Contamination of Ethiopian paper currency notes from various food handlers with E. coli

Currency notes are used for exchange of commodity and goods, including food. While so, it could be contaminated and represents as a vehicle for the transmission of pathogenic microorganisms in the environment and among humans (Michaels 2002; Xu et al. 2005). The Ethiopian currency called “Birr” is the second most used currency in Africa after Nigerian “Naira” for goods and services, including food and others, exchange in Ethiopia as in most other countries worldwide (Girma et al. 2014; Saripalli et al. 2014). The currency notes can be contaminated while counting using saliva, coughing and sneezing on hands followed by exchanging currency, placement or storage on dirty surfaces, poor hand washing post toilet. Such currency notes further act as a vehicle for bacteria to the next user (Barolia et al. 2011; Ngwai et al. 2011). Simultaneous handling of food and such contaminated currency could resulted in foodborne infection (Girma et al. 2014; Ngwai et al. 2011). Microbial contamination rate of currency handled by butchers (78.0 %) and food sellers (62.1 %) was also reported from Nepal (Lamichane et al. 2009). Microbial load of Bacilli, Coccus, Fungal species (Saripalli et al. 2014) from Axum-Ethiopia, Staphylococcus, Enterobacteriaceae, Micrococcus species, Streptococcus species (Girma et al. 2014) from Jimma-Ethiopia were reported from Ethiopian Birr. The Food and Agricultural Organization (2011) listed the possible means of food contamination and/or cross-contamination during growth and harvest (horticulture products), collection (milk) or slaughter (meat). Further contamination can occur during post-harvest handling, transport, processing and unhygienic food handling during preparation (FAO 2011). Escherichia coli (E. coli) was reported from currency at 5.6 % from Ghanaian Currency Notes (Tagoe et al. 2009). However, E. coli carriage of Ethiopian currency notes handled by various types of food handlers was not yet assessed and the isolates were not also tested for drug susceptibility in and around Haramaya district. Thus, the aim of this study was to assess contamination rate of Ethiopian polymer currency notes handled by various types of food handlers with E. coli in and around Haramaya district with antimicrobial susceptibility test on the selected isolates.

The present of E. coli on ETB at high level (75 %), and handled by five food classes (meat handler, open market milk seller, dairy station milk seller, bread and related food handlers, and fruit and vegetable sellers) at different locations indicates the likelihood of public infection with harmful microbial including pathogenic E. coli strain in the studied area. It was higher than the 50 % reported from Nigeria by Ngwai et al. (2011) in currency from samples including non-food items. This could be due to either contamination of the currency from food that had already contaminated with feces or others sources of E. coli. The moisture, sweat, air and others factors from the food at ambient temperature are driving force for contamination and survival of E. coli on the currency with risk of further contamination of food at any point. Lamichane et al. (2009) and Saripalli et al. (2014) also provided similar suggestion. Jay et al. (2005) also indicated the possible risk of food cross contamination at any point. Moreover, the present finding was quite higher than the 1.3 % E. coli species reported from the Polish Notes and Coins (Kalita et al. 2013 ) indicating the difference in hygienic handling condition between African and European country. Although the magnitudes were differ, microbial contamination of currency were reported globally (Kalita et al. 2013; Awel et al. 2010; Barolia et al. 2011; Girma et al. 2014). The absence of E. coli in new currency used for control but its presence on those circulating once indicates, the currency under usage harboring E. coli and other microbial. Similarly, Kalita et al. (2013) also indicated presence of opportunistic microbial on the used Polish Notes and Coins but not on the new ones. About greater than 70 % of ETB were harboring E. coli and showed high and equal contamination within and among studies variables (location, food types, sources, ages and sex of handlers) of the currency in the studied district. However, the low E. coli rate on currency from open market (47.1 %) than from dairy station (87.2 %) at milk sellers (handlers) from Haramaya University and the surrounding indicated high prevalence of E. coli in dairy farm that can act as source of currency contamination through the milk. In Ethiopia, poor-currency-handling culture is widespread, and there is indiscriminate abuse of currency notes reported by Girma et al. (2014). Observation of E. coli on currency handled by vegetable handlers in the present study could also be contamination of the specific food from already contaminated dust, soil and water as well as from microflora of the body of handlers. Awel et al. (2010) and Barolia et al. (2011) also provided the same suggestion by tracing contaminant E. coli to dust, soil, water and the microflora of the body of handlers (hand, skin and others). Moreover, paper currency can acquire E. coli with droplets during coughing, sneezing, touching with contaminated hands or materials and from dirty surfaces at any point of placement. These was also shown by Ahmed et al. (2010) and Barolia et al. (2011). The Food and Agriculural Organization (2011) also suggested the persistence and growth ability of generic E. coli in many on foods. Thus, currency used for food marketing can acquire microbial including E. coli from already contaminated food items. Poor storage and handling, and frequent manual count activities also enhance currency cross contamination. Lamichane et al. (2009) and Sanjogita and Geeta (2014) provided similar suggestions.

With regards to specific ETB notes, E. coli harboring rate ranged from 60 to 85 % showing high and similar exposure of most currency denominations. The relatively lower prevalence on Birr 100 and Birr 50 than other denomination (the Birr 1, Birr 5 and Birr 10) are similar with previously reported from Jimma (13.4 % Enterobacteriaceae) by Girma et al. (2014) and from Axsum by Saripalli et al. (2014), both in Ethiopia. This could be due to frequent uses and high accesses of the latter notes which increase the risk of exposure for contamination. Diseases can spread through contact with fomites such as currency notes (Awel et al. 2010; El-Dars and Hassan 2005; Feglo and Nkansah 2010; Michaels 2002; Pope et al. 2002).

High susceptibility (97.7–100 %) of the tested isolates to chloramphenicol, oxytetracycline, trimethoprim-sulfamethoxazole and polymyxin-B indicated the efficacy of these drugs for the treatments of E. coli infection. High and similar susceptibility of E. coli to most of these drugs were also reported by Hiko et al. (2008) and Kibret and Abera (2011) in Ethiopia. However, the significantly high (83.7 %) resistance to neomycin could be due to frequent use the drug in medical sectors leading to development of resistant strain that contaminate the currency from such personnel.

It was concluded that, the food which had already contaminated can be further act as source of contamination of currency used for exchange purposes among various food handlers. Again, contaminated currency can act as serious source for likelihood of harmful microbial including pathogenic E. coli strains. Theses may leads to cross-transmission of ready-to-eat food items such as fruits, bread and the related with possibility of consumer infection. Thus, regular disinfection, use of banks, post offices and ATM with local languages, as well as application of ultraviolet light and fumigation, with parallel replacement of damaged and worn-out notes and education of food handlers were recommended to reduce contamination. The study also provides information on the likely choice of therapeutic antimicrobial agent for infections that might arise from this organism in the area. Further study on the prevalence of other microbial on currency including on coins at other part of the country were also recommended.