Studies on Spirometra theileri (Baer, 1925) n. comb. 2. Pathology of experimental plerocercoid infections.

The pathology associated with the early migratory phase of infection by the sparganum larvae of Spirometra theileri (Baer, 1925) Opuni and Muller, 1974 (Pseudophyllidea:Diphyllobothriidae), has been investigated in TO strain mice and in rhesus monkeys (Macaca mulatta). All infected mice developed haemorrhagic skin lesions and oedema of the joints and often ascites and peritonitis 3-6 weeks after infection. There was a 25% mortality in mice given plerocercoids orally, 37.5% in those injected with procercoids intraperitoneally. From eight weeks after infection larvae in both mice and monkeys were at various stages of encapsulation. One monkey which died three weeks after oral infection with 100 procercoids had developed ascites, haemorrhagic lesions and an acute peritonitis; infarcts were observed in the liver, lungs and spleen. In plerocercoid infections, scolices migrated directly through the duodenal wall within 45 minutes of oral infection in mice and 2 hours in monkeys, causing a minimum of damage apart from small haemorrhagic patches at the sites of penetration. In monkeys an eosinopoenia occurred 7 days after infection (a mean drop from 300 to 150 cells per cu mm), followed by a sudden rise (maximum of 1450 cells per cu mm) lasting from the 3rd to the 7th week. The histopathology and immunopathology associated with the various phases of infection were investigated in both mice and monkeys.