The sudden dieback is a sharply developing disease, allegedly virus etiology, occurs at children of younger age usually sporadic, but sometimes accepts character of epidemics. Its distinctive feature consists that in the beginning the body temperature which cannot be explained with anything and which in 3 — 4 days (is more rare than 1 — 5 days) also sharply decreases to normal sharply increases. At the same time there are rashes which are quickly turning pale and withering. Etiology. A certain evidence of the virus nature of a disease is obtained. Serum, a heparinized blood, washouts about the throats received for the 3rd day of a feverish state and in the 1st day of rashes can cause diseases in susceptible children, and also in monkeys. In typical cases the incubation interval at monkeys makes 4 — 5 days, and children have 9 — 10 days. All attempts to allocate the activator were unsuccessful. Serological tests are not developed, nature of pathological changes is not studied. Epidemiology. Degree of contageousness is unknown. The tendency to more frequent disease in spring and autumn months is noted. Boys and girls are equally susceptible. As it was noticed at not numerous epidemics, the incubation interval makes 7 — 17, but the thicket is 10 days old. The epidemiological model of an infection remained not clear. Sporadic cases at babies and rare epidemics among children of more senior age groups allow to suggest about local character of the infection affecting the vast majority of the population in the childhood and leaving durable immunity. Most often children at the age of 6 — 18 months get sick, 3 years sometimes are aged more senior. Cases of children of advanced age and even adults are described. Clinical manifestations. The beginning is sudden: sharply body temperature to 39,4 — 41,2 °C increases. At the same time or a bit later spasms can develop. The mucous membrane of a throat is a little inflamed, cold without any features develops. Lack of physical signs which would allow to explain fervescence draws attention. Despite it, the child feels usually quite well. The diagnosis can only be suspected by an exception of other possible infections which are followed by a feverish state at children of this age (average otitis, acute pyelonephritis, pneumonia, meningitis, pneumococcal bacteremia).
In the first 24 — 36 h after fervescence the number of leukocytes increases to 16 — 20-109/l, also the number of neutrophils increases. Next day and during 3 — the 4th day of an illness the number of leukocytes sharply decreases to 3 — 5-109/l. The absolute neutropenia with the relative lymphocytosis reaching sometimes 90% is noted. The number of monocytes can increase. The composition of cerebrospinal fluid does not change. Body temperature decreases critically for the 3rd or 4th day. Just before it or soon after its normalization spotty or pyatnistopapulezny rash on a trunk develops in the beginning, then extends to a neck and hands. On a face and legs of rash are insignificant or are absent. Rash seldom remains more than 24 h, quickly turns pale and disappears. The peeling is observed seldom, there is no pigmentation left. During rare epidemics the diagnosis of a disease can be suspected also in the absence of rash, but Clemens is not possible to confirm it. Observed enanty on a soft palate in the form of small erythematic specks and strips. Development of small periorbital hypostasis is described. In some cases lymph nodes on a neck increase, but they never reach the sizes noted at a rubella. Nevertheless increase in occipital lymph nodes can be also an auxiliary diagnostic character at differentiation of an acute dieback and pneumococcal bacteremia. Differential diagnosis. The greatest difficulties arise at differential diagnosis with a rubella from which the sudden dieback differs mainly in high temperature of a body in a prodromal stage. Measles and fever of the dengue, in addition to other clinical signs, differ in the fact that at them rash develops earlier, than body temperature increases. Temperature reaction is noted at measles in 3 — 4 days prior to rashes, and sharp and its substantial increase (to 39 — 40 °C) happens along with skin rashes. Besides, at measles body temperature keeps at the high level within 2 days. Lack of spots of Koplik, rhinitis, conjunctivitis and cough also helps to distinguish a sudden dieback from measles. Pneumococcal bacteremia can be followed by a feverish condition, lack of physical signs and a satisfactory general condition of the child. However the number of leukocytes is, as a rule, increased, and from blood pneumococci are sowed. The differential diagnosis with entero-and adenoviruses usually comes easy. Some allergic rashes, for example at treatment by penicillin, it is difficult to distinguish from a sudden dieback. The forecast is quite favorable, except for some cases when the disease is followed by extremely high temperature of a body and spasms proceeding for a long time. Prevention and treatment. Specific methods of prevention and treatment do not exist. The babies and children of younger age inclined to convulsions, it is recommended to treat sedatives. Antipyretics help to reduce body temperature and to reduce concern of the child.