Viruses Flashcards
3 types of influenza viruses
A: Major cause of outbreaks (pandemic, epidemic)
B: major cause of outbreaks but not as often (epidemic)
C: Mild RTI with no outbreaks
transmission and incubation period of influenza
respiratory droplets
1 to 4 days
clinical features of influenza
- Abrupt onset of fever, myalgia, malaise, headache
- Sore throat, dry cough, sneezing, rhinorrhea
diagnosis of influenza
- Immunofluorescence antigen in respiratory epithelial cells
- RT-PCR
- Point of Care Test (Lateral Flow)
complications of influenza
- Pneumonia
- Myocarditis
- Myositis
- Reyes Syndrome
antiviral for influenza
Oseltamivir (Tamiflu) → Neuraminidase inhibitors
how do novel genetic variants for influenza arise and lead to pandemics or epidemics
different genetic variants arise by either antigenic shift or antigenic drift.
- Antigenic shift: recombination of RNA segments of two antigenic types from different animal virus strains infecting the same cell -> pandemics
- Antigenic drift: spontaneous mutations leading to minor changes in hemagglutinin -> epidemics
transmission of HIV
Direct body fluid exchange
- Sexual transmission (MSM)
- Blood Transmission (needles)
4 stages of HIV infection
- Incubation → Asymptomatic
- Acute Seroconversion Phase: Acute signs appear within 2-3 wks, resolve 2 weeks later
- Very transmissible
- CD4+ count is normal
- Asymptomatic (Latent) Phase : 7-11 years
- Viraemia is very low/almost zero but cannot be eradicated by immune system
- Serology:
- Anti-p24 IgG: high & can be used for lab diagnosis but decrease in stage 4
- Anti-p41 IgG: stays high from onset of latent phase & thru full blown AIDS
- CD4+ count: decrease progressively
- AIDS: death ~1-2 years
- increased severity of opportunistic infection → death
clinical features of HIV
- Acute Phase : Fever, Sore Throat, Lethargy, Generalised Lymphadenopathy, rash on arms/legs & trunk
- Latent Phase: Fever & fatigue, weight loss, lymphadenopathy
- AIDS:
- Malignancies: Kaposi’s Sarcoma, Cerebral or non-Hodgkin’s Lymphoma
- Skin Lesions: (can occur at all stages of HIV infx): Psoriasis, cauliflower shaped cutaneous warts, scabies
diagnosis of HIV
Diagnosis: NEEDS LAB CONFIRMATION
- ELISA
- Highly Sensitive, not as specific (could have false)
- used to detect anti-p24 antibody
- Western Blot (if ELISA is +ve)
- used to detect anti-gp41, anti-p24, anti-gp120 antibodies
- RT-PCR/PCR
- Detect Viral Load
treatment of HIV (antivirals)
- Nucleoside Reverse Transcriptase Inhibitors (NRTIs) — Zidovudine, lamivudine
- Non-nucleotide reverse Transcriptase Inhibitors (nNRTIs) — Efavirenz, Nevirapine
dengue mode of transmission
Vector Aedes Aegypti
dengue incubation period
incubation 3-10 days (infection period is 5 days from onset of fever)
dengue fever clinical features
- 85% are asymptomatic, rest appear w influenza like symptoms
- Abrupt onset of high fever lasting 2-7 days
- Severe headache w retro-orbital pain
- Muscle & joint pain
- Generalized rash w some petechiae
