Viruses Flashcards

Question

HIV

Answer 1

Human immunodeficiency virus (HIV) is a blood-borne, sexually transmissible virus Typically transmitted via Sexual intercourse Shared intravenous drug paraphernalia Mother-to-child transmission (MTCT), which can occur during the birth process or during breastfeeding

Answer 2

HIV-1 probably originated from one or more cross-species transfers from chimpanzees in central Africa HIV-2 is closely related to viruses that infect sooty mangabeys in western Africa

Answer 3

Unprotected sexual intercourse, especially receptive anal intercourse (8-fold higher risk of transmission) Large number of sexual partners Prior or current STDs Gonorrhea and chlamydia infections increase the HIV transmission risk 3-fold Syphilis raises the transmission risk 7-fold Herpes genitalis raises the transmission risk up to 25-fold during an outbreak Sharing of intravenous drug paraphernalia Receipt of blood products (before 1985 in the US) Mucosal contact with infected blood or needle-stick injuries Maternal HIV infection

Answer 4

Acute seroconversion manifests as a flulike illness, consisting of fever, malaise, and a generalized rash Asymptomatic phase is generally benign (aka asymptomatic) Generalized lymphadenopathy is common ; may be a presenting symptom Weight loss

Answer 5

high-sensitivity enzyme-linked immunoabsorbent assay (ELISA) should be used for screening CD4 T-cell count is a reliable indicator of the current risk of acquiring opportunistic infections

Answer 6

Cytomegalovirus (CMV) testing Syphilis testing Rapid amplification testing for gonococcal and chlamydial infection Hepatitis A, B, and C serology Anti-Toxoplasma antibody Ophthalmologic examination A purified protein derivative skin test (PPD) to evaluate for tuberculosis infection Chest radiography should be performed in patients with a positive PPD test result

Answer 7

Category A - asymptomatic HIV infection without a history of symptoms or AIDS-defining conditions Category B - HIV infection with symptoms that are directly attributable to HIV infection Category C - HIV infection with AIDS-defining opportunistic infections (previous slide with opportunistic infections 3 categories are further subdivided based on the CD4+ T-cell count Categories A1, B1, and C1 - CD4+ T-cell counts > 500/µL Categories A2, B2, and C2 - CD4+ T-cell counts 200/µL - 400/µL A3, B3 and C3 - CD4+ T-cell counts < 200/µL

Answer 8

Efavirenz/tenofovir/emtricitabine (EFV/TDF/FTC) Ritonavir-boosted atazanavir + tenofovir/emtricitabine (ATV/r + TDF/FTC) Ritonavir-boosted darunavir + tenofovir/emtricitabine (DRV/r + TDF/FTC) Raltegravir + tenofovir/emtricitabine

Answer 9

``` Virologic efficacy Toxicity Pill burden Dosing frequency Drug-drug interaction potential Drug resistance testing results Comorbid conditions ```

Answer 10

Untreated HIV infection - overall mortality rate > 90% Average time from infection to death is 8-10 years, although individual variability ranges from less than 1 year to long-term nonprogression Variables implicated in HIV's rate of progression, including CCR5-delta32 heterozygosity, mental health, concomitant drug or alcohol abuse, superinfection with another HIV strain, nutrition, age; also primary risk factor for initial infection

Answer 11

Sexual transmission Prevention measures include the following: Abstinence when possible Reduction in number of sexual partners Using barrier contraception Treatment of concurrent sexually transmitted diseases (STDs) Testing of self and partner for HIV infection and other STDs Vertical transmission Prevention measures include the following: Maternal testing Effective control of maternal infection Prenatal antiviral therapy and treatment of mother and infant during labor, delivery, and the neonatal period Cesarean delivery Avoidance of breastfeeding (unless local conditions make this unsafe or unfeasible) Postexposure prophylaxis

Answer 12

``` Human papillomavirus (HPV) produces epithelial tumors of the skin and mucous membranes More than 100 HPV types are known HPV types 6 and 11 - low risk oncogenic potential; formation of condylomata and low-grade precancerous lesions HPV types 16 and 18 - high-risk types of HPV; responsible for most high-grade intraepithelial lesions that may progress to carcinomas ```

Answer 13

Anogenital HPV is the most common sexually transmitted infection in the US Condylomata acuminata are clinically apparent in 1% of the sexually active population (molecular studies - 10-20% of men/women aged 15-49 yo HPV exposed) Prevalence of 4-13% has been reported by sexually transmitted disease (STD) clinics Common among adolescents and young adults Estimated 80% of sexually active women will have been infected by age 50

Answer 14

An incubation period (latency period) is 3 months, but periods as long as 20 months Age of onset usually 2-4 yo, but as late as juvenile onset documented, younger age worse prognosis Symptoms include hoarseness, voice changes, croupy cough, stridor Diagnosis by direct laryngoscopy Prevention by HPV vaccine Treatment by direct surgical resection (recurrences are the rule), tracheostomy occasionally required

Answer 15

Most diagnoses are made clinically Exam of genital lesions with acetic acid helpful Colposcopy & biopsy to determine extent of intraepithelial neoplasia PAP Smear

Answer 16

No single curative treatment for condylomata acuminata Treatment of most HPV infections involves agents that directly ablate the lesions Medications used in treating HPV disease: Immune response modifiers – imiquimod and interferon alfa and are primarily used in treatment of external anogenital warts or condylomata acuminata Cytotoxic agents - antiproliferative drugs podofilox, podophyllin,

Answer 17

Highly contagious airborne disease that causes an acute febrile illness (ranging from mild to respiratory failure/death) Most significant immunologic surface proteins include hemagglutinin (H) and neuraminidase (N), which determine virulence

Answer 18

Abrupt onset of illness is common (may be able to report the time when the illness began) Fever may vary widely, 100-104°F; feeling feverish /chills Sore throat may be severe and may last 3-5 days (often reason for office visit) Frontal/retro-orbital headache is common; usually severe. (ocular symptoms photophobia, burning sensations, and/or pain upon motion Ptosis is common

Answer 19

Pneumonia in highest risk groups: women in the third trimester of pregnancy, elderly individuals, especially nursing home patients; those with cardiovascular disease usually constitute the highest risk group Secondary bacterial pneumonia Staphylococus aureus (most severe with cavitary infiltrates) Haemophilus pneumonia Steptococcus pneumoniae (S pneumoniae and H flu ususally develop Methicillin-susceptible S aureus (MSSA) and methicillin-resistant S aureus (MRSA) pneumonias, often severe & difficult to treat, fatal within 24 hours occasionally

Answer 20

Viral culture of nasopharyngeal samples and/or throat samples Rapid diagnostic tests are available, but because of cost, availability, and sensitivity issues, most flu is diagnosed clinically PCR Serologic Testing

Answer 21

4 prescription antiviral drugs: oseltamivir, zanamivir, amantadine, rimantadine

Answer 22

one of the most contagious infectious diseases, at least a 90% secondary infection rate in susceptible domestic contacts Measles is marked by prodromal fever, (3-Cs) cough, coryza, conjunctivitis Transmitted via respiratory droplets, which can remain active and contagious, either airborne or on surfaces, for up to 2 hours

Answer 23

``` Morbidity and mortality increased Immune deficiency disorders Malnutrition Vitamin A deficiency Inadequate vaccination (60-fold increase in risk of disease due to exposure to imported measles cases) ```

Answer 24

Incubation period 10-12 days 1st sign usually a high fever often >104 lasting 4-7 days Prodromal phase associated with malaise, fever, anorexia, classic triad (the ‘3-Cs’): Conjunctivitis Cough (may be the final symptom to appear though) Coryza

Answer 25

otitis media, interstitial pneumonitis, bronchopneumonia, laryngotracheobronchitis (ie, croup), exacerbation of tuberculosis acute encephalitis

Answer 26

Serologic testing for IgG (4 fold increase acute-convalescent serum) and IgM (positive by 3rd day of rash for 30-60 days) Isolation of the virus Reverse-transcriptase polymerase chain reaction (RT-PCR) CBC may reveal leukopenia with a relative lymphocytosis and thrombocytopenia LFTs results may reveal elevated transaminase levels in patients with measles hepatitis CXR if pneumonia suspected

Answer 27

Supportive, IV hydration Vitamin A – reduces severity & duration 50% Postexposure prophylaxis should be considered in unvaccinated contacts Antibiotic treatment of 2nd infections, e.g. pneumonia & otitis media Ribavirin (IV or aerosolized) - treat severely affected and immunocompromised adults with SSPE, no controlled studies MMR - preventive if administered within 3 days of exposure, contraindicated in HIV with CD4 count < 15% Human Ig within 6 days of exposure

Answer 28

MC virus causes a benign viral infection almost exclusively limited to humans Papules are umbilicated and contain a caseous plug

Answer 29

Children - most common, become infected through direct skin-to-skin contact or indirect skin contact with fomites, e.g. bath towels, sponges, and gymnasium equipment Immunocompetent adults - sexually transmitted disease (STD); few lesions limited to the perineum, genitalia, lower abdomen, or buttocks Immunocompromised children or adults - widespread, persistent, and atypical molluscum contagiosum in those with AIDS with low CD4 counts

Answer 30

Orthopoxvirus - resembles variola (smallpox) and vaccinia Parapoxvirus - orf and milker’s nodule viruses Unclassified (with features that are intermediate between those of the orthopox and parapox groups)

Answer 31

Face, trunk, and extremities is observed in children; relatively common in the groin, perineal or genital (not pathognomonic of abuse) Groin and genitalia in adults Lesions are seldom found on the palms, soles, oral mucosa, or conjunctiva

Answer 32

Spontaneous resolution generally occurs by 18 months in immunocompetent individuals; may persist up to 5 years Treatment options: Benign neglect - primum non nocere (first do no harm) Direct trauma to lesions: acids, cryotherapy, pulse laser Antiviral therapy Immune response stimulation

Answer 33

``` Mumps is an acute, self-limited, systemic viral illness characterized by the swelling of one or more of the salivary glands, typically the parotid glands RNA virus Salivary glands (also pancreas, testes) show edema and desquamation of necrotic epithelial cells lining the ducts ```

Answer 34

Overall prognosis in uncomplicated mumps is excellent Encephalitis: Rates of mumps encephalitis 5:1000 reported mumps cases Sensorineural deafness Orchitis (usually unilateral) Oophoritis Pancreatitis

Answer 35

Supportive care Reduce acidic foods, both salivary gland & gastric issues Ice packs to parotid gland; ice/scrotal support for orchitis Analgesic/antipyretics Isolation for 5 days Vaccine coverage

Answer 36

viral disease that affects the CNS, single stranded RNA | Transmitted in saliva or in aerosolized secretions from infected animals, typically via a bite

Answer 37

Incubation period Asymptomatic; average duration is 20-90 days, usually < 1 year; but up to 7-19 years. Incubation period < 50 days more likely if the patient is bitten on the head or neck or if a heavy inoculum is transferred through multiple bites, deep wounds, or large wounds Rabies virus is segregated from the immune system ; no antibody response Prodromal period Virus enters the CNS; duration 2-10 days Paresthesia, pain, intense itching at inoculation site is pathognomonic for rabies, may be only presenting sign; occurs in 50% Acute neurologic period Duration 2-7 days Objective signs of developing CNS disease: muscle fasciculations, priapism, and focal or generalized convulsions Patients may die immediately or may progress to paralysis, 1st in bitten limb at first but usually becomes diffuse Furious rabies: Agitation, hyperactivity, restlessness, thrashing, biting, confusion, or hallucinations lasting < 5 minutes; becomes episodic and interspersed with calm, cooperative, lucid periods Episodes may be triggered by visual, auditory, or tactile stimuli or spontaneous; seizures may occur Hydrophobia/aerophobia present in 50%; larynogospasm / diaphragmatic spasms with drinking water or air blown in face May end in cardiorespiratory arrest or may progress to paralysis Paralytic rabies (dumb rabies or apathetic rabies) Relatively quiet; 20 % do not develop the furious form Paralysis occurs from the outset Coma

Answer 38

Rabies vaccine IM (deltoid) - 1 mL on days on days 0, 3, 7, and 14 (if immunocompromised, add an additional dose: 1 mL IM deltoid on days 0, 3, 7, 14, and 28) Rabies immunoglobulin - 20 IU/kg infiltrated as much as feasible around and under the bite wound; if any left over, give IM (gluteus) HRIG may be administered as long as 7 days after the first dose of vaccine (if not immediately available ) Prophylaxis may be discontinued if the animal does not develop rabies within 10 days or is found to be free of rabies upon sacrifice Pregnancy is not a contraindication to postexposure prophylaxis against rabies

Answer 39

human herpesvirus 6 (HHV-6) Replication of the virus occurs in the leukocytes and the salivary glands Classic presentation of roseola infantum is 9-12 mo infant with acute onset high fever; commonly a febrile seizure; 72 hours later rapid defervescence with onset morbilliform rash (early invasion of the CNS may occur) HHV-6 then remains latent (like other herpes viruses) in most patients who are immunocompetent

Answer 40

Acute onset of fever Febrile seizure in 15% Lack of URI or GI symptoms, playful despite fevers of 104-105 After acute defervescence, exanthem: generalized but subtle with either discrete, small, pale pink papules or blanchable, maculopapular

Answer 41

Young children - mild constitutional symptoms, rash, and suboccipital adenopathy Older children, adolescents, and adults, rubella may be complicated by arthralgia, arthritis, and thrombocytopenic purpura Rare cases occur of rubella encephalitis Pregnant women

Answer 42

``` Incubation is usually 14-21 days after exposure to a person with rubella Conjunctivitis Sore throat Headache General body aches Low-grade fever Chills Anorexia Nausea Forchheimer sign ```

Answer 43

classic triad of congenital rubella syndrome consists of: Sensorineural hearing loss Congenital heart disease Ocular abnormalities including cataract, infantile glaucoma, and pigmentary retinopathy

Answer 44

Congenital rubella syndrome should be strongly suspected in infants > 3 mo if rubella-specific IgG antibody levels are observed and do not decline at the rate expected from passive transfer of maternal antibody (i.e. equivalent of a 2-fold decline in HI titer per mo) Rubella-specific immunoglobulin M (IgM) antibody in a single serum sample Rubella-specific IgG rise

Answer 45

Inhalation of contaminated respiratory droplets, the virus infects the conjunctivae or the mucosae of the upper respiratory tract Viral proliferation occurs in regional lymph nodes of the upper respiratory tract 2-4 days after initial infection

Answer 46

Incubation period of 10-21 days Not heralded by a prodrome Begins with the onset of an exanthem, infectious 1-2 days prior to rash developing Small, erythematous macules appear on the scalp to face to trunk to limbs Rapid sequential progression over 12-14 hours to papules to clear vesicles to pustules, which umbilicate and crust Intense pruritus typical with vesicles Remains infectious for 4-5 days after the rash develops, as last vesicle crusts over

Answer 47

Secondary bacterial infection 2nd bacterial infection of skin lesions most common complication - impetigo, cellulitis, and erysipelas Staphylococci & streptococci most common bacteria Disseminated primary varicella infection Disseminated primary varicella infection seen in immunocompromised or adult populations, ``` CNS complications Reye syndrome – associated with ASA Guillain-Barré syndrome – ascending paralysis Acute cerebellar ataxia (post-varicella) Encephalitis ``` Hemorrhagic complications

Answer 48

Tzanck smear of vesicular fluid - multinucleated giant cells and epithelial cells with eosinophilic intranuclear inclusion bodies Vesicular fluid culture – 40% sensitivity, better with direct immunofluorescence & PCR Serologic testing – multiple tests for IgG Chest radiography – signs of pneumonia Histologic examination – nonspecific with herpes

Answer 49

Clip nails Antihistamines Topical & parenteral antibiotics if 2nd infections Acyclovir if risk for severe disease