Contact tracing, a public health tool challenged by coronavirus, faces new test in Nevada and its casinos Megan Messerly and Jackie Valley, The Nevada Independent · June 29, 2020 at 6:53 am Long before contact tracing became the stuff of household conversations, it was a crucial but unassuming tool used by rank-and-file public health professionals to track down some of the most pernicious communicable diseases. Contact tracing responsibilities within the Southern Nevada Health District were, for instance, divided into several groups. There was the group that investigated sexually transmitted diseases, including HIV. There was the tuberculosis group. Then, there was the everything else group: Salmonella, shigella and campylobacter, three types of bacteria, the most common among them. For the most part, those diseases were fairly straightforward to trace. With those that were harder, like measles and pertussis, or whooping cough, which spread easily among people and require extensive contact tracing, there weren’t that many cases, and much of the population is immune because of vaccinations. Plus, at least there was a rule book for it.