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Home / Case studies / #05
Case study #05
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We are in a regional hunting reserve, with an area of 300 km2, located in the Cantabrian Mountains... where for approximately 4 years the rangers of the area and some hunters have told us that they have sporadically detected deer with alopecia, especially in the head and neck area, or more localized in the abdomen in others, although some had generalized hair loss and poor body condition. To be precise from a clinical point of view, the signs that could be observed ranged from a very localized alopecia in some individuals with some local inflammation, to generalized alopecia with marked hyperkeratosis, presence of scabs, as well as emaciation or cachexia, generalized lymphadenitis, among others. Some of the affected specimens were found dead or were selectively killed for ethical reasons. The detection of cases in deer throughout this period has been about 5 to 16 per year in that area, whose average deer densities are high, estimated at about 10 animals per km2.
Additionally, after coordinating health surveillance with the human medicine services of the region, a suspected case of this disease was reported in a person who indicated that he stopped the car next to a ditch where a dying deer was found and He touched it before calling the authorities. This person has crusty, very itchy papules that have spread to the arms and hands.
News explaining similar situation.
Figure 1: Skin lessions in a deer (source: Christian Gortázar)
Figure 2: Skin lessions in a deer (source: Christian Gortázar)
Figure 3: Skin lessions in a deer (source: Christian Gortázar)
Figure 4: Skin lessions on a person's hand
(source: Miriam Suárez, El Comercio)
Five years ago, an outbreak of a contagious disease, whose main clinical manifestation is skin, began in chamois in the same area, with around 750 animals affected or found dead since then. The affected cervids were mostly adult males, although not exclusively. Some specific cases of roe deer have also been reported in the area.
Figure 5: Affected chamois (source: Christian Gortázar)
From the animals that underwent thorough inspection in the necropsy room, 5 cm x 5 cm skin samples were taken from the edges of the lesion, including healthy and altered tissue, processed in a 10% KOH solution for 60 minutes at 37 °C for the identification of possible parasites under the light microscope, other portions of skin were fixed in 10% buffered formalin for subsequent histopathological analysis.
Under the optical microscope, the following parasitic form was observed (shown in image 6).
After the histopathological study, hyperkeratosis and tunnels with parasites were observed in the stratum corneum of the epidermis, as well as an inflammatory infiltrate (images 7 to 9).
Figure 6: Parasite seen under the optical microscope
(source: Christian Gortázar)
Figure 7: Severe hyperkeratosis and presence of parasitic forms.
(source: Ana Balseiro, Oleaga et al. 2012; https://doi.org/10.1007/s10344-012-0662-y)
Figure 8: Inflammatory infiltrate made up of macrophages, lymphocytes and eosinophils.
(source: Ana Balseiro, Oleaga et al. 2012; https://doi.org/10.1007/s10344-012-0662-y)
Figure 9: Parasites in the stratum corneum with intense immunolabeling
(source: Ana Balseiro, Oleaga et al. 2012; https://doi.org/10.1007/s10344-012-0662-y)
Secondary questions
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Main question
What etiological agent could it be?
- Microsporum spp. (dermatophytosis).
- Poxvirus del ciervo.
- Dermatophilus congolensis (dermatophilosis).
- Sarcoptes scabiei (sarna sarcóptica).
- Demodex spp. (demodicosis).
Solution
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The etiological agent causing the outbreak is the sarcoptic mange mite (Sarcoptes scabiei), which is an obligate ectoparasite with a wide range of mammalian hosts (multi-host parasite), including humans, and highly contagious by direct and indirect contact. Parasitization by this mite is manifested by skin inflammation, itching and skin hypersensitivity, causing excoriation, exudation and even hemorrhagic damage to the skin. As a consequence of the physiological alterations it causes, affected individuals become dehydrated and can die in the most advanced cases.
It is an important disease due to the economic repercussions of its treatment and prophylaxis in domestic livestock, and due to the implications it has on public health as it is a zoonosis. In wildlife, it can pose a serious danger to the population dynamics of certain species, such as the chamois (Rupicapra rupicapra) and the ibex (Capra pyrenaica), species also more frequently affected in the Iberian Peninsula.
Regarding red deer (Cervus elaphus) scabies in Europe, only sporadic cases or small outbreaks have been reported, not posing a risk to the population dynamics of this species, since the impact of the disease is more moderate and sustained. over a period of time, with a pattern similar to that of an enzootic disease, with small spikes, unlike what happens, for example, in the chamois, where the appearance of cases tends to increase and with a greater impact on the population, as shown by Oleaga et al. (2008) in relation to an outbreak of sarcoptic mange in Asturias (doi:10.1016/j.vetpar.2008.03.002), illustrated in image 10.
Action against the epidemiological situation:
The population density of cervids should be reduced, as well as selective hunting of visibly affected individuals and removal from the field. Integrated health surveillance of the wildlife in the area must also be carried out, monitoring the populations of the different species and carrying out serological analyzes that allow assessing the evolution in the maintenance of the infection in the population, as well as establishing clear surveillance protocols. active and passive of this and other diseases.
Actions aimed at raising awareness among the rural population and adequately training guards and environmental agents to prevent transmission to people are relevant.
Figure 10: Number of sarcoptic mange cases in chamois and red deer
and affected surface (in km2) in Asturias from 1995 to 2007.
(Source: Oleaga et al. 2008; doi:10.1016/j.vetpar.2008.03.002)
