Sporozoa

SPOROZOA (sporoviki), one of the classes of the type of simple animals (Protozoa). This includes parasitic protozoa that multiply by means of variously differentiated spores, often enclosed in resistant shells and serving for the distribution of the species and for the transmission of infection by sporozoans to other animals. Uninucleate or multinucleate vegetative individuals of S. usually lack organelles of movement and in various groups of this class, sometimes even those close to each other in systematic relationship (Monocystidea and Polycystidea), exhibit considerable morphological diversity. In some S., the cellular body is divided into 2-3 segments (Polycystidea) with adaptations on the first segment for attachment in the form of holdfasts, teeth, and hooks. Nutrition occurs by osmosis. A pulsating vacuole is absent. For many S., the alternation of generations is characteristic, and in some this is associated with a change of hosts. Due to the extensiveness of the class S., to determine the belonging of certain forms of parasites to it, besides ecological-biological features (type of host, nature of localization, nature of primary and secondary consequences of parasitism, etc.), asexual forms of reproduction or the structure of spores may serve. Typical representatives of S. are coccidia (see), gregarines (see), and some Haemosporidia (see). There is no unity of views among authors regarding cnidosporidia (see Cnidosporidia) and sarcosporidia (see Sarcosporidia); some include these groups in the class, while others single them out as independent classes. In the developmental cycle of the host-infecting individual, the sporozoite, which after penetrating into the host cell rounds up and by asexual reproduction (schizogony) gives rise, passing through the schizont stage, to a more or less numerous cellular elements-merozoites, which after exit penetrate into new cells and serve for distribution in the body of this particular host. The asexual developmental cycle repeats in this manner an indefinite number of times, as a result of which numerous host cells are affected, or the sporozoite after penetration into the body and a period of growth directly transforms into gametocytes. The period of reproduction by schizogony is replaced by the formation of gamete forms. Male and female gametes, developing after reduction of the nuclear apparatus, following pairwise fusion (anisogamous or isogamous copulation) give rise to a zygote or ookinete, if the product of copulation possesses a certain degree of motility. The zygote is surrounded by a resistant shell and receives the name oocyst, divides into several separate elements-sporoblasts, which encyst and transform into sporocysts. Sporoblasts by asexual reproduction-sporogonia-give rise to sporozoites. In the process of formation of sporoblasts and sporozoites in the maternal oocyst and sporocysts, the so-called residual bodies (Restkörper, residual body) arise, representing parts of protoplasm unused in reproduction. The oocyst, surrounded by a dense shell resistant to unfavorable influences, after entering the external environment serves as a source of infection for new animals. In gregarines, sporozoites are formed directly from the zygote after its encystment. In some S., spore formation occurs at the end of the life cycle (coccidia, gregarines, haemosporidia), in others this process is observed throughout the period of existence of vegetative individuals (cnidosporidia). In the latter, spores develop endogenously after the isolation in the multinucleate vegetative cell around certain nuclei of protoplasm (pan-sporoblasts). The final development of spores is associated with pedogamous or autogamous fertilization. The life cycle of S., with the alternation of asexual and sexual generations, proceeds either in the body of one host, and in this case infection of susceptible animals is carried out through the external environment, for example, when consuming food contaminated with spores, or the sexual process, accompanied by the formation of infecting forms, occurs in the body of another host (Proteosoma and others), which plays the role of a vector of invasion (insects, ticks). In such cases, resistant shells of spores are absent. For a considerable number of species, the details of development in the invertebrate animal are little studied (haemosporidia).-S. as intracellular and cavity parasites are widely distributed among various groups of vertebrates and invertebrates (tunicates, arthropods, mollusks, worms) animals and cause various diseases (malaria of humans and birds, piroplasmoses, coccidioses, fish diseases, nosematosis of bees, etc.). Due to the uncertainty of phylogenetic relationships between individual groups of S., the classification of this class is not firmly established. Lit.-see lit. k st. Protozoology.

A. Marcoin. SPOROTRICHOSIS (Sporotrichosis), syn. disease de-Beurmann (de Beurmann), a relatively rare fungal disease of humans, affecting mainly the skin and subcutaneous tissue. S. was first described by Schenk (1898), the question was thoroughly developed by de Beurmann and Gougerot. A total of about 350 cases of S have been described; in the USSR it is observed extremely rarely. Many varieties of sporotrichon have been described. Sporotrichon is a thread-like spore-bearing fungus with septate, uniformly thick branched threads; spores of the same size, ovoid or spherical. Clinically, 4 types of S are distinguished: 1) disseminated gummatous, 2) localized subcutaneous or cutaneous, 3) superficial S of the skin, 4) extracutaneous S. In the group of disseminated gummatous S, 4 forms are in turn distinguished: a) gummatous non-ulcerated, b) ulcerated, c) mixed, d) form with large abscesses [(Abscessus sporotrichoticus multiplex Dor (Dor)]. In the ulcerated form, ulcers can very much resemble syphilitic gummas (syphilitic form), tuberculous ulcers (tuberculoid form), ecthyma (ecthyma-like form) and others. In the mixed form, in addition to non-softened, fluctuating and ulcerated nodules, secondary gummatous lymphangitis (lymphangitis gummosa sporotrichotica) and various skin and epidermal rashes are found; sometimes rashes are simultaneously present on the mucous membranes, lesions of bones, muscles and others. Localized S.-so-called sporotrichotic chancre--develops mostly in places of skin damage, more often on the fingers of the hands and wrists: a dense yellowish-brown, crusted tumor or superficial ulcer, mostly there is lymphangitis. Superficial cutaneous S. can resemble ringworm, eczema, impetigo and others. S. can affect the nails, mucous membranes (mainly of the pharynx and respiratory tract), eyes, muscles, tendons, joints, bones and internal organs (more often lungs, liver and testicles). S. of bones can be primary and secondary, its clinic is diverse: processes of compaction and suppuration in the periosteum can be combined with osteomyelitis, spontaneous fractures are also observed. Path-anatomically, a typical sporotrichoma consists of 3 zones: a central microabscess, a middle zone, "characterized by the predominance among numerous giant and plasma cells of acidophilic epithelioid cells, and an outer fibroplastic zone, penetrated by lymphocytic-plasma cell infiltrate. Sporotrichons can be found on plants, bushes and trees, on grass, hay, straw, on cereal grains and flour dust, in earth and street dust, on food products, on animals and others. Animals, mainly rats, can be carriers of the fungus to humans. Sporotrichons can also saprophytize on human skin. There are two possible ways for sporotrichons to penetrate the body: 1) the fungus enters an existing skin or mucous membrane damage; a primary lesion forms, leading then to lymphangitis and new foci; 2) the fungus, entering the body with food, water or dust, is spread hematogenously--a disseminated form of sporotrichosis develops. Foerster considers S. as a professional disease of people engaged in agriculture, gardening and horticulture. S. indeed more often affects the rural population. The polymorphic symptomatology of S. and the frequent significant clinical similarity with tbc, syphilis, Gilchrist's blastomycosis and chronic pyoderma are almost always the cause of fluctuations in the diagnosis of S. The following helps in correct recognition: multiplicity of foci, frequent localization on the upper extremities, painless lymphangitis, absence of a tendency to spontaneous ulceration, opening of nodes by several small fistulous openings, absence in the contents of abscesses of a core and curdled masses, dark-violet color of rashes; after healing of ulcers, small, irregularly shaped scars with jagged and pigmented edges remain. To confirm the diagnosis, one should always strive to isolate cultures of the fungus (bacterioscopically in pus it is rarely possible to detect elements of the fungus) and obtain positive allergic skin and subcutaneous reactions with sterilized dilutions of the fungus, as well as the agglutination reaction of spores with the blood serum of the patient. Positive results of experiments on animals have less diagnostic significance. With early diagnosis and treatment, the prognosis is favorable even in the disseminated form; it is significantly worse if the mucous membranes, internal organs or bones are involved in the process, as well as in cases of poor tolerance to iodine and in cases when the disease has taken on a septic character. In the vast majority of cases, S. is a benign disease, healing in 1-3 months. The almost certain method of treatment is the use of iodine preparations, preferably KI, necessarily in gradually increasing doses (from 2.0 to 6.0 or more per day). To avoid relapses, treatment should be continued for another month after clinical recovery. Locally for closed foci-resorptive agents (heat, ichthyol compresses, etc.); surgical intervention is not recommended; for ulcers-compresses with Lugol's solution, ointments with iodine preparations. In warty forms of S, as well as in cases resistant to iodine, radiotherapy can be applied.