Viral and Mosquito Borne Flashcards
Influenza
-the flu
-causative: influenza A and B virus
-reservoir- humans
-incubation- 1-4 days, average 2
-worldwide
-most common in temperature climates during winter
-spreads via respiratory droplets
-causes periodic epidemic, has potential to cause global pandemics
-pandemic occurs when new strain emerges for which humans have had little to no previous exposure
-acute, febrile viral respiratory tract infection
-3 types (A-C) based on core protein -> only A and B cause significant disease
-type A are further classified based on 2 specific antigens, hemagglutinin (HA or H) and neuraminidase (NA or N), found on the surface of the virus
-antigens are responsible for HN classification often seen on annual vaccines
-constantly undergo genetic changes via antigenic drift (frequent and minor) and antigenic shift (infrequent and significant), new and updated vaccinations are required each year
Influenza clinical diagnosis
-acute fever, chills, rigors, malaise, myalgia, headache, rhinorrhea, nonproductive cough
-nausea, vomiting, diarrhea may occur in some pts -> mostly children
-immunocompromised, extremes of age, pregnant women, residents of long term care facilities, and those with preexisting medical conditions are more likely to have severe disease and complications
-pneumonia (from influenza directly or secondarily from bacteria) is a potential complication
influenza treatment
-rapid influenza dx test (RIDT) are immunoassays that detect influenza A and B viral antigens
-nasopharyngeal swabs tested for using polymerase chain reaction (PCR)
-2 classes of drugs to treat: adamantanes include amantadine and rimantadine -> target and inhibit function of the M2 protein and are only effective against influenza A
-increased resistance to these drugs over years and efficacy against both influenza A and B -> neuraminidase inhibitors are preferred for treatment and prophylaxis
-neuraminidase inhibitors include oseltamivir, zanamivir, and peramivir
-oseltamivir is taken orally and zanamivir is inhaled powder
-newer drug -> peramivir -> indicated for treatment only (not prophylaxis) and is given as single intravenous dose
-medications are thought to decrease duration and severity of illness and are only effective when initiated within 48 hours of symptoms onset
rubeola
-causative agent- Measles virus (MV)
-incubation- 7-21 days, average 10-14 days
-worldwide
-highly contagious
-vaccine preventable
-high fever, cough, coryza, conjunctivitis followed by maculopapular rash
rubeola signs and symptoms
-following 7-21 day incubation:
-prodromal symptoms- high fever, malaise, conjunctivitis, coryza (runny nose), and cough
-koplik spots: small white to gray spots on the buccal mucosa opposite the lower molars (grains of salt on a red background)
-pathognomonic and may appear 2-3 days before viral exanthem
-after 3-4 days (range (1-7 days) of prodromal symptoms -> pts enter the EXANTHEM phase of the disease, characterized by the development of a red, maculopapular rash that starts at the head and proceeds in cephalocaudal and outward progression
-rash persists for up to 7 days and fades in same order it appeared
-as rash resolves, pt enter RECOVERY phase and may continue to have mild cough for 1-2 weeks
-complications of measles- diarrhea, otitis media, pneumonia, encephalitis, seizures, and death
-infection confirms lifelong immunity
rubeola dx and treatment
-serum IgM and IgG levels can be checked
-IgM is elevated in acute phase and remain elevated for 1-2 months
-PCR can be used to detect the MV in serum, urine, oropharyngeal and nasopharyngeal secretions
-treatment is supportive
-preventable by vaccine
-koplikl spots are temporary viral enanthem and are pathognomonic for measles
-fever is high grade and tends to last for 4 days and occurs concurrently with conjunctivitis, coryza, and cough
-subacute sclerosing panencephalitis is rare and fatal degenerative disease of CNS that occurs in some pts 7-10 years about initial infection
Mumps
-aka epidemic parotitis
-causative agent- mumps virus
-incubation- 12-25 days, average 16-18 days
-worldwide
-peak incidence- late winter-early spring, sporadic outbreaks
-vaccine preventable
-known to cause parotitis
-reproduces in upper respiratory tract
-spreads via saliva, oropharyngeal secretions, and respiratory droplets
-contagious and should be isolated with droplet precautions for at least 5 days after onset of parotitis
mumps signs and symptoms
-after 12-25 day incubation:
-prodromal symptoms including low grade fever, headache, malaise, fatigue, myalgia, followed by parotitis
-parotid swelling often bilateral (75%) and progressed over next 72 hours
-glands remain swollen for about 1 week
-complications: orchitis, oophoritis (ovarian inflammation), infertility, pancreatitis, meningitis, and/or deafness
mumps dx and treatment
-most cases are self limiting
-dx is based on hx and clinical presentation
-serology can reveal acute rise of IgM or fourfold rise of IgG in convalescence phase
-IgG of no value is previously vaccinated pts
-serum and buccal/oral swabs can be tested for mumps using PCR
-treatment is mostly supportive
-vaccination is best way to prevent
rubella
-aka german measles, 3 day measles
-causative agent- rubella virus
-incubation- 12-23 days, average 14 days
-worldwide
-contagious
-vaccine preventable
-low grade fever, lymphadenopathy
-mild 3 day maculopapular rash
rubella signs and symptoms
-many cases are asymptomatic
-children exhibit milder disease than adult
-following 12-23 incubation: pts develop low grade fever, lymphadenopathy, and mild maculopapular rash that proceeds in cephalocaudal and outward progression
-lymphadenopathy tends to affect posterior auricular, suboccipital, and posterior lymph nodes
-fever and lymphadenopathy may precede the rash by a few days or occur concurrently
-rash is fainter than in measles and last about 3 days, hence the term 3 days measles
-headache, malaise, conjunctivitis, coryza, and cough may occur as part of prodrome, more commonly in older pts
-up to 70% of adolescents and adult females develop arthralgia and arthritis that may persist for several months
-complications are more common in older pts and may include thrombocytopenic purpura and encephalitis
-rubella during pregnancy- specifically first trimester -> can cause stillbirth or birth defects
-congenital rubella syndrome causes cataracts, heart defects, and deafness
rubella dx and treatment
-serum IgM and IgG levels can be obtained
-IgM will be elevated in acute phase of illness, and fourfold rise in IgG in convalescence will confirm recent infection
-PCR testing can be performed on oropharyngeal or nasopharyngeal swabs and urine
-obtaining samples from both sources will increase the likelihood of detecting the virus
-treatment is supportive and is prevented by vaccine
rubella vs measles
-similar but have some distinct differences
-rubella is characterized by low grade fever, lymphadenopathy, and rash
-measles is characterized by high grade fever, cough, coryza, conjunctivitis and rash
-rash in rubella is fainter (pink vs red) and lasts for shorter duration (3 days vs 7 days)
-rubella is milder disease but can cause congenital defects in pregnancy
-forchheimer spots are transient erythematous petechiae seen as enanthem on hard palate in about 20% of pts with rubella
-since these spots can also be seen in measles and scarlet fever -> they are not pathognomonic for rubella
-Koplik spots- small white to gray spots on buccal surface opposite the lower molars, are pathognomonic enanthem for measles
Rabies
-aka hydrophobia
-causative agent- rabies virus
-reservoirs- bats, racoons, skunks, foxes in US, dogs in developing nations
-incubation- 1-3 months mostly, onset can be delayed for years
-worldwide- highest incidence in Asia and Africa
Rabies signs and symptoms
-prodromal symptoms- fever, headache, malaise, nausea, vomiting, and pain or paresthesia at the site of bite
-when virus spreads to CNS -> pts will exhibit 1 of 2 clinical presentations of the disease
-furious rabies- most common presentation (70%) and includes classic findings of hydrophobia, insomnia, confusion, paranoia, anxiety, agitation, and hallucinations progressing to coma and death
-paralytic rabies- presents in 30% of pts and is associated with an ascending flaccid paralysis, fever, confusion, coma, and death