Relapsing fever notes
Download as PPTX, PDF17 likes8,738 views
Relapsing fever is an infectious disease caused by Borrelia bacteria and transmitted by body lice or soft ticks. It is characterized by alternating periods of fever and afebrile periods. There are two main types - louse-borne transmitted by body lice and tick-borne transmitted by soft ticks. Symptoms include fever, headaches, and bleeding. Treatment involves antibiotics like doxycycline or erythromycin for 7 days to prevent relapses, though a severe reaction can occur when bacteria are killed rapidly. Control relies on improving housing to remove areas where lice and ticks thrive.
Relapsing fever notes
- 3. Definition • Relapsing fever: An acute, infectious, bacterial (spirochete) disease characterized by alternating febrile periods and non febrile periods. • It is also known as recurrent fever or tick fever.
- 4. Types of Relapsing Fever • There are 2 types of relapsing fever: o Louse-borne relapsing fever o Tick born relapsing fever
- 5. Transmission Louse-borne Relapsing Fever • Louse-borne relapsing fever is transmitted by the human head – Pediculus capitis and the common body louse; Pediculus corporis. • Louse-borne relapsing fever is transmitted from person to person by the human louse. • Both types of relapsing fever are caused by spirochaetes of the genus Borrelia; louse - borne carry Borrelia recurrentis. • The spirochaetes are taken up when the louse feeds on the blood of an infected person. • They then multiply within the body of the louse but are not present in the saliva or coxal fluid. • This louse only infects another person when it is crushed on the body near the bite wound. The organisms are not transmitted to the offspring of the lice. • It tends to occur in epidemics.
- 6. Tick Born Relapsing Fever • Tick born relapsing fever is transmitted by soft ticks called Ornithodorus moubata • Tick-borne relapsing fever is transmitted when the tick sucks blood from an infected person and the spirochaetes are taken up and multiply in the body of the tick • Ticks carry Borrelia duttoni • The spirochetes pass into the ovary of the tick and the offspring of an infected tick are automatically infected without themselves having sucked infectious blood i.e. transovarian or vertical transmission • Ticks remain infectious for the rest of its life • In this way, a house once inhabited by infectious ticks can remain dangerous for many years if no intervention • Within one week after sucking infected blood spirochaetes appear in the tick's salivary glands and in the coxal fluid ready to be transmitted to a new host
- 7. cont... The organisms can either be injected directly when the tick feeds on the host, or they invade the body through intact mucous membrane. (e.g., in laboratory infections: Duttoni, the discoverer of the disease died from it) • In humans, the spirochaetes can cross the placenta from mother to foetus • This may result in abortion, stillbirth, premature delivery or congenital infection in the newborn
- 8. Clinical Features of Relapsing Fever SYMPTOMS Fever Headaches Arthralgia/myalgia Dry cough Epistaxis/gum bleeding SIGNS Temperature Tachycardia Hepatomegaly Splenomegaly Petichea/ Subconjunctival bleeding Jaundice Confusion/Meningism
- 9. Complications ● Congestive heart failure ● Jaundice ● Bleeding diathesis ● Jarish- Herxheimer reaction:
- 10. Natural History • Without treatment, symptoms intensity over a 2- to 7-day period (average 5 days in LBRF and 3 days in TBRF), ending in a spontaneous crisis that coincides with the disappearance of spirochetes from the circulation. • The crisis comprises 2 phases over several hours: o A chill phase, characterised by stiffening of muscles, rising temperature, and hypermetabolism, and a flush phase of falling temperature, profuse perspiration and a decreased effective circulating blood volume o The crisis is followed by a period of exhaustion, sleep, and an uneventful recovery. o In the first week of convalescence, the patient may experience 1 or 2 days of mild fever un-associated with detectable spirochaetemia
- 11. cont... • In untreated patients, spirochaetemia and symptoms may recur after a period of several days or weeks • Only 1 or 2 relapses characteristically occur in untreated patients with LBRF, whereas as many as 10 can occur in untreated patients with TBRF • In most cases, the illness becomes shorter and milder and a febrile intervals longer with each relapse
- 12. Differential Diagnosis of Relapsing Fever • Malaria • Typhoid fever • Tuberculosis • Leptospirosis • Viral haemorrhagic fever • Acute HIV seroconversion • Influenza
- 13. Management of Relapsing Fever Diagnosis • The clinical picture may be so similar to malaria that only a blood smear can differentiate the two. • Microscopic examination of a thick blood smear stained with Leishman or Giemsa, as is done for malaria, is useful in diagnosis. • Malaria as a differential diagnosis can also be excluded at the same time. • Differentiation between the two types of relapsing fever is not possible by microscopy.
- 14. Treatment • The organisms causing relapsing fever are very sensitive to antibiotics. • LBRF is usually treated with single dose therapy while TBRF is treated with a 7- day course of antibiotics. • Since due to limited resources of differentiating the two organisms a 7-day course of antibiotics should be given for both. • Pregnant women and young children 8 years old should be treated with penicillin or erythromycin, given the potential adverse effects of tetracycline in these populations.
- 15. Drug and Dosage Erythromycin 500mg. 6 hourly Tetracycline 500mg. 6 hourly Doxycycline 100mg. BD. 12 hourly Chloramphenicol 500mg. 6 hourly Procaine penicillin G 600, 000 iv per day
- 16. Jarisch-Herxheimer Reaction • Some deaths occur after starting treatment as a result of a severe Jarisch-Herxheimer reaction. • The antibiotic suddenly kills a large number of spirochaetes which release ‘toxins’ into the circulation causing the patient to collapse. • This reaction is characterised by rapid breathing, chills and a fall in blood pressure. • Patients must be nursed flat, given adequate fluids and be confined to bed for at least 24 hours. • This reaction tends to be more pronounced with the use of rapidly acting or large doses of antibiotics. • To prevent the Jarisch-Herxheimer reaction one may use prednisolone 10-20 mg 8- hourly for 3 days then start treatment for LBRF or TBRF after 24 hours (but use steroids carefully)
- 17. Prevention and control of Relapsing Fever • The best way to control the disease is to improve housing conditions especially filling of the cracks in the walls. • The use of corrugated-iron sheets for roofing would eliminate this problem but not everyone can afford them. • It is hoped, however, that as the standards of living improve, more people will be able to afford better housing and the disease will be eliminated. • Insecticides can be used to kill ticks. • Gammexane (Gammatox plus) is recommended. • One kilogram of gammexane is enough to make 40 litres of solution which can then be sprayed or applied on the floor and walls and in cracks.
- 18. cont... • Control of tick fever can also be achieved by reducing exposure to the infection. • People who sleep on the floor have the greatest risk of infection. • The use of beds should therefore be encouraged. • Mass treatment of patients is not useful as the important reservoir is the tick; once infected, a tick is able to produce offspring which are also infectious.
- 19. Never kills your inborn TALENT!