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Rickettsial infections, brucellosis and Meliodiasis
Rickettsial infections, brucellosis and Meliodiasis
72
Medical
Professional
05/29/2021

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Term
name 3 main types of typhus seen worldwide
Definition
Louse borne typhus
Scrub typhus
African tick typhus
Term
Louse bourne typhus is caused by which Rickettsia?
Definition
Rickettsia prowazekii
Term
Louse borne typhus caused by R prowazekki and transmitted to humans by?
Definition
infected faeces of human body louse pediculus humanus. It is usually scratched into the skin
Term
in which type of populations does louse borne typhus occur in?
Definition
malnourished migrants with poor hygiene e.g refugee camps
Term
clinical features of louse borne typhus
Definition
incubation 12 hours
fever/myalgia/headache then prostration
Conjuctival suffusion
Term
Describe the rash of louse borne typhus which appears on day 3-4?
Definition
central and macular
there is also conjunctival suffusion
Term
how is louse borne typhus diagnosed?
Definition
clinical dx in epidemics
PCR
Weil-Felix serological test can be used (pCR better)
Term
treatment fro louse borne typus?
Definition
Tetracycline or chloramphenicol 7/7
Supportive care
Term
Preventitive measures in epidemic of louse born typhus?
Definition
Delousing procedures
200mg doxycycline single dose to all those at risk
Term
rickettsial prowazekki causes....
Definition
louse borne typhus
Term
scrub typhus AKA
mite tyhus AKA.....
Definition
Tsutsugamushi fever

caused by orienta tsutsugamushi/rickettsia tsutsugamushi
Term
scrub typhus caused by?
Definition
Orienta tsutsumagushi aka
R tsutsumagushi
Term
Scrub typhus is a zoonosis of?
Definition
rodents

Humans are infected by bites of infected larval mites
Term
HOw are humans infected in scrub typus?
Definition
by bites from infected larval mites.

It is naturally a zoonosis of rodents
Term
clinical features of scrub typhus?
Definition
5-10 day inc period
Eschar at site of mite bite
fever/headache/myalgia/prostration
Similar rash to louse borne typhus
Term
scrub typhus and weil-felix test??
Definition
Weil-Felix is insensitive in this form of typhus.
Dx is clinical
Term
louse borne typhus caused by?
scrub typhus caused by?
Definition
Louse borne - R prowazekki
Scrub typhus - R tsutsugamushi
Term
treatment for scrub typhus?
Definition
tetracycline and chloramphenicol

Simplest and optimal rx is doxycycline 200mg 3-7 days
Term
prevention of scrub typhus?
Definition
avoid mite infested areas
impregnation of clothing with permethrin
prophylactic doxycycline in high risk areas
Term
where does scrub typhus occur?
Definition
SE asia
Oceania
North austrailia
Term
causative organism for African tick typhus?
Definition
R africae
Term
Organism causing rocky mountain spotted fever?
Definition
R rickettsii
Term
incubation period for rickettsial illnesses?
Definition
5-14 days
Term
where do rickettsias localise once they are inoculated into the human body?
Definition
endothelial lining of small blood vessels causing vasculitis
Term
are all rickettsial disease vector borne?
Definition
No they are not all vector borne
Term
what sing might indicate a rickettsial infection at mite bite site?
Definition
eSCHAR
Term
Which drugs are recommended to rx rickettsial diseases?
Definition
tetracycline
chloramphenicol and doxycycline
Term
Borrelia recurrentis is transmitted by?
Definition
Pediculus Humans corporis
Term
what does the soft tick Ornithodoros transmit?
Definition
Various types of borrelia relapsing fevers
Term
Xenopsylla cheopis transmits?
Definition
plague
Term
Which bacteria causes plague?
Definition
Yersinia pestis
Term
Jigger flea transmits?
Definition
Tungiasis/tunga penetrans
Term
Hard ticks aka
Definition
Ixodidae
Term
soft ticks aka
Definition
Ornithodoros
Term
plague flea aka
Definition
Xenopsylla cheopis
Term
vector of louse borne eoidemic typus due to R prowazekki?
Definition
Human body louse
pediculus humanus corporis
Term
vector for scrub typus?
Definition
Chiggers (larval mites ) - Trombiculidae
Term
name the 4 different types of vectors for rickettsial infections
Definition
Louse typus
Mite typus
Tick typhus
Flea typhus - R typhi
Term
What causes flea borne typhus?
Definition
R typhi
Term
epidemic typhus does not present with which sign?
Definition
Eschar
Term
ricketsiall bacteria are?
Definition
short gram - rods
Term
All rickettsial illnesses respond to which medication?
Definition
Doxycycline
Term
where is brucellosis more common in?
Definition
Agrarian societies
Term
how long is duration of rx for brucellosis?
Definition
min 6/52 with at least 2 abx
Term
most reliable method of dx brucellosis?
Definition
BC

the most common method is serological testing
Term
What needs to be done to diagnostic cutoffs when serology testing in endemic areas?
Definition
They need to be set higher in endemic areas compared to non endemic areas
Term
4 types of brucellosis known to cause human disease
Definition
B abortus
B canis
B mellitensis
B suis
Term
Most prevalent and most virulent Brucella species?
Definition
B mellitensis
Term
How is brucellosis transmitted from animal to human?
Definition
ingestion of infected food products
direct contact with infected animal
inhalation of aerosols
Term
which gram - coccobacillus is a common cause of abortions in animals?
Definition
Brucellosis
Term
in brucellosis endemic areas, a person with difficulty walking is...
Definition
Brucellosis until proven otherwise
Term
DDX of spine tb?
Definition
brucellosis
Term
rx for brucellosis?
Definition
Doxycycline and rifampicin for 6-12 weeks
Term
preventing brucellosis
Definition
vaccinate animals
in low endemicity regions - test and cull affected animals
Pasteurise milk and cook meat properly
Animal hygine handling
Public education
Educate healthcare staff about diagnosis
Term
Brucellosis aka
Definition
Mediterranean/Malta fever
Term
we dont have brucellosis in the uk!!

you need to have a...
Definition
Travel hx and/or someone who has been eating lots of soft/unpasteurised cheeses
Term
what is special about brucellosis BC?
Definition
Prolonged culture
Also cat 3 pathogen (speak to lab as biohazard and requires specific conditions)
Term
in animals brucellosis important causes of.... (3)
Definition
abortion
infertility
epididymitus
Term
how long brucellosis BC be incubated for?
Definition
6/52
Term
why is the incubation period several weeks to months for brucellosis?
Definition
the organism can remain hidden in the reticuloendothelial system
Term
which organism causes Melioidiasis?
Definition
Burkholderia psuedomallei

gram - bacillus
Term
which is most effected country for melioidiasis?
Definition
Thailand
Term
pathogenesis of melioidosis?
Definition
acquired by inoculation of contaminated soil or water but may occur by inhalation too.
Term
signs and symptoms of melioidosis
Definition
most asymptomatic
localised abscess
organisms can remain latent within macrophages and cause disease many years after infection.
Term
what do 70% of pts with melioidosis have?
Definition
pre disposing disease t2dm, ckd, cirrhosis, cancer, etoh xs inc binging and steroid therapy.

There is no association with HIV
Term
clinical features of melioidosis?
Definition
Pneumonia
Fever
Skin abscess
Abscess on liver and spleen
Septicaemia (a/w poor prognsois)
Term
dx melioidosis?
Definition
definitive dx by culture of organism from blood/pus
Term
rx melioidosis
Definition
Parenteral ceftaziime or a carbopenam for min 10/7

PO maintenace therapy required after ivabx for 20/5 (Doxy and Septrin)
Term
why is melioidosis difficult to rx?
Definition
B pseudomonas is intrinsically resistant to a large number of abx
Term
what is the acute mortality from melioidosis?
Definition
20-50% worldwide
Term
melioidosis is a zoonotic disease? T/F
Definition
true
Term
name the gram - bacilli typically found in rice/paddy fields in se asia esp Thailand
Definition
melioidosis
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