Brucellosis
Case Report
a 45M goat herder in Malaysia develops 3 weeks of fevers, lethargy, night sweats and headache
history revealed he drank unpasteurised milk from said goats, which he also sold to consumers
blood cultures were negative and he tested negative for more common tropical diseases such as malaria, dengue, typhus and lepto
eventually he tested positive for brucella serology, unfortunately about 80 people also developed brucellosis from drinking milk from his farm, and a few lab staff also picked it up from handling their blood samples
consider this differential in PUO
Microbiology
causative organism: Brucella melitensis
gram negative coccobacillus, facultative intracellular
hardy bacteria that can survive prolonged periods in meat/dairy products unless pasteurised/cooked as well as dust & surfaces
picked up in the intestinal submucosa on ingestion and transported by macropahges to lymphoid tissue
it then has the possibility of spreading haematogenously in the liver, spleen, joints etc. causing systemic or localized infection
Transmission
zoonoses (animal associated)
in particular: feral pigs, so hunters are often at increased risk (due to handling the carcasses), but also cattle, sheep, goat and dogs
outbreaks often associated with consumption of unpasteurized milk from infected animals
Epidemiology
global and notifiable disease in most countries
endemic to Mediterraena, South America and the indian subcontinent
in Australia - largely QLD and NT, but now NSW
Increased risk groups (i.e. what to ask on history and what clues on history to consider for brucellosis)
regular contact with animals (herders, abbatoir workers, vets - there are case reports of lab workers who pick up brucellosis etc)
people who ingest unpasteurized dairy/milk, or the undercooked meat of infected animals
History
first described by another European white man, Dr. George Cleghorn, British Army Surgeon in minorca in 1751 on the island of Malta following the Crimean war
it was named for another British white man, Sir David Bruce who led a commission into a fever outbreak among the army in Malta before they found the organism causing the disease (Sir Themistocles Zammit identified that goats transmit it in milk)
Sir bruce also discovered that trypanosoma brucei (also named for him) was the microbe responsible for animal trypanosomiasis/sleeping sickness. incidentally, he was born in Melbourne Australia
trivia with the Crimean war - was ironically a war fought between Russia and the UK + it's Western Allies and the empire that preceded Turkey (Ottoman)
Today the Crimean war is more well known for producing Florence Nightingale, founder of modern nursing and yay, finally a woman in random medical history that hardly is related to brucellosis.
Clinical features
PUO - cyclical fevers, fatigue, headache, insomnia, myalgias/arthralgias, weight loss, anorexia (fairly non specific, but also systemic)
incubation times can be long, which can be deceptive, reportedly up to 50 yrs from first exposure
otherwise, most cases it ranges from 3 days to several week, on average, expect 2-4
sometimes: hepatosplenomegaly
critical on history to clarify travel/living situation or contacts and consumption of unpasteurised dairy or undercooked meat
localized disease also possible, depending on organs involved
up to 40% will report peripheral arthritis, sacroillitis and spondylititis (kinda sounds like ank spa), at worst can cause osteomyelitis and septic arthritis
endocraditis is a rare but serious complication, with a 5% mortality rate, outside of this it's rarely fatal
if the lungs are affected, cough and SOB can occur but hte CXR will be lcear
GBS has been reported to occur following infection
hepatic abscess and granulmoa in a few
also possible: epididymoorchitis and skin manifestations like erythema nodosum
ocular changes like uveitis, cataracts etc.
it really feels rheum flavoured.
Investigations
hints on basic bloods - neutropaenia and anaemia, thromobcytopaenia in the case of hepatosplenomegaly or ITP
raised ESR and CRP, ALP and LDH
elevated LFTs in hepatomegaly
but diagnosis: blood cultures --> can take weeks as slow growing (due to aerosol transmission, must be handled in a biohazard hood as with the case report)
key really: serology is the most commonly used tool
PCR can also be used, including 16S
tissue also an option depending on organ affected
Management:
atypical cover: azith and doxy
several weeks of treatment usually - i.e. if uncomplicated, doxy for 6 weeks (however relapses are common on monotherapy, up to 40%), often rifampicin 600 mg daily for 6/52 is also added or gentamicin
where doxy can't be used, bactrim is the alternative
Sources
CDC guideilnes
WHO guidelines
ETG - behind a paywall, if your institution covers it, uptodate is gold standard, that said, plenty of free resources that provide a great start
Wikipaedia
Statpearls
Case report (There's actually a lot of background pathophysio, investigations and treatment listed in case reports and many are free)
