We developed a mathematical model to investigate the role of indirect transmission in the spread of infectious diseases, using the illustrative example of sarcoptic mange as a case study. This ...disease can be transmitted through direct contact between an infected host and a susceptible one, or indirectly when potential hosts encounter infectious mites and larvae deposited in the environment, commonly referred to as fomites. Our focus is on exploring the potential of these infectious reservoirs as triggers for emerging infection events and as stable reservoirs of the disease. To achieve this, our mean field compartmental model incorporates the epidemiological dynamics driven by indirect transmission via fomites. We identify different types of dynamics that the system can go into, controlled by different levels of direct and indirect transmission. Among these, we find a new regime where the disease can emerge and persist over time solely through fomites, without the necessity for direct transmission. This possibility of the system reveals an evolutionary pathway that could enable the parasite to enhance its fitness beyond host co-evolution. We also define a new threshold based on an effective reproductive number, that enables us to predict the conditions for disease persistence. Our model allows us to assess the potential effectiveness of various disease intervention measures by incorporating a feature observed in real systems. We hope this contributes to a better understanding of infectious disease outbreaks.
•Different forms of disease transmission lead to different outcomes of an outbreak.•Fomites could act as a key factor for the transition into a stable endemic state.•There is a wider range of possible dynamics, even beyond those predicted by R0.•A threshold for the defined parameter RS could determine the disease outcome.
•Model based on TPB and behavioural economics to predict farmers’ adoption intention of sustainable mange control approaches.•Explore how farmers’ salient beliefs about sustainable mange control ...approaches are biased through the principles of behavioural economics.•Subjective norms, attitude and perceived behavioural control are found to predict farmers’ adoption intention.•Beliefs related to the bandwagon bias and availability bias influence adoption intention through TPB determinants.•Beliefs related to the default bias and loss aversion bias influence the determinants TPB, but not adoption intention.
Resistance against macrocyclic lactones is emerging in Psoroptes ovis mites, the cause of psoroptic mange in sheep and cattle. Therefore, sustainable mange control approaches should be implemented to prevent or slow down resistance. To ensure a proper implementation of such approaches, it is crucial to understand the factors that may impede or facilitate adoption of these practices among farmers. A conceptual model that combines insights from the Theory of Planned Behaviour (TPB, Ajzen, 1991) - a theory that predicts human behaviour -, with insights from behavioural economics (Camerer, 2004; Samson, 2016) – a theory that assumes that behavioural biases or reasoning errors are pervasive in decision-making -, was developed to predict farmers’ adoption intention. In particular, this paper examines how behavioural economics can influence farmers’ beliefs related to sustainable mange control and through which pathways these biased beliefs can predict adoption intention.
A cross-sectional survey study amongst 174 Belgian Blue cattle farmers has been conducted and Structural Equation Modelling was used for analyses. In particular, the model shows that farmers’ positive attitudes towards a sustainable mange control method (attitude) and their perceptions of how others evaluate the sustainable control methods (subjective norms) more strongly predict adoption intention than perceived behavioural control. Additionally, the model shows that adoption intention is explained by the bandwagon bias -the belief that other farmers have a positive opinion about the control method-, and availability bias - farmers who have the belief that mange occurs often on their farm – through the determinants of TPB. Although this bandwagon bias influences farmers adoption intention, the rather low presence of availability bias might explain why adoption intention of a sustainable mange control method is limited. Next, retaining to the default treatment (default bias) influences farmers’ belief that they are capable of implementing control methods on their farm (perceived behavioural control), while the belief that implementing a control method is perceived as a cost for their farm rather than being beneficial (loss aversion bias) negatively influences attitude and perceived behavioural control. We further discuss important implications that can incite farmers’ adoption intention.
•The ectoparasiticide treatment is enough to decrease otitis lesion caused by P. ovis.•Vectra 3D® could be used to control infestation by P. ovis in rabbits.•Spontaneous lesions remission can occur ...in otitis caused by P. ovis in rabbits.
The main of this study was to evaluate the efficacy of dinotefuran, pyriproxyfen and permethrin-combination (Vectra 3D-CEVA) in the topical treatment of rabbits naturally infested with P. ovis. Adult New Zealand rabbits (n = 18) with plaques of crust in both ears were divided into three groups (one control and two treated). On day 0, the animals belonging to the treated groups received a single dose of a commercial ectoparasiticide formulation, recommended for use in dogs. The control group (G1) (n = 6) received no treatment, the treated group (G2) (n = 6) received one drop in each ear, and the remaining volume was applied along the back of the animal in the dorsal midline with the commercial formulation. In the other treated group (G3) (n = 6), animals received the same product used in G2, but all the volumes of 0.5 mL were applied only to the back of the animal (dorsal midline). On days 0, +7, +14, +21, +28 and +35, lesion scores and mites per gram (MPG) of each ear scab were evaluated. Statistical analysis was performed using the statistical software Bioestat 5.01. As the Shapiro-Wilk test determined that the data were nonparametrically distributed, the Kruskal–Wallis test was performed, followed by the Student-Newman–Keuls test, to determine the significance levels among the mean values of mite counts per gram of crusts compared to the three experimental groups. The efficacies for remission of lesion scores were 19.87 % on day +7 to 83.44 % on day +35 for G2 and 70.67 % on day +7 to 92.20 % on day +35 for G3. The efficacies obtained by evaluation of MPG were 100 % on day +7 to 99.86 % on day +35 for G2 and from 93.05 % on day +7 to 99.89 on day +35 for G3. The topical administration of the combination of dinotefuran (4.95 %), pyriproxifen (0.44 %) and permethrin (36 %) on the ears and back or only on the back in rabbits was shown to be effective in naturally controlling mite infestations by P. ovis.
Although mortality caused by Sarcoptes scabiei has been reported in European wild rabbit (Oryctolagus cuniculus) and Iberian hare (Lepus granatensis), there is a lack of detailed information ...regarding the exposure of wild lagomorph species to this parasite. Here, we aimed to determine the seroprevalence and potential risk factors associated with S. scabiei exposure in European wild rabbits and Iberian hares in Mediterranean ecosystems of southern Spain. Between 2018/2019 and 2021/2022 hunting seasons, serum samples from 464 wild rabbits and 132 Iberian hares were collected from 100 hunting grounds in Andalusia (southern Spain). Sera were tested using an in-house indirect ELISA to detect specific anti-S. scabiei antibodies based on the immunodominant protein Ssλ20ΔB3. The overall apparent individual seroprevalence was 15.9% (95/596; 95%CI: 13.0–18.9). Antibodies against S. scabiei were detected in 11.6% (54/464; 95%CI: 8.7–14.5) of the European wild rabbits and 31.1% (41/132; 95%CI: 23.2–39.0) of the Iberian hares. Species (Iberian hare), age (adults) and geographical area (western Andalusia) were identified as risk factors potentially associated with S. scabiei exposure using generalized estimating equation analysis. By applying spatial analysis, two significant cluster of high seropositivity were detected in western and central Andalusia, respectively. The seroprevalence values obtained provide evidence of endemic, widespread and heterogeneous exposure to S. scabiei among wild lagomorph populations in Spanish Mediterranean ecosystems. Our findings underscore the importance of implementing integrated surveillance programs for sarcoptic mange in wild lagomorphs as well as in other sympatric species.
•First epidemiological study on S. scabiei in hare species worldwide.•Widespread, endemic and heterogeneous circulation of S. scabiei in wild lagomorphs.•Species, age and geographical area are risk factors associated with S. scabiei exposure.•Integrated surveillance programs on S. scabiei focused on wild lagomorphs and other sympatric species are required.
Sarcoptic mange is a widely distributed disease, with numerous potential hosts among domestic and wild animals. Nowadays it is considered a neglected re-emergent infection in humans. As a difference ...with domestic pigs, and even with several clinical cases reported in some European countries, it seems that Eurasian wild boars (Sus scrofa) have a low susceptibility to clinical mange. However, because of a case of confirmed transmission from Spanish ibex (Capra pyrenaica) to wild boar in the province of Tarragona, we planned a large-scale ELISA survey in the neighboring Valencian Community (SE Spain). We compared 419 wild boar sera from different management systems (fenced vs. open game estates), different ages (piglets, juveniles, and adults), with different behaviour (gregarious females of all ages and male piglets vs. solitary juveniles and adult males), from areas with different wild boar densities, different wild ruminant densities and different sarcoptic mange epidemiologic situations. The whole prevalence of antibodies against sarcoptic mange in the tested wild boars was 10.5%. No significant differences were found when comparing fenced and free ranging wild boars, males and females, gregarious vs. solitary individuals or among different ages. However, wild boar density was a relevant factor. In areas with a hunting bag of <1 wild boar/km2, considered as a low density of suids, the seroprevalence was 2.94%, but rose to 11.52% in high density districts, constituting a significant difference (p = 0.037). Low wild boar populations would act as a protective factor (OR 0.233; p = 0.049) against coming into contact with the mite. The wild ruminant densities or their sarcoptic mange status did not show any effect on wild boars seroprevalence against this disease. These results reinforce the suggested host-taxon Sarcoptes scabiei specificity and the independence of host-species foci.
•Sarcoptes scabiei affects wild and domestic mammals globally.•Evidence suggests an adaptation of the mite to various host taxa.•The potential for contagion among different host groups remains not fully understood.•Inadvertent transmission may occur between wild ruminants and wild boars.•Analyzing diverse wild boar populations in various contexts helps understand the ecology of scabies.
There are many records of the family Sarcoptidae in bats. The species Notoedres (Notoedres) yunkeri has been reported only once, parasitizing a molossid bat in Panama. In the present study, we expand ...the occurrence of the species to Brazil.
The astigmatid mite Psoroptes ovis (Acari: Proroptidae) causes the highly contagious and debilitating ovine disease, sheep scab. This ectoparasitic infection has a high economic and animal welfare ...impact on British sheep farming. Following recent work demonstrating resistance of Psoroptes mites to moxidectin, a widely used macrocyclic lactone (ML) treatment for scab, the current study compared the toxicity of three of the commonly administered macrocylic lactone therapeutic treatments (moxidectin, ivermectin and doramectin) to P. ovis from outbreak populations that had appeared unresponsive to treatment. These outbreak populations were from Wales and south west England. The data presented demonstrate that there is resistance to all three available ML compounds in populations of Psoroptes mites. However, considerable variation in response suggested that resistance alone was not responsible for the reported lack of efficacy in all of the submitted cases; lack of response in others may be associated with inappropriate treatment application or management. These data highlight the importance of the appropriate use of these compounds to manage national scab incidence at levels that are consistent with acceptable animal welfare standards, while attempting to reduce the development and spread of resistance.
Mange, a parasitic skin disease caused by various species of mites, is found in free-ranging wildlife populations and has been increasingly reported in American black bears (Ursus americanus) over ...the last decade in New York State (NYS), USA. Our goal was to describe the geographic, seasonal, and demographic factors associated with mange in this species in NYS. Our retrospective study used historic, opportunistic data from diagnostic necropsy records and visual sighting reports collected by the NYS Wildlife Health Program from 2009 to 2018. We used chi-square tests for independence and odds ratios to examine whether geographic location, year, season, sex, age, and reason for laboratory submission were associated with mange in bears. We used maps and seasonal analysis to investigate emerging patterns. We confirmed increased black bear mange reports in recent years. Necropsy data revealed more bears submitted to the laboratory because of mange, mainly caused by Sarcoptes scabiei; females were more likely than males to present with sarcoptic mange. We found that cases of mange in the Northern Zone were widely disseminated throughout the region, whereas cases in the Southern Zone were concentrated in two areas along the Pennsylvania border. Seasonally, mange cases showed peaks occurring in late spring to early summer and in fall. Our results were on the basis of available data; a comprehensive statewide surveillance program would be useful to better understand the apparent increase in mange and its potential impact on both the welfare of individual animals and the population of black bears in NYS. Additional research on the timing of transmission dynamics associated with females in winter dens may be helpful to wildlife managers to identify strategies to mitigate deleterious spread of the disease in black bears.
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