Untitled Quiz

Viral & Fungal Pneumonia

• Viral pneumonia and fungal pneumonia are respiratory infections.

Viral Infection of Lower Respiratory Tract (LRT)

• Pneumonia: An infection of the lungs.
• Bronchiolitis: An infection of the small bronchioles in the lungs.

Bronchiolitis

• Acute viral infection affecting small bronchioles
• Primarily in infants and young children (under 2 years old)
• Only humans can transmit the infection
• Etiology: Respiratory Syncytial Virus (RSV)
• Incubation period: 4-8 days
• Symptoms: cough, wheezing, shortness of breath; difficulty feeding in some children.
• Signs: crackles or wheezes heard on lung auscultation
• Chest X-ray shows typical bilateral perihilar fullness of bronchioles
• Treatment: Bronchodilators, Antibiotics (to prevent secondary bacterial infections), hospitalization may be necessary for children with underlying heart or lung conditions.

Viral Pneumonia

• Viruses are a significant cause of community acquired pneumonia (CAP).
• It is a serious illness, especially in older and immunocompromised individuals.
• Viruses cause up to 35% of CAP in adults and children.
• Risk factors: Elderly, chronic chest diseases (e.g., Asthma), immunocompromised patients
• Symptoms tend to be of gradual onset and are less severe than bacterial pneumonia.
• Symptoms of viral pneumonia begin a few days after upper respiratory symptoms, such as a sore throat.
• Secondary bacterial infections are common among high-risk individuals.
• Common viral causes: Influenza virus, RSV, Coronaviruses, Para-influenza virus, Adenovirus type 7, Epstein-Barr Virus (EBV), Cytomegalovirus (CMV), Herpes simplex virus (HSV), Measles virus

Influenza Virus

• Family: Orthomyxoviridae
• Spherical or filamentous viruses
• Single-stranded, segmented RNA genome
• Three serotypes (types A, B, and C) differentiated by internal and matrix proteins
• Hemagglutinin (HA) and neuraminidase (NA) are surface glycoproteins on the virus envelope.
• Antigenic drift: minor changes in HA or NA proteins resulting in epidemics.
• Antigenic shift: major changes in HA or NA proteins resulting in pandemics due to gene reassortment.

Viral Pneumonia: Clinical features

• Incubation period: 3-4 days
• Symptoms: fever, myalgia, sore throat, nonproductive cough, headache
• Complications: pulmonary (secondary bacterial infection), non-pulmonary (myositis, encephalitis, peripheral nervous system complications like Guillain-Barré syndrome, Reye's syndrome).

Viral Pneumonia: Lab diagnosis

• Demonstration of virus antigen (RT-PCR, immunofluorescence).
• Isolation of the virus (monkey kidney cells).
• Serology (hemagglutination inhibition, complement fixation test, ELISA).

Viral Pneumonia: Treatment

• Antivirals (Amantadine, Rimantidine, Oseltamivir, zanamivir)

Viral Pneumonia: Prophylaxis

• Inactivated vaccines, inactivated subunit vaccines, recombinant vaccines, live attenuated vaccines

Coronaviruses

• Large family of viruses causing illness in humans and animals.
• Coronaviruses belong to the family Coronaviridae.
• Crown-like spikes on the outer surface.
• Enveloped, positive-sense, single-stranded RNA viruses with a helical nucleocapsid.
• Common cause of the common cold.
• Incubation period: 2-14 days
• Mortality: 11% especially for elderly individuals.
• SARS-CoV, MERS-CoV, SARS-CoV-2 (COVID-19) are important strains.

Severe Acute Respiratory Syndrome (SARS)

• Caused by a coronavirus.
• First outbreak in southern China in 2002.
• Pandemic in 2003 affecting 30 countries with over 800 deaths.
• Flu-like symptoms (fever, chills, dry cough, shortness of breath, muscle aches, diarrhea).
• Complication: pneumonia, respiratory failure, heart and liver failure.

SARS Lab diagnosis

• PCR (sputum, blood, stool), detection of serum antibodies.

SARS Treatment

• Respiratory support, ribavirin, interferons, high-dose steroids (controversial) - no vaccine.

Middle East Respiratory Syndrome Coronavirus (MERS-CoV)

• First cases in Jordan and Saudi Arabia in 2012
• People with comorbidities (diabetes, cancer, weakened immune systems, chronic lung, heart, or kidney disease) are more likely to be infected or experience severe disease
• Primarily transmitted through close contact with ill individuals.
• Incubation period: 5-6 days, range of 2-14 days.
• Symptoms: fever, cough, shortness of breath, gastrointestinal symptoms (diarrhea, nausea, vomiting).
• Complications: pneumonia, kidney failure.

MERS-CoV Lab diagnosis

• Respiratory specimens, serum.
• Serologic testing, antibody detection, real-time RT-PCR testing

MERS-CoV Treatment

• No vaccine. No specific antiviral treatment. Supportive management is crucial.

SARS-CoV-2 (COVID-19)

• Infectious disease caused by a coronavirus closely related to SARS-CoV.
• Primarily spread through respiratory droplets from infected individuals.
• ACE-2 is a functional receptor for SARS-CoV-2 and is highly expressed in pulmonary epithelial cells.
• Incubation period: 2-14 days.
• Symptoms: fever, cough, shortness of breath; diarrhea or upper respiratory symptoms are less frequent
• Potential complications: pneumonia, multi-organ failure.

COVID-19 Diagnosis

• Molecular tests (RT-PCR), Serology, Blood tests, Chest X-ray

COVID-19 Treatment

• Antiviral drugs (Lopinavir, Ribavirin, interferon beta-1b), corticosteroids (dexamethasone, prednisolone), Immunomodulator (tocilizumab)

COVID-19 Prevention

• Wear facemasks
• Cover coughs/sneezes
• Frequent handwashing
• Social distancing
• Quarantine

Fungal Pneumonia

Fungal Pneumonia: Introduction

• Fungal pneumonia is a lung infection caused by either primary pathogenic or opportunistic fungi.
• Pathogenic fungi can infect both healthy and immunocompromised individuals.
• Mortality can be very high (90%) in immunocompromised patients, while normal immune systems often respond well to antiviral therapy.

Fungal Pneumonia: Transmission

• Inhalation of fungal spores is the typical method of transmission.
• Pathogenic examples include: Histoplasma capsulatum (histoplasmosis), Coccidioides immitis (coccidioidomycosis), Blastomyces dermatitidis (blastomycosis), Paracoccidioides brasiliensis (paracoccidioidomycosis) - all thermally dimorphic fungi.
• Fungal infections are geographically specific (e.g., Histoplasmosis, Coccidioidomycosis).

Fungal Pneumonia: Histoplasmosis

• Caused by Histoplasma capsulatum.
• Often associated with the Ohio river valley.
• Dimorphic (yeast form and mycelial form depending on temperature).
• Typically a mild, self-limiting disease, but can be severe in immunocompromised individuals.

Fungal Pneumonia: Coccidioidomycosis

• Caused by Coccidioides immitis.
• Endemic to Southwestern U.S. and northern Mexico.
• Distinctive morphology (block-like arthrospores, spherules containing endospores in the lungs).
• Lung infection is common, but dissemination to the central nervous system (meningitis) can occur.

Fungal Pneumonia: Blastomycosis

• Caused by Blastomyces dermatitidis.
• Native to North America.
• Generally occurs in pulmonary form, but can cause skin or bone infections.
• Dimorphic characteristic.

Fungal Pneumonia: Paracoccidioidomycosis

• Caused by Paracoccidioides brasiliensis.
• Found in Central and South America.
• Lung infection followed by lesions and other problems and is typically restricted to the mucosa of the mouth and nose.

Fungal Pneumonia: Opportunistic Fungi

• Pneumonia caused by opportunistic fungi is rising due to immunosuppressive drugs after organ transplant, cytotoxic drugs in cancer therapy, and a proliferation of AIDS patients globally.
• Includes Candida albicans (oral thrush, systemic candidiasis), Aspergillus species (aspergillosis, fungus ball), Cryptococcus neoformans (cryptococcosis), Pneumocystis jiroveci (pneumonia).

Fungal Pneumonia: Diagnosis and Treatment

• Diagnosis: microscopic examination of sputum (silver staining), Bronchoalveolar lavage (BAL), cultures (Sabouraud dextrose agar), molecular methods (PCR), serologic testing (ELISA), skin testing
• Treatment: depends on the causative agent (e.g., antifungals like amphotericin B, fluconazole).

Prevention of Viral and Fungal Pneumonia

• Handwashing, covering coughs/sneezes, quarantining
• Avoid touching eyes, nose, and mouth with unwashed hands.