Yes you are right the most common skin diseases in camelids are manage and ringworm , but now there are many cases which are seem to be due to zn deficiency which showed also what we called it parakeratosis and I couldn't find any article in camel regarding this condition ( just one in Lama and MSC thesis in Iraq).
Is determination the concentration of zn in the blood of suspected camel will be helping to consider the case as zn deficiency when it was negative for mange and ringworm?
Googling "Zn deficiency in camel" give a lot of results !
Determination of Zn blood levels may be useful when meeting a single adult camel in normal body condition showing parakeratosis among healthy camels. If all camels shows parakeratosis you must be absolutely sure that is not a chronic case of mange. It may be necessary to consider that in camels skin conditions is seriously negatively affected by an insufficient "salt" intake. Are you sure that your camels ingest an adequate amount of salt? The presence of salt blocks in the paddock is not a guarantee of appropriate salt ingestion, camels cannot lick and therefore salt need to be provided as a loose granules formulation.
May simply want to try slapping zinc ointment on skin on fiberless or fiber poor areas. Some skin conditions will improve overnight! Won' t do any harm, is cheap and practical.