viral exanthem

measles (rubeola)
measles virus is an rna virus. the biologic features of measles that suggest the possibility that measles might be eradicated are (1) a distinctive rash as a sentinel marker (2) no animal reservoir (3) no vector (4) seasonal occurrence with disease-free periods (5) no transmissible latent virus (6) one serotype and (7) an effective vaccine. measles is highly contagious approximately 90% of susceptible household contacts acquire the disease. maximal dissemination of virus occurs by dropinglet spray during the prodromal period (catarrhal stage).clinical manifestations
measles has three clinical stages: an incubation stage, a prodromal stage, and a final stage with a maculopapular rash accompanied by high fever. the incubation period lasts approximately 10–12 days. the prodromal phase usually lasts 3–5 days and is characterized by a low-grade to moderate fever, a dry cough, coryza, and conjunctivitis. these symptoms precede the appearance of koplik spots by 2–3 days. koplik spots are grayish white dots, usually as small as grains of sand, that have slight, reddish areolae occasionally they are hemorrhagic. they tend to occur opposite the lower molars but may spread irregularly over the rest of the buccal mucosa. they appear and disappear rapidly, usually within 12–18hr.
the conjunctival inflammation and photophobia may suggest measles before koplik spots appear. the temperature rises abruptly as the rash appears and often reaches 40°c (104°f) or higher. in uncomplicated cases, as the rash appears on the legs and feet, the symptoms subside rapidly within about 2 days, usually with an abrupt droping in temperature to normal. patients up to this point may appear desperately ill, but within 24hr after the temperature dropings, they appear well.
the rash usually starts as faint macules on the upper lateral parts of the neck, behind the ears, along the hairline, and on the posterior parts of the cheek. the individual lesions become increasingly maculopapular as the rash spreads rapidly over the entire face, neck, upper arms, and upper part of the chest within approximately the first 24hr. during the succeeding 24hr the rash spreads over the back, abdomen, entire arm, and thighs. as it finally reaches the feet on the 2nd–3rd day, it begins to fade on the face. the rash fades downward in the same sequence in which it appeared. the severity of the disease is directly related to the extent and confluence of the rash. the rash is often slightly hemorrhagic, and itching is generally slight. as the rash fades, branny desquamation and brownish discoloration occur and then disappear within 7–10 days. lymph nodes at the angle of the jaw and in the posterior cervical region are usually enlarged, and slight splenomegaly may be noted.
diagnosis
the diagnosis is usually apparent from the characteristic clinical picture laboratory confirmation is rarely needed.
differential diagnosis
the rash of rubeola must be differentiated from that of rubella roseola infantum (human herpesvirus 6) infections resulting from echovirus, coxsackievirus, and adenovirus infectious mononucleosis toxoplasmosis meningococcemia scarlet fever rickettsial diseases kawasaki disease serum sickness and drug rashes.

treatment
treatment is entirely supportive. antipyretics (acetaminophen or ibuprofen) for fever, bed rest, and maintenance of an adequate fluid intake are indicated. humidification may alleviate symptoms of laryngitis or an excessively irritating cough it is best to keep the room comfortably warm rather than cool. patients with photophobia should be protected from exposure to strong light. bacterial complications of otitis media and bronchopneumonia require appropriate antimicrobial therapy.

vitamin a
vitamin a should be administered once daily for 2 days at
doses of 200,000 iu for children 12 mo of age or older 100,000 iu for
infants 6 mo through 11 mo of age and 50,000 iu for infants younger
than 6 mo of age.
complications
the case fatality rate is still 1–3/1,000 cases. the chief complications of measles are otitis media, pneumonia, and encephalitis. noma of the cheeks may occur in rare instances. gangrene elsewhere appears to be secondary to purpura fulminans or dic following measles. interstitial pneumonia may be caused by the measles virus (giant cell pneumonia). bacterial superinfection and bronchopneumonia are more frequent, however, usually with pneumococcus, group a streptococcus, staphylococcus aureus, and haemophilus influenzae type b. laryngitis, tracheitis, and bronchitis are common and may be due to the virus alone. measles may exacerbate underlying mycobacterium tuberculosis infection. myocarditis is an infrequent serious complication. neurologic complications are more common in measles than in any of the other exanthematous diseases. encephalitis and other central nervous system complications, including guillain-barré syndrome, hemiplegia, cerebral thrombophlebitis, retrobulbar neuritis, and subacute sclerosing panencephalitis occur rarely.
mumps: mumps virus, the cause of mumps, is an rna virus. the virus is spread by direct contact, airborne dropinglets, and fomites contaminated by saliva. transmission does not seem to occur more than 24hr before the appearance of the swelling or later than 3 days after it has subsided.
clinical manifestations: the incubation period ranges from 14–24 days, about one third of infections are subclinical. in children, prodromal manifestations are rare but may be manifest by fever and muscular pain (especially in the neck). the onset of salivary glands enlargement is usually characterized by pain and swelling in one or both parotid glands. the parotid swells characteristically with edema of the skin and soft tissues usually extends further and obscures the limit of the glandular swelling, so that the swelling is more readily appreciated by sight than by palpation, swelling usually peaks in 1–3 days. the swollen tissues push the earlobe upward and outward, and the angle of the mandible is no longer visible. swelling slowly subsides within 3–7 days but occasionally lasts longer. in approximately one quarter of cases the disease remains unilateral. the swollen area is tender and painful. although the parotid glands alone are affected in the majority of patients, swelling of the submandibular glands occurs frequently and usually accompanies or closely follows that of the parotid glands.
treatment: there is no specific antiviral therapy treatment is entirely supportive. antipyretics are indicated for fever, bed rest, and dietary advice. orchitis should be treated with local support and bed rest.
complications: cns: meningoencephalitis, aqueductal stenosis and hydrocephalus.
genitalia: orchitis and epididymitis and oophoritis.
others: pancreatitis, myocarditis, arthritis, thyroiditis, deafness, and optic neuritis.
roseola infantum (exanthem subitum, or sixth disease)
the primary infection with hhv-6, and less frequently hhv-7, causes the majority of cases of roseola. the incubation period averages 10 days. most adults excrete hhv-6 and hhv-7 in saliva and may serve as primary sources for virus transmission to children.
roseola is a mild febrile, exanthematous illness occurring almost exclusively during infancy. the peak incidence at 6–15 mo of age. transplacental antibodies likely protect most infants until 6 mo of age. the prodromal period of roseola is usually asymptomatic but may include mild upper respiratory tract signs.
clinical illness is generally heralded by high temperature, usually with an average of 39°c (103°f), most behave normally despite high temperatures. seizures may occur in 5–10% of children with roseola during this febrile period. infrequent complaints include rhinorrhea, sore throat, abdominal pain, vomiting, and diarrhea.
fever persists for 3–5 days, and then typically resolves rather abruptly (“crisis”). occasionally, the fever may gradually diminish over 24–36 hours (“lysis”). a rash appears within 12–24hr of fever resolution. the rash of roseola is rose colored, as the name implies, and is fairly distinctive. however, it may be confused with exanthems resulting from rubella, measles, or erythema infectiosum. the roseola rash begins as discrete, small (2–5mm), slightly raised pink lesions on the trunk and usually spreads to the neck, face, and proximal extremities. the rash is not usually pruritic. lesions typically remain discrete but occasionally may become almost confluent. after 1–3 days, the rash fades.
diagnosis
the most important reason for establishing the diagnosis of roseola is to differentiate this generally mild illness from other potentially more serious childhood rash illnesses such as measles. the diagnosis of roseola can be established primarily on the basis of age, history, and clinical findings.
treatment
children in the febrile, pre-eruptive phase of roseola usually are quite comfortable and require little supportive therapy. those children who are uncomfortable and irritable, or in whom histories of febrile convulsions exists, may benefit from treatment with acetaminophen or ibuprofen. adequate fluid balance should be maintained in all affected children. referral should be considered in those unusual circumstances in which serious disease develops, such as encephalitis, hepatitis, or pneumonitis.










scarlet fever
this disease is a result of infection by streptococci that elaborate one of three pyrogenic (erythrogenic) exotoxins. the incubation period ranges from 1-7 days, with an average of 3 days. the onset is acute and is characterized by fever, vomiting, headache, toxicity, pharyngitis, and chills. abdominal pain may be present when this is associated with vomiting before the appearance of the rash, an abdominal surgical condition may be suggested. within 12-48 hr, the typical rash appears.
generally, temperature increases abruptly, may peak at 39.6-40°c (103-104°f) on the 2nd day, and gradually returns to normal within 5-7 days in untreated patients it is usually normal within 12-24 hr after initiation of penicillin therapy. the tonsils are hyperemic and edematous and may be covered with a gray-white exudate. the pharynx is inflamed and covered by a membrane in severe cases. the tongue may be edematous and reddened. during the early days of illness, the dorsum of the tongue has a white coat through which the red and edematous papillae project (i.e., white strawberry tongue). after several days, the white coat desquamates the red tongue studded with prominent papillae persists (i.e., red strawberry tongue). the palate and uvula may be edematous, reddened, and covered with petechiae.
the exanthem is red, is punctate or finely papular, and blanches on pressure. in some individuals, it may be palpated more readily than it is seen, having the texture of gooseflesh or coarse sandpaper. the rash appears initially in the axillas, groin, and neck but within 24 hr becomes generalized. punctate lesions generally are not present on the face. the forehead and cheeks appear flushed, and the area around the mouth is pale (i.e., circumoral pallor). the rash is most intense in the axillas and groin and at pressure sites. petechiae may occur owing to capillary fragility. areas of hyperpigmentation that do not blanch with pressure may appear in the deep creases, particularly in the antecubital fossae (i.e., pastia s lines). in severe disease, small vesicular lesions (miliary sudamina) may appear over the abdomen, hands, and feet.
desquamation begins on the face in fine flakes toward the end of the 1st wk and proceeds over the trunk and finally to the hands and feet. the duration and extent of desquamation vary with the intensity of the rash it may continue for as long as 6 wk.
scarlet fever may follow infection of wounds (i.e., surgical scarlet fever), burns, or streptococcal skin infection. clinical manifestations including the strawberry tongue are similar to those just described, but the tonsils and posterior pharynx generally are not involved. a similar picture may be observed with certain strains of staphylococci that produce an exfoliative toxin, although a strawberry tongue is usually absent.
scarlet fever must be differentiated from other exanthematous diseases, including measles (characterized by its prodrome of conjunctivitis, photophobia, dry cough, and koplik spots), rubella (disease is mild, postauricular lymphadenopathy usually is present, and throat culture is negative), and other viral exanthems. patients with infectious mononucleosis have pharyngitis, rash, lymphadenopathy, and splenomegaly as well as atypical lymphocytes. the exanthems produced by several enteroviruses can be confused with scarlet fever, but differentiation can be established by the course of the disease, the associated symptoms, and the results of culture. roseola usually occurs in younger children and is characterized by the cessation of fever with the onset of rash and the transient nature of the exanthem. kawasaki disease, drug eruption, and tss must also be considered.
scarlet fever may be differentiated from kawasaki s disease by an older age at onset, absence of conjunctival involvement, and recovery of group a streptococci. arcanobacterium haemolyticum (formerly corynebacterium haemolyticum) also produces tonsillitis, pharyngitis (without a strawberry tongue), and a scarlatiniform rash in adolescents and young adults. severe sunburn can also be confused with scarlet fever.
treatment
gas is exquisitely sensitive to penicillin, and resistant strains have never been encountered. penicillin is, therefore, the drug of choice (except in patients who are allergic to penicillin) for pharyngeal infections as well as for suppurative complications. alternatives, including cehalosporines, erythromycin, and licomycin, but sulfonamides and the tetracyclines are not indicated for treatment of gas infections.
complications
suppurative complications from the spread of gas to adjacent structures were common before antibiotics became available. cervical lymphadenitis, peritonsillar abscess, retropharyngeal abscess, otitis media, mastoiditis, and sinusitis still occur in children in whom the primary illness has gone unnoticed or in whom treatment of the pharyngitis has been inadequate. gas pneumonia can also occur.
acute rheumatic fever and acute poststreptococcal glomerulonephritis are both nonsuppurative sequelae of infections with gas that occur after an asymptomatic latent period. they are both characterized by lesions remote from the site of the gas infection. acute rheumatic fever and acute glomerulonephritis differ in their clinical manifestations, epidemiology, and potential morbidity. in addition, acute glomerulonephritis can occur after a gas infection of either the upper respiratory tract or the skin, but acute rheumatic fever can occur only after an infection of the upper respiratory tract.
rubella
rubella (german or three-day measles) is an important childhood disease that is now very infrequent. rubella in early pregnancy may cause the congenital rubella syndrome. rubella virus is an rna virus. humans are the only natural host of rubella virus, which is spread either by oral dropinglet or transplacentally to the fetus, causing congenital infection. the peak incidence of rubella occurs among susceptible teenagers and young.
clinical manifestations
the incubation period is 14–21 days. the prodromal phase of mild catarrhal symptoms is shorter than that of measles and may be so mild that it goes unnoticed. approximately two thirds of infections are subclinical.
the most characteristic sign is retroauricular, posterior cervical, and postoccipital lymphadenopathy. no other disease causes the tender enlargement of these nodes to the extent that rubella does. an enanthem appears in 20% of patients just before the onset of the skin rash. lymphadenopathy is evident at least 24hr before the rash appears and may remain for 1 wk or more. the exanthem is more variable than that of rubeola. it begins on the face and spreads quickly. its evolution is so rapid that the rash may be fading on the face by the time it appears on the trunk. mild itching may occur, the eruption usually clears by the third day, and desquamation is minimal. in contrast to rubeola, there is no photophobia. the spleen is often slightly enlarged. especially in older girls and women, polyarthritis may occur with arthralgia, swelling, tenderness, and effusion but usually without any residuum. any joint may be involved, but the small joints of the hands are affected most frequently.
diagnosis
the diagnosis of rubella may be apparent from the clinical symptoms and physical examination, but it is usually confirmed by serology or virus culture.
treatment
there is no specific antiviral therapy treatment is entirely supportive.
post-exposure prophylaxis
for the susceptible pregnant woman exposed to rubella for whom abortion is not an option, immunoglobulin should be administered in a dose of 0.55ml/kg, which reduces the attack rate but does not eliminate the risk of fetal infection.