In parasitology superinfection refers to reinfection of same species of parasite. Strategies to reduce recurrence rates of HIV have been successful in preventing reinfection. Other important issues related to the treatment of hookworm are reinfection and drug resistance. Surgery for anorectal fistulae is not without side effects, including recurrence, reinfection, and incontinence. Depending upon the cause, recurrence can be classified as either recrudescence, relapse, or reinfection. Light infections are usually left untreated in areas where reinfection is common. For people having had measles, it is rare to ever have a symptomatic reinfection. Contracting the CTF virus is thought to provide long-lasting immunity against reinfection. Upon reinfection, IgM antibodies usually do not rise again but IgG levels will increase. Without reinfection, the inflammation will gradually subside. People receiving treatment should be advised that reinfection is possible and how to prevent it. If the risk of reinfection is high, screening can be repeated throughout pregnancy. Good hygiene is necessary to avoid reinfection. Following treatment people should be tested again after three months to check for reinfection. It has been shown that reinfection after treatment can be extremely high.