Rickettsia, Spirochetes (borrelia, leptospirosis, syphilis), Q fever Flashcards
What are the borrelia species and what do they cause?
Lime disease - Borrelia burgdorferi.
Relapsing fever
- Tick-borne - Borrelia hermsii, Borrelia turicatae, Borrelia parkeri
-Louse borne - Borrelia recurrentis
Name of louse in louse bourne relapsing fever? Organism? Basic life cycle
Pediculus humanus
[or P Capitis]
borrelia recurrentis
Louse bites human - gets infected with borrelia recurrentis and stays infective for life. When scratch -> crushes louse and then releases borrelia which enters through broken mucus membranes
2 main types of relapsing fever? Which is usually worse with hepatomegaly and jaundice? which has more relapses?
Louse bourne - LBRF
- Jaundice and hepatomegaly
-up to 3 relapses
-fatality rate almost 70% without Rx
Tic bourne - TBRF
- up to 11 relapses
Dx borriela ? rx?
-Blood film with Giemsa/ wright stain
-dark field microscopy [spirochaetes around 10-30um]
PCR best
Abx - Doxy best 5-10 days
ceftriaxone if meningitis
Who gets Jarisch-herxheimer reaction? What is it? rx?
Borriella treated with bacteriocidal abx Eg pencilin / ceflasporins
Life threatening - intense rigors / hyperthermia +/- shock shortly after abx
Rx with meptazinol
Which pathogen specifically in louse bourn relapsing fever?
B recurrentis
What causes louse-bourne typhus?
Rickettsia prowazekki from infected faeces of louse (pediculus humanus) which gets scratched into skin
Louse bourn typhus R prowazekii incubation? clinical features ? rx?
12 days
Fever, headache myalgia and rash (central and macular)
often get meningoencephalitis/pneumonia
they go a bit prowazzkeiii
Tetracyclines eg doxy or chloramphenicol for 1 week
Cause of scrub typhus?
Orientia tsutsugamushi
Humans infected from bites of larval mites from rodents
Scrub typhus incubation? features ? rx?
5-10 days
Eschar at the site of bite
-> headache, fever myalgia and rash
may get hepatosplenomegaly/pneumonia and delirium
Neuropsych not as pronounced as in louse bourne
Doxy
Cause of African tick typhus?
R. Africae
Found in cattle / large mammals
African tick typhus features ? rx?
-Echlar (often multiple) then central macularpapular rash
Usually self limiting but can use doxy
What is Weil’s disease
Leptospirosis with hepatic-renal failure
Leptospirosis life cycle
Small rodents and mammals - infective for live and excrete lepto in urine -> contaminates water
Enters skin though breaks or via mucosas
Key blood findings lepto ? dx? Rx mild vs severe?
Bilirubin disproportionately high
Renal function deterioration
Usually ELISA for IgM
Mild - Doxy/Azithro
Severe - IV Cef 10 days
Leptospirosis - when is an outbreak common?
Following flooding - contaminated water with rat urine
Leptospirosis microscopy requires? What are they? Other bug in this class?
Dark feild microscopy - doesnt stain
motile, aerobic spirochetes
Main pathogen lepto
Leptospira interrogans
Most common symptoms leptospirosis
Most of the infections are asymptomatic
- >90% of symptomatic illnesses
are mild
If severe:
- [Liver necrosis, tubular necrosis, meningitis, pulmonary haemorrhage
Lepto classic clinical progression? In weil’s where is best place to try and culture lepto? Which organs involved?
Biphasic symptoms
-Anicteric (non specific sx)
- Icteric (Weils)
- by now bacteria often not able to isolate - urine best
Pulm / liver / renal / myocarditis
Key indicators in death with lepto
<50k platelets: OR 6.4
creatinine >200mM: OR 5.9
lactate > 2.5mM: OR 5.1
> 1000 leptospires /mL: OR 4.3
Name 3 Key DDx of fever with myalgia, jaundice, renal failure and thrombocytopenia
Leptospirosis
Malaria
Dengue
Rickettsiosis Scrub Typhus
Typhoid
fever
Lepto Dx?
RDT
Latex agglutination
ELISA
PCR
Lepto prevention?
Immunization of cattle and pets
Reduce rodent population
Chemoprophylaxis in high-risk groups - doxy
What are the 3 most life threatening diseases for travellers? Geographic distrobution?
Falciparum = 77%
Typhoid - 11%
Lepto 3%
How does borrelia evade immune system?
Has variable small proteins, and variable large proteins
-Constantly changing
Cause of false positive and false negitive abtibody tests borriela
False positive
-Cross reaction with other spirochetes (Treponema pallidum, leptospira)
False negative
-Antigen variation (Vsp and Vlps’)
TBRF vs LBRF length of sx
relapses get shorter and progressively milder
Rickettsia - which ones causes spotted fever? Typhus? Scrub typhus?
What feature is often in Rickettsia but NOT scrub typhus
HypoNa
Rickettsia spotted fever - which species if Americas? Mediterranean / asia? Sub Saharan Africa?
R rickettsii - americas
R conorii - mediiterranean
R africae - sub saharan africa
Rash in R rickettsii
Often not present at time of presentation (fever, malaise, myalgia, headaches)
-Starts on wrists & ankles progresses to trunk
Palms & soles (36- 82%);
NO ESCHAR
May -> gangrene of digits
Rash in R. conorii
Eschar
then macular rash in 97%
Which tics in Rickettsia africae? Rash?
Amblyomma tics
Often multiple Eschars (50%)
macular rash in 50%
Rickettsia africae vs conorri vs rickettsii
Which most deadly? where found? rash?
cause of epidemic typhus? vector?
Rickettsia prowazekii
Louse - Pediculus humanus corporis
Murine typhus caused by? Usual host?
R. Typhi
Rattus rattus
[Xenopsylla cheopis - Oriental rat flea]
Papule forms at bite site -> ulcerates, forms an eschar ,
+local adenopathy
-Usually Groin, axilla, genitals
6-18 d after bite, fever, HA,myalgias .maculopapular rash and generalized lymphadenopathy
South east Asia
Cause? Vector?
Orientia tsutsugamushi - scrub typhus
- Vector: chiggers larva of mite
Key clue the eschar is scrub typhus (Orientia tsutsugamushi)?
Systemic features that help differentiate?
In the warm places
Under breast, axilla, groin, genitals
Often with hearing loss / pneumonitis or CNS involvement
What causes Q fever? incubaton
Coxiella burnetii
-Small Gram negative coccobacillus
2-6 weeks
Whos at high risk of Q fever?
abattoir workers, vets, farmers
-Cattle, sheep, goats
High concentrations in the placenta
–> bacteria released into the air during parturition
–> inhaled by humans (eg downwind epidemics)
Acute vs chronic Q fever
Acute
- pneumonia**
- Hepatitis
- Flu-like illness
Chronic
- Endocarditis
- Vasculopathy
- Osteomyelitis
Hepatits, endocarditis and pneumonia in a farmer =?
Ix?Rx?
Coxiella burnetii - Q fever
IgM or IgG
Doxy
+hydroxychloroquine in chronic disease
Spot Dx
Treponema pallidum
Why is RPR often negative in secondary syphilis?
Prozone phenomenon
Patchy alopecia which bacteria do you need to consider?
Treponema pallidum
What features would make you confident this ulcer is syphilis even if RPR/VDRL is negative?
– Painless / Non-tender to palpation
– Indurated, heaped-up border
– Clean (non-purulent) bas
- In the flashcard deck for spirochetes
30% RPR are negative in primary syphilis as pt has not yet seroconverted
What am I?
Condyloma lata
Treponema pallidum
[Fleshy, flat-topped appearance may help distinguish from warts]
2-6 weeks of generalized rash: macular, papular,
pustular, *vesicular
With some flat topped ‘warty’ lesions in crevices
[Fever, malaise, generalized
lymphadenophathy, alopecia, interstitial
keratitis, uveitis, liver/kidney involvement]
Secondary syphilis
Treponema pallidum
Secondary syphillis
Treponema pallidum
Mucous patches on background of
‘coated’ tongue
56 yo woman with HIV (CD4 716)
Eye pain, redness, photosensitivity, vision loss, retro-orbital headache, & bilateral tinnitus
* Rash over legs, palms and soles a month earlier; flat painless genital lesions
=? rx?
Ocular syphilis - often causes anterior uveitis
[or retinitis]
IVBenpen - treat ocular as neuro
Define latent syphilis - what makes it early latent?
Defined by positive treponemal serology in the absence of
clinical manifestation
<1yr - early
>1yr or unknown - late latent
‘generalised paresis of the insane’ old term for what thing that is now rarely seen?
Neurosyphilis
Dementia -> paralysis
In syphilis why is RDR/VDRL better than serology
Differentiate present infection from past
Can monitor titres and response to Rx
Strage thing about coxiella burnetii titres
Phase 2 indicate acute infection (not phase 1)
Coxiella burnetii transmission
Downwind especially of lambing
raw milk,
(tick bite / sex)
Only place with no q fever
New Zealand
Key risk factor for complications with Q fever
Endovascular eg prosthetic valves, aneurysms
[immunosupression]
Q fever in pregnancy Rx?
If valvuloplasty?
Co-trimoxazole throughout preg
Doxy + hydroxychloroquine 12 months
Chronic - Doxy + hydroxychloriquine
[if prosthetic valve + surgical]
diagnostic Q fever
Phase 2 ELISA IgM/IgG
PCR
How much Coxiella burnetii to be infectious? How many get chronic infection?
<10 bacteria
5% get chronic infection
[40% if prosthetic valves]
20m arrived in Tripoli (Libya) from Malawi; human traffickers put him in overcrowded accommodation
shared with Somalis
+1 week developed fever lasting 5 days, resolved then another fever now
Blood film
rx?
Borrelia recurrentis
Louse-borne relapsing fever (LBRF)
Doxy single dose (or ceftriaxone)
-60% get jarisch-herxheimer reaction
Louse born relapsing fever transmission
contamination of broken skin/intact mucosae
by coelomic fluid of lice inoculated by scratching (NOT
feeding)
Prevent louse-born relapsing fever
Lives in clothing -> washing and hygiene
Name 3 louse born infections
Rickettsia prowazekii ,
Borrelia recurrentis
Bartonella quintana
[Yersinia pestis
Acinetobacter baumannii]
Why do you get the relapsing fever in relapsing fevers
Successive appearances of Borrelia spirochaetes expressing different Variable major outer Membrane lipoProteins
Name 3 complications of LBRF
-Uterine bleeding, abortion
- Myocarditis -> acute LVF and pulmonary oedema
-Hepatic failure
- Severe bleeding (thrombocytopenia, DIC)
- Splenic infarction and rupture
- Secondary bacterial infection: (Salmonella, typhoid, Shigella , malaria, typhus, tuberculosis)
[Due to temporary immunosuppression]
TBRF reservoir
Humans
ticks are vectors and reservoirs too
Difference in Rx/Distribution/neurological effects of with LBRF and TBRF
1 dose for LBRF
10 days in TBRF
LBRF - horn of africa + south sudan
TBRF - over world
Which rickettsia causes gangrene of extremities
Rickettsia prowazekii
Child with this lesion
Yaws (framboesia)
(“framboise” French for “rasberry”)
Will have loads of spirochetes
previous ulcer then this rash?
Other things they get?
Secondary yaws
osteoperiostitis
Hyperkeratotic plantar yaws
“crab” Secondarily infected painful, lesions and
cracks enforcing crab like walk on outsides edges of feet
- Destructive osteitis of palate and nasopharynx
- Hypertrophic periostitis causing bowing of shins
(sabre shin) and exostoses of the paranasal maxilla (goundou)
Seen in?
Tertiary yaws
