Polycystic kidney disease can cause abdominal pain, headaches, and pain in the sides and back. Porphyria is a condition that can affect the nerves and skin, making the skin extremely sensitive to sunlight. Hydronephrosis is a condition of the kidneys and causes aching or pain, urinary symptoms, fever, and nausea.
Protozoan infections are parasitic diseases caused by organisms formerly classified in the Kingdom Protozoa. They include organisms classified in Amoebozoa, Excavata, and Chromalveolata. Examples include Entamoeba histolytica, Plasmodium (some of which cause malaria), and Giardia lamblia. Trypanosoma brucei, transmitted by the tsetse fly and the cause of African sleeping sickness, is another example.
Several human diseases caused by protozoa are transmitted by a variety of arthropod vectors (Table). The vectors are not simply 'flying syringes', but represent a second host for the protozoan parasite. Thus the life cycle of vector transmitted diseases also involves complex interactions protozoan-vector interaction analogous to the complex human-protozoan interactions. Vector transmission probably evolved multiple times.