Parasites tapeworm

Niclosamide [50-65-7] (2/5-dichloro-4 -nitrosahcylanihde) has been commonly used against tapeworms in small animals (5). Although tapeworms (cestodes) are frequently refractory to anthelmintics highly active against other intestinal parasites, they are sensitive to niclosamide as well as pra2iquantel [55268-74-1] and epsirantel. Pyrantel pamoate [22204-24-6] is probably the most common animal wormer used in the 1990s. 

Both the adult and the larval cysticerci (bladderworm) of Taenia solium (pork tapeworm) are able to Hve in humans the parasite is found sporadically in uncooked pork. In the stomach, the larva is digested out of the pork flesh it then grows and attaches to the wall of the small intestine. Maturity is reached in 5—12 weeks. The adult is 5 m long, and untreated adult worms may survive for 25 years. 

The modes of action for niclosamide are interference with respiration and blockade of glucose uptake. It uncouples oxidative phosphorylation in both mammalian and taenioid mitochondria (22,23), inhibiting the anaerobic incorporation of inorganic phosphate into adenosine triphosphate (ATP). Tapeworms are very sensitive to niclosamide because they depend on the anaerobic metaboHsm of carbohydrates as their major source of energy. Niclosamide has selective toxicity for the parasites as compared with the host because Httle niclosamide is absorbed from the gastrointestinal tract. Adverse effects are uncommon, except for occasional gastrointestinal upset. 

Niclosamide causes the tapeworm head to disengage from the intestinal wall of the host and the body wall of the parasite to disintegrate. The first... 

Ivermectin is active against two significant phyla of animal parasite the Nemathehninthes or nematodes (roundworms) and the Arthropoda (insects, ticks, and mites). Ivermectin is inactive against platyhehninthes (flukes and tapeworms). 

Ivermectin is used in cattle, sheep and horses at 0.2 mg/kg swine at 0.3 mg/kg dogs at 0.006 mg/kg and man at 0.05 —0.2 mg/kg. It is effective against parasitic nematodes, gmbs, Hce, mites, ticks, and bots. Ivermectin is not active against tapeworms, flatworms, bacteria, or fungi. 

Albendazole (Albenza) interferes wiHi Hie synHiesis of the parasite s microtubules, resulting in deatii of susceptible larva This drug is used to treat larval forms of pork tapeworm and to treat liver, lung, and peritoneum disease caused by the dog tapeworm. 

Specimens should be examined grossly to determine the consistency (hard, formed, loose, or watery), color, and presence of gross abnormalities such as worms, mucus, pus, or blood. It may be profitable to examine flecks of mucus, pus, or blood for parasites. If adult worms or portions of tapeworms are sought, the feces may be carefully washed through a screen. (Small worms may be difficult to see if gauze is used.) The identification characteristics of adult worms are not discussed in this chapter, so parasitology books should be consulted. 

Adult worms, or objects suspected to be adult worms, may be submitted to the laboratory. The laboratory must determine if these are helminths and, if so, if they are parasites. Identification characteristics are described in standard references. Tapeworm proglottids, particularly those of the Taenia species, are difficult to differentiate grossly unless they are cleared so that the internal structure can be seen and the number of lateral uterine branches can be counted. One procedure for clearing the proglottids is outlined below. 

Tapeworm. A parasitic intestinal cestode worm having a flattened, band-like form. The eggs of tapeworms are ingested by the intermediate host, they produce the larval stage in tissues. When the flesh of intermediate host is eaten, the larvae develop within the alimentary canal of the definitive host into adult tapeworms. 

Although relatively high doses (4 6 kGy) are required to kill food-borne parasites, much lower doses are adequate to prevent their reproduction and maturation resulting in loss of infectivity. Table 6 summarizes the effect of ionizing radiation on the most important parasites that may be associated with fishery products and meats [38]. Thus the parasitic roundworm Trichinella spiralis, which causes trichinosis, the pork and beef tapeworms, the protozoon in pork responsible for toxoplasmois, and various flukes that infest fish, can be rendered noninfective by low-dose radiation treatment. Doses of... 

Niclosamide (9.122), a salicylamide derivative, is the drug of choice for most tapeworm infestations. Niclosamide inhibits oxidative phosphorylation within the parasite, causing the cestode to be rapidly killed. 

Epidemics are most likely to occur when the climate provides the optimum combination of temperature and humidity or when animals are kept under crowded, damp conditions. The impact of a parasitic infection varies considerably according to the species of the worm involved. Adult tapeworms are relatively harmless, but certain blood- or tissue-feeding species of nematodes are highly pathogenic. More often than not, however, it is the invasion of the larvae rather than the adult parasites that is responsible for outbreaks of clinical disease. 

Many parasitic flatworms (tapeworms and flukes) attack higher organisms.124 Among them are the Schistosoma, tiny worms that are transmitted to humans through snails and which attack the blood vessels. The resulting schistosomiasis is one of the most widespread debilitating diseases on earth today, affecting 200 million people or more.125126... 

As parasites, flatworms have extended their global presence by taking advantage of the adaptations of many diverse invertebrate and vertebrate hosts. Many parasitic forms are host-specific and many of these are site-specific within or on their host. Contemplate on the biodiversity of vertebrates, consider that many platyhelminths use one or more intermediate hosts and one may just begin to grasp the diversity of parasitic flatworms. From the microscopic interstitial free-living species that live between particles of mud to the enormously long tapeworms of blue whales, an estimate of 100,000 extant species, of which only about 20,000 have been formally... 

Because of their significance for human or animal health, cestode worms have been intensively studied. The complexity of the host-parasite interaction, however, makes it difficult to investigate factors that regulate the differentiation of specific life stages. To overcome this problem, protocols have been developed to easily maintain tapeworms in the laboratory. 

Desowitz, M. (1981) Harmonious Parasites. In Desowitz, M. (ed.) New Guinea Tapeworms and Jewish Grandmothers. Pickwick, London, pp. 179-205. 

Taeniid cestodes have a prey-predator life cycle involving two mammalian hosts. The definitive host is a carnivore or omnivore, which harbours the adult tapeworm parasite in the small intestine. Mature infective eggs are released with the faeces and, when these are ingested by a suitable species of intermediate host, the oncosphere contained within the egg is liberated through the influence of intestinal secretions, particularly bile. The activated parasite penetrates the mucosa of the small intestine... 

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