Listeriosis is an infectious disease that is caused by Listeria monocytogenes. In the US, about 1600 people are infected each year. According to the Centers for Disease Control and Prevention, it is usually transmitted by eating foods such as raw meat as well as milk contaminated with Listeria monocytogenes. Because this bacteria is able to survive in cold, dry and warm environment, its control is not easily achieved, although it can be destroyed by cooking at high temperatures and pasteurization. There are no vaccinations for listeriosis which can affect almost everyone. However, listeriosis primarily affects pregnant women, newborns, older adults, and people with weakened immune systems. Prolong infection in the above-mentioned population groups can result in either a sepsis (severe infections of the bloodstream), meningitis (inflammation of the membranes surrounding the brain and spinal cord) or encephalitis (inflammation of the brain). In pregnant women, listeriosis is known to be associated with miscarriage, stillbirth, or infant mortality. The incubation period of listeriosis varies between 3 to 70 days. When infected with listeriosis, hospitalization is usually required and treatment usually involves the use of antibiotics. The case fatality for this infection is estimated to be about 20% but estimates as high as 80% has been reported. Listeria infection is diagnosed through blood or stool cultures, with the former being considered as the gold standard and preferred over other invasive techniques like isolation from cerebrospinal fluid or amniotic fluid. It takes about 24-48 hours to culture the bacteria after which additional tests may be performed which means that the total time to identification could take anywhere from 2 to 7 days. Genetic analysis may be conducted to reduce this time but it also comes at a higher cost.

Listeria monocytogenes can also be detected in urine. You as a highly esteemed epidemiologist was paired with a team of microbiologists and other biomedical scientists who successfully developed a test that detects listeria from urine samples. Such a relatively cheap and noninvasive test, if accurate could cut down the diagnosis time for listeria. Also, this urine test can be used at home which could lead to early treatment. Discuss what type of screening program you will implement with this new screening tool. Assuming that you can achieve either a high sensitivity (>90%) or a high specificity (> 90%) but not both with the new urine test, discuss which one of these two measures you will prioritize. Please provide reasons/rationale for your choices.