The pathogenic agent is found everywhere except New Zealand. The bacterium is extremely sustainable and virulent: a single organism is able to cause an infection. The common source of infection is inhalation of contaminated dust, contact with contaminated milk, meat, or wool, and particularly birthing products. Ticks can transfer the pathogenic agent to other animals. Transfer between humans seems extremely rare and has so far been described in very few cases.

Some studies have shown more men to be affected than women, which may be attributed to different employment rates in typical professions.

“At risk” occupations include:

- Veterinary personnel

- Stockyard workers

- Farmers

- Sheep shearers

- Animal transporters

- Laboratory workers handling potentially infected veterinary samples or visiting abattoirs

- People who cull and process kangaroos

- Hide (tannery) workers

Currently, no vaccine against relapsing fever is available, but research continues. Developing a vaccine is very difficult because the spirochetes avoid the immune response of the infected person (or animal) through antigenic variation. Essentially, the pathogen stays one step ahead of antibodies by changing its surface proteins. These surface proteins, lipoproteins called variable major proteins, have only 30–70% of their amino acid sequences in common, which is sufficient to create a new antigenic "identity" for the organism. Antibodies in the blood that are binding to and clearing spirochetes expressing the old proteins do not recognize spirochetes expressing the new ones. Antigenic variation is common among pathogenic organisms. These include the agents of malaria, gonorrhea, and sleeping sickness. Important questions about antigenic variation are also relevant for such research areas as developing a vaccine against HIV and predicting the next influenza pandemic.

As of 2017 there is no commercially available vaccine. A vaccine has been in development for scrub typhus known as the scrub typhus vaccine.

Rocky Mountain spotted fever can be a very severe illness and patients often require hospitalization. Because "R. rickettsii" infects the cells lining blood vessels throughout the body, severe manifestations of this disease may involve the respiratory system, central nervous system, gastrointestinal system, or kidneys.

Long-term health problems following acute Rocky Mountain spotted fever infection include partial paralysis of the lower extremities, gangrene requiring amputation of fingers, toes, or arms or legs, hearing loss, loss of bowel or bladder control, movement disorders, and language disorders. These complications are most frequent in persons recovering from severe, life-threatening disease, often following lengthy hospitalizations

The disease can be fatal if left untreated, but endemic typhus is highly treatable with antibiotics. Most people recover fully, but death may occur in the elderly, severely disabled or patients with a depressed immune system. The most effective antibiotics include tetracycline and chloramphenicol. In United States, CDC recommends solely doxycycline.

Protection is offered by Q-Vax, a whole-cell, inactivated vaccine developed by an Australian vaccine manufacturing company, CSL Limited. The intradermal vaccination is composed of killed "C. burnetii" organisms. Skin and blood tests should be done before vaccination to identify pre-existing immunity, because vaccinating people who already have an immunity can result in a severe local reaction. After a single dose of vaccine, protective immunity lasts for many years. Revaccination is not generally required. Annual screening is typically recommended.

In 2001, Australia introduced a national Q fever vaccination program for people working in “at risk” occupations. Vaccinated or previously exposed people may have their status recorded on the Australian Q Fever Register, which may be a condition of employment in the meat processing industry. An earlier killed vaccine had been developed in the Soviet Union, but its side effects prevented its licensing abroad.

Preliminary results suggest vaccination of animals may be a method of control. Published trials proved that use of a registered phase vaccine (Coxevac) on infected farms is a tool of major interest to manage or prevent early or late abortion, repeat breeding, anoestrus, silent oestrus, metritis, and decreases in milk yield when "C. burnetii" is the major cause of these problems.

There are only between 500 and 2500 cases of Rocky Mountain spotted fever reported in the United States per year, and in only about 20% can the tick be found.

Host factors associated with severe or fatal Rocky Mountain spotted fever include advanced age, male sex, African or Caribbean background, chronic alcohol abuse, and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Deficiency of G6PD is a genetic condition affecting about 12 percent of the Afro-American male population. Deficiency in this enzyme is associated with a high proportion of severe cases of Rocky Mountain spotted fever. This is a rare clinical complication that is often fatal within five days of the onset of the disease.

In the early 1940´s, outbreaks were described in the Mexican states of Sinaloa, Sonora, Durango, and Coahuila driven by dogs and Rhipicephalus sanguineus sensu lato, the brown dog tick. Over the ensuing 100 years case fatality rates were 30%–80%. In 2015, there was an abrupt rise in Sonora cases with 80 fatal cases. From 2003 to 2016, cases increased to 1394 with 247 deaths.

"Rickettsia africae" is a gram-negative, obligate intracellular, pleomorphic bacterium. It belongs to the "Rickettsia" genus, which includes many bacterial species that are transmitted to humans by arthropods.

It is caused by the bacteria "Rickettsia typhi", and is transmitted by the fleas that infest rats. While rat fleas are the most common vectors, cat fleas and mouse fleas are less common modes of transmission. These fleas are not affected by the infection. Human infection occurs because of flea-fecal contamination of the bites on human skin. Rats, cats, opossums maintain the rickettsia colonization by providing it with a host for its entire life cycle. Rats can develop the infection, and help spread the infection to other fleas that infect them, and help multiply the number of infected fleas that can then infect humans.

Less often, endemic typhus is caused by "Rickettsia felis" and transmitted by fleas carried by cats or opossums.

In the United States of America, murine typhus is found most commonly in southern California, Texas and Hawaii. In some studies, up to 13% of children were found to have serological evidence of infection.

Yellow fever is common in tropical and subtropical areas of South America and Africa. Worldwide, about 600 million people live in endemic areas. The WHO estimates 200,000 cases of disease and 30,000 deaths a year occur; the number of officially reported cases is far lower.

Along with "Rickettsia prowazekii" and "Bartonella quintana", "Borrelia recurrentis" is one of three pathogens of which the body louse ("Pediculus humanus humanus") is a vector. Louse-borne relapsing fever is more severe than the tick-borne variety.

Louse-borne relapsing fever occurs in epidemics amid poor living conditions, famine and war in the developing world. It is currently prevalent in Ethiopia and Sudan.

Mortality rate is 1% with treatment and 30–70% without treatment. Poor prognostic signs include severe jaundice, severe change in mental status, severe bleeding and a prolonged QT interval on ECG.

Lice that feed on infected humans acquire the "Borrelia" organisms that then multiply in the gut of the louse. When an infected louse feeds on an uninfected human, the organism gains access when the victim crushes the louse or scratches the area where the louse is feeding. "B. recurrentis" infects the person via mucous membranes and then invades the bloodstream. No non-human, animal reservoir exists.

They are usually spread by eating or drinking food or water contaminated with the feces of an infected person. They may occur when a person who prepares food is infected. Risk factors include poor sanitation as is found among poor crowded populations. Occasionally they may be transmitted by sex. Humans are the only animal infected.

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

Paratyphoid B is more frequent in Europe. It can present as a typhoid-like illness, as a severe gastroenteritis or with features of both. Herpes labialis, rare in true typhoid fever, is frequently seen in paratyphoid B. Diagnosis is with isolation of the agent in blood or stool and demonstration of antibodies antiBH in the Widal test. The disease responds well to chloramphenicol or co-trimoxazole.

Prevention of ATBF centers around protecting oneself from tick bites by wearing long pants and shirt, and using insecticides like DEET on the skin. Travelers to rural areas in Africa and the West Indies should be aware that they may come in contact with ATBF tick vectors. Infection is more likely to occur in people who are traveling to rural areas or plan to spend time participating in outdoor activities. Extra caution should be taken in November - April, when "Amblyomma" ticks are more active. Inspection of the body, clothing, gear, and any pets after time outdoors can help to identify and remove ticks early.

Vaccination is recommended for those traveling to affected areas, because non-native people tend to develop more severe illness when infected. Protection begins by the 10th day after vaccine administration in 95% of people, and had been reported to last for at least 10 years. WHO now states that a single dose of vaccination is sufficient to confer lifelong immunity against yellow fever disease." The attenuated live vaccine stem 17D was developed in 1937 by Max Theiler. The World Health Organization (WHO) recommends routine vaccinations for people living in affected areas between the 9th and 12th month after birth.

Up to one in four people experience fever, aches, and local soreness and redness at the site of injection. In rare cases (less than one in 200,000 to 300,000), the vaccination can cause yellow fever vaccine–associated viscerotropic disease, which is fatal in 60% of cases. It is probably due to the genetic morphology of the immune system. Another possible side effect is an infection of the nervous system, which occurs in one in 200,000 to 300,000 cases, causing yellow fever vaccine-associated neurotropic disease, which can lead to meningoencephalitis and is fatal in less than 5% of cases.

The Yellow Fever Initiative, launched by WHO in 2006, vaccinated more than 105 million people in 14 countries in West Africa. No outbreaks were reported during 2015. The campaign was supported by the GAVI Alliance, and governmental organizations in Europe and Africa. According to the WHO, mass vaccination cannot eliminate yellow fever because of the vast number of infected mosquitoes in urban areas of the target countries, but it will significantly reduce the number of people infected.

In March 2017, WHO launched a vaccination campaign in Brazil with 3.5 million doses from an emergency stockpile. In March 2017 the WHO recommended vaccination for travellers to certain parts of Brazil.

The American Public Health Association recommends treatment based upon clinical findings and before culturing confirms the diagnosis. Without treatment, death may occur in 10 to 60 percent of patients with epidemic typhus, with patients over age 60 having the highest risk of death. In the antibiotic era, death is uncommon if doxycycline is given. In one study of 60 hospitalized patients with epidemic typhus, no patient died when given doxycycline or chloramphenicol. Some patients also may need oxygen and intravenous (IV) fluids.

The illness can be treated with tetracyclines (doxycycline is the preferred treatment), chloramphenicol, macrolides or fluoroquinolones.

The bacterium that causes typhoid fever may be spread through poor hygiene habits and public sanitation conditions, and sometimes also by flying insects feeding on feces. Public education campaigns encouraging people to wash their hands after defecating and before handling food are an important component in controlling spread of the disease. According to statistics from the United States Centers for Disease Control and Prevention (CDC), the chlorination of drinking water has led to dramatic decreases in the transmission of typhoid fever in the United States.

Severe disease is more common in babies and young children, and in contrast to many other infections, it is more common in children who are relatively well nourished. Other risk factors for severe disease include female sex, high body mass index, and viral load. While each serotype can cause the full spectrum of disease, virus strain is a risk factor. Infection with one serotype is thought to produce lifelong immunity to that type, but only short-term protection against the other three. The risk of severe disease from secondary infection increases if someone previously exposed to serotype DENV-1 contracts serotype DENV-2 or DENV-3, or if someone previously exposed to DENV-3 acquires DENV-2. Dengue can be life-threatening in people with chronic diseases such as diabetes and asthma.

Polymorphisms (normal variations) in particular genes have been linked with an increased risk of severe dengue complications. Examples include the genes coding for the proteins known as TNFα, mannan-binding lectin, CTLA4, TGFβ, DC-SIGN, PLCE1, and particular forms of human leukocyte antigen from gene variations of HLA-B. A common genetic abnormality, especially in Africans, known as glucose-6-phosphate dehydrogenase deficiency, appears to increase the risk. Polymorphisms in the genes for the vitamin D receptor and FcγR seem to offer protection against severe disease in secondary dengue infection.

Pappataci fever is prevalent in the subtropical zone of the Eastern Hemisphere between 20°N and 45°N, particularly in Southern Europe, North Africa, the Balkans, Eastern Mediterranean, Iraq, Iran, Pakistan, Afghanistan and India.

The disease is transmitted by the bites of phlebotomine sandflies of the Genus "Phlebotomus", in particular, "Phlebotomus papatasi", "Phlebotomus perniciosus" and "Phlebotomus perfiliewi". The sandfly becomes infected when biting an infected human in the period between 48 hours before the onset of fever and 24 hours after the end of the fever, and remains infected for its lifetime. Besides this «horizontal» virus transmission from man to sandfly, the virus can be transmitted in insects transovarially, from an infected female sandfly to its offspring.

Pappataci fever is seldom recognised in endemic populations because it is mixed with other febrile illnesses of childhood, but it is more well-known among immigrants and military personnel from non-endemic regions.

Tetracycline-group antibiotics (doxycycline, tetracycline) are commonly used. Chloramphenicol is an alternative medication recommended under circumstances that render use of tetracycline derivates undesirable, such as severe liver malfunction, kidney deficiency, in children under nine years and in pregnant women. The drug is administered for seven to ten days.

The treatment for bacillary angiomatosis is erythromycin given for three to four months.

Prevention of sandfly bites, and control of sandflies and their breeding grounds with insecticides are the principal methods for prevention. Mosquito nets may not be sufficient to prevent sandfly bites.

Those dwelling in urban areas (which typically experience rodent problems) have a higher risk of contracting Rickettsialpox.

"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.