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Canada's National Agri-Environmental Standards Initiative sought to develop an environmental benchmark for low-level waterborne pathogen occurrence in agricultural watersheds. A field study collected 902 water samples from 27 sites in four intensive agricultural watersheds across Canada from 2005 to 2007. Four of the sites were selected as reference sites away from livestock and human fecal pollution sources in each watershed. Water samples were analyzed for Campylobacter spp., Salmonella spp., Escherichia coli O157:H7, Cryptosporidium spp., Giardia spp., and the water quality indicator E. coli. The annual mean number of pathogen species was higher at agricultural sites (1.54 ± 0.07 species per water sample) than at reference sites (0.75 ± 0.14 species per water sample). The annual mean concentration of E. coli was also higher at agricultural sites (491 ± 96 colony-forming units [cfu] 100 mL(-1)) than at reference sites (53 ± 18 cfu 100 mL(-1)). The feasibility of adopting existing E. coli water quality guideline values as an environmental benchmark was assessed, but waterborne pathogens were detected at agricultural sites in 80% of water samples with low E. coli concentrations (<100 cfu 100 mL(-1)). Instead, an approach was developed based on using the natural background occurrence of pathogens at reference sites in agricultural watersheds to derive provisional environmental benchmarks for pathogens at agricultural sites. The environmental benchmarks that were derived were found to represent E. coli values lower than geometric mean values typically found in recreational water quality guidelines. Additional research is needed to investigate environmental benchmarks for waterborne pathogens within the context of the "One World, One Health" perspective for protecting human, domestic animal, and wildlife health.

Key content Postpartum ovarian vein thrombosis (POVT) is a rare but potentially fatal condition. Symptoms up to 4 weeks postpartum often include vague abdominal pain and pyrexia. A high index of suspicion is required to make the diagnosis. As there is no consensus regarding management, a multidisciplinary approach is advised. Learning objectives Recognise the symptoms and signs of POVT and formulate a differential diagnosis. Recognise the importance of imaging in confirming the diagnosis and involvement of the multidisciplinary team to plan management. Understand that conservative management with low‐molecular‐weight heparin is the first‐line treatment, and understand the situations that may require vena caval filter insertion or surgical intervention. Ethical issues How can we counsel women about risks of conservative and surgical management of this condition when there is no consensus for this management? Should women who have had an ovarian vein thrombosis in a previous pregnancy be counselled toward avoiding future pregnancy?

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