Lecture 19: Francisella, Morexella, and Taylorella spp.

What are the characteristics of Francisella tularensis?

• Gram _

• Motility?

• Shape?

• Respiratory Pattern?

• Unique requirement?

• Gram -

• Non-motile

• Capsulated coccobacilli

• Obligate Aerobe

  • Therefore oxidase +

• Requires cysteine for growth

Is Francisella tularensis a notifiable disease?

• Yes!!

  • It is a nationally notifiable disease in the US and Canada

  • Also a CDC category-A biological/bioterrorism agent

How well does Francisella tularensis survive in the environment? Can it be killed via cleaning?

• 3-4 months in mud, water or dead animals 

• 3 years in frozen meat

• Easily killed via disinfectants or heat

Francisella tularensis causes _______ a zoonotic, plague like disease

Tularemia

What are the reservoirs of Francisella tularensis?

1° reservoirs are rodents and Lagomorphs

What are the vectors of Francisella tularensis?

• Ixodid ticks

• Mosquitos

• Deer fly

What are the main animals that Francisella tularensis affects?

1. Dogs

2. Cats

3. HJumans

Francisella tularensis is _______ in the US, where is it most common?

• Endemic

  • South-Central U.S and Martha’s Vineyard

How does weather play a role in the spread of Francisella tularensis subspecies tularensis?

There are significantly higher cases during years with increased rainfall

What are the routes of infection of Francisella tularensis subspecies tularensis?

• Arthropod bites

• Respiratory tract

Franscisella tularensis requires what for growth?

Cysteine

Francisella tularensis subspecies tularensis is a _____ pathogen

Primary Pathogen

What is the difference between Francisella tularensis subspecies tularensis and Francisella tularensis?

Francisella tularensis subspecies tularensis is the most virulent strain 

How does Francisella tularensis present grossly?

• Acute Septicemia

• Microabscesses and pyogranulomas

How does humans get infected with Francisella tularensis (Tularemia)?

• Skin contact/insect bite

• Ingestion

• Inhalation

T/F: Tularemia can be spread human to human

False

How do you treat Tularemia?

Antibiotics (Streptomycin)

T/F: Recovery from a Tularemia infection does not provide life-long immunity

True

How can Tularemia be prevented in dogs/cats?

• Tick control

• No unsupervised outdoor roaming

Moraxella bovis causes ____ ___ in cattle

Pink Eye (Infectious Bovine Keratoconjunctivitis (IBK))

What are the characteristics of Moraxella bovis?

• Gram _

• Respiratory pattern?

• Morphology

• Unique feature?

• Gram -

• Strict Aerobe

• Short paired rods (diplobacillus)

• Narrow zone of complete hemolysis and don’t grow on Maconkey

What animal acts as a mechanical vector for Moraxella bovis? (Use hint if needed)

Flies

T/F: Moraxella bovis can infect other ruminants

False, it is an obligatory pathogen of cattle

IBK presents _____ (answer with a timeframe) and is very contagious

Acutely

T/F: Moraxella bovis can cause permanent blindness

True

Which age range of cattle are most susceptible to Moraxella bovis?

Calves, they don’t have pre-existing immunity

What factors would pre-dispose cattle to Moraxella bovis?

• Viral infections

• Physical trauma

• UV light damage/Chemical Trauma

• Stress

Moraxella bovis can survive for up to 72 hours in the _______ organs of cattle

Salivary organs

What are the virulence factors of Moraxella bovis

1. Q-Fimbrae

   1. Aids in colonization

2. I-Fimbrae

   1. Local persistence

3. MBxa Haemolysin (RTX Toxin)

   1. Haemolytic and cytotoxic causes breakdown of collagen matrix of cornea

Strains of M. bovis that lack cytotoxin of fimbriae are _______

avirulent

If a cow is deficient of the lysozyme in lacrimal secretions, how does that affect its susceptibility/resistance to Moraxella bovis?

It makes it more susceptible

What are the C.S of Moraxella bovis?

1. Stage 1

   1. Excessive lacrimation, conjunctivitis, sensitivity to light 

   2. Small ulcer

2. Stage 2

   1. Ulcer spreads across the cornea

   2. Cornea becomes more cloudy

   3. Blood vessels make the cornea appear “pink“

3. Stage 3

   1. Ulcer covers most of the cornea

   2. Inflammation spreads to the inner eye

   3. Inside of eye fills with fibrin

4. Stage 4

   1. Ulcer completely extends through the cornea

   2. Eye is now blind 

What is the difference between summer and winter pinkeye?

• Summer pinkeye

  • Caused by M. bovis and or M. bovoculi

• Winter pinkeye

  • Mainly M. bovoculi

Winter pipnkeye can be confused with IBR, what is a distinguishing factor between the 2?

IBR doesn’t cause corneal ulcers like Moraxella bovis does

T/F: Moraxella bovis has little to no economic impact on the cattle industry

False, it costs over 150 million per year

How is Moraxella bovis diagnosed?

• Collect a lacrimal secretion

  • Test via…

    • Fluorescent antibody test (FAT)

    • Culture/identification

    • PCR

How can Moraxella bovis be controlled?

• Insect/fly control

• Manure control

• Pasture management

What disease causes pinkeye (IBK) in sheep/goats?

Moraxella ovis

Taylorella equigenitalis is found where?

The genital tract of stallion, mares, foals

Taylorella equigenitalis causes what disease?

• Contagious Equine Metritis (CEM)

  • Contagious Equine Uterus Inflammation

Taylorella equigenitalis usually causes a ____-_____ infection in mares

• Self-Limiting

  • Mucopurulent vaginal discharge in mares 2-14 days after breeding

T/F: Taylorella equigenitalis can cause permanent infertility in severe cases

False

T/F: CEM is zoonotic

False

What is the difference in infection of Taylorella equigenitalis between Thoroughbred and Non-thoroughbred breeds?

• Thoroughbred

  • Causes acute clinical disease

• Non-thoroughbred

  • Endemic and subclinical disease

What diseases does Taylorella equigenitalis cause in mares?

• Endometritis

• Cervicitis

• Vaginitis

T/F: Mares infected with Taylorella equigenitalis can transmit the infection to foals during birthing

True

T/F: Taylorella equigenitalis can cause abortions

True, but is uncommon

How is Taylorella equigenitalis tested for?

Testing is OIE-mandated

• Culture via federally approved labs

• qPCR

• Serology test in mares

• Test breeding of imported stallions

How can CEM/Taylorella equigenitalis be controlled?

• Test imported horses

• Topical disinfectant and antibiotic treatments to determine carrier state

• Removal from breeding

T/F: There is a vaccine for Taylorella equigenitalis (CEM)

False

Francisella tularensis is endemic worldwide, with wild rodent and lagomorphs as the reservoir hosts. T / F

True

Cats and dogs are not at risk of infection with F. tularensis. T / F

False

Transmission by face flies is the main cause of summer outbreaks of infectious bovine keratoconjunctivitis (pinkeye). T/ F?

True

Winter pinkeye outbreaks in cattle could be misdiagnosed as IBR infection. T /F?

True

Taylorella equigenitalis causes an acute suppurative endometritis in mares of all horse breeds. T / F

False, only in thoroughbred mares

Detection of CEM is difficult because it is endemic and non-clinical in nonThoroughbred breeds in many countries. T / F?

True