The characteristic symptoms of dengue are sudden-onset fever, headache (typically located behind the eyes), muscle and joint pains, and a rash. The alternative name for dengue, "breakbone fever", comes from the associated muscle and joint pains. The course of infection is divided into three phases: febrile, critical, and recovery.

The febrile phase involves high fever, potentially over , and is associated with generalized pain and a headache; this usually lasts two to seven days. Nausea and vomiting may also occur. A rash occurs in 50–80% of those with symptoms in the first or second day of symptoms as flushed skin, or later in the course of illness (days 4–7), as a measles-like rash. A rash described as "islands of white in a sea of red" has also been observed. Some petechiae (small red spots that do not disappear when the skin is pressed, which are caused by broken capillaries) can appear at this point, as may some mild bleeding from the mucous membranes of the mouth and nose. The fever itself is classically biphasic or saddleback in nature, breaking and then returning for one or two days.

In some people, the disease proceeds to a critical phase as fever resolves. During this period, there is leakage of plasma from the blood vessels, typically lasting one to two days. This may result in fluid accumulation in the chest and abdominal cavity as well as depletion of fluid from the circulation and decreased blood supply to vital organs. There may also be organ dysfunction and severe bleeding, typically from the gastrointestinal tract. Shock (dengue shock syndrome) and hemorrhage (dengue hemorrhagic fever) occur in less than 5% of all cases of dengue, however those who have previously been infected with other serotypes of dengue virus ("secondary infection") are at an increased risk. This critical phase, while rare, occurs relatively more commonly in children and young adults.

The recovery phase occurs next, with resorption of the leaked fluid into the bloodstream. This usually lasts two to three days. The improvement is often striking, and can be accompanied with severe itching and a slow heart rate. Another rash may occur with either a maculopapular or a vasculitic appearance, which is followed by peeling of the skin. During this stage, a fluid overload state may occur; if it affects the brain, it may cause a reduced level of consciousness or seizures. A feeling of fatigue may last for weeks in adults.

Typically, people infected with dengue virus are asymptomatic (80%) or have only mild symptoms such as an uncomplicated fever. Others have more severe illness (5%), and in a small proportion it is life-threatening. The incubation period (time between exposure and onset of symptoms) ranges from 3 to 14 days, but most often it is 4 to 7 days. Therefore, travelers returning from endemic areas are unlikely to have dengue if fever or other symptoms start more than 14 days after arriving home. Children often experience symptoms similar to those of the common cold and gastroenteritis (vomiting and diarrhea) and have a greater risk of severe complications, though initial symptoms are generally mild but include high fever.

Yellow fever begins after an incubation period of three to six days. Most cases only cause a mild infection with fever, headache, chills, back pain, fatigue, loss of appetite, muscle pain, nausea, and vomiting. In these cases, the infection lasts only three to four days.

In 15% of cases, however, people enter a second, toxic phase of the disease with recurring fever, this time accompanied by jaundice due to liver damage, as well as abdominal pain. Bleeding in the mouth, the eyes, and the gastrointestinal tract cause vomit containing blood, hence the Spanish name for yellow fever, "vómito negro" ("black vomit"). There may also be kidney failure, hiccups, and delirium.

The toxic phase is fatal in about 20 to 50% of cases, making the overall fatality rate for the disease about 3.0 to 7.5%. However, the fatality rate of those with the toxic phase of the disease may exceed 50%.

Surviving the infection provides lifelong immunity, and normally no permanent organ damage results.

The disease is classically a five-day fever of the relapsing type, rarely exhibiting a continuous course. The incubation period is relatively long, at about two weeks. The onset of symptoms is usually sudden, with high fever, severe headache, pain on moving the eyeballs, soreness of the muscles of the legs and back, and frequently hyperaesthesia of the shins. The initial fever is usually followed in a few days by a single, short rise but there may be many relapses between periods without fever. The most constant symptom is pain in the legs. Recovery takes a month or more. Lethal cases are rare, but in a few cases "the persistent fever might lead to heart failure". Aftereffects may include neurasthenia, cardiac disturbances and myalgia.

About 95% of symptomatic cases report joint pain. This is typically symmetrical and with acute onset, affecting the fingers, toes, ankles, wrists, back, knees and elbows. Fatigue occurs in 90% and fever, myalgia and headache occur in 50–60%.

A rash occurs in 50% of patients and is widespread and maculopapular. Lymphadenopathy occurs commonly; sore throat and coryza less frequently. Diarrhea is rare. About 50% of people report needing time off work with the acute illness. If the rash is unnoticed, these symptoms are quite easily mistaken for more common illnesses like influenza or the common cold. Recovery from the flu symptoms is expected within a month, but, because the virus currently cannot be removed once infection has occurred secondary symptoms of joint and muscle inflammation, pain and stiffness can last for many years.

Less common manifestations include splenomegaly, hematuria and glomerulonephritis. Headache, neck stiffness, and photophobia may occur. There have been three case reports suggesting meningitis or encephalitis.

The infection has a slow onset with fever, malaise, headache and muscular pains, very similar to Malaria symptoms. Petechiae (blood spots) on the upper body and bleeding from the nose and gums are observed when the disease progresses to the hemorrhagic phase, usually within seven days of onset.

After an incubation period around seven days, the disease manifests abruptly with chills, high fevers, muscular and articular pains, severe headache, and photophobia. The location of the bite forms a black ulcerous crust (tache noire). Around the fourth day of the illness, a widespread rash appears, first macular and then maculopapular and sometimes petechial.

"Bartonella quintana" is transmitted by contamination of a skin abrasion or louse-bite wound with the faeces of an infected body louse ("Pediculus humanus corporis"). There have also been reports of an infected louse bite passing on the infection.

Symptoms of the disease may vary widely in severity, but major indicators are arthralgia, arthritis, fever, and rash. The incubation period is 7–9 days. About a third of infections are asymptomatic, particularly in children.

In 80% of cases, the disease is asymptomatic, but in the remaining 20%, it takes a complicated course. The virus is estimated to be responsible for about 5,000 deaths annually. The fever accounts for up to one-third of deaths in hospitals within the affected regions and 10 to 16% of total cases.

After an incubation period of six to 21 days, an acute illness with multiorgan involvement develops. Nonspecific symptoms include fever, facial swelling, and muscle fatigue, as well as conjunctivitis and mucosal bleeding. The other symptoms arising from the affected organs are:

- Gastrointestinal tract

- Nausea

- Vomiting (bloody)

- Diarrhea (bloody)

- Stomach ache

- Constipation

- Dysphagia (difficulty swallowing)

- Hepatitis

- Cardiovascular system

- Pericarditis

- Hypertension

- Hypotension

- Tachycardia (abnormally high heart rate)

- Respiratory tract

- Cough

- Chest pain

- Dyspnoea

- Pharyngitis

- Pleuritis

- Nervous system

- Encephalitis

- Meningitis

- Unilateral or bilateral hearing deficit

- Seizures

Clinically, Lassa fever infections are difficult to distinguish from other viral hemorrhagic fevers such as Ebola and Marburg, and from more common febrile illnesses such as malaria.

The virus is excreted in urine for 3–9 weeks and in semen for three months.

Signs and symptoms of VHFs include (by definition) fever and bleeding. Manifestations of VHF often also include flushing of the face and chest, small red or purple spots (petechiae), bleeding, swelling caused by edema, low blood pressure (hypotension), and shock. Malaise, muscle pain, headache, vomiting, and diarrhea occur frequently. The severity of symptoms varies with the type of virus. The “VHF syndrome” (capillary leak, bleeding diathesis, and circulatory compromise leading to shock) appears in a majority of people with filovirus hemorrhagic fevers (e.g., Ebola and Marburg virus), Crimean–Congo hemorrhagic fever (CCHF), and the South American hemorrhagic fevers caused by arenaviruses, but only in a small minority of patients with dengue, Rift Valley fever, and Lassa fever.

African tick bite fever is often asymptomatic or mild in clinical presentation and complications are rare. The onset of illness is typically 5–7 days after the tick bite, although in some cases it may take up to 10 days for symptoms to occur. Symptoms can persist for several days to up to three weeks. Common presenting symptoms include:

- Fever

- Headache

- Muscle aches

- Inoculation eschar, which is dead, often black, tissue around a bite site (see photo above)

- Eschars may or may not be present. "Amblyomma" ticks actively attack cattle or humans and can bite more than once. In African tick bite fever, unlike what is typically seen with other Rickettsial spotted fevers when only one eschar is identified, multiple eschars may be seen and are considered pathognomonic.

- Swollen lymph nodes near the site of the bite

- Maculopapular and/or vesicular rash

The following signs and symptoms refer to epidemic typhus as it is the most important of the typhus group of diseases.

Signs and symptoms begin with sudden onset of fever, and other flu-like symptoms about one to two weeks after being infected. Five to nine days after the symptoms have started, a rash typically begins on the trunk and spreads to the extremities. This rash eventually spreads over most of the body, sparing the face, palms, and soles. Signs of meningoencephalitis begin with the rash and continue into the second or third weeks. Other signs of meningoencephalitis include sensitivity to light (photophobia), altered mental status (delirium), or coma. Untreated cases are often fatal.

Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains particularly in the back, and headaches. Symptoms typically improve within five days. In about 15% of people within a day of improving, the fever comes back, abdominal pain occurs, and liver damage begins causing yellow skin. If this occurs, the risk of bleeding and kidney problems is also increased.

The disease is caused by the yellow fever virus and is spread by the bite of an infected female mosquito. It infects only humans, other primates, and several species of mosquitoes. In cities, it is spread primarily by "Aedes aegypti", a type of mosquito found throughout the tropics and subtropics. The virus is an RNA virus of the genus "Flavivirus". The disease may be difficult to tell apart from other illnesses, especially in the early stages. To confirm a suspected case, blood sample testing with polymerase chain reaction is required.

A safe and effective vaccine against yellow fever exists and some countries require vaccinations for travelers. Other efforts to prevent infection include reducing the population of the transmitting mosquito. In areas where yellow fever is common and vaccination is uncommon, early diagnosis of cases and immunization of large parts of the population is important to prevent outbreaks. Once infected, management is symptomatic with no specific measures effective against the virus. Death occurs in up to half of those who get severe disease.

In 2013, yellow fever resulted in about 127,000 severe infections and 45,000 deaths, with nearly 90% of these occurring in Africa. Nearly a billion people live in an area of the world where the disease is common. It is common in tropical areas of South America and Africa, but not in Asia. Since the 1980s, the number of cases of yellow fever has been increasing. This is believed to be due to fewer people being immune, more people living in cities, people moving frequently, and changing climate. The disease originated in Africa, from where it spread to South America through the slave trade in the 17th century. Since the 17th century, several major outbreaks of the disease have occurred in the Americas, Africa, and Europe. In the 18th and 19th centuries, yellow fever was seen as one of the most dangerous infectious diseases. In 1927 yellow fever virus became the first human virus to be isolated.

Complications are rare and are not life-threatening. No deaths due to African tick bite fever have been reported. Reported complications include:

- Prolonged fever > 3 weeks in duration

- Reactive arthritis

- Moderate to severe headache

The incubation period of the chikungunya virus ranges from one to twelve days, and is most typically three to seven. The disease may be asymptomatic, but generally is not, as 72% to 97% of those infected will develop symptoms. Characteristic symptoms include sudden onset with high fever, joint pain, and rash. Other symptoms may occur, including headache, fatigue, digestive complaints, and conjunctivitis.

Information gained during recent epidemics suggests that chikungunya fever may result in a chronic phase as well as the phase of acute illness. Within the acute phase, two stages have been identified: a viral stage during the first five to seven days, during which viremia occurs, followed by a convalescent stage lasting approximately ten days, during which symptoms improve and the virus cannot be detected in the blood. Typically, the disease begins with a sudden high fever that lasts from a few days to a week, and sometimes up to ten days. The fever is usually above and sometimes reaching and may be biphasic—lasting several days, breaking, and then returning. Fever occurs with the onset of viremia, and the level of virus in the blood correlates with the intensity of symptoms in the acute phase. When IgM, an antibody that is a response to the initial exposure to an antigen, appears in the blood, viremia begins to diminish. However, headache, insomnia and an extreme degree of exhaustion remain, usually about five to seven days.

Following the fever, strong joint pain or stiffness occurs; it usually lasts weeks or months, but may last for years. The joint pain can be debilitating, often resulting in near immobility of the affected joints. Joint pain is reported in 87–98% of cases, and nearly always occurs in more than one joint, though joint swelling is uncommon. Typically the affected joints are located in both arms and legs, and are affected symmetrically. Joints are more likely to be affected if they have previously been damaged by disorders such as arthritis. Pain most commonly occurs in peripheral joints, such as the wrists, ankles, and joints of the hands and feet as well as some of the larger joints, typically the shoulders, elbows and knees. Pain may also occur in the muscles or ligaments.

Rash occurs in 40–50% of cases, generally as a maculopapular rash occurring two to five days after onset of symptoms. Digestive symptoms, including abdominal pain, nausea, vomiting or diarrhea, may also occur. In more than half of cases, normal activity is limited by significant fatigue and pain. Infrequently, inflammation of the eyes may occur in the form of iridocyclitis, or uveitis, and retinal lesions may occur.

Temporary damage to the liver may occur.

Rarely, neurological disorders have been reported in association with chikungunya virus, including Guillain–Barré syndrome, palsies, meningoencephalitis, flaccid paralysis and neuropathy. In contrast to dengue fever, Chikungunya fever very rarely causes hemorrhagic complications. Symptoms of bleeding should lead to consideration of alternative diagnoses or co-infection with dengue fever or coexisting congestive hepatopathy.

A few days after the infective bite, a feeling of lassitude, abdominal distress and chills develop followed by fever of 39 °C to 40 °C, severe frontal headaches, muscle and joint aches, flushing of the face and a fast heart rate. After two days the fever begins to subside and the temperature returns to normal. Fatigue, a slow heart rate and low blood pressure may persist from few days to several weeks but complete recovery is the rule.

Bolivian hemorrhagic fever (BHF), also known as black typhus or Ordog Fever, is a hemorrhagic fever and zoonotic infectious disease originating in Bolivia after infection by Machupo virus.

BHF was first identified in 1963 as an ambisense RNA virus of the Arenaviridae family, by a research group led by Karl Johnson. The mortality rate is estimated at 5 to 30 percent. Due to its pathogenicity, Machupo virus requires Biosafety Level Four conditions, the highest level.

In February and March 2007, some 20 suspected BHF cases (3 fatal) were reported to the El Servicio Departamental de Salud (SEDES) in Beni Department, Bolivia, and in February 2008, at least 200 suspected new cases (12 fatal) were reported to SEDES. In November 2011, a SEDES expert involved in a serosurvey to determine the extent of Machupo virus infections in the Department after the discovery of a second confirmed case near the departmental capital of Trinidad in November, 2011, expressed concern about expansion of the virus' distribution outside the endemic zone in Mamoré and Iténez provinces.

Multiple diseases include the word "typhus" in their description. Types include:

Lassa fever, also known as Lassa hemorrhagic fever (LHF), is a type of viral hemorrhagic fever caused by the Lassa virus. Many of those infected by the virus do not develop symptoms. When symptoms occur they typically include fever, weakness, headaches, vomiting, and muscle pains. Less commonly there may be bleeding from the mouth or gastrointestinal tract. The risk of death once infected is about one percent and frequently occurs within two weeks of the onset of symptoms. Among those who survive about a quarter have deafness which improves over time in about half.

The disease is usually initially spread to people via contact with the urine or feces of an infected multimammate rat. Spread can then occur via direct contact between people. Diagnosis based on symptoms is difficult. Confirmation is by laboratory testing to detect the virus's RNA, antibodies for the virus, or the virus itself in cell culture. Other conditions that may present similarly include Ebola fever, malaria, typhoid fever, and yellow fever. The Lassa virus is a member of the "Arenaviridae" virus family.

There is no vaccine. Prevention requires isolating those who are infected and decreasing contact with the rats. Other efforts to control the spread of disease include having a cat to hunt vermin, and storing food in sealed containers. Treatment is directed at addressing dehydration and improving symptoms. The antiviral medication, ribavirin may be useful when given early. These measures improve outcomes.

Descriptions of the disease date from the 1950s. The virus was first described in 1969 from a case in the town of Lassa, in Borno State, Nigeria. Lassa fever is relatively common in West Africa including the countries of Nigeria, Liberia, Sierra Leone, Guinea, and Ghana. There are about 300,000 to 500,000 cases which result in 5,000 deaths a year.

The diagnosis is made with serologic methods, either the classic Weil-Felix test

(agglutination of Proteus OX strains ), ELISA, or immunofluorescence assays in the bioptic material of the primary lesion.

Spotted fever can be very difficult to diagnose in its early stages, and even experienced doctors who are familiar with the disease find it hard to detect.

People infected with "R. rickettsii" usually notice symptoms following an incubation period of one to two weeks after a tick bite. The early clinical presentation of Rocky Mountain spotted fever is nonspecific and may resemble a variety of other infectious and non-infectious diseases.

Initial symptoms:

- Fever

- Nausea

- Emesis (vomiting)

- Severe headache

- Muscle pain

- Lack of appetite

- Parotitis in some cases (somewhat rare)

Later signs and symptoms:

- Maculopapular rash

- Petechial rash

- Abdominal pain

- Joint pain

- Conjunctivitis

- Forgetfulness

The classic triad of findings for this disease are fever, rash, and history of tick bite. However, this combination is often not identified when the patient initially presents for care. The rash has a centripetal, or "inward" pattern of spread, meaning it begins at the extremities and courses towards the trunk.

The rash first appears two to five days after the onset of fever, and it is often quite subtle. Younger patients usually develop the rash earlier than older patients. Most often the rash begins as small, flat, pink, non-itchy spots (macules) on the wrists, forearms, and ankles. These spots turn pale when pressure is applied and eventually become raised on the skin. The characteristic red, spotted (petechial) rash of Rocky Mountain spotted fever is usually not seen until the sixth day or later after onset of symptoms, but this type of rash occurs in only 35 to 60% of patients with Rocky Mountain spotted fever. The rash involves the palms or soles in as many as 80% of the patients. However, this distribution may not occur until later on in the course of the disease. As many as 15 percent of patients may never develop a rash.

A spotted fever is a type of tick-borne disease which presents on the skin. They are all caused by bacteria of the genus "Rickettsia". Typhus is a group of similar diseases also caused by "Rickettsia" bacteria, but spotted fevers and typhus are different clinical entities.

The phrase apparently originated in Spain in the seventeenth century and was ‘loosely applied in England to typhus or any fever involving petechial eruptions.’ During the seventeenth and eighteenth centuries, it was thought to be ‘“cousin-germane” to and herald of the bubonic plague’, a disease which periodically afflicted the city of London and its environs during the sixteenth and seventeenth centuries, most notably during the Great Plague of 1665.

Types of spotted fevers include:

- Mediterranean spotted fever

- Rocky Mountain spotted fever

- Queensland tick typhus

- Helvetica Spotted fever

Kyasanur Forest disease (KFD) is a tick-borne viral hemorrhagic fever endemic to South Asia. The disease is caused by a virus belonging to the family "Flaviviridae", which also includes yellow fever and dengue fever.

Most people who are infected develop sickness between five and 15 days after they are bitten. The symptoms may include a sudden fever, chills, headaches, muscle or joint aches, and nausea. A rash may also occur. These symptoms usually continue for two to 9 days, then disappear. This cycle may continue for several weeks if the person is not treated.