Encephalitozoonosis and nosematosis. Flashcards
(23 cards)
microsporida is
Obligate intracellular protozoan parasites
What is the final host of Encephalitozoon cuniculi?
rabbit
location of Encephalitozoon cuniculi
Brain, kidneys
Encephalitozoon cuniculi - transmission
Through urine and transplacental transmission, ingestion of spores
Encephalitozoon cuniculi - life cycle
1) The infective form is a Resistant Spore, which can survive for a long time in environment.
2) FH eats spores through feces
3) The spore extrudes its polar tubule and infects the host cell in the intestines
4) The spore injects the infective sporoplasm into the eukaryotic host cell through the polar tubule
5) Inside the cell, the sporoplasm undergoes extensive multiplication either by binary fission or multiple fission (merogony or schizogony).
6) Sporogony produce the infective form (spore)
Encephalitozoon cuniculi - pathogenesis
A chronic, usually latent disease of rabbits characterised mainly by damage to the nervous system and kidneys, diarrhoea and respiratory symptoms (bronchitis, pneumonia or sinusitis).
ZOONOSIS!
3 main manifestations:
Neurological - central vestibular dysfunction (hearing dysfunction) –> head tilt, torticollis, tremor, circling, ataxia, nystagmus, seizures, asthenia, paresis, limb paralysis, urinary incontinence
Renal - chronic interstitial nephritis, polyuria/polydipsia, dehydration
Ocular - phacoclastic uveitis (lens trauma), uveitis, white intraocular lesions, cataract
Non-specific - anorexia, weight loss
Death
Multifocal depressions: granulomatous inflammation, scarring of renal interstitium
Organisms in pseudocyst: renal tubule epithelium, ruptures –> inflammation
Focal granulomas in brain
Encephalitozoon cuniculi - CS
Non-specific neurological signs
- convulsions, tremors, head tilt - torticollis
Encephalitozoon cuniculi - DX
Light microscope, electron microscopy, IFA, PCR
Encephalitozoon cuniculi - TX
- Fenbendazole (also in dogs)
- Albendazole (also in dogs)
- Pyrimethamine
- Supportive
- Surgery: remove lens of eye, enucleation
- Humans: albendazole
Encephalitozoon cuniculi - prevention
Serological screening
Separation of seropositive animals
Screening of new animals
Preventive fenbendazole for rabbits at risk
Cleaning and disinfection
Personal hygiene
Encephalitozoon cuniculi - Encephalitozoonosis in dogs is an opportunistic infection, meaning it is only clinically manifested when:
immune system is weakened, or Transplacental infection
Encephalitozoon cuniculi - dx in dogs
Difficult as even healthy dogs can be antibodies
Clinical signs
Spores in urine
Post-mortem granulomas in tissues
Nosematosis is a disease of what species?
honey bees
- Varimorpha ceranae (Nosema ceranae)
- V. apis (N. apis)
What is the route of infection for Varimorpha ceranae?
fecal oral
What is the location of V. ceranae?
honey bee intestine
Encephalitozoon species
E. cuniculi
E. intestinalis
E. hellem
E. lacertae
Describe the morphology of Varimorpha ceranae and V. apis:
Spores (difficult to distinguish)
V. ceranae: smaller spores, 20-23 polar filaments
V. apis: spores have 30-44 polar filaments
Describe the life cycle of Varimorpha:
1) FH (bees) are infected by ingestion of food containing spores
2) Spores in midgut lumen —> spore germinate —> polar filaments everts and pierce midgut epithelial cell
3) Sporoplasm is injected to the cell’s cytoplasm
4) Merogony: sporoplasm develops into meront —> multiply by binary fission inside cytoplasm of midgut epithelial cell
5) Sporogony: Proliferative stage –> sporonts –> sporoblasts —> spore formation —> mature spores
6) infected cell ruptures; spores released into gut —> Spores released in feces
What are the clinical symptoms of Nosematosis?
Enlarged abdomen of worker bees
Brown fecal marks on comb
Reduced brood production
Slow growth of colony
Unable to produce queen jelly
Production of mature larvae decreases
Stop caring for offspring and turn to foraging
Infected queen stop laying eggs
Shortened life span
Dysentery (V. apis)
100% mortality 10-14 days
Describe the pathogenesis of Nosematosis?
Changes in sugar metabolism
Changes in hormone levels and pheromone production
Shortened life span
Change in flight activity
Reduced success in returning to hive stable
Loss of bees in colony
Faster conversion of honey bees to foraging - change in polyethism (division of labour)
Coexistence with other pathogens - increased mortality
How do we diagnose Nosematosis?
Histopathology
Microscopy: light, TEM
Fluorescense microscopy
PCR
LAMP
Analysis of environmental DNA in honey
How do we treat Nosematosis?
Oxytetracycline
Fumagillin
- side effects: digestive problems, decreased immune system
Natural: organic acids, polysaccharides, essential oils, microorganisms
How can we prevent Nosematosis?
New queen bee
Control of other parasites
Avoid chronic exposure to pesticides or acaricides
