Showing 17 results for Outbreak
B Eshrati, A Rezaei Ashtiani , F Khazaei, F Torkamani, M Azimi,
Volume 3, Issue 1 (9-2007)
Abstract
Background & Objectives: The summer of 2005 witnessed an outbreak of cholera in Iran due to V. cholera, Inaba serotype. During the outbreak, there were 16 registered cases in Markazi Province. The aim of this study was to determine the risk factors for cholera outbreak in this part of the country.
Methods: This was a case-control study in which cases were matched to controls on age and sex. All of the reported cases were compared with controls from the same neighborhood, with 2 controls selected for each case. We used paired odds ratios and conditional logistic regression to show the effect of each putative risk factor, and p values of < 0.05 were considered as statistically significant.
Results: Multivariate results from 16 cases and 32 controls showed significant associations between the cholera outbreak and the following set of factors: eating raw vegetable (OR=9, 95%CI: 2.25-35.98), proper warming of refrigerated food (OR=0.12, 95%CI: 0.015-1.022), inadequate washing of fruits and vegetables (OR=4.29, 95% CI: 0.88-21.06) , and eating non-pasteurized ice creams (OR=4.96, 95%CI: 0.99-24.83).
Conclusions: Although the number of reported cases was small in Markazi Province, the results show that education in personal hygiene is important in the prevention of a cholera outbreak.
Ha Barati, A Golmohmmadi, I Momeni, G Mpradi,
Volume 6, Issue 3 (12-2010)
Abstract
Background & objectives: However outbreaks of cholera are not very common in central area of Iran, in 2008 district health authority reported a cluster of diarrhea cases. We investigated this cluster to identify the etiological agent, source of transmission and propose control measures.
Methods: We defined a case of diarrhea as occurrence of > or =3 loose/watery stools a day among the residents of Karaj. Fifty four (54) cases were identified in health care centers and 106 healthy individuals as control. We conducted a gender- and age-matched case-control study to identify risk factors.
Results: Vibrio cholerae El Tor O1 Inaba was isolated from all cases rectal swabs. during cholera epidemic outbreak in 2007, 54 cases of stool-culture were vibrio cholera, serotype Inaba positive. Using industrial-ice and fruits and vegetables were significantly associated with the illness (OR 4.4 and 3.3 respectively).
Conclusions: This outbreak was due to a contaminated industrial-ice and contaminated vegetables and fruits and V. cholera 01 Inaba was possibly the causative organism. Therefore more prevention program and observation methods should be considered.
M Karami, H Soori, Y Mehrabi, Aa Haghdoost, Mm Gouya,
Volume 8, Issue 3 (12-2012)
Abstract
Background & Objectives: Knowledge of the presence of seasonal trends and other explainable patterns in the prediagnostic data sources and removing such patterns before applying outbreak detection methods seem very important. This study aimed to detect and remove the explainable patterns such as seasonality, day-of-week (DOW) and holiday effects of the daily counts of suspected cases of measles in Iran.Methods: Data on daily counts of suspected cases of measles as a pre-diagnostic data source were obtained from Iranian national surveillance system between 21 March 2008 and 20 March 2011. We used lines plot, moving average chart, autocorrelation and partial autocorrelation functions for detecting explainable patterns. Moving average (MA) and Holt- Winters (HW) exponential smoothing method are used for removing explainable patterns.
Results: Our findings indicate the presence of seasonality, DOW effect, holidays and weekend effects in the daily counts of suspected cases of measles. The good performance of HW exponential smoothing technique in removing seasonal patterns is evident. MA technique showed better performance regarding assumption violation on outbreak detection methods.
Conclusion: Because of the presence of explainable patterns in the daily counts of suspected cases of measles, considering such patterns before applying outbreak detection algorithms is very important. Implementing both MA (7 days) techniques for its simplicity as a pre- processing method and HW method for its efficacy in removing seasonal patterns is recommended.
M Karami, H Soori, Y Mehrabi, Aa Haghdoost, Mm Gouya,
Volume 8, Issue 3 (12-2012)
Abstract
Background & Objectives: Evaluating the performance of outbreak detection methods using real data testing provide the highest degree of validity. The aim of this study was to determine the performance of the Exponentially Weighted Moving Average (EWMA) in real time detection of two local outbreaks in Iran.
Methods: The EWMA algorithm (both ƛ= 0.3 and 0.6) applied on daily counts of suspected cases of measles to detect local outbreaks which had been occurred in Mashhad and Bandar Abbas cities during 2010. The performance of The EWMA algorithms were evaluated using real data testing approach and reported by correlation analysis.
Results: Mashhad outbreak was detected with a delay of about 2 to 7 days using EWMA algorithms as outbreak detection method while the utility of EWMA algorithms in real time detection of Bandar Abbas’ outbreak were on time good optimal. Maximum correlation value for EWMA 2 in relation to Mashhad outbreak was 0.60 at lag 2.
Conclusion: Applying the EWMA algorithm as an outbreak detection method at local levels is not suggested. However the characteristics of data are determinant of the performance of such detection methods.
M Karami, H Soori, Y Mehrabi, Aa Haghdoost, Mm Gouya, N Esmailnasab,
Volume 9, Issue 2 (10-2013)
Abstract
Background & Objectives: Timely response to emerging diseases and outbreaks are a major public health and health systems priority. There are few published studies that evaluate the performance of cumulative sum (CUSUM) on identical data using semi- synthetic simulation approach. This study was undertaken to determine the performance of the CUSUM in timely detection of 831 days of simulated outbreaks.
Methods: We evaluated the performances of the CUSUM as an outbreak detection method on simulated outbreaks injected to daily counts of suspected cases of measles as baseline data in Iran between 21 March 2008 till 20 March 2011. Data obtained from the Iranian national surveillance system. The performance of algorithms was evaluated using sensitivity, false alarm rate, likelihood ratios and Area under the Receiver Operating Characteristic (ROC) curve.
Results: Generally the sensitivity of the CUSUM algorithm in detecting simulated outbreaks was 50%
(95% CI: 47- 54). The corresponding values are disaggregated according to outbreak size, shape and duration. The CUSUM algorithm detected the half of outbreaks after 13.84 days on average.
Conclusion: We concluded that CUSUM algorithm performed good in detection of large outbreaks with short periods and poorly in detecting long period outbreaks, particularly those simulated outbreaks that did not begin with a surge of cases.
H Hatami, B Kalantari, Ar Farsar, A Asgari, S Karkhaneh,
Volume 11, Issue 4 (3-2016)
Abstract
Background and Objectives: Acute gastroenteritis is mainly caused by some viruses and often NoVs. In January 2014, an outbreak of gastroenteritis occurred in Pardis City, in Tehran and that made 5064 patients visit health centers. The purpose of this study was to investigate the epidemiology of the disease in this region.
Methods: This cross sectional study was done to evaluate the outbreak of gastroenteritis in Pardis City in January 2014. In this outbreak, the data of 1150 out of 5064 patient was collected by health centers. The inclusion criterion was residing in the location for at least ten days before its occurrence. The exclusion criterion was incomplete recorded data. A number of 126 human samples underwent laboratory investigation. The data collection tool was was line listings and data analysis was done with Excel 2010 and SPSS21 software.
Results: female and male patients comprised 57.8 and 42.2% of the study population and 59.7% of the subjects were under 27 years of age. The most prominent symptoms were vomiting (94.9%), diarrhea (37.7%), abdominal pain (18.8%), and fever (0.6%). The results showed that bacterial contamination, parasites, serologic tests for hepatitis E (IgM-HEV) and hepatitis A (IgM-HAV) and RT-PCR for hepatitis E and A were negative but 6 out of 9 fecal samples were positive for NoVs using molecular RT-PCR.
Conclusion: The results revealed the role of NoVs in Pardis City in 2014. Moreover, clinical and epidemiological characteristics of the population, season, and the environment of this diagnosis were confirmed.
K Jafari, M Karami, A Soltanian, N Esmailnasab,
Volume 12, Issue 2 (8-2016)
Abstract
Background and Objectives: Syndromic surveillance systems are used to early detection of outbreaks. The purpose of this study was to determine the feasibility of clinical and non-clinical data sources used in influenza syndromic surveillance in Zanjan.
Methods: In this time series study, clinical and non-clinical data related to influenza like illness (ILI) as a potential data source of syndromic surveillance systems, including the number of missed school days collected from 12 schools and the data of over the counter (OTC) drug sale obtained from 15 pharmacies selected randomly in Zanjan during 2014 were used. We used the line plot and moving average chart to explore trends and detect potential explainable patterns of data sources. The autocorrelation function and cross correlation function besides corresponding graphs were used to assess the feasibility of school absenteeism and OTC sale in timely detection of influenza outbreaks.
Results: Line plots indicated the presence of explainable patterns and the effect of the day of the week. The cross correlation value was 0.5 and cross correlogram revealed the similarity of both data sources in this study.
Conclusion: Our findings indicated the feasibility of influenza data sources, including school absenteeism and OTC, as potential data sources of syndromic surveillance systems.
S Holakouie Naieni , Sh Holakouie Naieni , K Holakouie Naieni ,
Volume 13, Issue 4 (3-2018)
Abstract
Background and Objectives: Food-borne diseases are serious problems in public health. Since the outbreaks can be prevented, we need to take action in the prevention of such infection. On 28 June, 2014 cases of gastroenteritis occurred in students living in dormitories of a medical university; therefore, this study aimed to investigate the outbreak of gastroenteritis to determine its risk factors.
Methods: This case - control study was performed to evaluate students. A total of 70 patients with gastroenteritis in the outbreak of 16 June 2014 were selected. A total of 70 students without any gastrointestinal complaints in the weeks before the outbreak were also selected as the control group using convenient sampling.
Results: The results of this study provided 4 main themes (challenges of access to the data of the surveillance system, challenges of access to the data of national surveys and ordered projects, challenges of access to the data of electronic health records, and challenges of access to confidential data) and 15 sub-themes.
Conclusion: According to the results, having lunch prepared by the university on 16 June was the likely cause of the outbreak on 17 June in student living in dormitories. Hygiene in cooking and food storage, especially in public places such as schools and universities are important in the prevention of food-borne outbreaks.
M Karami Jooshin , H Izanloo, A Saghafipour, F Rezaei, M Asadi Ghalhari ,
Volume 14, Issue 4 (3-2019)
Abstract
Background and Objectives: Cholera is one of the communicable diseases that should be reported immediately as a public health threat. This study was conducted to study the probable risk factors of cholera outbreak in Qom, central Iran, during 2017.
Methods: In a case-control study, 37 cholera patients diagnosed based on para - clinical tests and 37 control samples were evaluated. Charts, frequency tables, regression logistic, Chi-square and t-test in SPSS software ver.25 were used for data analysis.
Results: The causative agent in the Qom cholera outbreak was Vibrio cholerae serotype Inaba. Most of the patients (54%) were in the age range 21-40 years. Most of the cholera cases were males (87%), Iranians (81%), and school or college students (30%). The peak of the epidemic occurred in the third week of November 2017, coinciding with a religious event. Nearly half of the patients were identified at the cross-border surveillance centers. The most important risk factors for the outbreak were a history of travel to Iraq in order to attend the Arbaeen religious event (95%), (OR=75, P-value<0.001), and a history of consuming unreliable foods and water (94% and 50%, (OR=66, CI=8-410, P-value=0.00 and OR=11, CI=2.7-46)), respectively.
Conclusion: Cross-border surveillance of cholera in common borders with Iraq, especially in the Arbaeen religious event, played a vital role in identifying patients suspected of cholera. The surveillance of communicable diseases should be strengthened when entering and leaving the Arbaeen event.
M Karami, A Doosty Irani, Sj Battaei, L Rafati, M Javaheri, M Kheir Andish , M Farhadi, M Hashemi, K Mozafari, A Akhlagh, M Shojaeian, Ar Maleki, R Rostam Abadi , Sh Torkshavand, M Khodabakhshi,
Volume 16, Issue 3 (11-2020)
Abstract
Background and Objectives: Water and foodborne diseases are major causes of mortality worldwide. The aim of this study was to investigate the factors affecting an gastroenteritis outbreak in Hamadan county in summer of 2019.
Methods: This study was performed based on the outbreak investigation process. After producing hypotheses based on preliminary field studies, a case-control study was conducted on 45 cases and 45 controls to investigate the factors associated with the outbreak. New cases of the disease were included according to the case definition. A logistic regression model was used to investigate potential risk factors.
Results: A total of 171 people were affected in this outbreak from 25 June 2019 to 01 July 2019. The at-risk population in this outbreak was 3410 individuals. The attack rate was 5.1%. Abdominal pain, vomiting, and nausea were the most common symptoms with a prevalence of 77.8%, 73.3% and 68.9%, respectively. The results of the case-control study showed that the consumption of tap and spring/well water increased the odds of disease by 4.63 and 4.13 times compared to boiled water, although these relationships were not statistically significant. The odds of diseases were significantly lower in people aged 30-45 years and 46-85 years compared people aged 15 years old and younger.
Conclusion: Based on the results of this study, the outbreak was related to contaminated water consumption. Therefore, regular monitoring of drinking water status is very important for the local health system.
K Sharifolkashani, P Yavari, , R Shekarriz, F Tajdini, N Aghili,
Volume 16, Issue 4 (3-2021)
Abstract
Background and Objectives: Correct and timely detection of the outbreaks of diseases with a short incubation period is of great importance in the health system. The aim of this study was to determine the detection of dysentery outbreaks using the cumulative sum method.
Methods: This time series study was conducted using the data of the National Surveillance System between 2014 and 2017. The outbreak alert threshold of each season and province was determined separately using the average of three years (1393 to 1395) in the same season and province. The dysentery outbreak in each season was exclusively predicted for Isfahan, Khuzestan, and Hamadan provinces in 2017 using the CUSUM method.
Results: In Isfahan Province, the outbreak alert was higher in the spring and summer and lower in the autumn and winter using the current method compared to the CUSUM method. For Khuzestan Province, the current outbreak alert was significantly higher in all seasons compared to the CUSUM method, while the current outbreak alert was lower than the alert predicted by the CUSUM method in Hamadan Province in all the seasons.
Conclusion: Compared to constant threshold-based methods, using the CUSUM method seems to be a better way for reporting outbreaks, especially in areas with a high incidence.
H Amiri, Sh Salmanzadeh, F Safdari, A Shirali, E Azhdarinia, Kh Sarmadi, Sa Alavi, H Salehi, M Eskandari,
Volume 16, Issue 4 (3-2021)
Abstract
Background and Objectives: In June 2018 , 537 residents of a rural area in Khuzestan Province presented to the regional Comprehensive Health Service Center for gastroenteritis symptoms. This study was designed to determine the extent and cause of the outbreak.
Methods: A case-control study was performed after random selection of the case and control groups (80 cases and 88 controls). Clinical and water samples were analyzed for parasitic, bacterial and viral pathogens in local, provincial and national laboratories. Odds ratios with corresponding 95% confidence intervals were used to assess the relationship between disease and exposure.
Results: The odds ratio of rural plumbing water consumption as a risk factor was 3.3 (95% CI: 1.7-6.2). Using in vitro methods, Shigella sonnei was isolated in clinical samples and enterohemorrhagic Escherichia coli and enteropathogenic Escherichia coli were isolated from both clinical samples and water samples taken from the intake basin of water supply facilities.
Conclusion: Consumption of rural plumbing water Since 26 June 2018 as well as the water stored in domestic tanks at certain water-shut-off times is associated with gastroenteritis outbreak. To prevent similar outbreaks, continuous chlorination of drinking water during distribution through rural pipelines should be done. To prevent secondary outbreaks after the epidemic phase, educating and informing people about personal hygiene is essential.
Mohammad Ali Derik, Mohammad Kakavand, Shahram Mamdohi, Mojgan Navabi, Elham Goodarzi, Hamid Mokhayeri, Zaher Khazaei,
Volume 17, Issue 2 (9-2021)
Abstract
Background and Objectives: Viral hepatitis is one of the most prevalent diseases and an important underlying cause of death and disability in the world. This case-control study was conducted to investigate the outbreak of hepatitis A in Boroujerd in 2019.
Methods: This case-control study was conducted to investigate the epidemic of hepatitis A in Boroujerd in 2019. Fifty hepatitis A patients were recruited. For each patient diagnosed, two controls with no history of the disease were selected from a neighboring village. Data were collected using a demographic questionnaire as well as the results of experiments. To investigate the association between the disease and risk factors, odds ratio and 95% confidence interval were used.
Results: In this study, the odds ratios were significant for a number of risk factors including washing fruits and vegetables with a source other than tap water [OR = 3.2], washing dishes with a source other than tap water [OR = 3.7], non-sanitary toilets [OR = 8.3], using sources other than tap water when there is no tap water [OR = 4.4], being unaware of the disease and its transmission methods [OR = 4.8] and water well dug less than 15 m from the sewage well (OR = 4.1).
Conclusion: Increased public awareness and improved health status of the environment and rural sewage can preclude similar epidemics in the study area and other regions.
S Heidari, M Karami, Sm Zahraei, I Sedighi, F Azimian Zavareh,
Volume 17, Issue 3 (12-2021)
Abstract
Background and Objectives: Given the importance of the early detection of any outbreak or change in the trend of meningitis, this study was conducted to estimate the fixed and dynamic alarm threshold levels of meningitis and its outbreak in Iran.
Materials and Methods: In this study, the data of all patients from 20¬ March 2016 to 20 March 2019 were extracted from the National Meningitis Disease Surveillance System. Alarm threshold levels were calculated separately for different seasons and provinces. To determine the alarm threshold levels, four methods of Upper Control Limit (UCL), relative increase, statistical cut off points, and recommendations provided by the World Health Organization were used.
Results: The alarm threshold levels for confirmed cases were determined for Iran according to the upper limits of cumulative sum (CUSUM) algorithm and the statistical cut off points based on the 90th percentile, 2 cases per day for Iran. The fixed amount was 3 to 5 cases per week in populations under 30,000 and 5 to 7 per week in populations between 30,000 and 100,000. According to the relative increase method, a 30% increase in one week compared to previous weeks was considered as the threshold level.
Conclusion: The use of alarm threshold levels reported in this study can be a basis for detecting meningitis outbreaks.
T Arian-Mehr, M Karami,
Volume 17, Issue 4 (3-2022)
Abstract
Background and Objectives: Timely dection of influenza outbreaks is very important for a better reponse to outbreaks. The aim of this study was to assess the moving epidemic method for determinating influenza outbreak threshold levels in Iran.
Methods: The moving epidemic method was applied to the WHO Flunet website data from January 2010 to December 2017 with the aim of determining outbreak alert thresholds. Therefore, the performance of the moving epidemic method in identifying the onset of the outbreak over eight periods was reported using sensitivity and specificity indices.
Results: A total of 69169 influenza-like illnesses were recorded in the Fluent website during the study period. The smallest number of influenza-like illnesses for the epidemic was 187 cases in the third period (2011-2012) and the maximum number was 1086 cases in the seventh period (2016-2015). The earliest epidemic occurred during the third and eighth periods of the 48th week, approximately in mid-February. The minimum duration of the epidemic was 8 weeks and the maximum was 13 weeks. The overall sensitivity and specificity of the moving epidemic method were 55% and 96%, respectively.
Conclusion: The moving epidemic method could be used as a complementary method to detection of influenza outbreks. It is recommended to apply the moving epidemic method on influenza and similar communicable diseses.
P Maroofi, , Z Cheraghi, L Tapak,
Volume 17, Issue 4 (3-2022)
Abstract
Introduction: Identifying the epidemiological features of reported measles outbreaks including the size, period, and generation of the outbreaks plays a significant role in preventing new outbreaks and estimating effective reproduction number (R) as an indication of measles elimination. This study was conducted to describe the reported measles outbreaks in the world in 2018.
Method: The PubMed, Scopus, and Web of Sciences databases were searched using related keywords to retrieve articles that reported 2018 measles outbreaks. From the full-texts of the articles that met the inclusion criteria, the data including gender, season, age group, country, genotype, and vaccination status as well as shape, size, period of outbreaks and number of generations of each outbreak were extracted and reported using the relevant epidemiological curves.
Results: The search results led to the retrieval of 2806 articles. After screening, 16 studies were used for final analysis. Most outbreaks were reported in the winter (56.25%) with genotypes B3 and D8. The sex female (38.64%, 308 cases) was mostly in Asia and Europe. On average, the minimum and maximum number of outbreaks size was 1 and 23, which spread to 3-4 generations. In terms of death, only one case of death was reported in Ethiopia.
Conclusion: The results of this study are useful for identifying measles outbreaks in other countries according to the at-risk groups. However, publication bias and non-reporting of all outbreaks should be considered as limitations in the generalization of the results.
Elham Rahimi, Ebrahim Ghaderi, Ehsan Mostafavi, Mohammad Hossein Panahi, Manoochehr Karami,
Volume 19, Issue 1 (6-2023)
Abstract
Background and Objectives: The publication of outbreak investigation reports is critical for disseminating lessons learned from outbreaks. While there are existing reporting guidelines for outbreak investigations, there is a gap in specific guidelines for reporting food-borne and water-borne outbreaks. This study aims to introduce a specific framework and reporting guideline for food and waterborne outbreak investigations in Iran.
Methods: The initial draft of the framework for reporting food and waterborne outbreaks was derived from existing general reporting guidelines for outbreak investigations. Additionally, a systematic review of studies reporting outbreaks of waterborne and foodborne diseases from 2010 to 2022 was conducted without language restrictions to extract relevant information. Expert opinions were then sought to finalize and adapt the reporting guideline.
Results: The reporting guideline framework for outbreaks of waterborne and foodborne diseases consists of eight parts: title, abstract (background, methods, results, conclusion), introduction, methods (study characteristics, study type, variables under investigation), results (participant information, statistical results, laboratory results, environmental investigation results), discussion, conclusion, and conflict of interest.
Conclusion: This specific reporting guideline for food and waterborne outbreak investigations can be utilized by outbreak investigation teams, rapid response teams, and researchers to effectively report the results of outbreak investigations in this domain.
