Health officials in Quezon City have noted a 340-percent surge in leptospirosis cases, particularly after heavy monsoon rain and floods swamped Metro Manila and nearby provinces last month.

Dr. Rolly Cruz, head of the city health department's epidemiology unit, said they noted 346 cases from January to September this year, radio dzBB's Allan Gatus reported.

Cruz was quoted in the report as saying this was a major increase from the 78 cases they recorded in the same period in 2011.

He said this may be partly due to the floods brought by the monsoon rain last August.

The report quoted Cruz as saying many of the cases involved males as young as 20.

Most of the cases were from flood-prone areas including Baesa, Gulod, and Tatalon, it added.

Of these cases, more than 50 were brought to the San Lazaro Hospital in Manila for treatment.

Cruz cautioned residents against dismissing some symptoms of leptospirosis such as coughs and colds as just a case of the flu, adding they should immediately see a doctor.

The US National Library of Medicine said leptospirosis is a rare and severe bacterial infection that occurs when people are exposed to certain environments - such as floodwaters contaminated with animal urine or waste.

Its risk factors include:

Its symptoms can take two to 26 days or an average of 10 days to develop, and may include:

— LBG, GMA News