Infestation is the state of being invaded or overrun by pests or parasites. It can also refer to the actual organisms living on or within a host.

In general, the term "infestation" refers to parasitic diseases caused by animals such as arthropods (i.e. mites, ticks, and lice) and worms, but excluding conditions caused by protozoa, fungi, bacteria, and viruses, which are called infections.

Due to the high number of hosts, eradication of tungiasis is not feasible, at least not easily so. Public health and prevention strategies should then be done with elimination as the target. Better household hygiene, including having a cemented rather than a sand floor, and washing it often, would lower the rates of tungiasis significantly.

Though vaccines would be useful, due to the ectoparasitic nature of chigoe flea, they are neither a feasible nor an effective tool against tungiasis. Nevertheless, due to the high incidence of secondary infection, those at risk of tungiasis should get vaccinated against tetanus. A better approach is to use repellents that specifically target the chigoe flea. One very successful repellent is called Zanzarin, a derivative of coconut oil, jojoba oil, and aloe vera. In a recent study involving two cohorts, the infestation rates dropped 92% on average for the first one and 90% for the other. Likewise, the intensity of the cohorts dropped by 86% and 87% respectively. The non-toxic nature of Zanzarin, combined with its "remarkable regression of the clinical pathology" make this a tenable public health tool against tungiasis.

The use of pesticide, like DDT, has also led to elimination of the "Tunga penetrans", but this control/prevention strategy should be utilized very carefully, if at all, because of the possible side effects such pesticides can have on the greater biosphere. In the 1950s, there was a worldwide effort to eradicate malaria. As part of that effort, Mexico launched the Campaña Nacional para la Erradicación de Paludismo, or the National Campaign for the Eradication of Malaria. By spraying DDT in homes, the Anopheles a genus of mosquitoes known to carry the deadly Plasmodium falciparum was mostly eliminated. As a consequence of this national campaign, other arthropods were either eliminated or significantly reduced in number, including the reduviid bug responsible for Chagas disease (American Trypanosomiasis) and "T. penetrans". Controlled, in-home spraying of DDT is effective as it gives the home immunity against arthropods while not contaminating the local water supplies and doing as much ecological damage as was once the case when DDT was first introduced.

While other species gradually gained resistance to DDT and other insecticides that were used, "T. penetrans did" not; as a result, the incidence of tungiasis in Mexico is very low when compared to the rest of Latin America, especially Brazil, where rates in poor areas have been known to be as high or higher than 50%. There was a 40-year period with no tungiasis cases in Mexico. It was not until August 1989 that three Mexican patients presented with the disease. Though there were other cases of tungiasis reported thereafter, all were acquired in Africa.

About 14 million people, mainly children, are treated annually for head lice in the United States alone. Only a small proportion of those treated, however, may have objective evidence of an extant infestation. High levels of louse infestations have also been reported from all over the world including Denmark, Sweden, U.K., France and Australia.

Normally head lice infest a new host only by close contact between individuals, making social contacts among children and parent child interactions more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head-to-head contact is by far the most common route of lice transmission.

The United Kingdom's National Health Service, and many American health agencies, report that lice "prefer" clean hair, because it's easier to attach eggs and to cling to the strands.

Head lice ("Pediculus humanus capitis") are not known to be vectors of diseases, unlike body lice ("Pediculus humanus humanus"), which are known vectors of epidemic or louse-borne typhus ("Rickettsia prowazekii"), trench fever ("Rochalimaea quintana") and louse-borne relapsing fever ("Borrelia recurrentis").

For the most part, the chigoe flea lives 2–5 cm below the sand, an observation which helps explains its overall distribution. The temperature is generally too hot for the larvae to develop on the surface of the sand and the deeper sand does not have enough oxygen. This preferred ecological niche offers a way to decrease transmission among humans by investing in concrete grounds as opposed to the sand that is usually used in shacks and some favelas. Indeed, Nany et al. (2007) report that "In shacks with concreted ground being cleaned every day with water, Tunga [penetrans] larvae were hardly found."

In a longitudinal study conducted from March 2001 to January 2002, incidence of tungiasis was found to vary significantly with the local seasons of an endemic community in Brazil. In particular, the study found that "occurrence of tungiasis varies throughout the year and seems to follow local precipitation patterns. Maximum and minimum prevalence rates differed by more than a factor of three." The authors suggest that the correlation is due to the high humidity in the soil impairing larval development during the rainy season, as well as the more obvious reason that rain may simply wash away all stages of "T. penetrans" due its small size of 1mm.

Acting as both biological vectors and definitive hosts, humans have spread "Tunga penetrans" from its isolated existence in the West Indies to all of Latin America and most of Africa via sea travel. Since the chigoe flea technically has no reservoir species and the female will cause tungiasis to any mammalian organism it can penetrate, this means the flea will have a relatively large number of hosts and victims. Epidemiologically, this is important as tungiasis often causes secondary infections.

This condition, is caused by body louse ("Pediculus humanus humanus", sometimes called "Pediculus humanus corporis") is a louse which infests humans and is adapted to lay eggs in clothing, rather than at the base of hairs, and is thus of recent evolutionary origin. Pediculosis is a more serious threat due to possible contagion of diseases such as typhus. Epidemiology and treatment of human body lice is described in the article on body lice.

An ectoparasitic infestation is a parasitic disease caused by organisms that live primarily on the surface of the host.

Examples:

- Scabies

- Crab louse (pubic lice)

- Pediculosis (head lice)

- "Lernaeocera branchialis" (cod worm)

Most of the mites which cause this affliction to humans are from the order Acari, hence the name Acariasis. The entire taxonomic classification to order would be:

- Kingdom: Animalia

- Phylum: Arthropoda

- Subphylum: Chelicerata

- Class: Arachnida

- Order: Acari (At the order level, there is still substantial argument among researchers as to how to categorize Acari. Some call it a subclass, others a superorder, "Acarina".)

Specific species involved include:

- Acariformes

- Trombidiformes

- "Trombicula" species (trombiculosis or chiggers)

- "Demodex" species (Demodicosis)

- "Pyemotes tritici"

- "Cheyletiella"

- Sarcoptiformes

- "Sarcoptes scabiei" (Scabies)

- Parasitiformes

- "Dermanyssus gallinae"

- "Liponyssoides sanguineus"

- "Ornithonyssus bacoti", "Ornithonyssus bursa", "Ornithonyssus sylviarum"

- Another candidate is "Androlaelaps casalis". However, based on this mite's life style as a predator on other mite species (such as the previously-mentioned "Dermanyssus gallinae"), it is highly unlikely to be a cause of acariasis.

Some of these reflect reports existing of human infestation by mites previously believed not to prey on humans.

There are several complications with the terminology:

Acariasis is a term for a rash, caused by mites, sometimes with a papillae (pruritic dermatitis), and usually accompanied by severe itching sensations. An example of such an infection is scabies.

The closely related term, mange, is commonly used with domestic animals (pets) and also livestock and wild mammals, whenever hair-loss is involved. "Sarcoptes" and "Demodex" species are involved in mange, but both of these genera are also involved in human skin diseases (by convention only, not called mange). "Sarcoptes" in humans is especially severe symptomatically, and causes the condition scabies noted above.

Another genus of mite which causing itching but rarely causes hair loss because it burrows only at the keratin level, is "Cheyletiella." Various species of this genus of mite also affect a wide variety of mammals, including humans.

Mite infestation sometimes implies an ectoparasitic, cutaneous condition such as dermatitis. However, it is possible for mites to invade the gastrointestinal and urinary tracts.

MeSH uses the term "Mite Infestations" as pertaining to Acariformes. However, mites not in this grouping can be associated with human disease. (See "Classification", below.)

The term Acari refers to ticks and mites together, which can cause ambiguity. (Mites are a paraphyletic grouping).

Mites can be associated with disease in at least three different ways: (1) cutaneous dermatitis, (2) production of allergin, and (3) as a vector for parasitic diseases. The language used to describe mite infestation often does not distinguish among these.

In laboratory animals, prevention includes a low-stress environment, an adequate amount of nutritional feed, and appropriate sanitation measurements. Because animals likely ingest bacterial spores from contaminated bedding and feed, regular cleaning is a helpful method of prevention. No prevention methods are currently available for wild animal populations.

Currently, antibiotic drugs such as penicillin or tetracycline are the only effective methods for disease treatment. Within wild populations, disease control consists of reducing the amount of bacterial spores present in the environment. This can be done by removing contaminated carcasses and scat.

Prevention is through use of Stock coryza-free birds. In other areas culling of the whole flock is a good means of the disease control. Bacterin also is used at a dose of two to reduce brutality of the disease. Precise exposure has also has been used but it should be done with care. Vaccination of the chicks is done in areas with high disease occurrence. Treatment is done by using antibiotics such as erythromycin, Dihydrostreptomycin, Streptomycin sulphonamides, tylosin and Flouroquinolones .

White band disease (Acroporid white syndrome) is a coral disease that affects acroporid corals and is distinguishable by the white band of dead coral tissue that it forms. The disease completely destroys the coral tissue of Caribbean acroporid corals, specifically elkhorn coral ("Acropora palmata") and staghorn coral ("A. cervicornis"). The disease exhibits a pronounced division between the remaining coral tissue and the exposed coral skeleton. These symptoms are similar to white plague, except that white band disease is only found on acroporid corals, and white plague has not been found on any acroporid corals. It is part of a class of similar disease known as "white syndromes", many of which may be linked to species of "Vibrio" bacteria. While the pathogen for this disease has not been identified, "Vibrio carchariae" may be one of its factors. The degradation of coral tissue usually begins at the base of the coral, working its way up to the branch tips, but it can begin in the middle of a branch.

Some herbaceous hosts naturally have the Cherry X Disease. Once the spreads to the cherry hosts, with the help of the mountain leafhoppers, the cherry leafhoppers can spread the disease around to other woody hosts. Here are some approaches at management with each host type:

The reservoirs of the disease are carrier chickens which could be health but harboring the disease or chronically sick chickens. The disease affects all ages of chickens. The disease can persist in the flock for 2-3 weeks and signs of the disease are seen between 1–3 days post infection. Transmission of the disease is through direct interaction, airborne droplets and drinking contaminated water. Chicken having infection and those carriers contribute highly to the disease transmission

Cherry X disease also known as Cherry Buckskin disease is caused by a plant pathogenic phytoplasma. Phytoplasma's are obligate parasites of plants and insects. They are specialized bacteria, characterized by their lack of a cell wall, often transmitted through insects, and are responsible for large losses in crops, fruit trees, and ornamentals. The phytoplasma causing Cherry X disease has a fairly limited host range mostly of stone fruit trees. Hosts of the pathogen include sweet/sour cherries, choke cherry, peaches, nectarines, almonds, clover, and dandelion. Most commonly the pathogen is introduced into economical fruit orchards from wild choke cherry and herbaceous weed hosts. The pathogen is vectored by mountain and cherry leafhoppers. The mountain leafhopper vectors the pathogen from wild hosts to cherry orchards but does not feed on the other hosts. The cherry leafhopper which feeds on the infected cherry trees then becomes the next vector that transmits from cherry orchards to peach, nectarine, and other economic crops. Control of Cherry X disease is limited to controlling the spread, vectors, and weed hosts of the pathogen. Once the pathogen has infected a tree it is fatal and removal is necessary to stop it from becoming a reservoir for vectors.

The disease is regarded as extremely rare, with an incidence (new number of cases per year) of one case per million people. The patients are predominantly male (86% in a survey of American patients), although in some countries the rate of women receiving a diagnosis of Whipple's disease has increased in recent years. It occurs predominantly in those of Caucasian ethnicity, suggesting a genetic predisposition in that population.

"T. whipplei" appears to be an environmental organism that is commonly present in the gasterointestinal tract but remains asymptomatic. Several lines of evidence suggest that some defect—inherited or acquired—in immunity is required for it to become pathogenic. The possible immunological defect may be specific for "T. whipplei", since the disease is not associated with a substantially increased risk of other infections.

The disease is usually diagnosed in middle age (median 49 years). Studies from Germany have shown that age at diagnosis has been rising since the 1960s.

White band disease causes the affected coral tissue to decorticate off the skeleton in a white uniform band for which the disease was given its name. The band, which can range from a few millimeters to 10 centimeters wide, typically works its way from the base of the coral colony up to the coral branch tips. The band progresses up the coral branch at an approximate rate of 5 millimeters per day, causing tissue loss as it works its way to the branch tips. After the tissue is lost, the bare skeleton of the coral may later by colonized by filamentous algae.

There are two variants of white band disease, type I and type II. In Type I of white band disease, the tissue remaining on the coral branch shows no sign of coral bleaching, although the affected colony may appear lighter in color overall. However, a variant of white band disease, known simply as white band disease Type II, which was found on Staghorn colonies near the Bahamas, does produce a margin of bleached tissue before it is lost. Type II of white band disease can be mistaken for coral bleaching. By examining the remaining living coral tissue for bleaching, one can delineate which type of the disease affects a given coral.

Swine vesicular disease (SVD) is an acute, contagious viral disease of swine caused by the swine vesicular disease virus, an enterovirus. It is characterized by fever and vesicles with subsequent ulcers in the mouth and on the snout, feet, and teats. The pathogen is relatively resistant to heat, and can persist for a long time in salted, dried, and smoked meat products. Swine vesicular disease does not cause economically-important disease, but is important due to its similarity to foot-and-mouth disease.

Treatment is with penicillin, ampicillin, tetracycline, or co-trimoxazole for one to two years. Any treatment lasting less than a year has an approximate relapse rate of 40%. Recent expert opinion is that Whipple's disease should be treated with doxycycline with hydroxychloroquine for 12 to 18 months. Sulfonamides (sulfadiazine or sulfamethoxazole) may be added for treatment of neurological symptoms.

There is no vaccine for SVD. Prevention measures are similar to those for foot-and-mouth disease: controlling animals imported from infected areas, and sanitary disposal of garbage from international aircraft and ships, and thorough cooking of garbage. Infected animals should be placed in strict quarantine. Eradication measures for the disease include quarantining infected areas, depopulation and disposal of infected and contact pigs, and cleaning and disinfecting

contaminated premises.

No serious long-term effects are known for this disease, but preliminary evidence suggests, if such symptoms do occur, they are less severe than those associated with Lyme disease.

Infections are treated with antibiotics, particularly doxycycline, and the acute symptoms appear to respond to these drugs.

Pogosta disease is a viral disease, established to be identical with other diseases, Karelian fever and Ockelbo disease. The names are derived from the words Pogosta, Karelia and Ockelbo, respectively.

The symptoms of the disease include usually rash, as well as mild fever and other flu-like symptoms; in most cases the symptoms last less than 5 days. However, in some cases, the patients develop a painful arthritis. There are no known chemical agents available to treat the disease.

It has long been suspected that the disease is caused by a Sindbis-like virus, a positive-stranded RNA virus belonging to the Alphavirus genus and family Togaviridae. In 2002 a strain of Sindbis was isolated from patients during an outbreak of the Pogosta disease in Finland, confirming the hypothesis.

This disease is mainly found in the Eastern parts of Finland; a typical Pogosta disease patient is a middle-aged person who has been infected through a mosquito bite while picking berries in the autumn. The prevalence of the disease is about 100 diagnosed cases every year, with larger outbreaks occurring in 7-year intervals.

Mortality is indirect and caused by complications. After cholangitis occurs, patients typically die within 5–10 years.