This study employed a case-control design with 60 cases and 120 controls in Shagar City, Oromia region, Ethiopia, with the goal of describing the affected population descriptively and identifying risk factors for cholera outbreak in three sub-cities (Burayu, Lega Tafo& Lega Dadi, and Koye fache) based on cases load. According to the descriptive study, the age group of 18 to 34 years old accounted for the largest proportion of all cases 24, or 40% of the affected population, with a median age of 31 years. The percentage of males was significantly higher, at 60%, and the overall attack rate was 0.12 per 1000 people. Several factors were linked to cholera cases in bivariable and multivariable analysis, including living in a single household, eating out, drinking contaminated water, and consuming raw vegetables and unsafe drinking water, people live in one household, and sharing latrines with other households, which were statistically associated with the outbreak. Hands washing with soap after using the latrine, and having a latrine household level have all been found to be protective factors against cholera, demonstrating the importance of hygiene in cholera prevention. Cholera has been termed as the disease of poverty since social risk factors play a great role in the transmission and can affect people of all ages. Our finding showed that the most affected age group was 18–34 years old. A similar study finding was detected in Ethiopia and Uganda Bumbuli Distract ,which indicated the most affected age group was 20–29 years old (9, 22). Our finding contradicts the study conducted in Nigeria to analyze the factors contributing to cholera where the aged 44–56 group was more affected, and Uganda ,where the more affected age group was 2–5 years (20, 23), The reason could be due to the frequent movement of these age groups for different activities from one village to the others. One of the outbreak disease impacts and its burden measurement on the population affected is the attack rate. The impact of the outbreak increases with its attack and fatality rate. According to this study, the district's cholera attack rate was 0.12 per 1000 population. This finding has a low attack rate in comparison to cholera outbreak findings in other countries (8, 9). This can be due to the multi-faceted role involving the timely implementation of public health measures, the implementation of community inconveniences, and environmental remediation. The outbreak investigation's Epi-curve revealed that many peaks showed progressive person-to-person transmission of cholera due to poor sanitation and personal hygiene. This finding is similar to one found in a study conducted in Kirkos, Addis Ababa (24). This can be attributed to secondary cases with varying incubation times caused by contact infection from person to person or via an intermediate host or carrier until control measures are implemented. Disease outbreaks, particularly cholera outbreaks, are frequently linked to poor water and sanitation conditions around the world (22). Cholera is a disease of poverty that lacks social development in the areas where the disease occurs. Inadequate access to clean water, poor environmental and health care, and sanitation services, and low-income countries with poor hygiene standards, increase the likelihood of cholera outbreaks (25). According to our findings, cholera outbreaks occurred in the sheger city as a result of drinking unsafe water and inadequate sanitation services, and a lack of adequate clean water. This finding is similar and comparable with finding conducted in Addis Ababa, Ethiopia, Yemen, and India revealed that contaminated drinking water is the primary driving force of cholera outbreaks (24, 26, 27). Moreover, a study conducted in Ethiopia and Iran revealed that poor sanitation and a lack of water are risk factors for cholera outbreaks (25, 28). A cholera outbreak in the sub-city has been linked to poor sanitation and a lack of access to safe drinking water, as well as drinking untreated water. Fresh vegetables usually contain non-pathogenic epiphytic microorganisms that occur naturally; however, pathogens from animal and human sources can contaminate the products during growth, harvest, transportation, and subsequent handling (3). Vibrio cholera can contaminate raw vegetables at any point in the production chain, from the grower to the consumer's mouth, and vibrio cholera can survive for 2 to 5 days on contaminated products (29). In our study, we found that eating raw vegetables like tomatoes without washing was an independent risk factor for the cholera outbreak. This finding is consistent with previous research findings conducted in Bangladesh, which stated that the primary route of cholera pathogen transmission was eating raw vegetables without washing(30). It is critical to wash vegetables and fruits before eating them. Cholera spreads through feces, contaminated food, carriers, and unsanitary environmental conditions. Food can be contaminated by asymptomatic infected people during preparation, but it can also be contaminated by utensils, with Cholera remaining on utensils for 1 to 2 days (31).
Cholera is mostly an easily transmittable disease from person to person contact with the infected case or by contaminated materials (10). Several existing studies have found that a history of contact with infected patients increases the risk of cholera disease transmission from an infected person to another through contact by 4 to 5 times, and the risk is even higher among household contacts (30, 32). Our findings also revealed that exposure to cholera cases in the sub-city was statistically significant to the disease and was a risk factor. Similar study findings conducted in Bangladesh, individuals in household contacts were found to be 5 times more likely than non-contacts (30) .Taking precautions when in contact with cases can help to reduce the risk of transmission. Hand washing with soap is essential for preventing the spread of V.cholerae during food preparation, serving, and consumption, as well as when visiting latrines. Chlorination and boiling drinking water is safe and protects against cholera infection (18, 33). Our investigation found that treating drinking water and washing hands regularly with soap after visiting the latrines were independent protective factors against cholera infection. The findings of a similar study were supported by the findings of an investigation into a cholera outbreak in other settings. Kirkos Addis Ababa, India and Yemen (18, 24, 27, 34). This is that demonstrated, cholera transmission can be stopped by implementing food and personal hygiene measures. Having and using improved sanitary facilities that are not shared with other households, as well as not flushing or pouring-flushing latrines connected to a sewer system and a septic tank, is an effective method of preventing and controlling cholera transmission (8, 35). According to our recent finding, cholera infection was less likely to affect households with latrines in the study area. This finding is consistent with those of a study conducted in Kenya's Dadaab refugee camp ,Uganda, and Ethiopia (18, 36, 37).This suggests that a household with its latrine is less likely to be infected than a household with a shared latrine.
Public health interventions
The main purpose of outbreak investigation is to provide efficient and effective public health interventions timely to stop the spread of disease to other areas and decrease cases and deaths.
Accordingly major public health intervention undertaken at this sub-city were establishment of cholera task force comprising of different government sectors, active case search and health education at house hold level, orientation of health professionals working in CTC, distribution of water treatment chemical by ORHB and UNICEF and monitoring and evaluation activities.
In collaboration with the Oromia Regional Health Bureau, UNICEF, Shaggar city, and the 12 sub city Health Office: CTU and CTC has been established in 12 sub city, and active monitoring of acute watery diarrhea has been improved. During the first few weeks of the outbreak, health promotion and hygiene campaigns were carried out, primarily through community mobilization. In schools, marketplaces, and religious centers, extensive health education on hygiene promoters and the use of water treatment chemicals, the benefit of hand washing with soap and using latrine has been conducted. To implement the interventions, the Shaggar city and 12 Sub city used a multi-sectorial approach that included disease surveillance, patient care, infection control, health education and promotion, construction and use of latrines, promoting hand washing, and enforcing sanitation and hygiene through strategies such as sanitation campaigns to improve sanitation, as well as rebuilding and maintaining water sources. Borehole water was chlorinated, soap was distributed, and latrines were disinfected in affected households. WASH partners were advised to maintain adequate chlorine levels, install more taps and latrines (particularly in unofficial settlement areas), and increase hand washing facilities in food and drink establishment, and health facility.
Limitations of the study
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The main limitation of this study it was conducted only at a three sub-city, because of in rest sub city which has low load cases and limitation of resources.
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Control stools were not tested due to a lack of test kit.