Ive seen a number of posts dealing with diseases found in furbearers. Mange is often the topic of these threads and all too often is misunderstood. Now Ole RdFx has touched on the basics and Ill try to elaborate a bit in the hopes of clarifying things for those interested.
Mange is a parasitic disease caused by an infestation with mites. Mites are Arachnids (spider like) which live IN the skin. The distinction between an infestation and infection is important in the natural history of the mite and disease (Ill get to this point in a minute).
Mites have a rather specific host range. This means that mites can complete their life cycles only in certain animals
fox mites in fox, coyote mites in coyotes and at least some domestic dogs, etc. etc. For the clinical condition know as mange to occur the mites, must be able to complete their cycle in the host upon which they are living. Think of this as a self perpetuating community...a few mites too millions.
Mites can survive and complete portions of their life cycles in / on "non-primary" hosts. In this state, minor kinds of skin lesions appear, mange does not develop and the infestation is self limiting. However these secondary hosts can serve as a reservoir for the mites and thereby provide a link between primary host animals (a rat may harbor the mite for coyotes and transmit the mite to the coyote that, for example, dines on said rat).
Normal man (healthy immuno-competent individuals) are non-primary hosts for mites and therefore do not develop mange or any sort of severe disorder
the infestation is self limiting.
Because mites do not invade deep tissues (cause an infestation) as bacteria, viruses and fungi do (infectious agents) they do not fall prey to the acquired immune defense mechanisms of the host, at least in the same ways infectious agents do. This feature is why, in primary hosts, mange is most often fatal
the primary host has no effective defense. Likewise, non-primary hosts are, by definition, immune to the fatal effects of an uninhibited infestation. It is unclear what specific mechanisms are involved in the immunity observed in non-primary hosts. However, it is clear that an intact immune response is, or can be involved since in immuno-compromised humans (AIDS patients) mite infestations can be fatal.
Mites, being obligate parasites and exothermic (cold blooded), die rapidly in the absence of the warmth and nutritional sources provided by a living host. Once the corps cools the mites die rapidly and the rate of death of the mite increases with decreasing ambient temperatures. Sooooo, if you get a mangy critter, once dead and cold the mites too are dead. Also, you MAY get infested with mites during handling of such an animal but the extent of the infestation will be minor, and limited to skin lesions that will go away on their own in all but those that have a compromised immune defense mechanism.
Hope this helps some.
