1. WORM INVESTITION 3 groups
Nematodes or roundworms: Intestinal human nematodes: Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Ascaris lumbricoides, Enterobius vermicularis, Trichuris trichiura
Tissue-dwelling human nematodes: Wuchereria bancrofti,
Brugia malayi, Loa loa, etc.
Trematodes or flukes e. g.Schistosoma haematobium, S. mansoni, S. japonicum,
Cestodes or tapeworm: Intestinal tapeworms: Taenia saginata, T. solium, Diphyllobothrium latum, Hymenolepis nana.Tissue-dwelling cysts or worms: Taenia solium, Echinococcus

2. Intestinal human nematodes Diseases are caused by adult nematodes living in the human gut. There are two types: • the hookworms, which have a soil stage in which they develop into larvae that then penetrate the host • a group of nematodes which survive in the soil merely as eggs that have to be ingested for their life

3. The hookworms Ancylostomiasis
Most infections by adult worms are due to 1. Ancylostoma duodenale
2. Necator americanus.

4. ANCYLOSTOMIASIS (HOOKWORM)
Ancylostomiasis is caused by parasitisation of the small intestine with Ancylostoma duodenale or Necator americanus. It is one of the main causes of anaemia in the tropics. In the early stages of infection eosinophilia is common. The adult hookworm is 1 cm long and lives in the duodenum and upper jejunum. Eggs are passed in the faeces. In warm, moist, shady soil the larvae develop into the filariform infective stage; they then penetrate human skin and are carried to the lungs . After entering the alveoli they ascend the bronchi, are swallowed and mature in the small intestine, reaching maturity 4-7 weeks after infection. Hookworm infection is widespread in the tropics and subtropics. A. duodenale is endemic in the Far East and Mediterranean coastal regions and is also present in Africa, while N. americanus is endemic in West, East and Central Africa and Central and South America, as well as in the Far East.

5. MORPHOLOGY AND LIFE CYCLE

6. HOOKWORM

8. HOOKWORMS (ADULT)

9. HOOKWORM MOUTH

10. HOOKWORM (ADULT)

11. HOOKWORM OVA

12. The larvae may cause allergic inflammation at the site of entry through the skin. When infection is heavy, the passage through the lungs may cause pulmonary eosinophilia. The worms attach themselves to the mucosa of the small intestine by their buccal capsule and withdraw blood. The mean daily loss of blood from one A. duodenale is 0.15 ml and from N. americanus 0.03 ml. The degree of iron and protein deficiency which develops depends not only on the load of worms but also on the nutrition of the patient and especially on the iron stores. In a light infection there may be no anaemia.

13. Clinical features: Dermatitis, usually on the feet (ground itch), may be experienced at the time of infection. The passage of the larvae through the lungs in a heavy infection causes a paroxysmal cough with blood-stained sputum, associated with patchy pulmonary consolidation. When the worms have reached the small intestine, vomiting and epigastric pain resembling peptic ulcer disease may occur. Sometimes frequent loose stools are passed. Iron deficiency anaemia, protein-losing enteropathy and hypoproteinaemia may develop in the undernourished. High-output cardiac failure may result from the chronic iron deficiency anaemia. The mental and physical development of children may be retarded. A well-nourished person with a light infection may be asymptomatic.

14. MICROCYTIC HYPOCHROMIC

15. Investigations
There is eosinophilia. The characteristic ovum can be recognised in the stool. If hookworms are present in numbers sufficient to cause anaemia, faecal occult blood testing will be positive and many ova will be present.
Management
single-dose treatment albendazole (400 mg) is the best choice but Mebendazole 100 mg 12-hourly for 3 days is preferred. Anaemia associated with hookworm infection responds well to oral iron even when severe; blood transfusion is rarely required and should only be used with great care in very severely anaemic patients (< 40 g/l). . The management of anaemic heart disease is best accomplished by treatment with antihelmintics and iron.

16. ASCARIS LUMBRICOIDES (ROUNDWORM)
This pale yellow nematode is cm long. Humans are infected by eating food contaminated with mature ova. Ascaris larvae hatch in the duodenum, migrate through the lungs, ascend the bronchial tree, are swallowed and mature in the small intestine. This tissue migration can provoke both local and general hypersensitivity reactions with pneumonitis, eosinophilic granulomas, bronchial asthma and urticaria.

18. Normally, the adult worms are located in the small intestine
Normally, the adult worms are located in the small intestine. In unusual circumstances, such as fever, irritation due to drugs, anaesthesia, and bowel manipulation during surgery, the worms may migrate to ectopic sites where they may give rise to severe disease.

19. Clinical features
Intestinal ascariasis causes symptoms ranging from occasional vague abdominal pain through to malnutrition. The large size of the adult worm and its tendency to aggregate and migrate can result in severe obstructive complications. In endemic areas ascariasis causes up to 35% of all intestinal obstructions, most commonly in the terminal ileum. Obstruction can be complicated further by intussusception, volvulus, haemorrhagic infarction and perforation. Other complications include blockage of the bile or pancreatic duct and obstruction of the appendix by adult worms.

20. Investigations
The diagnosis is made microscopically by finding ova in the faeces. Adult worms are frequently expelled rectally or orally. Occasionally, the worms are demonstrated radiographically by a barium examination. There is eosinophilia.
Management
Mebendazole 100 mg 12-hourly for 3 days. Albendazole 400 mg or piperazine 4 g or ivermectin (150–200 μg/kg) as a single dose is effective for intestinal ascariasis. Patients should be warned that they may expel numerous whole, large worms. Obstruction due to ascariasis should be treated with nasogastric suction, piperazine and intravenous fluids.

21. Prevention
Community chemotherapy programmes have been used to reduce Ascaris infection. The whole community can be treated every 3 months and over several years. Alternatively, schoolchildren can be targeted; treating them lowers the prevalence of ascariasis in the whole community.

22. Enterobiasis
Enterobiasis is a disease caused by Enterobius vermicularis infestation.
Children are more often involved than adults. It occurs in groups such as families living together, and in army camps.

23. This helminth is common throughout the world
This helminth is common throughout the world. It affects children especially. After the ova are swallowed, development takes place in the small intestine, but the adult worms are found chiefly in the colon. The male is approximately 5 mm long with a diameter of 0.1 to 0.2 mm. The female is approximately 13 mm long.
Clinical features
The gravid female worm lays ova around the anus, causing intense itching, especially at night. The ova are often carried to the mouth on the fingers and so reinfection takes place. In females the genitalia may be involved. The adult worms may be seen moving on the buttocks or in the stool.

24. Enterobius vermicularis

25. Enterobius vermicularis OVUM

27. Investigations: Ova are detected by applying the adhesive surface of cellophane tape to the perianal skin in the morning. This is then examined on a glass slide under the microscope. A perianal swab, moistened with saline, is an alternative method for diagnosis.
Management: A single dose of mebendazole 100 mg, albendazole 400 mg or piperazine 4 g is given and may be repeated after 2 weeks to control auto-reinfection. Where infection constantly recurs in a family, each member should be treated as above. During this period all nightclothes and bed linen are laundered. Fingernails must be kept short and hands washed carefully before meals. Subsequent therapy is reserved for those family members who develop recurrent infection.

28. Tapeworm Infestation (Cestoda)

29. Cestodes are ribbon-shaped worms which inhabit the intestinal tract
Cestodes are ribbon-shaped worms which inhabit the intestinal tract. They have no alimentary system and absorb nutrients through the tegumental surface. The anterior end, or scolex, has suckers for attaching to the host. From the scolex arises a series of progressively developing segments, the proglottides, which when shed may continue to show active movements. Cross-fertilisation takes place between segments. Ova, present in large numbers in mature proglottides, remain viable for weeks and during this period they may be consumed by the intermediate host. Larvae liberated from the ingested ova pass into the tissues. Humans acquire tapeworm by eating undercooked beef infected with Cysticercus bovis, the larval stage of Taenia saginata (beef tapeworm), undercooked pork containing the larval stage of T. solium (pork tapeworm), or undercooked freshwater fish containing larvae of Diphyllobothrium latum (fish tapeworm). Usually only one adult tapeworm is present in the gut but up to ten have been reported.

30. CESTODA (TAPEWORMS) TYPES
The most important cestoda that infest humans are:
1. Taenia saginata
2. Taenia solium
3. Echinococcus
4. Diphyllobothrium (fish tapeworm)
5. Hymenolepis

31. 1. Primary host:
Humans are the primary host in all (adult live in intestine) except Echinococcus, in which the human is intermediate host (larva within tissues) and dogs are primary host (final host).
2. Intermediate Hosts:
Cattle: T. Saginata, Pigs: T. Solium, Fishs: Diphyllobothrium, Human, sheep and others: Echinococcus.
3. Rarely the human becomes intermediate host for T. solium if he/she ingest eggs accidently.

32. The primary host (human or others) passes the mature segments containing ova which remain viable for Ws in the soil and may be consumed by intermediate hosts (cattle, sheep, pig, fishes) and change to larva in their tissues.
When humans are the primary host, the adult cestode is limited to the intestinal tract. When humans are the intermediate hosts, the larvae are within the tissues, migrating through the different organ systems.

33. T. saginata
Most worms are solitary (AL- DODDA AL-WAHEDA), and worms may live 30 years and may reach 20 meters in length

34. Taenia saginata
Infection with T. saginata occurs in all parts of the world. The adult worm may be several metres long and produces little or no intestinal upset in human beings, but knowledge of its presence, by noting segments in the faeces or on underclothing, may distress the patient. Ova may be found in the stool. The ova of T. saginata and T. solium are indistinguishable microscopically.
Praziquantel is the drug of choice, and prevention depends on efficient meat inspection and the thorough cooking of beef. Niclosamide is an alternative .

36. T. Ova The ova of T. saginata and T
T. Ova The ova of T. saginata and T. solium are indistinguishable microscopically.

37. T. Saginata The adult worm may be several meters long

38. Cattles intermediate host for T. saginata

39. Taenia solium
T. solium, the pork tapeworm, is common in central Europe, South Africa, South America and parts of Asia. It is not as large as T. saginata. The adult worm is found only in humans following the eating of undercooked pork containing cysticerci.
CYSTICERCOSIS Human cysticercosis is acquired by ingesting tapeworm ova, either by ingesting ova from contaminated fingers or by eating contaminated food. The larvae are liberated from eggs in the stomach, penetrate the intestinal mucosa and are carried to many parts of the body where they develop and form cysticerci, cm cysts that contain the head of a young worm. They do not grow further or migrate. Common locations are the subcutaneous tissue, skeletal muscles and brain.

40. T. Solium scolex with hooks and suckers

41. Pigs intermediate host for T.solium

43. Clinical features
When superficially placed, cysts can be palpated under the skin or mucosa as pea-like ovoid bodies. Here they cause few or no symptoms, and will eventually die and become calcified.
Heavy brain infections, especially in children, may cause features of encephalitis. More commonly, however, cerebral signs do not occur until the larvae die, 5-20 years later. Epilepsy, personality changes, staggering gait or signs of internal hydrocephalus are the most common features.

44. Investigations: Calcified cysts in muscles can be recognised radiologically. In the brain, however, less calcification takes place and larvae are only occasionally demonstrated radiologically; usually CT or MRI will show them. Epileptic fits starting in adult life should suggest the possibility of cysticercosis if the patient has lived in or travelled to an endemic area. The subcutaneous tissue should be palpated and any nodule excised for histology. Radiological examination of the skeletal muscles may be helpful. Antibody detection by fluorescent antibody test, ELISA or immunoblotting is available for serodiagnosis.

45. Management and prevention
Niclosamide, followed by a mild laxative (after 1-2 hours) to prevent retrograde intestinal autoinfection, is useful only for the intestinal infection. Praziquantel improves the prognosis of cerebral cysticercosis; the dose is 50 mg/kg in three divided doses daily for 10 days. Albendazole, 15 mg/kg daily for a minimum of 8 days, has now become the drug of choice for parenchymal neurocysticercosis. Prednisolone, 10 mg 8-hourly, is also given for 14 days, starting 1 day before the albendazole or praziquantel. In addition, anti-epileptic drugs should be given until the reaction in the brain has subsided. Operative intervention is indicated for hydrocephalus. Studies from India and Peru suggest that most small solitary cerebral cysts will resolve without treatment.

46. Cooking pork well will prevent infection with T. solium
Cooking pork well will prevent infection with T. solium. Cysticercosis is avoided if food is not contaminated by ova or segments. Great care must be taken by nurses and other adults while attending a patient harbouring an adult worm.

47. Echinococcus infestations
The disease is common in the Middle East, North and East Africa, Australia and Argentina.

48. By handling a dog or drinking contaminated water, humans may ingest eggs . The embryo is liberated from the ovum in the small intestine and gains access to the blood stream and thus to the liver.

50. CLINICAL PICTURE

51. CLINICAL MANIFESTATION
A hydatid cyst is typically acquired in childhood and it may, after growing for some years, cause pressure symptoms. These vary, depending on the organ or tissue involved. In nearly 75% of patients with hydatid disease the right lobe of the liver is invaded and contains a single cyst. In others a cyst may be found in lung, bone, brain or elsewhere.

52. 1. The patient remains asymptomatic until the cysts cause a mass effect on the organ, which can be 5-20 years after the initial infestation.
2. These cysts do not metastasize, but they may be disseminated by accidental spillage.
3.Most patients have single organ
involvement and most will have a solitary cyst .

53. Hepatic form:
1. palpable R hypochondrial mass and jaundice can occur.
2. Rupture of liver hydatid cyst into peritoneal cavity may cause anaphylactic shock.

54. Pulmonary: 25%
cystic rupture may result in symptoms of cough, chest pain, and hemoptysis.
Crape-like material may be coughed.
Rarely pneumothorax, with or without pleural effusion and anaphylaxis can occur following cyst rupture.
Other organs: Brain, Kidney, Bone, Adrenal glands.

55. DIAGNOSIS
The diagnosis depends on the clinical, radiological and ultrasound findings in a patient who has lived in close contact with dogs in an endemic area. Complement fixation and ELISA are positive in 70-90% of patients.

56. HYDATID CYSTS OF LIVER AND LUNG

57. MANAGEMENT
Hydatid cysts should be excised wherever possible. Great care is taken to avoid spillage and cavities are sterilised with 0.5% silver nitrate or 2.7% sodium chloride. Albendazole (400 mg 12-hourly for 3 months) is used for inoperable disease, and to reduce the infectivity of cysts pre-operatively. Praziquantel 20 mg/kg 12-hourly for 14 days kills protoscolices perioperatively.

58. Prevention
Prevention is difficult in situations where there is a close association with dogs and sheep. Personal hygiene, satisfactory disposal of carcasses, meat inspection and deworming of dogs can greatly reduce the prevalence of disease.

59. Diphyllobothriasis
Is an infection that occurs from eating raw or undercooked fish infected with Diphyllobothrium species.
Diphyllobothrium organisms are present in lakes, rivers, and deltas of freshwaters. Eskimos in western Alaska and the West Coast of the United States are frequent hosts. Also in finland

60. The cestode is not invasive, but it does absorb a large amount of vitamin B-12 and interferes with vitamin B-12 absorption from the ileum, producing a megaloblastic anemia that resembles pernicious anemia (clinically and hematologically). Patients may complain of neurologic symptoms resembling pernicious anemia (eg, paresthesias, difficulty with balance, dementia or confusional states).