2. INTRODUCTION
Humans are the primary hosts for the most of helminthic
infections.
Most worms produce in human sexually by producing
eggs and larvae
These pass out of body and infect the secondary host
Imature forms invade humans via skin or GIT and mature
to adult worms with characteristic tissue distribution.
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3. Types (clinical)
1. Worms live in hosts alimentary canal.
2. Worms or larvae live in other tissues of host
body like muscles , viscera , meninges ,
lungs, subcutaneous tissues.
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10. 1. Alimentary canal(intestinal tape worms)
B)TAPE WORMS (CESTODES)
Taenia saginata(Beaf) ,
Taenia solium(Pork),Hymenolepis nana(Dwarf)
,diphylobothrium latum(Fish)
Humans become infected by eating raw or under
cooked meat containing larvae of infected cattle or pig
which has encysted in the animal muscle tissue.
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11. Cestodes con’d
In some conditions this larvae may develop in
humans resulting cysticercosis (i.e. larvae gets
encysted in the muscle and viscera or more
seriously in the brain or eye.)
In case of H.nana both adult worm and larvae can
be present in the same host.
In case of D.latum infections occurs by eating raw
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or undercooked fish
14. 2. TISSUE WORMS
A.TREMATODES(Schisotomes)OR
FLUKES(leaf like)
Schistosoma haematobium
Schistosoma Japonicum
Schistosoma mansoni
(These cause SCHISTASOMIASIS) also called
(BILHARZIA) means disease of blood vessels.
Adult worms of both sex live and mate in veins or venules
of the gut wall or the bladder, eggs pass into the bladder
or gut and produce inflammation of these organs ,
resulting in haematuria or loss of blood in feces.
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15. Tremtodes (flukes) con’d
Eggs hatch in water and develop in to miracidia(1st stage of
larva of trematode and further develop in the body of snail),
which enter to 2ndry host a particular species of snail ,where it
develops to free swimming cercarae (final free-swimming stage
of a trematode),These infect humans by penetrating to skin
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16. Paragonimus westermani (lung fluke)
disease is caused by eating raw crab or fish , larvae
move from intestine to blood and settle in lungs
Clonorchis sinensis(liver fluke)
disease is caused by eating raw fish and worm
settle in the biliary tract
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17. Tissue worms cont’d
B. TISSUE ROUND WORMS
Trichnella spiralis.
Dracunulus medinensis (guinea worm)larva migrate
from intestine to tissue of leg or foot and protrude out by
making ulcer
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18. FILARIAE includes
Wuchereria bancrofti
Loa loa
Onchocerera volvulus
Brugia malayi
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22. Filariae: Wucheria bancrofti ,loa loa , onchocera
volvulus and Brugia malayi
Adult filariae live in the lymphatics,and cause
lymphadenitis and swelling of limb. connective
tissue or mesentery of host and produce live
embryos or microfilariae, which goes to blood
stream.
They are ingested by mosquitoes or similar insects,
they develop to larvae in 2ndry host and pass to
mouth parts of insect and
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re-injected to humans
23. C. Hydatid tape worm
Echinococcus species .
These are cestodes ,primary in canines (dogs) and
sheep as intermediate host.
humans can act intermediate host in which larvae
develop to hydatid cyst with in tissue.
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30. ANTHELMINTIC DRUGS
BENZIMIDAZOLES
1.ALBENDAZOLE:
It is a broad spectrum
It is a drug of choice (primary therapeutic
application) for treatment of hydatid disease and
cystecercosis, it is also used for the treatment of
(intestinal nematodes) pinworm, hookworm
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31. Albendazole con;d
Mechanism of action:
It inhibits microtubule synthesis in
nematodes(intestinal round worms) that
irreversibly impairs glucose uptake, intestinal
parasites are immobilized and die slowly.
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32. Pharmacokinetics (Albendazole)
It is benzimidazole carbamate
it is adminstered orally , and absorbed erratically
(unpredictable) , absorption can be increased with
fatty meal
It is metabolized in the liver rapidly to active
metabolite albendazole sulphoxide
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33. Pharmacokinetics (Albendazole)
It has a plasma half life of 8-12 hours
Sulphoxide is mostly protein bound ,
distributes well to tissues and enters bile, csf.
Metabolites are excreted in urine
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34. Clinical uses (albendazole)
used on empty stomach when used against
intraluminal parasites but with fatty meal when
against tissue parasites.
In hookworm, pin worm infection : children under
2 years 400 mg orally as a single dose repeated
after 2-3 wks for pin worm
2. Hydated diseases:
drug of choice ,400 mg twice with meals for 1
month or longer.
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35. Albendazole con’d
3. Neurocysticercosis:
It is controversial as it has not proved superior to
corticosteroid alone.
It is used along with cotricosteroid to decrease the
inflammation caused by dying organism and it also
reduces the duration of course i.e. 400 mg twice daily for
21 days
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36. Albendazole con’d
Adverse effects:
In short term: use no significant adverse effects.
In long term use : as used in abdominal distress,
headache ,fever , fatigue, alopecia , increased liver
enzymes , pancytopenia. Blood counts and LFT should be
followed.
Not given during pregnancy and in hypersensitive
people.
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37. MEBENDAZOLE(Vermox)
it is a synthetic benzimidazole
it has wider spectrum and is more safer than albendazole
Mechanism of action:
It inhibits microtubule synthesis in nematodes that
irreversibly impairs glucose uptake.Intestinal parasites are
immobilized and die slowy.
It kills hook worm, pin worm , ascariasis and trichuris eggs.
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38. Mebendazole con’t
Pharmacokinetics:
less than 10% of orally administered drug is absorbed
Absorption increases with fatty meal.
Absorbed drug is 90 % protein bound
It is converted to inactive metabolites rapidly in liver.
It has half life of 2-6 hours
It is primarily excreted in urine.
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39. Mebendazole con’t
Clinical uses:
It is taken orally before or after meal tablets should be chewed
before swallowing.
Pinworm infection: 100 mg as a single dose, to be repeated after
2-3 weeks.
in adults and children over 2 years cure rate is 90-100 % except
hook worm but there occurs marked reduction
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40. Mebendazole con’d
Intestinal cappilliaris: 400 mg /day in divided
doses for 21 day or more.
Trichinosis :it has limited efficacy against adult
worm.200-300 mg for 3 days ,then 400-500 mg for
10 days with fatty meal and co-administration with
corticosteroids in sever infection
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41. Mebendazole con’d
Adverse effects and precautions:
No adverse effects in short term therapy.Mild GI disturbance.
With high dose Hypersensitivity reactions,agranulocytosis , alopecia
,elevation of liver enzymes .
used with caution under 2ys of age may cause convulsion in this
group.
enzyme inducers and inhibitors affect plasma level of the drug.
hepatic parenchymal disease 41
42. Thiabendazole
it is benzimidazole
it is chelating agent and form stable complexes with metals
including iron, but does not bind with calcium.
it is rapidly absorbed
it has half life of 1.2 hrs
It is completely metabolized in liver and 90% is excreted in urine
it can also get absorbed through skin
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43. Thiabendazole con’d:
mechanism of action: similar to other benzimidazoles.It is ovicidal
for some paracites
clinical uses:
should be given after meals .and tablets should be chewed
for thread worms infections: 25 mg /kg ( not more than 1.5 grams)
twice daily for 2 days ,can be repeated after 2 week. In hyper infection
syndrome drug is continued twice daily for 5-7 days.
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44. Thiabendazole con’d
adverse reactions and contraindications:
It is more toxic than other benzamidazoles
GI disturbances
Pruritus ,headache, drowsiness , psychoneurotic symptoms.
Irreversible liver failure.
Fatal Steven –Johnson syndrome(inflammation of skin)
Not used in children below 15 kg weight. pregnancy, hepatic and renal
diseases.
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45. PYRANTEL PAMOATE
It is a broad specturm anthelmintic
but it is not effective against tricuriasis(whip worms), and
trichostrongylus orientalis infections. Oxalate pamoate is effective
Pharmacokinetics:
It is poorly absorbed orally ,
Half of the drug is excreted unchanged in the feces.
Mechanism of action:
It is a depolrazing neuromuscular blocking agent that causes
release of acetylcholine and inhibition of cholinestrase leads to
paralizes of worms.
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46. Pyrantel pamoate con’d
Efficacy and clinical uses:
it is very effective against luminal organisms.
It is not effective against migratory stages in the tissues or
against ova
pin worm: 11 mg /kg as a single dose to be repeated in 2
wks.
common round worm: single dose to be repeated after
2wks
hook worm: single dose for light infection but a 3 days
course is necessary for heavy infection.especially N
amerianus. 46
47. Pyrental pamoate con’d
Adverse Effects .
Infrequent mild transient GI disturbance
drowsiness , headache ,insomnia.
Rash ,fever
Contraindciations
Should not be used in liver diseases.
Pregnancy
and child under 2 years of age
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48. PIPERAZINE
Only recommended for the treatment of
ascariasis.
it is absorbed orally and excreted in urine
Mechanism of action:
it causes paralysis of ascaris by blocking
acetylcholine at myoneural junction ,expelling the
live worm by normal peristalsis.
Not recommended for other helminth infections
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49. Piperazine con’d
pharmacokinetics :
it is readily absorbed orally and excreted
unchanged in urine.
75 mg /kg/day for 2 days once daily
treatment is continued for 3-4 days or
repeated after one week in case of heavy
infections.
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51. NICLOSAMIDE
It is a useful drug for treatment of tape worm
(cestodes)infestation
Mechanism of action:
Adult worm is rapidly killed by inhibition of oxidative
phosphorylation or stimulation of ATPase activity.
Pharmacokinetics:
It is poorly absorbed from gut
Neither drug nor its metabolites are found in blood or
urine
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52. Niclosamide con’d
Clinical uses:
Beef tape worm, pork tape worm, fish tape worm.
2 gram of single dose is given in the morning on
the empty stomach.
not effective against cysticercosis or hydatic
disease.
Hymenolepis nana: It is effective against adult
parasite
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53. Niclosamide con’d
Adverse effects:
Mild ,infrequent and transitory GI
disturbance
Alcohol consumption should be
avoided
not indicated in children under 2
years of age.
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54. DIETHYLCARBAMAZINE
Is a drug of choice for the treatment of filariasis and
tropical eosinophillia.
Pharmacokinetics:
It is synthetic peprazine derivative
Rapidly absorbed from gut
It has a half life of 2-3 hours which increases in
alkaline urine to 10 hours.
It is excreted in urine unchanged.
dosage is reduced in urinary alkalosis and renal
impairment.
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55. DIETHYLCARBAMAZINE con’d
Mechanism of action:
It immobilizes microfilariae and alters its surface
structure ,making them susceptible to destruction by
host defense mechanis
It is not teratogenic
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56. DIETHYLCARBAMAZINE con’d
It is a drug of choice for the treatment of W.bancrofti,
B.malayi,B.timori, loa loa
Microfiliariae are rapidly killed .adult worms are killed
slowly requiring several course of treatment
It is highly effective against L.loa. for these infections the
dose is 2mg/kg three times a day for 2-3 weeks.
for W.bancrofti infections to reduce the incidence of
allergic reactions to dying microfilariae a single dose is
administered on the first day , two doses on the second day
and three doses on the 3rd day. 56
57. DIETHYLCARBAMAZINE con’d
For loa ( with risk of encephalopathy) or B.malayi infections
,individual
doses should start at 1 mg /kg once on the first day and gradually
increased over 5-6 days
Anti histamines and corticosteroids are given in allergic
manifestations.
Complete Cure may be require several courses of treatment over 1-2
years.
The drug may be used in prohylaxis
300 mg weekly or 300 mg on 3 successive day each month for
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loiasis.
60. IVERMECTIN
It is drug of choice for treatment of filaria and
onchoceriais,elephantiasis
it is a macrocyclic lactone
It is used orally and is rapidly absorbed, posses
wide volume of distribution.
It has a half life of 16 hrs
It is exclusively excreted in urine
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61. IVERMECTIN con’d
Mechanism of action:61
it intensifies GABA –mediated transmission of
singals in peripheral neverse
In onchoceriasis it is microfilaricidal
It does not kill adult worm
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62. IVERMECTIN con’d
Clinical uses:
Onchoceriasis: a single dose of 150 mg/kg with
water on empty stomach,repeated after every 3
months for one year,after this it is repeated
yearly untill adult worm dies which may take a
year or more
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63. IVERMECTIN con’d
Strongyloidiasis: 200mg for 2 days in
immunosuppresed patient ,repeated treatment is
often needed.
Bancrofti filaricidal: as it is mirofilaricidal
It is also used for scabies and cutaneous larva
migrains.
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64. IVERMECTIN con’d
Adverse effects:
Fatigue ,dizziness, GI disturbance
In onchoceriasis:
Mazotti reaction i.e. fever, headache, dizziness,
somonlence, weekness, rash ,diarrhea, arthralagia,
hypotension, lymphadenitis, peripheral edema due to
killing of microfiliariae, for this steroids may be
necessary for several days
Swelling and abscess at site of adult worm
Punctuate corneal opacities.
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65. IVERMECTIN con’d
Contraindication: other drugs that enhance
GABA
e.g Barbiturates, bnezodiazepines, valproaic acid.
pregnancy
Imparied blood brain barrier
Children under 5 years of age.
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66. BITHIONOL
it is drug of choice for the treatment of
fasioliasis ( sheep liver fluke)
It is also alternative drug for pulmonary
paragonimiasis
Pharmacokinetics:
It is orally administered and excreted in urine.
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67. BITHIONOL
Clinical uses:
30-50 mg /kg in 2-3 divided doses administered orally
after meals on alternate day for 10 – 15 days.
Adverse effects:
GI disturbance
Dizziness,headache
Pruriuts ,urticaria,Leucopenia
Contraindications and precautions:
hepatitis ,leucopenia
Used with caution under 8 years of age.
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