Flaviviruses and Louping Ill Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following is a principal vector for tick-borne encephalitis?

Dermacentor variabilis

Ixodes ricinus (correct)

Rhipicephalus sanguineus

Amblyomma americanum

What is one potential method of transmission for tick-borne encephalitis?

Human-to-human transmission

Inhaling infected droplets

Direct contact with infected blood

Consumption of raw goat milk (correct)

Which animals are primarily susceptible to tick-borne encephalitis?

Humans and domesticated mammals (correct)

Insects and arachnids

Fish and birds

Reptiles and amphibians

What describes the natural cycle of tick-borne encephalitis?

Rodents and small mammals Signup and view all the answers

Which lineage of tick-borne encephalitis is endemic in Central Europe?

Central-European lineage Signup and view all the answers

Which genus of flavivirus includes the majority of exotic species with weak resistance?

Orthoflavivirus Signup and view all the answers

What is a major clinical sign associated with louping ill?

Biphasic fever Signup and view all the answers

What is the principal vector responsible for the transmission of louping ill?

Ixodes ricinus Signup and view all the answers

Which of the following diagnostic methods is NOT used for louping ill?

X-ray imaging Signup and view all the answers

What type of vaccine is available for louping ill in endemic countries?

Inactivated vaccine Signup and view all the answers

Which symptom indicates possible permanent harm after recovery from louping ill?

Ataxia Signup and view all the answers

Which of the following ways is NOT known for potential transmission of louping ill to humans?

Direct contact with infected animals Signup and view all the answers

What is an important histopathological finding in cases of louping ill?

Lymphocytic encephalitis Signup and view all the answers

What is the typical incubation period for tick-borne encephalitis in humans?

1-2 weeks Signup and view all the answers

Which clinical sign is not typically associated with tick-borne encephalitis in animals?

High fever Signup and view all the answers

What is the first sign of tick-borne encephalitis in humans?

Fever and influenza-like disease Signup and view all the answers

Which of the following is a method for the direct diagnosis of tick-borne encephalitis?

RT-PCR Signup and view all the answers

Which prevention method is suggested for tick-borne encephalitis?

Inactivated vaccine Signup and view all the answers

What might be a long-term consequence of tick-borne encephalitis?

Permanent brain lesions Signup and view all the answers

Which of the following is considered a differential diagnosis for tick-borne encephalitis?

Flaviviruses Signup and view all the answers

Which clinical signs are rarely observed in animals affected by tick-borne encephalitis?

Increased appetite Signup and view all the answers

What percentage of horse infections with West Nile fever are typically subclinical?

80-90% Signup and view all the answers

Which clinical sign is NOT commonly observed in infected geese?

Loss of appetite Signup and view all the answers

Which of the following animals shows a less severe reaction, often being asymptomatic or having rare CNS signs?

Dog Signup and view all the answers

What is a characteristic histopathological finding in horses infected with West Nile fever?

Neuronal cell degeneration Signup and view all the answers

What is one of the main methods used for diagnosing West Nile fever in a laboratory?

RT-PCR Signup and view all the answers

What percentage of lethality is observed in geese infected with West Nile fever?

14-40% Signup and view all the answers

Which of the following statements about wild birds infected with West Nile fever is true?

Can exhibit asymptomatic infections Signup and view all the answers

Which sign is a specific indicator of West Nile fever in sheep?

Teeth grinding Signup and view all the answers

What percentage of West Nile fever infections in horses are typically subclinical?

80-90% Signup and view all the answers

What are the general clinical signs of West Nile fever in horses?

Febrile general signs, anorexia, and depression Signup and view all the answers

Which of the following CNS signs is NOT associated with West Nile fever in horses?

Severe skin rashes Signup and view all the answers

Which animal shows teeth grinding and ataxia as clinical signs of West Nile fever?

Sheep Signup and view all the answers

What is the lethality percentage range associated with West Nile fever in horses?

9-90% Signup and view all the answers

In which age group of geese is West Nile fever most likely to present with seizures and ataxia?

3-12 weeks of age Signup and view all the answers

What type of clinical response do dogs and cats typically show when infected with West Nile fever?

Asymptomatic seroconversion and rarely fever Signup and view all the answers

Which CNS sign is common among geese affected by West Nile fever?

Wing paralysis Signup and view all the answers

Study Notes

Flaviviruses

Flaviviridae family: enveloped, icosahedral, positive-sense RNA viruses
Orthoflavivirus, Pestivirus, and Hepacivirus genera
Orthoflavivirus genus:
- 53 species, mostly exotic with specific geographic distributions
- Weak resistance to various factors (pH, high temperatures, detergents, disinfectants)
- Transmission through ticks, mosquitos, or non-vectorial routes (airborne, oral)
- Broad host range, many are zoonotic
- Common symptoms: fever, rash, encephalitis, meningitis, hemorrhage
- Strong antigens, cross-reactions, and sometimes cross-protection between different strains

Louping Ill

Tick-borne febrile illness with neurological complications in sheep and rarely other animals
Occurrence: British Isles, Scandinavia, Spain, Greece, Turkey
Main vector: Ixodes ricinus tick, causing seasonal outbreaks
Susceptible animals: sheep, domestic and wild mammals, red grouse, humans
Clinical signs:
- Incubation period: 1-3 weeks
- Biphasic fever
- Depression, salivation, tremors, convulsions, tics
- Ataxia (hallmark of the disease)
- Coma, death
- Frequent permanent neurological damage after recovery
- Transmission through milk, infecting young animals
Histopathology: lymphocytic encephalitis, neuron necrosis, glial cell proliferation

Louping Ill Diagnosis

Based on: epizootiology, clinical signs, histopathology
Laboratory methods: isolation, RT-PCR, serology (HI, VN, ELISA)

Louping Ill Differential Diagnosis

Listeriosis: distinguish through histopathology and bacteriology tests
Rabies: consider geographic occurrence, clinical course, and laboratory findings
Scrapie: consider geographic occurrence, distinct clinical course (no fever), and laboratory results

Louping Ill Prevention

Tick control measures
An inactivated vaccine is available in endemic regions

Public Health Considerations for Louping Ill

Human infection is rare
Transmission: tick bite, airborne, oral

Tick-borne Encephalitis (TBE)

Human febrile illness with potential meningo-encephalomyelitis
Two main lineages: Central European and Far Eastern
Endemic in Central Europe, with focal infections
Main vector: Ixodes ricinus tick (Ixodes persulcatus in Asia)
- Biological vector, transovarial transmission
Susceptible animals: humans, domestic and wild mammals, birds
Natural cycle: rodents, small mammals (and birds) - ticks
Human and animal infections:
- Seasonal tick bite transmission
- Consumption of unpasteurized goat milk (reported events in Hungary from 1955-2008)
Pathogenesis: infection, local multiplication, viraemia, visceral organs, central nervous system

Tick-borne Encephalitis Clinical Signs

Often subclinical in animals, frequently subclinical in humans
Incubation period: 1-2 weeks
Two-phase illness:
- Initial fever and influenza-like symptoms
- Second fever 7-10 days later with CNS signs: headache, restlessness, stiff neck, weakness, paralysis
Usually complete recovery, but permanent neurological damage can occur
Rare clinical signs in foals, dogs, and goats: depression, ataxia, convulsions, tremors

Tick-borne Encephalitis Diagnosis

Direct methods: isolation (suckling mouse brain), RT-PCR, hemagglutination
Indirect methods: immunofluorescence, ELISA, HI, VN (PRNT)

Tick-borne Encephalitis Differential Diagnosis

Enteroviruses, togaviruses, flaviviruses, herpesviruses, bacterial meningitis

Tick-borne Encephalitis Prevention and Control

Prevention of tick bites
Inactivated vaccine: 2 doses followed by a booster 3-4 years later

West Nile Fever

Mosquito-transmitted zoonotic disease
Symptoms: fever, general signs, sometimes meningo-encephalomyelitis, and death

West Nile Fever Occurrence

First isolation: Uganda in 1937 (human encephalitis) - named West Nile Virus (WNV)
Worldwide distribution

West Nile Fever Pathogenesis

Transmission through mosquito bites
Birds are primary reservoir hosts, amplifying the virus
Persisting infections are rare in mammals, frequent in birds

West Nile Fever Clinical Signs

Horses:
- 80-90% of infections are subclinical
- Fever, general signs, anorexia, depression
- West Nile Neurologic Disease (WNND) < 1%: skin sensitivity, hind limb weakness, teeth grinding, convulsions, seizures, incoordination, aimless wandering, circling, paralysis, coma
- Lethality: 9-90%
Sheep: teeth grinding, ataxia
Dogs and Cats: asymptomatic seroconversion, rarely fever, CNS signs
Geese:
- Age 3-12 weeks: seizures, ataxia, abnormal head position, wing paralysis
- Lethality: 14-40%
Wild Birds: storks, birds of prey, crows, magpies, sparrows, seagulls, blackbirds, etc
- Asymptomatic infection or death
- Asymptomatic seroconversion, seizures, ataxia, paralysis, sudden death
- Can be key indicators for outbreaks

West Nile Fever Pathology

Horses and birds:
- Petechial hemorrhages (pericardium, muscles)
- Serous fluid accumulation in the epicardium
Histopathology (horses, birds):
- CNS: multifocal cellular infiltration, hemorrhages, neuron cell degeneration, apoptosis, glial cell proliferation
- Myocardium: serous-cellular inflammation, cell degeneration, apoptosis

West Nile Fever Diagnosis

Differential diagnosis: from other febrile illnesses with CNS signs
Epizootiology and clinical signs: seasonal (midsummer to fall), suspicion of infection if CNS signs occur
Laboratory diagnosis:
- RT-PCR
- Virus isolation (suckling mouse brain, Vero cell line, embryonated egg, early stages of infection, BSL3 laboratory)
- Immunohistochemistry (successful in ~ 50% if death occurs within 1 week)
- Serology (cross-reactions possible)

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the characteristics of Flaviviridae family viruses, including their genera and transmission routes. Learn about Louping Ill, a tick-borne disease affecting various species, its distribution, and clinical signs. This quiz delves into the complexities of these significant pathogens.