Public health officials in Ottawa are investigating a second probable case of West Nile Virus this summer.

The first case went public a week ago but it has not been confirmed. If either case is confirmed, that would be the first human case in Ottawa since 2006.

West Nile is transferred through mosquitoes that carry the virus, but officials say most individuals who are exposed show no symptoms.

The first case is an elderly resident, but there are few details released about the latest case.

Recommended preventive measures include:

• Using mosquito repellent with DEET.
• Wearing long-sleeved light-coloured shirts and pants.
• Make sure that door and window screens fit tightly and have no holes that may allow mosquitoes indoors
• Roughly 20 per cent of people who are infected may show some flu-like symptoms such as headaches, muscle aches and pain.

Medical Officer of Health Isra Levy said Ottawa's worst tally was seven or eight years ago, when there were three confirmed cases.

"There are a lot of predictions that say this might be the worst year we do see by the time it's behind us," said Levy.

"Certainly we're doing everything we can to be sure that isn't the case."

Levy said people should replace water in bird baths, circulate it in fish ponds, and poke holes in outdoor containers so water drains.

The city confirmed last month the presence of West Nile in the mosquito population.

Health officials across Ontario and in several other provinces have warned about an increase in mosquitoes carrying the virus.

Toronto Public Health said the city has seen 38 human cases this summer as of Aug. 27.