There are now four presumptive cases of the coronavirus with no known origin in the United States — one in Oregon, one in Washington state, and two in Northern California — and the Centers for Disease Control said in a state Friday that "unprecedented efforts have been taken to contain the spread."The patients tested positive locally, though they are still awaiting confirmation from the CDC. Most of the 67 confirmed cases in the United States so far have been traced to travel to Asia (the disease originated in Wuhan, China), but the four cases mentioned have occurred without any related travel history. Instead they're being labeled as "community spread" cases, though the extent is unclear.The CDC is now working to increase the number of labs who can test for the virus after it expanded its testing guidelines to include people showing symptoms despite not having an identified source of exposure. Additional testing kits have already arrived in California, but some were flawed, delaying labs' ability to administer the test. "This has not gone as smoothly as we would have liked," said Dr. Messonnier, the director of the CDC's National Center for Immunization and Respiratory diseases. Read more at CNN and NBC News.More stories from theweek.com Stock markets are headed for a 40 percent plunge, says economist who predicted financial crisis Exit polls show South Carolina's black voters overwhelmingly backed Biden The growing viral threat