Malaria recrudescence is- a) Resistant to treatment b) Relapse of infection c) Relapse in vivax and ovale d) Re-appearance of asexual stage parasitaemia after treatment. Answer: Re-appearance of asexual stage parasitaemia after treatment Explanation: In infections involving P. vivax and P. ovale there may be persistent hypnozoites in the liver. They are responsible for relapses of those species for periods of up to 8 or 9 years. The term for recurrence of infection with other species, P. falciparum, P. malariae and P. knowlesi, which lack hypnozoites, is “recrudescence”, meaning that the infection has recurred from persistent blood stages of the malaria parasite. There are several studies to prove that recurrent P. falciparum infection is caused by recrudescence of chloroquine resistant parasites. “Recrudescence” can also occur with P. vivax and P. ovale infections when such parasites have also persisted in the blood. Recrudescence can be due to (1) incomplete or inadequate treatment as a result of drug resistance or improper choice of medication, (2) an antigenic variation, and (3) multiple infections by different strains.