Researchers at the University of Pretoria, South Africa, have found disease-causing bacteria on leafy vegetables from both commercial and informal farms. The pathogens have been linked to irrigation water sourced from rivers and boreholes, with nearly half of the samples showing resistance to at least three antibiotics.
Professor Lise Korsten told Parliament's Agriculture Portfolio Committee that irrigation water in South Africa is "not fit-for-purpose" for food production. She called for urgent national attention to improve water quality, warning that contaminated water poses serious food safety and public health risks.
Multiple studies by the university link irrigation water to contamination in Gauteng, Limpopo, North West, and the Western Cape. One 2021 study on spinach farms in Gauteng found 80 different types of E. coli and Salmonella in irrigation water and produce. Some strains contained the stx2 gene, known to cause severe illness. Of the 288 samples collected, 76 E. coli types were resistant to at least one antibiotic, and 35 were resistant to three or more.
Contamination stems from widespread sewage pollution. South Africa's Department of Water and Sanitation reports that 81% of sewage treatment plants fail to meet microbiological standards. Major rivers used for irrigation, such as the Vaal, Klip, Crocodile, and Olifants, receive millions of litres of poorly treated or untreated sewage daily. For instance, Cape Town's Athlone plant, with a 4% compliance rate, releases up to 105 million litres of effluent into the Black River every day.
Professor Marc Mendelson of the University of Cape Town warns that antibiotic resistance is reaching a crisis point. With fewer effective antibiotics available, common infections are becoming harder to treat. Mendelson highlighted that even well-run treatment plants are not equipped to filter out antibiotic-resistant bacteria.
He urged improvements in sanitation and access to clean water, noting that these would significantly reduce disease and antibiotic resistance. In the meantime, consumers are advised to wash or cook vegetables thoroughly before consumption.
The contamination issue also threatens South Africa's agricultural exports. ActionSA MP Athol Trollip expressed concern about potential damage to the citrus export market, which generated R33 billion ($1.78 billion) last year. A single outbreak linked to contaminated produce could lead to trade bans, particularly in the tightly regulated European market.
Trollip warned of severe economic and employment consequences if exports were jeopardized. He criticized the lack of accountability for failing sewage systems and described the pollution of water used for drinking, farming, and livestock as a ticking time bomb.
Source: GroundUp