Flashcards in Lecture 16 Deck (82):
types of non enveloped RNA viruses
polio virus, coxsaki virus, Hepatitis A, Rhino virus, Rota virus
Types of enveloped RNA viruses
influenza, measels, mumps, rubella, rabies, retro virus (HIV, HTLV)
What does Influenze virus cause?
3 serological types of influenza
A, B, C
Define envelop of influenza virus
has two types of spikes- hemaglutinin & Neuraminidase- the envelop protein determines type specificity
Other name for influenza virus
orthomyxovirus which interacts with mucin and has an 8 segmented genome
What is the present strain causing swine flu?
Who is the influenza A virus present in?
humans- also in birds, chicken, sqine and horses-- sources for antigenic shift and pandemics
Who is the influenza B virus present in?
Transmission of influenza
air born- respiratory droplets- group A- antigenic shift every 10/11 years- group B is antigenic shift yearly
When does the infection of influenza occur?
in winter months; restricted respiratory tract- systemic symptoms ar not due to viremia
What are systemic systems of influenza due to?
due to circuating cytokines
What gives immunity to influenza?
clinical features of influenza
24-48 hours-- will have fever, myalgia, sore throat, cough- sudden onset. Resolves spontaneously in 4-7 days
Treatment for influenza?
Zanamvir & Tamiflu- inhibits release of virus from cell- effective against A and B
Amantadin effective against A
What is the natural host of Measles
single serotype- humans are the natural host
Transmission of Measles
transmission by respiratory droplets- world wide distribution-
What stage is Measles highly contagious in?
prodromal stage- non infectious after development of rashes- cough and sneezing spread disease
How often does the Measles epidemic occur?
once in 2-3 years
Clinical features of Measles?
fever, photophobia, runny nose and cough- red spot with white center on buccal mucosa of oral cavity
Define development of rash in Measles
rashes develop on face and then spreads downwards- become brownish several days later
What affect can measles have on pregnant women?
still births in pregnant women- affords life long immunity
Complications of measles
encephalitis- very rare
Sub acute schlerosing Pan- can develop years later but rare
Lab diagnosis for Measles
NONE- diagnosed on clinical grounds
Is there an antiviral drug for Measles?
Prevention of Measles
live attenuated vaccine- given at 15 months or later because before then vaccine will have no effect because maternal Abs still present
single sero type- infects URT and blood spreads to parotid gland, testes, ovaries, pancreas and sometimes meningitis
Can you get mumps more than once?
How is mumps transmitted?
through respiratory droplets- world wide distribution- peak incidence in winter
What percentage of children have mumps without symptoms and are therefore immune?
Clinical manifestations of Mumps
18-21 days- fever, malaise, followed by tender swelling in parotid gland- disease is benign- resolves spontaneously
Complications of mumps
If the disease occurs in post pubertal males, it can cause orchitis which may cause infertility
Medication for mumps
NONE- prevention through MMR vaccine
What does respiratory syncytial virus cause?
pneumonia and bronchiolitis in infants
What is on the surface of the virus for respiratory syncytial virus?
fusion proteins only- no hemaglutinin/neuraminidase
natural host of respiratory syncytial virus?
humans and chimpanzees
Transmission of respiratory syncytial virus
respiratory droplets/direct contact with nose and mouth by finger- outbreaks occur every winter world wide- everyone infected by age 3
Clinical features of respiratory syncytial virus?
bronchiolitis, pneumonia, otitis media in young children. In adults it causes common cold
Treatment of respiratory syncytial virus?
Aerosolised Ribovirin in severe infections- no vaccine available
What does Para Influenza virus cause?
CROUP- acute laryngo tracheo bronchitis inc hildren
Transmission of para influenza
respiratory droplets- world wide in winter
What do the majority of para influenza cases cause?
sub clinical infection- no antiviral drug or vaccine (self limiting)
What does Rubella virus cause?
German measles - single serotype
Transmission of Rubella virus
respiratory droplets, placental transmission from mother to fetus
How often does epidemic of rubella virus occur?
every 6-9 year
Clinical manifestation of rubella
milder and shorter disease- causes fever, malaise, followed by rashes from face to trunk and limbs- lymph node enlargement behind ear lobe
How often do rashes from rubella last?
3 days then disappear
What happens if rubella occurs while a woman is in her first trimester?
teratogenic effect in infants- heart, eye, and brain will be affected, causing cataract, deafness, mental retardation, PDA (Rubella syndrome) - these children excrete viruses for a long time
Shape of virus for rabies?
bullet shaped virus- single antigenic type
mammals, skunks, raccoons, bats and dogs
How do humans get infected with rabies?
through animal bite- non bite transmission through respiratory aerosol from bats secretion
How does the rabies bite affect the body?
moves from bite site to CNS: multiplies in brain tissue and then spreads through peripheral nerves to salivary glands- encephelitis in brain
Any immunity for rabies?
NO- because no survivors
Clinical manifestations of rabies
infectious for 2-16 weeks- shorter time if site is near to head- prodromal symptoms, fever, anorexia, confusion, lethargy, increased salvation
within a few days goes into coma and dies
Diagnosis of Rabies
negri bodies can be demonstrated from corneal scrapings and autopsy specimen - no antiviral drug
Prevention of rabies
pre exposure, immunization with rabies vaccine to vets and zoo keepers
Can a rabies vaccine be given after infection?
How do you treat rabies bite?
wound should be cleaned and cauterized
If rabies symptoms develop in animal what is done?
What does Polio virus cause?
poliomyelitis in children
Host of Polio Virus?
Primates (Apes and Monkeys), man
Discuss serotypes of Polio
3 serological types- protection requires vaccine for all three types
Transmission of Polio
by fecal-oral route: replicated in oro-pharynx and intestinal tract
Pathogenesis of POlio
after replication, it spreads through blood to CNS- infects motor neurons in ventral horn of spinal cord- death of neurons results in paralysis
Immune response for polio
intestinal IgA, humoral IgG
Clinical features of polio?
mostly asymptomatic- only 1% of infection manifests symptoms
brief fever, patient develops flaccid paralysis of one or both limbs, motor nerve degeneration is permanent
For how long does patient excrete polio virus in feces?
Prevention of polio
2 vaccines available
killed vaccine- IPV
live vaccine- OPV
3 doses given once monthly
What are the 2 groups of Coxsackie virus?
A - infects skin and mucous membranes
B- infects internal organ
How is Coxsackie virus transmitted?
Where does Coxsackie virus replicate?
oropharynx and GIT- common in summer
Clinical manifestations of Group A Coxsackie virus?
Herpangina- fever, sore throat, vesicles in oral cavity; acute hemmorrhagic conjunctivitis; foot and mouth disease
What is Foot and mouth disease?
rashed in hand, foot and ulcerations in the mouth- children
Clinical manifestations of Group B Coxsackie virus?
Pleurodynia- fever, with severe pleuritic chest pain; myocarditis and preicarditis- fever, chest pain, CCF
Vaccine for Coxsackie virus?
NO- and no antiviral drug
What does rhino virus cause?
common cold in winter months
host of rhino virus
human and chimpanzees
Transmission of rhino virus?
aerosol, hands, fingers and towels
Clinical manifestations of rhino virus
sneezing, nasal discharge, sore throat, head ache and chilly sensation- lasts for a week
Is there a vaccine for rhino virus?
NO- can offer vitamin C in high doses, Zn gluconate lozanges
Transmission of rota virus?
fecal-oral route: common in children