Effects of the clinical severity of disease and concomitant pyoderma on serum acute-phase proteins concentrations in dogs with sarcoptic mange

Adaptive interventions for advancing in situ wildlife disease management

There is a critical need for advancements in disease management strategies for wildlife, but free-living animals pose numerous challenges that can hinder progress. Most disease management attempts involve fixed interventions accompanied by post hoc outcome assessments focused on success or failure. Though these approaches have led to valuable management advances, there are limitations to both the rate of advancement and amount of information that can be gained. As such, strategies that support more rapid progress are required. Sarcoptic mange, caused by epidermal infection with Sarcoptes scabiei mites, is a globally emerging and re-emerging panzootic that exemplifies this problem. The bare-nosed wombat (Vombatus ursinus), a marsupial endemic to southeastern Australia, is impacted by sarcoptic mange throughout its geographic range and enhanced disease management capabilities are needed to improve upon existing in situ methods. We sought to advance in situ wildlife disease management for sarcoptic mange in free-living bare-nosed wombats, implementing an adaptive approach using fluralaner (Bravecto, MSD Animal Health) and a structured process of learning and method-optimisation. By using surveillance of treated wombats to inform real-time management changes, we have demonstrated the efficacy of topically administered fluralaner at 45 and 85 mg/kg against sarcoptic mange. Importantly, we observed variation in the effects of 45 mg/kg doses, but through our adaptive approach found that 85 mg/kg doses consistently reduced mange severity. Through modifying our surveillance program, we also identified individual-level variation in wombat observability and used this to quantify the level of surveillance needed to assess long-term management success. Our adaptive intervention represents the first report of sarcoptic mange management with fluralaner in free-living wildlife and evaluation of its efficacy in situ. This study illustrates how adapting interventions in real time can advance wildlife disease management and may be applicable to accelerating in situ improvements for other host-pathogen systems.

Non-specific markers of inflammation in bare-nosed wombats (Vombatus ursinus) with sarcoptic mange

Sarcoptic mange, caused by epidermal infection with Sarcoptes scabiei, negatively impacts the health, welfare, and local abundance of bare-nosed wombats (Vombatus ursinus) in Australia. Improved understanding of the host immune response to disease and its contribution to pathophysiology could be used to inform management actions for this species in and ex situ. To evaluate the immune response of bare-nosed wombats to sarcoptic mange, we validated three assays (haptoglobin, agarose gel electrophoresis, and micro-erythrocyte sedimentation rate) measuring non-specific markers of inflammation using serum samples from free-living wombats from Tasmania (n = 33). We then analysed correlations between the assay results for each non-specific marker of inflammation and wombat's sarcoptic mange scores, and performed histopathological examinations to investigate association of the acute phase response with systemic amyloidosis. We present evidence that haptoglobin and erythrocyte sedimentation rate increased, and albumin decreased, in association with sarcoptic mange scores. This research demonstrates links between the acute phase response and sarcoptic mange severity in bare-nosed wombats, highlighting the utility of non-specific markers of inflammation for aiding assessment of the systemic effects of mange. Showing the value of agarose gel electrophoresis, we also identified specific acute phase proteins warranting future evaluation and found evidence of an immunoglobulin response in mange-affected wombats, revealed by increasing γ-globulins in association with apparent disease severity. Meanwhile, owing to its relatively low resource requirements and rapidity, the erythrocyte sedimentation rate assay may be useful as a point-of-care test to support therapeutic decisions in the field. Our methods and findings are likely to be applicable to a range of other clinical and population health scenarios in captive and free-living wombats, and species impacted by sarcoptic mange globally.

Demographics and tenure of the Chilean urban dog population. A mathematical model

BACKGROUND

Irresponsible dog ownership in urban areas is a public health concern with significant implications for human, animal, and environmental welfare. Factors such as abandonment, variations in adoption, insufficient supervision, emerging identification initiatives, and collective feeding impact the growth of stray dog populations and the transmission of diseases. Developing a modeling tool to understand the dynamics of canine population growth and the effect of human behavior on this phenomenon is essential.

METHODS

An ordinary differential equation model was developed to depict the growth dynamics and movements of urban dog populations, distinguishing between those with owners (restricted and semi-restricted) and those without (stray and community dogs). Two equilibrium states of the system were analyzed: with and without the presence of individually owned dogs. An increase rate for the population of individually owned dogs was calculated, and a local sensitivity analysis was conducted to assess the impact of parameters on the reduction of this population. Additionally, two global sensitivity analysis methods were used to evaluate the simultaneous influence of the parameters.

RESULTS

Findings indicate that system equilibrium depends on various dog categories. Although total eradication of stray and community dogs is unlikely, equilibrium levels are directly related to subpopulation growth rates, responsible ownership practices, and adoption and abandonment rates. The growth rates of the population of dogs without individual owners have a direct and proportional influence on their regulation, while adoption rates have an inverse and proportional effect. The study, through global sensitivity analysis, identifies key parameters for each dog subpopulation. For restricted dogs, environmental carrying capacity is the most variable factor; for semi-restricted dogs, awareness of responsible ownership is crucial. The abandonment of restricted dogs significantly impacts stray dog dynamics, while the transition from stray to community status is an important variable factor for community dogs.

CONCLUSION

Addressing the situation of unowned dogs requires a collective effort to reduce risks associated with the spread of zoonotic diseases, environmental pollution, and biodiversity loss, thus contributing to public health and environmental conservation.

Crusted scabies in a rabbit model: a severe skin disease or more?

BACKGROUND

Around 200-300 million people are estimated to be affected by scabies annually worldwide. However, the mechanisms by which this disease may affect the general condition of the host are not entirely clear. The aim of the present study was to evaluate the systemic changes that may accompany crusted scabies in both treated and non-treated experimental animals.

METHODS

Male New Zealand rabbits were infected with Sarcoptes scabiei var. cuniculi and divided into the following three groups: control, ivermectin-treated, and fluralaner-treated. Several methods were used to evaluate the systemic changes, including histopathological examination of the liver, kidney, heart, and spleen, as well as the measurement of serum biochemical parameters and immunological parameters.

RESULTS

Several definite structural and functional changes at the systemic level were revealed, as evidenced by the observed histopathological changes in the tissue sections of internal organs and the highly significant increases in markers of systemic inflammation, serum procalcitonin, and oxidative stress markers. Abnormalities in the liver and renal function results, as well as in the serum lipid profile, were also noted. Additionally, a disorganized immune response was noted, evidenced by a mixed type 1 and type 2 helper T cell response. Although there was notable clinical and parasitological cure in the ivermectin-treated group, the histopathological, biochemical, and immunological markers indicated incomplete resolution. In contrast, the fluralaner-treated group exhibited a nearly complete resolution of changes in these parameters.

CONCLUSIONS

We conclude that crusted scabies is a systemic syndrome that can affect several organs besides the skin. Inflammation, oxidative stress, and possibly bacterial infections, are all implicated as underlying mechanisms of tissue damage due to the disease. We recommend that fluralaner, a promising scabicidal agent, should be studied for possible human use, and especially for control programs.