Parasites can increase infection rates andpathogenicity in immunocompromised humanimmunodeficiency virus (HIV) patients. However, invitro studies and epidemiological investigationsalso suggest that parasites might escapeimmunocompromised hosts during HIV infection.Due to the lack of direct evidence from animalexperiments, the effects of parasitic infections onimmunocompromised hosts remain unclear. Here,we detected 14 different parasites in six northernpig-tailed macaques (NPMs) before or at the 50thweek of simian immunodeficiency virus (SIV) infectionby ELISA. The NPMs all carried parasites before viralinjection. At the 50th week after viral injection, theindividuals with negative results in parasitic detection(i.e., 08247 and 08287) were characterized as theParasites Exit (PE) group, with the other individuals(i.e., 09203, 09211, 10205, and 10225) characterizedas the Parasites Remain (PR) group. Compared withthe PR group, the NPMs in the PE group showedhigher viral loads, lower CD4 + T cells counts, andlower CD4/CD8 rates. Additionally, the PE group hadhigher immune activation and immune exhaustion ofboth CD4 + and CD8 + T cells. Pathological observationshowed greater injury to the liver, cecum, colon,spleen, and mesenteric lymph nodes in the PE group.This study showed more seriously compromisedimmunity in the PE group, strongly indicating thatparasites might exit an immunocompromised host.