After entry, generally through endocytosis or phagocytosis into a membrane-enclosed compartment, intracellular pathogens may use one of three strategies to survive and replicate. Pathogens that follow strategy (1) include all viruses, Trypansoma cruzi, Listeria monocytogenes, and Shigella flexneri. Those that follow strategy (2) include Plasmodium falciparum, Mycobacterium tuberculosis, Salmonella enterica, Legionella pneumophila, and Chlamydia trachomatis. Those that follow strategy (3) include Coxiella burnetii and Leishmania.