duodenalis has been sub-classified into eight genetic assemblages (designated A–H). Genotyping of G. duodenalis isolated from various hosts has shown that assemblages A and B infect the largest range of host species, and appear to be the main and possibly only G. duodenalis assemblages that infect humans. Risk factors
According to the United States Centers for Disease Control and Prevention (CDC), people at greatest risk of infection are:

People in childcare settings
People who are in close contact with someone who has the disease
Travelers within areas that have poor sanitation
People who have contact with feces during sexual activity
Backpackers or campers who drink untreated water from springs, lakes, or rivers
Swimmers who swallow water from swimming pools, hot tubs, interactive fountains, or untreated recreational water from springs, lakes, or rivers
People who get their household water from a shallow well
People with weakened immune systems
People who have contact with infected animals or animal environments contaminated with fecesFactors that increase infection risk for people from developed countries include changing diapers, consuming raw food, owning a dog, and travelling in the developing world. However, 75% of infections in the United Kingdom are acquired in the UK, not through travel elsewhere. In the United States, giardiasis occurs more often in summer, which is believed to be due to a greater amount of time spent on outdoor activities and traveling in the wilderness. Transmission
Giardiasis is transmitted via the fecal-oral route with the ingestion of cysts. Primary routes are personal contact and contaminated water and food.
Cheyletiella is a genus of mites that live on the skin surface of dogs, cats, and rabbits.The adult mites are about 0.385 millimeters long, have eight legs with combs instead of claws, and have palpi that end in prominent hooks. They do not burrow into the skin, but live in the keratin level. Their entire 21-day life cycle is on one host. They cannot survive off the host for more than 10 days. Cheyletiellosis
Cheyletiellosis (also known as Cheyletiella dermatitis)," is a mild dermatitis caused by mites of the genus Cheyletiella. It is also known as walking dandruff due to skin scales being carried by the mites. Cheyletiellosis is seen more commonly in areas where fleas are less prevalent, because of the decreased use of flea products that are also efficacious for the treatment of this mite.Cheyletiellosis is highly contagious. Transmission is by direct contact with an affected animal. Presentation
Symptoms in animals vary from no signs to intense itching, scales on the skin, and hair loss. The lesions are usually on the back of the animal. Symptoms in humans include multiple red, itchy bumps on the arms, trunk, and buttocks. Because humans are not a host for the mite, the symptoms usually go away in about three weeks. Though the medical community does not consider a human mite infestation a legitimate diagnosis, it will treat the symptoms if necessary. Diagnosis
Diagnosis is by finding the mites or eggs microscopically in a skin scraping, combing, or on acetate tape applied to the skin.