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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.
The illness can be treated with tetracyclines (doxycycline is the preferred treatment), chloramphenicol, macrolides or fluoroquinolones.
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.
Appropriate antibiotic treatment should be started immediately when there is a suspicion of Rocky Mountain spotted fever on the basis of clinical and epidemiological findings. Treatment should not be delayed until laboratory confirmation is obtained. In fact, failure to respond to a tetracycline argues against a diagnosis of Rocky Mountain spotted fever. Severely ill patients may require longer periods before their fever resolves, especially if they have experienced damage to multiple organ systems. Preventive therapy in healthy patients who have had recent tick bites is not recommended and may, in fact, only delay the onset of disease.
Doxycycline (a tetracycline) (for adults at 100 milligrams every 12 hours, or for children under at 4 mg/kg of body weight per day in two divided doses) is the drug of choice for patients with Rocky Mountain spotted fever, being one of the only instances doxycycline is used in children. Treatment should be continued for at least three days after the fever subsides, and until there is unequivocal evidence of clinical improvement. This will be generally for a minimum time of five to ten days. Severe or complicated outbreaks may require longer treatment courses. Doxycycline/ tetracycline is also the preferred drug for patients with ehrlichiosis, another tick-transmitted infection with signs and symptoms that may resemble those of Rocky Mountain spotted fever.
Chloramphenicol is an alternative drug that can be used to treat Rocky Mountain spotted fever, specifically in pregnancy. However, this drug may be associated with a wide range of side effects, and careful monitoring of blood levels can be required.
African tick bite fever is usually mild, and most patients do not need more than at-home treatment with antibiotics for their illness. However, because so few patients with this infection visit a doctor, the best antibiotic choice, dose and length of treatment are not well known. Typically doctors treat this disease with antibiotics that have been used effectively for the treatment of other diseases caused by bacteria of similar species, such as Rocky Mountain Spotted Fever.
For mild cases, people are usually treated with one of the following:
- doxycycline
- chloramphenicol
- ciprofloxacin
If a person has more severe symptoms, like a high fever or serious headache, the infection can be treated with doxycycline for a longer amount of time. Pregnant women should not use doxycycline or ciprofloxacin as both antibiotics can cause problems in fetuses. Josamycin has been used effectively for treatment of pregnant women with other rickettsial diseases, but it is unclear if it has a role in the treatment of ATBF.
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
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.
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
Doxycycline has been used in the treatment of rickettsial infection.
The disease develops from March to September, with the highest infections occurring in June. The disease is found almost exclusively in the western United States and Canada, mostly in high mountain areas such as Colorado and Idaho. The CTFV was first isolated from human blood in 1944.
No specific treatment for CTF is yet available. The first action is make sure the tick is fully removed from the skin, then acetaminophen and analgesics can be used to help relieve the fever and pain. Aspirin is not recommended for children, as it has been linked to Reye’s syndrome in some viral illnesses. Salicylates should not be used because of thrombocytopenia, and the rare occurrence of bleeding disorders. People who suspect they have been bitten by a tick or are starting to show signs of CTF should contact their physicians immediately.
Prevention depends on control of and protection from the bites of the mosquito that transmits it. The World Health Organization recommends an Integrated Vector Control program consisting of five elements:
1. Advocacy, social mobilization and legislation to ensure that public health bodies and communities are strengthened;
2. Collaboration between the health and other sectors (public and private);
3. An integrated approach to disease control to maximize use of resources;
4. Evidence-based decision making to ensure any interventions are targeted appropriately; and
5. Capacity-building to ensure an adequate response to the local situation.
The primary method of controlling "A. aegypti" is by eliminating its habitats. This is done by getting rid of open sources of water, or if this is not possible, by adding insecticides or biological control agents to these areas. Generalized spraying with organophosphate or pyrethroid insecticides, while sometimes done, is not thought to be effective. Reducing open collections of water through environmental modification is the preferred method of control, given the concerns of negative health effects from insecticides and greater logistical difficulties with control agents. People can prevent mosquito bites by wearing clothing that fully covers the skin, using mosquito netting while resting, and/or the application of insect repellent (DEET being the most effective). However, these methods appear not to be sufficiently effective, as the frequency of outbreaks appears to be increasing in some areas, probably due to urbanization increasing the habitat of "A. aegypti". The range of the disease appears to be expanding possibly due to climate change.
Tick control is the most effective method of prevention, but tetracycline at a lower dose can be given daily for 200 days during the tick season in endemic regions.
Those dwelling in urban areas (which typically experience rodent problems) have a higher risk of contracting Rickettsialpox.
Rickettsialpox is generally mild and resolves within 2–3 weeks if untreated. There are no known deaths resulting from the disease.
In 2016 a partially effective vaccine for dengue fever became commercially available in the Philippines and Indonesia. It has also been approved for use by Mexico, Brazil, El Salvador, Costa Rica, and Paraguay. In Indonesia it costs about US$207 for the recommended three doses.
The vaccine is produced by Sanofi and goes by the brand name Dengvaxia. It is based on a weakened combination of the yellow fever virus and each of the four dengue serotypes. Two studies of a vaccine found it was 60% effective and prevented more than 80 to 90% of severe cases. This is less than wished for by some. In 2017 the manufacturer recommended that the vaccine only be used in people who have previously had a dengue infection as otherwise there was evidence it may worsen subsequent infections.
There are ongoing programs working on a dengue vaccine to cover all four serotypes. Now that there is a fifth serotype this will need to be factored in. One of the concerns is that a vaccine could increase the risk of severe disease through antibody-dependent enhancement (ADE). The ideal vaccine is safe, effective after one or two injections, covers all serotypes, does not contribute to ADE, is easily transported and stored, and is both affordable and cost-effective.
Supportive care must be provided to animals that have clinical signs. Subcutaneous or intravenous fluids are given to dehydrated animals, and severely anemic dogs may require a blood transfusion. Treatment for ehrlichiosis involves the use of antibiotics such as tetracycline or doxycycline for a period of at least six to eight weeks; response to the drugs may take one month. Treatment with macrolide antibiotics like clarithromycin and azithromycin is being studied. In addition, steroids may be indicated in severe cases in which the level of platelets is so low that the condition is life-threatening.
Boutonneuse fever (also called Mediterranean spotted fever, fièvre boutonneuse, Kenya tick typhus, Indian tick typhus, Marseilles fever, or African tick-bite fever) is a fever as a result of a rickettsial infection caused by the bacterium "Rickettsia conorii" and transmitted by the dog tick "Rhipicephalus sanguineus". Boutonneuse fever can be seen in many places around the world, although it is endemic in countries surrounding the Mediterranean Sea. This disease was first described in Tunisia in 1910 by Conor and Bruch and was named "boutonneuse" (French for "spotty") due to its papular skin rash characteristics.
No vaccine is licensed for use in the U.S. Infection with either of these bacteria results in nonspecific symptoms and can be either acute or chronic, impeding rapid diagnosis. The lack of a vaccine for either bacterium also makes them potential candidates for bioweaponization. Together with their high rate of infectivity by aerosols and resistance to many common antibiotics, both bacteria have been classified as category B priority pathogens by the US NIH and US CDC, which has spurred a dramatic increase in interest in these microorganisms. Attempts have been made to develop vaccines for these infections, which would not only benefit military personnel, a group most likely to be targeted in an intentional release, but also individuals who may come in contact with glanders-infected animals or live in areas where melioidosis is endemic.
There is a re-emergence of mosquito vector viruses (arthropod-borne viruses) called arboviruses carried by the "Aedes aegypti" mosquito. Examples are the Zika virus, chikungunya virus, yellow fever and dengue fever. The re-emergence of the viruses has been at a faster rate, and over a wider geographic area, than in the past. The rapid re-emergence is due to expanding global transportation networks, the mosquito's increasing ability to adapt to urban settings, the disruption of traditional land use and the inability to control expanding mosquito populations. Like malaria, other arboviruses do not have a vaccine. The only exception is yellow fever. Prevention is focused on reducing the adult mosquito populations, controlling mosquito larvae and protecting individuals from mosquito bites. Depending on the mosquito vector, and the affected community, a variety of prevention methods may be deployed at one time.
There is a vaccine for yellow fever which was developed in the 1930s, the yellow 17D vaccine, and it is still in use today. The initial yellow fever vaccination provides lifelong protection for most people and provides immunity within 30 days of the vaccine. Reactions to the yellow fever vaccine have included mild headache and fever, and muscle aches. There are rare cases of individuals presenting with symptoms that mirror the disease itself. The risk of complications from the vaccine are greater for individuals over 60 years of age. In addition, the vaccine is not usually administered to babies under nine months of age, pregnant women, people with allergies to egg protein, and individuals living with AIDS/HIV. The World Health Organization (WHO) reports that 105 million people have been vaccinated for yellow fever in West Africa from 2000 to 2015.
Queensland tick typhus (or Australian tick typhus or (Rickettsial) spotted fever) is a condition caused by a bacterium "Rickettsia australis".
It is transmitted by "Ixodes holocyclus" and "Ixodes tasmani".
Rickettsioses can be divided into a spotted fever group (SPG) and typhus group (TG).
In the past, rickettsioses were considered to be caused by species of Rickettsia. However, scrub typhus is still considered a rickettsiosis, even though the causative organism has been reclassified from "Rickettsia tsutsugamushi" to "Orientia tsutsugamushi".
Examples of rickettsioses include typhus, both endemic and epidemic, Rocky Mountain spotted fever, and Rickettsialpox.
Organisms involved include Rickettsia parkeri.
Many new causative organisms have been identified in the last few decades.
Most are in the genus Rickettsia, but scrub typhus is in the genus Orientia.
In 2012, the World Health Organization estimated that vaccination prevents 2.5 million deaths each year. If there is 100% immunization, and 100% efficacy of the vaccines, one out of seven deaths among young children could be prevented, mostly in developing countries, making this an important global health issue. Four diseases were responsible for 98% of vaccine-preventable deaths: measles, "Haemophilus influenzae" serotype b, pertussis, and neonatal tetanus.
The Immunization Surveillance, Assessment and Monitoring program of the WHO monitors and assesses the safety and effectiveness of programs and vaccines at reducing illness and deaths from diseases that could be prevented by vaccines.
Vaccine-preventable deaths are usually caused by a failure to obtain the vaccine in a timely manner. This may be due to financial constraints or to lack of access to the vaccine. A vaccine that is generally recommended may be medically inappropriate for a small number of people due to severe allergies or a damaged immune system. In addition, a vaccine against a given disease may not be recommended for general use in a given country, or may be recommended only to certain populations, such as young children or older adults. Every country makes its own vaccination recommendations, based on the diseases that are common in its area and its healthcare priorities. If a vaccine-preventable disease is uncommon in a country, then residents of that country are unlikely to receive a vaccine against it. For example, residents of Canada and the United States do not routinely receive vaccines against yellow fever, which leaves them vulnerable to infection if travelling to areas where risk of yellow fever is highest (endemic or transitional regions).
Glanders (from Middle English ' or Old French ', both meaning glands; , ; also known as "equinia", "farcy", and "malleus") is an infectious disease that occurs primarily in horses, mules, and donkeys. It can be contracted by other animals, such as dogs, cats, goats and humans. It is caused by infection with the bacterium "Burkholderia mallei", usually by ingestion of contaminated feed or water. Signs of glanders include the formation of nodular lesions in the lungs and ulceration of the mucous membranes in the upper respiratory tract. The acute form results in coughing, fever, and the release of an infectious nasal discharge, followed by septicaemia and death within days. In the chronic form, nasal and subcutaneous nodules develop, eventually ulcerating. Death can occur within months, while survivors act as carriers.
Glanders is endemic in Africa, Asia, the Middle East, and Central and South America. It has been eradicated from North America, Australia, and most of Europe through surveillance and destruction of affected animals, and import restrictions.
"B. mallei" is able to infect humans, so is classed as a zoonotic agent. Transmission occurs by direct contact with infected animals and entry is through skin abrasions, nasal and oral mucosal surfaces, or by inhalation.
The mallein test is a sensitive and specific clinical test for glanders. Mallein (ATCvet code: ), a protein fraction of the glanders organism ("B. mallei"), is injected intradermopalpebrally or given by eye drop. In infected animals, the eyelid swells markedly in 1 to 2 days.
Glanders has not been reported in the United States since 1945, except in 2000 when an American lab researcher suffered from accidental exposure. It is a notifiable disease in the UK, although it has not been reported there since 1928.