Epidemiological studies have a broad range of purposes, but their main focus is to determine the prevalence or incidence of various diseases or infectious outbreaks. This study wanted to determine if E. coli O157:H7 infection was a disease outbreak or an isolated case. Specifically, in the middle of the spring of 2018, there was a sharp increase in hospitalizations due to fever, bloody diarrhea, and dehydration. The decision to conduct the study was made when a number of people with more than four events of bloody diarrhea per day started to be brought to the hospital in Littletown. For this incident to be considered an outbreak, there should be a doubling of the cases compared to the usual amount. The study’s results indicate the outbreak since the numbers within one year increased 2-3 times. It appears that the population at risk are children of age 0-10 as well as young and middle-aged individuals in the 20-40 age range. This report aims to summarize the recent E. coli outbreak in Littletown and provide recommendations for future studies.
Study Analysis
The retrospective data in this study was obtained from interviewing patients who had the abovementioned symptoms from April 18, 2017, to March 18, 2018. Notably, only patients with the confirmed presence of the pathogen in their stool samples were included in this research. The risk measures used in this case were mortality and morbidity rates. The latter is defined as “the portion of people in a specific geographical location who contracted a particular disease during a specific period of time” (CFI, 2020, para. 1). It indicates how frequently people living in a certain area get a particular disease (CFI, 2020). The morbidity rate is calculated by estimating the ratio of people who had the disorder to the whole population. Since the total number of infected patients in the town is 100, the morbidity rate is approximately 0. 0005 in individual hospitals in 2018: MR = (7+5+3+15+12+10)/205,692 = 0.0005. In 2017, this number was equal to 0.00025, twice as low as the next year, indicating it was an outbreak in 2018.
Specific patterns can be noticed when the risks are calculated for various age ranges and city areas. For example, the most significant threat to contracting the infection was in the area of Northern Lights hospital because it reported the highest number of cases and hence the largest morbidity rate: 60/205,692=0.0003. On the other hand, the Whispering Pines hospital had morbidity of only 2/205,692=0.00001. When age ranges are considered, the highest rate was in those 30-40 years old in 2017 and 2018 (Table 1). Although the lowest risk seemed to be among individuals older than 80, it might be due to the overall low number of people of advanced age in Littletown. Notably, the outbreak appeared to target children below age ten and adults aged 20-40.
Table 1: Morbidity rate from the infection in 2017 and 2018
Recommendations
It is strongly recommended to take immediate measures to prevent future outbreaks. E. coli O157:H7 is a dangerous strain since it can cause hemolytic uremic syndrome, which, as the name suggests results in red blood cell destruction and kidney failure (Weerarathne et al., 2021). The main problem of this pathogen, like many other successful microbes, is the ability to form biofilms. It is a dense colony of bacteria in a packed matrix of extracellular polymeric substances that protect microorganisms from the effect of antibiotics and other measures people take for sanitation (Weerarathne et al., 2021). Humanity has long been struggling with biofilms since some solutions and detergents seem to be ineffective against them. Still, researchers identified some that can destroy biofilm formations; for example, sodium acid sulfate was shown to eliminate almost entirely E. coli O157:H7 biofilms in vitro (Weerarathne et al., 2021). Therefore, the proposed recommendation is to adopt this or other equally efficient solution in restaurants, kitchens, public transport, and workplaces for cleaning the surfaces to prevent future outbreaks.
Suggested Follow-Up Study
In this case, the follow-up study should be performed on the patients’ health status since the pathogen has long-term adverse sequelae for the human organism. Several types of research are used in epidemiology for such purposes, including case-control, cohort, and cross-sectional studies (Belbasis and Bellou, 2018). Firstly, case-control studies the outcomes in the cases and comparison groups based on their exposure status (Belbasis and Bellou, 2018). Secondly, cross-sectional studies examine exposure and consequence at one time period (Belbasis and Bellou, 2018). Thirdly, cohort studies allow for retrospective and prospective assessment of people being exposed to specific factors that contribute to a particular outcome (Belbasis and Bellou, 2018). For Littletown’s outbreak, the most suitable follow-up would be a retrospective cohort study, allowing researchers to find associations between one or several exposures and the infection. The goal of this study will be to identify what factor played the most significant role in this infectious outbreak. Specifically, it will be crucial to determine what aspects had the strongest association with E. coli O157:H7 infection in this town.
The data will be collected from people who were affected by this outbreak using questionnaires. Furthermore, the comparison group will be people who did not have the symptoms of food poisoning during that period. To have a larger sample size, contact details of patients will be requested from all hospitals in the town where these individuals were admitted with the symptoms of diarrhea, fever, and dehydration. They will first be contacted through a call to ask if they are interested in participating in this study, and then they will be sent an online questionnaire. People for the control group will be recruited through social media advertisements. Table 2 shows what questions the future survey will approximately have.
Table 2. Questionnaire for the follow-up study
Conclusion
In summary, this report assessed the data obtained from the 2018 E. coli O157:H7 outbreak and provided recommendations for a follow-up study. Indeed, as the comparison between the number of infectious cases in 2017 and 2018 showed, there was a doubling or tripling of affected people; hence, it can be considered an outbreak. Finally, the follow-up cohort study will strive to determine the association between the exposure and the outcome.
Reference List
Belbasis, L. and Bellou, V. (2018) ‘Introduction to epidemiological studies’, in Evangelou, E. (ed.) Genetic epidemiology: methods and protocols. New York, NY: Springer New York, pp. 1-6.
CFI (2020) Morbidity rate.
Weerarathne, P., et al. (2021) Evaluating the efficacy of sodium acid sulfate to reduce Escherichia coli O157:H7 and its biofilms on food-contact surfaces. LWt, 139, pp. 1-7.