(Inside Science) -- When Shannon Heineman saw a rash around her daughter’s ear she suspected it was Lyme disease.
"She was a perfect case of the target rash," said Heineman.
This telltale target rash is often one of the first symptoms of Lyme disease -- a bacterial infection transmitted by a black-legged tick or deer tick bite. Recently, epidemiologists have seen an increase in the number of reported cases.
"Over the years we have seen the total number of cases increase fairly dramatically from a few thousand to roughly 30,000 per year now," said Paul Mead, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta, Ga.
Now, researchers are looking at how weather affects when tick populations are at their peak and which months of the year people are more likely to be infected with Lyme disease.
"They [ticks] can be influenced in terms of their activity by things such as temperature and moisture," said Mead.
Most cases of Lyme disease occur in the late summer months when ticks are most active. But as the spring months become warmer and drier, ticks may be more active earlier in the year just when people start spending more time outdoors leading to more cases of Lyme disease.
"If we can figure out when these ticks are most active then health officials can target their messages and other prevention efforts to that time when they would be most effective."
The most common symptoms of Lyme are fever, headache and fatigue. If left untreated, the infection can spread to the joints, heart and nervous system.
Experts say the best way to prevent tick bites is to apply insect repellent containing DEET, wear long clothing and shower after being outdoors.
Editor's note: Shannon Heineman is the sister-in-law of this story's producer, Karin Heineman.