Meloidosis, JEC, Ricketsia, Scrub Typhus and Q fever Flashcards
What kind of bacteria causes melioidosis?
Intracellular GNR
Burkholderia Pseudomallei
What are the clinical manifestations of mel?
CAP, sepsis, skin lesions
Where is Meloidosis tx from?
Water and soil
Aquisition can be percutaneous, some GI acquisition
Associated with rains and wet seasons
Where is meillodis endemic?
Highly endemic in SE asia
Increasingly recognised in India, West Africa, Americas
Aromatherapy from India brought it into USA
What are risk factors for meilloidosis?
DM
Alcohol
Chronic renal disease
Chronic lung disease
Clinical manifestation of melloidosis?
Pneumonia most common
Skin ulcers and abscesses 2nd most common
Visceral abscess and osteomyelitis
Bacteraemia in 55% with 20% mortality
What are some CXR findings in melioidosis?
Bilateral
Pneumothorax
Can be anything
Most common site of abscess of melioidosis?
Prostate
How does chronic melioidosis present?
More than 2 months of sx
Resembles TB: fever, weight loss, cough, upper lobe infiltrates and cavitation
How do you Dx Meiloidosis?
Gram stain and culture
Antigen detection assays allow rapid diagnosis with good specificity
Tx of Mel?
IV ceftazidime or Meropenem
Floowed by co-trimoxazole
50y/o farmer from Thailand presented with cough and fever for 10 days, prior history of DM. Labs showed raised WCC
Melioidosis
Traveller returned from vacation in Bali with fever, headache and confusion. Developed falccid paralysis, altered mentation and resp failure?
JEC
What does encephalitis present like?
Fever, headache, N+V with altered mental status and personality
Where is JEC endemic?
Endemic tropical regions of Malaysia, Indonesia and Philippines
Who get more JEV kids or adults?
Kids, but adults more complicated and increased mortality
What are the vectors of JEC?
Culex tritaeniorhynchus
Who are the maintenance and amplifier hosts in JEC?
Maintenance is heron birds who have viremic reservoir
Pigs are amplifiers
Humans are dead end host
How does JEC present?
90% asymptomatic
10% febrile
Neuroinvasive in 0.4%
What are the clinical features of JEC?
6 to 16 day incubation period
Fever, vomiting, confusion, seizures, photophobia
What are the Neuroinvasive features of JEC?
Aseptic meningitis, encephalitis, acute flaccid paralysis and ascending paralysis
CT findings show basilar ganglion associated with EPS
What does LP of JE show?
LP shows normal to increased protein, pleocytosis, mainly lymph and normal glucose
Dx of JEC?
PCR only positive initially
Ideally want CSF IgM
Vaccine for JEC and who gets it?
2 doses, 28 days apart
Inactivated vaccine
If exposed for >1 month in rural area during rainy season
What do you do to prevent JEC in endemic areas?
Universal childhood vaccine
What is seasonality of JEC?
May-October which encompasses monsoon season
Year round in equatorial areas like Indonseia, Malaysia, Philippines and South India
What type of organism is ricketsia?
Gram negative rod
Which vectors transmit ricketsia?
Predominantly ticks, but also lice/fleas/mites
How does ricketsia present and what are the labs?
Fever, malaise, myalgias
Labs: Raised transaminases, WCC can be low or normal
What are the main spotted fever of rickettsia?
Rickettsia Ricketsii This is found through the Americas, is the most severe
Rickettsia Conorii is found in Mediterranean, Africa and Asia medium severity
Rickettsia Africae is African tick bite fever, least sever and found in Subsaharan Africa
What does R. Rickettsia present like?
Sudden onset high fever and Rash
Endemic in US, mExico, Central and South America
Causes damage to microcirculation– hypovolaemia, gangrenous skin or digits
High case fatality if untreated
What is Rash of R Rickettsii like?
Starts on wrists and ankles, commonly is found on palms and soles
No inoculation eschar
Rash can take while to develop
What is Mediterranean Spotted fever?
Rickettsia Conorii
How does Rickettsia Conorii differ in presentation?
Febrile illness with eschar at site of tick bite
Macular rash
How does Rickettsia Africae present?
Does not cause much damage to the ticks
Typically multiple infected tick bites at the same time–multiple ecschars
Rash, typically self resolving
Differences in rickettsiae, what do they all present with?
All present with sudden onset fever and myalgias
R Africae is less pathogenic and has multiple eschars
R Conorii which more pathogenic and a singular eschar
R Rickettsii is the most pathogenic and has no eschar (in Americas)
What is official name of epidemic typhus?
Rickettsia Prowazekii
How is Rickettsia Prowazekii spread?
Pedicilus humans corporis
Lives in clothing
Associated with outbreaks due to war, famine, cold
What is Murine or Endemic Typhus?
Rickettsia Typhus spread by rat and possum fleas
How does Murine Typhus present?
No eschars
Fever, myalgia
Rash presents late and is typically on trunk and spreads outwards
How do you Dx ricekettsia?
Serology, but this is not species specific. Get a lot of cross-species reaction. Typically not positive at time of presentation
Typically treat empirically with doxy and response is quick
Tx of Rickettsii
Doxycycline
If no doxy use chloramphenicol +/- Cipro or Levofloxacin
44y/o farmer from South India presents with 7 days of fever, headache vomiting and SOB. Dx?Small black scab in left groin, no Rash or lymphadenopathy. Mild hepatomegaly.
Scrub Typhus
Orientia Tsutsugamushi
How is O. Tsutsugamushi spread?
Mites called chiggers, the young 6-legged mite
Humans are accidental hosts
Rats are the reservoir
How does scrub Typhus present?
Papule at bite site
Ulcerates, forms eschar
Myalgias, rash and generalised lymphadenopathy 1/52 later
Where is Tsutsugamushi found?
Asia and a small part of Australia
When is Scrub Typhus typically spread?
Warmer months and temperate regions
Dry season in India
Mainly rural
Where is eschar of scrub Typhus typically found?
Axilla, chest, abdomen, groin and genetalia
What is clue to differentiate Lepto from scrub typhus?
Lepto in wet season, Scrub Typhus in dry season
What organs are typically involved in scrub typhhus?
Elevated liver enzymes
Thrombocytopenia
Pneumonitis
CNS involvement
How do you Dx Scrub Typhus?
PCR which is highly sensitive and specific
Antigen detection tests
How do you treat and prevent scrub typhus?
Doxycycline
Weekly doxycycline can be used as pre-emptive therapy
Presentation of scrub typhus?
Common in South and SE Asia
Undifferentiated febrile illness
Eschar, hearing loss, pneumonitis, sepsis and CNS involvement
What is Q fever organsim?
Coxiella Burnetti
What kind of organism is coxiella Burnetti?
Small gram negative coccobacillus
Who is particularly at risk of Q Fever?
Abattoir workers, vets, farmers
In placenta of animals main reservoir is sheep, goats and cattle
How does Q fever present clinically?
Looks like an atypical CAP
Fever/fatigue/chills/cough
Hepatitis
Chronic Q fever involves endocarditis, vasculopathy and osteomyelitis
What is typical of chronic Q fever?
Culture negative Endocarditis
Organ involvement of acute vs chronic Q fever?
Acute is hepatitis and Pneumonia
Chronic is endocarditis and vascular infection
How do you tx Q fever?
Acute is doxycycline
Chronic is doxycycline and hydroxychloroquine
How do you Dx Q fever in acute v chronic?
Acute is IgM or IgG
Chronic is IgG
