GENEVA - The head of the World Health Organization says he fears the increase in the number of cases of coronavirus in Iran could be a signal of worse things to come. Iran has reported 18 cases, including at least five deaths in the past two days.

The number of cases and deaths reported in Iran still pales in comparison to that recorded in China.

But WHO chief Tedros Adhanom Ghebreyesus expressed concern about the number of cases in countries outside of China that have no clear epidemiological link, such as travel to China.

"There is a case which is linked to Iran now in Lebanon. This is a 45-year old woman. And, those [cases] are actually very concerning. Take them as trends. So, what I believe is the window of opportunity [for containment] is still there. But ... our window of opportunity is narrowing."

Tedros urged countries to act now to contain the coronavirus, before the window of opportunity closes. Currently, some 30 countries report cases of the virus, and at least 18 people outside China have died. South Korea has the largest cluster of confirmed cases outside China.

WHO: Time Is Running Out to Stop Spread of Coronavirus Virus spreads in Middle East, South Korea, Italy

Tedros said this is no time for pessimism, but for action. He said the WHO is coordinating a global response that can defeat this disease.

"The measures China and other countries have taken have given us a fighting chance of containing the spread of the virus... We must not look back and regret that we failed to take advantage of the window of opportunity that we have now," Tedros said.

The WHO chief spoke in Addis Ababa, Ethiopia, attending an emergency meeting on COVID-19. It is organized by the African Union and the African Centers for Disease Control and Prevention.

The WHO is working to try to prevent COVID-19 from gaining a foothold in the developing world. It is focusing efforts on strengthening fragile health systems on the African continent and other vulnerable regions.

Egypt is the only African country with a confirmed case of coronavirus. The WHO reports suspected cases of COVID-19 in several other African countries have been tested and proved to be negative.