Micro - Rickettsial Diseases

Front 1

RICKETTSIAL DISEASES - what causes them?

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A group of arthropod-borne diseases characterized by fever and rash and caused by gram-negative rods of the genus Rickettsia

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RICKETTSIAL DISEASES - who identified it?

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Rickettsia spp.—Named after Dr. Ricketts, who identified ticks as the vector of RMSF in 1905

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RICKETTSIAL DISEASES - what type of bacteria is it?

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Small, obligate intracellular bacteria, gnr

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RICKETTSIAL DISEASES - Why are they difficult to diagnose?

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Difficult to diagnose because they do not grow on artificial media, although they stain in tissues with Giemsa stain

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RICKETTSIAL DISEASES - which one is NOT arthropod-borne?

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All except Coxiella burnetii are arthropod-borne

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RICKETTSIAL DISEASES - where does organism multiply?

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Organisms multiply in insect vector

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RICKETTSIAL DISEASES - 5 groups of diseases:

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5 groups of diseases:
Typhus – Epidemic, Endemic
Spotted Fevers – Rocky Mountain (RMSF), Rickettsialpox, tick typhus group
Scrub Typhus
Q fever
Trench Fev

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RICKETTSIAL DISEASES - Pathologic lesion:

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Pathologic lesion: Vasculitis, often with an eschar at the site of the insect bite or attachment****

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RICKETTSIAL DISEASES - Common clinical findings:

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Common clinical findings:
Fever
Myalgias
Rash (except Q fever)
Arthralgias
Headache
Hepatosplenomegaly
Conjunctivitis
Pharyngitis
Eschar (in Scrub Typhus and Spotted Fevers ex. RMSF)

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RICKETTSIAL DISEASES - Diagnosis

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Diagnosis: Serologic tests most useful****
Specific anti-rickettsial titers (CF, IFA, EIA) – high IgM titre or fourfold rise in paired sera*****
Weil-Felix Tests (antibodies that cross-react with Proteus OX19, OX2, OXK)
Isolation by culture difficult and hazardous

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RICKETTSIAL DISEASES - Diagnosis - which test is most useful?

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: Serologic tests most useful

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RICKETTSIAL DISEASES - Diagnosis - What are the Specific anti-rickettsial titers ?

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Specific anti-rickettsial titers (CF, IFA, EIA) – high IgM titre or fourfold rise in paired sera

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RICKETTSIAL DISEASES - Diagnosis -Weil-Felix Tests

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Weil-Felix Tests (antibodies that cross-react with Proteus OX19, OX2, OXK)

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RICKETTSIAL DISEASES - Diagnosis -Isolation by culture is ___________

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Isolation by culture difficult and hazardous

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Specific antimicrobial therapy:

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Specific antimicrobial therapy: Tetracycline or chloramphenicol

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EPIDEMIC LOUSE-BORNE TYPHUS - Etiology

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Etiology: Rickettsia prowazekii

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EPIDEMIC LOUSE-BORNE TYPHUS - Epi

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Epidemiology: Disease associated with wars, famines, large migrations; esp. in COOLER HIGHLANDS of developing countries (Ethiopia, Uganda, Rwanda, Mexico, Guatemala, Peru, Bolivia)

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EPIDEMIC LOUSE-BORNE TYPHUS - Transmission

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Transmission: Body louse (Pediculus humanis corporis)

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EPIDEMIC LOUSE-BORNE TYPHUS - Pathogenesis

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Lice become infected sucking blood from infected person, and
3-5 days later pass Rickettsiae in their feces.
Humans become infected rubbing louse feces into bite wound.
This is the ONLY rickettsial disease causing illness in the vector (infected lice die in 1-3 weeks)

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EPIDEMIC LOUSE-BORNE TYPHUS - Clinical Findings:

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Clinical Findings:

Average 11 day incubation period

Primary disease is generally SEVERE

ABRUPT ONSET with headache, fever, flushing, vomiting, hypotension; Lice are usually present

NO ESCHAR!!

Rash starts 5-9 days after onset;
macular or maculopapular
starting CENTRALLY and SPARING FACE, PALMS, AND SOLES
may become purpuric or confluent

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EPIDEMIC LOUSE-BORNE TYPHUS - incubation period

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Average 11 day incubation period

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EPIDEMIC LOUSE-BORNE TYPHUS - Primary disease is generally _____

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Primary disease is generally severe

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EPIDEMIC LOUSE-BORNE TYPHUS Si/Sx

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Abrupt onset with headache, fever, flushing, vomiting, hypotension; Lice are usually present

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EPIDEMIC LOUSE-BORNE TYPHUS - Eschar?

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NO eschar

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EPIDEMIC LOUSE-BORNE TYPHUS - Describe Rash

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Rash starts 5-9 days after onset; macular or maculopapular, starting centrally and sparing face, palms, and soles; may become purpuric or confluent

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EPIDEMIC LOUSE-BORNE TYPHUS - Clinical findings:

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Clinical findings:

Critical period in 2nd and 3rd week
Meningoencephalitis common****; delirium and coma, high fevers, pneumonia

Mortality 8-40% if untreated****

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Brill Zinsser Disease:

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EPIDEMIC LOUSE-BORNE TYPHUS

Relapses months or years later;
Same symptoms as primary disease, but milder

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EPIDEMIC LOUSE-BORNE TYPHUS - Diagnosis

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Diagnosis: As above; + IgM in primary disease, mostly IgG in Brill-Zinsser Disease

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EPIDEMIC LOUSE-BORNE TYPHUS - Treatment

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Specific antimicrobial therapy: Tetracycline or chloramphenicol

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EPIDEMIC LOUSE-BORNE TYPHUS - Epidemic Control:

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Epidemic Control: Elimination of lice (10% DDT); include body, bedding, clothing, living quarters

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - Etiology

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Etiology: Rickettsia typhi

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - Epidemiology

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Epidemiology: Mostly in WARM ZONES where people and rats live in the same house; esp. in port cities (harbors) and granaries; less severe and less common than epidemic typhus

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - Transmission

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Transmission: Rat fleas (Xenopsylla cheopsis) transmit organisms between rats and from rats to humans; humans infected from flea feces through bites, cuts, inhalation, conjunctivae

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - Clinical findings

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Clinical findings: Similar to epidemic typhus, but milder; less prominent rash & shorter duration,

ABRUPT ONSET with headache, fever, flushing, vomiting, hypotension; Lice are usually present

NO ESCHAR!!

Rash starts 5-9 days after onset;
macular or maculopapular
starting CENTRALLY and SPARING FACE, PALMS, AND SOLES
may become purpuric or confluent

Outcome much better than in epidemic typhus (2% mortality in untreated patients),

NO relapsing form

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - host and resovior

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Infection maintained in nature rat-flea-rat

Human infection is incidental

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - Diagnosis

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Diagnosis: Serologic tests most useful
Specific anti-rickettsial titers (CF, IFA, EIA) – high IgM titre or fourfold rise in paired sera
Weil-Felix Tests (antibodies that cross-react with Proteus OX19, OX2, OXK)
Isolation by culture difficult and hazardous

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS - Treatment

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Specific antimicrobial therapy: Tetracycline or chloramphenicol

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ENDEMIC (MURINE, FLEA-BORNE) TYPHUS -Control

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Control: DDT application to rat infested areas, followed by rat control (insect control first , or insects may transfer to other hosts and continue spread)

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SCRUB TYHPUS (TSUTSUGAMUSHI FEVER; MITE-BORNE TYPHUS) - Etiology

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Etiology: R. tsutsugamushi

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SCRUB TYHPUS (TSUTSUGAMUSHI FEVER; MITE-BORNE TYPHUS) - Epidemiology

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Epidemiology: Endemic in rural Asia (east and south) and Western Pacific; Does NOT occur in other continents
FOCAL distribution in these regions (esp. cleared forest with scrub vegetation)
Outbreaks often due to ECOLOGICAL ALTERATIONS (landslides, fires, monsoons) or man-made alterations (jungle clearing, road building)

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SCRUB TYHPUS (TSUTSUGAMUSHI FEVER; MITE-BORNE TYPHUS) - Transmission

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Transmission:
Principally a zoonosis maintained in MITES and their RODENT HOSTS

Humans develop INCIDENTALLY infection by the bite of infected MITES (chiggers)

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SCRUB TYPHUS - CLINICAL FEATURES

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Broad spectrum from inapparent to mild to fatal
Incubation period 8-12 days with fever, headaches, myalgias
Rash in second week in 60%; Pink, maculopapular, trunk to extremities, INCLUDING PALMS AND SOLES (papule--> pustule --> ulcer with black crust and red margin)

70% of cases with ONE OR MORE ESCHARS, often with associated regional lymphadenitis
Generalized lymphadenitis; eye findings (pain, conjunctivitis), pneumonitis, hepatosplenomegaly
Second week complications may occur as in epidemic typhus (meningeal, pneumonia)

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SCRUB TYPHUS - Diagnosis and Treatment

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Diagnosis and Treatment: As above;

Scrub typhus is the ONLY RICKETSIOSIS to CROSS-REACT with OXK antigen

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SCRUB TYPHUS - Control

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Control: Area control of mites with insecticide, followed by rodent control

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Which rickettsiosis cross-reacts with OXK antigen?

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SCRUB TYPHUS

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SPOTTED FEVERS

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A group of related febrile illnesses caused by TICK bites

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SPOTTED FEVERS - Etiology:

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Etiology:
R. rickettsii - Rocky Mountain Spotted Fever (RMSF) -TICK
R. conorii - Tick typhus group (Boutonneuse fever, Kenya tick typhus, South African tick fever) - TICK
R. akari - Rickettsialpox - MITE!!

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SPOTTED FEVERS
Epidemiology:
RMSF

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North America, Mexico and Central America, northern South America

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SPOTTED FEVERS
Epidemiology:
Tick typhus group

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Mediterranean, Black, and Caspian Sea coasts; East Central Africa; Thailand and Malaysia

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SPOTTED FEVERS
Epidemiology:
Rickettsialpox

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Patchy distribution, esp. west, central, and southern Africa; parts of S. E. Asia

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SPOTTED FEVERS
Transmission:
RMSF and Tick Typhus:

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RMSF and Tick Typhus: Tick bites (various species)

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SPOTTED FEVERS
Transmission:
Rickettsialpox:

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Rickettsialpox: Mite bite

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***SPOTTED FEVERS
Clinical findings:
RMSF frequently ___, whereas others are ___

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RMSF frequently severe, whereas others are mild

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***SPOTTED FEVERS
Clinical findings:
Eschars present in ___, NOT in ___

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Eschars present in tick typhus group, NOT in RMSF

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***SPOTTED FEVERS
Clinical findings:
General symptoms similar to ___, but rash is ____);

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General symptoms similar to epidemic typhus, but rash is very prominent (pink red, petechialecchymoses that *****mimics meningiococcemia*******);

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***SPOTTED FEVERS
Clinical findings:
___is the only one with a rash starting on the___

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RMSF is the only one with a rash starting on the distal extremities

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***SPOTTED FEVERS
Clinical findings:
Complications of RMSF similar to ___, but with ______

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Complications of RMSF similar to epidemic typhus, but with prominent edema, capillary leak, shock, DIC

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SPOTTED FEVERS
Rickettsialpox:

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Mild febrile illness, prominent ESCHAR, regional lymphadenitis, mild rash

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Diagnosis of Spotted Fevers:

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Specific serologies;

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Diagnosis of Spotted Fevers:
___ does NOT react in the Weil Felix tests

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Rickettsialpox does NOT react in the Weil Felix tests

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Treatment of Spotted Fevers:

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Tetracycline or chloramphenicol

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Control of Spotted Fevers:

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Control of Spotted Fevers: Tick repellants, control ticks on domestic animals

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The “Exceptional Rickettsiosis”

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Q FEVER

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Q Fever
Etiology:

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Coxiella burneti

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Q Fever
Epi:

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Endemic in areas where domestic animals are raised (cattle, sheep, goats);

Found in the U.S., Africa, Europe

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Q Fever
Transmission:

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USUALLY NOT INSECT-BORNE; ***\
human disease acquired by ***inhalation of aerosols**** from tissues & body fluids of infected animals (incl. milk)
Maintained in nature in domestic & wild animals via infected ticks, lice, and fleas; insect-borne transmission to humans rare

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Q FEVER
Clinical findings:

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RASH IS RARE (5-10%); ***
Most infections are mild with fever, headache,
myalgias, pharyngitis
***Interstitial pneumonia*** (20-50%), hepatomegaly and hepatitis (20-40%), chronic endocarditis occurs rarely

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Q FEVER
Diagnosis

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Specific serologies (no Weil-Felix reaction)

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Q FEVER
txt

Back 69

tetra or chloramphenicol

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Q FEVER
control

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Control: Disposal of livestock waste;

Inactivated vaccine for livestock and humans at risk

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TRENCH FEVER
etiology

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Etiology: Bartonella (Rochalimaea) quintana
Uncommon louse-borne febrile illness described in Eastern Europe and North Africa
Epidemics in World Wars I and II associated with poor hygiene

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TRENCH FEVER
transmission

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Transmission: Like epidemic typhus, disease is acquired by inoculation of louse feces through skin

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TRENCH FEVER
reservoir

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Humans are the primary reservoir, and infection may persist for years

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TRENCH FEVER
clinical features

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Clinical features: Fever, conjunctivitis, splenomegaly, transient rash; may relapse over many years (like Brill-Zinsser Disease)

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TRENCH FEVER
diagnosis

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Specific serologies (no Weil-Felix reaction)

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TRENCH FEVER
txt and control

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tetra or chlorampenicol

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which rickettsial causes vector death?

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epidemic typhus - R. proweskii

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Louse-borne

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epidemic typhus - R. proweskii
trench fever - Bartonella

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Mite borne

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scrub typhus - Tsu Tsu gamushi
spotted fever - R. akari - rickettsialpox

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Rat- FLEA borne

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endemic typhus - R. typhi

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Tick-borne

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Spotted fever - R. rickettsii - RMSF
Spotted fever - R. conorii - tick typhs group

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Palms and Soles

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RMSF - ONLY ONE TO START THERE
scrub typhus - tsu tsu

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Not insect borne

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q-fever - coxiella burnetii

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has relasping fever

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epidemic typhus - R. proweskii
trench fever - Bartonella

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NO weil-felix rxn

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Spotted Fever - rickettsial pox - R. akari
Trench Fever - bartonella
Q-Fever - Coxiella burnetii

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What are paired sera, and when are they needed?

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Serum (sera is plural) is the liquid portion left after the cells are removed from whole blood. Serum contains antibodies. Paired sera are required when the only test available to detect a certain disease can only detect specific IgG or total antibody. Sera drawn from a patient 14-21 days apart are tested simultaneously. If there is a significant rise in titer (amount of antibody), significant decrease in titer, or seroconversion, the patient is considered to have a current infection. If a test is available to test specifically for IgM, then only a single serum is required.