The main risk factors for Salmonella infection in the Caribbean outbreak are eating raw or undercooked eggs (Stehr-Green, 2004). Other studies identify that direct contact with domestic animals, particularly poultry, is also a risk factor (Djeffal et al., 2018; Dang-Xuan et al., 2019). The main factor contributing to infection is the close proximity of domestic birds to the place of food production. Additional risk factors are poor hygiene and the consumption of contaminated water (Stehr-Green, 2004; Djeffal et al., 2018; Dang-Xuan et al., 2019). A key aspect of outbreak prevention is maintaining hygiene in pet and poultry farms and ensuring access to clean water. Insufficient sanitation of domestic animals and poultry houses is a major risk factor for the development of Salmonella and its transmission to humans through eggs and meat.
Salmonella is usually transmitted to humans through the consumption of contaminated food, particularly eggs and meat from poultry and domestic animals. Additionally, Salmonella can be transmitted to humans through direct contact with pets (Djeffal et al., 2018). Another important route of transmission is through drinking contaminated water (Stehr-Green, 2004; Dang-Xuan et al., 2019). It is also important that insufficient hygiene of food workers (insufficient handwashing) can cause infection transmission.
To calculate the incidence rate, it is necessary to divide the number of cases by the population at risk. Therefore, it is additionally necessary to find the size of the population that inhabited Trinidad and Tobago in each of the years. Between 1988 and 1997, the population of Trinidad and Tobago was about 1.200.000 people (1.204.000-1.259.000) (Trinidad and Tobago population, n.d). To calculate the incidence rate, it is necessary to divide the number of new cases by the population size. To find the average value for the period, you need to find the average value of the number of new cases over ten years. For the period from 1988 to 1997 in Trinidad and Tobago, the average Salmonella incidence rate was 9.08 per 100.000. The annual prevalence rate per 100,000 people is presented in Table 1; the average prevalence rate for the period from 1988 to 1997 is 0,0092%.
Tab. 1. The prevalence of Salmonella in Trinidad and Tobago population from 1988-1997.
The case study report identifies that an average of 4 people per year died from Salmonella infection (Stehr-Green, 2004). To find the mortality rate, it is necessary to divide the number of deaths by the population at risk. Thus, it is necessary to divide 4 by 1.200.000, which equals 0.000003. Therefore, the annual mortality rate from Salmonella infection in Trinidad and Tobago was 0.0003%.
The case study also presents odds ratios that allow associations to be made between a potential source of infection and the disease. Thus, the strongest correlation exists between infection and eating food with raw or undercooked eggs. This means that this method of infection is the most common. Eating shell eggs is also a common potential method of infection, but the odds ratio for it is almost twice lower. Odds ratios for ground beef, powdered milk, and live chickens exposure range from 1.3 to 1.5, which identifies a low risk of infection from them. Finally, storage and consumption of eggs from the refrigerator have the lowest odds ratios. Thus, the most common potential sources of infection are the consumption of raw and undercooked eggs, as well as the consumption of shell eggs.
References
Dang-Xuan, S., Nguyen-Viet, H., Pham-Duc, P., Ungerm F., Tran-Thi, N., Grace, D., & Makita, K. (2019). Risk factors associated with Salmonella spp. prevalence along smallholder pig value chains in Vietnam.International Journal of Food Microbiology, 290, 105-115. Web.
Djeffal, S., Mamache, B., Elgroud, R., Hireche, S., & Bouaziz, O. (2018). Prevalence and risk factors for Salmonella spp. contamination in broiler chicken farms and slaughterhouses in the northeast of Algeria.Veterinary World, 11(8), 1102-1108. Web.
Stehr-Green, J. K. (2004). Salmonella in the Caribbean.
Trinidad and Tobago population.(n.d). Worldometer. Web.