viral (R-T) Flashcards
what is rabies virus? family / genus
family Rhabdoviridae
genus Lyssavirus
neurotropic = virus travels from bite along peripheral nerves to CNS, where viral replication increases exponentially
all mammals are susceptible to rabies, but which animals are major rabies virus reservoirs?
mesocarnivores and bats;
dogs in low-mid income countries
how are rabies virus classifed into 2 major genetic lineages?
canine
New World bat
what is the rate of rabies exposures in travelers?
16-200 per 100,000 travelers
when does signs and symptoms develop after rabies exposure?
weeks to months
what is the fist symptom of rabies?
pain and paresthesia at the site of exposure
what are the symptoms of prodromal phase and neurologic phase of rabies?
prodromal - fever, nonspecific, vague symptoms
neurologic - anxiety, paralysis, paresis, encephalitis, muscle spasm (stimulated by sight, sound, perception of water-hydrophobia), delirium, convulsions, coma, death
what % of people with rabies manifest with classic encephalitic disease? paralytic rabies?
80% - encephalitic
20% - paralytic
how to diagnose rabies?
definitive antemortem diagnosis - multiple specimens including CSF, saliva, serum, skin biopsies taken from the nape of the neck; sequential sample collection needed if antibody detection varies over the course of illness.
after the first symptom occurs, how soon does the rabies progress to coma/death?
7-10 days
how to treat rabies?
early and robust production of rabies virus-neutralizing antibodies
besides rabies virus, what are other bat-associated pathogens?
histoplasma spp., coronaviruses, viral hemorrhgic fever viruses
why pre-exposure prophylaxis is recommended for rabies?
- it simplifies PEP
- some protection when an exposure to rabies virus goes unrecognized, or PEP is otherwise delayed
what are 5 risk categories of rabis for people?
- elevated risk for unrecognized & recognized exposures, including unusual or high-risk exposures
- elevated risk for unrecognized and recognized exposures
- elevated risk for recognized exposures or sustained risk
- elevated risk for recognized exposure, no sustained risk
- low risk for exposure
for category 1 population for risk of rabies, who are typical population?
what is the dose for prEP?
people working with live virus in research or vaccine production facilities
people performing testing for rabies in diagnostic lab
0, 7 days; then check every 6 months (booster if <0.5IU/mL8)
for category 2 population for risk of rabies, who are typical population?
what is the dose for prEP?
people with frequent bat contact, who perform animal necropsies
0, 7 days; then check every 2 years (booster if <0.5IU/mL8)
for category 3 population for risk of rabies, who are typical population?
what is the dose for prEP?
-people who interact with animals that could be rabid
-occupational or recreational activities typically involve contact with animals,
-selected travelers
-0, 7 days; then one time tier check during years 1-3 after OR
-0, 7 days; then booster dose at 21 days - 3 years
for category 4 population for risk of rabies, who are typical population?
what is the dose for prEP?
- same at risk populations as category 3, but risk less then 3 years
-0, 7 days
which travelers should be considered for PrEP for rabies?
- any occupational or recreational activities that increase their risk for exposure to potentially rabid animals (particularly dogs)?
- no access to safe postexposure prophylaxis? (rural areas, no PEP readily available)
- duration of stay / repeat travel
what are 2 types of rabies vaccines available?
Human Diploid Cell Rabies Vaccine (HDCV) - Imovax
Purified Chick Embryo Cell vaccine (PCEC) - RabAvert
compare to PCEC, HDCV has higher chance of getting this adverse reaction..
systemic hypersensitivity reacions - malaise, pruritis, urticaria - 6% of ppl receiving booster
how to do first aid if animal bite?
copious amounts of soap and water
povidone iodine
or other products with virucidal activity
-clean immediately!
-delay suturing any wounds for a few days if unvaccinated
-inject rabies immune globulin into all exposed tissues before closing the wound
if vaccinated, what is post exposure prophylaxis of rabies?
2 doses of modern cell culture vaccine ASAP - 0, 3 days
rabies immune globulin should not be administered to people who were previously vaccinated - can lead to a dimished immune response to vaccine and provides no benefit
if unvaccinated, what is post exposure prophylaxis of rabies?
rabies immune globulin
- 20 IU/kg for human RIG (HRIG)
- 40 IU/kg for equine RIG
- inject as much of the dose-appropriate volume of RIG as is anatomically feasible at wound sites
4 or 5 injections of rabies vaccine over 14 days - 0, 3, 7, 14 (and 28 if immunocompromised)
which rabies immunoglobulins are available?
human RIG
equine RIG
if access to RIG is delayed, what to do?
start the vacccine ASAP
add RIG 7 days or less after the first dose of vaccine
(after 7 days, no benefit)
can pregnant woman get PEP for rabies?
yes
rabies vaccines grown in animal brains are still in use in low- and middle- income countries. daily large-volume injection (5ml) 14-21 days. is this safe?
no because of variability in the potency - decline and travel to a location where acceptable vaccines and RIG are available.
what is rubella virus?
spherical, positive-sense, single-stranded RNA
family Matonaviridae
genus Rubivirus
how are rubella virus transmitted?
-person-to-person
-droplets shed from the respiratory secretions of infected people - shed from 7 days before the onset of the rash to 5-7 days after rash onset
-mother to fetus (highest risk for congenital rubella syndrome if infected in first trimester)
where is Rubella at risk the most?
Africa, East Asia, South Asia
what is congenital rubella syndrome?
how common is CRS globally?
-born with cataract or congenital heart disease
-mom infected during pregnancy especially before 13th week of pregnancy is at most danger
100,000 cases per year wordlwide
what are the symptoms of rubella?
-25-50% asymptomatic
-rash usually starts on the face, becoming generalized within 24 hours
-anorexia, mild conjunctivitis, low-grade fever, malaise, runny nose, sore throat can occur first before the rash appearance
-adolescents, adults, esp women - can present with transient arthritis.
-rare complications: encephalitis, thrombocytopenic purpura
how to diagnose rubella?
serologic - rubella IgM or significat increase in rubella IgG
-RT-PCR can be used to detect virus infection
-viral culture also ok but time consuming and expensive
what virus (genus, family) cause measles?
genus Morbillivirus
family Paramyxoviridae
how does measles get transmitted?
what is the contagious period?
respiratory droplets
4 days before until 4 days after rash onset
what is the incubation period for measles to onset of prodrome symptoms?
what is prodrome symptoms before rash appears?
when does the rash appear?
11-12 days from exposure;
fever, high fever (40.6), conjunctivitis, coryza (runny nose), cough, small spots with white or bluish-white centers on an erythematous base appearing on the buccal mucosa (Koplik spots)
rash appears~14 days (3-7 days after onset of prodromal symptoms)- begin on face and generalized, lasting 4-7 days; red, blotchy (maculopapular) rash
what are common measles complications?
diarrhea 8%, middle ear infection (7-9%), pneumonia (1-6%)
encephalitis - permanent brain damage - 1 per 1000-2000 cases
what is subacute sclerosing panencephalitis (SSPE)?
progressive neurologic disorder caused by measles virus that usually presents 5-10 years after recovery from the initial infection.
mental and motor deterioration, can progress to coma and death.
1/5000 cases; higher among children <5 years of age.
how to diagnose measles?
serologic test - IgM, IgG seroconversion, or a significant rise in measles IgG level
isolation of measles virus
RT-PCR testing
what is the dose of Vitamin A for measles for kids?
<6 months
6 months - 12 months
12 months and older
50,000 IU qd for 2 days
100,000 IU qd for 2 days
200,000 IU qd for 2 days
if vit A deficiency, administer an additional (a third) age-specific dose 2-4 weeks
when was the measles vaccine licensed?
1963
acceptable presumptive evidence of immunity to measles includes birth before .. which year?
1957
what is the routine vaccine schedule for MMR or MMRV?
at 12 month, and 28 days later
patient was born in 1963-1967 in US - which measles vaccine was administered then, and what should we do for these population?
formalin-inactivated measles vaccine - short-lived immunity;
need MMR live vaccine again
what is the effectiveness of MMR vaccine in measles after dose 1 at age 9 months? dose 1 at 1 year old?
effectiveness of 2 doses?
85%; 93%
97%
what are the adverse reactions from MMR vaccine?
-anaphylaxis (2-14 / million)
-febrile seizures (1/3000-4000 doses)
-thrombocytopenia (1/40,000 doses)
-joint symptoms (arthralgia ~25% of nonimmune postpubertal females from the rubella component of the MMR vaccination)
any egg allergy concern with MMR?
no, can receive MMR or MMRV vaccine without prior routine skin testing or the use of special protocols.
Is HIV patient ok to get MMR/MMRV?
yes - if not immunosupressed:
children 5 and under:
- if CD4 is equal to or greater than 15% for 6 months
children 6 and up:
-CD4 15% and up AND CD4 count 200 cells/ml or more for 6 months
after how many months of chemotherapy, can a person get MMR?
3 months
what is considered high dose steroid?
20mg or 2 mg/kg body weight of prednisone, 2 weeks or more
how long do you need to wait to get MMR if you had high dose steroid ?
1 month
how long do you have to wait to get MMR/MMRV after immunosuppressive therapies?
3 months
how long do you need to wait after getting MMR or other live vaccines to become pregnant?
28 days after live-virus vaccine
if baby has personal or family history of seizure, which one MMR or MMRV vaccine should be used?
MMR and separate varicella vaccine at the same visit
-MMRV has higher chance of fever and febrile seizures 5-12 days after the first dose among children age 12-23 months.
1 febrile seizure / 2,300-2,600 MMRV
if the baby has thrombocytopenia after first dose of MMR or MMRV within 6 weeks, do you administer 2nd dose?
NO
what is post-exposure prophylaxis of measles?
-measles-containing vaccine within 72 hours after exposure
-within 6 days, IG
after getting measles IG, when can you get vaccination of MMR or MMRV?
6 months after IG intramuscularly;
8 months after IG intravenously
which virus causes smallpox?
variola virus, genus Orthopoxvirus
among genus Orthopoxvirus, which viruses can cause human diseases?
variola virus (smallpox), cowpox virus, vaccinia virus, mpox virus
how are smallpox viruses trasnsmitted?
respiratory droplets; contact with infectious skin lesions or scabs
how does Vaccinia virus get transmitted?
-from live vaccine
-touching the fluid or crust material from the inoculation lesion of someone recently vaccinated against smallpox
-touching contaminated materials like sheets and towels
-contact with agricultural animals, often bovids, infected with sylvatic vaccinia-like viruses
how is cowpox virus transmitted?
-wild rodents are the reservoirs of cowpox virus
-mammals (cats, cows, humans) are incidental hosts
-direct contact with infected animals including incidental hosts
what is suspected reservoir for mpox virus?
small mammals - not monkeys
how is mpox transmitted?
-contact with infected wildlife or wildlife products, infected humans, or the bodily fluids or respiratory droplets from infected wildlife or people
-person-to-person: respiratory secretions and skin contact with lesion or lesions
-contact with infectious materials
-sexual contact; esp. MSM
which countries there had been reports of vaccinia-like viruses?
Brazil, Columbia - dairy workers;
India - cattle and buffalo herders
which countries did Cowpox occur?
Europe and the Caucasus (Georgia)
which country or regions are at risk of Mpox?
West and Central Africa, notably the Congo Basin - Democratic Republic of the Congo;
US - from infected pets from Africa;
Cameroon, Central African Republic, Cote d’Ivoire, Gabon, Liberia, Nigeria, Republic of the Congo, Sierra Leone, Nigeria
what are the symptoms of smallpox?
acute onset of fever, head and body aches, malaise, sometimes vomiting
-disseminated rash of firm, deep-seated vesicles or pustules in the same stage of development on each affected body site.
-lesions on the palsm or soles and a centrifugal distribution of lesions on the body
what are the symptoms of cowpox & Vaccinia?
-localized vesicular-pustular lesions
-cowpox occasionally are ulcerative
-most often self-limited
what are the symptoms of Mpox?
-febrile prodrome
-vesiculopustular rash that sometimes involves the palms and soles
-marked lymphadenopathy - distinguishing from smallpox
-from 2022: different clinical presentation- rash smaller and less diffusely spread
-most self-limited (some death)
how to diagnose orthopoxvirus infection?
PCR testing or virus isolation
how to prevent spreading orthopoxvirus infection to other parts of the body or to other people?
keep lesions covered until the scab detaches; avoid touching their eyes before proper hand washing;
how to treat ocular involvement from orthopoxvirus infections ?
topical antivirals - e.g. trifluridine drops
treatment for Mpox?
tecovirimat have been used but more evaluations needed;
tecovirimat is available as investigational new drug
how to prevent mpox and other orthopoxvirus infection?
avoid contact with sick or dead animals, including wild animals, pets, domestic ruminants (buffalo, cattle)
who can get vaccines for smallpox?
people at occupational risk - lab workers, military personnel
who should get vaccinated for mpox?
people at risk of mpox exposure and infection during travel complete mpox vaccination series at least 2 weeks prior to departure.
after exposure within 4 days - get vaccination
what is the causing agent of TBE (tick-borne encephalitis)?
Tick-borne encephalitis virus - single-stranded RNA virus
genus Flavivirus
3 main subtypes: European, Far Eastern, Siberian
what are the ticks that cause TBE virus transmission?
bite of an infected tick of the Ixodes species,
primarily I. ricinus (European subtype) or I. persulcatus (Far Eastern and Siberian subtypes)
what are preferred habitats for ticks causing TBE?
in or near the edges of forests with deciduous or coniferous trees and low-growing dense brush
what is the primary amplifying host of TBE virus?
small rodents
what are other ways of getting TBE other than through bite of tick?
-ingesting unpasteurized diary products from infected cows, goats, sheep
-direct person-to-person possible but rare
which areas are at risk of TBE?
which countries have most reported cases?
western and northern Europe through to norther and eastern Asia
-Russia, including Siberia (most reported)
-the Baltic states (Estonia, Latvia, Lithuania), Czech Republic, Slovenia - highest incidence in recent years
-Other European countries with reported cases: Austria, Belarus, Belgium, Bosnia,Bulgaria, Croatia, Denmark, Finland, France, Germany, Hungary, Italy, Liechtenstein, Moldova, Netherlands, Norway, Poland, Romania, Serbia, Slovakia, Sweden, Switzerland, Ukraine, and the United Kingdom.
-Asian countries with reported TBE cases or virus activity include China, Japan, Kazakhstan, Kyrgyzstan, Mongolia, and South Korea.
The risk for TBE virus infection for an individual traveler is greatly affected by ….
their planned itinerary and activities.
the same ticks that transmit TBE virus also can transmit other pathogens, including …?
Borrelia burgdorferi (the agent for Lyme disease),
Anaplasma phagocytophilum (anaplasmosis), and
Babesia spp. (babesiosis)
what are the symptoms of TBE?
-2/3 are asymptomatic
-incubation- 8 days (2-28 days)
-most often milder disease forms or biphasic course:
1. nonspecific febrile illness for several days then asymptomatic period
2. CNS involvement - aseptic miningitis, encephalitis, meningoencephalomyelitis (altered mental status, ataxia, cognitive dysfunction, cranial nerve palsies, limb paresis, meningeal signs, rigidity, seizures, tremors)
-severity increases with age (milder disease in children)
how to diagnose TBE?
-history of tick bite (30% do not recall a tick bite)
-febrile illness that progress to neuroinvasive disease within 4 weeks
-serology teset: IgM performed on serum or CSF –> when interpreting results, consider the patient’s vaccination history, date of symptom onset, and info about other flaviviruses
-virus isolation and RT-PCR should not be used to rule out TBE
what is the vaccine for TBE? dose?
when do you use this vaccine?
TICOVAC - inactivated, whole-virus vaccine with formulations for kids 1-15 yr and adults 16 and up.
1-15 years (0.25ml) : 0, 1-3 months, 5-12 months after dose 2
16 and up (0.5ml) : 0, 14 days-3 months, 5-12 months after dose 2
Every 3 years
-vaccine recommended if extensive tick exposure based on planned outdoor activities (camping, fishing, hiking, hunting) and itinerary; moving to endemic area
precautions of TICOVAC in pregnancy and lactating?
no studies assessed the safety
