Published by Australian Academy of Science
Glossary | Hydatids – when a dog is not man's best friend

definitive host and intermediate host. Some parasites have two hosts in their life cycle. The host in which a parasite reaches sexual maturity and reproduces is called the definitive host. The other host is called the intermediate host. In the case of the hydatid tapeworm, dogs are the usual definitive hosts and sheep are the usual intermediate hosts.

larva (plural, larvae). The immature stage of an animal. The larva does not have the same structure as the adult form. For example, tadpoles are frog larvae and caterpillars are butterfly larvae.

parasite. A parasite is an organism that lives on or in another living organism (the host) and gains some advantage at the host's expense.

protoscoleces. Tapeworm larvae. The scolex (plural, scoleces) is the headlike part of the tapeworm, with hooks and suckers that the animal uses to attach to the tissues of its host.

recombinant DNA. Genetically engineered DNA that is prepared in a laboratory by cutting up DNA molecules and splicing together specific DNA fragments. Usually the DNA that is combined is from more than one species. The spliced DNA can then be used to synthesise proteins. More information can be found at Speaking the language of recombinant DNA (Access Excellence, USA).