From Big Medical Encyclopedia

INCUBATION INTERVAL (Latin incubatio incubation of baby birds; synonym: incubation, stage of latency) — the initial eclipse period of an infectious disease from the moment of implementation of the activator in a macroorganism before emergence of the first clinical signs of a disease.

Nominative is characteristic feature of infectious diseases.

In dynamics of Nominative it is possible to allocate three conditional phases: the phase of the beginning of Nominative which is matching the moment of infection or a little lagging behind it as a result of adaptation of the activator to a macroorganism; the phase of development of Nominative which is characterized by reproduction and accumulation of the activator in the adapted environment (primary center of defeat), its dissimination in the next cells, fabrics, bodies and priming subclinical response of an organism (hl. obr. immunological); the phase of end of Nominative which is characterized by further deepening patol, process in fabrics and bodies of a macroorganism frequent transition of dissimination to generalization with emergence at the end of a phase of the first portions of the activator in blood (lymph), urine.

From a macroorganism in the last phase there is a further mobilization of means of protection at the cellular and humoral levels, strengthening of oxidizing processes, disintegration of nitrogenous substances and a glycogenolysis; the infectious antigenemiya with gradation at the end of a phase in a toxaemia is shown or amplifies (an endotoxemia, an enterotoksemiya and so forth).

Dynamics of Nominative is not always so consecutive and natural. The current of Nominative can break on any of the given phases. So, quite often final phase can without emergence a wedge, signs to pass into the asymptomatic course of an infectious disease with a possible carriage (allocation) of the activator.

Such outcome, obviously, is the cornerstone also latent, hl. obr. virus (e.g., herpes, a rubella), and some bacterial infectious diseases (initially latent tuberculosis, syphilis, a brucellosis) with long experience of the activator in a macroorganism. It is well also known that only the small percent of the persons infected with tubercular bacteria gets sick further (apprx. 10%); in other cases of Nominative imperceptibly passes into a long latention.

In some cases the patient already in a phase of end of Nominative is dangerous in epidemiol, the relation since can be not recognizable source of contagiums. E.g., massive emergence of the causative agent of a viral hepatitis And in blood and excrements at the end of Nominative is established. At a viral hepatitis In the activator the wedge, symptoms of a disease collects in blood in 1 — 1,5 month prior to emergence, and on 7 — the 21st day after infection a disease can be revealed at 80% of the persons inspected by means of fermental methods.

Undergoes change in Nominative and the activator. So, L-forms of bacteria at a meningococcal infection, a typhoid appear, the activator loses or gets some new antigenic components, interacts with fabric components of the patient, and, thus, there are premises for early autoimmune processes.

At one infectious diseases (e.g., at skin type of a leushmaniosis, tetanus, rage) duration of Nominative fluctuates in considerable limits, at others it is rather constant (a typhoid, cholera, plague, flu, measles, etc.) * Fluctuations in duration of Nominative can be observed also at any separate infectious disease that is defined by many conditions: 1) quantity and character of the activator, factors of its pathogenicity, 2) a condition of protective forces of an organism (specific and individual), first of all cellular (T - and B-lymphocytes, macrophages) and humoral immunity, nonspecific mechanisms of protection, a condition of barriers, cellular membranes, eliminative organs; in the ways of receipt of the activator to a macroorganism; 3) the environmental factors exerting impact on a state micro and a macroorganism on emergence and a current both an infectious disease, and, naturally, Nominative.

Allocate more often the meeting Nominative (so-called «average» term of Nominative), and also minimum and maximum (tab.).

The shortest Nominative is usually observed at the infectious diseases proceeding as toxicoinfection (food toxicoinfections) at single-step massive infection, and also in cases when the activator or its toxins manage to reach the place of the appendix quickly. E.g., at tetanus of Nominative is shorter at wounds in the head, and also at the extensive smashed wounds when the activator and its toxins in a large number get to blood, and more for a long time at hit of the activator in the fabric poor in vessels. The phenomenon is insufficiently studied, a cut it is possible to characterize as a latent sporonositelstvo (at tetanus) when from the moment of the actual penetration the dispute in an organism before their turning into vegetative forms and, therefore, developing of a disease can take place vaguely long time.

On duration of Nominative at adults and children it is approximately identical, except for extreme age (at aged it is longer, and at newborns — is shorter). Active or passive immunization can lead to lengthening of Nominative.

The doctor in some cases the end of Nominative, i.e. emergence in the patient of the symptoms of an infectious disease found at laboratory tool and a wedge, inspection can be registered. The earlier the first symptoms of a disease will be fixed, the more effectively will be to lay down. - professional, actions both for this patient, and for the persons contacting to it throughout Nominative. It is obvious that further progress in klinikolaboratorny inspection of infectious patients, use adequate biol, models terms of Nominative at each patient taking into account his premorbidal status will allow to define more precisely (vaccination, a seroimmunity and so forth).

Knowledge of duration of Nominative at purpose of therapy is of great importance (to lay down. - professional, an immunotherapy of rage, tetanus, measles, botulism, diphtheria) and its terms for epidemiol, practicians: establishment of a source of an infection, determination of terms of a quarantine (see. Karantin, karantinization ) etc.

See also Infectious diseases , Infection .

An incubation interval at helminthoses

At an invasion of one helminths (trichinellas, opistorkhis, etc.) Nominative often decides on adequate accuracy, at others only approximately. Difficulties are substantially caused by complexity of early recognition of a number of helminthoses as a wedge, their manifestations are often observed earlier, than there is an opportunity to precisely confirm a disease by detection of eggs and larvae of helminths. So, the early acute phase of an opisthorchosis sometimes develops in 2 weeks after infection with this helminthosis, and eggs of helminth — a disease-producing factor appear in duodenal contents and Calais of the patient only in a month. Besides helminthoses quite often proceed at poorly expressed a wedge, the phenomena and even subclinically and is very difficult to catch the beginning of a disease.

The organism of the owner answers antigenic influence of helminths with cellular and humoral immune responses, thanking the Crimea sometimes parasites prematurely are allocated from an organism of the owner and even perish. These processes are especially expressed at fabric helminthoses and those intestinal helminthoses which larvae of activators migrate in a body of the person, napr, at ankilostomidoza (see), ascaridosis (see).

At some helminthoses symptoms of a disease arise directly at implementation of larvae in tissue of the person, napr, damages of skin at penetration of larvae into it ankilostomid, shistosy, strongiloides.

Table. Duration of an incubation interval at some infectious diseases (in the table duration of an incubation interval is specified in days; hours, months, years are specified in cases when, it makes a reservation) *

Bibliography: Baroyan O. V. and Porter D. R. International and national aspects of modern epidemiology and microbiology, page 192, M., 1975; B of lyu-@ of e r A. F. Viral hepatitis and its outcomes, page 38, Riga, 1970, bibliogr.; Zdrodovsky P. F. Problems of an infection, immunity and allergy, page 7, M., 1969, bibliogr.; Ioffe V. I. Clinical and epidemiological immunology, L., 1968, bibliogr.: The multivolume guide to microbiology, clinic and epidemiology of infectious diseases, under the editorship of H. N. Zhukova-Verezhnikov, t. 4, page 69, M., 1964; Pathological physiology, iod of an edition of A. D. Ado and L. M. Ishimova, page 100, L., 1973; The Guide to infectious diseases, under the editorship of A. F. Bilibin and G. P. Rudnev, page 29, M., 1962; Shuvalova T1\P. Infectious diseases, M., 1976.

I. V. Rubtsov; N. N. Plotnikov (helminth.).