"The epithelial layer of the skin provides an essential function as a protective barrier against insult from the outside environment. The major cell type in this layer is keratinocytes which consists around 85% of living epidermal cells. Keratinocytes are the cells of stratified squamous epithelia. It is so named because its most abundant protein is keratin."
"Morgellons disease (MD) is a term that has been used in the last decade to describe filaments that can be found in human epidermis. It is the subject of considerable debate within the medical profession and is often labeled as delusions of parasitosis or dermatitis artefacta. This view is challenged by recent published scientific data put forward between 2011-2013 identifying the filaments found in MD as keratin and collagen based and furthermore associated with spirochetal infection."
The word association is key here, an "association"
A study of genetics would reveal that to get something novel to grow from the skin is a form of Gene Expression, to accomplish that an adjustment of cellular DNA is required.
There are only two bacteria known to Science that can accomplish this and one of them is Agrobacterium, that is why it is used to Genetically-Modified the food supply, the other is Bartonella. Borrelia can not accomplish this as noted in the scientific literature.