parasite

parasite A plant or an animal organism that lives in or on another and takes its nourishment from that other organism. Parasitic diseases include infections that are due to protozoa, helminths, or arthropods. For example, malaria is caused by Plasmodium, a parasitic protozoa.

paraquat lung

paraquat lung Lung disease caused by the contact herbicide paraquat, which selectively accumulates in the lungs and is highly toxic. The prognosis depends upon the severity of exposure. Paraquat lung is rare because the herbicide must be directly inhaled to cause the disease. Paraquat lung emerged as a health concern in the 1970s, when the…

paraphimosis

paraphimosis An emergency condition in which the foreskin of the penis, once retracted, cannot return to its original location. The foreskin remains trapped behind the groove of the coronal sulcus, between the shaft and the glans. This causes blood to pool in the veins behind the entrapment, leading to swelling and severe pain. Treatment involves…

paraphilia

paraphilia One of several complex psychiatric disorders that are manifested as deviant sexual behavior. For example, in men, the most common forms are pedophilia (sexual behavior or attraction toward children) and exhibitionism (exposing one’s body in a public setting). Other paraphilias include compulsive sexual behavior (nymphomania), sadism, masochism, fetishism, bestiality (zoophilia), and necrophilia. Treatment may…

paramyxovirus

paramyxovirus One of a group of RNA viruses that are predominantly responsible for acute respiratory diseases and are usually transmitted by airborne droplets. The paramyxoviruses include the agents of mumps, measles (rubeola), RSV (respiratory syncytial virus), Newcastle disease, and parainfluenza.