MANILA, May 22 (Xinhua) -- Health officials went on alert after the first A/H1N1 flu case was confirmed in the Philippines, a World Health Organization (WHO) official said on Friday.

    They are working to trace people that were in close contact with the 10-year-old patient who was tested positive for the virus on Thursday.

    The parents of the Filipino girl are already in quarantine while their other 18 family members are also under observation, WHO country representative Dr. Soe Nyunt-U told reporters.

    Health officials are trying to detect the passengers on the same flight with the young patient when they arrived on May 18 from the United States.

    Despite the case, health officials said that the spread of the virus can be slow in the Philippines thanks to its tropical climate. The virus in tropical or warm countries can only live up to maximum of 12 hours outside the human body while countries with a cold climate will keep the virus alive up to 24 to 48 hours, said the WHO expert.

    Health experts do not advise to close schools or postpone classes in the Philippines as "there is no proof of community-level outbreak," but the public -- especially the students -- are suggested to remain vigilant and hygienic. Young children are more prone to the disease since they have weaker immune systems.

    "There is no guarantee that this will be the first and last case in the Philippines," Dr. Soe said, referring to the A/H1N1 flu case found on Thursday.

    The vaccine for seasonal flu is not effective as prevention for the A/H1N1 virus, said the doctor. The WHO has formed an influenza center, trying to come up with a proper vaccine but it will be made available five to six months from now since the vaccine requires more animal testing before being proved effective in human bodies.

Dr. Julie Hall (R), an expert on Emerging Infectious Diseases, explains various ways of contracting the A/H1N1 Influenza virus now spreading among humans in the World Health Organization (WHO) Western Pacific Office in Manila, capital of the Philippines, May 22, 2009. The spread of the influenza A/H1N1 virus may pick up in the Asia Pacific region with the onset of southern winter and the threat joined by the spread of seasonal influenza might take a heavy toll on countries' health system, the regional World Health Organization (WHO) expert warned Friday. (Xinhua/Luis Liwanag) Photo Gallery>>>

Special Report:  World Tackles A/H1N1 Flu