The rate of COVID-19 in Sarnia-Lambton is the third highest among Ontario’s 34 health units, the province reported Tuesday.

Why is a little harder to grasp, said Dr. Sudit Ranade, Sarnia-Lambton’s medical officer of health.

Public Health Ontario’s daily epidemiological report had the Lambton public health region with 117 confirmed cases for a rate of 89.3 per 100,000 population, as of 4 p.m. on April 13.

Windsor-Essex was right behind, with 306 cases and a rate of 72 per 100,000 population.

The relatively high numbers, Ranade said, could be a result of adjacency to major land border crossings and airports. He also suggested the higher rate could stem from Lambton having an older-than-average population that’s more afflicted with underlying chronic health conditions than the rest of the province.

It also could have something to do with major outbreaks in long-term care and retirement homes, Ranade said.

Such outbreaks have happened in homes in Lambton, Haldimand-Norfolk, and Leeds, Grenville & Lanark, the top three health unit regions for COVID-19 rates in Ontario.

“When you look at it, it’s tempting to say there must be a reason,” Ranade said about the numbers, “but when you delve into it, there are a few reasons, but it would be hard to say which one of them was more important, or the real one.”

It’s important to look at the numbers with caution, he said.

“Especially as they will continue to evolve.”

Lambton’s number of COVID-19 cases climbed to 119 Tuesday, including 11 deaths and 21 recoveries.

An outbreak at Landmark Village retirement home in Sarnia accounts for 23 confirmed cases and six deaths.

tkula@postmedia.com

TOP COVID-19 RATES IN ONTARIO

• Leeds, Grenville & Lanark District Health Unit: Rate per 100,000 – 119.0
• Haldimand-Norfolk Health Unit: Rate per 100,000 – 113.1
• Lambton Public Health: Rate per 100,000 – 89.3
• Windsor-Essex County Health Unit: Rate per 100,000 – 72.0
• Toronto Public Health: Rate per 100,000 – 68.8

SOUTHWESTERN ONTARIO

• Chatham-Kent Public Health: Rate per 100,000 – 23.5
• Grey Bruce Health Unit – 21.8
• Huron Perth Public Health – 22.2
• London-Middlesex Health Unit: Rate per 100,000 – 47.5
• Southwestern Public Health: Rate per 100,000 – 16.1
• Total South West (including Lambton and Windsor-Essex): Rate per 100,000 – 46.8