Amoebiasis, Ascariasis and Hookworm infection .pptx

community medicine:gastro intestinal infections

1. Amoebiasis, Ascariasis and Hookworm infection

2. Amoebiasis Amoebiasis is an infection with the intestinal protozoa Entamoeba histolytica. About 90% of infections are asymptomatic Remaining 10% produce a spectrum of clinical syndromes

3. Magnitude World Worldwide in distribution; India, China, Africa, South America Globally 500 million people – infected and one-tenth of infected people suffer from invasive amoebiasis. 100,000 deaths/yr, 2-60% prevalence India: 15% prevalence (3.6-47.4%) Variation according to sanitation

4. Life Cycle

5. Agent Entamoeba histolytica Two forms- Trophozoites and cysts Trophozoites Short-lived outside the human body Not important in the transmission of the disease

6. Agent Cysts: Excreted in stool. Infective to man Remain viable for several days in faeces, water, sewage and soil in the presence of moisture and low temperature. Not affected by normal amount of chlorine used in water purification Readily killed if dried, heated (to about 55 deg C) or frozen.

7. Reservoir of Infection Man- only reservoir of infection. The immediate source of infection- faeces containing the cysts. Most individuals infected with E. Histolytica are healthy carriers of the parasite. The carriers can discharge upto 1.5 x 107 cysts daily. The greatest risk is associated with carriers engaged in the preparation and handling of food

8. Host All age groups affected No gender or racial differences Severe if children, old, pregnant, PEM Household infection Develops antibodies in tissue invasion

9. Environment Low socio-economic status Poor sanitation, sewage contamination Night soil for agriculture Seasonal variation

10. Mode of Transmission Faeco -oral route Contaminated water and food Direct hand to mouth Vectors: e.g. flies, cockroaches, rats etc. Sexual contact via oro -rectal route Incubation period: 2- 4 weeks

11. Clinical Spectrum Most common- asymptomatic cases Intestinal amoebiasis – abdominal cramps with mild diarrhoea , colitis and dysentry Extra-intestinal amoebiasis – Amoebic liver abscess,rarely lungs, skin, genitalia and CNS are affected Amoeboma – inflammatory and edematous reaction around trophozoites

12. Prevention and Control Primary Prevention: Sanitation : Safe disposal of human excreta coupled with hand washing Water supply Water filtration (Sand filters) and boiling are more effective than chemical treatment of water against amoebiasis.

13. Prevention and Control Food hygiene: Uncooked vegetables and fruits can be disinfected with aqueous solution of acetic acid (5-10 per cent) or full strength vinegar Food handlers should be periodically examined, treated and educated in food hygiene practices such as hand washing Health education Health education of the public- Long -term measure

14. Secondary Prevention Early diagnosis: Microscopy: Demonstration of trophozoites containing red cells in fresh mucus passed per rectum is diagnostic. Absence of pus cells in the stool- helpful in d/d with shigellosis. Serological tests: Often negative in intestinal amoebiasis, If positive, provide a clue to extraintestinal amoebiasis. Indirect haemagglutination test (IHA) - Most sensitive serological test. Newer techniques- counter immuno-electrophoresis (CIE) and ELISA technique

15. Secondary Prevention Treatment : Symptomatic cases: Metronidazole - 30 mg/kg of body weight/day, divided into 3 doses after meals, for 8-10 days orally. Tinidazole can be used instead of metronidazole. Asymptomatic infections: If the carrier is a food handlers Oral diiodohyroxyquin , 650 mg TDS (adults) or 30-40 mg/kg of body weight/day (children) for 20 days, or Oral diloxanide furoate, 500 mg TDS for 10 days (adults)

16. Soil-transmitted Helminthiasis Group of parasitic diseases in humans caused by Intestinal roundworms (ascariasis), Hookworms (Necator americanus and Ancylostoma duodenalel Whipworm (Trichuris trichiura). About 24 per cent of the world's population are infected.

17. Mode of transmission Faeco- oral Route: Transmitted by eggs that are passed in the faeces of infected people Vegetables and salads- Not properly cooked, washed or peeled Contaminated water sources; and Children who play in soil and then put their hands in their mouth without washing them. Through Skin: Mature larvae penetrate the skin by walking barefoot on contaminated soil

18. Ascariasis An infection of the intestinal tract caused by the adult, Ascaris lumbricoides Clinically manifested by vague symptoms of nausea, abdominal pain and cough. Live worms are passed in the stool or vomited. Occasionally, they may produce intestinal obstruction or may migrate into the peritoneal cavity.

19. Burden One billion (807-1121 million) people- infected worldwide annually About 12 million acute cases 20,000 or more deaths.

20. Agent Ascaris lumbricoides lives in the lumen of small intestine The life span of an adult is between 6-12 months, maximum up to 1.5 years. Reservoir of Infection: Man is the only reservoir. Infective Material: Faeces containing the fertilized eggs The WHO definition of heavy infection of roundworm is ~ 50,000 eggs per gram of faeces

21. Life Cycle

22. Host Infection rates are higher in children- Most important disseminators of infection. Adults seem to acquire some resistance. Compete with for food and vitamin A in the intestine. Contribute to malnutrition especially in children who may show growth retardation.

23. Environment Low temperature inhibits the development of eggs. Clay soils are most favourable for the development of ascariasis eggs Human Habits: Indiscriminate open air defecation Incubation period: 18 days to several weeks

24. Symptoms Intestinal manifestations- diarrhoea, abdominal pain; General malaise, weakness, impaired cognitive, physical development The larvae migration- fever, cough, sputum formation, asthma, skin rash, oesinophilia. The adult roundworm aggregate masses can cause volvulus, intestinal obstruction or intussusception; Wandering worm can cause bowel perforation in the ileococcal region, blocking of common bile duct or may come out with vomit

25. Laboratory diagnosis Demonstration of adult worms Worm may be passed through anus, mouth, nose and rarely through ear Barium meal may occasionally reveal the presence of adult worms in the small intestine Demonstration of eggs Eggs may be detected in stool or duodenal bile aspirate by direct microscopy or after concentration of faeces Eggs may not be seen if only male worms are present

26. Laboratory diagnosis Demonstration of larvae: Ascaris larvae may be detected in the sputum during the stage of migration Serodiagnosis: Ascaris antibody can be detected by indirect haemagglutination (IHA) And immunofluorescence antibody (IFA) test These tests are useful for the diagnosis of extraintestinal – ascariasis like Loeffler’s syndrome Eosinophilia It is seen in larval invasion stage

27. Hookworm Infection Any infection caused by Ancylostoma duodenale or Necator americanus

28. Burden Ancylostoma duodenale- more prevalent in Europe and South-western Asia, Necator americanus- more prevalent in tropical Africa and in the Americas Global prevalence of hookworm was about 576-740 million cases, of these about 80 million were severely affected

29. Agent Adult worms- attached to the villi in the small intestine, mainly jejunum A duodenale and N. americanus - survive for 1 and 4 years Reservoir: Man Infective Material: Faeces containing the ova of hookworms. Immediate source of infection- soil contaminated with infective larvae.

30. Life Cycle Larvae migration

31. Host factors Age and Sex: All ages and both sexes are susceptible to infection. In endemic areas, the highest incidence- in the 15- 25 years. Nutrition: Malnutrition is a predisposing factor; Host-parasite Balance: In endemic areas, harbour the parasite without manifesting clinical signs and symptoms. Occupation: Higher prevalence in agricultural workers

32. Environmental factors Soil: Hookworm larvae live in the upper half-inch of the soil. Damp, sandy or friable soil with decaying vegetation- favours the survival of hookworm larvae. Sandy soil is more favourable than clay soil.

33. Environmental factors Temperature: For larvae- Favourable temperature- 24 to 32 deg. C Killed at 45 to 50 deg. C. The eggs fail to develop at temperatures below 13 deg. C. Oxygen: Required for the growth and development of the larvae.

34. Environmental factors Moisture: Necessary for survival; dryness is rapidly fatal. Rainfall: ≥ 40 inches (100 cm) - favourable Number of rainy days spread out evenly throughout the year- more important than total annual rainfall to keep up the moisture content of the soil. Flooding is an unfavourable factor.

35. Environmental factors Shade : Direct sunlight kills the larvae whereas shade protects them. Human Habits: Open air defecation, going barefoot, farming practices using untreated sewage, children wading in the infected mud with bare-feet and hands. These habits are compounded by social factors such as illiteracy, ignorance and low standard of living.

36. Incubation period (Prepatent period) Following infection, the prepatent period for N. americanus - 7 weeks A duodenale- 5 weeks to 9 months. This is because the invading larva of A duodenale is capable of remaining arrested or dormant in the tissues of the host for as long as 9 months and then again resume development and migration.

37. Clinical Features When filariform larva enters the skin, they cause severe local itching Erythematous papular rash may develop Scratching and secondary bacterial infection may follow This condition is called Ground itch, occurs when large number of larvae penetrate the skin, more common with necator

38. Effects of the disease Individual: Hookworm infection causes chronic blood loss and depletion of body's iron stores leading to iron-deficiency anaemia Child Health: Retarded physical growth and development Health of mothers: Increased morbidity, low birth weight babies, abortion, stillbirths and impaired lactation; Health of adults- Diminished capacity for sustained hard work. Hookworm infection causes a loss of blood plasma into the small intestine which can lead to hypoalbuminaemia

39. Effects of the disease Community: Hookworm infection exerts a significant and harmful effect on economy and quality of life of a community, especially in three major areas. Nutrition, growth and development Work and productivity Medical care costs

40. Diagnosis Demonstration of eggs in faeces by direct microscopy or by concentration methods Rhabditiform larvae may present in samples which are examined 24 hrs or more after collection

41. Whipworm Third most common soil-transmitted helminthiasis in the humans. Nearly 800 million people are infected Common in United States, South-East Asia

42. Agent Factor Live in the large intestine Can withstand cold temperatures but not desiccation. The infection is directly from the faeces. Eggs hatch in to larva after being swallowed in the intestine, It penetrates the villi and develops for a week until it re-emerges and passes to the cecum and colorectum where it attaches itself to the mucosa and becomes adult

43. Incubation period 60-90 days

44. Effect of the disease Majority of infections are mild or asymptomatic. It causes epigastric pain, nausea, vomiting, distension flatulence, weight loss. Moderate infection causes growth deficit and anaemia. Severe infection causes severe chronic diarrhea or dysentery with blood and mucous in stool, dehydration, rectal prolapse, colonic obstruction, hypoproteinaemia, chronic iron deficiency, anaemia etc.

45. Prevention and Control of STHs Primary prevention Sanitary disposal of human excreta to prevent or reduce faecal contamination of the soil, Provision of safe drinking water Food hygiene habits Health education of the community in the use of sanitary latrines Personal hygiene Changing behavioural patterns Measures of personal protection such as wearing protective footwear

46. Prevention and Control of STHs Secondary prevention Albendazole: 400 mg as a single dose (for all ages >2 years) Mebendazole: 100 mg twice daily for 3 days for all ages > 2 years. Levamisole: A single oral dose of 2.5 mg/kg of body weight (maximum 150 mg) has been recommended. Pyrantel: Effective in a single dose of 10 mg/kg of body weight with a maximum of 1 g. Treatment of anaemia and other complications: With IFA

47. Preventive chemotherapy Periodic treatment of at-risk people living in endemic areas Preschool-aged children; School aged children Women of childbearing age including pregnant women in second and third trimesters and breastfeeding mothers Adults in certain high-risk occupations, such as tea-pickers or miners .

48. Preventive chemotherapy if the prevalence of soil-transmitted helminth infection in the community is over 20 per cent- Treatment should be given once a year Prevalence is over 50 per cent- twice a year Albendazole (400 mg) and mebendazole (500 mg)

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