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Module: BIOM - 1009

Lecturer: Dr Peña-Fernández

Date: 31/10/16

Spirochetes
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Spirochetes are a group of morphologically unique, Gram-negative bacteria
 They are motile and tightly coiled
 They are usually found in water environments (in sediment) and in animals
 Some spirochetes cause diseases such as syphilis, a sexually transmitted disease
 They contain endoflagella
 These are special flagellum found only on spirochetes that, instead of protruding the
environment, spiral tightly creating a corkscrew effect
 This is done due to the use of axial filaments that wrap around the bacterium
 This movement allows pathogenic spirochetes to burrow through the hosts tissue
 The following are some specific medically important spirochetes

Treponema pallidum
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T
...
2 µm in diameter
It cannot be visualised under a bright-field microscope and instead should be observed under a
dark-field microscope
T
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pallidum is pathogenic to humans only and affects humanity worldwide
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It is sensitive to environmental conditions however and so is an obligate parasite of humans
It has two modes of transmission:
 Sexual contact
 Mother to foetus
Syphilis kills 100,000 people per year whereas gonorrhoea, another STI only kills ~1000 people
per year
It is particularly prevalent among sex workers, homosexual men and users of illegal drugs

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The disease that T
...
causing skin rashes
 Latent
 This is the clinically inactive phase that most cases of syphilis do not pass
 It is defined as having serological proof of the disease without having the symptoms
 Tertiary
 This may occur 3-15 years after the initial infection and can be split into 3 types:
 Gummatous
 Neurosyphilis
 Cardiovascular syphilis

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Congenital syphilis, caused by mother to foetus transfer can result in:
 Foetal death

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Mental retardation and malformation

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Treatment of T
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pallidum

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There are other Treonemal diseases caused by subspecies of Treponema pallidum:
 T
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pallidum pertenue – Yaws
 T
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pallidum:

Borrelia
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Borrelia is a genus of bacteria from the family spirochaetaceae
 There are 52 known species of Borrelia
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They are lightly staining spirochetes and are the causers of 2 diseases:
 Lyme disease
 Relapsing fever

Lyme disease, caused by the bacteria B
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 Mild winters
Lyme disease can be treated with:
 Penicillin
 Doxycycline
 Treatment at later stages will be difficult
The disease can be prevented by avoiding ticks

Relapsing fever is caused by the bacteria
 It is transferred to humans via louses or ticks
 Tick-borne
 Caused by B
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interrogants is a species of motile, obligate bacteria


It causes zoonotic disease because it is found in both wild and domestic animals

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Transmission can be through the following:
 Direct contact with urine infected animals
 Indirect contact with animals through infected lakes, streams etc

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The bacteria eneter trhough cuts in the skin or mucous membranes and can burrow into the hosts body
 L
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The symptoms of this infection include:
 Haemorrhaging
 Liver failure
 Kidney Failure

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It can occur worldwide and does not usually produce fatal results
 It is estimated that between 7-10 million people are infected annually

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Leptospira can be treated with intravenous antibiotics such as:
 Penicillin
 Amoxicillin
 Doxycycline

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You can prevent Leptospira infection by:
 Using rodent control to limit spread
 Use the vaccine for livestock and pets
 Wear approprate clothing
 Dressing wounds

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The following are images of Leptospira:



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