EXANTHEM SUBITUM Sixth disease ROSEOLA INFANTUM EXANTHEM SUBITUM Sixth disease

Epidemiology caused by human herpesvirus (HHV) type 6 (HHV-6) for 6-18 months old; and 10-30% of cases by HHV-7 in older than 2 yr. Are large, enveloped double-stranded DNA viruses, which are of the herpesvirus family Transplacental antibody protects most infants until 6 months of age HHV-6 is a major cause of acute febrile illnesses in infants and may be responsible for 20% of visits to the emergency department for children 6 to 18 months old.

Clinical Manifestations Roseola is characterized by high fever (often ≥40°C) lasting 3 to 4 days followed by maculopapular, rose-colored pruritic rash that appears coincident with the remission of fever. The rash usually lasts 1 to 2 days but may fade rapidly Most children with roseola are irritable and appear toxic. Roseola is associated with approximately one third of febrile seizures

Treatment There is no specific therapy for roseola. Routine supportive care includes maintaining adequate hydration and antipyretics The prognosis for roseola is excellent. A few deaths have been attributed to HHV-6, usually in cases complicated by encephalitis

ERYTHEMA INFECTIOSUM FIFTH DISEASE

Epidemiology caused by the human parvovirus B19 Single stranded DNA virus. Benign self-limited illness. . incubation period average 15-17 days it an important cause of aplastic crisis in patients with hemolytic anemias like thalassemia, sickle anemia,& spheroytosis. Parvovirus B19 also causes severe fetal anemia and hydrops fetalis after primary infection during pregnancy

Clinical Manifestations usually begin with a mild prodromal nonspecific illness characterized by low grade fever, malaise, myalgias, and headache. This illness is followed by the characteristic rash 7 to 10 days later Erythema Infectiosum). The rash appears in three stages 1. erythematous cheeks, appearing as a "slapped cheek" rash

2.After 1-4 days an erythematous symmetric, maculopapular, involves trunk and limbs rash appears. 3. later central clearing takes place in the rash, giving a distinctive lacy, reticulated rash that lasts 1-3 weeks. This rash may be pruritic, does not desquamate – and it waxes and wanes with exposure to sunlight, heat, exercise and stress. .

Investigation In Parvovirus infections Many abnormalities occur in CBC with parvovirus infection lasts7-10 days , including reticulocytopenia , mild anemia, thrombocytopenia, lymphopenia, and neutropenia. Parvovirus B19 can be detected by PCR .

Treatment There is no specific therapy. Routine supportive care includes maintaining adequate hydration and antipyretics. Transfusions may be required for transient aplastic crisis. Intrauterine transfusion has been performed for hydrops fetalis associated with fetal parvovirus B19 infection. IV immunoglobulin may be used for infected immunocompromised persons with severe anemia.

CHICKENPOX

VARICELLA-ZOSTER VIRUS INFECTION

VZV (chickenpox) is highly communicable among susceptible individuals. double-stranded DNA virus that is a member of the herpesvirus family Humans are the only natural host. VZV (chickenpox) is highly communicable among susceptible individuals. Varicella v.(chickenpox) and zoster v.(shingles) infect susceptible child leading to chicken pox. the period of communicability ranges from 2 days before to 7 days after the onset of the rash till when all lesions are crusted and dried.

Epidemiology the peak age of occurrence was 5 to 10 years peak seasonal infection in late winter and spring Transmission is by direct contact, and air droplet.

Clinical Manifestations The incubation period of varicella is generally 14 to 16 days Prodromal symptoms of fever, malaise, and anorexia may precede the rash by 1 day The characteristic rash appears initially as small red papules that rapidly progress to nonumbilicated, oval, "teardrop" vesicles on an erythematous base. The fluid progresses from clear to cloudy, and the vesicles ulcerate, crust, and heal.

New crops appear in 3 to 4 days, usually beginning on the trunk followed by the head, the face, and, less commonly, the extremities. There may be a total of 100 to 500 lesions, with all stages of lesions being present at the same time. Pruritus is universal and marked. Shingles is recurrence of VZV infection in previously infected person

congenital varicella Fetal varicella during first 6 months of pregnancy includes followings pathological effects: low birth wt, cortical brain atrophy, mental retardation, cataract, microcephaly, or hydrocephalus intracranial calcification, cicatrical scarring of body and limbs with aplasia of fingers and toes .

Treatment Symptomatic therapy of varicella includes nonaspirin antipyretics, cool baths, and careful hygiene. In immunocompromised persons, and in adult ,and in neonates without mother immunity; early therapy with acyclovir if they get infected, and VZIG given early if they exposed to a pt. (because of severe infection in them). Children 1 month -12years (mild) ; no need for VZIG or Antivirus.

Neonatal varicella . Fullterm newborn gets rash of infection 10 -12 days after birth is severe and gets the virus at last 3 wk of pregnancy; needs acyclovir because of low immunity from mother. Fullterm newborn exposed to an infected pt. needs VZIG only if the mother is seronegative (otherwise it is mild if she is seropositive); and also for Premature NB less than 28 wk gestation with any immune status of the mother. Newborn of mother who developed rash of varicella between 5-days before and 2 days after delivery develops varicella at 10-12 days of life and is 20-30%fatal ; needs VZIG within 96 of exposure

Complications Varicella is a more severe disease for neonates, adults, and immunecompromised persons. Secondary infection of skin lesions by streptococci or staphylococci is the most common complication

Thrombocytopenia and hemorrhagic lesions may occur, known as varicella gangrenosa Pneumonia is uncommon in healthy children, but may occurs in 15% to 20% of healthy adults and in immunecompromised persons . Myocarditis, pericarditis, orchitis, hepatitis, ulcerative gastritis, glomerulonephritis, and arthritis may complicate varicella

Reye syndrome may follow varicella; specially if aspirin used during the illness, so aspirin is contraindicated during varicella infection. Neurologic complications frequently include post-infectious encephalitis, Guilain-barre syn ,and cerebellar ataxia.

Prevention Varicella vaccine is live attenuated , is recommended for routine administration to children with 2 doses: at 12–15 mo and at 4–6 yr of age. vaccination with a second dose is recommended for children and adolescent when exposed, who received only 1 dose. It should be administered in different site if given together with MMR. Children without immunization can take 2 doses with 4 weeks apart.

15 yr and older, who are exposed to infection. Prevention con. Passive immunity can be provided by VZIG, which is indicated within 96 hours of exposure for susceptible individuals at increased risk for severe illness, including immunocompromised persons, neonates of infected mothers who had onset of chickenpox within 5 days before delivery or 48 hours after delivery, premature baby less than 28 wk gestation and children 15 yr and older, who are exposed to infection.