Risk factors for Streptococcus pyogenes skin infections during an outbreak in Ethiopia: a case-control study.

Background: Despite being in existence for hundreds of years, Streptococcus pyogenes remains a significant cause of global morbidity and mortality, with a particular impact in resource-limited settings like Ethiopia. Even though research on Streptococcus pyogenes skin infections in Ethiopia is growing, there's a gap in identifying the potential risk factors contributing to this infection with prevention and control measures. The primary objective of this case-control study design was to identify potential risk factors of Streptococcus pyogenes skin infections and outbreak investigation was also undertaken to control and prevent the spread of Streptococcus pyogenes.

Methods: A case-control study was conducted in the South Gondar Zone of Andabet and Dera districts from December 10, 2022, to January 10, 2023. An active case search was done with house-to-house by using epidemiologically linked case definitions, and a total of 914 residents were attacked by the outbreak. A face-to-face interview using a structured questionnaire was carried out to collect data. Epi Data version 4.6 and STATA version 17 software were used for data entry and analysis, respectively. Regression analysis was computed, and variables with a P-value of ≤ 0.05 were considered as statistically significant risk factors.

Result: Group A beta-hemolytic streptococcus pyogenes was identified during the outbreak investigation. The attack rate of the infection was 22.2 cases per 1,000 population. The logistic regression analysis revealed that contact with cases (OR = 5.98, 95% CI: 2.91-12.25), poor personal hygiene (OR = 0.37, 95% CI: 0.2-0.66), inadequate water access for hygiene (OR = 2.2, 95% CI: 1.27-3.76), inadequate clothing practices (OR = 0.41, 95% CI: 0.23-0.70), and presence of injury (OR = 9.8, 95% CI: 5.85-18.41) were statistically significant risk factors.

Conclusions and recommendations: Significant risk factors included contact with cases, poor personal hygiene, inadequate water access for hygiene and clothing practice, and injury. Improving personal hygiene, increasing water access, and injury prevention are recommended to reduce S. pyogenes transmission. S. pyogenes infection should be included in the national public health surveillance system. Longitudinal studies should be conducted to track the impacts of S. pyogenes infections over time in the same population.