Psittacosis known serovars. All should be considered to be readily transmissible to humans. "C. psittaci" serovar A is endemic among psittacine birds and has caused sporadic zoonotic disease in humans, other mammals, and tortoises. Serovar B is endemic among pigeons, has been isolated from turkeys, and has also been identified as the cause of abortion in a dairy herd. Serovars C and D are occupational hazards for slaughterhouse workers and for people in contact with birds. Serovar E isolates (known as Cal-10, MP, or MN) have been obtained from a variety of avian hosts worldwide, and although they were associated with
Niemann–Pick disease bone called coxa vara. Sleep-related disorders, such as sleep inversion, sleepiness during the day and wakefulness at night, may occur. Gelastic cataplexy, the sudden loss of muscle tone when the affected patient laughs, is also seen. Mutations in the "SMPD1" gene cause Niemann–Pick disease types A and B. They produce a deficiency in the activity of the lysosomal enzyme acid sphingomyelinase, that breaks down the lipid sphingomyelin. Mutations in "NPC1" or "NPC2" cause Niemann–Pick disease, type C (NPC), which affects a protein used to transport lipids. Type D originally was separated from type C to delineate a group of patients