Borreliae and Leptospira are two important pathogenic spirochetes. Borreliae cause Lyme disease and relapsing fever. Leptospira interrogans causes leptospirosis, also known as Weil's disease, and is transmitted through contact with contaminated water or soil. It can cause a range of symptoms from mild fever to severe jaundice or meningitis. Diagnosis involves microscopy, culture, serology including MAT, and PCR. Treatment is with doxycycline or penicillin depending on severity. Prevention involves chemoprophylaxis, rodent control, and disinfection.

1. SPIROCHETES II
BY MARY MWINGA

2. BORRELIA
Borreliae are large, motile, refractile spirochetes.
Have 3-10 irregular and wide open coils.
Size: 5-30 µm long and 0.2-0.6 µm wide.
They stain readily with dyes and are Gram negative.
It is a normal mouth commensal.
Pathogenic under conditions such as malnutrition or viral infections.

3. Important pathogenic borreliae of medical importance includes:
-B. recurrentis: cause relapsing fever.
-B. vicentii: causes Vincent’s angina in association with fusiform bacilli.
-B. burgdorferi- causes Lyme disease.

4. LEPTOSPIRA
Belongs to the genus Leptospira.
They are actively motile with endoflagellum, delicate spirochetes.
Possess numerous closely wound spirals with hooked ends.
They do not stain readily.
They may be observed by dark ground illumination.

5. History:
first described by Weil (1886) –caused leptospiral jaundice in humans.
Stimson (1907) observed slender spirochetes in silver-stained sections
of kidneys from a fatal case of jaundice.
Saprophytic leptospires were isolated from water, sewage and other
sources.
Classification: Leptospira species
a)L interrogans:-causes leptospirosis or Weil’s disease.
-Pathogenic for humans.
b) L. biflexa –saprophyte (non-pathogenic).

6. LEPTOSPIRA INTERROGANS
Morphology
They are spiral bacteria.
Size: 5-20µm long x 0.1µm thick.
They have numerous closely set coils wand hooked ends.
Actively motile, posses a single endoflagellum attached to the pole.
Stain poorly with aniline dyes but observable by fluorescent antibody
and silver impregnation techniques.
Best observed by dark ground, phase contrast or electron microscopy
due to narrow diameters.
They rotate readily about their long axis and bending or flexing sharply.

7. Figure 1: Leptospira- dark ground
illumination

8. CULTURE CHARACTERISTICS
They are aerobic and microaerophilic.
They grow in media enriched with rabbit serum.
Liquid and semi-solid media such as Korthof’s, Stuarts's and
Fletcher’s media are used.
Semisynthetic media: such as Ellinghausen, McCullough, Johnson,
Harris (EMJH) media.
In semi-solid media: grow a few millimetres below the surface.
Incubation at 25-30°C and pH 7.2-7.5.
Generation time in media is 12-16 hours, in inoculated animals 4-8
hours.

9. Leptospires can also be grown on chorioallantoic membrane (CAM) of
chick embryos.
Resistance:
heat labile: killed at 50°C in 10 minutes and at 60°C in 10 seconds.
Sensitive to acid, they are destroyed by gastric juice and bile.
Readily destroyed by chlorine and other antiseptics and disinfectants.
survive for days in moist conditions at pH 6.8-8.

10. PATHOGENICITY
Leptospiral infections are asymptomatic.
Diseases results when infection is transmitted from one animal to another.
Leptospires have endotoxin-like component- cause fever, inflammation and
necrosis of tissues.
Haemolysin- lysis RBCs results in anaemia.
cytotoxicity factor- cause muscle spasm and dyspnoea.

11. Diseases
Leptospirosis:
is a zoonotic disease in rodents caused by L. interrogans.
Transmission in Humans:
Indirect contact: though water, soil or moist surface
contaminated by urine of carrier animals
Direct contact:-Through cuts or abrasions on skin or
 -Through intact mucosa of the mouth, nose or
conjunctiva.

12. Incubation period: 10 days (range from 2 – 26 days).
Risk factors: -lower socioeconomic status
-rainfall and floods
-occupational exposure to urine. e.g. rice fields, farmers.
Epidemiology
It is distributed worldwide.
High in areas highly populated such as Brazil, India and Thailand.

13. Weil’s disease:
involves hepatorenal damage associated with mild and undifferentiated
pyrexia.
in severe cases: onset is acute, with rigor, vomiting, headache and
intense injection of the eyes.
fever is irregular and subsides within 10days.
Other diseases:
Aseptic meningitis.
Renal failure.
Jaundice.

14. LABORATORY DIAGNOSIS
Specimens: CFS, blood and urine.
1. MICROSCOPY:
Wet films: observed in blood and urine under phase contrast or dark ground
microscope.
staining: they are stained by silver impregnation stains such as Fontana stain and
modified Steiner technique.
Appearance: L. interrogans is 6-12µm long and 0.1µm wide.
-tightly and regularly coiled with characteristic hooked ends(resemble an umbrella
handle).
-highly motile; exhibit spinning ad translational movements.

15. Disadvantage of Microscopy:
Less sensitive
Requires technical expertise
Serum proteins and fibrin strands in blood may resemble similar to
Leptospires.

16. 2. CULTURE
Conditions: Leptospira is an obligate aerobe, slow growing
Cultures inoculated at 30°C for 4-6 weeks at pH 7.2 – 7.5.
Media: it is highly fastidious and requires enriched media.
On EMJH medium: it is composed of albumin fatty acid supplement
added to the basal media containing 0.1% agar.
-Growth: dense ring of organism under the surface of the medium
(Dinger’s ring).
Korthof’s and Fletcher’ semi-solid media can also be used.

17. 3. ANIMAL INOCULATION
Blood or urine from patients is inoculated intraperitoneally into young
guinea pigs.
Peritoneal fluid is examined for Leptospires by dark ground
illumination.
4. SEROLOGICAL TESTS
a) Antibody detection
IgM antibodies: appear early within one week of illness.
IgG antibodies: appear later than IgM after few weeks.

18. Antibody tests
Screening tests- they are genus specific.
 includes complement fixation test, hemagglutination test, enzyme-
linked immunosorbent assay (ELISA), sensitised erythrocyte lysis
(SEL), agglutination test and indirect immunofluorescence.
Serotype Specific tests
Microscopic and macroscopic agglutination test (MAT) detects
antibodies against serovars of L. interrogans.
it is a gold standard method for diagnosis of leptospirosis.

19. b) Cross agglutination and absorption test (CAAT)
Detects the relatedness between the strains.
5. MOLECULAR METHODS
Polymerase chain reaction (PCR).
TREATMENT
Mild leptospirosis: oral doxycycline (100mg twice a day for 7days) or amoxicillin.
Severe leptospirosis: penicillin (1.5 million units a day for 7 days) or tetracycline,
erythromycin, ceftriaxone or cefotaxime.

20. PROPHYLAXIS
Chemoprophylaxis with doxycycline.
Rodent control.
Disinfection of water.
Wearing protective clothing.
Health education.