Morphological plasticity varies with duration of infection: evidence from lactating and virgin wild-derived house mice (Mus musculus) infected with an intestinal parasite (Heligmosomoides polygyrus;Nematoda)

Abstract

With chronic parasite infection, host response to the parasite may change throughout the duration of the infection as the host progresses from the acute to the chronic phase. We investigated the effects of parasite infection ranging in duration from 30 to 120·days on host morphology both alone and in combination with lactation by using captive wild-derived house mice (Mus musculus) experimentally infected with a naturally occurring intestinal nematode (Heligmosomoides polygyrus). We found that some changes in host morphology were greatest at 30-60·days post-infection (e.g. spleen mass) followed by a decline towards the control state whereas other morphological changes were greatest at 90-120·days postinfection (e.g. small intestine mass) after a relatively steady increase with infection duration. For all infection durations, the morphological responses to parasite infection were similar for virgin and lactating mice (except for lean body mass). After accounting for changes in body mass with lactation, lactating mice increased organs of the gastrointestinal tract as well as liver and kidney but had less body fat than virgin mice. This is the first study to demonstrate that morphological plasticity of mice parasitized by H. polygyrus varies with infection duration and that this variation is generally similar for lactating and virgin mice.

Energetic Benefits of Sociality Offset the Costs of Parasitism in a Cooperative Mammal

“…However, such immune responses are usually triggered during the initial parasite invasion and it is during this acute infestation when most experimental studies attempt to measure such costs. As the cestodes in our study were fully matured in the naturally infected study animals, they had presumably reached the chronic phase when hosts usually have already made physiological adjustments to maintain homeostasis [39], [40]. Moreover, it is well established that mature helminth parasites can down-regulate their host's immune system [41], [42] which in this case may account for the reduction in RMR in hosts with low cestode abundance.…”

Strong immune function: a benefit promoting the evolution of sociality?

“…It has been suggested by some authors that spleen size correlates with helminth loads (Kristan & Hammond, 2004;Schwanz, 2006). However, helminth prevalence was low (about 30%) and we could not find a relationship between helminth infection and spleen mass (H. Lutermann, unpubl.…”

Calling Behavior and Parasite Intensity in Treefrogs,Hypsiboas prasinus

“…Parasite infection is often associated with an imbalance of energy and nutrients, as costs are increased by mounting an immune response to infection, repairing tissue damage, and replacing nutrients used by parasites (Lochmiller and Deerenberg, 2000;Tinsley et al, 2002;Kristan and Hammond, 2004). Energy input can be decreased by parasite-induced anorexia and reduced efficiency of nutrient assimilation (Holmes and Zohar, 1990;Kyriazakis et al, 1998;Kristan, 2002).…”