scholarly journals Nationwide outbreak of Salmonella serotype Kedougou associated with infant formula, Spain, 2008

2010 ◽  
Vol 15 (22) ◽  
Author(s):  
J Rodríguez-Urrego ◽  
S Herrera-León ◽  
A Echeita-Sarriondia ◽  
P Soler ◽  
F Simon ◽  
...  
Keyword(s):  
Risk Factors ◽  
Infant Formula ◽  
Ad Hoc ◽  
Univariate Analysis ◽  
Medical Practitioner ◽  
Case Definition ◽  
Control Measures ◽  
Formula Milk ◽  
Medical Practitioners ◽  
One Year

On 5 August 2008, the National Centre of Microbiology in Madrid, Spain, notified an increase in Salmonella Kedougou isolations compared to 2007, with 21 cases including 19 children under one year of age. Active case finding and a matched case-control study were carried out to confirm this increase, identify source, transmission mode and risk factors in order to implement control measures. Cases were defined as any child under one year of age with S. Kedougou isolated since 1 January 2008, and were matched for age, sex, medical practitioner and diagnosis week with controls who were selected among patients of the cases' medical practitioners. An ad hoc questionnaire was completed for cases and controls and a univariate analysis was conducted to identify risk factors. We found 42 isolates from 11 of the 19 Spanish Regions. Completed questionnaires were available for 39 of 42 patients identified; 31 were children under one year of age and fulfilled the case definition. The median age of the 31 cases was 4.3 months and 13 were male. Main symptoms were diarrhoea (n=31) and fever (n=13). Ten cases required hospitalisation. All 31 cases had consumed infant formula milk of Brand A which was associated with illness in the univariate analysis (exact matched odds ratio: 74.92; 95% confidence interval: 12.89-∞). All patient isolates showed indistinguishable pulsed-field gel electrophoresis and antimicrobial susceptibility patterns. Five milk samples from three cases' households were negative for Salmonella. Our results suggest that Brand A was the transmission vehicle of S. Kedougou in the outbreak that occurred in Spain between January and August 2008. Food safety authorities recalled five batches of Brand A milk on 26 August 2008. No further cases have been detected as of 15 September 2009.

scholarly journals Cutaneous Leishmaniasis Outbreak Investigation in Hajjah Governorate, Yemen, 2018 (Preprint)

2021 ◽  
Author(s):  
Abdulkareem Ali Nassar ◽  
Mahmood Abdulrazzaq ◽  
Ali Hamoud Almahaqri ◽  
Mohammed Abdullah Al-Amad ◽  
Abulwahed Abduljabbar Al Serouri ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cutaneous Leishmaniasis ◽  
Female Gender ◽  
Skin Lesions ◽  
Case Definition ◽  
Control Measures ◽  
Age Group ◽  
Related Factors ◽  
One Year ◽  
Definition Of

BACKGROUND On 23 July 2018, Hajjah governorate surveillance officer notified Ministry of Health about increased number of cutaneous leishmaniasis (CL) cases in Bani-Oshb, Kuhlan district, Hajjah governorate. On 24 July 2018, Yemen Field Epidemiology Training Program sent a team to perform investigation. OBJECTIVE To describe a CL outbreak in Hajjah governorate and determine its risk factors. METHODS A descriptive study followed by a case-control study were conducted. Cases were defined as any person who met the suspected or confirmed case definition of WHO and live in Bani-Oshb sub-district during the period August 2017 - July 2018. Controls were defined as any person living for at least one year in Bani-Oshb without new or old skin lesions. Crude or adjusted Odd Ratios (cOR or aOR) with 95% Confidence Interval (CI) was used to test the significance of the association. RESULTS Thirty cases with leishmaniasis were found in Bani-Oshb sub-district during the period August 2017 - July 2018. Twenty-three percent of patients were younger than 5 years, 57% aged 5-14 year, 57% were females and 77% of cases had one lesion. The attack rate was 7 per 1000 population in the age group < 15 year and 1 per 1000 population in the age group ≥15 year. On bi-variate analysis the following factors were significantly associated with CL: female gender (cOR 5.2, 95% CI 1.7–16.5), malnutrition (cOR 5.2, 95% CI 1.7–16.5), not using bed net (cOR 14.5, 95% CI 1.7–122.4), poor house lightening (cOR 6.4, 95% CI 2.1–19.7), poor house hygiene (cOR 11.2, 95% CI 3.1–40.7), and poor sanitation (cOR 14.5, 95% CI 1.7–122.4), living in houses without windows net (OR 5.2, 95% CI 1.3–21.2), plantation around the house (cOR 6.5, 95% CI 2.1–20.5), animals barn inside or close to the house (cOR 9.3, 95% CI 1.9–46.7), raising animals (cOR 8.1, 95% CI 1.6–40.7) and having animal’s dung in or near the house (cOR 6.8, 95% CI 1.7–27.7). The following risk factors remained significant after application of multivariate stepwise analysis: female gender (aOR 22.7, 95% CI 1.6–320.5), malnutrition (aOR 17.2, 95% CI 1.3–225.8), poor house hygiene (aOR 45.6, 95% CI 2.5–846.4), plantation around the house (aOR 43.8, 95% CI 1.9–1009.9), and raising animals (aOR 287.1, 95% CI 5.4–15205.6). CONCLUSIONS CL in Hajjah governorate was endemic and a wave of increase in cases was confirmed. Many individual, housing, and animal related factors had been shown to contribute to CL endemicity. Implementation of control measures directed towards altering the factors favoring contact between vectors, reservoirs, and susceptible humans are strongly recommended to control future outbreaks. Further studies focusing on species of parasite, vectors and reservoir are also recommended.

scholarly journals Risk factors for measles outbreak in Ataq and Habban districts, Shabwah governorate, Yemen, February to May 2018

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Abdulkareem Ali Hussein Nassar ◽  
Mohammed Abdullah Al Amad ◽  
Mohammed Qasim ◽  
Fekri Dureab
Keyword(s):  
Risk Factors ◽  
Vaccination Campaign ◽  
Immunization Coverage ◽  
Case Definition ◽  
Control Measures ◽  
Surveillance Program ◽  
Contributing Factors ◽  
Measles Outbreak ◽  
Surveillance And Response ◽  
Immunization Services

Abstract Background Recent conflict and war in Yemen lead to collapse of the health system, decrease of immunization coverage and spread of many outbreaks. On May 22, 2018, the surveillance officer in Shabwah governorate reported an increased number of suspected measles. On May 24, 2018, a team from Yemen-Field Epidemiology Training Program was sent to investigate. The aims were to describe the outbreak, determine the risk factors for measles infection and recommend control measures. Methodology A descriptive followed by case-control study design (1:2 ratio) were performed. National Measles Surveillance Program case definition and predesigned questionnaire were used to collect data from 73 cases and 146 controls. Attack rate (AR), adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) were calculated. P value < 0.05 was considered as the cut point for significant. Epi info version 7.2 was used. Results A total of 73 suspected cases were found. Almost 53% were from Habban district, 63% were males and 56% were among age group < 5 years. The overall AR was 82/100,000 population. Measles was significantly associated with contact with case (aOR = 27.3, 95% CI:1.3–551.7), malnourished children aged 6–60 months (aOR = 24.9, 95% CI;1.9–329.6) and unvaccinated children (aOR = 17.2, 95% CI:2.9–100.7). The six collected blood samples found to be positive for measles IgM. Conclusions Measles outbreak in Ataq and Habban districts was confirmed. Contact with measles cases, malnutrition and un-vaccination were the potential contributing factors of measles outbreak in Shabwah governorate. An urgent vaccination campaign with health education interventions are highly recommended. Reactivation of the outreach immunization services and strengthening surveillance and response systems are top priority to take place at district and governorate levels.

Epidemiology, risk factors and sequelae of venous thromboembolism

2012 ◽  
Vol 27 (2_suppl) ◽  
pp. 2-11 ◽  
Author(s):  
P Wong ◽  
T Baglin
Keyword(s):  
Risk Factors ◽  
Venous Thromboembolism ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Medical Practitioners ◽  
Vte Prophylaxis ◽  
Vein Thrombosis ◽  
Underlying Malignancy ◽  
Patients At Risk ◽  
Thromboembolic Pulmonary Hypertension ◽  
One Year

The aim of this review was to discuss the epidemiology, risk factors and sequelae of venous thromboembolism (VTE). VTE has an incidence of 1–2 per 1000 people annually. The risk of VTE increases with age and is highest in Caucasians and African Americans. Combined oral contraceptives (COC), especially the third-generation COCs, have been strongly implicated in VTE. Hospitalized patients, especially patients with underlying malignancy and undergoing surgery, have a host of risk factors for VTE. Thrombophilia can predispose an individual to VTE but indiscriminate testing for thrombophilia in patients presenting with VTE is not indicated. VTE can have serious chronic sequelae in the form of post-thrombotic syndrome (PTS) and chronic thromboembolic pulmonary hypertension (CTPH). The risk of PTS and CTPH is increased with recurrent deep vein thrombosis and pulmonary embolism, respectively. Mortality from VTE can be as high as 21.6% at one year. Patients who had an episode of VTE have a high risk of subsequent VTE and this risk is highest in patients who had a first VTE event associated with malignancy. A good understanding of the epidemiology and risk factors of VTE will enable the treating medical practitioners to identify patients at risk and administer appropriate VTE prophylaxis to prevent the longterm consequences of VTE.

scholarly journals Patients’ Educational Program Could Improve Azathioprine Adherence in Crohn’s Disease Maintenance Therapy

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Lei Wang ◽  
Rong Fan ◽  
Chen Zhang ◽  
Liwen Hong ◽  
Tianyu Zhang ◽  
...  
Keyword(s):  
Risk Factors ◽  
Crohn’S Disease ◽  
Crohn's Disease ◽  
Maintenance Therapy ◽  
Educational Program ◽  
Demographic Data ◽  
Univariate Analysis ◽  
Educational Group ◽  
One Year ◽  
Relapse Rates

Aim. To determine the risk factors of nonadherence to azathioprine (AZA) maintenance therapy for Crohn’s disease (CD) and to evaluate the influence of patients’ educational program on adherence to AZA maintenance therapy. Methods. Patients receiving AZA as maintenance therapy for CD were enrolled. Demographic data, clinical data, and usage information were collected. Univariate and multivariate analyses were performed to identify the risk factors of nonadherence. Then, patients’ educational program was conducted. One year after the program, the improvements in adherence and relapse rates were compared between educational and noneducational groups. Results. A total of 378 CD patients receiving AZA as maintenance therapy were enrolled from September 2008 to September 2018. Nonadherence occurred in 43.9% (166/378) of patients. Univariate analysis revealed that young age, education, alcoholism, anxiety, depression, concern belief, and lack of necessity belief and AZA knowledge were risk factors of nonadherence (P<0.05). Multivariate logistic regression showed that anxiety (OR 6.244, 95% CI 2.563–15.213), depression (OR 3.801, 95% CI 1.281–11.278), and concern belief (OR 19.531, 95% CI 3.393–120.732) were independent risk factors of nonadherence. Necessity belief (OR 0.961, 95% CI 0.925–0.999) and AZA knowledge (OR 0.823, 95% CI 0.758–0.903) were protective factors of adherence. One year after the AZA educational program, the necessity belief, AZA knowledge, and adherence of the educational group significantly improved (P<0.05). Concern belief was significantly lower in the educational group than that in the noneducational group (P<0.05). Moreover, the noneducational group suffered significantly higher endoscopic relapse rates than that the educational group (15.9% vs. 30.1%, P=0.035). Conclusions. Nonadherence occurred frequently in CD patients receiving AZA maintenance therapy. Educational programs could improve patients’ adherence mainly by promoting their beliefs and knowledge of AZA and could reduce relapse rates during treatment.

scholarly journals Frequency of infectious gastrointestinal illness in Australia, 2002: regional, seasonal and demographic variation

2005 ◽  
Vol 134 (1) ◽  
pp. 111-118 ◽  
Author(s):  
G. V. HALL ◽  
M. D. KIRK ◽  
R. ASHBOLT ◽  
R. STAFFORD ◽  
K. LALOR ◽  
...  
Keyword(s):  
Risk Factors ◽  
Socioeconomic Status ◽  
Telephone Survey ◽  
Case Definition ◽  
Infection Frequency ◽  
Multivariate Logistic Regression ◽  
Australian Population ◽  
Infectious Gastroenteritis ◽  
Potential Risk Factors ◽  
One Year

SUMMARYTo estimate the frequency of infectious gastroenteritis across Australia, and to identify risk factors, we conducted a national telephone survey of 6087 randomly selected respondents in 2001–2002. The case definition was three or more loose stools and/or two or more vomits in a 24-hour period in the last 4 weeks, with adjustment to exclude non-infectious causes and symptoms secondary to a respiratory infection. Frequency data were weighted to the Australian population. Multivariate logistic regression was used to assess potential risk factors including season, region, demographic and socioeconomic status. Among contacted individuals, 67% responded. The case definition applied to 7% of respondents (450/6087) which extrapolates to 17·2 million (95% CI 14·5–19·9 million) cases of gastroenteritis in Australia in one year, or 0·92 (95% CI 0·77–1·06) cases/person per year. In the multivariate model, the odds of having gastroenteritis were increased in summer and in the warmest state, in young children, females, those with higher socioeconomic status and those without health insurance.

scholarly journals Environmental Sanitation Factors and human Behaviour Associated with Intestinal Parasitic Infections in Rural Communities of Cameroon

2020 ◽  
pp. 1-12
Author(s):  
Natchema S. F. Brice ◽  
Atembeh Noura E. ◽  
Nkengazong Lucia ◽  
Ebogo Belobo Jean Thierry ◽  
Ngo Ngué Thérése Nadyne ◽  
...  
Keyword(s):  
Risk Factors ◽  
Univariate Analysis ◽  
Multivariate Logistic Regression Analysis ◽  
Control Measures ◽  
Multiple Infections ◽  
Parasitic Infections ◽  
Risk Area ◽  
Intestinal Parasitic Infections ◽  
High Risk Area ◽  
Human Aspects

Introduction: Intestinal parasitic infections still constitute major public health threats in many areas in Cameroon. To improve control measures, epidemiological data from environmental and human aspects are necessary to draw concrete control strategies to better follow-up the population at risk. Aim of the Study: This study aimed to investigate environmental risk factors related to infections in the Lolodorf health district, a high risk area of south Cameroon. Methods: A total of 325 participants who gave their informed consent were recruited for the study. Stool samples were collected and examined microscopically in search of helminth eggs and protozoan cysts using the Kato Katz and concentration Formol-ether techniques. Questionnaires were filled by participants to evaluate the risk factors. Results: Overall, 117 (42.9%) among the 325 participants harbored at least one parasite species with 75 (27.5%) having single infections and 42 (15.4%) having multiple infections. Ascaris lumbricoides (11.0%), Trichuris trichiura (26.4%), Hookworms (12.5%), Entamoeba coli (10.6%) and Entamoeba histolytica / Entamoeba dispar (1,5%) were diagnosed. Females were more infected (48.7%; p=0.04) compared to males (35.2%). Infection rate varied significantly according to villages (p=0.001). Univariate analysis revealed the following: gender (48.7%; p= 0.04), agricultural activities (47.7%; p= 0.04) and absence of treatment (50.8%: p=0.02) to be risk factors correlated to infection. Other factors such as age (49.3%), family size (47.8%), absence of toilets (53.5%), irregular use of shoes (48.6%), not wearing shoes (60.0%), irregular hand washing before meals (48.4%) and eating raw food (45.5%) had high infestation rates though with no significance. Multivariate logistic regression analysis showed that people who had never received any treatment had high risks of being infected (p=0.01; OR =0.17; 95% CI = 0.06 to 0.5). Conclusion: Improved sanitation, water supply and regular and extended deworming in the entire communities are fundamental issues in controlling intestinal parasitic infections.

scholarly journals An outbreak of Norovirus infections associated with recreational lake water in Western Finland, 2014

2018 ◽  
Vol 146 (5) ◽  
pp. 544-550 ◽  
Author(s):  
A. Polkowska ◽  
S. Räsänen ◽  
H. Al-Hello ◽  
M. Bojang ◽  
O. Lyytikäinen ◽  
...  
Keyword(s):  
Lake Water ◽  
Univariate Analysis ◽  
Multivariable Analysis ◽  
Case Definition ◽  
Control Measures ◽  
Evidence Based ◽  
Recreational Water ◽  
Fecal Indicator ◽  
Source Of Infection ◽  
Stool Samples

AbstractIn July 2014, an outbreak of gastroenteritis occurred among visitors to lakes in Tampere, Finland. We conducted a retrospective cohort study using an internet-based survey, solicited by public announcement, to identify source of infection and to implement control measures. Of 1453 persons enrolled in the study, 244 met the case definition (attack rate, 17%). In the pooled univariate analysis, risk factors for gastroenteritis included getting water in the mouth while swimming (Risk ratio (RR) 3.32; 95% Confidence interval (CI), 2.36–4.68) and playing on the wet sand at the beach (RR 1.90; 95% CI 1.50–2.41). In a multivariable analysis (logistic regression), the source of the infection was likely at two lakes (lake A Odds ratio (OR) 1.66; 95% CI 1.15–2.39 and lake B, OR 2.35; 95% CI 1.49–3.72). Norovirus (NoV) was found in 19 stool samples. All water samples from implicated beaches had acceptable values of fecal indicator bacteria and were negative for NoV. The likely source of the outbreak was lake-water contaminated with NoV at two popular lakes. Closure of swimming beaches, advice on hygienic precautions and rapid outbreak alerts were efficient in controlling the outbreak. Results suggest a need for new indicators of water quality and development of evidence-based recommendations regarding timing of safe reopen of recreational water venues associated with outbreaks.

scholarly journals 1513Foodborne Outbreak in the Central Prison, Amanat Al-Asimah, Yemen-October, 2020

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Salwa Al-eryani ◽  
Mohammed qeran ◽  
labibah Saeed ◽  
Yasser Ghaleb
Keyword(s):  
Risk Factors ◽  
Negative Impact ◽  
Poor Country ◽  
Case Definition ◽  
Foodborne Illness ◽  
Control Measures ◽  
Logistic Analysis ◽  
Important Health ◽  
Contaminated Food ◽  
Water Tanks

Abstract Background Foodborne diseases continuous to be one of important health problem in Yemen. On October 9, 2020, the surveillance officer in Amanat Al-Asimah reported increased number of diarrhea cases in the prison. On October 10, 2020, team from Y-FETP was sent to determine the magnitude of the outbreak, identify risk factors and recommend control measures. Methods Descriptive and case control study with a ratio of (1: 1) was conducted. Case defined as any person in prison developed of diarrhea or vomiting/nausea or abdominal cramps from 1st-15th October. Control defined as: any person in prison not developed of diarrhea or vomiting or any symptoms. Data was collected by using prepared line list and multivariable logistic analysis used for identifying risk factors. Results A total of fifty-one cases met the case definition. All cases were males with the mean of age (31.3±3.06). Al-Qala’ah ward was the most affected area (AR 5.7/100) and none of the cases died. The implicated food items were: tomato sauce (OR 4.92: CI 2.11-11.49) and potato sauce (OR 5.68: CI 2.29-14.07). Tanks were open and in bad condition and handling of food were poor. Laboratory results of examined food and water samples revealed Shigella flxneri sero type II and coliform growth and Staph. aurous were isolated from nasal of 3 cookers. Conclusions The foodborne outbreak in prison was associated with eating contaminated food in main restaurants. Monitoring of food consumed, rigorous implementation of food handling instructions and health education of handlers, and periodic inspection of water tanks in prisons are recommended. Key messages Highlight the importance of foodborne illness which leads to a negative impact on affected people loss of work, medical costs, long-term disability, and even death.in addition to bad impact on the economy especially in a poor country such as Yemen which has lacked awareness of the foodborne illness and doesn't have any surveillance system and regulation

scholarly journals Serum Epidemiological Analysis and Risk Factors Associated with Leptospira spp. in Cattle in the State of Piauí

2017 ◽  
Vol 45 (1) ◽  
pp. 11
Author(s):  
Siluana Benvindo Ferreira ◽  
Katiene Régia Silva Sousa ◽  
Vanessa Castro ◽  
Sabrina Thabla Pereira Lopes ◽  
Sávio Benvindo Ferreira ◽  
...  
Keyword(s):  
Risk Factors ◽  
Logistic Regression ◽  
Regression Analysis ◽  
Logistic Regression Analysis ◽  
Statistical Significance ◽  
Univariate Analysis ◽  
Multivariate Logistic Regression Analysis ◽  
Control Measures ◽  
Factors Associated ◽  
Leptospira Spp

Background: Leptospirosis is a cosmopolitan zoonosis caused by pathogenic spirochetes of the genus Leptospira spp. and it is considered one of the main causes of reproductive problems in cattle. Therefore, the aim of this study was to determine the occurrence of anti-Leptospira antibodies and identify the prevalent serovars and risk factors associated with infection in cattle herds, in the microregion of Floriano, Piaui State, Brazil.Materials, Methods & Results: A total of 414 bovine sera samples were collected (390 females aged over 24 months and 24 bulls) from 22 properties (farms) in the municipalities that compose the study area. The samples were analyzed using the Microscopic Agglutination Test (MAT) to detect anti-Leptospira antibodies from 23 pathogenic serovars. An epidemiological questionnaire was applied in each farm to evaluate the risk factors, using a univariate analysis of the variables of interest, by Pearson’s Chi-square test (χ2) or Fisher’s exact test, when it was necessary. Then, each independent variable was crossed with the dependent variable and those that presented statistical significance <0.20 were selected for multivariate analysis, using logistic regression, adopting a significance level of 5%. This research identified 143 positive animals (MAT> 1: 100) in the 22 evaluated farms; all of them had at least one positive animal, resulting in a prevalence of 34.54%, with 32,8% females (136) and 1,7% males (07), and 8,93% (37) of co-agglutination. Nineteen of the 23 tested serovars were identified; among them, Icterohaemorrhagiae (42.48%), Hardjo (31.2%), Pomona (4.3%), and Castellonis (4.3%) stood out. Absence of quarantine (OR = 16.172, P = 0.024), vaccination (OR = 0.090, P = 0.037) and isolation of diseased animals (OR = 0.006, P = 0.030) were identified, by the multivariate logistic regression analysis, as risk factors for any serovar of Leptospira spp.Discussion: The results of the present study showed that leptospirosis is present in all studied municipalities, in which the prevalence may be related to the variety of factors that influence the occurrence of the disease, such as climatic and environmental conditions, transit of animal, practices of management adopted in the herd, and the lack of information about the disease. The occurrence of co-agglutination can be explained by the possibility of multiple and concomitant contaminations with several serovars. Icterohaemorrhagiae was the most prevalent serovar, which has significant importance to public health since it is considered the main serovar of leptospirosis in humans, associated with the presence of rodents. On the other hand, the serovar Hardjo is related to the chronic leptospirosis in cattle, demonstrated through reproductive problems. The serovars Castellonis and Pomona were also observed in bovine herds, suggesting a possible transmission of the microorganism between animal species, probably due to exposure to the same sources of infection. In fact, the large number of serovarieties of Leptospira spp. indicates the presence of one or more maintenance hosts, which are natural reservoirs of this infection. The risk factors confirmed in the logistic regression analysis probably occur due to failures in sanitary management. It is concluded that Leptospira spp. is disseminated in cattle in the studied region, with the presence of several serovars, which reinforces the need for intensifying the prevention and control measures, such as vaccination.

6 COVID-19 outbreak investigation in a London army barracks. Understanding prevalence, seroconversion, transmission risk factors and control measures for COVID-19

2021 ◽  
Vol 167 (3) ◽  
pp. e1.6-e1
Author(s):  
Hannah Taylor ◽  
David Ross ◽  
William Wall
Keyword(s):  
Risk Factors ◽  
Infectious Virus ◽  
Respiratory Infections ◽  
Univariate Analysis ◽  
Female Gender ◽  
Control Measures ◽  
Transmission Risk ◽  
Rt Pcr ◽  
Neutralising Antibodies ◽  
Increased Risk

IntroductionMilitary Establishments are at increased risk of rapid spread of respiratory infections. Little was known in March 2020 about SARS-CoV-2 prevalence, serological conversion, asymptomatic transmission or risk factors for transmission, particularly in military populations. Early identification, swift implementation of control measures, and investigation of a potential outbreak with Public Health England in an Army barracks following one confirmed case and 11 symptomatic personnel, allowed exploration of these questions.MethodsAll adult personnel, including civilians working or living at the Barracks were invited to participate at initial visit and day-36 follow-up. Participants completed a symptom and transmission risk factor questionnaire; gave nasal and throat swabs for SARS-CoV-2 RT-PCR, infectious virus isolation, whole genome sequencing (WGS); and blood samples to detect SARS-CoV-2 and neutralising antibodies. Risk factors were statistically analysed using STATA v15.0, described in univariate analysis by relative risks and assessed using Fisher’s Exact test.ResultsAt first visit, 24/304 (8%) participants were RT-PCR positive and infectious virus recovered from 7/24 (29%). Seropositivity was 7% (19/285). 64% of all positive participants were asymptomatic. WGS identified more than three separate introductions, and evidence of asymptomatic transmission through genetically indistinguishable samples. Significant transmission risk factors included contact with a confirmed case, female gender, and two-person shared bathrooms. After 36 days, there were no new cases, all previously RT-PCR positive participants seroconverted, but not all developed neutralising antibodies; seropositivity was 13% (25/193).ConclusionsMost positive military personnel were asymptomatic, but those with symptoms reported ageusia or anosmia. Some RT-PCR positive participants, but none who were simultaneously positive for neutralising antibodies, had infectious virus. Initial infection rates were five times general London estimates, but effective implementation of control measures including enhanced cleaning, social distancing, and prompt isolation mitigated on-site spread. 36 days later seropositivity was below London’s rate. Ongoing risks include new COVID-19 introduction into the barracks from off-site personnel, asymptomatic transmission between cases and contacts, and use of two-person bathrooms.

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