Search results for "intermediate host"

Intestinal Trematode Infections

2014

Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse in regard to their morphology, geographical distribution and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved tran…

An optimised multi-host trematode life cycle: fishery discards enhance trophic parasite transmission to scavenging birds

2016

Overlapping distributions of hosts and parasites are critical for successful completion of multi-host parasite life cycles and even small environmental changes can impact on the parasite's presence in a host or habitat. The generalist Cardiocephaloides longicollis was used as a model for multi-host trematode life cycles in marine habitats. This parasite was studied to quantify parasite dispersion and transmission dynamics, effects of biological changes and anthropogenic impacts on life cycle completion. We compiled the largest host dataset to date, by analysing 3351 molluscs (24 species), 2108 fish (25 species) and 154 birds (17 species) and analysed the resultant data based on a number of …

Intraspecific conflict over host manipulation between different larval stages of an acanthocephalan parasite

2010

Competitive interactions between coinfecting parasites are expected to be strong when they affect transmission success. When transmission is enhanced by altering host behaviour, intraspecific conflict can lead to ‘coinfection exclusion’ by the first-in parasite or to a ‘sabotage’ of behavioural manipulation by the youngest noninfective parasite. We tested these hypotheses in the acanthocephalan parasite Pomphorhynchus laevis, reversing phototaxis in its intermediate host Gammarus pulex. No evidence was found for coinfection exclusion in gammarids sequentially exposed to infection. Behavioural manipulation was slightly weakened but not cancelled in gammarids infected with mixed larval stages…

Proximate factors affecting the larval life history of Acanthocephalus lucii (Acanthocephala).

2007

The growth and eventual size of larval helminths in their intermediate hosts presumably has a variety of fitness consequences. Therefore, elucidating the proximate factors affecting parasite development within intermediate hosts should provide insight into the evolution of parasite life histories. An experimental infection that resulted in heavy intensities of an acanthocephalan (Acanthocephalus lucii) in its isopod intermediate host (Asellus aquaticus) permitted the examination of parasite developmental responses to variable levels of resource availability and intraspecific competition. Isopods were infected by exposure to egg-containing fish feces, and larval infrapopulations were monitor…

The natural history of Echinorhynchus bothniensis Zdzitowiecki and Valtonen, 1987 (Acanthocephala) in a high Arctic lake

2015

The acanthocephalan Echinorhynchus bothniensis Zdzitowiecki and Valtonen, 1987 differs from most other species in the genus Echinorhynchus Zoega in Müller, 1776 by infecting mysids (order Mysida) instead of amphipods (order Amphipoda) as intermediate hosts. Here we report on the occurrence of E. bothniensis in mysids (Mysis segerstralei Audzijonytė et Väinölä) and in its fish definitive hosts in a high Arctic lake. Out of 15907 sampled mysids, 4.8% were infected with a mean intensity of 1.05 worms (range 1–5), although there was notable variation between samples taken in different years and sites. Larger mysids appear more likely to be infected. Of five fish species sampled, charr,Salvelinu…

Carotenoid-based colour of acanthocephalan cystacanths plays no role in host manipulation.

2009

Manipulation by parasites is a catchy concept that has been applied to a large range of phenotypic alterations brought about by parasites in their hosts. It has, for instance, been suggested that the carotenoid-based colour of acanthocephalan cystacanths is adaptive through increasing the conspicuousness of infected intermediate hosts and, hence, their vulnerability to appropriate final hosts such as fish predators. We revisited the evidence in favour of adaptive coloration of acanthocephalan parasites in relation to increased trophic transmission using the crustacean amphipodGammarus pulexand two species of acanthocephalans,Pomphorhynchus laevisandPolymorphus minutus. Both species show car…

Ant Societies Buffer Individual-Level Effects of Parasite Infections

2012

Parasites decrease host fitness and can induce changes in host behavior, morphology, and physiology. When parasites exploit social insects, they influence not only infected individuals but also the society as a whole. Workers of the ant Temnothorax nylanderi are an intermediate host for the cestode Anomotaenia brevis. We studied a heavily parasitized population and found that, although parasite infection had strong and diverse consequences for individual workers, colony fitness remained unchanged. At the individual level, we uncovered differences among the three worker types, infected and healthy workers from parasitized colonies and healthy workers from nonparasitized colonies. Infected wo…

Parasite-induced alteration of plastic response to predation threat: increased refuge use but lower food intake in Gammarus pulex infected with the a…

2014

6 pages; International audience; Larvae of many trophically-transmitted parasites alter the behaviour of their intermediate host in ways that increase their probability of transmission to the next host in their life cycle. Before reaching a stage that is infective to the next host, parasite larvae may develop through several larval stages in the intermediate host that are not infective to the definitive host. Early predation at these stages results in parasite death, and it has recently been shown that non-infective larvae of some helminths decrease such risk by enhancing the anti-predator defences of the host, including decreased activity and increased sheltering. However, these behavioura…

Parasite-induced suppression of aggregation under predation risk in a freshwater amphipod

2012

a b s t r a c t Recent findings suggest that grouping with conspecifics is part of the behavioural defences developed by amphipod crustaceans to face predation risk by fish. Amphipods commonly serve as intermediate hosts for trophically transmitted parasites. These parasites are known for their ability to alter intermediate host phenotype in a way that promotes predation by definitive hosts, where they reproduce. If aggregation in amphipods dilutes the risk to be preyed on by fish, then it may dilute the probability of transmission for the parasite using fish as definitive hosts. Using experimental infections, we tested whether infection with the fish acanthocephalan Pomphorhynchus laevis a…

2021

Social insects are hosts of diverse parasites, but the influence of these parasites on phenotypic host traits is not yet well understood. Here, we tracked the survival of tapeworm-infected ant workers, their uninfected nest-mates and of ants from unparasitized colonies. Our multi-year study on the ant Temnothorax nylanderi, the intermediate host of the tapeworm Anomotaenia brevis, revealed a prolonged lifespan of infected workers compared with their uninfected peers. Intriguingly, their survival over 3 years did not differ from those of (uninfected) queens, whose lifespan can reach two decades. By contrast, uninfected workers from parasitized colonies suffered from increased mortality comp…