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Drugs for HELMINTHIC INFECTION

Helminths consist of various species of parasitic worms. Unlike the single celled protozoa, helminthes have many cells, and thus their anatomy, physiology, and life cycleare more complex.

Classification of Helminthso Roundworms(nematodes)o Flukes(trematodes)o Tapeworm(cestodes)

Ascariasiso Caused by the roundworm Ascariasis Lumbricoideso The most common helminth disease worldwide affecting 1.4 billion people.The

parasite is endemic to latin America& Asia & 4 million American, generally inthe warm climates of the southeast, and in areas where hygiene and sanitation is

poor.o Occur most commonly in children between age 3 to 8 years old, since this group

is mostly likely exposed to contaminated soil without proper handwashingo Transmission of A. Lumbricoides occurs when a person accidentally ingest eggs

from the parasite. Once in the stomach, immature worm hatch from eggs, andlarvae attach to the intestinal wall. The larvae can travel through the vein andlymphatics and be carried to the lungs, where they burrow through the alveolar walls and migrate up to the bronchi. Once reaching the throat, the larvae areswallowed and the cycle begins again.

o A. lumbricoides develops into an adult worm in the intestine.Female adult wormlay as many as 240,000 eggs daily, which enter the feces.Under unsanitarycondition, ascaris eggs reach soil where they remain infective for years

o Ascariasis presents with both pulmonary and intestinal symptoms .o Pulmonary symptoms As the larvae reach the lung, the patient experiences

cough, dyspnea, & low grade fever. o The Intestinal phase is asymptomatic until large masses of worms are

present .o Diagnosis is through identification of eggs or worms in the feces .Occasionally, a

worm is observed passing through the anus, mouth or nose.o Oral Mebendazole(Vermox) for 3 days is the standard treatment. Stools are

rechecked 2 weeks after therapy. Albendazole & Pytanthel Pamoate arealternative medication.

Enterobiasiso Infection by pinworm Enterobius Vermiculariso most common helminth infection in the United Stateso The disease is caused by intense perineal itching due to the presence of deposited

Enterobius egg or migrating female worm. The itching is worse at night and maycause restless, enuresis and insomia

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o Diagnosis is by identification of eggs on the perianal skin or worms in the stool.o Transmission is by diapers, toys, hands, or food contaminated with the eggs.o Treatment: Mebendazole, Albendazole or Pyranthel. Single dose is sufficient to

eradicate the pinworm, although the dose maybe repeated in 2 weeks to maximizetherapeutic success.

Hookworm.o 2 Human hook worm: Ancylostoma duodenale & Necator Americanus.o Mouth part of hookworm are modified cutting plates that cause hemorrhage when

worm attaches to the intestinal mucosa to suck blood from the host . Children are particularly affected by the loss of blood . Although not directly fatal, hookworminfection can weaken the body by causing anemia, may cause death frominfection by opportunistic infection .

o Transmission: when infective larva penetrates the skin, often by a child walking barefoot through contaminated soil.

o Initial symptom of hook worm: itchy ground rash at the site of skin

penetration.As larvae migrate through the hosts blood, they travel the lung, andup the throat where they are swallowed and eventually end up in the smallintestine).

o Pulmonary symptoms include cough, blood tinge sputum.o Later symptoms include vague abdominal pain.

o Diagnosis: Infestation is confirmed by identification by hookworm eggs in thefeces.

o Larvae of dogs and cat hookworms can infect human, although they will notmature into adult worm in the human host. Transmitted to humans throughcontaminated soil or cat litter, these larvae remain in the skin where they migratefor many weeks and cause intense itching. This result in a condition known asLarva Migrans or Creeping eruption- Thiabendazole is a treatment of choice.

Tapeworm.o Beef tapeworm( Taenia Saginata) , grows 25 meters long. Pork tapeworm( Taenia

Solium) ,is 7 meters when raw or undercooked meat is eaten that contains cyst or larvae of the parasite

o Transmission: Acquired when raw or undercooked meat is eaten that contains cystor larvae of the parasites.

o Treatment of Choice for most tapeworm infection is a single dose of Praziquantel.For some infection, a laxative is given 2 hours after treatment. To remove all partsof the worm and its eggs.

Drugs for Helminths Infection or Antihelminthics. Drugs use to treat worm infection are called antihelminthics Pharmacotherapy is not indicated for all helminthic infections because some are

self-limiting and the adult parasites die out without reinfecting the host .

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When the infestation is severe or if complication is severe drug therapy isinitiated .

Complication cause by extensive infestation may include physical obstruction inthe intestine, malabsorption, extensive loss of blood, increased risk for opportunistic bacterial infections, and severe fatigue.

1.Mebendazoleo Mechanism of Action: Mebendazole kills helminths by Inhibition of glucose

transport and uncoupling energy metabolism in the parasite mitochondriao Route: Per Oral (PO)o Primary Metabolism: Hepatico Primary excretion: Feceso Pregnancy: Category Co Should be avoided during pregnancy, especially during the 1 st trimester .o Nursing Responsibility :

o Initiate infection control intervention to prevent spread of infection,including meticulous handwashing. Because helminthic infection are oftenresult of poor sanitation or unhealthy hygiene habits

o Treat all family members simultaneously, because pinworms aretransmitted from person to person .

o Discontinue the Drug if monitoring reveals elevated hepaticenzymes .Because the drug is metabolized in the liver

2. Albendazole- most common adverse effect: Abnormal liver function test).3. Thiabendazole4. Praziquantel- Drug of choice for schistosomiasis, a helminth infection cause by bloodflukes. People acquire the parasite by swimming in feces contaminated water.5.Pyranthel Pamoate6. Ivermectin- Drug of choice in treating Onchocerciasis or river blindness, adebilitating filarial infection in Africa, the Middle East and Latin America.