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United States Department of Agriculture

Agricultural Research Service

Research Project: PROTOZOAN PARASITES AFFECTING FOOD ANIMALS, FOOD SAFETY, AND PUBLIC HEALTH Title: Coccidia and Other Protozoa

Authors
item Lindsay, David -
item Dubey, Jitender
item Santin-Duran, Monica
item Fayer, Ronald

Submitted to: Diseases of Swine
Publication Type: Book / Chapter
Publication Acceptance Date: February 27, 2011
Publication Date: May 1, 2012
Citation: Lindsay, D., Dubey, J.P., Santin, M., Fayer, R. 2012. Coccidia and Other Protozoa. In: Zimmerman, J., Karriker, L., editors. Diseases of swine. 10th edition. San Francisco, CA: Wiley and Sons, Inc. p. 895-907.

Interpretive Summary: Cryptosporidium species are prevalent and ubiquitous protozoan parasites of vertebrates that cause diarrheal disease. This genus consists of over 20 species and nearly twice that number of genotypes. Some species infect only one host species whereas others are capable of infecting a wide range of hosts. Cryptosporidium suis followed by Cryptosporidium pig genotype II and occasionally C. parvum are the most frequently found species in pigs. Giardia duodenalis is possibly the most common intestinal parasite of humans and livestock worldwide. It is a species complex consisting of seven assemblages (designated A through G) based on genetic differences, whose members are microscopically indistinguishable. Assemblages A and B infect humans and of mammals. Assemblage E infects hooved animals. Assemblages A andE have been identified in pigs in Europe and Australia. There are over1000 species of Microsporidia, a diverse group of obligate intracellular parasites now recognized as fungi. Most infect invertebrates and fish, but several species infect humans, especially immunosuppressed persons. The most commonly found of these, Enterocytozoon bieneusi and the Encephalitozoon species (E. cuniculi, E. intestinalis, and E. hellem), infect humans and other animals. Both E. bieneusi and E. cuniculi have been identified in pigs.

Technical Abstract: Cryptosporidium species are prevalent and ubiquitous worldwide in humans and animals. There are over 20 named species plus nearly twice that number of genotypes and the identification of new species and genotypes continues to evolve rapidly. These obligate intracellular protozoan parasites of vertebrates range from host restricted species to species capable of infecting a wide range of hosts (Fayer, 2010). In pigs the most frequently found species is C. suis followed by Cryptosporidium pig genotype II and occasionally C. parvum, a widespread zoonotic pathogen highly prevalent in young cattle. Giardia duodenalis is possibly the most common intestinal parasite of humans and livestock worldwide. It is a species complex consisting of seven assemblages based on genetic analysis, whose members are morphologically indistinguishable. Assemblages A and B infect humans and a wide range of mammals. Others primarily infect specific groups of animals: C and D infect canids, E infects livestock, F infects felids, and G infects rodents. There are approximately 1200 named species of Microsporidia, a diverse group of obligate intracellular parasites once regarded as protozoa but now recognized as fungi. Most infect invertebrates and fish, but 14 species in 8 genera infect humans and four of these, Enterocytozoon bieneusi and the Encephalitozoon species (E. cuniculi, E. intestinalis, and E. hellem), infect humans and other animals. Swine can serve as a potential source for humans.

Last Modified: 10/20/2014
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