Gut parasites in general practice

Transcription

1 Gut parasites in general practice A biased account Dr. Samson Wong Department of Microbiology The University of Hong Kong

2 Classification of parasites Protozoa Helminths Arthropods Nematodes (roundworms) Trematodes (flukes) Cestodes (tapeworms) Insects Arachnids Blood and tissue Luminal

3 Why do we need to know parasites? Clinical significance. Public health significance. Global significance. International travel. Leisure Work Missionary Immunocompromised hosts.

4 Clinical suspicion Clinical signs and symptoms. Travel history. Exposure history. e.g. arthropod bites, food and drinks, transfusion, animal contact. Predisposing factors. e.g. HIV infection, immunosuppressive therapy. Unexpected histological findings.

5 Diagnosis With few exceptions, a competent laboratory service is needed to confirm the diagnosis. Macroscopic examination Microscopic examination Serology Culture Nucleic acid amplification

6 Transmission of parasitic infections Environment Host 1 Host 2 Intermediate hosts / vector ( 1) Physical Socio-economic, cultural Biological

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9 What we may see? Queen Mary Hospital (Jan May 2003) Total specimens examined = Positive identifications = 242 (5.5%).

10 Cyclospora 1 (0.4%) Sarcoptes scabiei 57 (23.5%) Plasmodium falciparum 1 (0.4%) Clonorchis sinensis 156 (64.5%) Adult worm 2 Ova 154 Entamoeba histolytica 1 (0.4%) Trichuris trichiura 1 (0.4%) Enterobius vermicularis 2 (0.8%) Queen Mary Hospital (Jan May 2003) Ascaris lumbricoides 6 (2.5%) Adult worm 5 Ova 1 Giardia lamblia 7 (2.9%) Strongyloides stercoralis 10 (4.1%) Positive: 242 Gut: 76.0%

11 Temporal trend of common gut parasites, Queen Mary Hospital Total number Number positive % 23.7% 21.9% 23.2% 5.5% Clonorchis sinensis % 55.0% 58.0% 63.4% 64.5% Ascaris lumbricoides % 22.4% 27.2% 16.7% 2.5% Trichuris trichiura % 19.4% 13.2% 16.1% 0.4% Hookworms % 1.8% 0.8% 2.3% 0% Strongyloides stercoralis % 0.5% 0.4% 0.9% 4.1% Enterobius vermicularis % 0.1% 0% 0.2% 0.8%

12 % of all positive identifications 70 Temporal trend of common gut parasites, Queen Mary Hospital Clonorchis sinensis Ascaris lumbricoides Trichuris trichiura Hookworms Strongyloides stercoralis Enterobius vermicularis

13 In the hospital setting, We are seeing fewer (common) parasitic infections. Clonorchis sinensis is still the commonest. Marked decreases in prevalence of geohelminths: Ascaris lumbricoides Trichuris trichiura Hookworms Still have ubiquitous parasites like Enterobius vermicularis. Marked increase in strongyloidiasis.

14 % of all specimens Clonorchis sinensis Trichuris trichiura Hookworm Ascaris lumbricoides Strongyloides stercoralis Enterobius vermicularis Kam KM. J Trop Med Hyg Huang CT, Wong MM, Ma SL, Sun T. Postmortem and laboratory examinations for intestinal helminths in Hong Kong. Trop Med 1969;11: Duchastel P. Prevalence of parasites in stools of Hong Kong residents and Indochinese refugees applying for emigration to Canada: retrospective study over two-year period ( ). In Current Perspectives in Parasitic Diseases (ed. RC Ko), Hong Kong University, 1984, p Kam KM. Intestinal parasites in Hong Kong. J Trop Med Hyg 1994;97:

15 Pathophysiology Local tissue irritation / inflammation / invasion. Physical obstruction. Blood loss. Migration. Dissemination. Co-factor in carcinogenesis.

16 Common clinical manifestations of enteric parasites Asymptomatic. Diarrhoea, dysentery, abdominal symptoms. Pruritus ani. Eosinophilia. Pneumonitis. Anaemia. Malabsorption. Hepatobiliary complications, pancreatitis. Intestinal obstruction. Appendicitis. Disseminated infection. Malignancy.

17 Eosinophilia Not a feature of protozoal infections. Helminthic infections Loaisis Schistosomiasis Filariasis Trichinosis Hookworms Cutaneous / visceral larva migrans Fascioliasis Ascariasis

18 Asymptomatic infection: incidental finding Enteric parasites found on routine examination.

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24 Asymptomatic infection: incidental finding Enteric parasites found in histopathological sections.

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27 Clonorchis sinensis Asymptomatic. Obstructive jaundice. Biliary stones, cholangitis, liver abscess. Recurrent pyogenic cholangitis. Cholangiocarcinoma. Acute pancreatitis, cholecystitis.

28 Asymptomatic infection: incidental finding M/71. PR bleeding. Colonoscopy Ulcerative growth at 8 cm from anal verge. Low anterior resection. Histopathology Moderately undifferentiated adenocarcinoma involving the entire thickness of bowel including serosa. Postoperative day 8 Consultation.

29 Courtesy of Dr. F Loong

30 Courtesy of Dr. F Loong

31 Courtesy of Dr. F Loong

32 Asymptomatic infection: accidental finding F/26, Bangladeshi. 9 weeks pregnant. Admitted for Hyperemesis gravidarum Hyperthyroidism Vomitus sent to microbiology laboratory. Same sort of vomitus 1 week ago!

33 Asymptomatic infection: accidental finding F/67, housewife. CA breast, right mastectomy 2 years ago. Fever, abdominal pain, vomiting for 1 day C, GCS 12/15. Neck rigidity +. CT brain: no SOL. Clinical diagnosis: meningitis. Empirical iv cefotaxime. Vomitus sent to microbiology laboratory.

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36 Asymptomatic infection: accidental finding A man passing out a worm (or rather, a segment of a worm).

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39 What species is this? Be extremely careful when you handle this!!! Diphyllobothrium latum.

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41 Symptomatic disease F/4. Pakistani girl. Pruritus ani.

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47 Severe disease: acute, local M/54, British, diabetic. Frequent traveller. Last visited Cyprus 2 months ago. Fever (38.5ºC), watery diarrhoea (5-6/d), mucus +, no blood; mild abdominal tenderness. CT scan in New Zealand. Came back to Hong Kong for further treatment.

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54 Courtesy of Dr. F Loong

55 Courtesy of Dr. F Loong

56 Severe disease: acute, local M/36. PR bleeding for 6 months. Mucus in stool +. Tenesmus. Proctoscopy: unremarkable. Colonoscopy A few shallow ulcers in caecum. Rest of colon normal. Sigmoidoscopy (2 months later) Multiple shallow ulcers at lower rectum up to 10 cm.

57 Courtesy of Dr. P Fan

58 Courtesy of Dr. P Fan

59 Venereal transmission of intestinal parasites Prevalence Potentially pathogenic enteric parasites found in 16-57% of homosexual men. Correlated with a history of anilingus. Commonly: Entamoeba histolytica (? E. dispar). Giardia lamblia. Enterobius vermicularis.

60 Severe disease: chronic, local.

61 Courtesy of Dr. F Loong

62 Courtesy of Dr. T Shek

63 Severe disease: acute, systemic. M/64. Chronic rheumatism. Admitted for decreased general condition, increasing dullness. Consulted for high fever noted after admission. Found to have neck rigidity. CSF TCC 386, N 88%, L 10%, M 2%.

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70 Severe disease: acute on chronic, systemic.

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80 Your role in parasitic infections Diagnosis Treatment Notification Prevention

81 Your role in parasitic infections Diagnosis Treatment Notification Prevention

82 Your role in parasitic infections Diagnosis Treatment Notification Prevention

83 Prevention of parasitic infections Elimination of parasites in the reservoir. Elimination of vectors. Avoiding exposure to parasites and vectors. Chemoprophylaxis.? Vaccines.

84 Prevention of parasitic infections Elimination of parasites in the reservoir. Elimination of vectors. Avoiding exposure to parasites and vectors. Chemoprophylaxis.? Vaccines. Ctenopharyngodon idellus