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The influence of environmental factors on the development and survival of eggs and larvae of helminths


Oxygen. It has been established that about 0.0009 cm3 of oxygen is required for the development of Ascafis suilla eggs. Mature A.suilla eggs need less oxygen than developing eggs. Each egg in the process of development requires 0.0000025-0.0000031 cm3 of oxygen. With the cessation of oxygen access, the further development of helminth eggs stops and can continue during aeration.
The survival rate of roundworm eggs in ponds depends on the amount of dissolved oxygen. When the oxygen content in water bodies is within 3-5 mg / l, ascaris eggs in most cases die after 3-4 months, and in the presence of 8-10 mg / l they survive up to 1 year. If there is 1.3-1.8 cm3 (1.9-2.6 mg / l) of oxygen in water and a temperature of 23 ° C, the development of ascaris eggs slows down by 30%; at the same temperature, but with a content of 1.1 cm3 (1.6 mg / l) of oxygen - by 50%. At a water temperature of 30 ° C and an oxygen content of 1.8 = 3 cm3 (2.6-4.3 mg / l), the development of ascaris eggs occurs normally, but the oxygen content drops to 0.9-1.3 cm3 (1 , 3-1.9 mg / l) slows down their development by 30-50%. An increase in the dissolved oxygen content to 21 cm3 / L (33.6 mg / L) causes the death of Ascaris eggs at all stages of embryonic development. Whipworm eggs in an oxygen-free environment at a temperature of 30 ° C die after 20 days, and at a lower temperature they remain viable (not stirring), up to 2-3 months. Hookah eggs in an oxygen-free environment die within 1-3 months, and their larvae, like pinworms, do not develop in the absence of oxygen.
Temperature. The temperature of the soil, at which the development of ascaris eggs is possible, is from 7-8 to 36-37 ° C. As for the lower threshold temperature of the soil, at which the development of ascaris eggs begins, the information on these issues is contradictory. So, some authors argue that ascaris eggs begin to develop at a soil temperature of 7–8 ° C, others believe that at a temperature of 10.1-10.3 ° C, while others believe that at 13 ° C. This diversity, apparently, can be explained by the fact that experimental studies were carried out in different soil and climatic conditions (in the North, in the Central and Southern regions of the country), to which, possibly, Ascaris eggs adapted.
The temperature factor determines the rate of development of the embryo in the egg. So, at a temperature of 12–15 ° С, ascaris eggs develop within 40–45 days, at 20 ° С –– 20 days, at 22 ° С –– 16 days, at 24 ° С –– 14 days, at 26 ° С – 11, 5 days, at 30 ° C - 9 days. To complete the development of ascaris eggs at a temperature of 17-30 ° C to the stage of a mobile larva, 180-200, and to the invasive stage 297-309 ° of effective heat, are needed. The optimum soil temperature at which whipworm eggs develop to the larval stage is 30 ° C. At this temperature, the development of eggs is completed in 17.5 days, at 25 ° C in 29 days, at 20 ° C in 57 days, at 15 ° C in 120 days. When the soil temperature is above the optimum, the egg development time is shortened, but at the same time, some of the eggs of the whipworm die. For example, at a temperature of 35 ° C, the development of eggs is completed in 11 days, but about 50% of them die. Ankylostomid eggs develop at a soil temperature of 16–28 ° C in 5–12 days. The maximum of larvae in them appears at a temperature of 22–32 ° С.
Higher and lower in comparison with the indicated temperatures have a detrimental effect on helminth eggs. Ascaris eggs at a temperature of 45–55 ° C die within a few minutes (up to 1 hour). Dried eggs die faster than those in water; when immersed in hot water, Ascaris eggs die at a temperature of 70 ° C in 1-10 s, at 60-65 ° C in 20 s, at 50–55 ° C in 5-10 minutes.
Eggs of A.lumbricoides are more resistant to low temperatures than eggs of other geohelminthes. Mature A.lumbricoides eggs are less resistant to low temperatures than immature ones. It is indicated that prolonged freezing of non-segmented and mature eggs at a temperature of -1-5 ° C does not affect their viability, while lower temperatures (-12-45 ° C) for 3 months somewhat delay the rate of subsequent transformation of immature eggs; eggs at later stages of development, under the same conditions, almost all die, and those remaining alive very slowly complete the transition to the larval stage. When the temperature drops to -20—27 ° C, ascaris eggs with larvae die after 20 days, and immature eggs do not die even after 40 days; at a temperature of -30 ° C, ascaris eggs disappear after 24 hours.
Multiple change (20-30 times) of temperature contributes to the destruction of ascaris eggs. Whipworm eggs immersed in hot water at a temperature of 70 ° C die after 1 s, at 60 ° C after 2 s, at 59 ° C after 10 s, at 55 ° C after 3 minutes, at 45 ° C after 60 minutes They can tolerate a temperature of 0 ° C for 20 days, and at -3 ° C after 99 days they die 90%, at -12 ° C the death of Ascaris eggs occurs within 24 hours. Pinworm eggs disappear within a few seconds at a temperature of 55 ° C and above, and when it drops to -3-5 ° C - after 3 weeks; at -4–13 ° C - after 7 days, at -15 ° C -: after 5 days.
Humidity. Under natural conditions, roundworm eggs can develop at a relative soil moisture of at least 5–8%, whipworm - at 6–13%. For whipworm eggs, the relative humidity of 100% is optimal; at a humidity of 84.8% and below, they die in the laboratory. At a temperature of 25-27 ° C and absolute humidity of 11.8-23.4%, whipworm eggs disappear after 2 days.
Hookworm eggs are quickly destroyed when dried. For pinworm eggs, the relative humidity is 90-100%. They die after 8 days if the humidity drops to 68–80%; Indoors at room temperature they survive up to 35 days.
Solar radiation. It has been established that under natural conditions, the sun's rays significantly accelerate the death of Ascaris eggs. So, at a temperature of 56 ° C and a humidity of 23%, ascaris eggs in the feces die from the action of solar radiation after 2 days, while those excreted from the feces die in 5 minutes. It is reported that the death of Ascaris eggs does not depend on the duration of UV irradiation, but on its intensity. It was shown that solar radiation in 1-3 biodoses has a weak effect on the survival of pigmented ascaris and whipworm eggs, which are at different stages of development. It has been established that Ascaris eggs maintain viability until the start of segmentation at an illumination intensity of 18–19 biodoses, in the morula stage, 20–21 biodoses, in the blastula stage, with 22–23 biodoses, in the larval stage, with 26–27 biodoses and in the stage of a mobile larva - when exposed to 28-29 biodoses [Romanenko N.A., 1982].
Whipworm eggs are more stable: they lose viability before pigmentation begins when the intensity of illumination is 24–25 biodoses, in stage 2 of the blastomeres when exposed to 28–29 biodoses, in the stage of an oval and cylindrical embryo when exposed to 30–31 biodoses. Only single eggs of whipworms in the stage of motile larva remain alive at an intensity of illumination of 31 biodoses. It was established that for the development of an ascaris egg at the stage of an unsegmented embryo to the stage of two blastomeres, 34.2 degree days are needed, up to the stage of 8 blastomeres - 50.8, to the stage of 16 blastomeres - 69.4, to the early morula - 79, to the late morula - 100.4, to gastrula - 119.4, to the tadpole larva - 300 degree-days of effective heat. The death of ascaris eggs and an almost practical release from them is observed at 3388 degree days of effective heat.
The development and survival of helminth eggs in the environment is influenced by the season, the depth of their entry into the soil, the mechanical and chemical composition of the latter, the temperature of the air, soil and its moisture.
In moist sandy and sandy loamy soils, geohelmintic eggs develop better than in clay and loamy soils. In dry periods of the year, ascaris eggs die in the shortest time and in a small amount on the surface and at shallow depths (up to 3 cm) of sandy, sandy soils, and primarily in areas exposed to direct sunlight.
Salinity of the soil with salts of sodium, potassium, chlorides, sulfates prevents the development of invasive larvae with hookworms. The acid reaction of the medium also contributes to this. We did not establish the detrimental effect of a sharp change in the environment (from neutral to alkaline, from neutral to acid, from acid to alkaline and vice versa) on the viability of ascaris and whipworm eggs [Romanenko N.A., 1982; Romanenko N.A. et al., 1990].
The effect of ultrasound on eggs with helminths. The effect of ultrasound on helminth eggs is based on its large penetrating ability and is determined by mechanical, thermal and chemical effects, depending on the dosage and frequency of the emitter. It is indicated that ultrasound with a frequency of 1–2 MHz and a power of 1–2 W for 3-5 s has a stimulating effect on the development of eggs of strongilates, but after 10-15 s it causes destruction of the structure of the egg contents. The action of ultrasound for 20-60 s causes complete destruction of the egg structure at all stages of development. It was found that 9 days after exposure to ultrasound for 30 s - 4 minutes, human roundworm eggs develop only in 17–38.3% of cases, and when exposed to ultrasound for 8–32 minutes, only in 2.8–7% of cases. After 3.5 months, all ascaris eggs die.
It was shown that under the influence of ultrasound, Ascaris eggs are 1 day ahead of control cultures in their development. It is also noted that human roundworm eggs complete development 1 day earlier than pig roundworm eggs. In eggs of human roundworms, under the influence of ultrasound, an exit of the larvae from the shell is observed for 3 min. 1 week after exposure to ultrasound, the death of mature eggs of both types of roundworm occurs.
The effect of ultrasound on the plerocercoids of the broad ribbon, the larvae of trichinella and miracidia fasciola was noted.
The effect of ionizing radiation on eggs and larvae of helminths. Helminth eggs have a high degree of radiosensitivity, resulting in a slowdown in their development, morphological changes in larvae of various ages. The degree of delay in egg development depends on the dose of radiation. It has been shown that at a dose of 40 000 to 45 000 Gr R-rays, all ascaris eggs irradiated at the zygote stage die. At an irradiation dose of 30,000–40,000 Gy, single eggs developed to the larval stage. Doses of 15,000–25,000 Gy drastically slowed down the development of eggs. When eggs are irradiated with a dose of 2000-5000 Gy, their development does not differ as a percentage of control. Some authors believe that the lethal dose for ascaris eggs located at all stages of embryogenesis is 60,000-120,000 Gy. Ascaris eggs at the stage of 8-16 blastomeres, morula, blastula, and early gastrula possess the highest radiosensitivity.
The high sensitivity of trichinella larvae to the action of ionizing radiation has allowed American scientists to recommend it for sterilization of pork affected by trichinosis. When meat was irradiated with gamma rays in doses from 500 to 23,000 Gy (15 Gy / min), its complete sterilization from trichinella occurred at an irradiation dose of 800 Gy.
There is evidence that the development of fasciol sharply slows down even at doses of 3000 and 8000 Gy, while the developed metacercariae amounted to no more than 0.4%, with a radiation dose of 12,000 Gy they did not develop at all. At an irradiation dose of 30,000 Gy, morphological changes in cysticercoid dwarf tapeworms are observed; exposure to 10,000 and 20,000 Gy inhibits the postembryonic development of C. bovis and C. pisiformis. When irradiated with S. mansoni cercariae at a dose of 3500 Gy, adult parasites do not develop.
It has been shown that when gamma rays “Co and l37Cs are used, ascaris, whipworm, and broad tapeworm eggs in household wastewater have different radiosensitivity. Ascaris eggs have the highest radio resistance, then whipworm eggs, broad tape.
The viability of ascaris eggs is completely suppressed by doses of 46,500 Gy, whipworm - 37,200 Gy, wide tape - 4650 Gy. The invasive ability of larvae that developed in irradiated ascaris eggs at irradiation doses of 9300–18 600 Gy is markedly reduced in comparison with the control. At high doses, the invasive ability of the larvae is completely suppressed.
Synthetic detergents (syntanol DS-10, sulfanol NP-1, alfapol-9 and ABC) do not significantly affect the viability of ascaris, whipworms, and broad tapeworms, but reduce the invasive ability of ascaris larvae developed in irradiated eggs, even compared to that of larvae transforming in eggs irradiated in waste water. The possibility of using ionizing radiation for deworming of liquid manure is currently being studied.
The effect of certain biological factors on helminth eggs and larvae. Helminth eggs, being in the environment, are exposed to the destructive action of various types of bacteria, protozoa, insect larvae, worms, beetles, plants. Some strains of fungi, actinomycetes and bacteria isolated from the soil of vegetable gardens and irrigation fields have ovistatic and ovicidal effects.
A number of cultures of algae destroys embryos of ascaris eggs at different stages of development. Algae are most active in the spring and summer, when their destructive effect on ascaris eggs is manifested within 2.5 months. Soil algae have a stronger effect on roundworm eggs than algae from a pond.
The influence of the root system and rhizosphere of fodder beets, alfalfa, vetch, corn, wheat, timothy, barley, oats, clover, peas, sweet clover, lupine, marigold, calendula, chamomile, buckwheat, millet, ryegrass on the vitality of helminth eggs [Dimidova J. JL, 1980]. It was shown that the root system and rhizosphere of most plants do not significantly affect them. Barley, oats, peas, marigolds, calendula, which have the most developed fibrous root system, have a pronounced ovicidal effect. In dead eggs, a slight deformation of the embryo and some enlightenment of the shell were noticed. These signs indicate a negative effect of the root system on helminth eggs for a long period; changes in the egg develop slowly.
The rhizosphere of plants such as peas, marigolds, barley, calendula, oats, vetch, in the first half of their growth, to one degree or another stimulate, and in the second - delay the development of helminth eggs. Peas, oats and vetch stop their development much earlier than other crops. After this, a slow death of the embryo occurs. The action of the wiki is limited only by the delay in the development of eggs.
It has been established that helminth eggs can enter the intestinal tract of ciliary worms and larvae of droplets along with food. Passing through the intestines of ciliary worms, ascaris eggs and broad tapeworms remain viable, while in the intestines of droplet larvae they are destroyed. It was also shown that: 1) the larvae of some beetles do not swallow ascaris eggs; 2) the larvae of dragonflies, caddis flies and chironomids Pelopia villipennis eat helminth eggs without affecting their viability; 3) mosquito larvae and chironomids Glyptotendi pes polytomis, Camptochironomus tentans, Limnochironomys sp. and microtedipes from the chloris group destroy tapeworm eggs without affecting the survival of roundworm eggs;
4) the larvae of the Cloen dipterum, Heptagenia fuscogrisea, Siphlonurus aestivalis, as well as the chironomid Cricotopus from the Siivestris group destroy the tapeworm eggs and ascaris eggs. It is reported that some Canton beetles destroy ascaris eggs as a result of the direct effect of mandibles with a characteristic structure. It has been established that mites of the Macrochelidae and Parasitidae families eat and completely destroy, and small soil oligochaetes of the Enehytraeidae family swallow ascaris eggs. We found that in the dispersal of T.saginatus eggs on pastures, skin-eating beetles, skin-beetle larvae, ground beetles, carnivores, grave diggers can actively participate. It has been experimentally proven that the oncospheres of T.saginatus transit through the digestive tract of these insects and excrete with excrement without losing their viability. This fact can be explained by the digestive characteristics of insects. It is known that for the liberation of the oncospheres from the embryophore (shells), a consistent exposure to an acidic and alkaline medium of a certain concentration is necessary. Beetles do not have a stomach per se. The food lingers in the expansion of the anterior intestine, called goiter or proventriculus, the pH here is slightly acidic - 5.2. In the middle intestine, where the main processes of digestion take place, in ground beetles the pH is also slightly acidic - 5.9 = 6.0, and in beetles of the genus Dermestes, on the contrary, the pH is very alkaline - 9.6-10.2.
Thus, in beetles there is no consistent effect on the oncospheres of an acidic and alkaline medium of a certain concentration, moreover, the short duration of exposure (food takes 8-10 hours) and a small amount of digestive juices do not provide destruction of the embryophore or digestion of the oncospheres. Insects are mechanical carriers of invasive material. In this case, the possibility of infection of cattle increases many times: the oncospheres of T.saginatus are pulled apart by bugs for many meters from the place of excrement of feces, and during the flights of beetles - to longer distances; infected beetles can get to cattle with grass and hay.
In the literature there is information about the transit passage of invasive larvae of Trichinella through the digestive tract of ground beetles. On the contrary, such animals (coprophages) as pigs, dogs, and rats do not play any role in the epizootology of cysticercosis in cattle. It was experimentally established that the development of the oncospheres does not occur in the intestines of these animals, and their excretion with feces is also not observed. 7-10 hours after ingestion of T.saginatus eggs, they are digested in the intestines of animals.
In conclusion, it should be noted that the study of the influence of biological factors on the viability of helminth eggs in soil has not yet attracted the attention of researchers. Проведенные исследования носят поисковый характер, результаты их еще далеки от выхода в практику, однако представляют определенную научно-теоретическую ценность. Предположения, что яйца гельминтов могут подвергаться губительному действию со стороны почвенной флоры и фауны, находят все больше конкретных подтверждений в условиях эксперимента. Выявлен ряд организмов, вызывающих гибель яиц гельминтов; не подлежит сомнению перспективность работ по выявлению естественных врагов яиц гельминтов.
Устойчивость яиц и личинок гельминтов к химическим веществам. Этот вопрос изучали многие отечественные и зарубежные исследователи. В серии технических докладов ВОЗ (1985) суммируется опыт изыскания овицидов (химических веществ, губительно действующих на яйца гельминтов) в целях борьбы с гельминтозами. Было опробовано большое количество различных соединений. Из них овицидными свойствами обладали: цианистый калий, хлорид олова, различные соединения йода, четыреххлористый углерод, фенол, лизол, хлороформ, концентрированные спирты, серный эфир, ацетон, сероуглерод, изохлортион, хлортион, пентахлорфенол.
В последние годы выявлен еще ряд химических веществ (карбатион, тиозон, безводный аммиак, дазомет, поликарбацин, прометрин, цинеб, абгазная кислота, кубовые остатки хлора, полидим, ДП-2 и др.), губительно действующих на яйца и личинки гельминтов [Романенко Н.А., 1982].
Механизм действия овицидов, относящихся к разным химическим группам и обладающих различными физико-химическими свойствами, изучен недостаточно. Установлено, что значительная устойчивость яиц гельминтов к воздействию химических факторов объясняется наличием в их скорлупе полупроницаемой оболочки липоидной природы, которая пропускает только вещества, растворяющие липоиды или растворяющиеся в них. В связи с этим овициды по механизму действия можно подразделить на 2 группы: первая включает представителей, овицидное действие которых связано с разрушением всех оболочек скорлупы (карболовая кислота, бензилхлорфенол и др.); вторая — представителей, которые разрушают оболочки внешней половины скорлупы и растворяют липопротеиновые и липоидные компоненты оболочек ее внутренней половины (едкий натр, фэнэвак и др.).
Степень овицидного эффекта химических веществ зависит от дозы, структуры и физико-химических свойств обрабатываемого материала, глубины нахождения яиц, температуры, экспозиции и способа обработки. Например, тиозон (200 г/кг), внесенный в почву, покрытую пленкой (повышенная температура), при экспозиции 10 сут вызывает гибель яиц аскариды свиней в поверхностном слое на глубине до 2 см в 100 % случаев, на глубине 5 см — в 88,6 % случаев, на глубине 10 см — в 87,8 % случаев, а в почве, не покрытой пленкой, — в 48,2; 54,1; 59,7 % случаев соответственно. Гибель всех яиц гельминтов в твердой фракции жидкого навоза этот препарат вызывает при дозе 10 г/кг, в обычном свином навозе — при дозе 20 г/кг, в курином помете — при внесении 25—30 г/кг. При добавлении в фекалии аммиачной воды, содержащей до 2,5 % аммиака, через 5 ч погибают до 4 %, через 1 сут — 32 %, через 5 сут — 96— 98 %, через 20 сут — 100 % яиц гельминтов.


Наиболее полная овицидная активность препаратов проявляется при их контакте с отмытыми яйцами гельминтов и при температуре 18—24 °С, а в некоторых случаях практически не отмечается при воздействии тех же химических веществ на яйца гельминтов, находящиеся в фекалиях, осадке сточных вод, почве. Например, 3 % раствор карбатиона при его контакте с отмытыми яйцами аскарид обусловливает их гибель на любой стадии эмбриогенеза в течение 30 мин, тогда как гибель яиц аскарид, находящихся в фекалиях, наступает только через 2 нед и только после обработки 8 % раствором препарата. Перемешивание карбатиона с фекалиями более эффективно, чем обработка их с поверхности.
Овицидная активность аммиачной воды наиболее полно проявляется при температуре 18—24 °С и совсем отсутствует при 4—6 °С и ниже.
Особого внимания заслуживает препарат «Бингсти», полученный из проростков картофеля [Гримайло JI.B. и др., 1996]. Сравнение значений показателей гибели яиц аскариды в различных разведениях препарата при разных экспозициях выявляет закономерность: активность препарата возрастает в течение 8 ч, при дальнейшем увеличении экспозиции активность меняется незначительно.
При более высоком содержании препарата в чистой культуре и в сточных водах (разведение 10 7—104) наблюдается маловыраженное овицидное действие по сравнению с показателями активности в разведении 10 7—10 9 в чистой культуре; 10 7—10 в неочищенных сточных водах и 10 5—10 9 в очищенных стоках.
Использование нетоксичного препарата растительного происхождения, оказывающего специфическое действие на возбудителей гельминтозов в миллионных и миллиардных разведениях и вызывающих их гибель, позволит успешно решать вопросы обеззараживания различных объектов окружающей среды [Хроменкова Е.П. и др., 1997].
Способы применения овицидов зависят от их агрегатного состояния и характера обрабатываемых объектов. Например, газообразованные овициды (безводный аммиак) используются для обеззараживания нечистот, осадков сточных вод, навоза только в закрытых емкостях; порошкообразные (тиозон) и жидкие (растворы фенола, карбатиона, тиозона и др.) овициды наносятся на поверхности твердых объектов (пол, стены, почва) или перемешиваются с обрабатываемым субстратом (нечистоты, осадок сточных вод, навоз и др.) в барабанных смесителях.
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Влияние факторов окружающей среды на развитие и выживаемость яиц и личинок гельминтов

  1. Методы экспериментального изучения сроков развития и выживаемости яиц гельминтов в окружающей среде
    При изучении сроков развития и выживаемости яиц гельминтов требуется проведение специальных экспериментов с искусственной закладкой проб на различных объектах окружающей среды. Опыты необходимо проводить, с одной стороны, в условиях, наиболее приближающихся к естественным, а с другой — при которых пробы с яйцами гельминтов сохранялись бы в окружающей среде и их легко было бы извлекать для
  2. Методы определения жизнеспособности яиц и личинок гельминтов
    При обнаружении яиц гельминтов на различных объектах окружающей среды (почва, вода, овощи и др.) всегда необходимо определять их жизнеспособность по внешнему виду, окрашиванием витальными красками, культивированием в оптимальных условиях и постановкой биологической пробы, т.е. скармливанием лабораторным животным. Определение жизнеспособности яиц или личинок гельминтов по внешнему виду. Eggs
  3. Общая морфологическая характеристика яиц и личинок гельминтов
    Поскольку яйца и личинки большинства гельминтов выделяются через кишечник, то на практике чаще пользуются гельминтокопроскопическими методами исследований. При этом учитывают, что в пробах фекалий кроме яиц и личинок гельминтов встречаются споры грибов, крахмальные зерна, растительные клетки и волоски, ооцисты эймерий, цисты балантидий и другие структуры, иногда напоминающие яйца и личинки
  4. Частная морфологическая характеристика яиц и личинок гельминтов
    Частная морфологическая характеристика яиц и личинок гельминтов, присущих хозяевам определенных видов, приведена в подписях под иллюстрациями. МИКРОМЕТРИЯ ЯИЦ И ЛИЧИНОК ГЕЛЬМИНТОВ Микрометрия необходима для дифференциальной и более точной диагностики отдельных возбудителей, яйца и личинки которых имеют морфологическое сходство. Для микроскопических измерений служит специальный окуляр-микрометр, в
  5. Основные пути циркуляции яиц гельминтов в окружающей среде
    Почва. Попадание необезвреженных от яиц личинок гельминтов, цист кишечных простейших из нечистот (фекалий) в почву (рис. 13) происходит при отсутствии уборных, устройстве их на далеком расстоянии от жилья и мест работы, при их антисанитарном состоянии, использовании в качестве удобрения в садах, огородах, при опорожнении ночных горшков на территории дворов (у крыльца), совершении акта
  6. The influence of microorganisms and environmental factors on the quality of products
    Food products containing 30% water or more are a good breeding ground for microorganisms. During propagation, microorganisms secrete enzymes that decompose proteins (proteolytic), fats (lipolytic), carbohydrates (amylolytic) to intermediate or final decomposition products. At the same time, the properties of the products change for the better or for worse. The ability of microorganisms to improve
  7. Определение сроков выживаемости цист патогенных кишечных простейших в различных условиях окружающей среды
    Сведения о жизнеспособности цист патогенных кишечных простейших в окружающей среде необходимы при изучении санитарно-протозоологической и эпидемиологической ситуации и оценке эффективности проводимых профилактических мероприятий в очагах кишечных протозойных инвазий. Для постановки опытов целесообразно использовать цисты лямблий, которые при наличии одинаковых микроклиматических условий в
  8. Биоклиматограмма как метод оценки природных предпосылок для развития и выживаемости яиц геогельминтов в почве
    Известно, что развитие и выживаемость яиц аскарид в почве обусловливаются природными факторами. Определяющими из них являются солнечная радиация, температура и влажность почвы. Для определения сроков развития яиц аскарид предложено использовать формулу Боденгеймера в следующем виде: где S — срок развития яиц аскарид (сут) при температуре Т; Т° — температура среды при проведении опыта или
  9. Влияние окружающей среды на здоровье
    At present, extensive scientific material has been accumulated proving the direct impact of a number of environmental factors (climate, weather, ecological situation) on human health. На основе обширного материала биометрология (наука, занимающаяся изучением зависимости самочувствия от погоды) разработала своеобразный «календарь» болезней, характерных для средних географических
  10. PATHOLOGY CAUSED BY ENVIRONMENTAL FACTORS
    The words of the famous physician of antiquity Paracelsus (1493-1541), who believed that "Everything is poison and nothing is poisonous" can be put as an epigraph to this lecture. In fact, the problem of pathology caused by environmental factors covers almost all human diseases. Some diseases, of which there are many, are caused by direct exposure to unfavorable factors.
  11. LUNG DISEASES DUE TO ENVIRONMENTAL FACTORS
    Frank E. Speizer This chapter focuses on the perspectives of environmental assessment of lung disease. Эта оценка очень важна, поскольку устранение вредных факторов из окружающей среды часто может стать единственным средством предупреждения дальнейшего ухудшения состояния больного. In addition, the identification of these diseases in one patient may
  12. Природа неблагоприятных факторов окружающей среды.
    Ксенобиотики. Природа неблагоприятных факторов окружающей среды, приводящих к развитию патологических процессов у человека, может быть различной — химической и физической. Химические чужеродные факторы называются ксенобиотиками. Ксенобиотики (гр.xenos чужой + bios жизнь) — чужеродные для организма соединения (пестициды, препараты бытовой химии, лекарственные средства и т.п.), которые, попадая в
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