Foodborne Outbreak investigation: Al-Ahsa, Saudi Arabia, 2021. A retrospective cohort study (Preprint)

BACKGROUND On 10 September 2021, Al-Ahsa General Health Directorate reported unexpected number of patients had presented with gastrointestinal symptoms. All the patients gave a history of sharing a common meal as they ate from dinner was served at the mother's house the day before. OBJECTIVE We investigated to verify the outbreak, determine its magnitude, identify the source and implement control measures. METHODS A retrospective cohort design was conducted. Cases were defined as any person who ate dinner at the family gathering on the 9th of September 2021 and developed any or a combination of the following symptoms: diarrhea, vomiting, fever, or abdominal pain within 26 hours of food consumption. We collected information on demographics, symptoms, and food history using a semi-structured questionnaire. We reviewed hospital records for symptoms and Vital sings. We reviewed available laboratory results for cases, we conducted active case search to identify more cases. statistical analyses were performed using SPSS 21.0. RESULTS Twenty subjects were defined as cases (74%) and seven as non-cases (26%). among cases, 16 were females (80%), and 4 were males (20%). The ages ranged between 2–70 years. Among cases (59.3%) had vomiting, (59.3%) had a fever, (48.1%) developed diarrhea, (25%) abdominal pain. The incubation period ranged from 10-26 hours (mean 17.8). The relative risks and p- value were calculated for food items to assess the association between consumption of individual food items and subsequent illness. Among 8 food items consumed, red pasta with chicken (Relative Risk RR= 3.14, 95% CI = 3.2-424.6) and pizza (RR= 1.73, 95% CI = 1.74-42.2) were significantly associated with illness. CONCLUSIONS According to the epidemiological investigation, symptoms, incubation period, and laboratory results there might be some differential diagnosis, but we were unable to more definitively identify the source of the outbreak. We recommend more education to the households about food safety

Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F4:Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior

We present a systematic study on the properties of Na(Y,Gd)F4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10–50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes.

The Effect of Information-Driven Resource Allocation on the Propagation of Epidemic with Incubation Period

In the pandemic of COVID-19, there are exposed individuals who are infected but lack distinct clinical symptoms. In addition, the diffusion of related information drives aware individuals to spontaneously seek resources for protection. The special spreading characteristic and coevolution of different processes may induce unexpected spreading phenomena. Thus we construct a three-layered network framework to explore how information-driven resource allocation affects SEIS (Susceptible-Exposed-Infected-Susceptible) epidemic spreading. The analyses utilizing microscopic Markov chain approach reveal that the epidemic threshold depends on the topology structure of epidemic network, and the processes of information diffusion and resource allocation. Conducting extensive Monte Carlo simulations, we find some crucial phenomena in the coevolution of information diffusion, resource allocation and epidemic spreading. Firstly, when E-state (exposed state, without symptoms) individuals are infectious, long incubation period results in more E-state individuals than I-state (infected state, with obvious symptoms) individuals. Besides, when E-state individuals have strong or weak infectious capacity, increasing incubation period have an opposite effect on epidemic propagation. Secondly, the short incubation period induces the first-order phase transition. But enhancing the efficacy of resources would convert the phase transition to a second-order type. Finally, comparing the coevolution in networks with different topologies, we find setting the epidemic layer as scale-free network can inhibit the spreading of the epidemic.

Transmission and containment of the SARS-CoV-2 Delta variant of concern in Guangzhou, China: A population-based study

Background The first community transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant of concern (VOC) in Guangzhou, China occurred between May and June 2021. Herein, we describe the epidemiological characteristics of this outbreak and evaluate the implemented containment measures against this outbreak. Methodology/Principal findings Guangzhou Center for Disease Control and Prevention provided the data on SARS-CoV-2 infections reported between 21 May and 24 June 2021. We estimated the incubation period distribution by fitting a gamma distribution to the data, while the serial interval distribution was estimated by fitting a normal distribution. The instantaneous effective reproductive number (Rt) was estimated to reflect the transmissibility of SARS-CoV-2. Clinical severity was compared for cases with different vaccination statuses using an ordinal regression model after controlling for age. Of the reported local cases, 7/153 (4.6%) were asymptomatic. The median incubation period was 6.02 (95% confidence interval [CI]: 5.42–6.71) days and the means of serial intervals decreased from 5.19 (95% CI: 4.29–6.11) to 3.78 (95% CI: 2.74–4.81) days. The incubation period increased with age (P<0.001). A hierarchical prevention and control strategy against COVID-19 was implemented in Guangzhou, with Rt decreasing from 6.83 (95% credible interval [CrI]: 3.98–10.44) for the 7-day time window ending on 27 May 2021 to below 1 for the time window ending on 8 June and thereafter. Individuals with partial or full vaccination schedules with BBIBP-CorV or CoronaVac accounted for 15.3% of the COVID-19 cases. Clinical symptoms were milder in partially or fully vaccinated cases than in unvaccinated cases (odds ratio [OR] = 0.26 [95% CI: 0.07–0.94]). Conclusions/Significance The hierarchical prevention and control strategy against COVID-19 in Guangzhou was timely and effective. Authorised inactivated vaccines are likely to contribute to reducing the probability of developing severe disease. Our findings have important implications for the containment of COVID-19.

Bio-priming of Aceh local chili seeds in the effort to increase production and begomo virus resistance

The purpose of this study was to determine whether P60 could induce resistance in local Aceh chili varieties to begomovirus and compared with national varieties. This research was conducted at the Experimental Farm, Genetics and Plant Breeding Laboratory, Faculty of Agriculture, Syiah Kuala University, Banda Aceh, from March to July 2021. This study used a factorial randomized block design. The tested factors consisted of two factors. The first factor is bio priming. The second factor consists of four local Aceh chili varieties, namely: V1 = Odeng, V2 = Lanyoe, V3 = Super Lamando and V4 = LamandoLapaben and one national variety, namely V5 = Baja F1 as a comparison variety. The results showed that the best local Aceh variety was LamandoLapaben for the variables of resistance response, incubation period, disease intensity, disease incidence, stem diameter, and crown width. The best local variety Aceh Lanyoe on plant height and dichotomous height parameters. Giving P60 can reduce the percentage of disease incidence by 52.00% and slow down the process of emergence of disease symptoms (incubation period) 27.11 DAP. The best combination treatment was the LamandoLapaben variety, which was 1.41 milligram Units-1 (Umg)-1.

Isolation Of Pseudomonas Aeruginosa from Soil and Production of Lipase Enzyme

The isolates of Pseudomonas aeruginosa bacteria were uncovered in the soil surrounding the roots of palms and public gardens in Baghdad for the production of lipase enzyme. The lipase enzyme has many applications that are included in the textile and food industry, and the manufacture of detergents and medical preparations. Several tests such as temperature change, incubation period, change of lipid sources, nitrogen sources such as peptone and tryptone, and carbon sources such as glucose and lactose were carried out to choose suitable conditions for bacterial growth. The results indicated studying the conditions affecting production, it was noted that the best production was when using the culture medium to which 1% of corn oil was added, pH 7, at a temperature of 37 °C and an incubation period of 24 hours in vibrating incubator at 151 rpm, The soil surrounding the roots of the plant is a good reservoir for the presence of Pseudomonas aeruginosa bacteria

Business Incubation Initiatives Impact on Entrepreneurs and SMEs

Business incubation (BI) is a strategic tool that helps a country to grow its entrepreneurial base and reduce the high mortality rate of SMEs. Kingdom of Eswatini adopted the business incubation initiatives to promote entrepreneurship and SME development. To date, no data exist on the impact made by business incubation initiatives. Adopting methodological triangulation of both quantitative and qualitative data collected through questionnaires and interviews where the participants consisted of SME owners, BI managers, and BI trainers, this exploratory study aims to investigate business incubation initiatives' impact on entrepreneurs and SMEs. Findings reflect that BIs measure their impact by seeing an increase in revenue, increase in the number of people employed, and SME survival post the incubation period. Though SMEs agreed that the BI effects positively, the study also revealed that some SMEs remained in the incubation for more than 10 years. Policy implications emerging are the need to introduce graduation policy and proper determination of requirements for incubation.

COVID-19: Salient Aspects of Coronavirus Infection, Vaccines and Vaccination Testing and their Implications

In the present study, three basic aspects related to COVID-19 are presented. (a) The occurrence of coronavirus infection is analyzed statistically as number of coronaviruses infected alveolar cells compared to normal alveolar cells in human lungs. The mole concept is used to estimate the number of normal alveolar cells per human lung. The number of coronavirus infections in infected alveolar cells is estimated from the published Lower Respiratory Tract (LRT) load data. The Poisson probability distribution is aptly applied to imply the incubation period of the coronavirus infection to be within day-3 to day-7, with the cumulative probability of 75%. The incubation period within day-0 to day-10 has a cumulative probability of 98%. It implies a 10-day quarantine to isolate an uninfected individual as a precautionary measure. (b) Three vaccines to combat COVID-19, which adopt distinct paradigms while preparing them, are analyzed. These are Moderna's mRNA-1273, Oxford-AstraZeneca's ChAdOx1 nCoV-19 and Bharat BioTech's COVAXIN. The mole concept is used to estimate the antigen mass density per dose of each of these vaccines as 10, 0.1 and 1 (g per cubic-cm), respectively. The vaccines are deemed to be compatible to neutralize the infection. (c) A statistical analysis is performed of the Moderna's mRNA-1273 vaccine efficacy of 94.1% and Oxford's ChAdOx1 nCoV-19 vaccine efficacy of 62.1% in terms of groups of volunteers testing negative to vaccine by chance. In the Moderna vaccination testing scenario, since the probability of negative response of vaccine is small, the Poisson probability distribution for 95% cumulative probability is used to describe the vaccination testing in 300 samples of 47 volunteers each. Thus, 87% of samples have average group of 3 volunteers testing negative to vaccine. About 6% of samples have all volunteers testing positive to vaccine. In the Oxford vaccination testing scenario, since the probability of negative response of vaccine is finite, the Gaussian probability distribution for 95% probability is used to describe the vaccination testing in 75 samples of 120 volunteers each. Thus, 68% of samples have average group of 45 volunteers testing negative to vaccine. No sample has all volunteers testing positive to vaccine. A vaccine, irrespective of its efficacy being high or low, is necessary for mass immunization.

Meta-analysis of the severe acute respiratory syndrome coronavirus 2 serial intervals and the impact of parameter uncertainty on the coronavirus disease 2019 reproduction number

The serial interval of an infectious disease, commonly interpreted as the time between the onset of symptoms in sequentially infected individuals within a chain of transmission, is a key epidemiological quantity involved in estimating the reproduction number. The serial interval is closely related to other key quantities, including the incubation period, the generation interval (the time between sequential infections), and time delays between infection and the observations associated with monitoring an outbreak such as confirmed cases, hospital admissions, and deaths. Estimates of these quantities are often based on small data sets from early contact tracing and are subject to considerable uncertainty, which is especially true for early coronavirus disease 2019 data. In this paper, we estimate these key quantities in the context of coronavirus disease 2019 for the UK, including a meta-analysis of early estimates of the serial interval. We estimate distributions for the serial interval with a mean of 5.9 (95% CI 5.2; 6.7) and SD 4.1 (95% CI 3.8; 4.7) days (empirical distribution), the generation interval with a mean of 4.9 (95% CI 4.2; 5.5) and SD 2.0 (95% CI 0.5; 3.2) days (fitted gamma distribution), and the incubation period with a mean 5.2 (95% CI 4.9; 5.5) and SD 5.5 (95% CI 5.1; 5.9) days (fitted log-normal distribution). We quantify the impact of the uncertainty surrounding the serial interval, generation interval, incubation period, and time delays, on the subsequent estimation of the reproduction number, when pragmatic and more formal approaches are taken. These estimates place empirical bounds on the estimates of most relevant model parameters and are expected to contribute to modeling coronavirus disease 2019 transmission.