© Angel Fernandez Flores, MD, PhD Demodex infection

Demodex infection

 

Aka: Demodicosis

 

Cause

Demodex are mites which are obligatory parasites and many times colonize the skin of mammals without any pathologic consecuence.

 

Pathogenesis

Demodex live for about 14 to 18 days.

If they have the chance to reproduce during that period, the number of the mites in the infected patient will increase.

The mite mainly eats keratinocytes and sebum.

Therefore they are preferently located in sebaceous areas, like the face, forehead, nose and ear.

They cannot survive outside the host, but transmision due to close contact is possible.

Although newborns can be infected due to contact with the mother, for instance, the prevalence of Demodex in children is low, due to the low production of sebum by their skin.

It is controversial if Demodex is per se responsible of some pathology in humans or if it is the inocent withness in the wrong battlefield.

Possible factors related with its pathgenicity are:

Possible pathogenic mechanisms for the disease are:

 

 

Morphology


In humans, there mainly two types of Demodex:

 

 

 

 

Clinical diseases alleged to be related to Demodex infection:

Pityriasis folliculorum:

Acne rosacea

Demodicosis gravis

Seborrheic dermatitis

 

Morphology

Pityriasis folliculorum:

Demodicosis gravis:

 

 

Main differentials

Scabiosis: Mite located in the epidermis. Birrefringent larger spines. External birrefringent scybala.

 

© Angel Fernandez Flores, MD, PhD