🦠 Respiratory Viral Diseases & 🧴 Skin / Contact Viral Diseases

Common Cold

Causative Agent: Rhinovirus
Family: Picornaviridae
Genome: ssRNA
Envelope: Naked
Symptoms: Runny nose, sore throat, sneezing, mild cough
Transmission: Respiratory droplets, contact with contaminated objects
Treatment: Supportive care
Prevention: Handwashing, hygiene
Notes: Causes 30–50% of colds; >200 strains exist.

Influenza (Flu)

Causative Agent: Influenza virus A, B, or C
Family: Orthomyxoviridae
Genome: Segmented ssRNA (-)
Envelope: Enveloped
Symptoms: Fever, chills, muscle aches, cough, fatigue
Transmission: Airborne droplets
Treatment: Tamiflu (neuraminidase inhibitor)
Prevention: Annual A & B vaccine
Notes: A causes pandemics; B is seasonal; C is mild.

Parainfluenza Infection

Causative Agent: Human Parainfluenza Virus (HPIV 1 & 3)
Family: Paramyxoviridae
Genome: ssRNA (-)
Envelope: Enveloped
Symptoms: Fever, cough, nasal congestion
Transmission: Respiratory droplets, contact
Treatment: Supportive care
Prevention: Hygiene
Notes: Usually mild, lower respiratory tract infection.

Respiratory Syncytial (RS) Disease

Causative Agent: Respiratory Syncytial Virus (RSV)
Family: Paramyxoviridae
Genome: ssRNA (-)
Envelope: Enveloped
Symptoms: Cough, wheezing, bronchiolitis, pneumonia
Transmission: Droplets, contact with contaminated surfaces
Treatment: Supportive; monoclonal antibodies for infants
Prevention: RSV vaccine for adults, antibody for infants
Notes: Leading cause of infant hospitalization in U.S.

(SARS) Severe Acute Respiratory Syndrome

Causative Agent: SARS coronavirus (SARS-CoV-1)
Family: Coronaviridae
Genome: ssRNA (+)
Envelope: Enveloped
Symptoms: High fever, cough, pneumonia, shortness of breath
Transmission: Respiratory droplets, contact with surfaces
Treatment: Supportive
Prevention: Hygiene, avoiding contact
Notes: Originated from bats; disappeared after 2004.

Hantavirus Pulmonary Syndrome

Causative Agent: Hantavirus
Family: Bunyaviridae
Genome: ssRNA (-)
Envelope: Enveloped
Symptoms: Fever, muscle aches, lung edema, respiratory failure
Transmission: Inhalation of aerosolized rodent urine/feces/saliva
Treatment: Supportive care, oxygen therapy
Prevention: Rodent control, PPE during cleanup
Notes: ~35% mortality rate; BSL-4 pathogen.

Cold Sores

Causative Agent: Herpes Simplex Virus Type 1 (HSV-1)
Family: Herpesviridae
Genome: dsDNA
Envelope: Enveloped
Symptoms: Painful blisters around mouth
Transmission: Direct contact with lesions/saliva
Treatment: Acyclovir
Prevention: Avoid contact during outbreak
Notes: Latent in nerve cells; reactivates periodically.

Genital Herpes

Causative Agent: Herpes Simplex Virus Type 2 (HSV-2)
Family: Herpesviridae
Genome: dsDNA
Envelope: Enveloped
Symptoms: Itching, blisters in genital area
Transmission: Sexual contact, birth transmission
Treatment: Acyclovir
Prevention: Safe sex, antivirals during pregnancy, C-section if active
Notes: Latent infection; lifelong.

Chickenpox (Varicella)

Causative Agent: Varicella-Zoster Virus (VZV)
Family: Herpesviridae
Genome: dsDNA
Envelope: Enveloped
Symptoms: Red itchy rash → fluid vesicles → scabs
Transmission: Respiratory droplets, skin contact
Treatment: Acyclovir (severe cases)
Prevention: Varicella vaccine
Notes: Can cause serious complications in adults or immunocompromised.

Shingles (Zoster)

Causative Agent: Reactivated Varicella-Zoster Virus
Family: Herpesviridae
Genome: dsDNA
Envelope: Enveloped
Symptoms: Painful rash on one side of body
Transmission: Reactivation of latent virus
Treatment: Acyclovir
Prevention: Zostavax or Shingrix vaccine
Notes: Pain may persist (postherpetic neuralgia).

Measles (Rubeola)

Causative Agent: Measles virus
Family: Paramyxoviridae
Genome: ssRNA (-)
Envelope: Enveloped
Symptoms: Fever, cough, red eyes, Koplik spots, red rash
Transmission: Respiratory droplets
Treatment: Supportive
Prevention: MMR vaccine
Notes: Highly contagious; can cause pneumonia or encephalitis.

Mumps

Causative Agent: Mumps virus
Family: Paramyxoviridae
Genome: ssRNA (-)
Envelope: Enveloped
Symptoms: Swollen parotid glands, fever, headache
Transmission: Droplets or contact
Treatment: Supportive
Prevention: MMR vaccine
Notes: May cause meningitis or infertility in males.

Rubella (German Measles)

Causative Agent: Rubella virus
Family: Togaviridae
Genome: ssRNA (+)
Envelope: Enveloped
Symptoms: Mild fever, rash from face → body
Transmission: Respiratory droplets or contact
Treatment: Supportive
Prevention: MMR vaccine
Notes: Dangerous in pregnancy (birth defects).

Warts (Human Papillomavirus)

Causative Agent: Human Papillomavirus (HPV)
Family: Papillomaviridae
Genome: dsDNA
Envelope: Naked
Symptoms: Painless warts (common, plantar, genital)
Transmission: Direct contact or contaminated surfaces
Treatment: Removal (cryotherapy); no antiviral
Prevention: Gardasil vaccine (HPV 6, 11, 16, 18)
Notes: Some strains are oncogenic (cause cervical cancer).

Smallpox (Variola)

Causative Agent: Variola virus
Family: Poxviridae
Genome: dsDNA
Envelope: Enveloped
Symptoms: Fever, macules → papules → vesicles → pustules → pitted scars
Transmission: Respiratory droplets, skin contact
Treatment: None (eradicated)
Prevention: Smallpox vaccine
Notes: ~30% fatality rate; eradicated in 1980; potential bioterrorism threat.