TUNISIA – A study has revealed a high rate of Brucella contamination in dairy products in Tunisia, shortly after another study conducted in Kenya discovered a cocktail of micro-organisms in milk.
The study investigated the occurrence of Brucella in 200 raw milk, ricotta, and artisan fresh cheese samples, collected from four districts in Tunisia.
Brucellosis is a significant public health threat for urban and rural populations of endemic countries, particularly the Middle East and North Africa region, as the trade of unpasteurized milk and raw dairy products is widespread, says the study.
Samples were purchased from 75 retail marketing points for dairy products from March to November 2019. According to the study published in the journal Foods, forty samples of cow’s raw milk, 102 of artisanal fresh cheese, and 58 of ricotta were collected.
The fresh cheese and ricotta samples were made from unpasteurized cow′s milk. All products were not packaged and had no indication they had been inspected by any Tunisian organization involved in food safety, the research indicated.
Out of the 200 samples, Brucella was spotted in 150 (75%) with Brucella abortus being found in 47 (31.3%) samples, and Brucella melitensis in eight (5.3%). Almost half of the tested products had both species, while 21 (14%) were neither Brucella abortus nor melitensis.
The detection of both B. abortus and B. melitensis highlights that zoonotic high-pathogen agent control remains a challenge for food safety and consumer health protection, and could represent a serious emerging foodborne disease in Tunisia.
According to the researchers, the double-contamination was a result of milk pooling, a major practice in Tunisia.
They found that 86.2 percent of ricotta, 69.6 percent of fresh cheese, and 72.5 percent of milk samples were positive.
Brucella contamination rates in the different districts were 94 percent in Tunis, 86 percent in Bizerte, 74 percent in Zaghouan, and 46 percent in Beja, Food Safety News reports.
The samples were collected from early spring to late fall, since it coincided with an overproduction of milk and an increase in dairy product consumption, particularly during the month of Ramadan. Spring and fall are the lambing seasons in Tunisia plus there are higher temperatures.
Besides milk pooling, cross contamination is also a possible source of Brucella spread. This can be through the use of the same milking equipment, containers, and utensils without washing and sterilization measures.
Vendors using the same knives to cut cheese and ricotta and the same pitcher to measure milk might also increase the likelihood of cross-contamination between the different products, the study records.
The scholars have recommended a review of the surveillance system and implementation of control programs to limit and prevent brucellosis infection in ruminant herds.
“Brucellosis infection through the consumption of dairy products is a serious hazard with great public health significance. Our study provides evidence of the high contamination rates with Brucella DNA and the distribution of Brucella species in unpasteurized artisanal dairy products,” they concluded.
In 2017, the incidence of human brucellosis in Tunisia was 9.8 per 100,000 population. In the Douz district, 2 cases were reported in March 2018. Prior to that date, the last indigenous cases to be reported in Douz had been in 2015.
Worldwide zoonotic disease
Brucellosis is a worldwide zoonotic disease transmitted to humans, predominantly by the consumption of brucella contaminated raw milk and dairy products.
Brucella majorly inhabits female mammals’ reproductive tract leading to infertility, placental retention, abortion and stillbirth. It also has a liking for mammary glands and is occasionally excreted in milk.
Brucella melitensis infects mainly sheep and goats and is the species most frequently responsible for human infections.
The transmission between animals occurs mainly through direct contact with infected placenta, genital discharges and through sexual route. The main risk factors include introduction in herds of infected animals or borrowing rams, and co-grazing and contact in watering points.
Animal mass vaccination is the only effective control option leading to prevent humans’ and animals contamination.
Handling female ruminants during abortion or parturition significantly increases the odds of clinical human Brucellosis (CHB), thus awareness and educational programme targeting farmers should be carried out.