Nematodes

1
Nematodes

• Gregory L. Brower, D.V.M., Ph.D.
• Cell Biology and Anatomy
• School of Medicine
• Columbia, South Carolina

2
Parasitology Resources

• World Health Organization
• http//www.who.int/en/
• Center For Disease Control
• http//www.cdc.gov/

http//www.cdfound.to.it/html/atlas.htm
3
At Risk Populations

• Developing countries
• Tropics
• Southern United States
• Institutional settings (e.g. daycares)
• Newly arrived persons
• Travelers
• Immigrants
• Refugees

4
Helminthic Parasites of Man Round Worms
(Nematodes)
5
Incidence of Parasitism
6
Incidence of Parasitic Worm Infections in South
Carolina
7
One Worm Means Many Worms
8
Nematodes Relative Size
9
Ascariasis Geographical Distribution
10
Ascaris lumbricoides Morphology
11
Ascaris lumbricoides Life Cycle
12
Symptoms of Ascariasis
13
AscariasisExtended Abdomen
14
AscariasisIntestinal Rupture
15
AscariasisDiagnosis
characteristic corticoid eggs in the stool
16
AscariasisPrevention and Treatment

• Good hygiene
• Mebendazole

17
Trichinosis Geographical distribution

• World-wide distribution
• Related to
• Hog farming conditions
• Pork consumption

18
Trichinosis Incidence in the US
19
Trichinosis Case-1

• A 54 year old man who resided in Franklin County.
  The patient had been hospitalized a 3-week
  history of diaphoresis, fever, weakness,
  tachycardia, diarrhea, an 8-pound weight loss,
  and dry cough. Laboratory testing indicated an
  elevated white blood cell (WBC) count (20,600/mm3
  with 33 eosinophils), hyponatremia), elevated
  lactate dehydrogenase and elevated creatinine
  phosphokinase.
• The patient reported eating 2 pounds of nearly
  raw bear meat during several meals 2 weeks
  earlier. Because of suspicion of trichinellosis,
  albendazole and corticosteroids were administered
  and the patient recovered fully by February 2004.
  

20
Trichinosis Case-2

• 38 year old man and a woman aged 54 years were
  admitted to a hospital with 7- and 14-day
  histories , respectively, of fever, chills,
  headache, myalgias, arthralgias, and facial
  swelling.
• The man's WBC count was 14,600/mm3, with 24
  eosinophils, 13 lymphocytes, and 2 monocytes.
• The woman's WBC count was 16,200/mm3, with 28
  eosinophils, 13 lymphocytes, and 3 monocytes.
• Serum obtained from both patients tested positive
  for Trichinella antibodies.
• Both were started on a course of albendazole and
  corticosteroids and recovered fully.

21
Trichinosis Case-2
Questioning of the patients revealed that the man
had shot a black bear in Canada. The bear was
field dressed, and selected meat was packed on
ice for transport to Tennessee. The wife prepared
and cooked the bear meat on an outdoor grill for
themselves and four other persons. The man and
woman ate their steaks medium rare while the
other four ate their steaks well done. The meat
was examine histologically and numerous
Trichinella larvae were observed encysted in
characteristic hyalinized capsules in the
striated muscle tissue.
22
Trichinella spiralis Morphology
23
Trichinella spiralis Life Cycle
24
TrichinosisSymptoms
25
Trichinosis Diagnosis

• Symptoms
• Recent history of eating under-cooked pork
• Eosinophilia
• Increased serum creatinine phosphate and lactate
  dehydrogenase
• Serology

26
Trichinosis Treatment and Prevention

• Treatment
• Corticosteroids for symptomatic relief
• Mebendazole for killing parasite

• Prevention
• Elimination of parasite from hogs
• Cooking meat well

27
TrichuriasisEpidemiology

• A tropical disease, primarily of children
• 65 of half million cases seen in Asia and Africa
• Seen is rural (low country) South Carolina
• Caused by Trichura trichuris (whipworm)

28
Trichura trichurisLife Cycle
29
Trichura trichurisSymptoms

• Abdominal pain
• Chronic profuse diarrhea with mucus and blood
• Weight loss and anemia
• Prolapsed rectum

30
Trichura trichurisheavy infection
31
Trichura trichurisDiagnosis

• Symptoms
• Examine stool for eggs

32
Trichura trichurisPrevention and Treatment

• Sanitary eating habits and improved hygiene are
  preventive
• Mebendazole is effective

33
PinwormEpidemiology

• World-wide, primarily in children
• Urban disease in crowded environment
• Enterobius vermicularis

34
Enterobius vermicularis Life Cycle
35
Enterobius vermicularis Symptoms

• Perianal, perineal and vaginal irritation
• Insomnia and restlessness
• Occasionally mild abdominal pain, nausea and
  vomiting

36
Enterobius vermicularis Pinworm Neurosis

• The conscientious housewifes mental distress,
  guilt complex, and desire to conceal the
  infection from her mother-in-law is perhaps the
  most significant trauma caused by this
  persistent, pruritic parasite.

37
Enterobius vermicularis Diagnosis

• Nocturnal observation

38
Enterobius vermicularis Diagnosis

• Scotch tape test
• for eggs

39
Enterobius vermicularis Diagnosis

• Scotch tape test
• for eggs

40
Enterobius vermicularis Diagnosis

• Scotch tape test
• for eggs

41
Enterobius vermicularis Prevention and Treatment

• Improved hygiene is preventive
• Pyrantel palmoate is very effective
• Mebendazole is an alternative

42
Strongyloides stercoralis Epidemiology

• Prevalent in the tropics
• Southern US and Puerto Rico

43
Strongyloides stercoralis Morphology
44
Strongyloides stercoralis Life Cycle
45
Strongyloides stercoralis Symptoms
46
Strongyloides stercoralis Enteric Disease

• Enteritis
• Catarrhal enteritis
• Edematous enteritis
• Lymphatic obstruction
• Ulcerative enteritis
• Auto-Infection of L1 larvae
• Disseminated strongyloidiasis
• Hyperinfective syndrome
• Immuno-compromised patients
• HTLV-1
• Human T-cell Lymphotropic Virus 1

47
Strongyloides stercoralis Diagnosis

• Larvae in stool

48
Strongyloides stercoralis Prevention and
Treatment

• Improved hygiene is preventive
• Ivermectin or Mebendazole

49
HookwormEpidemiology
50
Hookworm Morphology
51
Hookworm Morphology
52
Hookworm Life Cycle
53
Hookworm Symptoms
54
Hookworm Ground Itch
55
Hookworm Anemia and Edema
56
Hookworm Diagnosis

• Eggs in stool

57
Hookworm Prevention and Treatment

• Sanitation
• Mebendazole is effective

58
Dracunculus medinensisEpidemiology

• Guinea worm
• Fiery serpent of Israel
• Dracunculosis
• 3-5 million infected

59
Dracunculus medinensis Morphology

• Larva 600 m
• Adult 50-120 cm
• 3-5 million infected

60
Dracunculus medinensis Life Cycle
61
Dracunculus medinensis Mode of Infection
62
Dracunculus medinensis Symptoms

• Blistering in the skin
• Abscesses in other tissues
• (from dying adult)
• Secondary infections

63
Dracunculus medinensis Symptoms
64
Dracunculus medinensis Symptoms
65
Dracunculus medinensis Symptoms
66
Dracunculus medinensisTreatment and Prevention

• Mebendazole is effective
• Worm must be extracted slowly, few cm a day
• Water treatment

67
Blood and Tissue Helminths

• Wuchereria bancrofti
• Wuchereria (Brugia) malayi
• (elephantiasis)
• Onchocerca volvulus
• Loa loa
• (blindness)

68
ElephantiasisGeographic Distribution
69
Wuchereria Morphology
10 cm
250 m
70
Wuchereria Life Cycle
71
Wuchereria Elephantiasis
72
Wuchereria Scrotal Involvement
73
Wuchereria Diagnosis

• History
• Symptoms
• Microfilaria in blood

74
Wuchereria Prevention and Treatment

• Avoid mosquitoes in endemic areas
• Diethyl carbamazine kills adult worm and
  sterilizes the female
• Steroids
• Surgery
• Cooler climate reduces symptoms

75
Onchocerca volvulus

• Onchocerciasis is the major cause of blindness in
  some parts of Africa
• It is also known as river blindness

76
Onchocerca volvulusGeographic Distribution
77
Onchocerca volvulus Morphology
78
Onchocerca volvulus Life Cycle
Black fly Simulium damnosum
79
Onchocerca volvulus Skin Nodules
80
Onchocerca volvulus Progressive Keratitis
81
Onchocerca volvulus Diagnosis

• History
• Symptoms
• Microfilaria in nodules

82
Onchocerca volvulus Prevention and Treatment

• Avoid black flies in endemic areas
• Diethyl carbamazine kills larvae
• Suramin is effective against adult worms

83
Loa loa

• Loasis is similar to onchocercaisis
• It can also cause blindness

84
Loa loa Geographic Distribution
85
Loa loa Morphology
86
Loa loa Life Cycle
Deer fly Chrysops
87
Loa loa Calabar Swelling
A transient subcutaneous swelling marking the
migratory course through the tissues of the adult
filarial eye worm that appear most frequently on
the back of the hand or on the arm.
88
Loa loa Progressive Keratitis
89
Loa loa Diagnosis

• History
• Symptoms
• Microfilaria recovered from blood or conjunctiva

90
Loa loa Prevention and Treatment

• Avoid deer flies in endemic areas
• Diethyl carbamazine kills larvae
• Suramin is effective against adult worms

91
Toxocara canisToxocara catti

• Roundworms of dogs and cats
• Infection occurs when egg from animal feces is
  swallowed
• Larvae migrate to visceral organs and produce
  inflammatory reactions
• Can cause blindness

92
Toxocara canis Transmission
93
Toxocara canis Incidence

• 14 of US population
• Most prevalent in youth under 20.
• Visceral larva migrans
• Commonly asymptomatic

94
Toxocara canis Ocular Larva Migrans
DDX Retinoblastoma, Baylisascaris procyonis, Loa
loa
95
Visceral Larva Migrans DDX, Prevention and
Treatment
DDX Eosinophilic meningoencephalitis caused by
the raccoon ascarid Baylisascaris procyonis.

• Avoid orofecal contact with cats and dogs
• Mebendazole is effective
• Prednisone

96
Ancylostoma braziliensis Ancylostoma caninum

• Hookworms of dogs
• Infection occurs when egg from animal feces is
  swallowed
• Larvae migrate in the skin and produce
  inflammatory tracks
• Can cause blindness

97
Cutaneous Larva MigransAncylostoma braziliensis,
Ancylostoma caninum, etc.
Migrating larva cause serpiginous pruritic tracts
in subcutaneous tissue.
98
Cutaneous Larva Migrans
Creeping linear red rash caused by burrowing
hookworm larvae.
99
Cutaneous Larva Migrans Prevention and Treatment
DDX Depiction of inflammatory breast cancer of
the left breast showing peau d'orange and
inverted nipple.

• Avoid orofecal contact with dogs
• Mebendazole is effective
• Prednisone

100
PULMONARY DIROFILARIASIS PRESENTING AS MULTIPLE
PULMONARY NODULES
Breast Biopsy CDC
Lung biopsy revealed extensive caseating
granulomas with necrotic areas ringed by
palisaded histiocytes and scattered
multinucleated giant cells. There were many
scattered fragments of partially calcified
material with a structural morphology consistent
with decaying fragments of Dirofilaria immitis
(Canine heartworm).