EXANTHEM SUBITUM Sixth disease ROSEOLA INFANTUM EXANTHEM SUBITUM Sixth disease

Epidemiology caused by human herpesvirus (HHV) type 6 (HHV-6) for<2yrs old 80% of cases; and less frequent in 10-30% of cases by HHV-7 in older than 2 yr. Are DNA viruses, which are of the herpesvirus family 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 with the remission of fever. The rash usually lasts 1 to 2 days but may fade rapidly 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

ERYTHEMA INFECTIOSUM FIFTH DISEASE

Epidemiology caused by the human parvovirus B19 Single stranded DNA virus. Benign self-limited illness affecting any age mostly 5-15 yrs old and even adults . Incubation period average 15-17 days .It is transmitted by respiratory secretions airborne route. 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 even 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 within few days (Erythema Infectiosum). The rash appears in two stages A. erythematous cheeks, appearing as a "slapped cheek" rash

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

4.Main abnormalities occur in CBC with parvovirus infection, includes low reticulocyte count and anemia due to low RBCs production by bone marrow; which may be mild anemia or may be severe called : aquired pure red cell anemia, or in pregnancy ; fetal anemia and hydrops fetalis. Investigations includes CBC showing; Low RBC count and; Low Reticulocyte count; and Parvovirus B19 can be detected by PCR .

Treatment There is no specific therapy. Routine supportive care. Transfusions may be required for ; transient aplastic crisis in pt. with hemolytic diseases or in ; aquired pure red cell anemia. Intrauterine transfusion has been performed for hydrops fetalis associated with fetal parvovirus B19 infection.

CHICKENPOX

VARICELLA-ZOSTER VIRUS INFECTION

Chickenpox DNA virus that is a member of the herpesvirus family Humans are the only natural host. VZV (chickenpox) is highly communicable among susceptible individuals. It is mild disease in young children but may be severe in adult and in immunocompromised children Chickenpox pt. and pt with zoster lesion (shingles) infect susceptible child leading to chicken pox illness. the period of infectivity to others; 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 5 to 10 yr. peak seasonal infection in late winter and spring Transmission is airborne route by inhalation of the virus; by direct contact with the lesions before dried or crusted, or by air droplet from sneezing or coughing of the patient in the catarrhal stage.

Clinical Manifestations The incubation period of varicella is generally 14 to 16 days Prodromal symptoms of fever, malaise, and anorexia, running nose may precede the rash by 1 day The characteristic rash appears initially as small red papules that rapidly progress to oval, "teardrop" vesicles on an erythematous base and in crops (different lesions) of lesions: papules and vesicles. The fluid progresses from clear to cloudy, and the vesicles ulcerate, crusted, and dried 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., with all stages of lesions being present at the same time(crop). Pruritus is universal. Periods of illness is about 1-2 weeks . Shingles(herpes zoster) is recurrence of VZV infection in previously infected child.

congenital varicella Fetal varicella during first 6 months of pregnancy includes followings pathological effects: low birth wt, cortical brain atrophy, mental retardation, cataract, microcephaly, 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. ANTIVIRAL(acyclovir) THERAPY indicated ;IN infected : 1.immunocompromised persons, 2.adult above 15 yrs 3.neonates less than 28 days old of un- immunized mother, and in premature baby whatever the mother immunity; because the baby will not receive immunity from mother and his illness will be severe

Complications 1.Varicella is a more severe disease for neonates, adults, and immunocompromised persons. 2.Secondary infection of skin lesions by streptococci or staphylococci is the most common complication

3.hemorrhagic lesions may occur, known as varicella gangrenosa 4.Pneumonia is uncommon in healthy children, but may occurs in 15% to 20% of healthy adults and in immunecompromised persons . 5.Reye syndrome when aspirin used . 6. Encephalitis and postinfectious cerecbellar ataxia , Guillain-Barrie syndrome

Prevention Varicella vaccine is live attenuated , is recommended for routine administration to children with 2 doses: at 12 mo and at 4–6 yr of age.

4.Adult and ages 15 yr and older, who are exposed to infection. Prevention con. Passive immunity can be provided by VZIG, which is indicated within72 hours of exposure to infected pt. in those individuals at increased risk for severe illness, including: 1.immunocompromised persons, 2. neonates of infected mothers who had onset of chickenpox within 5 days before delivery or 48 hours after delivery to prevents getting infection because it will be severe and may be fatal. 3.Newborn of un-imunized mother and premature baby. Newborn of mother with previous imunity, will be protected and no needs for VZIG if exposed to pt. 4.Adult and ages 15 yr and older, who are exposed to infection.