Salmonella serotypeTyphi , Shigella , and intestinal parasites among food handlers at Bahir Dar University , Ethiopia

Introduction:Food handlers play a major role in the transmission of Salmonella serotype Typhi (S. Typhi), Shigella, and intestinal parasites. This study was conducted to determine the prevalence of S. Typhi, Shigella, and intestinal parasites among food handlers at Bahir Dar University, Ethiopia. Methodology: A cross-sectional study was conducted in June 2014. Stool samples from 410 food handlers were examined for bacterial pathogens and parasites. Pearson’s Chi-square test, Fisher’s exact test, and bivariate and multivariate logistic regression analyses were used where appropriate. Results: The prevalence of S. Typhi, Shigella, and intestinal parasites among food handlers was 11 (2.7%), 5 (1.2%), and 53 (12.9%), respectively. Among eight intestinal parasites identified, the two most prevalent intestinal parasites were hookworm 26 (6.3%) and G. lamblia 13 (3.1%). Male food handlers were more likely to be positive than were female food handlers for S. Typhi and intestinal parasites. Furthermore, food handlers who had a history of regular medical checkups were less infected with intestinal parasites. Being male (AOR: 2.1, 95% CI: 1.2, 4.4) and not attending medical checkups (AOR: 2.9, 95% CI: 1.4, 6.1) were independent predictors of intestinal parasitic infection in food handlers. Male food handlers were reluctant to have regular parasitological examinations. Conclusions: There was a high proportion of food handlers with S. Typhi, Shigella, and intestinal parasites in their faces. Special emphasis should be placed on S. Typhicarriers and male food handlers. Education and periodical medical checkups for intestinal parasites and S. Typhi should be considered as intervention measures.


Introduction
Foodborne diseases are a major public health problem worldwide.According to the World Health Organization (WHO)'s estimates, 30% of the population suffers from foodborne diseases in developing countries, and two million deaths occur each year [1].The problem is more severe in developing countries because of a lack of resources for environmental sanitation and personal hygienic practices [2].In developing countries, 70% of cases of diarrhea are associated with the consumption of contaminated food [3].Food handlers with poor personalhygiene working in food-serving establishments could be potential sources of foodborne infections [2,4].
Among sub-Saharan African countries, Ethiopia has the second-and the third-highest burden of Ascaris lumbricoides and hookworm, respectively [5,6].
Studies in different parts of Ethiopia reported that 29%-49.4% of food handlers working in various food establishments had intestinal parasites [4,[7][8][9].Therefore, food handlers can transmit intestinal parasites that do not require environmental maturation [10].
Salmonella serotype Typhi (S.Typhi) and Shigella are major causes of foodborne infections.Thus, they remain as important public health problems worldwide [11].Moreover, clinical management and control of typhoid fever is challenging, especially in Africa, because of the development of multidrug resistance and vaccines are not immunogenic to young children [12].Shigella spp.are more endemic in temperate and tropical climates.Globally, Shigella spp.cause approximately 80-165 million cases of morbidity and 600,000 deaths annually [13].Therefore, food handlers who have S. Typhi and Shigella may contaminate foods during processing.
Although various studies have been conducted to assess the prevalence of intestinal parasites among food handlers in different parts of Ethiopia, there is limited data on the prevailing prevalence of intestinal parasites, S. Typhi, and Shigella among food handlers in the study area.This study was therefore conducted to determine the prevalence and predictors of S. Typhi, Shigella,and intestinal parasites among food handlers working in mass catering establishments in Bahir Dar University, Ethiopia.

Study design
A cross-sectional study was conducted among foodhandlers working in catering establishments in Bahir Dar University in June 2014.During the study period, food handlers who had been on antibiotics and/or antiintestinal parasites within the last 10 weeks were excluded.

Sample size and sampling technique
Sample size was determined using a single population proportion formula, considering 95% confidence interval (CI), 50% intestinal parasite prevalence, and margin of error of 5%.Moreover, 10% for no response rate was applied; thus, the final sample size was 422.The participants were selected randomly using registration lists.

Data collection
A pretested questionnaire was used to collect information by face-to-face interview.Information such as age, sex, service year, educational level, hand washing practices, and practice of medical checkups were collected from each study participant.

Parasitic examination
Food handlers were provided with clean, screwcapped containers after orientation.Stool specimens were collected at the microbiology laboratory, and samples were soon examined for intestinal parasites.Detection and identification of intestinal parasites were performed using saline direct wet mount at the parasitology laboratory by experienced parasitologists.

S. Typhi and Shigella isolation
Stool specimens were enriched in selenite F broth for 18 hours and inoculated into xylose-lysinedeoxycholate agar (XLD) (Oxoid, Basingstoke, UK) and MacConkey agar (BD, Difco, USA) and incubated for 24 hours at 37°C. S. Typhi and Shigella spp.were identified using biochemical tests used according to the Clinical and Laboratory Standards Institute [14].

Statistical analysis
The data were entered and analyzed using the Statistical Package for Social Sciences (SPSS) version 20 software.Pearson's Chi-square test and Fisher's exact test, where appropriate, were used to associate the prevalence of S. Typhi, Shigella,and intestinal parasites with categorical variables.Bivariate and multivariate logistic regression analyses were computed.Variables having a p value less than 0.2 in the bivariate analysis were considered for multivariate logistic regression analysis.

Ethical considerations
Prior to data collection, ethical approval was secured from the Research and Ethics Review Board of Bahir Dar University.Informed written consent was also obtained from each study participant.The study participants found to be positive for intestinal helminths and S. Typhi and Shigella were treated accordingly by physicians.

Results
A total of 410 food handlers (326 females and 84 males) participated in the study.The median age of the participants was 24 years.The majority of food handlers (81.3%) had one to five years of work experience.The educational levels and age categories of the participants are depicted in Table 1.
In hand washing assessment, 98.7% females and 94% males had a habit of washing their hands after using the toilet (Table 1).There was significant difference between genders in the practice of hair covering during food preparation (P= 0.01).Among participating food handlers, 78.3% of females and 15.6% of males had a habit of covering their hair during food processing (Table 1).Only 40 (9.7%) of food handlers were certified in safe food preparation and handling practices.At the time of survey, 52.2% food handlers had in-service training for safe food preparation and handling practices.

S. Typhi and Shigella
Overall, 16 (3.9%) of food handlers had either S. Typhi or Shigella spp.The prevalence of S. Typhi and Shigella spp., were 11 (2.7%) and 5 (1.2%), respectively (Table 1).A statistically significant difference was noted between female and male food handlers for S. Typhi because more male food handlers 123 were carriers of S. Typhi (P = 0.004).However, there was no significant difference for Shigella species (P = 0.272) (Table 2).

Intestinal parasites
The overall prevalence of intestinal parasites was 53 (12.9%).Of these, 37 (11.3%)female and 16 (19.0%)male food handlers had intestinal parasites.A statistically significant association was observed between gender and prevalence of intestinal helminths (P = 0.01) (Table 3).Furthermore, food handlers who had regular medical checkups were less infected with intestinal parasites than those who did not (P = 0.001) (Table 4).The predominant intestinal parasites identified in food handlers were hookworm and G. lamblia.Multivariate logistic regression analysis predicted that male food handlers were twice more likely to have intestinal parasites (adjusted odds ratio [AOR]: 2.1; 95% CI: 1.2, 4.4) than females.Moreover, individuals with no practice of regular medical checkup were 2.9 times more likely to be infected with intestinal parasites than were their counterparts (Table 4).

Discussion
The present study showed that 12.9%, 2.7%, and 1.5% of food handlers were carriers of intestinal parasites, S. Typhi, and Shigella spp., respectively.Thus, food handlers harboring intestinal parasites that do not need environmental maturation such as G. lamblia and S. Typhi may contaminate food and spread the parasites directly to clients in food establishments [10].
In this study, single stool samples were used from each study participant rather than the triplicate samples recommended to detect intestinal parasites.Furthermore, direct saline was used to examine stool samples.Therefore, the prevalence of intestinal parasites may have been underestimated.The prevalence of intestinal parasites among food handlers in the present study conforms to the prevalence of intestinal parasites reported from India [15] and Thailand [16].However, it is lower than findings reported in other part of Ethiopia.For instance, prevalences of intestinal parasites were reported to be 49.4% from Mekelle [9], 41.1% from Bahir Dar [4], and 44.1% from southwest Ethiopia [8].However, the prevalence of helminths in the present study (9.5%) was higher than the 3.0% prevalence reported from Mekelle, Ethiopia [9].The differences might be attributed to differences in geographical variation and sociodemographic characteristics of the study population.Hookworm was the most prevalent parasite followed by G. lamblia among food handlers.Likewise, a study in Thailand reported that hookworm is the most prevalent infection among food handlers, with prevalence of 7.69% [16].Furthermore, prevalances of hookworm of 8.1% and 8.3% were documented in Ethiopia [4] and Qatar [17], respectively.The prevalence of G. lamblia in the present study (3.1%) was lower compared to other findings in different part of Ethiopia, which reported 5.9% to 7.9% prevalence [4,8].Food handlers with G. lamblia infection may directly transmit the parasite to consumers if it is ingested via contaminated food and water because G.lamblia cysts do not need environmental maturation AOR: adjusted odds ratio; CI: confidence interval [10].Moreover, Mintz et al. found that food handlers infected with G. lamblia were a vehicle for a G. lamblia outbreak in a commercial food establishment [18].An interesting observation in the present study was that the prevalence of intestinal parasites was significantly higher in male food handlers than in female food handlers (P= 0.001).Although further study is required to elucidate the factors, poor practice of seeking medical checkups such as parasitological examination in male food handlers might be a factor.Likewise, higher prevalence of intestinal parasites in male than in female food handlers was reported from a study conducted in Thailand [16].In the present study, 3.9% of food handlers either S. Typhi or Shigella spp., indicating that food handlers in mass catering establishments are potential sources of typhoid fever and shigellosis infection in the student population.The prevalence of S. Typhi in the present study (2.7%) was higher than that reported from Gondar (1.3%) and Bahir Dar (1.6%), Ethiopia [4,19].However, high prevalence of S. Typhi in food handlers was reported from Sudan (3.8%) [20] and India (17.14%) [21].These findings indicate that food handlers who carry S. Typhi might play a role in the foodborne spread of S. Typhi.In this study, the prevalence of Shigella spp.among food handlers (1.5%) conforms to reports from Jordan (1.4%)and Sudan (1.3%) [20,22].It is known that Shigellaand S. Typhido not have any natural reservoirs except humans; therefore, primary modes of transmission are associated with poor sanitation and hygiene practices of food handlers.Therefore, food handlers who carry Salmonellaand Shigella should not be allowed to work until they are treated and completely cured.

Conclusions
This study revealed that food handlers working in a students' catering establishment had a high prevalence of S. Typhi, Shigella, and intestinal parasites.The prevalence of S. Typhiand intestinal parasites were significantly higher in male food handlers then in female food handlers.Lack of medical checkups was associated with the prevalence of S. Typhi and intestinal parasites.Thus, annual medical checkups of food handlers for both intestinal parasites and S. Typhishould be encouraged and enforced.Furthermore, health education on safe food handling and personal hygiene are important intervention measures.

Table 1 .
Demographic and hygienic practice of food handlers in Bahir Dar University, 2014

Table 4 .
Multivariate logistic regression analysis of predictors of intestinal parasitic infection among food handlers