3. Flu, Covid, TB

Which type of influenza can infect humans and mammals?

Type A

How is influenza transmitted? Precautions?

Droplet nuclei; droplet precaution until asymptomatic for 24h

Which type of influenza are more severe?

Type A and B

Onset of influenza (incubation/onset)

Incubation: 1-4 days

Rapid symptom onset: 1-7 days

S/S of influenza

Fever, cough, cervical LN enlargement (esp during flu season)

S/S of influenza in elderly

Extreme fatigue, confusion (potentially lacks typical flu symptoms)

Diagnostic testing for influenza

Nasohpharyngeal brushing w/ rapid antigen DFA (PCR more accurate though)

Diagnostic testing/findings for influenza with suspected viral pneumonia

CXR with diffuse/hazy infiltrate and sputum for viral PCR

Ddx for acute presentation of influenza

- Acute HIV

- Tick-born illnesses

Reye syndrome

- Severe complication of influenza and other viral diseases in young children → rapid progression to liver failure and encephalopathy

- Associated with ASA use for viral infections

MC viral infections that cause Reye syndrome

Influenza and varicella

Treatment of influenza in children w/ fever

Acetaminophen and/or ibuprofen

CDC recommendation for antiviral therapy for influenza

Oseltamivir (tamiflu)

Indications for antiviral therapy for influenza

Shortens duration, decreases risk of complications

Most effective measure for preventing the flu

Annual vaccination

Contraindications for influenza vaccine

- Severe egg allergy

- Hx of Guillain-Barre

- Active acute illness

Post-exposure prophylaxis for influenza

Oseltamivir (tamiflu)

When is viral load highest for COVID?

Day 4 of symptoms (due to population immunity)

How is COVID transmitted?

Respiratory droplets (and aerosol during respiratory procedure)

Average incubation period of COVID

5 days

Children & COVID

High rates of infection BUT lower symptom rates

MC presentation of COVID

Asymptomatic (33%)

Diagnostic testing for COVID

PCR: best for early infection detection

Diagnostic labs/findings with severe COVID

Elevated coagulopathic signs (increased risk of clotting)

MC symptoms of long COVID

Fatigue, loss of smell/taste, dyspnea

Risk factors for long COVID

Upper-middle age male

Indications for antivirals for COVID

Immunosuppression (paxlovid or remdesivir)

All hospitalized patients require ______ for prophylaxis of ______

heparin; DVT

Treatment for COVID w/ hospitalization and supplemental O2

Remdesivir, dexamethasone +/- immunomodulators

Areas endemic to TB

Asia, Africa, Latin America

How is TB transmitted? Precautions?

- Airborne droplet nuclei

- Private with negative air-flow until 3 consecutive AFB smears

Pathophysiology of TB

M. tuberculosis is inhaled → alveoli, ingested by alveolar macrophages & escape → infection

Latent TB

- Inactive TB

- Organisms dormant within granulomas

- NOT transmissible

What are most TB infections from? When?

Activation of LTBI within 2 years of primary infection

Risk factors for activation of LTBI

Gastrectomy, silicosis, DM

S/S of pulmonary TB

Fever, night sweats, anorexia, chronic cough (dry → productive), hemoptysis with advanced disease

PE findings with pulmonary TB

Post-tussive apical rales

Post-tussive apical rales on exam is associated with...

Pulmonary TB

Diagnostic workup & findings of TB

CXR: Cavitary lesions of apical lobe

Diagnostic workup/findings of TB & HIV

- Lower lung/diffuse/miliary infiltrates

- Lymphadenopathy (hilar/mediastinum)

How to test for pulmonary TB?

- Sputum sample on NAAT (1 day), culture (6-8 weeks)

- 3 samples at least 8 hours apart, 1 as morning specimen & LM exam of sputum for AFB

What is done in addition to culture analysis of sputum for TB?

Always test for drug susceptibility (Rifampin and INH)

Testing for LTBI (asymptomatic) + FYI

PPD - TB skin test

- Assess induration in 48-72 hrs

- Does NOT distinguish active vs. latent

Induration & risk factors

High risk → 5mm

Increased risk → 10mm (residents/employees of high-risk settings — ex: hospitals)

What diagnostic test is indicated with a prior BCG vaccine?

Quantiferon Gold

Basic principles of treatment of TB

Multiple medications w/ strict adherence

When is directly observed therapy (DOT) indicated for treatment of TB?

ALL patients with drug-resistant TB

General treatment of active, drug-susceptible TB

4, 6, 9 month treatments (as short as possible)

4 month regimen for drug-susceptible TB

4 drug therapy → 3 drugs

6 month regimen for drug-susceptible TB

4 drug therapy → decrease throughout treatment duration with confirmed sensitivities

Outpatient therapy vs. DOT

DOT - Increase doses and intervals

Which medication is contraindicated by pregnancy for treatment of TB?

Pyrazinamide

Testing for close contacts of TB infection

PPD or Q-gold, repeat in 10-12 weeks

2 main drugs for treatment of latent TB

INH + rifampin

What should be administered with INH to prevent peripheral neuropathy?

Pyridoxine (vitamin B6)

Side effects of isoniazid (INH)

Peripheral neuropathy, hepatitis, rash, mild CNS

What to monitor with isoniazid (INH)

LFTs and neuro exams

Drug interaction with isoniazid (INH)

Phenytoin → disulfiram rxn

Side effects of rifampin

Hepatitis, orange urine/secretions, fever, rash, bleeding issues, renal failure

What to monitor with rifampin

CBC and LFTs

Side effects of pyrazinamide

Elevated uric acid, hepatitis, joint aches, rash, GI,

What to monitor with pyrazinamide

Uric acid and LFTs

Side effects of ethambutol

Optic neuritis, rash

+ caution with kidney disease

**Avoid if opthalm observation not feasible

What to monitor with ethambutol

Visual acuity and R/G color discrimination

Side effects of rifapentine

Bone marrow suppression, hepatitis, orange urine/secretions, hematuria/pyuria, hepatitis, GI, flu

What to monitor with rifapentine

CBC and LFTs

Contraindications of moxifloxacin

QT prolongation, strenuous activity (tendon rupture)

Drug-resistant TB

Resistant to one first line drug (INH and rifampin)

MDR-TB

Resistant to both first line drugs +/- others

MCC of treatment failure of TB

Non-adherance to therapy