Virus and Bacteria
Diseases caused by viruses such as chickenpox, rubella, mumps, Epstein-Barr virus, or parvovirus can decrease the platelet count of the body. The people acquiring HIV often develop thrombocytopenia. Mononucleosis or cytomegalovirus can also cause platelet count t decrease. In the same way, bacterial infections that involve blood can also destroy platelets or be a cause of platelet reduction. Widespread bacterial infection can cause blood poisoning, which can lower the platelet count.
Genetic condition
Some genetic disorders also cause a low number of platelets in the blood. These disorders include May-haggling and Wiskott-Aldrich syndrome.