Respiratory Infections: Symptoms, Causes, and Treatment
BCG Vaccine
Full Form: Bacillus Calmette-Guérin vaccine.
Purpose: Prevents tuberculosis (TB), especially severe forms like miliary TB and tuberculous meningitis in children.
Type: Live attenuated vaccine derived from Mycobacterium bovis.
Administration:
- Route: Intradermal.
- Site: Deltoid region of the left arm.
- Age: At birth or within the first year.
Mechanism: Induces cellular immunity (T-cell response).
Adverse Effects: Local swelling, ulcer formation, regional lymphadenopathy, keloid scar.
Contraindications: Immunocompromised individuals (e.g., HIV patients).
MDR-TB
Definition: Multi-Drug Resistant TB refers to TB resistant to at least isoniazid (INH) and rifampicin, the two first-line anti-TB drugs.
Causes:
- Incomplete or irregular treatment.
- Poor drug compliance.
- Misuse of anti-TB drugs.
Symptoms: Persistent cough, hemoptysis, weight loss, fever, night sweats, weakness.
Diagnosis:
- GeneXpert (detects rifampicin resistance).
- Line Probe Assay (LPA).
- Culture and Drug Sensitivity Testing (DST).
Treatment:
- Use of second-line drugs like fluoroquinolones (levofloxacin, moxifloxacin), aminoglycosides, and newer drugs like bedaquiline.
- Treatment duration: 18-24 months.
Prevention: Adherence to Directly Observed Treatment Short-course (DOTS), infection control measures, and monitoring of patients.
Mycoplasma Pneumonia
Causative Agent: Mycoplasma pneumoniae (lacks a cell wall).
Transmission: Airborne respiratory droplets, common in crowded places.
Symptoms: Gradual onset of dry cough, fever, malaise, and sore throat. Headache, fatigue, myalgia.
Diagnosis:
- PCR: Detects bacterial DNA.
- Serology: Detects IgM/IgG antibodies.
- Chest X-ray: Shows interstitial infiltrates (atypical pneumonia).
Treatment:
- Macrolides (e.g., azithromycin).
- Tetracyclines (e.g., doxycycline) for adults.
- Fluoroquinolones as alternatives.
Complications: Hemolytic anemia, myocarditis, neurological issues like encephalitis.
Pulmonary Anthrax
Cause: Bacillus anthracis (Gram-positive, spore-forming rod).
Transmission: Inhalation of spores (woolsorter’s disease).
Pathogenesis: Spores enter lungs, germinate, produce toxins, and cause severe damage.
Symptoms:
- Initial: Flu-like symptoms (fever, cough, fatigue).
- Later: Severe respiratory distress, cyanosis, shock, widened mediastinum on X-ray.
Diagnosis:
- Microscopy: Gram stain of sputum.
- Culture: Blood culture.
- PCR and serology.
Treatment:
- Antibiotics: Ciprofloxacin or doxycycline.
- Antitoxin therapy.
Prevention: Vaccination for high-risk individuals and proper handling of animal products.
Streptococcal Pharyngitis
Causative Agent: Streptococcus pyogenes (Group A beta-hemolytic streptococcus).
Transmission: Droplet infection or direct contact.
Symptoms: Sore throat, fever, tonsillar exudates, tender cervical lymphadenopathy. Absence of cough (suggestive of bacterial cause).
Diagnosis:
- Rapid Antigen Detection Test (RADT).
- Throat culture (gold standard).
Treatment:
- Penicillin V or amoxicillin.
- Alternatives: Cephalosporins or macrolides for penicillin allergy.
Complications: Rheumatic fever, post-streptococcal glomerulonephritis.
Infectious Mononucleosis
Definition: A viral infection caused primarily by Epstein-Barr Virus (EBV), belonging to the herpesvirus family. It is also called the “kissing disease” due to transmission via saliva.
Mode of Transmission: Saliva (most common), sharing utensils, kissing, or close contact. Rarely through blood transfusion or organ transplant.
Pathogenesis: EBV infects B lymphocytes by binding to the CD21 receptor. Infected B-cells activate T-cells, leading to proliferation of atypical lymphocytes. The immune response causes the characteristic symptoms.
Symptoms:
- Fever.
- Sore throat with tonsillar enlargement.
- Cervical lymphadenopathy (swollen lymph nodes).
- Fatigue and malaise.
- Splenomegaly (enlarged spleen).
- Hepatomegaly (less common).
- Palatal petechiae.
Diagnosis:
- Monospot Test: Detects heterophile antibodies (specific for EBV).
- Peripheral Blood Smear: Presence of atypical lymphocytes (large reactive T-cells).
- Serology: IgM antibodies against EBV viral capsid antigen.
Treatment:
- Supportive care: Rest, hydration, analgesics (e.g., acetaminophen).
- Avoid contact sports.
- Steroids for severe complications.
Complications: Splenic rupture, hepatitis, hemolytic anemia, chronic fatigue syndrome, secondary bacterial infections like streptococcal pharyngitis.
Mumps
Causative Agent: Mumps virus, a member of the Paramyxovirus family.
Mode of Transmission: Respiratory droplets from infected individuals, contact with saliva.
Pathogenesis: Virus enters through the respiratory tract and infects the parotid glands via viremia (virus in the blood). It can spread to other organs like testes, ovaries, pancreas, and the CNS.
Symptoms:
- Fever, headache, malaise.
- Painful parotid gland swelling (unilateral or bilateral).
- Difficulty chewing or swallowing.
- Orchitis (testicular inflammation) in post-pubertal males.
- Oophoritis in females (ovarian inflammation).
- Aseptic meningitis (rare complication).
Diagnosis:
- Clinical features: Swelling of parotid glands.
- RT-PCR: Detects viral RNA in saliva or blood.
- Serology: IgM antibodies against mumps virus.
Treatment:
- Supportive care: Rest, hydration, analgesics.
- Orchitis: Scrotal support, ice packs, pain relief.
Prevention: MMR Vaccine (Measles, Mumps, Rubella): Live attenuated vaccine given at 9-12 months and booster at 15-18 months.
H1N1 / Swine Flu
Cause: Influenza A virus subtype H1N1 (genetic reassortment between avian, swine, and human influenza viruses).
Mode of Transmission: Respiratory droplets (coughing/sneezing), contact with contaminated surfaces.
Symptoms:
- Fever, chills, sore throat, cough.
- Fatigue, myalgia, headache.
- Vomiting and diarrhea (common in children).
Diagnosis:
- RT-PCR: Detects viral RNA in nasopharyngeal swabs.
- Rapid antigen tests.
Treatment:
- Antivirals: Oseltamivir (Tamiflu), Zanamivir.
- Supportive care: Fluids, rest, antipyretics.
Prevention: Influenza vaccination, hand hygiene, respiratory etiquette (covering mouth/nose while coughing or sneezing).