Relapsing fever

Relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus Borrelia,[1] which is transmitted through the bites of lice or soft-bodied ticks (genus Ornithodoros).[2]

Relapsing fever
SpecialtyInfectious disease 

Signs and symptoms

Most people who are infected develop sickness between 5 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 2 to 9 days, then disappear. This cycle may continue for several weeks if the person is not treated.[3]

Causes

Louse-borne relapsing fever

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.[4] 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.[5] 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.

Tick-borne relapsing fever

Tick-borne relapsing fever is found primarily in Africa, Spain, Saudi Arabia, Asia, and certain areas of Canada and the western United States. Other relapsing infections are acquired from other Borrelia species, which can be spread from rodents, and serve as a reservoir for the infection, by a tick vector.

B. hermsii and B. recurrentis cause very similar diseases. However, one or two relapses are common with the disease associated with B. hermsii, which is also the most common cause of relapsing disease in the United States. (Three or four relapses are common with the disease caused by B. recurrentis, which has longer febrile and afebrile intervals and a longer incubation period than B. hermsii.)

Diagnosis

The diagnosis of relapsing fever can be made on blood smear as evidenced by the presence of spirochetes. Other spirochete illnesses (Lyme disease, syphilis, leptospirosis) do not show spirochetes on blood smear. Although considered the gold standard, this method lacks sensitivity and has been replaced by PCR in many settings.[7]

Treatment

Relapsing fever is easily treated with a one- to two-week-course of antibiotics, and most people improve within 24 hours. Complications and death due to relapsing fever are rare.

Tetracycline-class antibiotics are most effective. These can, however, induce a Jarisch–Herxheimer reaction in over half those treated, producing anxiety, diaphoresis, fever, tachycardia and tachypnea with an initial pressor response followed rapidly by hypotension. Recent studies have shown tumor necrosis factor-alpha may be partly responsible for this reaction.

Research

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.

History

Relapsing fever has been described since the days of the ancient Greeks.[8] After an outbreak in Edinburgh in the 1840s, relapsing fever was given its name, but the etiology of the disease was not better understood for a decade.[8] Physician David Livingstone is credited with the first account in 1857 of a malady associated with the bite of soft ticks in Angola and Mozambique.[9] In 1873, Otto Obermeier first described the disease-causing ability and mechanisms of spirochetes, but was unable to reproduce the disease in inoculated test subjects and thereby unable to fulfill Koch's postulates.[8] The disease was not successfully produced in an inoculated subject until 1874.[8] In 1904 and 1905, a series of papers outlined the cause of relapsing fever and its relationship with ticks.[10][11][12][13] Both Joseph Everett Dutton and John Lancelot Todd contracted relapsing fever by performing autopsies while working in the eastern region of the Congo Free State. Dutton died there on February 27, 1905. The cause of tick-borne relapsing fever across central Africa was named Spirillum duttoni.[14] In 1984, it was renamed Borrelia duttoni.[15] The first time relapsing fever was described in North America was in 1915 in Jefferson County, Colorado.[16]

Sir William MacArthur suggested that relapsing fever was the cause of the yellow plague, variously called pestis flava, pestis ictericia, buidhe chonaill, or cron chonnaill, which struck early Medieval Britain and Ireland, and of epidemics which struck modern Ireland in the famine.[17][18] This is consistent with the description of the symptoms suffered by King Maelgwn of Gwynedd as recorded in words attributed to Taliesin and with the "great mortality in Britain" in 548 CE noted in the Annales Cambriae.

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See also

References
  1. Schwan T (1996). "Ticks and Borrelia: model systems for investigating pathogen-arthropod interactions". Infect Agents Dis. 5 (3): 167–81. PMID 8805079.
  2. Schwan T, Piesman J; Piesman (2002). "Vector interactions and molecular adaptations of Lyme disease and relapsing fever spirochetes associated with transmission by ticks". Emerg Infect Dis. 8 (2): 115–21. doi:10.3201/eid0802.010198. PMC 2732444. PMID 11897061.
  3. Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 432–4. ISBN 978-0-8385-8529-0.CS1 maint: extra text: authors list (link)
  4. Fournier, Pierre-Edouard. "Human Pathogens in Body and Head Lice". PMID 12498677. Retrieved October 17, 2010. Cite journal requires |journal= (help)
  5. Cutler S (2006). "Possibilities for relapsing fever reemergence". Emerg Infect Dis. 12 (3): 369–74. doi:10.3201/eid1203.050899. PMC 3291445. PMID 16704771.
  6. McNeil, Donald (19 September 2011). "New Tick-Borne Disease Is Discovered". The New York Times. pp. D6. Retrieved 20 September 2011.
  7. Fotso Fotso A, Drancourt M (2015). "Laboratory Diagnosis of Tick-Borne African Relapsing Fevers: Latest Developments". Frontiers in Public Health. 3: 254. doi:10.3389/fpubh.2015.00254. PMC 4641162. PMID 26618151.
  8. Cutler, S.J. (April 2010). "Relapsing fever – a forgotten disease revealed". Journal of Applied Microbiology. 108 (4): 1115–1122. doi:10.1111/j.1365-2672.2009.04598.x. ISSN 1365-2672. PMID 19886891.
  9. Livingstone D (1857) Missionary travels and researches in South Africa. London: John Murray
  10. Cook AR (1904). "Relapsing fever in Uganda". J Trop Med Hyg. 7: 24–26.
  11. Ross, P. H.; Milne, A. D. (1904). "Tick Fever". British Medical Journal. 2 (2291): 1453–4. doi:10.1136/bmj.2.2291.1453. PMC 2355890. PMID 20761784.
  12. Dutton JE, Todd JL (1905). "The nature of human tick-fever in the eastern part of the Congo Free State with notes on the distribution and bionomics of the tick". Liverpool School Trop Med Mem. 17: 1–18.
  13. Wellman FC (1905). "Case of relapsing fever, with remarks on its occurrence in the tropics and its relation to "tick fever"". J Trop Med. 8: 97–99.
  14. Novy, F. G.; Knapp, R. E. (1906). "Studies on Spirillum obermeieri and related organisms". Journal of Infectious Diseases. 3 (3): 291–393. doi:10.1093/infdis/3.3.291. hdl:2027/hvd.32044106407547. JSTOR 30071844.
  15. Kelly RT (1984) "Genus IV. Borrelia Swellengrebel 1907" in Krieg NR (ed.) Bergey's Manual of Systematic Bacteriology. Baltimore: Williams & Wilkins
  16. Davis, Gordon E. (1940-01-01). "Ticks and Relapsing Fever in the United States". Public Health Reports. 55 (51): 2347–2351. doi:10.2307/4583554. JSTOR 4583554.
  17. Bonser, Wilfrid; MacArthur, Wm (1944). "Epidemics during the Anglo-Saxon period, with appendix: Famine fevers in England and Ireland". Journal of the British Archaeological Association. 9: 48–71. doi:10.1080/00681288.1944.11894687.
  18. MacArthur, W (1947). "Famine fevers in England and Ireland". Postgraduate Medical Journal. 23 (260): 283–6. doi:10.1136/pgmj.23.260.283. PMC 2529527. PMID 20248471.
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