Surveillance data has shown an increase in Salmonellosis cases in Riyadh city during the last two years. During this period there were four outbreaks in the area (Abha, Riyadh and Muscat) related to eggs. We began to investigate this problem to estimate the risk of Salmonella from eggs in Riyadh city.
Methodology
A matched case-control study was carried out. All the cases and controls were asked about the foods eaten during the last three days to identify the food items responsible for these sporadic cases. We then calculated the odds ratio for each food item and for egg handling procedures. We asked the families to explain the preparation of the desserts and mayonnaise.
Results
We were able to investigate 60 of the 113 Salmonellosis case patients who visited the five hospitals during the period from May 3 to July 4, 1998. All the cases developed diarrhea. There was a significant association between eating egg dishes and developing illness for all Salmonella cases (OR= 2.7 and 95% CI= 1.5-4.9) and for Salmonella serotype group D cases (OR=4.5 and 95% CI= 2.1-9.7). Also, there was a significant association between both the storage of eggs, the method of buying eggs, and the possibility of the eggs being dangerous. Additionally, there was a significant association between the location where eggs were cooked and the use of unsafe eggs.
Conclusion
Eggs are an important source of Salmonellosis in Riyadh city. Raw eggs and light cooking contribute to human infection. Poor temperature control in storing eggs (in both markets and homes) also contributes to infection.