Host-pathogen dynamics of squirrelpox virus infection in red squirrels (Sciurus vulgaris)

The carcases of two wild red squirrels (Sciurus vulgaris) from Anglesey, North Wales, which had severe skin lesions, were presented to the Animal and Plant Health Agency. One was found dead in December 2017 and the second was found moribund in January 2018 but died 2 hours later. Both were examined at postmortem. The affected skin consisted of raised, firm, crusty lesions with pale subcutaneous necrotic tissue over the head particularly the face, eyelids and forehead. In addition, one had similar lesions on the scrotal and perineal area and along one hind leg extending to the foot. Postmortem examination, bacteriology and histopathology confirmed the presence of disease due to Dermatophilus congolensis with typical gross and pathological lesions. Squirrelpox virus was not detected. Here, we report the first description of dermatophilosis in European red squirrels, another important differential diagnosis of skin disease in a nationally declining population.

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Epidemics of squirrelpox virus disease in red squirrels (Sciurus vulgaris): temporal and serological findings

Epidemiology and Infection ◽

10.1017/s0950268808000836 ◽

2008 ◽

Vol 137 (2) ◽

pp. 257-265 ◽

Cited By ~ 23

Author(s):

B. CARROLL ◽

P. RUSSELL ◽

J. GURNELL ◽

P. NETTLETON ◽

A. W. SAINSBURY

Keyword(s):

United Kingdom ◽

Captive Breeding ◽

Virus Disease ◽

Experimental Investigations ◽

Sciurus Vulgaris ◽

Free Living ◽

Red Squirrels ◽

Wild Mammals ◽

The United Kingdom ◽

Squirrelpox Virus

SUMMARYSquirrelpox virus (SQPV) causes a fatal disease in free-living red squirrels (Sciurus vulgaris) which has contributed to their decline in the United Kingdom. Given the difficulty of carrying out and funding experimental investigations on free-living wild mammals, data collected from closely monitored natural outbreaks of disease is crucial to our understanding of disease epidemiology. A conservation programme was initiated in the 1990s to bolster the population of red squirrels in the coniferous woodland of Thetford Chase, East Anglia. In 1996, 24 red squirrels were reintroduced to Thetford from Northumberland and Cumbria, while in 1999 a captive breeding and release programme commenced, but in both years the success of the projects was hampered by an outbreak of SQPV disease in which seven and four red squirrels died respectively. Valuable information on the host–pathogen dynamics of SQPV disease was gathered by telemetric and mark–recapture monitoring of the red squirrels. SQPV disease characteristics were comparable to other virulent poxviral infections: the incubation period was <15 days; the course of the disease an average of 10 days and younger animals were significantly more susceptible to disease. SQPV disease places the conservation of the red squirrel in jeopardy in the United Kingdom unless practical disease control methods can be identified.

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Hepatozoon in Eurasian red squirrels Sciurus vulgaris, its taxonomic identity, and phylogenetic placement

Parasitology Research ◽

10.1007/s00436-021-07229-1 ◽

2021 ◽

Author(s):

David Modrý ◽

Lada Hofmannová ◽

Petr Papežík ◽

Karolina Majerová ◽

Jan Votýpka ◽

...

Keyword(s):

Sciurus Vulgaris ◽

Red Squirrels ◽

Phylogenetic Placement

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Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity

BMC Biology ◽

10.1186/s12915-021-01049-6 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Basabi Bagchi ◽

Quentin Corbel ◽

Imroze Khan ◽

Ellen Payne ◽

Devshuvam Banerji ◽

...

Keyword(s):

Sex Differences ◽

Sexual Dimorphism ◽

Mating System ◽

Sexual Conflict ◽

Experimental Evolution ◽

Parasitic Infections ◽

Pathogen Dynamics ◽

Trade Offs ◽

Host Pathogen ◽

Seed Beetles

Abstract Background Sexual dimorphism in immunity is believed to reflect sex differences in reproductive strategies and trade-offs between competing life history demands. Sexual selection can have major effects on mating rates and sex-specific costs of mating and may thereby influence sex differences in immunity as well as associated host–pathogen dynamics. Yet, experimental evidence linking the mating system to evolved sexual dimorphism in immunity are scarce and the direct effects of mating rate on immunity are not well established. Here, we use transcriptomic analyses, experimental evolution and phylogenetic comparative methods to study the association between the mating system and sexual dimorphism in immunity in seed beetles, where mating causes internal injuries in females. Results We demonstrate that female phenoloxidase (PO) activity, involved in wound healing and defence against parasitic infections, is elevated relative to males. This difference is accompanied by concomitant sex differences in the expression of genes in the prophenoloxidase activating cascade. We document substantial phenotypic plasticity in female PO activity in response to mating and show that experimental evolution under enforced monogamy (resulting in low remating rates and reduced sexual conflict relative to natural polygamy) rapidly decreases female (but not male) PO activity. Moreover, monogamous females had evolved increased tolerance to bacterial infection unrelated to mating, implying that female responses to costly mating may trade off with other aspects of immune defence, an hypothesis which broadly accords with the documented sex differences in gene expression. Finally, female (but not male) PO activity shows correlated evolution with the perceived harmfulness of male genitalia across 12 species of seed beetles, suggesting that sexual conflict has a significant influence on sexual dimorphisms in immunity in this group of insects. Conclusions Our study provides insights into the links between sexual conflict and sexual dimorphism in immunity and suggests that selection pressures moulded by mating interactions can lead to a sex-specific mosaic of immune responses with important implications for host–pathogen dynamics in sexually reproducing organisms.

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