Presumptive diagnosis is made by characteristic clinical signs, post mortem lesions, and presence of competent vectors. Laboratory confirmation is by viral isolation, with such techniques as quantitative PCR for detecting viral RNA, antigen capture (ELISA), and immunofluorescence of infected tissues. Serological tests are only useful for detecting recovered animals, as sick animals die before they are able to mount effective immune responses.

The gold standard for diagnosis is identification of trypanosomes in a patient sample by microscopic examination. Patient samples that can be used for diagnosis include chancre fluid, lymph node aspirates, blood, bone marrow, and, during the neurological stage, cerebrospinal fluid. Detection of trypanosome-specific antibodies can be used for diagnosis, but the sensitivity and specificity of these methods are too variable to be used alone for clinical diagnosis. Further, seroconversion occurs after the onset of clinical symptoms during a "T. b. rhodesiense" infection, so is of limited diagnostic use.

Trypanosomes can be detected from patient samples using two different preparations. A wet preparation can be used to look for the motile trypanosomes. Alternatively, a fixed (dried) smear can be stained using Giemsa's or Field's technique and examined under a microscope. Often, the parasite is in relatively low abundance in the sample, so techniques to concentrate the parasites can be used prior to microscopic examination. For blood samples, these include centrifugation followed by examination of the buffy coat; mini anion-exchange/centrifugation; and the quantitative buffy coat (QBC) technique. For other samples, such as spinal fluid, concentration techniques include centrifugation followed by examination of the sediment.

Three serological tests are also available for detection of the parasite: the micro-CATT, wb-CATT, and wb-LATEX. The first uses dried blood, while the other two use whole blood samples. A 2002 study found the wb-CATT to be the most efficient for diagnosis, while the wb-LATEX is a better exam for situations where greater sensitivity is required.

There is currently no treatment for AHS.

Control of an outbreak in an endemic region involves quarantine, vector control and vaccination. To prevent this disease, the affected horses are usually slaughtered, and the uninfected horses are vaccinated against the virus. Three vaccines currently exist, which include a polyvalent vaccine, a monovalent vaccine, and a monovalent inactivated vaccine. This disease can also be prevented by destroying the insect vector habitats using insecticides.

Currently there are few medically related prevention options for African Trypanosomiasis (i.e. no vaccine exists for immunity). Although the risk of infection from a tsetse fly bite is minor (estimated at less than 0.1%), the use of insect repellants, wearing long-sleeved clothing, avoiding tsetse-dense areas, implementing bush clearance methods and wild game culling are the best options to avoid infection available for local residents of affected areas.

At the 25th ISCTRC (International Scientific Council for Trypanosomiasis Research and Control) in Mombasa, Kenya, in October 1999, the idea of an African-wide initiative to control tsetse and trypanosomiasis populations was discussed. During the 36th summit of the Organization for African Unity in Lome, Togo, in July 2000, a resolution was passed to form the Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC). The campaign works to eradicate the tsetse vector population levels and subsequently the protozoan disease, by use of insecticide-impregnated targets, fly traps, insecticide-treated cattle, ultra-low dose aerial/ground spraying (SAT) of tsetse resting sites and the sterile insect technique (SIT). The use of SIT in Zanzibar proved effective in eliminating the entire population of tsetse flies but was expensive and is relatively impractical to use in many of the endemic countries afflicted with African trypanosomiasis.

Regular active surveillance, involving detection and prompt treatment of new infections, and tsetse fly control is the backbone of the strategy used to control sleeping sickness. Systematic screening of at-risk communities is the best approach, because case-by-case screening is not practical in endemic regions. Systematic screening may be in the form of mobile clinics or fixed screening centres where teams travel daily to areas of high infection rates. Such screening efforts are important because early symptoms are not evident or serious enough to warrant patients with gambiense disease to seek medical attention, particularly in very remote areas. Also, diagnosis of the disease is difficult and health workers may not associate such general symptoms with trypanosomiasis. Systematic screening allows early-stage disease to be detected and treated before the disease progresses, and removes the potential human reservoir. A single case of sexual transmission of West African sleeping sickness has been reported.

Diagnosis can be assisted with a number of different scoring systems.

Travelers who are susceptible to motion sickness can minimize symptoms by:

- Choosing a window seat with a view of the ground or of lower clouds, such that motion can be detected. This will not work if the plane is flown in the clouds for a long duration.

- Choosing seats with the smoothest ride in regards to pitch (the seats over the wings in an airplane). (This may not be sufficient for sensitive individuals who need to see ground movement)

- Sitting facing forward while focusing on distant objects rather than trying to read or look at something inside the airplane.

- Eating dry crackers, olives or suck on a lemon, to dry out the mouth, lessening nausea.

- Drinking a carbonated beverage.

The cause is the most mysterious aspect of the disease. Commentators then and now put much blame on the generally poor sanitation, sewage and contaminated water supplies of the time, which might have harboured the source of infection. The first outbreak at the end of the Wars of the Roses means that it may have been brought over from France by the French mercenaries whom Henry VII used to gain the English throne. However, the "Croyland Chronicle" mentions that Thomas Stanley, 1st Earl of Derby used the "sweating sickness" as an excuse not to join with Richard III's army prior to the Battle of Bosworth.

Relapsing fever has been proposed as a possible cause. This disease, which is spread by ticks and lice, occurs most often during the summer months, as did the original sweating sickness. However, relapsing fever is marked by a prominent black scab at the site of the tick bite and a subsequent skin rash.

Noting symptom overlap with hantavirus pulmonary syndrome, several scientists proposed an unknown hantavirus as the cause. A critique of this hypothesis included the argument that, whereas sweating sickness was thought to be transmitted from human to human, hantaviruses are rarely spread in this way. However, infection via human-to-human contact has been proven in hantavirus outbreaks in Argentina.

Decompression sickness should be suspected if any of the symptoms associated with the condition occurs following a drop in pressure, in particular, within 24 hours of diving. In 1995, 95% of all cases reported to Divers Alert Network had shown symptoms within 24 hours. An alternative diagnosis should be suspected if severe symptoms begin more than six hours following decompression without an altitude exposure or if any symptom occurs more than 24 hours after surfacing. The diagnosis is confirmed if the symptoms are relieved by recompression. Although MRI or CT can frequently identify bubbles in DCS, they are not as good at determining the diagnosis as a proper history of the event and description of the symptoms.

Ascending slowly is the best way to avoid altitude sickness. Avoiding strenuous activity such as skiing, hiking, etc. in the first 24 hours at high altitude reduces the symptoms of AMS. Alcohol and sleeping pills are respiratory depressants, and thus slow down the acclimatization process and should be avoided. Alcohol also tends to cause dehydration and exacerbates AMS. Thus, avoiding alcohol consumption in the first 24–48 hours at a higher altitude is optimal.

There are numerous alternative remedies for motion sickness. One such is ginger, but it is ineffective.

To prevent the excess formation of bubbles that can lead to decompression sickness, divers limit their ascent rate—the recommended ascent rate used by popular decompression models is about per minute—and carry out a decompression schedule as necessary. This schedule requires the diver to ascend to a particular depth, and remain at that depth until sufficient gas has been eliminated from the body to allow further ascent. Each of these is termed a "decompression stop", and a schedule for a given bottom time and depth may contain one or more stops, or none at all. Dives that contain no decompression stops are called "no-stop dives", but divers usually schedule a short "safety stop" at , , or , depending on the training agency.

The decompression schedule may be derived from decompression tables, decompression software, or from dive computers, and these are commonly based upon a mathematical model of the body's uptake and release of inert gas as pressure changes. These models, such as the Bühlmann decompression algorithm, are designed to fit empirical data and provide a decompression schedule for a given depth and dive duration.

Since divers on the surface after a dive still have excess inert gas in their bodies, any subsequent dive before this excess is fully eliminated needs to modify the schedule to take account of the residual gas load from the previous dive. This will result in a shorter available time under water or an increased decompression time during the subsequent dive. The total elimination of excess gas may take many hours, and tables will indicate the time at normal pressures that is required, which may be up to 18 hours.

Decompression time can be significantly shortened by breathing mixtures containing much less inert gas during the decompression phase of the dive (or pure oxygen at stops in of water or less). The reason is that the inert gas outgases at a rate proportional to the difference between the partial pressure of inert gas in the diver's body and its partial pressure in the breathing gas; whereas the likelihood of bubble formation depends on the difference between the inert gas partial pressure in the diver's body and the ambient pressure. Reduction in decompression requirements can also be gained by breathing a nitrox mix during the dive, since less nitrogen will be taken into the body than during the same dive done on air.

Following a decompression schedule does not completely protect against DCS. The algorithms used are designed to reduce the probability of DCS to a very low level, but do not reduce it to zero.

The symptoms and signs, as described by physician John Caius and others, were as follows: the disease began very suddenly with a sense of apprehension, followed by cold shivers (sometimes very violent), giddiness, headache, and severe pains in the neck, shoulders and limbs, with great exhaustion. After the cold stage, which might last from half an hour to three hours, the hot and sweating stage followed. The characteristic sweat broke out suddenly without any obvious cause. Accompanying the sweat, or after, was a sense of heat, headache, delirium, rapid pulse, and intense thirst. Palpitation and pain in the heart were frequent symptoms. No skin eruptions were noted by observers including Caius. In the final stages, there was either general exhaustion and collapse, or an irresistible urge to sleep, which Caius thought to be fatal if the patient was permitted to give way to it. One attack did not offer immunity, and some people suffered several bouts before dying. The disease tended to occur in summer and early autumn.

There are no tests required to diagnose widow spider bites, or latrodectism symptoms. The diagnosis is clinical and based on historic evidence of widow spider bites. Pathognomonic symptoms such as localized sweating and piloerection provide evidence of envenomation. Unlike the brown recluse, the widow species are easily identified by most people.

Diagnosis is obvious in most people reporting contact with a "Latrodectus" spider. However, without a spider, either through inability to communicate or unawareness, the diagnosis may be missed as symptoms overlap with a variety of other serious clinical syndromes such as tetanus or acute abdomen. Blood values are typically unimportant but may be needed to show myocarditis or dehydration from vomiting.

As astronauts frequently have motion sickness, NASA has done extensive research on the causes and treatments for motion sickness. One very promising looking treatment is for the person suffering from motion sickness to wear LCD shutter glasses that create a stroboscopic vision of 4 Hz with a dwell of 10 milliseconds.

Over-the-counter and prescription medications are readily available, such as dimenhydrinate, scopolamine, meclizine, promethazine, cyclizine, and cinnarizine. Cinnarizine is not available in the United States, as it is not approved by the FDA. As these medications often have side effects, anyone involved in high-risk activities while at sea (such as SCUBA divers) must evaluate the risks versus the benefits. Promethazine is especially known to cause drowsiness, which is often counteracted by ephedrine in a combination known as "the Coast Guard cocktail.". There are special considerations to be aware of when the common anti-motion sickness medications are used in the military setting where performance must be maintained at a high level.

Scopolamine is effective and is sometimes used in the form of transdermal patches (1.5 mg) or as a newer tablet form (0.4 mg). The selection of a transdermal patch or scopolamine tablet is determined by a doctor after consideration of the patient's age, weight, and length of treatment time required.

Many pharmacological treatments which are effective for nausea and vomiting in some medical conditions may not be effective for motion sickness. For example, metoclopramide and prochlorperazine, although widely used for nausea, are ineffective for motion-sickness prevention and treatment. This is due to the physiology of the CNS vomiting centre and its inputs from the chemoreceptor trigger zone versus the inner ear. Sedating anti-histamine medications such as promethazine work quite well for motion sickness, although they can cause significant drowsiness.

Ginger root is commonly thought to be an effective anti-emetic, but it is ineffective in treating motion sickness.

The term Winterbottom's sign derives from descriptions of the posterior cervical lymphadenopathy associated with African trypanosomiasis made by a slave trader using the sign to weed out the ill.

The vast majority of victims fully recover without significant lasting problems (sequelae). Death from latrodectism is reported as high as 5% to as low as 0.2%. In the United States, where antivenom is rarely used, there have been no deaths reported for decades.

Despite frequent reference to youth and old age being a predisposing factor it has been demonstrated that young children appear to be at lowest risk for a serious bite, perhaps owing to the rapid use of antivenom. Bite victims who are very young, old, hypotensive, pregnant or who have existing heart problems are reported to be the most likely to suffer complications. However, due to the low incidence of complications these generalizations simply refer to special complications (see Special circumstances).

Human milk sickness is uncommon today in the United States. Current practices of animal husbandry generally control the pastures and feed of cattle, and the pooling of milk from many producers lowers the risk of tremetol present in dangerous amounts. The poison tremetol is not inactivated by pasteurization. Although extremely rare, milk sickness can occur if a person drinks contaminated milk or eats dairy products gathered from a single cow or from a smaller herd that has fed on the white snakeroot plant. There is no cure, but treatment is available.

Diagnosis is based on history given by patient, including recent medications.

Winterbottom's sign is seen in the early phase of African trypanosomiasis, a disease caused by the parasites "Trypanosoma brucei rhodesiense" and "Trypanosoma brucei gambiense" which is more commonly known as African sleeping sickness. Dr. Anthony Martinelli describes Winterbottom's sign as the swelling of lymph nodes (lymphadenopathy) along the back of the neck, in the posterior cervical chain of lymph nodes, as trypanosomes travel in the lymphatic fluid and cause inflammation.

It may be suggestive of cerebral infection.

Mild disease can be treated with fluids by mouth. In more significant disease spraying with mist and using a fan is useful. For those with severe disease putting them in lukewarm water is recommended if possible with transport to a hospital.

Milk sickness, also known as tremetol vomiting or, in animals, as trembles, is a kind of poisoning, characterized by trembling, vomiting, and severe intestinal pain, that affects individuals who ingest milk, other dairy products, or meat from a cow that has fed on white snakeroot plant, which contains the poison tremetol.

Although very rare today, milk sickness claimed thousands of lives among migrants to the Midwest in the early 19th century in the United States, especially in frontier areas along the Ohio River Valley and its tributaries where white snakeroot was prevalent. New settlers were unfamiliar with the plant and its properties. A notable victim was Nancy Hanks Lincoln, the mother of Abraham Lincoln, who died in 1818. Nursing calves and lambs may have died from their mothers' milk contaminated with snakeroot, although the adult cows and sheep showed no signs of poisoning. Cattle, horses, and sheep are the animals most often poisoned.

Anna Pierce Hobbs Bixby, called Dr. Anna on the frontier, is credited today by the American medical community with having identified white snakeroot as the cause of the illness. Told about the plant's properties by an elderly Shawnee woman she befriended, Bixby did testing to observe and document evidence. She wrote up her findings to share the discovery in the medical world. The Shawnee woman's name has been lost to history.

Sweating sickness is "an acute, febrile, tickborne toxicosis characterized mainly by a profuse, moist eczema and hyperemia of the skin and visible mucous membranes." It affects cattle, mainly calves, mostly in southern and eastern Africa. It is caused by toxins that develop in some ticks of the "Hyalomma truncatum" species.

Avoidance of antitoxins that may cause serum sickness is the best way to prevent serum sickness. Although, sometimes, the benefits outweigh the risks in the case of a life-threatening bite or sting. Prophylactic antihistamines or corticosteroids may be used concomitant with the antitoxin. Skin testing may be done beforehand in order to identify individuals who may be at risk of a reaction. Physicians should make their patients aware of the drugs or antitoxins to which they are allergic if there is a reaction. The physician will then choose an alternate antitoxin if it's appropriate or continue with prophylactic measures.

In sheep, the disease is also called the "circling disease". The most obvious signs for the veterinarians are neurological, especially lateral deviation of the neck and head.