Infectious Diseases of the Digestive System. GI Tract. U.S. Foodborne-Disease Outbreaks. Typhoid Mary. Human carrier (and reservoir) of Salmonella typhi. Typhoid Fever and Salmonellosis. Salmonella enterica serovars. Infect domestic animals Eggs and contaminated meat
Infectious Diseases of the Digestive System
Flat worms and Round worms
Phylum Platyhelminthes = Flat worms
Class Cestoda = Tape worms
Scolex contained in egg
holdfast structure with hooks and suckers
Proglottids major body of tapeworm
contains both ovaries and testes = hermaphroditic
Eggs can penetrate intestine of host and form hydatid cysts in tissues
FIGURE 13-57Taenia solium scolex (X64). The Taenia solium scolex has two rings of hooks and four suckers.
Human phase of this worm begins with a filaform larvae penetrating the skin, enters circulation, carried to the lungs, coughed up and swallowed, develops to adulthood in small intestine. Adult worms lay between 10,000 and 20,000 eggs per day. Daily blood loss 0.2ml/adult/day. Microcytic hypochromic anemia develops.
FIGURE 13-68Trichinella spiralis larva in skeletal muscle (W.M., X260). The spiral juvenile and its nurse cell are visible in this preparation.
Eggs are ingested mainly fecal-oral.Egg laden dust can be inhaled. Autoinfection occurs frequently. “Scotch Tape Test” from perianal folds of diagnostic value.