Walking barefoot on sand or soil is not advisable in many parts of the world (not excluding Florida) because of the risk of infection acquired by contact with contaminated soil, and because of the risk of animal bites and stings, or injuries.
Hookworm infection is found in the tropics and subtropics. Human hookworm larvae are found in the soil in areas of poor sanitation where people have been defecating. The tiny larvae penetrate intact skin, and migrate to the lungs before settling in the gut. Though mainly a disease of farmers working barefoot, visitors to these areas may acquire light, asymptomatic infections. With repeated infections, severe hookworm anaemia can develop.
Strongyloidiasis is a threadworm infection common through warm, wet tropical and subtropical areas: villages and rural areas of South and Central America, Africa and India. Like hookworm, the larvae is excreted in human feces, infection occurs from skin penetration, usually in the feet with migration to the lungs and gut. Unlike hookworm, the larvae are able to mature in the human host to an invasive filariform, invade skin and maintain infection indefinitely. Symptoms include an itchy rash at time of infection, episodic itchy lesions and non-specific gastrointestinal symptoms throughout the time of infection. Disseminated infection is more likely to affect those with weakened immune systems.
Cutaneous Larva Migrans is caused by hookworm larvae from dogs, cats and other animals. Larvae penetrate unbroken skin: a barefoot or bare back walking/lying unprotected on the sand. The infection is limited to the epidermis and typically causes a linear. The disease is not uncommon in tourists, who become infected on beaches in the Americas, Africa, Asia, but most often in the Caribbean.
This is caused by the jigger flea which lives outdoors in the sand in Central and South America and West Africa. The flea burrows into the skin, usually on the feet, under the toenails and between the toes causing inflammation and ulceration. The flea is best removed with a sterilized safety pin, preferably by an expert .
Many wounds causing tetanus occur on the feet or legs. Tetanus is a greater hazard for those going on safari, trekking, climbing or exploring. A bacterial disease marked by rigidity and spasms of the voluntary muscles
Unprotected feet are subject to cuts, scrapes or other breaks in the skin which can lead to infection. Except for diabetics, this is rarely serious, but it is potentially disabling for the traveler with a limited time in a foreign country.