Viral infection 3

Viral infection3

Dr Anfal layth
Arab board of dermatology

Viral exanthemas

An exanthem is defined as a skin eruption occurring as a sign of a general disease.
Viral exanthems may present with distinctive cutaneous features or in an entirely nonspecific fashion
Enanthems: rash on mucous membrane.

Incubational period

Prodromal
Enanthem
Exanthem
Fade


The clinical types of viral exanthems
Viral exanthema

Differential diagnosis of morbilliform eruption

Viral infection: Measles, rubella, roseola, infectious mononucleosis
Bacterial infection: Scarlet fever
Reactive erythema: Urticaria, erythema multiforme
Drug eruption: Ampicillin, barbiturate, NSAIDs

MEASLESSynonym: ■ Rubeola

Measles is caused by an RNA virus in the Paramyxoviridae family
Humans are the natural host and reservoir of infection
Incidence greatly decreased with vaccination

pathogenesis

The incubation period of measles, which is highly contagious and spread via respiratory droplets, is 10–14 days
Target populations were unvaccinated children younger than 5 years of age
replication of the virus within the epithelial cells of the respiratory tract spread to the lymphoid tissue and blood, resulting in viremia.
The virus can then disseminate to internal organs, including the lungs, liver, and gastrointestinal tract.

Clinical feature

Measles classically presents with a prodrome of fever, cough, nasal congestion, and rhinoconjunctivitis.
A pathognomonic enanthem, Koplik spots, appears during the prodrome and is composed of gray– white papules on the buccal mucosa.
The exanthem develops over 2–4 days and consists of erythematous macules and papules that begin on the forehead, hairline, and behind the ears and then spread in a cephalocaudad direction
On the fifth day, the exanthem starts to fade in the same order as it appeared.

Treatment:

1. Symptomatic: bed rest, antipyretics, analgesics.
2. High dose vitamin A.
3. Vaccination at 15 months.
4. Immunoglobulin.

Rubella(German measles)(3 days measles)

Rubella is caused by an RNA virus in the Togaviridae family
The disease is spread via respiratory droplets,
with an incubation period of 16–18 days.

Clinical features

Rubella typically presents with a mild prodrome that includes fever, headache, and upper respiratory symptoms. In children, many cases are subclinical.
One to 5 days following the prodrome, an eruption of erythematous macules and papules appears on the face, spreading in a cephalocaudad direction.
Erythematous petechial macules may also be present on the soft palate (Forchheimer spots).
The eruption is often accompanied by tender lymphadenopathy, especially of the occipital, posterior auricular, and cervical regions.
The cutaneous eruption tends to fade in 2–3 days in the same order as it appeared


Note
Rubella during pregnancy (1st trimester) associated with congenital abnormalities in the fetus in the form of cataract, cardiac defect and deafness.

Treatment and prevention

Treatment of rubella is supportive.
The current recommended immunization schedule for rubella vaccine, which is given in conjunction with the measles and mumps vaccines (MMR vaccine), is an initial dose at 12–15 months and a second dose at 4–6 years16

Characteristics

Measles
Rubella
Etiology

Paramyxovirus

Togavirus
I.P.


10 days
2-3 wks
Route of transmission

Respiratory droplet

Respiratory droplet
Prodrome

High fever, malaise, cough, coryza, sneezing, conjunctivitis, adenopathy

Absent or mild or low grade fever, upper respiratory symptoms, adenopathy & eye pain
Exanthems
Onset
7 days after prodrome
5 days after prodrome

Shape

Large, coalescing morbilliform rashes
Small morbilliform or scarlet-like lesion

Distribution

Forehead & behind ear; extend centrifugally & caudally in 3 days; fade in same manner
Forehead & behind ear; extend centrifugally & caudally in 1 day; fade in same manner


Duration
Last 7 days
Last 3 days
Enanthems
Name
Koplik’s spot
Forscheimer’s sign

Shape

White papules on red base
Tiny red macules or petechiae

Site

Buccal mucosa
Soft palate & uvula
Complication

Otitis media, pneumonia, encephalitis, thrombocytopenia

Arthritis & congenital rubella infection syndrome if occur in 1st trimester of pregnancy

ERYTHEMA INFECTIOSUMFifth disease ■ “Slapped cheek” disease ■ Parvovirus B19 infec

Human parvovirus B19 (B19), the only parvovirus known to infect humans, it is small single-stranded DNA virus
peak incidence of erythema infectiosum during the winter and spring.
Age of patient: children


Clinical features
Mild prodromal symptoms such as a low-grade fever, myalgias, and headache may develop 7–10 days before the characteristic exanthem appears
initial stage of the exanthem consists of bright red macular erythema of the cheeks, with sparing of the nasal bridge and circumoral regions Slapped check stage
One to 4 days later, the second stage appears as erythematous reticulated pattern on extermities lasts 1–3 weeks Lacy erythema stage
Recurrent stage : after completely resolution of the condition in 5-6 days, child develop recurrent facial erythema after exposure to heat or sun

Roseola infantumExanthem subitum ■ Sixth disease

is a common febrile illness of infancy that is primarily caused by human herpesvirus-6 (HHV-6) infection and is occasionally associated with human herpesvirus-7 (HHV-7) infection
Age of patient: infant
Clinical picture: infant suffer from prodrome of high fever & lymphadenopathy for 4 days.
In the fourth day fever suddenly drop & morbilliform exanthems appear distributed on the trunk.
The rash will disappear completely in two days
treatment supportive

Hand, foot and mouth disease

Caused: coxsackie A16 virus
This disorder is characterized by a vesicular eruption on the palms and soles in conjunction with an erosive stomatitis.
Oral lesions: consist of small vesicles which rapidly ulcerate surrounded by erythema.
Hand and feet lesions: are red papules which quickly become small gray vesicles with red halo, oval and run parallel with skin line.
Lesions improve spontaneously and treatment is supportive

Herpangina

Acute infectious illness.
Cause: coxsackie virus (group A).
Age: child.
Clinical picture: A child presented with fever and severe sore throat, covered with many small vesicles, which rapidly become superficial ulcers.
The episode resolve in about a week