Viral Disease

Mealses(Rubella)

Virus

• RNA virus

• Family: Paramyxoviridae

• Humans only reservoir

Transmission

• Inhalation of respiratory droplets

Incubation Period

• 10–14 days

Pathogenesis

• Virus enters respiratory epithelium

• Replicates → spreads via bloodstream

• Infects endothelial cells

• Rash due to T-cell immune response

Clinical Features

• Prodrome:

• Fever

• Cough

• Coryza

• Conjunctivitis

• Koplik spots: bluish-white spots on buccal mucosa (diagnostic)

• Rash: Maculopapular starts on face → spreads downward

Complications

• Ear infection

• Pneumonia

• Encephalitis

• Subacute sclerosing panencephalitis (SSPE)

Diagnosis

• IgM antibodies

• RT-PCR from throat or nasopharyngeal samples

Rubella (GERMAN MEASLES)

Virus

• RNA virus (Togaviridae)

Transmission

• Respiratory droplets

• Transplacental (mother → fetus)

Clinical Features

• Mild fever

• Mild rash (face → body)

• Lymphadenopathy

• Often mild or asymptomatic

Congenital Rubella Syndrome

• Occurs if infection during pregnancy

• Causes:

• Eye abnormalities

• Congenital heart disease

• Jaundic and anemia

• Mental retardation

• Hepatosplenomegaly

• Thrombocytopenia

Diagnosis

• IgM antibodies

• PCR (nasopharyngeal or urine)

Parvovirus B19 (Fifth disease)-Erythema infectionsum-slapped cheek

Virus

• Small, non-enveloped, ssDNA virus

Transmission

• Respiratory droplets

Target Cells

• Erythroid precursor cells (bone marrow)

• Endothelial cells

Clinical Features

• “Slapped cheek” rash

• Lacy rash on body

• Mild fever

• Arthraitis (adults)

Complications

• Aplastic anemia

• Intrauterine infection can lead to:Severe anemia,Hydrops fetalis,massive edema,CHF

Diagnosis

• IgM antibodies

Reseola infantum-Exabthem subitum(Sixth disease)

Virus

• Human herpesvirus-6 (HHV-6)

Target children

Transmission

• Respiratory droplets

Clinical Features

• Begins with high fever for 3–5 days

• Sudden defervescence → rash appears

• Pink maculopapular rash

• Mild lymphadenopathy

Outcome

• Complete recovery

Varicella Zoster/shingles Virus-Chickenpox

Virus

• Varicella(primary illness)Zoster(recurrent form/latent)Virus (VZV)

• DNA herpesvirus

Transmission

• Airborne droplets

• Direct contact

Pathogenesis

• Primary infection in respiratory tract

• Viremia → skin

• Virus remains (latent) in dorsal root ganglia

Clinical Features

• Latency (most important characterstic)

• Crops of lesions in different stages:

• Macule → papule → vesicle → crust

Starts on trunk → spreads to face and limbs (it’s very painful)

Vaccine:Varivax and zostervax

• Herpes Simples Virus-1 infection

Virus

• Double-stranded DNA virus

Transmission

•By Direct contact

• By Saliva

Primary Infection

• Gingivostomatitis

• Pharyngitis

• Keratoconjunctivitis

• Encephalitis (severe)

Reactivation(Recurrent infection):due to latent virus in the trigemnial ganglion:

• Cold sores (herpes labialis):around the lips

• Keratitis:lead to blindness

Clincal features:

• Vesicles and ulcers on tips pf the fingers

• Keratitis

• Encephalitis

HAND, FOOT AND MOUTH DISEASE (HFMD)

Virus

• Coxsackievirus A16

• Enterovirus 71

Transmission

• Oral ingestion

Clinical Features

• Fever

• Painful oral ulcers

• Vesicular rash on hands, feet, buttocks