Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
24 Cards in this Set
- Front
- Back
|
Arbovirus Definition: “Arthropod-borne” virus
Virus cycles between _____ and ________ host Only three arboviruses for which humans are a primary vertebrate host: (3) Most other arboviruses that infect humans have other primary hosts (humans infected incidentally) - Example? Usual insect vectors: (3) |
Viruses that are maintained in nature by a transmission cycle between susceptible vertebrate hosts and arthropods
Only three arboviruses for which humans are a primary vertebrate host: dengue, yellow fever, and Chkungunya viruses (possible explosive urban epidemics) Most other arboviruses that infect humans have other primary hosts (humans infected incidentally) - West Nile virus: birds Usual insect vectors: mosquitoes, ticks, fleas |
|
|
What is the number one mosquito borne arbovirus of the world?
What is the most clinically important form of this disease? |
Dengue
Dengue Hemorrhagic Fever |
|
|
Globally Important Arboviruses
Dengue Fever (DF) /Dengue Hemorrhagic Fever (DHF) Transmitted by which type of mosquito? Cycle? Incubation? If you don't have manifestation within __ weeks, you don't have dengue fever How many serotypes? Sequential infection can lead to ______ risk of ___ DF: Symptoms? DHF: Symptoms? Treatment? |
- Transmitted by Aedes aegypti mosquito
Human-mosquito-human cycle: 2-10 day incubation If you don't have manifestation within 2 weeks, you don't have dengue fever 4 serotypes of DV (DV1, DV2, DV3, and DV4) Sequential infection can actually lead to augmented 2nd infection: increased risk of DHF DF: “Breakbone fever” -- Fever, rash, HA, severe myalgia, arthralgia DHF: Shock/DIC picture: DF + thrombocytopenia + bleeding No treatment, (vaccine in clinical testing - phase I/II) |
|
|
West Nile Encephalitis Virus - Epidemiology
Transmitted how? Virus carried by? Sign that virus is in area? ____ begin to die Elderly or immunocompromised patients progress to ________ or ________ |
Mosquito transmitted
Migratory birds carry virus: hawks, jays, crows (in US virus kills birds - especially crows- not seen in old World) ~27,000 symptomatic human cases in US Elderly or immunocompromised patients progress to aseptic meningitis or encephalitis |
|
|
West Nile Virus Transmission
Cycle: Normally transmitted between _____ and ______ Can _________ be transferred to many types of mammals, including humans Transmission occurs to humans from mosquitoes by _________ When ______ (type of bird) leave late summer/early fall, mosquitos start to infect humans |
Normally between birds and mosquitoes
Can incidentally be transferred to many types of mammals, including humans Transmission occurs to humans from mosquitoes by direct inoculation |
|
|
West Nile Virus Epidemiology
~__ cases of meningoencephalitis per 140 infections Higher risk in age > ___ Genetic susceptibility: CCR5-32, OAS1b CCR5-32 deletion confers resistant to _____; but increased susceptibility for severe WNV infection |
~1 case of meningoencephalitis per 140 infections
Higher risk in age > 55 Genetic susceptibility: CCR5-32, OAS1b CCR5-32 deletion confers resistant to HIV; but increased susceptibility for severe WNV infection |
|
|
Clinical Features of WNV Infection
- _-__ day (~_ weeks) incubation period post mosquito bite - Typical case is ___(mild/severe?): (4) (symptoms last 3-6 days) - Occasional ________ ____ (trunk>extremities) (rare in US cases) - In elderly or patients with co-morbidities, may progress to (3) - Virus infects and kills ________ _____ ______ neurons; may resemble _____ - Rare complications include (2) |
- 5-15 day (2 weeks) incubation period post mosquito bite
- Typical case is mild: fever, HA, myalgia/arthralgia, anorexia (symptoms last 3-6 days) - Sore throat and GI complaints (N/V/D) may occur - Occasional maculopapular rash (trunk>extremities) (rare in US cases) - In elderly or patients with co-morbidities, may progress to aseptic meningitis, encephalitis, flaccid paralysis - Virus infects and kills anterior horn motor neurons; may resemble polio - Rare complications include myocarditis and pancreatitis |
|
|
West Nile Virus -Prognosis
- Recovery is usually ________ in __________ patients - ____ (more/less) rapid recovery in adults compared to children, occasionally with residual deficits - Of hospitalized patients, __% recovered but not to full functional level whereas __% recovered fully - Most fatalities in patients > __ y.o. |
- Recovery is usually complete in non-hospitalized patients
- Less rapid recovery in adults compared to children, occasionally with residual deficits - of hospitalized patients, 50% recovered but not to full functional level whereas 40% recovered fully - Most fatalities in patients > 50 y.o. |
|
|
West Nile Virus Laboratory
Diagnosis: - Serum Ig_ or paired Ig_ samples for immunoflourescence a) Problem: cross reactivity with __________ ? - Which lab is diagnostic? Sensitivity IgM (acute serum & CSF): __% IgG (paired acute/convalescent sera): __% (basically, which is more sensitive?) RT-PCR: ___ (high/low) sensitivity when viremic (short period) |
Diagnosis
- Serum IgM or paired IgG samples for immunoflourescence a) Problem: cross reactivity with other flaviviruses (St Louis, dengue, yellow fever - travel and vaccination history required) - CSF IgM (Diagnostic for WNV) - Serum or CSF RT-PCR for viral RNA Sensitivity IgM (acute serum & CSF): 70% IgG (paired acute/convalescent sera): 90% RT-PCR: high sensitivity when viremic (short period) Nucleic acid based amplification assays |
|
|
West Nile Encephalitis - Therapy and Vaccine
How do you treat West Nile Encephalitis? |
All therapies are investigational
Vaccines: Investigational - Killed (horses, birds - experimental) - Chimeric Yellow Fever or Dengue strain - Recombinant protein vaccine - E protein - Attenuated Strain Vaccine - WNV 25 Vaccine issues: low frequency disease, side effects of immunization of large population |
|
|
Chikungunya Virus
Chikungunya stands for - Viral disease transmitted by? - Virus Family? Genome? - Causes? (symptoms) - Treatment? - Course? - Mutations? |
Chikungunya = contorted posture of patients with severe joint pain
- Viral disease transmitted by Aedes mosquitoes - Member of Alphavirus family of RNA viruses (different from flavivirus) - Causes a debilitating febrile illness (rash/joint pain/encephalitis) - No vaccine/treatment - Acute disease (lasts a few weeks); arthritis can take weeks/months to resolve due to long lasting inflammatory process - Adaptive mutation (inc. amount of virus that replicates for longer period of time in mosquito host and inc. virulence in mammalian host) has led to explosive epidemics including recent disease in Italy - Chikunugunya infection in returning US travelers - Outbreaks: India, Indonesia, Malaysia, Singapore, Sri Lanka,Italy (1.3 million cases in India in 2006 alone) |
|
|
Enterovirus Epidemiology
Family? Envelope? Serotypes? Most infections are ____: manifestations = (2) Some cause ____ disease: manifestations = (4) Some cause chronic diseases: (3) |
Belong to Picornaviridae family of RNA viruses
Non enveloped (important for why they spread easily) Composed of more than 70 serotypes (1 set of Ab won’t protect as well as others) Most enterovirus infections are mild - Upper Respiratory Infection and febrile rash Some cause severe disease: (heterogeneous) - encephalitis, myocarditis, neonatal sepsis, polio Some cause chronic diseases (heterogeneous) -myocarditis, cardiomyopathy, neuromuscular disease |
|
|
Enterovirus Epidemiology
Enterovirus epidemics predominate in _____ and _____(seasons?) ________ most likely to be affected Most common age group: _-_ years old: Due to: increased reporting bias; lack of cross-reactive immunity daycare exposure Transmission mainly ____-____; also? (1) Reservoirs? |
Enterovirus epidemics predominate in summer and fall
Young children most likely to be affected Most common age group: 1-4 years old Due to: increased reporting bias; lack of cross-reactive immunity daycare exposure Transmission mainly fecal-oral; also respiratory droplets No non-human reservoirs |
|
|
Epidemiology of Enterovirus Infections
One of the most important determinants is ___ - most primary infections occur during _________ _________ are most important for transmission cycle _______ have more severe disease Male:female ratio: ___ to ___ More prevalent in _________ and those living in _________ |
One of the most important determinants is age - most primary infections occur during childhood
children are most important for transmission cycle Adults have more severe disease Male predominance: 2 to 1 ratio More prevalent in persons of low socioeconomic status and those living in urban areas |
|
|
Steps in Enterovirus Pathogenesis
Describe the steps |
|
|
|
Vaccines: Polio as a Model - Global Eradication
With global incidence declining, CDC recommends exclusive use of _____-______ vaccine only - eliminates vaccine-associated paralytic poliomyelitis and shedding of vaccine virus ___ cases of paralytic polio in US since 1980 |
With global incidence declining, CDC recommends exclusive use of heat-killed vaccine only
- eliminates vaccine-associated paralytic poliomyelitis and shedding of vaccine virus No cases of paralytic polio in US since 1980 |
|
|
________ are the main recognized cause of aseptic meningitis in children and adults of developed countries
What type of virus? Suspect more during which sesons? What associated symptoms should you look out for? Diagnosis can be made with? |
Enteroviruses are the main recognized cause of aseptic meningitis in children and adults of developed countries
Coxsackievirus group B: isolated from 62% of infants (< 3mo) with aseptic meningitis Should be suspected as the causative agent of aseptic meningitis during the summer and fall seasons Rash may be present: Coxsackie A5, A9, A16; echovirus 4, 6,9 RT-PCR used in diagnosis - Coxsackievirus B5 - Echoviruses 4, 6, 9 and 11 - Enterovirus 71: emerging |
|
|
Enteroviruses and Respiratory Infections
Most frequently associated with URI (3) - _________ - ________ (inflammation of upper airway, bark like a seal) - ________ (can compromise airways) Severity: URIs tend to be ___ and _____ Rarely, can cause lower respiratory tract infection, such as _______ ________? |
Enteroviruses are a common cause of URI
Most frequently associated with URI - common cold - croup (inflammation of upper airway, bark like a seal) - epiglottitis (can compromise airways) URIs tend to be mild and self-limited Rarely, can cause lower respiratory tract infection, such as interstitial pneumonia |
|
|
Enteroviruses Cause Encephalitis
More severe and worse prognosis than ________: directly affects neurons Manifestations? (3) Can get ____ ________ syndrome: Increased incidence of Enterovirus ___: clinically fare worse; this strain is more virulent; case fatality rate of CNS infection ranges from 7 to 31% |
More severe and worse prognosis than meningitis: directly affects neurons
Altered mental status, focal neurologic signs, seizures Can get acute cerebellar syndrome: polio, echoviruses, coxsackie A2 and A9 Increased incidence of Enterovirus 71: clinically fare worse; this strain is more virulent; case fatality rate of CNS infection ranges from 7 to 31% |
|
|
Enteroviruses Cause Cardiac Disease
Acute Cardiac Disease Which Enterovirus is main culprit? Peak age group? Chronic Cardiac Disease Which type of heart disease? Which group most common? Virus isolated from specimen? Possible mechanism? |
Acute Cardiac Disease
Enteroviruses implicated as agent of viral myocarditis Coxsackievirus B5 main culprit; other strains implicated Peak age group: Young adults 20-39, increased males Chronic Cardiac Disease Implicated in sporadic dilated cardiomyopathy Coxsackievirus B group most common Virus not isolated from specimens Possible immunopathogenic mechanism (mimicry?) |
|
|
Enteroviruses Caues Eye Infections
What type of eye infection is most commonly caused by enteroviruses? Symptoms? Disease resolves in __ weeks? |
Acute hemorrhagic conjuctivitis – most commonly caused by enteroviruses
Excessive lacrimation, pain, periorbital swelling,redness, possible visual impairment Disease resolves in 1-2 weeks without sequelae Also sporadic conjuctivitis and keratoconjuctivitis |
|
|
Enteroviruses Cause Herpangina
Herpangina is? Characteristic lesions on the? May be as part of a constellation of ___-____-_____ disease: vesicular lesions of the hand, feet, mouth, Several enteroviruses associated with herpangina: ? |
Herpangina is a febrile illness of acute onset with fever and sore throat
Characteristic lesions on the anterior tonsils, soft palate, uvula, tonsils, and pharynx May be as part of a constellation of hand-foot-and-mouth disease: vesicular lesions of the hand, feet, mouth, Several enteroviruses associated with herpangina: coxsackie A/B, echoviruses, and enterovirus 71 |
|
|
Diagnosis of Enteroviral Infections
Std diagnostic tool? |
RT-PCR of viral RNA from clinical specimen
|
|
|
Therapy for Enteroviral Infections
? |
- There is no therapy
- Supportive care |
