A brief descriptive summary of relapsing fever.

1. Relapsing fever

2. outline
• Introduction
• Etiology
• Transmission
• Clinical signs
• Diagnosis
• Treatment
• Prevention and control

3. INTRODUCTION
• Relapsing fever is a bacterial infection caused by several species of spirochete
bacteria in the Borrelia family. It is characterized by repeated episodes of fever.
• Vector borne
• There are two major forms of relapsing fever:
• Tick-borne relapsing fever (TBRF): transmitted by the ornithodoros tick. It occurs
in Africa, Spain, Saudi Arabia, Asia, and certain areas in the western United States
and Canada.
• Louse-borne relapsing fever (LBRF) : transmitted by body lice (Pediculus
humanus). It is most common in Asia, Africa, and Central and South America.

4. Cont.• Epidemiologically LBRF is an epidemic disease with a history from Hippocrates'
times, whereas TBRF is endemic causing sporadic cases since it depends on the
presence of tick reservoirs.
• LBRF is mainly a disease of the developing world. It is currently seen in Ethiopia and
Sudan.
• Famine, war, overcrowding and the movement of refugee groups often results in
LBRF epidemics.
• TBRF carries a low mortality rate. Overall, TBRF carries a mortality rate of less than
2% (in treated patients) to 4-10% (in untreated individuals).
• LBRF carries a higher mortality rate, with a case-fatality rate of 4% (in treated
patients) to 40% (in untreated individuals)

5. ETIOLOGY
• TBRF is caused by 8 or more Borrelia species : Borrelia hermsii, Borrelia
turicatae, Borrelia parkeri, Borrelia duttonii, Borrelia johnsonii, B miyamotoi
• The bacteria species associated with LBRF is Borrelia recurrentis which has a genome
so similar to B. duttonii and B. crocidurae (causes of East and West African tick-
borne relapsing fever)
• Louse-borne relapsing fever is more severe than the tick-borne variety.
• Humans are the sole reservoirs of B recurrentis, while small mammals (eg, pets,
ground and tree squirrels, chipmunks) and reptiles (lizards, snakes, gopher tortoises)
may serve as a reservoir for tickborne Borrelia species.

6. TRANSMISSION
• Transmission of LBRF is confined to the human body louse Pediculus humanus
corporis, and, perhaps, the head louse P. humanus capitis, although the latter has not
been proved.
• 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.
• A single louse can only infect one person.
• Nosocomial infections are possible from contamination by infected blood.
• TBRF is spread through the bite of soft ticks, that live in the nests of squirrels,
chipmunks, and other small animals like chicken & pigs. They feed very quickly and
painlessly

7. CLINICAL SIGNS
• the hallmark of relapsing fever is two or more episodes of high fever, headaches, and
myalgia.
• The fever will “spike” at intervals of approximately 6–8 days, returning to quasi-normal
during the hiatus.
• After a 2- to 14-day incubation period with Borrelia, the patient will display high fever,
chills, fatigue, headache, and malaise.
• Ocular manifestations during acute relapsing fever include photophobia, eye pain, and
conjunctivitis
• If untreated, nausea, vomiting, muscular & joint aches, intestinal pain and damage to
major organs, with a mortality rate of 40%
• Premature birth
• Weakness, unsteady while walking

8. DIAGNOSIS• Blood smear with Wright’s or Giemsa stain or by culture isolation to determine the
cause of the infection
• Other spirochete illnesses (Lyme disease, syphilis, leptospirosis) do not show
spirochetes on blood smear
• Blood antibody tests (usefulness is limited)
• PCR is used for species diagnosis

9. TREATMENT
• one- to two-week-course of Antibiotics including penicillin and tetracycline
are used to treat this condition.
• doxycycline, or erythromycin
• 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 (changing its surface proteins).
•

10. Current status
• TBRF is endemic in Canada (southern portion of British Columbia), Mexico,
Central and South America, central Asia, Africa, the Mediterranean region, and
Russia.
• In 2011, B. recurrentis DNA was found in 23% of head lice in patients with LBRF in
Ethiopia.
• Since 2015, awareness of LBRF in Europe as a re-emerging disease has increased
dramatically by the discovery of this infection in refugees arriving from Africa. (eg
Eritrean refugees in Switzerland)
• In 2016, more cases of LBRF were reported in refugees from East Africa who were
residing in Germany.

11. PREVENTION AND CONTROL
• Wearing clothing that fully covers the arms and legs outdoors
• Insect repellent such as DEET on the skin and clothing also work.
• Tick and lice control in high-risk areas is another important public health measure.
• Rodent control
• Epidemics are controlled by sterilizing clothing to eliminate lice, using
pediculicides and by improving personal hygiene
• High untreated case-fatality (>40%) in some historic epidemics, can be reduced to
less than 5% by antibiotic treatment