Eucestoda the "broad tapeworm" or "fish tapeworm") and related species. Humans become infected by eating raw, undercooked, or marinated fish acting as a second intermediate or paratenic host harboring metacestodes or plerocercoid larvae. Clinical symptoms are due to the large size of the tapeworm, which often reaches a length exceeding 15 m. The most common symptom is pernicious anemia, caused by the absorption of vitamin B12 by the worm. Other symptoms include various intestinal issues, slight leukocytosis, and eosinophilia. This condition is caused by the plerocercoid larvae of the tapeworm "Spirometra". Humans become infected by drinking contaminated water, eating raw or
Crab-eating macaque in "M. fascicularis", can also infect humans. A few cases have been documented in humans, but for how long humans have been getting infections of this malarial strain is unknown. It is, therefore, not possible to assess if this is a newly emerging health threat, or if just newly discovered due to improved malarial detection techniques. Given the long history of humans and macaques living together in Southeast Asia, it is likely the latter. The use of crab-eating macaques and other nonhuman primates in experimentation is controversial with critics charging that the experiments are cruel, unnecessary and lead to dubious