The ostrich is susceptible to microorganisms of bacterial, fungal and parasitic origin. Anthrax, caused by Bacillus anthracis , is dangerous to other livestock and humans. Salmonella is transmitted from rodents or wild bird reservoirs. Pausterellosis caused by Pasteurella multocida results in air sac infections in ostriches. Colibacillosis is caused by Escherichia coli . Tuberculosis caused by Mycobacterium avium , is very rare in ostriches. Aspergillosis principally afflicts chicks. Zygomycosis, a secondary fungal infection of the upper gastrointestinal tract, is caused by Basidia , Mucor and Rhizopus . Leucocytozoon struthionis and Plasmodium spp. are harmless protozoa transmitted from flying arthropods. The tapeworm, Houttuynia struthionis , is dangerous in young ostriches. The adult ratite fluke ( Philophthalmus gralli ) is transmitted to ostriches following ingestion of infected freshwater crustaceans. Tick infestations of ostrich skin in Africa include Amblyomma spp., Haemaphysalis punctata , Hyalomma spp., Rhipicephalus turanicus and Argus spp. The ostrich quillmite ( Pterolichus bicaudatus ) and louse ( Struthioliperus struthionus ) may lower skin and leather quality via pruritis and/or excessive preening and feather loss. Nemododa infections are rare.