SOIL-TRANSMITTED HELMINTHIASIS
It is astonishing with how little reading a doctor can
practice medicine, but it is not
astonishing how badly he may do it (William Osler)
CLASSIFICATION
A. Morphology
–
Nematode ( Round worm )
–
Cestode ( Tape worm )
–
Trematode ( Flat worm )
B. Transmission
–
Soil-transmitted
–
Food and water borne
–
Insect and arthropod borne
C. Intermediate Host
–
1
–
2
–
3
D.
Location
–
Intestinal worm
–
Lung fluke
–
Blood fluke
–
Liver fluke
Nematode
- Enterobius vermicularis
- Trichuris trichiura
- Ascaris lumbricoides
- Hookworms ( Ankylostoma and Necator )
- Strongyloides stercoralis
- Trichinela spiralis
- Wuchereria bancrofti
- Brugia malayi
- Loa loa
- Oncocherca volvulus
- Dracunculus medinensis
- Toxocara canis aand cati
- Gnathostoma spinigerum
- Creeping eruption
Cestode
- Taenia solium
- Taenia saginata
- Hymenolepis nana
- Hymenolepis diminuta
- Diphyllobotrium latum
- Echinococcus granulosus
- Echinococcus multilocularis
Trematode
- Schistosoma
- Chlonorchis sinensis
- Opistorchis viverrini
- Fasciola hepatica
- Fasciolopsis buski
- Heterophyes heteerophyes
- Metagonimus yokogawai
- Paragonimus westermani
Soil-transmitted
- Ascaris lumbricoides
- Trichuris trichiura
- Necator americanus
- Ankylostoma duodenale
- Strongyloides stercoralis
EPIDEMIOLOGY - WORLD
- Ascaris : 1.5 billion
- Trichuris : 1.3 billion
- Hookworm : 0.9 billion
- Strongyloides : 70 millions ; in developed countries mostly found in HIV patients
- Ascaris and trichuris mostly in children
PATHOGENESIS
- Most of the time, from egg in the soil
- Some eggs on the leaves/vegetables
- Children play in the yard / soil without any hand/foot protection
- Eat raw vegetables
- Hookworms can penetrate the feet
- Strongyloides larvae – not egg – penetrate the feet also
- Egg will hatch in the GI tract
- Ascaris will reach mature stage in the GI tract. Sometimes it can migrate to the lung ( pneumonitis )
- Trichuris will stay in the gut
- Hookworms will stay in the gut. If the entrance is blood vessels ( foot penetration ), at the end it still will move to esophagus and GI tract
- Strongyloides larvae use the same pathway as the hookworms
CLINICAL MANIFESTATIONS
- Gut signs and symptoms ( nausea, pain, vomiting, diarrhea, obstruction, mass, bloating, malabsorption, bleeding )
- Anemia ; Growth and nutritional problems
- Prolaps recti ( trichuris )
- Obstruction of other organs ( trachea, bile duct )
- Pneumonitis ( ascaris, hookworms, strongyloides )
- Appendicitis, pancreatitis, peritonitis
- Local irritation
LABORATORY FEATURES
1.
Routine Blood Examination
–
Anemia
–
Eosinophilia
–
Growth parameter deficiency (
albumin, nutrients )
2.
Stool
–
Ova ( = egg ) à Egg per
gram ( epg )
–
Larva ( strongyloides, hookworms )
3.
Serology
Stool
- Kato – Katz
- Koga agar plate
- Baermann technique
DIAGNOSIS
- History ( pale, growth and development delay, parents found the worms, gastrointestinal symptoms, cough, living place )
- Physical examination – based on the history and possible clinical manifestations
- Laboratory ( blood, including serology, and stool ). If you can see the worm in the stool à must be very heavy infection
- Radiology, only if necessary
TREATMENT
- Anthelminthics
- Supportive treatment ( nutrition, including the nutrients )
- Symptomatic drugs ( fever, itch )
- Rarely need surgery
- Treat the whole family
TREATMENT - DEWORMING
- Ascaris is easy.
- Trichuris is more difficult than ascaris
- Hookworm is difficult and need longer time
- Strongyloides is very very difficult
- For nematode and cestode : mebendazole, albendazole, or thiabendazole can be used
- For trematode : praziquantel
- Other drugs : piperazine, pyrantel pamoat, ivermectin
- Ascaris : pyrantel pamoat will make the worms paralyzed and died; mebendazole can make the worms die and block the gut
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