Fifth Disease

FIFTH DISEASE, an acute infectious disease of predominantly childhood, characterized by a spotted-papular rash and almost complete absence of general symptoms; in its development, the rash produces an extremely variable, diverse picture, forming rings, garlands, and other figures, which is considered particularly typical for this disease. The name "fifth" is given to this disease because it is considered an independent disease along with the four known exanthematous diseases of childhood: scarlet fever, measles, rubella, and so-called fourth disease (Filatov-Duke disease). Other names also exist: erythema infectiosum, exanthema variabile, megalerythma epid., localized rubella, etc. In Germany and Austria, the most common name is erythema inf., while in France and Italy it is fifth disease, as well as megalerytheme epidemicum. History. Fifth disease was first described by Tschamer in 1889 under the name "localized rubella" (epidemic in Graz). This was followed by reports from Austria and Germany by Gumplowicz, Pospischill, Sticker, and others. In 1915, Tobler described a large epidemic (66 cases) in Breslau. From other countries, there are brief reports of individual cases and small epidemics. In the USSR, fifth disease is little known and almost unstudied. In 1927, the first two works in Russian appeared: by V. I. Molchanov (Moscow) and L. O. Finkel'shtein (Kiev). Epidemiology. F. D. occurs either as individual cases or in the form of household epidemics, which sometimes take on widespread distribution. According to observations by some authors (Tobler and others), the disease is transmitted directly from sick to healthy individuals, while others doubt its contagiousness. It is most often observed in early spring. The disease primarily affects preschool and school-age children; it is rarely found among infants and adults. The causative agent is unknown. The incubation period is from 7 to 17 days. Clinical. Prodromal phenomena are usually absent. In rare cases, rhinitis, photophobia, and general lethargy and weakness were observed as initial symptoms. In the vast majority of cases, the rash is the first and only symptom of the disease. The localization of the rash is characteristic. It mainly affects the face; there is less of it on the trunk and it is expressed more weakly. The rash first appears on the cheeks in the form of individual spots, which quickly merge with each other, making the cheeks bright red, as if glowing; the lips, chin, and cartilaginous part of the nose remain free of rash, resulting in the impression of a scarlet fever triangle, but on the bridge of the nose there is a rash in the form of a narrow strip that directly transitions into the erythema of the cheeks; the unique facial picture obtained due to this distribution of rash, authors compare with a "butterfly". Itching usually does not occur. Simultaneously or soon after appearing on the face, the rash appears on the extensor surfaces of the limbs. Here it also consists at first of individual small spots, which, gradually increasing, reach the size of a 20-kopeck coin or larger. In their further development, the spots may merge, forming large fields of irregular shape and leaving intervals of normal skin. But especially characteristic for F. D. are the pictures obtained during the reverse development of the rash. This reverse development begins in the central parts of the spots; the color of these parts gradually changes from red to purple, bluish, and yellow-brown, while the periphery of the spots retains a bright red color; as a result of this transformation, figures of rings, garlands, etc. are obtained. On the cheeks, after the disappearance of these figures, a cyanotic tint and even swelling may persist for a long time. The rash lasts on average 8-10 days. In mild cases, it disappears already after 3-4 days, but sometimes it drags on for up to 3 weeks. It does not leave scaling behind it. As varieties of the rash, measles-like and scarlet fever-like forms are described. The measles-like form occurs when individual spots do not merge and disappear without undergoing the mentioned transformation. It is usually observed in small children. The scarlet fever-like form occurs when spots merge, forming diffuse erythema without intervals of normal skin. The general condition remains good. The temperature is either normal or rises moderately and for a short time. From the blood side, in the first days, a normal number of leukocytes or even leukopenia is observed, which is later replaced by a slight leukocytosis; simultaneously, eosinophilia may occur. Complications usually¹ do not occur. Recognition, if the disease appears epidemically and runs in a typical form, presents no difficulties. In individual cases, it can first be confused with scarlet fever. Indeed, the existence of a triangle on the face and diffuse erythema on the trunk in the first 2-3 days gives F. D. considerable similarity to scarlet fever, however, the absence of angina, raspberry tongue, the predominant localization of the rash on the extensor surfaces of the limbs, and most importantly, the appearance of figures in the further development of the rash allow one to confidently exclude scarlet fever. In small children, with a measles-like character of the rash, it is not easy to distinguish F. D. from measles. The absence of a prodromal period, Filatov-Koplik spots, and catarrhs of the respiratory tract helps in making the correct diagnosis. From rubella, besides localization and greater brightness of the rash, F. D. is also distinguished by the absence of swelling of the occipital glands. It is most difficult to distinguish F. D. from polymorphous exudative erythema (eryt. ex-sud. multif. Hebrae) because in both conditions, polymorphism of the rash and the appearance of various figures are observed. In differential diagnosis, it must be borne in mind that exudative polymorphous erythema is rarely found in children, it lacks the bright redness of the cheeks, it occurs not epidemically but as individual cases, and is accompanied by high temperature, pains in the limbs, and significant disturbance of the general condition. The prognosis is completely favorable. No treatment is required. What does F. D. represent in a nosological relationship? Tschamer and Tobler, who first described F. D., considered it an atypical form of rubella. Despite this, in the German literature in recent years, the view has apparently become firmly established that it is an independent disease that must be distinguished not only from measles and scarlet fever, but also from rubella, mainly on the grounds that having had rubella does not protect against F. D. and vice versa. However, the question of the independence of F. D. cannot be considered finally resolved (Teissier). Even today, one has to observe epidemics of rubella during which the rash in individual cases cannot be distinguished from the rash in fifth disease (V. Molchanov).