Antiparasitic Drugs II

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Antiparasitic Drugs II

• S Peder Cuneo
• Cuneo_at_u.arizona.edu

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Take Home From Monday

• Parasites are a serious health problem
• World/US
• Serious problem in developing nations
• Nonspecific clinical signs
• Lack of awareness of possible infections
• Lack of magic bullet must have Dx before using
  correct Tx

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Types of Parasites

• Helminthes
• Nematodes
• Roundworm, Pinworm, Whipworm, Pork Roundworm
• Filarial Nematodes
• Cestodes
• Beef, pork, fish tape worm, Common dog tape worm

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Treatment Need To Know

• Mebendazole
• Giant roundworm, Pinworm
• Thiabenzadole
• Encysted form of Pork roundworm
• Deithycarbamazine
• Filarial Nematodes
• Niclosamide
• Beef, pork and fish tape worms

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An Error From Monday

• Ivermectin is approved by FDA
• Strongyloidiasis
• Intestinal nematode
• Onchocerciasis
• River blindness

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Trematodes

• Flukes
• Have separate sexes
• All have development in snail host
• Blood flukes
• Schistosoma sp
• Liver flukes
• Fasciola sp
• Intestinal flukes
• Fasciolopsis

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Life cycle Blood Fluke
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Life cycle Liver Fluke
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Intestinal Fluke
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Treatment Cestodes (Tapeworms) and Flukes

• Niclosamide or Parziquantel
• Used to treat tapeworm infection
• Niclosamide kills head (scolex)
• Parziquantel
• Spastic paralysis causing detachment
• Parziquantel
• Used to fluke infections

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Drugs for Tapeworms and Flukes

• Niclosamide
• Very effective for all type of tapeworms
• Directly kills scolex (head) and proximal
  segments
• Praziquantel
• Effective for tapeworms
• Only drug for use for flukes

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Protozoa

• 65,000 Species of which 10,000 are parasitic
• Reproduction can be complex with asexual and
  sexual reproduction
• Infections can be direct or indirect
• For many infections treatment is not very
  effective

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Malaria Drugs

• Treatment of acute attack or clinical cure
• Prevention of relapse or radical cure
• Relapse only with P. vivax and P. ovale
• Clinical prophylaxis or suppressive therapy
• Must know if in Chloroquine sensitive or
  resistant area

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• Resistance of Plasmodium falciparum to
  choloroquine, the cheapest and the most used drug
  is spreading in almost all the endemic countries.
  Resistance to the combination of
  sulfadoxine-pyrimethamine which was already
  present in South America and in South-East Asia
  is now emerging in East Africa.

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Life cycle Amebiasis
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Treatment Amebiasis

• Asymptomatic/mild/moderate intestinal disease
• Iodoquinol
• Mechanism unknown
• Adverse reactions skin/nausea/fever/chills
• Sever intestinal/extra intestinal
• Metronidasole (Flagyl)
• Interacts with protozoa DNA causing strand
  breakage
• Convulsions, headache, numbness in extremities

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Giardiasis
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Leishmaniasis
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Leishmaniasis

• Worldwide
• 100 million humans
• Tropical and subtropical areas
• Three forms
• Cutaneous/Mucocutaneous/Visceral
• Untreated visceral form is often fatal

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Treatment Leishmaniasis

• Sodium Stibogluconate for all three forms
• Drug mechanism is unknown
• Generally well tolerated

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Toxoplasmosis

• Protozoa found in many animals
• Infection usually with undercooked meat and often
  asymptomatic but can led to encephalitis and
  death
• Congenital infections can cause brain damage,
  blindness or liver problems

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Toxoplasmosis (Protozoa)
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Treatment for Toxoplasmosis

• Pyrimethamine
• Inhibits production of folic acid needed for
  production of DNA/RNA and protein
• High dose will cause folic acid deficiency in
  host anemia/oral ulcers/diarrhea
• Sulfonamide added to potentate effect

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Trypanosomes

• African and American form
• African
• Sleeping sickness
• Vector is tsetse fly
• CS fever, lymphandenopathy, then mental dullness,
  in coordination, death
• Tx early (pre CNS) Suramin
• CNS Melarsoprol
• Both have serious side effects and poor treatment
  response

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American TrypanosomesChagas Disease

• South American, Caribbean
• Affects 10 million humans
• Infection
• Bite of blood sucking bug
• Transfusion
• Prenatal
• Chronic infections cause fatal heart damage
• Treatment
• Early Nifurtimox
• Chronic none

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Chagas Disease
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Ectoparasites

• Complex animals with separate sexes
• Inhabit our skin/hair
• Some but not all are species specific

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Treatment Ectoparasites

• Lindane
• Kills adults and ova
• Irritating to eyes and mucous membranes
• Caution with children and pregnant women
• Permethrin
• Causes paralysis in adult lice toxic to ova
• May cause skin irritation
• Crotamiton
• Kill mites and reduces itching
• Pyrethrins plus Piperonly Butoxide

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Ectoparasites Nuance or Vector?

• Fleas
• Dog tape worm
• Plague
• Murine Typhus (rat fleas)
• Lice
• Epidemic Typhus
• Mites (chiggers)
• Scrub Typhus

• Ticks
• Ehrlichiosis
• Lyme Disease
• Rocky Mountain spotted Fever
• STARI (Southern Tick Associated Rash Illness)
• Tick Typhus

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General Take Home Points

• Helminths
• Generally easier to treat
• Protozoa
• Harder to treat
• Generally cause more sever diseases
• No magic bullet you must ID before you can Tx!

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Things Not Mix Up

• Toxoplasmosis is a protozoa
• Toxocara is helminth/nematode
• You can get a tapeworm from your dog but you
  first must eat a flea
• Parasites you will without a doubt deal with
• Enterobiasis (Pinworm)
• Pediculosis (lice)

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REMEMBER IS IS A BUG EAT HUMAN WORLD OUT THERE
DONT BECOME THIS FELLOWS DINNER HAPPY TRAILS !!