Cattle infected with a common parasite could be spreading TB across Britain undetected. Bovine tuberculosis (bTB) could be spreading across Britain because the most widely used test for the disease is ineffective when cattle are infected with a common liver parasite. The liver fluke Fasciola hepatica was already known to affect the standard skin test for bTB, but it was unclear whether the fluke stopped the disease developing or merely hid the symptoms. A study published today in Nature Communications suggests that the latter is more likely, and that the effect is significant. It estimates that around a third of...