The death of a 60-year-old man from the Interlake area of Manitoba could be the third in the province this year related to the West Nile virus, health officials said Thursday.

The office of the province's chief medical officer of health is investigating what role, if any, the mosquito-borne virus played in the man's death.

The deaths of two other elderly men — one in his 80s and one in his 70s — have also been connected to West Nile. The virus was likely the cause of one of the deaths; the role the virus played in the other is under investigation.

Over the past week, 90 more positive test results for West Nile were reported in the province, bringing the total number of reported cases in 2007 to a record 445.

Most people who contract West Nile show no signs of the virus. Of those who do, most experience flu-like symptoms such as fever, headaches, fatigue and body aches.

The virus can cause a more serious condition, called West Nile neurological syndrome, which can result in weakness, paralysis, confusion, coma or, in rare cases, death.

Of Manitoba's cases to date this year, 139 have been scrutinized and classified, of which 32 were found to be the more serious neurological syndrome.

Health officials believe most of the cases stem from exposure before mid-August to infected mosquitoes.

Although mosquito activity may appear to be low now, health officials warn that the risk of exposure to West Nile virus has not yet ended for the summer. Infected mosquitoes are still present in most parts of southern Manitoba, although their numbers are decreasing.

As the weather cools, the mosquitoes that carry the virus may become more active in the afternoon and early evening, health officials said, rather than from dusk to dawn.

People can reduce their exposure to the virus by curbing the amount of time spent outdoors when mosquitoes are active and by wearing mosquito repellent and light-coloured, loose-fitting clothing.