Why was this a record year for West Nile infections?
The record-breaking number of West Nile cases in Hamilton this summer may have been due to a lack of public awareness, a West Nile expert says.
"I don’t think people were taking care of themselves," Fiona Hunter, a biological science professor at Brock University and West Nile specialist, said.
The large number of infectious mosquitos was due in part to a long, warm summer, Hunter said. When temperatures are high, the West Nile virus grows more quickly in mosquitos, making them more likely to become infectious and spread the virus, Hunter explained.
Though researchers were aware early, that this summer would yield high numbers of infectious bugs many people were affected this year, including 20 in Hamilton. Hunter suspects this may be because many people weren’t taking precautions seriously, in part due to the low number of cases over the past few years.
"People get tired of seeing messages about protecting themselves," she said. "But this was the year there ought to have been a big campaign."
West Nile numbers climbed to 249 cases in the province this year, including four deaths. Seven of the 20 people infected in Hamilton were hospitalized, though there were no deaths in the area.
Hamilton Public Health Services has been tracking the number of infected mosquito pools, which are groups of adult mosquitos, using traps set up across the area.
Lower East Hamilton and Lower Stoney Creek saw the highest number of West Nile positive pools, with 12 and seven positive tests, respectively.
In part, this is due to a higher number of traps in those areas. Some parts of the city had only one trap, but both Lower East Hamilton and Lower Stoney Creek had four traps.
"Lower Stoney Creek had more traps because it’s a mixed area of residential and wetlands, so we wanted to cover both," said Hamidah Meghani, associate medical officer of health for HPHS.
"Because of that, you’re more likely to get positive results."
Many areas of the city had no positive tests but pockets of multiple infected pools are common, according to Hunter.
"Usually there is a source of infected birds near that area that is causing the area to continually be testing positive," Hunter said.
"We call them hot spots that, for whatever reason, have a source of birds that have been infected."
These hot spots can crop up in a new area every year, Hunter explained, so it’s difficult to pinpoint what causes them.
But even one West Nile positive pool is too many, according to Tara Hall, communications officer for HPHS.
"Once we have one mosquito in one trap, we know we have West Nile in the area and we need to take precautions," Hall said.