Sarcoptes scabiei infestation does not alter the stability of ectoparasite communities

Background

The host represents a heterogeneous ecosystem where multiple parasite species co-occur and interact with each other for space and resources. Although these interactions may rule the features of an infracommunity and may shape the infracommunity response to external perturbations, the resilience of ectoparasite communities to new infestations remains poorly explored.

Methods

We analysed the composition of the ectoparasite communities found on 214 individual Iberian ibexes (Capra pyrenaica) inhabiting the Sierra Nevada Natural Space, southern Spain. Using classification and regression trees, we explored how the presence of Sarcoptes scabiei (a highly contagious mite), the off-host environment and the host sex govern the prevalence and abundance of lice and ticks. Null model analysis was applied to assess the impact of S. scabiei on the structure of the ectoparasite communities.

Results

Our results suggest that S. scabiei infestation acts in tandem with off-host environment and host sex to define the prevalence and abundance of lice and ticks. We also provided evidence for differences in species co-occurrence only at the early stages of S. scabiei infestation. Regarding species diversity, we recorded that ectoparasite communities in scabietic ibexes reached a high richness faster than those in healthy individuals.

Conclusions

Even though we show that ectoparasite burden is correlated with S. scabiei infestation, off-host environment and host sex, the species response to S. scabiei infestation and climate seem to be highly variable and influenced by ectoparasite life-history traits. Ectoparasite communities also appear resilient to perturbations which is in agreement with what was previously reported for endoparasites. Future refinement of sample collection and the incorporation of ecological and epidemiological-related variables may allow us to establish causal effects and deepen the knowledge about the mechanisms and consequences of ectoparasite interactions.

Serum protein response and renal failure in canine Babesia annae infection

Babesia annae piroplasms have recently been recognised as a cause of infection and disease among dogs in Europe. The pathogenesis and clinical implications of this emerging disease remain poorly understood. We conducted this study to describe the electrophoretic profiles associated with the infection and to determine if B. annae associated azotaemia is caused by renal failure. We examined by microscopy 2,979 canine blood samples submitted to a diagnostic laboratory in NW Spain between September 2001 and April 2002. Small ring-shaped piroplasms were detected in blood smears of 87 samples and the identity of 58 of these presumptive cases were confirmed by PCR. This group of 58 infected dogs and a reference group of 15 healthy non-infected dogs were our study population. For all the dogs, serum protein response to -albumin, alpha-1 globulin, alpha-2 globulin, beta globulin and gamma globulin- was measured by capillary electrophoresis. The response of infected and non-infected dogs was compared and within infected dogs, the response of those with azotaemia (19) was compared with that of non-azotaemic dogs (39). Infected dogs presented a significant elevation of total proteins and all the different globulin fractions, and significantly lower levels of albumin compared to non-infected dogs. Among infected dogs, those presenting azotaemia had significantly lower concentrations of total proteins, albumin, beta and gamma globulins, and significantly higher values of alpha-2 globulin. Specific gravity was below the threshold of 1,025 for all dogs with azotaemia for which a urine sample was available (7) suggesting that azotaemia, in these dogs was of renal origin. Azotaemic dogs had higher concentrations of cholesterol and triglycerides, probably as a result of a liver compensatory response to the loss of proteins. We conclude that serum protein response in B. annae infected dogs corresponds to the pattern of a haemolytic syndrome with intense inflammatory reaction and that the azotaemia associated to the infection is very likely of renal origin.