Metro Manila (CNN Philippines, March 11) — The number of foreign nationals who have tested for the coronavirus disease (COVID-19) after visiting the Philippines has risen to six.

The Department of Health in a House hearing on Wednesday disclosed that aside from the three foreigners earlier reported, three more foreign visitors were found to have COVID-19 after leaving the Philippines.

“We [now] have six confirmed cases of foreign nationals having history of travel in the Philippines,” Health Secretary Francisco Duque III said.

The new cases include a Japanese national who is currently being treated for coronavirus after staying in the Philippines for seven to nine days, Duque said. Another is a Singaporean national who tested positive for coronavirus abroad after staying in the country for three days.

A South Korean "with extensive travel history" was also found to have contracted the virus after leaving the Philippines.

The DOH earlier confirmed that a 38-year-old Taiwanese man, 44-year-old Japanese man, and a woman from Sydney, Australia have all tested positive for coronavirus in other countries, and were traced to have been to the Philippines.

The DOH has formed teams to track down people who may have come in contact with the foreign coronavirus patients.

The Philippines has reported a total of 33 coronavirus cases – 30 of them are admitted in hospitals mostly in Metro Manila. The other three are the Chinese visitors who earlier tested positive for the virus in the Philippines – one of them died, while the remaining two have since recovered and left the country.

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Worldwide, the COVID-19 has killed more than 4,200 people, mostly in China, since the outbreak began in Wuhan City in Hubei province in December last year. It has infected over 115,800 people worldwide.

According to the World Health Organization, the most commonly reported symptoms are fever, dry cough and shortness of breath. WHO said 8 in 10, or around 80 percent, of infected patients experience "mild illness" and eventually recover from COVID-19. Some 14 percent experience severe illness while 5 percent were critically ill, the WHO said.

To prevent infection, authorities are urging people to practice regular hand washing, cover the mouth and nose when coughing and sneezing, and avoid close contact with those who show respiratory symptoms.