Leptospirosis

Question 1

Leptospirosis - organism

Answer 1

Leptospira spp - spirochaete
Free-living, aerobic
Motile

21 species = 9 pathogenic, 5 intermediate, 7 non-pathogenic

Question 2

Leptospirosis - transmission

Answer 2

Zoonosis - direct or indirect contact with animal [usually rodent] urine

Survive for weeks in fresh water
Invade intact skin or mucous membranes

Question 3

Leptospirosis - burden

Answer 3

1 million cases
58,000 deaths annually

3rd commonest infectious cause of life-threatening disease in returning travellers

Question 4

Leptospirosis - epidemiology

Answer 4

Tropical and temperate regions
Men>Women
Mortality 5-14% in confirmed cases - up to 40% if untreated

Question 5

Leptospirosis - clinical manifestations

Answer 5

IP 3-30 days [generally 7-12 days]

Weil’s disease

Uncomplicated non-specific febrile illness with spontaneous resolution

May have biphasic pattern:
-Early septic phase = non-specific febrile illness lasting 3-9 days, fever, chills, myalgia, headache
-Immunological phase - complications can occur, IgM detectable in blood and leptospira in urine

Question 6

Weil’s disease - clinical manifestations

Answer 6

Febrile illness with:
-Jaundice
-AKI
-Conjunctival suffusion [develops in 1st week of illness]

Question 7

Leptospirosis - complications

Answer 7

10%
Rhabdomyolysis
Jaundice
AKI with hypokalaemia
Prulmonary haemorrhage
Myocarditis
Aseptic meningitis
Multiorgan failure
Rare = encephalitis, peripheral nervous system [neuritis, radiculitis, optic neuritis]

Question 8

Leptospirosis - pathophysiology

Answer 8

Organ damage from direct pathogen insult as well as hosts immune response
-Deranged tissue microcirculation and endothelial dysfunction
-Direct hepatocellular damage and acute tubular damage

Question 9

Leptospirosis - lab findings

Answer 9

Non-specific lab findings:
-Leucocytosis, thrombocytopenia
-Elevated CRP
-AKI
Elevated conjugated bilirubin
-Anaemia
-Clotting normal - no DIC
-Urinalysis - protein, blood, pyuria

Question 10

CNS leptospirosis - lab

Answer 10

Lymphocytic pleocytosis
Elevated protein
Normal glucose
Can mimic viral meningo-encephalitis

Question 11

Leptospirosis - diagnosis

Answer 11

Compatible clinical syndrome
PLUS
Exposure history
PLUS
Detection of leptospira DNA or serological response [IgM]
-Restrospective = MAT, culture

PCR:
Blood - positive in 1st week of illness
Urine - positive 1st week and after

IgM-ELISA:
IgM positive day 6-10 of illness
Cross-reactivity - EBV, hep A, scrub

Reference tests:
-Dark field microscopy
-Culture - sample in 1st week of illness, temp 28-30 degrees with specific media, low diagnostic yield
-MAT - serological gold standard, single titre >1:400 or 4-fold rise between acute and convalescent sera

Question 12

Leptospirosis - managment

Answer 12

Majority mild and spontaneously resolve

Antibiotics:
-IV benzylpenicillin or ceftriazone
-Doxycycline PO [azithromycin or amoxicillin]
-Standard course 5-7 days

Caution with Jarisch-Herxheimer reaction

Supportive management

Question 13

Leptospirosis - prevention

Answer 13

Sanitation
Modifying risks
Antibiotic prophylaxis - doxycycline weekly
Vaccination = routine of animals, but human vaccine not available at present