A tick bite that is 15 days old is not necessarily past the danger period, which usually falls after 20 days. Tick bites are dangerous for 24 to 48 hours and have an incubation period of 3 to 20 days. After being bitten by ticks for 15 days, the incubation period has not been fully passed, so there is still a certain degree of danger, but if the body does not have any uncomfortable symptoms and the skin at the bite site returns to normal, most of the time there will be no further danger. If symptoms occur, there will be localized erythema, fever, malaise, headache, nausea and vomiting, and difficulty breathing. If you are bitten by a tick, you should go to the hospital in time for treatment, clean and disinfect the wound, and prevent complications such as infected ulcers at the bite site. Seek medical attention as soon as possible if you experience any discomfort, so as not to affect your health.