1. Intestinal Nematodes and Eosinophilia
Patricia F Walker, MD, DTM&H
Medical Director, HealthPartners Center for International Health
Associate Professor, Division of Infectious Disease and International Medicine
University of Minnesota
Healthcare in the Global Village: Serving Refugees in Indiana
Indianapolis, Indiana September 25, 2009

2. Parasitic Helminths Trematodes (flukes) Cestodes (tapeworms)
Venous system: Schistosoma
Biliary tract: Clonorchis, Fasciola
Lung: Paragonimus
Cestodes (tapeworms)
Taenia saginata, Taenia solium, H. nana
Nematodes (roundworm)
Intestinal
Blood, lymphatic, subcutaneous

3. Lecture Overview
General Facts about Intestinal Nematodes
4 major intestinal nematodes: Ascaris, Trichuris, hookworm and Strongyloides
Public Health Implications
Lifecycle
Clinical presentation
Treatment
Trends in Intestinal Parasitism among Refugees

4. General Facts about Intestinal Nematodes
Frequently nonspecific symptoms
Often asymptomatic until worm burden becomes large
Weight loss, GI discomfort
Diarrhea or fever from nematodes is uncommon
Polyparasitism
Burden is greatest in children

5. General Facts about Intestinal Nematodes
Tropical and subtropical predominance
Don’t multiply in host
2 exceptions
Infection limited to life span of worm unless reinfection occurs
Lifespan: 2 months – 5 years
Rare Exceptions:
Strongyloides, C. philippinensis: autoinfection
Pinworm: self-reinfection

6. Soil Transmitted Helminths (STH) = Geohelminths
Part of development occurs in the soil
Average 3 – 4 weeks in soil until infective
Infection via eggs in contaminated soil (Ascaris, Trichuris) or skin penetration (hookworm)
Ecology of geohelminth infection In tropical and subtropical areas, wet soil (such as that found at the edges of rice fields, rubber plantations and the surroundings of villages in areas of high rainfall) supports the maturation of hookworm larvae from eggs deposited by indiscriminate defaecation; this limits their geographical distribution. In contrast, the well-protected eggs of nematodes with a direct cycle of transmission (Ascaris lumbricoides, Trichuris trichiura) can survive in drier conditions even at freezing temperatures.

7. Soil Transmitted Helminths (STH)
Infection rates and burden of disease greatest among conditions of poverty, poor sanitation

8. Guatemalan Children With Soil–Transmitted Helminth Infections
Stunting, anemia, loss of IQ, diminished school performance
Many years of lost primary schooling attributable to STH

9. Parasite Prevalence in Village of Paquila, Guatemala
100 80 60
Prevalence (%) 40 20
0 – 3
4 – 7
8 – 12
Age Class (y)
Ascaris
Trichuris
Hookworm
Strongyloides

10. Highest Worm Burdens in School-aged Children

11. Growth Curve of Child With Soil-transmitted Infection

12. Ascaris lumbricoides
1/8th the world’s population infected
Largest of nematodes infecting humans
Adult habitat: small intestine (jejunum)
Obligatory extra-intestinal migration (eosinophilia)
Lifespan: 1 – 2 years
Intensity of infection greatest in children, ages 5 – 10 years

13. Ascaris infection in Haiti and Paraguay

14. Ascaris Lumbricoides
Eighty-nine hookworms and 81 Ascaris. This demonstration induced many to apply for treatment (Brazil).

15. Geographic prevalence highest in warm, wet climates
Ascaris
Geographic prevalence highest in warm, wet climates
1 adult female = 200,000 eggs/day

16. Pre-patency: 2 months
Pneumonitis: 4 – 16 days after infection, short duration (~3 wks)

17. Löeffler Syndrome (Pneumonitis)
Transverse sections of Ascaris larvae in pulmonary alveoli
460 Transverse sections of Ascaris lumbricoides larvae in the pulmonary alveoli This post-mortem specimen shows transverse sections of larvae and eosinophilic infiltration of the alveolar walls. (Courtesy of Dr A M de Oliviera Ramos.) (H&E × 300)

18. Ascaris lumbricoides
Larval phase: eosinophilia, pneumonitis
Adult phase:
Malnutrition, Impaired Physical Growth
Mild abdominal discomfort → → Small bowel obstruction (in children, few as 60 worms)
Wandering ascaris: biliary tract obstruction, cholangitis, pancreatitis, liver abscess
Treatment: Albendazole x 1 dose

19. Adult Ascaris worms migrating in liver
465 Adult roundworms migrating in liver The adult worms have a marked tendency to penetrate any available hole in their vicinity and may escape through abdominal fistulae following operation. They may also lead to biliary obstruction and occupy the appendix.

20. Ascaris causing intestinal obstruction.

21. Acute G.I. Obstruction from Ascaris

22. Interesting e mails…
Sent: Monday, April 04, :32 PM To: Subject: health needs
I got your address from my mother- Linda  A.
I am an ELL teacher and have many students from Liberia.  I had a student complain about coughing up a long white worm as he was eating a lemon at lunch.  I sent him to the nurse at school, as he said this was the second time it has happened to him.  She sent him back to class saying there wasn't enough to tell anything at this point.  Is there anything you can suggest, or anywhere I can direct his parents?
Thanks for your help!
Michelle R  

23. Ascaris (roundworm):
The only nematode ever coughed or vomited up

24. Whipworm: Trichuris trichiuria
Adult habitat: caecum, colorectum
No extra-intestinal phase
Lifespan: years
90% infections are asymptomatic
Symptoms with heavy infections
Intensity of infection peaks by age 10

25. Pre-patency: 2 months

26. Whipworm: Trichuris trichiuria
Clinical Features:
Asymptomatic
Physical Weakness, Anemia
Stunted Growth, Cognitive Deficits
Stool frequency (12+/day), nocturnal stooling
Trichuris dysentery syndrome
Trichuris colitis
Rectal prolapse
Treatment: Albendazole x 3 days.

27. Whipworm: Trichuriasis Colitis

28. Rectal Prolapse from Trichiuriasis

29. Whipworm Egg: 2 polar plugs

30. The Human Hookworms
Necator americanus Ancylostoma duodenale

31. Hookworm: Necator americanus & Ancylostoma duodenale
One – tenth the world’s population infected
Significant cause of anemia & protein malnutrition
Adult habitat: small intestine
Lifespan:
~ 1 year (A. duodenale)
~ years (N. americanus)
Worm burdens do not decline in adult years

32. Typical Age and Intensity of Infection Relationship
100 90 80
Trichuris 70
Hookworm 60
Mean Worm Burden (%) 50
Ascaris 40 30 20 10 10 20 30 40
Mean Age (y)

33. Human Hookworm Infection
~600 million cases worldwide (rural poverty >>> urban slums) 44 million pregnant women infected Iron-deficiency anemia: Physical & Intellectual Retardation Necator americanus is the predominant hookworm species

34. Life Cycle of Hookworm
Pre-patency: months - year

35. Adult worms injure their host by causing intestinal blood loss:
Hookworm-Blood Loss
Adult worms injure their host by causing intestinal blood loss:
Anticoagulants, Hemolysins, and Hemoglobinases
30 to 200 μL blood per day per hookworm
Intestinal blood loss and Iron Deficiency Anemia

36. Adult Hookworms in Situ (1 cm)
Adult size: 0.5 ─ 1 cm
Daily eggs per worm: 5 ─ 20,000
430 Adult hookworms in situ The worms are about 1 cm long and characteristically curved. They are attached by their buccal capsules to the villi of the small intestine. (Natural size)

37. Hookworm: Clinical Features:
Ground-itch –> Dry cough, wheezing (1-2 wks later) in primary infection
Abdominal discomfort
Progressive iron-deficiency anemia
40 – 160 worms associated with Hgb < 11 g/dL
Failure to thrive, extreme fatigue
IQ loss
Treatment: Albendazole x 1 dose

38. Hookworm Disease
Pallor and
Facial Edema
Anasarca

39. At-Risk Populations for Hookworm Disease
Women and Children: Low Iron Stores
Children:
Physical growth stunting
Cognitive deficits and intellectual retardation
Women of Child-bearing age
Puberty
Menstruation
Pregnancy
Increased Maternal Mortality (anemia)
Low Birthweight
Infant Mortality

40. School Based Deworming
In 2001, (WHO) adopted a resolution aimed at the “deworming” of 75 percent of all at-risk school-age children by 2010, Prevention and
Improvements in iron, Hgb status
Improved Cognition, Educational Achievement
Reduction in school absenteeism
Reduction in community helminth transmission of ascariasis & trichuriasis

41. Control Anti-helminthic drugs:
50 million tablets of mebendazole donated per year by Johnson & Johnson
Albendazole available from GlaxoSmithKline for 2¢ per pill
Currently no vaccine exists for ascariasis or trichuriasis
Human Hookworm Vaccine Initiative (HHVI): Phase I trials

42. Strongyloidiasis: Strongyloides stercoralis
Worldwide prevalence: ~100 million
Adult habitat: duodenum, jejunum
Lifespan: unknown. Ongoing autoinfection.

43. Strongyloidiasis - Clinical Presentation
Asymptomatic eosinophilia
Abdominal pain
Dermatitis - larva currens
Pulmonary infiltrates with eosinophilia
Dissemination with sepsis

44. Strongyloides. by ethnicity Regions Hospital, St
Strongyloides* by ethnicity Regions Hospital, St. Paul, MN 1/1/88 - 9/1/98
Ethnicity N %
Cambodian
Hmong
Vietnamese
African
Hispanic 4 2.5
Laotian
Unknown %
Microbiology Lab Regions Hospital
* Positive stool specimens

45. Documented length of infections in years
Adapted from Hospital for Tropical Disease
London, 1997

46. Pruritic Larva Currens from Strongyloides
Larva currens = autoinfection with Strongyloides filariform larvae Moves rapidly (2 ─ 10 cm/hr), lasts shorter than CLM

47. Filariform Larvae (penetrating)
Strongyloides Rhabditiform Larvae may transform to Filariform Larvae… penetrating perianal skin and bowel mucosa
Rhabditiform Larvae
Adult
Filariform Larvae (penetrating)
Copyright © 2006, 1999 by Elsevier Inc.

48. Strongyloidiasis Hyperinfection: Strongyloides stercoralis
intestinal perforation
hemorrhagic pneumonia
shock, sepsis, gram-negative meningitis
eosinophilia may be limited

49. Vietnamese male, in US for 8 years, developed fever, rash and pneumonia after being placed on steroids for uveitis.

50. FIGURE 285-2. Eggs and larvae of common intestinal roundworms
FIGURE Eggs and larvae of common intestinal roundworms. Clockwise, beginning at upper left: Ascaris lumbricoides; Trichuris trichiura; hookworm; Enterobius vermicularis; Strongyloides stercoralis; and embryonated hookworm egg. (From DPDx, website for laboratory diagnosis of parasitic diseases of the Division of Parasitic Diseases, National Centers for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA: [

52. Good news: Pre-departure treatment for intestinal parasites in US bound refugees
Since May, 1999 CDC has implemented empiric treatment with single dose albendazole 600 mg for all refugees departing from sub Saharan Africa, and for selected groups, such as Hmong arriving from Thailand in 2005

53. Prevalence of Intestinal Parasites Among Refugees Arriving in Minnesota, pre-May 1999 (n = 4,584)
Giardia
Hookworm
Trichuris
Ascaris
Strongyloides
Any helminth
Multiple helminths
21.5%
Percentage
10.2%
8.7%
8.2%
3.7%
3.1%
2.3%
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Giardia
Hookworm
Trichuris
Ascaris
Strongy -loides
Any helminth
Multiple helminths

54. Prevalence of Intestinal Parasites Among Refugees Arriving in Minnesota, pre/post-May (n = 18,015)
Giardia
Hookworm
Trichuris
Ascaris
Strongyloides
Any helminth
Multiple helminths
21.5%
Percentage
10.2%
8.5%
8.7%
8.2%
8.4%
4.6%
3.7%
3.1%
2.3%
0.6%
0.3%
0.5%
0.6%
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Pre
Post
Giardia
Hookworm
Trichuris
Ascaris
Strongy -loides
Any helminth
Multiple helminths

55. To Review… General Truths about Nematodes
Polyparasitism
Burden greatest in children
except hookworm, ?Strongyloides
Don’t Multiply in Host (2 exceptions)
Eosinophilia = tissue invasion
Larval stages or Strongyloides

56. Recommended References
TROPICAL INFECTIOUS DISEASES
Principles, Pathogens, & Practice,
Second Edition, 2006
Guerrant, Walker, Weller
Churchill Livingstone
MANSON’S TROPICAL DISEASES
Twenty-first Edition, 2003
Cook & Zumla
W.B. Saunders
ATLAS OF TROPICAL MEDICINE & PARASITOLOGY
Sixth Edition, 2007
Peters & Pasvol
Mosby Elsevier
RED BOOK
2006 Report of the Committee on Infectious Diseases
Table Drugs for Parasitic Infections

57. Acknowledgements for Slides
Stephen Swanson, MD, DTM&H,
Hennepin County Medical Center, Minneapolis
Peter Hotez, MD, PhD, FAAP
President, Sabin Vaccine Institute
Microbiology, Immunol, & Tropical Medicine
The George Washington University School of Medicine

58. Post test with answers What is the most likely worm to be coughed or vomited up?
Trichuris
Hookworm
Strongyloides
Tapeworm
Ascaris

59. Which worm infection do you ALWAYS want to treat?
Ascaris
Trichuris
Strongyloides
Pinworm
Hookworm

60. Which worm’s burden of illness increases through your late childhood and early adulthood years?
Strongyloides
Hookworm
Ascaris
Trichuris
Pinworm

61. Which worm infection is most likely to mimic colitis?
Trichuris
Ascaris
Strongyloides
Pinworm
Hookworm

62. Which Nematode is the most likely to be the cause of eosinophilia in an immigrant/refugee from Africa who has been in America x 9 months?
Trichuris
Strongyloides
Pinworm
Hookworm
Ascaris

63. When is the ideal time to check Stool O & P in Returning Traveler?
IMMEDIATELY upon landing
Within 1 week
1 month
2 month
6 months
1 year