Postcyclic transmission and its effect on the distribution of Paulisentis missouriensis (Acanthocephala) in the definitive host
suggesting that ducks are not suitable definitive hosts
for this species.
Consequently, they exhibit higher levels of mortality in these conditions than definitive hosts
. In addition, trematode infection sterilises host snails, and is often associated with greater mortality in infected individuals.
However the lack of Sarcocystis species infection in rock pigeons may be due to absence of definitive host
in this area.
Some of these parasites, in particular, can induce phenotypic changes in their intermediate hosts that are supposed to increase the probability of predation by their definitive hosts
, thus increasing their own probability of transmission (Poulin and Thomas, 1999; Moore, 2002).
Environmental impacts influence the density of intermediate and definitive hosts
, making them more susceptible to infections (Lafferty & Holt 2003) and giving way to an increase in prevalence and even to the pathogenicity of parasites (Holmes 1996).
The causative tapeworm lives in the small intestine of definitive hosts
, such as dogs and other canids , whereas, when transmitted to humans, it can affect various organs, including the liver, lungs, brain, and the urinary tract .
In addition by their use on of Isopods and Amphipods (only in L (L.) propinqua) as second intermediate hosts and Charadriformes and Anseriformes birds, as definitive hosts
. L (L.) cruzi has already been differentiated from L (L.) gavilanicola (see above).
 In lifecycle of Wuchereria bancrofti, man is a definitive host
and culex mosquito is an intermediate host.
Dog is its definitive host
and sheep, pigs, cattle, goats, horses, camels, wallabies, kangaroos and humans are their intermediate hosts.
Dioctophyme renale (Goeze, 1782) is known as giant kidney worm since it is frequently found in the renal pelvis of the definitive host
and can be up to 100 cm long, the largest nematode described in mammals.
Humans are the definitive host
, although certain aquatic snails act as the intermediate host.