U.S. health officials reported Friday a fourth case of the novel coronavirus of unknown origin, indicating that the disease was spreading in the country. The latest case is a boy under 18 in Washington State who tested "presumptive positive," local authorities said without releasing further details about the patient.

The U.S. Centers for Disease Control and Prevention (CDC) issued a statement on Friday, saying that the center is aware of four new presumptive positive cases of COVID-19, announced by state public health authorities who are currently conducting investigations. The cases are as follows:

- California has announced a second possible instance of community spread.

- Oregon has announced its first possible instance of community spread.

- The state of Washington has announced two presumptive cases. One is likely to be travel related. The other is the state's first possible instance of community spread.

Community spread means spread of an illness of which the source of infection is unknown, explained the CDC. One previous possible instance of community spread was announced in California on February 26, it added.

In a White House press conference on Wednesday, U.S. President Donald Trump said, "We are very, very ready for this, for anything whether it's going to be a breakout of larger proportion, or whether or not we're at that very low level."

(Cover: The NorthBay VacaValley Hospital, where a woman diagnosed with coronavirus infection previously sought treatment, in Vacaville, California, U.S., February 27, 2020. /AP)