5. Spirochaetosis

Describe spirochaetes

Spirochetes are gram-negative, motile, spiral bacteria characterized by the presence of endocellular flagella enclosed by an envelope. Most spirochaetes are free-living and anaerobic, but there are numerous exceptions. Many organisms are important in vet and human medicine and can cause prevalent diseases in a wide range of hosts

How are spirochaetes cultivated?

Cultivation is difficult, some grow only in liquid media, most require specialized methods. 

What are the pathogenic members of spirochaetes and which diseases do they cause?

* Leptospira - Leptospirosis
* Borrelia - Lyme disease
* Treponema - Syphilis
* Serpulina – Brachyspira

What is the aetiology of Lyme disease?

**Lyme disease** is a common **zoonotic tick-borne** disease caused by the bacteria Borrelia; a gram -ve bacteria. It is responsible for the development of **erythema chronicum migrans** in humans, which is one of the first signs and can disappear and recur.

*Complex* ***B. burgdorferi sensu lato****: B. burgdorferi sensu stricto, B. afzelii* and *B. garinii*.

What is the epizootiology of Lyme disease?

Worldwide. Lyme disease has a **natural focal** character and is seasonal in temperate areas. Typical in springtime (nymphs feeding) and summer/autumn (adults feeding).

**Incubation time is very variable. From days to years**. Professional risk!

What are the hosts of Lyme disease?

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Many but mainly affect – **dog**, horse, cow, small Ru, also humans and birds

**Reservoirs – small rodent, birds, insectivores**

How is Lyme disease transmitted?

Transmitted by the **tick vectors** of the family Ixodae. *Ixodes ricinius.* A seasonal disease with **cyclic interstadial transmission over a 3 year cycle**

What is the pathogenesis of Lyme disease?

The bacteria migrate from the feeding tick midgut to the salivary glands. When the tick feed, the bacteria is deposited in skin, while evading the localized host immune response. It then adheres to and migrate through an endothelial barrier, replicates and is spread via blood or lymph to establish infection in distal tissue sites. 

Immunocomplexes cause alteration of kidneys and joints

*Borrelia burgdorferi* proteins mediate many of these processes

What is the incubation period of Lyme disease?

weeks to months. Very variable clinical presentation but joint inflammatory syndrome is common

What are the clinical signs of Lyme disease?

Very variable clinical presentation but **joint inflammatory syndrome** is common

**erythema chronicum migrans** 🡪 typical symmetrical round shape

Forms: **acute, chronic, asymptomatic**. 

Postinfectional antibodies – IgG peak in 4–6-week p.i. And remain for at least 1 yr. 

Fever, inappetence, lethargy, lymphadenomegalia, lameness, swollen joints, glomerulonephritis, uveitis, abortions, encephalitis, erythema, CV

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In humans – 3 stages:

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* **Influenza like signs**
* **Erythema chronicum migrans**
* **Skin, joints, CNS**

What is the diagnosis for Lyme disease?

Serology, isolation (Barbour-Stoner-Kelly, blood, urine, CSF, haemolymph), and detection of Ab (**ELISA**, IFA), detection in native preparations in dark field microscopy, Ag impregnation, PCR

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Snap test (C6- ab immediately synthesized)

What is the treatment for Lyme disease?

Antibiotic therapy for at least 2 weeks, usually months. Penicillin and tetracycline groups are effective. High % never destroyed

Symptomatic

Analgetics, antiflogistics

What are the prevention methods for Lyme disease?

Antiparasitic. Decrease population of ticks and micromammals. 

Immunoprophylaxis – monovalent, polyvalent, inactivated, subcellular

What is the aetiology for swine dysentery?

*Brachyspira hyodysenteriae, Brachyspiraa pilosicoli* - **Swine dysentery**

All ages, inflammation of large intestine, mortality due to dehydration 

*Brachyspiraa pilosicoli, B. inermedia, B. alvinipulli* – **Avian** (replicate in cecum)

What is the epizootiology for Brachyspira?

Transmission – oral faecal, direct, or indirect. Infected due to weak immune response. Spread also by insects, rodents, birds, dogs, and cats. Survive 8 w in cold environment

What is the incubation period for Brachyspira?

2-14 days

What are the clinical signs caused by Brachyspira?

Fever, depression, abdominal pain, dehydration, bloody diarrhoea, can be sub clinically. Chronic stage may develop with high economical losses

What is the diagnosis for Brachyspira?

CS, examination, isolation of bacteria, serology, PCR

Histopath, culture with beta haemolysis on blood agar under anaerobic conditions

What is the treatment for Brachyspira?

ATB – lincomycin and tylosin

What is the aetiology for syphilis?

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*Treponema paraluiscuniculi* – rabbit syphilis 

*Treponema paraluisleporis*

*Treponema porcinum* 

*Treponemma ruminis* 

What is the epizootiology of syphilis?

In some rabbits the bacterium may remain dormant for long periods of time, even years, and the affected rabbit will show no clinical signs until a stressful event occurs, causing the infection to erupt

What is the transmission for syphilis?

Mainly transmitted by **coitus**, but has also been seen in rabbits living singly, having had no contact with other rabbits (probably transmitted indirect through **the milk** from an infected doe to her offspring). **Horizontally and vertical transmission**

What are the clinical signs of syphilis?

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Typically affects the **mucocutaneous junctions of the genitalia, the anus and/or the face**. The skin becomes **crusty and ulcerated**; secretion of a pus-like exudate and bleeding can occur. Due to slow immune response to the bacterium, the infection can spread to the surrounding areas. 

Atypical form: clinical signs are seen **only on the face**. The affected area will exhibit lesions that will develop into crusts and, if left untreated, will spread. The lesions may become raw, inflamed, or may bleed.

What is the diagnosis for syphilis?

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Serology, PCR, **microscopy in dark field**, **VDRL slide test**

What are the differential diagnostics for syphilis?

Skin lesions, dermatomycosis, ectoparasites

What is the treatment for syphilis?

penicillin

What is the prevention for syphilis?

No vaccine, zoo hygiene, quarantine, natural breeding