Arthropod ectoparasites

Adverse hygienic conditions favor human infestation with multicellular organisms (referred to here as parasites). Skin and hair are colonization sites for arthropod ectoparasites, such as insects (lice, fleas) and arachnids (mites). Against these, insecticidal or arachnici-dal agents, respectively, can be used. Endoparasites invade the intestines or even internal organs, and are mostly members of the phyla of flatworms and roundworms. They are combated with anthelmintics. 

Macrocyclic lactones are active against a variety of nematodes but lack activity toward cestodes and trematodes. They are also active against a wide variety of insects and other arthropods, including mites, ticks, and lice. Since these compounds encompass activity against both endo- and ectoparasites, they are also called ectendocides. 

Ivermectin is exceptionally effective in very low dosages against nematodes and arthropod parasites in cattle and has been widely used for treatment of endo-and ectoparasites in cattle, sheep, goats, and swine (49). It is administered orally, parenterally, or as a pour-on preparation at dosages ranging from 0.2 to 0.6 mg/ kg bw. Ivermectin exhibits teratogenic effects in rat, rabbit, and mouse. 

Ivermectin is a semisynthetic analog of avermectin B which contains at least 80% of 22,23-dihydroavermectin B,a and not more than 20% of 22,23-dihydroavermectin B,b. It is a potent anthelminthic/insecticide for the control of a wide variety of arthropod parasites, including endoparasites and ectoparasites of animals such as cattle, horses, sheep, swine, and dogs. Its oral LD50 in rats is 650 mg/kg. 

Khokhlova, I.S., Vinarski, M. et al. (2008). Geographical patterns of abundance testing expectations of the abundance optimum model in two taxa of ectoparasitic arthropods. Journal of Biogeography 35, 2187-2194. 

The rjq)id advances in immunobiology, vector biology, genomics, proteomics, and vaccine technology make it very likely that anti-arthropod and vector-blocking vaccines will become important tools for control of ectoparasitic arthropods and vector-borne infectious agents. 

Wikel, S.K. Bergman, D.K. Ramachandra, R.N. (1996) hnmunological-based Control of Blood-feeding Arthropods, in The Immunology of Host-Ectoparasitic Arthropod Relationships (Wikel, S.K., Ed.), pp. 290-315, CAB International, Wallingford, United Kingdom. 

Sandeman, R.M. (1996) Immune Responses to Mosquitoes and Flies, in The Immunology of Host-Ectoparasitic Arthropod... 

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