The CDC recommends hand-washing and avoiding potentially contaminated food and untreated water.

Boiling suspect water for one minute is the surest method to make water safe to drink and kill disease-causing microorganisms such as "Giardia lamblia" if in doubt about whether water is infected. Chemical disinfectants or filters may be used.

According to a review of the literature from 2000, there is little evidence linking the drinking of water in the North American wilderness and Giardia. CDC surveillance data (for 2005 and 2006) reports one outbreak (6 cases) of waterborne giardiasis contracted from drinking wilderness river water in Colorado. However, less than 1% of reported giardiasis cases are associated with outbreaks.

Person-to-person transmission accounts for the majority of "Giardia" infections and is usually associated with poor hygiene and sanitation. "Giardia" is found on the surface of the ground, in the soil, in undercooked foods, and in water, and on hands without proper cleaning after handling infected feces. Water-borne transmission is associated with the ingestion of contaminated water. In the U.S., outbreaks typically occur in small water systems using inadequately treated surface water. Venereal transmission happens through fecal-oral contamination. Additionally, diaper changing and inadequate hand washing are risk factors for transmission from infected children. Lastly, food-borne epidemics of "Giardia" have developed through the contamination of food by infected food-handlers.

According to the CDC, "Those at greatest risk are travelers to countries where giardiasis is common, people in child care settings, those who are in close contact with someone who has the disease, people who swallow contaminated drinking water, backpackers or campers who drink untreated water from lakes or rivers, people who have contact with animals who have the disease, and men who have sex with men."

In the United States, giardiasis occurs more often during the summer. This is believed to be due to a greater amount of time spent on outdoor activities and traveling in the wilderness.

Humans are accidental hosts of "Toxocara", yet toxocariasis is seen throughout the world. Most cases of toxocariasis are seen in people under the age of twenty. Seroprevalence is higher in developing countries, but can be considerable in first world countries, as well. In Bali, St. Lucia, Nepal and other countries, seroprevalence is over fifty percent. Previous to 2007, the U.S. seroprevalence was thought to be around 5% in children. However, Won et al. discovered that U.S. seroprevalence is actually 14% for the population at large. In many countries, toxocariasis is considered very rare. Approximately 10,000 clinical cases are seen a year in the U.S., with ten percent being OLM. Permanent vision loss occurs in 700 of these cases.

Young children are at the greatest risk of infection because they play outside and tend to place contaminated objects and dirt in their mouths. Dog ownership is another known risk factor for transmission. There is also a significant correlation between high "Toxocara" antibody titers and epilepsy in children.

Parasitic loads as high as 300 larvae in a single gram of liver have been noted in humans. The “excretory-secretory antigens of larvae… released from their outer epicuticle coat [and]… readily sloughed off when bound by specific antibodies” incite the host’s immune response. The tipping point between development of VLM and OLM is believed to be between 100 and 200 larvae. The lighter infection in OLM is believed to stimulate a lower immune response and allow for migration of a larva into the eye. Larvae are thought to enter the eye through the optic nerve, central retinal artery, short posterior ciliary arteries, soft tissues, or cerebrospinal fluid. Ocular granulomas that form around a larva typically are peripheral in the retina or optic disc.

Visceral larva migrans seems to affect children aged 1–4 more often while ocular larva migrans more frequently affects children aged 7–8. Between 4.6% and 23% of U.S. children have been infected with the dog roundworm egg. This number is much higher in other parts of the world, such as Colombia, where up to 81% of children have been infected.

Actively involving veterinarians and pet owners is important for controlling the transmission of "Toxocara" from pets to humans. A group very actively involved in promoting a reduction of infections in dogs in the United States is the Companion Animal Parasite Council -- CAPC. Since pregnant or lactating dogs and cats and their offspring have the highest, active parasitic load, these animals should be placed on a deworming program. Pet feces should be picked up and disposed of or buried, as they may contain "Toxocara" eggs. Practicing this measure in public areas, such as parks and beaches, is especially essential for decreasing transmission. Up to 20% of soil samples of U.S. playgrounds have found roundworm eggs. Also, sandboxes should be covered when not in use to prevent cats from using them as litter boxes. Hand washing before eating and after playing with pets, as well as after handling dirt will reduce the chances of ingesting "Toxocara" eggs. Washing all fruits and vegetables, keeping pets out of gardens and thoroughly cooking meats can also prevent transmission. Finally, teaching children not to place nonfood items, especially dirt, in their mouths will drastically reduce the chances of infection.

Toxocariasis has been named one of the neglected diseases of U.S. poverty, because of its prevalence in Appalachia, the southern U.S., inner city settings, and minority populations. Unfortunately, there is currently no vaccine available or under development. However, the mitochondrial genomes of both "T. cati" and "T. canis" have recently been sequenced, which could lead to breakthroughs in treatment and prevention.

Mortality rate in treated cases

- 0-2% in treated cases among immunocompetent patients

- 29% in immunocompromised patients

- 40% in the subgroup of patients with AIDS

- 68% in patients presenting as acute respiratory distress syndrome (ARDS)

There are a very small number of cases of human-to-human transmission of "B. dermatitidis" related to dermal contact or sexual transmission of disseminated blastomycosis of the genital tract among spouses.

Protein poisoning (also referred to colloquially as rabbit starvation, mal de caribou, or fat starvation) is a rare form of acute malnutrition thought to be caused by a complete absence of fat in the diet.

Excess protein is sometimes cited as the cause of this issue; when meat and fat are consumed in the correct ratio, such as that found in pemmican (which is 50% fat by volume), the diet is considered nutritionally complete and can support humans for months or more. Other stressors, such as severe cold or a dry environment, may intensify symptoms or decrease time to onset. Symptoms include diarrhea, headache, fatigue, low blood pressure, slow heart rate, and a vague discomfort and hunger (very similar to a food craving) that can be satisfied only by the consumption of fat.

Protein poisoning was first noted as a consequence of eating rabbit meat exclusively, hence the term, "rabbit starvation". Rabbit meat is very lean; commercial rabbit meat has 50–100 g dissectable fat per 2 kg (live weight). Based on a carcass yield of 60%, rabbit meat is around 8.3% fat while beef and pork are 32% fat and lamb 28%.

Given the lack of scientific data on the effects of high-protein diets, the US Food and Nutrition Board does not set a tolerable upper intake level nor upper acceptable macronutrient distribution range for protein.

Familial transmission is now recognized in a small proportion of people with MacTel type 2; however, the nature of any related genetic defect or defects remains elusive. The MacTel genetic study team hopes that exome analysis in the affected population and relatives may be more successful in identifying related variants.

Although a variety of complex classification schemes are described in the literature, there are essentially two forms of macular telangiectasia: type 1 and type 2. Type 1 is typically unilateral and occurs almost exclusively in males after the age of 40.

Type 2 is mostly bilateral, occurs equally in males and females.