Helminth

Ivermectin is the catalytic reduction product of avermectin, a macroHde containing a spiroketal ring system. Two other related antibiotics having significantly different stmctural features and biological properties, moxidectin and milbemycin oxime, were more recentiy introduced into the market. Although these compounds have no antimicrobial activity, they are sometimes referred to as antibiotics because they are derived from fermentation products and have very selective toxicities. They have potent activity against worms or helminths and certain ectoparasites such as mites and ticks. 

Antimony potassium tartrate (tartar emetic) has the advantage of being low in cost. It has been called the dmg of choice for Schistosoma japonicum infection (204) even though it fails to cure the disease in many patients. However, trivalent antimonials are no longer recommended for the treatment of helminthic infections because these compounds have an unacceptable toxicity and are too difficult to administer (205). 

Over the last several years, substantial progress in the discovery and development of anthelmintic dmgs has been made. Effective agents are available for most human gastrointestinal infections (Table 1) however, dmgs that are effective in treating the extraintestinal complications of many helminthic infections are still needed. 

Frequendy, the treatment of helminthic diseases requites adjunct medication. Allergic reactions are commonly seen as a result of tissue invasion by worms or as a consequence of anthelmintic therapy. Antihistamines and corticosteroids may be necessary adjuncts to therapy. Anemia, indigestion, and secondary bacterial infections can also occur and may requite concomitant therapy with hematopoietic drugs and appropriate antibiotics. 

Bithionol interferes with the neuromuscular physiology of helminths, impairs egg formation, and may cause defects in the protective cuticle covering the worm. At the biochemical level, the oxidative phosphorylation of the worm is inhibited. 

The final reduction product of pyrazine, piperazine (89), is a stable compound which behaves as a typical diamine. It has found extensive use in medicinal chemistry as a linking agent and as a medicine in its own right for the treatment of helminths both in human and veterinary medicine. 

Antiparasitic drugs are used for the treatment of parasitic infections caused by pathogenic protozoa or helminths (worms). 

Discuss the uses, general drug action, adverse effects, contraindications, precautions, and interactions of the drugs used in the treatment of helminth infections, malaria, and amebiasis. 

M parasite is an organism that lives in or on another organism (the host) without contributing to the survival or well-being of Hie host. Helminthiasis (invasion of Hie body by helminths [worms]), malaria (an infectious disease caused by a protozoan and transmitted to humans Hirough a bite from an infected mosquito), and amebiasis (invasion of Hie body by Hie amebaEntamoeba histolytica) are worldwide healfli problems caused by parasites. 

Pinworm is a helminHi infection that is universally common most oHier helminth infections are predomi-lianHy found in countries or areas of the world that lack proper sanitary facilities. Malaria is rare in the United States, but it is sometimes seen in individuals who have traveled to or lived in areas where this disease is a healtii problem. The first antimalarial drug, quinine, is derived from the bark of the cinchona tree. Amebiasis is seen Hiroughout the world, but it is less common in developed countries where sanitary facilities prevent Hie spread of the causative organism. 

The activity of pyrantel (Antimintii) is probably due to its ability to paralyze die helminth. Fbralysis causes die helminth to release its grip on die intestinal wall it is then excreted in die feces, pyrantel is used to treat round-worm and pinworm. Some patients receiving pyrantel may experience gastrointestinal side effects, such as nausea, vomiting, abdominal cramps, or diarrhea... 

The exact mechanism of action of thiabendazole (Mintezol) is unknown. This drug appears to suppress egg or larval production and tiierefore may interrupt die life cycle of the helminth. Thiabendazole is used to treat threadworm. Thiabendazole may cause hypersensitivity reactions, drowsiness, and dizziness. 

Unless ordered otherwise, the nurse should save all stools that are passed after the drug is given. It is important to visually inspect each stool for passage of the helminth. If stool specimens are to be saved for laboratory examination, the nurse follows hospital procedure for saving the stool and transporting it to the laboratory. If the patient is acutely ill or has a massive infection, it is important to monitor vital signs every 4 hours and measure and record fluid intake and output. The nurse observes the patient for adverse drug reactions, as well as severe episodes of diarrhea. It is important to notify the primary health care provider if these occur. 

Promoting an Optimal Response to Therapy The diagnosis of a helminth infection is made by examination of the stool for ova and all or part of the helminth. Several stool specimens may be necessary before the helminth is seen and identified. The patient history also may lead to a suspicion of a helminth infection, but some patients have no symptoms. 

Patients with massive helminth infections may or may not be acutely ill. The acutely ill patient requires hospitalization, but many individuals with helminth infections can be treated on an outpatient basis. 

The diagnosis of a helminth infection is often distressing to patients and their family. The nurse should allow time to explain the treatment and future preventive measures, as well as to allow the patient or family members to discuss their concerns or ask questions. 

Educating the Patient and Family When an anthelmintic is prescribed on an outpatient basis, the nurse gives the patient or a family member complete instructions about taking the drug, as well as household precautions that should be followed until the helminth is eliminated from the intestine The nurse develops a patient education plan to include the following... 

Follow the dosage schedule exactly as printed on the prescription container. (See Administering an Anthelmintic Drug for the directions specific for each drug.) It is absolutely necessary to follow the directions for taking the drug to eradicate the helminth. 

While he was living outside the country for 3 years, Mr. Evans became infected with a helminth. The parasite has been identified and the appropriate drug prescribed. Discuss the points you would include in a teaching plan for this patient. 

IgE Mediates immediate hypersensitivity by causing release of mediators from mast cells and basophils upon exposure to antigen (allergen). Defends against worm infections by causing release of enzymes from eosinophils. Does not fix complement. Main host defense against helminthic infections. 

Space constraints do not allow detailed discussions of the world of parasites, and clinicians and students are directed to some excellent resources for further details on parasites and parasitic diseases.1,2 Discussion in this chapter will include those parasitic diseases that are more likely to be seen in the United States and will include gastrointestinal parasites (primarily giardiasis and amebiasis), protozoan infections (malaria and South American trypanosomiasis), some common helminthic... 

Enterobiasis, or pinworm infection, is caused by Enterobius vermicularis. It is the most widely distributed helminthic infection in the world. There are approximately 42 million cases in the United States, primarily affecting children. The most common manifestation of the infection is cutaneous irritation... 

Morbidity and disease due to helminthic infections is related to the intensity of infection. The major adverse effects of helminthic infections are malnutrition, fatigue, and diminished... 

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