Northern California tick season is in full-swing, and the creepy crawlers will be out in droves after a rainy winter.

While ticks are active year-round in California, their numbers peak from April to June, and the tiny arachnids are nearly impossible to avoid when outside, says Wendy Adams, the research grant director at the Bay Area Lyme Foundation.

Record rainfall this season complicates matters. The Eight-Station Index, a measure of Northern Sierra precipitation that helps determine statewide water levels, has deemed 2017 the wettest year on record at 92.8 inches. California's open spaces are now covered with leaf litter and fallen logs – the preferred residences of ticks.

A greater abundance of vegetation leads to an increase in wildlife, which means ticks have an ample food supply to choose from. As is the case with most creatures, well-fed ticks reproduce more.

Adams says she can't yet quantify the increase in the tick population as it is early in the season, but anecdotally, the Lyme Foundation lab has noticed an increase in specimens sent to their free tick-testing program. The increase, notes Adam, could be attributed to greater awareness of the program rather than a spike in population.

Back to Gallery Nasty tick season could follow heavy NorCal rains 26 1 of 26 Photo: Contributed Photo 2 of 26 3 of 26 4 of 26 Photo: David Assman / Special to The Chronicle, Tom Stienstra 5 of 26 Photo: Donna Pomeroy/iNaturalist.org 6 of 26 Photo: CHRIS STEWART 7 of 26 8 of 26 Photo: Michael Short, Special To The Chronicle 9 of 26 Photo: / 10 of 26 Photo: Michael Macor / The Chronicle 2017 11 of 26 Photo: Billy Calzada, San Antonio Express-News 12 of 26 Photo: Bill Diller/For the Tribune 13 of 26 Photo: Carolyn Kaster/AP 14 of 26 15 of 26 Photo: D. ROSS CAMERON, Special to The Chronicle 16 of 26 Photo: Frederick Larson 17 of 26 18 of 26 Photo: Point Reyes National Seashore 19 of 26 Photo: KTVU / KTVU 20 of 26 21 of 26 Photo: Jen Joynt, Special to The Chronicle 22 of 26 Photo: Leah Millis / The Chronicle 2014 23 of 26 Photo: Gabrielle Lurie, Special to The Chronicle 24 of 26 Photo: Santiago Mejia, Special to The Chronicle 25 of 26 26 of 26 Photo: Petty Officer 2nd Class Chris Parrinello/AP



















































As the sunshine pulls Northern Californians outdoors, Adams advises taking extra caution to avoid ticks, especially the Western black-legged variety – a known carrier of Lyme disease.

See also: This week's Bay Area weather forecast

A bacteria called Borrelia burgdorferi causes the infection and, if failed to be treated early, can lead to pain and fatigue "on par with that seen in multiple sclerosis," according to LymeDisease.org.

That which we love about California – its biodiversity – leads to difficulty in diagnosing and treating Lyme disease. The diagnostic test fails in 60 percent of cases and 20 percent of patients do not respond to treatment.

Adams cites the Marin Headlands, Olompoli State Park and Windy Hill in Portola Valley as known tick hotspots, but as Stanford researchers discovered in 2014, the arachnids are widespread in California.

See also: Lyme disease more common in Bay Area than previously thought

While Adams does not recommend skimping on your outdoor recreation, she does suggest taking certain precautions, including:

Walking in the middle of trails

Using insect repellant

Tucking pants into socks

Immediately removing hiking clothes upon return and placing them in the dryer for 5-10 minutes

Taking a shower

Conducting a "tick check" with the help of a friend

Symptoms of Lyme disease include a rash around a target-shaped rash around the bite – though rashes only develop in certain cases – headache, sore neck, fever, chills, muscle aches, and joint aches.

"The longer you wait to get symptoms checked, the more the pathogen can invade your body," said Adams. "You have to nip it in the bud."

Read Michelle Robertson’s latest stories and send her news tips at mrobertson@sfchronicle.com.