Exercise 18. Say whether these sentences are true or false, and if they are false say why.
1. Trematodes Fasciola or liver flukes have an indirect life cycle with numerous domestic and wild mammals as final hosts, and snails as intermediate hosts.
2. The usual larval stages of most flukes species are miracidia, sporocysts, rediae and cercariae, all of which are infective for the final host.
3. Liver flukes are quite benign for their hosts.
4. Liver flukes can destroy the liver tissues, cause bleeding, damage the bile ducts, produce toxins harmful for the liver.
5. The major economic damage for livestock is high mortality.
6. This infection has its typical symptoms, which are recognizable even in the early stages.
7. Such symptoms as anemia, edema, digestive disturbances, and emaciation are seen in sheep suffering from acute fasciolosis.
Exercise 19. Read the additional information about the life stages of flukes and describe the life cycle of Fasciola.
Miracidium is the flat ciliated larva of a trematode that hatches from the egg and penetrates a suitable snail intermediate host.
Sporocyst is the second larva of a trematode worm that produces redia larvae by asexual reproduction.
Redia is the third larva of flukes that has simple locomotory organs, pharynx, and intestine and gives rise to other rediae or to cercariae.
Cercaria is a larval form of trematode worms that has a short tail and resembles an immature adult.
Exercise 20. Match the term with its definition.
| bleeding | a condition in which there is difficulty in emptying the bowels |
| rotational grazing | the thickening and scarring of connective tissue |
| emaciation | a small organ beneath the liver, in which bile is stored after secretion by the liver and before release into the intestine |
| fibrosis | the practice of moving grazing livestock between pastures to allow time for plants to regenerate |
| gall bladder | the state of being abnormally thin or weak |
| constipation | the flow of blood from a ruptured blood vessel |
Exercise 21. Give the English equivalents of the Russian words in brackets.
1. Adult flukes are localized in the (желчныепротоки) of the liver or (желчныйпузырь) of numerous domestic and wild mammals. 2. (Распространенностьистепеньзаболевания) in a particular region depends strongly on ecologic and climatic conditions and on (принципыведенияживотноводческогохозяйства). 3. Migration of immature flukes (разрушатьткани) and (вызыватькровотечение). 4. Flukes produce toxins that (нарушатьнормальноефункционированиепечени). 5. Besides fatalities, the major (экономическийущерб) is the reduced (наборвеса) of young animals and the (признаниенекондиционным) of livers at slaughter.6. To diminish fluke infestation (пастбищеоборот) is highly recommended.
Exercise 22. Translate from Russian into English.
1. Печеночные сосальщики встречаются повсеместно, но особенно их много в районах с влажным умеренным климатом. 2. Этот червь является одним из самых опасных паразитов пастбищного скота. 3. Шипы на поверхности тела червя вызывают раздражение и воспаление тканей. 4. Желчные протоки повреждаются: они утолщаются, отвердевают и даже могут закупориваться. 5. Даже небольшое заражение этими червями снижает молочную производительность. 6. Острая инфекция приводит к полному отказу печени и смерти в течение нескольких дней.
Exercise 23. Test yourself by answering the following questions to see how much you remember and understand.
1. What is the causative agent of fasciolosis?
2. Describe the life cycle of the helminth.
3. How are the organs affected by the worms?
4. What are the major economic damages?
5. What is the difference between chronic and acute fasciolosis?
6. How to diagnose the disease?
7. What preventive measures are used in endemic regions?
TEXT D
TRICHURIASIS
VOCABULARY LIST TO TEXT D
| adverseadj | [ədˈvɜːs] | неблагоприятный |
| bedding n | [ˈbedɪŋ] | подстилка |
| confined adj | [kənˈfaɪnd] | ограниченный |
| cuticle n | [ˈkjuːtɪkl ] | кутикула |
| droppings n | [ˈdrɒpɪŋz] | помет, навоз |
| gravel n | [ˈɡrævəl] | гравий |
| handle n | [ˈhændl] | ручка |
| manure n | [məˈnjʊə] | навоз |
| pen n | [pen] | загон |
| ranging adj | [ˈreɪndʒɪŋ] | пасущийся |
| run n | [rʌn] | вольер |
| sawdust n | [ˈsɔ:dʌst] | опилки |
| thorough adj | [ˈθʌrə] | тщательный |
| trichuriasis n | [ˌtrɪkǝˈraɪsǝs] | трихуроз |
| whip n | [wɪp] | кнут |
| whipworm n | [wɪpˈwɜːm] | власоглав |
Trichuriasis, also known as whipworm infection, is an infection caused by parasitic roundworms belonging to the genus Trichuris. Different species of whipworms infest different species of animals. The most important species inhabit the large intestine of cattle, sheep, goats, pigs, dogs, cats, and humans. Infection occurs worldwide in warm and humid climates and in temperate climates during warmer months, especially in areas where sanitation and hygiene are poor. The severity of the disease depends on the number of worms and the condition of the host.
Adult worms are 3 to 8 cm long and have a whitish to yellowish color. Their shape resembles a whip with its handle, with posterior end thicker than anterior, hence the name “whipworm”. The worm’s body is covered with a cuticle, which is flexible but rather tough.
Similar to other nematodes whipworms have a direct life cycle. Female worms produce several thousand eggs per day. These eggs are shed with the host’s feces. Because of their resistance to cold and dry weather, the eggs can remain infective in the soil for years. Final host ingests eggs with contaminated food or water.The larvae hatch out of the eggs in the small intestine, enter the mucosa there and move forward to the cecum where they penetrate the mucosa and complete development to adults.
Immature larvae that penetrate the lining of the large intestine cause irritation. Later adult wormsfeeding on blood damage the wall of the cecum. Nevertheless, light infestationsfrequently have no symptoms. Massive infections can cause intestine inflammation (enteritis), ulceration, bleeding and subsequent anemia, bloody diarrhea, disturbed fluid absorption, dehydration, lack of appetite and weight loss. Some animals, especially the young ones, may even die.
Diagnosis is based on the detection of eggs in the feces. Adult worms may also be seen in the host's droppings.
Preventing whipworm infections in free ranging livestock is not an easy task: theeggs can remain infective for years on pasture and are extremely resistant to adverse weather conditions. Serious, live threatening infections do not happen too often. In confined livestock facilities,thorough hygiene measures including manure removal are highly recommended in endemic regions.
To prevent whipworm infections in dogs and cats daily removal of droppings is very important as well as frequent change ofbedding (sawdust, sand, gravel) of playing grounds, runs,pens, cages, especially where numerous pets live together. Young animals must be particularly protected because they are more likely to suffer from whipworm infections.
Many anthelmintic drugs are effective against trichuriasis in livestock and pets. Unfortunately, animals that were successfully treated do not remain protected against new infections.Periodic deworming of animals may help to keep them worm-free.
EXERCISES TO THE TEXT
Exercise 24. Look through the text and find the information about:
- trichuriasis causative agent;
- animals that are susceptible to trichuriasis;
- main characteristics of the causative agent;
- ways of transmission of trichuriasis;
- harm that may be caused by massive infections;
- prevention of trichuriasis.