Health officials are reporting a fourth presumptive positive case of coronavirus in Harris County. The patient is described as a man in his 40s who is quarantined at his home in the northwest part of the county. Houston health officials now say a female patient who is the city's second presumptive positive case was at the Houston Livestock Show and Rodeo last Sunday. There are now 18 confirmed or presumptive positive cases of the virus in the Houston area, including Fort Bend and Montgomery Counties.