Rickettsiosis are diseases caused by Rickettsia bacteria, which multiply within the endothelial cells of blood vessels. They are usually transmitted via arthropod bites like fleas, lice and ticks. The document discusses different types of rickettsiosis like Rocky Mountain spotted fever, typhus and scrub typhus. It also summarizes a study in Rwanda that found Rickettsia prowazekii in blood samples from a typhus outbreak at a prison. Symptoms include fever, rash and neurological or liver involvement. Prevention involves insect repellent and bites while treatment is with doxycycline antibiotics early in the illness.

1. IINNFFEECCTTIIOOUUSS DDIISSEEAASSEESS
DDOOCC 11 (( GGRROOUUPP 33))

2. • Rickettsiosis/rickettsioses are a group of diseases
generally caused by species of Rickettsia.
• They are obligate intracellular gram-negative
coccobacillary
• multiply within eukaryotic cells.

3. INTRODUCTION
• A general characteristic - mammals and
arthropods are natural hosts.
• Rickettsioses are usually transmitted to
humans by arthropods.

4. The rickettsia can be classified into three groups according to
serology
A.Spotted fever biogroup
Rocky Mountain spotted fever
Rickettsialpox
Boutonneuse fever
B.Typhus group
Louse-borne (epidemic) typhus
Brill-Zinsser disease (ie, relapsing
louse-borne typhus)
Murine (endemic or flea-borne)
typhus
C. Scrub typhus biogroup
(Tsutsugamushi disease).

5. QQ ffeevveerr
It is an exception
caused by Coxiella burnetii
recently been removed from the Rickettsiales.
described here for comparison with other
rickettsioses.

6. Rickettsiae multiply within the endothelial cells of small blood
vessels ,
gain access to the bloodstream after skin inoculation.
Focal areas of endothelial proliferation and perivascular
mononuclear cell infiltration cause leakage of intravascular
fluid into tissue space.
Effect on all organs, i.e; skin

7. Systemic effects:
CNS & Heart : damaging host response accompanies vasculitis.
Liver - usually affected with portal triaditis.
Vascular wall destruction consumes platelets, causing
thrombocytopenia.
 Multiple factors
hypoalbuminemia ; eg, renal loss, hepatic involvement.
hyponatremia ; eg, renal loss

8. • Study carried in Eastern province ( Kibungo prison)
• Epidemic Typhus in Kibungo Prison, Eastern Province.
- Blood samples collected from 14 cases revealed Rickettsia
prowazekii in 11 samples (From week 14 of 2013)
- end of week 16 The visit revealed that all suspected cases
have been treated using Doxycycline.
-

9. • Bite by- fleas, lice, mites, and ticks during
feeding.
• scratching crushed arthropods or infectious
feces into the skin.
• Inhaling dust or inoculating conjunctiva with
infectious material.
• transfusion or organ transplantation is rare

10. SSIIGGNNSS && SSYYMMPPTTOOMMSS
• a small, hard, black sore on bite site
• Fever reaches 40-41°C
• Rash on extermities.
• Skin necrosis is rare
• Neurologic findings – seizures, ataxia,
paralysis

11. • These infections are not common and usually
mild they can be difficult to diagnose.
• blood test
• skin biopsy (for example a sample of skin) of
the bite site.

12. PREVENTION
• There is no vaccine available to prevent
infection.
• long sleeved protective clothing –
• an insect repellent

13. • Adequate antibiotic therapy initiated early in
the first week of illness
• Doxycycline is the drug of choice
• Chloramphenicol may be used as an
alternative

14. REFERENCES
• www.medterms.com
• www.medscape.com