A woman overcome by heat near a cooling center in Ypsilanti on Thursday afternoon ended up being taken to the hospital by Huron Valley Ambulance, part of an uptick in ambulance runs related to the ongoing heat wave.

The incident occurred near the Washtenaw County Public Health Human Services building, 555 Towner St.

“They seem to be all over the county, although there is a higher concentration in the (Ann Arbor) Art Fair area,” said Joyce Williams, a spokeswoman for HVA, said of the increase in ambulance runs that's occurred in recent days.

St. Joseph Mercy Health System and the University of Michigan Health System saw an increase in patients with heat-related illness Wednesday and Thursday, officials there said.

The U-M Emergency Department saw three minor to moderate cases of heat-related illness specifically related to the Art Fair on Thursday, as well of a handful of additional cases from elsewhere.

Three patients arrived at St. Joe’s this week seeking medical treatment for dehydration and cramping, symptoms of heat exhaustion, said Lauren Jones, spokeswoman for the health system.

In the case of the Ypsilanti woman near the Towner Street cooling center, passersby saw the woman struggling outside, escorted her in and called 911, said Susan Cerniglia, a health officer and public information officer for the Health Department.

The woman didn’t make it inside to cool off before becoming ill, but dozens of others did, Cerniglia said, taking advantage of air conditioning and free water and juice.

As part of an emergency response plan activated Tuesday, Washtenaw County staff opened cooling centers from 9 a.m. to 6 p.m. Thursday at 555 Towner and in the Washtenaw County Office Building, 200 N. Main St. in Ann Arbor.

The Main Street location drew a handful of visitors Thursday, said Marc Breckenridge, emergency services director of the Washtenaw County Sheriff’s Office.

Health officials continue to remind residents to exercise care in the face of extreme heat by drinking plenty of water and taking frequent breaks from the heat by sitting in the shade or in air-conditioning. Residents should reschedule strenuous outdoor activities for early morning or evening, learn signs and symptoms of heat exhaustion and heat stroke and wear lightweight or loose clothing, health officials said.

Heat-related illness and symptoms of heat-related illness entail:

• Heat cramps are muscular pains and spasms due to heavy exertion and an early signal that the body is having trouble with the heat.
• Heat exhaustion occurs when people exercise heavily or work in a hot, humid place where body fluids are lost through heavy sweating. Blood flow to the skin increases, causing blood flow to decrease to the vital organs. This results in a form of mild shock. If not treated, the victim may suffer heat stroke. Signals of heat exhaustion include cool, moist, pale flushed or red skin; heavy sweating; headache; nausea or vomiting; dizziness; and exhaustion. Body temperature will be near normal.
• Heat stroke, or sunstroke, is life-threatening. The victim's temperature control system, which produces sweating to cool the body, stops working. The body temperature can rise so high that brain damage and death may result if the body is not cooled quickly. Signals include hot, red and dry skin; changes in consciousness; rapid, weak pulse; and rapid, shallow breathing. Body temperature can be very high—sometimes as high as 105 degrees.

Juliana Keeping covers general assignment and health and the environment for AnnArbor.com. Reach her at julianakeeping@annarbor.com or 734-623-2528. Follow Juliana Keeping on Twitter