective cohort study was conducted from January 1st 2021 to February 28th 2021, among 101 SARS-CoV-2 cases and 387 household contacts who were followed up for 14 days from the last day of contact with the index case of COVID-19. The dynamics of disease transmission was estimated, and factors affecting transmission risk were analyzed. Besides, the association between various factors and household secondary attack rate was determined.Results: The median incubation period was found to be 5 days, and the observed reproductive number (R) was found to be 1.63 (95% CI: 1.28-1.98). The mean household secondary attack rate was 40.7%. Contacts with comorbidities like diabetes mellitus, hypertension, dyslipidemia, and hypothyroidism had significantly higher attack rates (P<0.05).Conclusions: As new variants of SARS-CoV-2 emerges, it is crucial to know the trasmission dynamics. This study shows a high secondary attack rate of COVID-19 among household contacts that must be closely monitored.

COVID-19 outbreak at a reception centre for asylum seekers in Espoo, Finland

Background shared accommodation may increase the risk of SARS-CoV-2 transmission. In April 2020, an increasing number of asylum seekers at a reception centre in Espoo, Finland presented with COVID-19 despite earlier implementation of preventive measures. We decided to screen the entire population of the centre for SARS-CoV-2.Methods we offered nasopharyngeal swab collection and SARS-CoV-2 real-time polymerase chain reaction (RT-PCR) analysis to the centre's clients. Symptoms were recorded at the time of diagnostic sample collection using electronic forms and followed up for two weeks through phone interviews and a review of medical records.Findings 260 clients were screened. Of them, 96 (37%) were found positive for SARS-CoV-2 and isolated. The high attack rate prompted the local public health authority to set the other clients in quarantine for 14 days to prevent further spread. Of the positive cases, 61 (64%) reported having had symptoms at the time of the screening or one week prior. Of the 35 initially asymptomatic individuals, 12 developed symptoms during follow-up, while 23 (or 18% of all screened SARS-CoV-2 positive clients) remained asymptomatic. No widespread transmission of COVID-19 was detected after the quarantine was lifted.Interpretation in this large COVID-19 outbreak, voluntary mass screening provided valuable information about its extent and helped guide the public health response. Comprehensive quarantine and isolation measures were likely instrumental in containing the outbreak.Funding Finnish Institution for Health and Welfare, Finnish Immigration Agency, City of Espoo

Community transmission of rotavirus infection in a vaccinated population in Blantyre, Malawi: a prospective household cohort study

Rotavirus vaccine effectiveness is reduced among children in low-income countries. Indirect (transmission-mediated) effects of rotavirus vaccine might contribute to the total population effect of vaccination. We aimed to examine risk factors for transmission of rotavirus to household contacts in Blantyre, Malawi, and estimated the effectiveness of rotavirus vaccine in preventing transmission of infection to household contacts. In this prospective household cohort study, we recruited children born after Sept 17, 2012, and aged at least 6 weeks (vaccine-eligible children) with acute rotavirus gastroenteritis and their household contacts, in four government health facilities in Blantyre, Malawi. Clinical data, a bulk stool sample, and 1-2 mL of serum were collected from case children at presentation. Clinical data and stool samples were also prospectively collected from household contacts over 14 days from presentation. A single stool sample was collected from control households containing asymptomatic children who were frequency age-matched to case children. Samples were tested for rotavirus using semi-quantitative real-time PCR and for anti-rotavirus IgA using a semi-quantitative sandwich ELISA. Risk factors for household transmission of rotavirus infection and clinical disease, including disease severity and faecal shedding density, were identified using mixed effects logistic regression. Vaccine effectiveness against transmission was estimated as 1 minus the ratio of secondary attack rates in vaccinated and counterfactual unvaccinated populations, using vaccine effectiveness estimates from the associated diarrhoeal surveillance platform to estimate the counterfactual secondary attack rate without vaccination. Between Feb 16, 2015, and Nov 11, 2016, we recruited 196 case households (705 members) and 55 control households (153 members). Household secondary attack rate for rotavirus infection was high (434 [65%] of 665 individuals) and secondary attack rate for clinical disease was much lower (37 [5%] of 698). Asymptomatic infection in control households was common (40 [28%] of 144). Increasing disease severity in an index child (as measured by Vesikari score) was associated with increased risk of transmission of infection (odds ratio 1·17 [95% CI 1·06-1·30) and disease (1·28 [1·08-1·52]) to household contacts. Estimated vaccine effectiveness against transmission was 39% (95% CI 16-57). Rotavirus vaccine has the potential to substantially reduce household rotavirus transmission. This finding should be considered in clinical and health economic assessments of vaccine effectiveness. Wellcome Trust, US National Institutes of Health, and US National Institute of Allergy and Infectious Diseases.

50 Years Ago in TheJournalofPediatrics: The Status of Measles and Rubella Immunization in the United States

Krugman S. Present status of measles and rubella immunization in the United States: a medical progress report. J Pediatr 1971;78:1-16. In 1971, the challenge with the relatively new measles and rubella vaccines was determining “which one” was best. Multiple strains of both live attenuated and inactivated vaccines were being trialed. Thus, Dr Saul Krugman reviewed the state of the vaccines less than 10 years after the first measles vaccine and 2 years after the first rubella vaccine. After assessing the data from numerous serologic studies from as far away as the Faroe Islands, Krugman concluded that the 2 measles vaccines (Edmonston B and Schwartz) were effective and that one dose should provide long-term immunity to measles for 98% of children. At the time, Krugman could not have predicted how health disparities and antiscience beliefs would impact vaccine delivery. Between 1989 and 1990, measles cases surged from 3700 to 18 193, with outbreaks fueled by unvaccinated preschool-aged children of racial and ethnic minority groups living in inner-city areas.1Atkinson W.L. Orenstein W.A. Krugman S. The resurgence of measles in the US: 1989-1990.Annu Rev Med. 1992; 43: 451-463Crossref PubMed Scopus (100) Google Scholar In addition, that year an outbreak with high fatality rates occurred in Philadelphia in an unvaccinated church community.2Rodgers D.V. Gindler J.S. Atkinson W.L. Markowitz L.E. High attack rates and case fatality during a measles outbreak in groups with religious exemption to vaccination.Pediatr Infect Dis J. 1993; 12: 288-292Crossref PubMed Scopus (37) Google Scholar These outbreaks led to the current 2-dose series of the measles, mumps, and rubella vaccine (MMR) and a decline in the incidence of measles. Unfortunately, over the past decade with the promulgation of a discredited study linking MMR to autism and the growing social media presence of antivaccine misinformation, the US incidence rose from 43 cases in 2007 to 1282 cases in 2019.3Centers for Disease Control and PreventionMeasles Cases and Outbreaks.https://www.cdc.gov/measles/cases-outbreaks.htmlDate accessed: July 6, 2020Google Scholar The pediatric community is faced with again combating a once-vanquished, deadly disease, but in the midst of a pandemic and a climate of disinformation and antiscience sentiment. Dr. Scott Krugman is Dr. Saul Krugman's eldest grandson and is a third generation pediatrician.

Refinement of the CS6-expressing enterotoxigenic Escherichia coli strain B7A human challenge model: A randomized trial

BackgroundHuman challenge models for enterotoxigenic Escherichia coli (ETEC) facilitate vaccine down-selection. The B7A (O148:H28 CS6+LT+ST+) strain is important for vaccine development. We sought to refine the B7A model by identifying a dose and fasting regimen consistently inducing moderate-severe diarrhea.MethodsAn initial cohort of 28 subjects was randomized (1:1:1:1) to receive B7A following an overnight fast at doses of 108 or 109 colony forming units (cfu) or a 90-minute fast at doses of 109 or 1010 cfu. A second cohort included naïve and rechallenged subjects who had moderate-severe diarrhea and were given the target regimen. Immune responses to important ETEC antigens were assessed.ResultsAmong subjects receiving 108 cfu of B7A, overnight fast, or 109 cfu, 90-minute fast, 42.9% (3/7) had moderate-severe diarrhea. Higher attack rates (71.4%; 5/7) occurred in subjects receiving 109 cfu, overnight fast, or 1010 cfu, 90-minute fast. Upon rechallenge with 109 cfu of B7A, overnight fast, 5/11 (45.5%) had moderate-severe diarrhea; the attack rate among concurrently challenge naïve subjects was 57.9% (11/19). Anti-CS6, O148 LPS and LT responses were modest across all groups.ConclusionsAn overnight fast enabled a reduction in the B7A inoculum dose; however, the attack rate was inconsistent and protection upon rechallenge was minimal.

Measles outbreak investigation in Kambia District, Sierra Leone-2018

Background: Measles, an acute highly infectious viral disease, remains one of the leading causes of childhood morbidity and mortality worldwide. Despite the availability of safe and effective vaccines, measles cases have been reported in Sierra Leone. On 29 October 2018, the Kambia district health management team was notified of a suspected measles outbreak. On 1 November 2019, we investigated the outbreak to confirm the diagnosis, assess the magnitude, identify potential risk factors, and institute control measures. Methods and materials: We defined a suspected case as any person with fever and maculopapular rash in Kambia district from 1st October 2018 and a probable case as any suspected case with epidemiologic link to a laboratory confirmed case. We reviewed medical records, interviewed parents, patients and collected blood samples for measles confirmation. We collected patients’ demographic, clinical and exposure history. We conducted active case search and needs assessment for measles reactive mass vaccination in the community. We conducted social mobilization and risk communication. Results: A total of 91 cases (14 laboratory-confirmed and 77 probable cases) with no deaths reported. The overall Attack Rate (AR) was 24.2/100,000 persons, with the highest AR (119.6/100,000 persons) among the 6–11 months age group. The median age was 24.5 months (range 4–348), and 48 (56%) were females. Four out of seven chiefdoms were affected and Gibnleh-Dixon chiefdom was the most affected (AR = 274.9/100,000). The first four detected cases had travel history to the neighboring Republic of Guinea, where there was a confirmed measles outbreak, and three of the four affected villages are close to the border. The district administrative vaccination coverage was 87%, however, of the total 84 eligible cases, only two had vaccination cards. Conclusion: A measles outbreak was confirmed in Kambia district which shares a border with Guinea. The importation of measles cases in a susceptible community might have contributed to the spread of measles in the affected chiefdoms. A reactive mass vaccination targeting children aged six months to 15 years was conducted and achieved coverage of 100.8%. We recommended strengthening routine immunization through increased outreach vaccination sessions to communities, supplementary vaccination and to strengthen cross border surveillance and response framework.

Successive epidemic waves of cholera in South Sudan between 2014 and 2017: a descriptive epidemiological study

SummaryBackgroundBetween 2014 and 2017, successive cholera epidemics occurred in South Sudan within the context of civil war, population displacement, flooding, and drought. We aim to describe the spatiotemporal and molecular features of the three distinct epidemic waves and explore the role of vaccination campaigns, precipitation, and population movement in shaping cholera spread in this complex setting.MethodsIn this descriptive epidemiological study, we analysed cholera linelist data to describe the spatiotemporal progression of the epidemics. We placed whole-genome sequence data from pandemic Vibrio cholerae collected throughout these epidemics into the global phylogenetic context. Using whole-genome sequence data in combination with other molecular attributes, we characterise the relatedness of strains circulating in each wave and the region. We investigated the association of rainfall and the instantaneous basic reproduction number using distributed lag non-linear models, compared county-level attack rates between those with early and late reactive vaccination campaigns, and explored the consistency of the spatial patterns of displacement and suspected cholera case reports.FindingsThe 2014 (6389 cases) and 2015 (1818 cases) cholera epidemics in South Sudan remained spatially limited whereas the 2016–17 epidemic (20 438 cases) spread among settlements along the Nile river. Initial cases of each epidemic were reported in or around Juba soon after the start of the rainy season, but we found no evidence that rainfall modulated transmission during each epidemic. All isolates analysed had similar genotypic and phenotypic characteristics, closely related to sequences from Uganda and Democratic Republic of the Congo. Large-scale population movements between counties of South Sudan with cholera outbreaks were consistent with the spatial distribution of cases. 21 of 26 vaccination campaigns occurred during or after the county-level epidemic peak. Counties vaccinated on or after the peak incidence week had 2·2 times (95% CI 2·1–2·3) higher attack rates than those where vaccination occurred before the peak.InterpretationPandemic V cholerae of the same clonal origin was isolated throughout the study period despite interepidemic periods of no reported cases. Although the complex emergency in South Sudan probably shaped some of the observed spatial and temporal patterns of cases, the full scope of transmission determinants remains unclear. Timely and well targeted use of vaccines can reduce the burden of cholera; however, rapid vaccine deployment in complex emergencies remains challenging.FundingThe Bill & Melinda Gates Foundation.

E. coli O157:H7 outbreak and hemolytic uremic syndrome in a day care center in Brazil

Background: Shiga toxin-producing Escherichia coli O157:H7 (STEC-O157: H7) infection is related to major outbreaks and serious diseases such as hemolytic uremic syndrome (HUS). In March 2019, a gastroenteritis outbreak occurred in the day care center of Vila Velha-Brazil, and a death occurred by HUS. Epidemiological investigation was conducted to identify the agent involved and source of infection. Methods and materials: A descriptive study. Cases were: children or employees who presented diarrhea or vomiting from March 1st to April 5th, 2019. A semi-structured questionnaire was applied. The rate attack of cases per class was calculated. Stool samples were collected from the cases and from water reservoir, kitchen tap reducer, water toy, water and food. Laboratory techniques used: culture, Polymerase chain reaction (PCR), and pulsed field electrophoresis- PFGE. Results: There were 24 cases of diarrhea, of these two (79,0%) were children, five (20,9%) employees. The cases reduced by 92% after the suspension of day care activities in March 26th. The 2-year-old class had the highest attack rate (40,0%) and there were no case in the 4-year-old class. Bloody diarrhea was reported in five (21,0%), abdominal pain nine (38,0%), vomiting eight (33,0%), and three (12,0%) evolved to HUS, with one death (33% lethality by SHU). STEC-O157: H7 was detected in two children who had bloody diarrhea (one with HUS) and in the water tap reducer. The PFGE analysis identified that, the genetic homology between case strains was 90% and the genetic similarity between the cases and the water tap reducer was 64,0%. Conclusion: A gastroenteritis outbreak occurred in the day care center involving the EHEC O157: H7 strain. It is suggested that E. coli was introduced into the day care center by an infected person, spreading the outbreak, maintained by person-to-person transmission, stop the school activities and professionals guide about the characteristics of the disease helped in minimizing the severity of cases. It was recommended to guide teachers/staff about how to prevent fecal-oral transmission diseases, and to monitor water quality in the day care center.

Small-Molecule Inhibitors of Chikungunya Virus: Mechanisms of Action and Antiviral Drug Resistance.

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that has spread to more than 60 countries worldwide. CHIKV infection leads to a febrile illness known as chikungunya fever (CHIKF), which is characterized by long-lasting and debilitating joint and muscle pain. CHIKV can cause large-scale epidemics with high attack rates, which substantiates the need for development of effective therapeutics suitable for outbreak containment. In this review, we highlight the different strategies used for developing CHIKV small-molecule inhibitors, ranging from high-throughput cell-based screening to in silico screens and enzymatic assays with purified viral proteins. We further discuss the current status of the most promising molecules, including in vitro and in vivo findings. In particular, we focus on describing host and/or viral targets, mode of action, and mechanisms of antiviral drug resistance and associated mutations. Knowledge of the key molecular determinants of drug resistance will aid selection of the most promising antiviral agent(s) for clinical use. For these reasons, we also summarize the available information about drug-resistant phenotypes in Aedes mosquito vectors. From this review, it is evident that more of the active molecules need to be evaluated in preclinical and clinical models to address the current lack of antiviral treatment for CHIKF.

Neutralizing Antibodies Correlate with Protection from SARS-CoV-2 in Humans during a Fishery Vessel Outbreak with a High Attack Rate.

The development of vaccines against SARS-CoV-2 would be greatly facilitated by the identification of immunological correlates of protection in humans. However, to date, studies on protective immunity have been performed only in animal models and correlates of protection have not been established in humans. Here, we describe an outbreak of SARS-CoV-2 on a fishing vessel associated with a high attack rate. Predeparture serological and viral reverse transcription-PCR (RT-PCR) testing along with repeat testing after return to shore was available for 120 of the 122 persons on board over a median follow-up of 32.5 days (range, 18.8 to 50.5 days). A total of 104 individuals had an RT-PCR-positive viral test with a cycle threshold (CT ) of <35 or seroconverted during the follow-up period, yielding an attack rate on board of 85.2% (104/122 individuals). Metagenomic sequencing of 39 viral genomes suggested that the outbreak originated largely from a single viral clade. Only three crew members tested seropositive prior to the boat's departure in initial serological screening and also had neutralizing and spike-reactive antibodies in follow-up assays. None of the crew members with neutralizing antibody titers showed evidence of bona fide viral infection or experienced any symptoms during the viral outbreak. Therefore, the presence of neutralizing antibodies from prior infection was significantly associated with protection against reinfection (Fisher's exact test, P = 0.002).