The fifth Phylum of the Protist Kingdom, known as Apicomplexa, gathers several species of obligate intracellular protozoan parasites classified as Sporozoa or Sporozoans, because they form reproductive cells known as spores. Many sporozoans are parasitic and pathogenic species, such as Plasmodium (P. falciparum, P. malariae, P. vivax), Toxoplasma gondii, Pneumocysts carinii, Coccidian, Babesia, Cryptosporidum (C. parvum, C. muris), and Gregarian. The Sporozoa reproduction cycle has both asexual and sexual phases. The asexual phase is termed schizogony (from the Greek, meaning generation through division), in which merozoites (daughter cells) are produced through multiple nuclear fissions. The sexual phase is known as sporogony (i.e., generation of spores) and is followed by gametogony or the production of sexually reproductive cells termed gamonts. Each pair of gamonts form a gamontocyst where the division of both gamonts, preceded by repeated nuclear divisions, originates numerous gametes. Gametes fuse in pairs, forming zygotes that...