Ectoparasitic infestations

Modern treatment of ectoparasitic infestations has become fragmented due to the emergence of parasite strains resistant to one or more of the classes of compounds discussed below. A review of the earlier broad spectrum compounds, some of which remain in use today in those parts of the world where significant resistance has not emerged, is available (B-68MI10800). 

This chapter discusses the major parasitic diseases, including protozoan diseases (amebiasis, malaria), helminthic infections (as-cariasis, enterobiasis), and ectoparasitic infestations (head and body lice). Emphasis is placed on diseases seen more frequently in the... 

Preliminary studies indicated that ivermectin has the potential to be the drug of choice for ectoparasitic infestations (mites, lice) of humans as well. Recently, there is growing evidence that scabies can also be treated by oral administration of ivermectin. Treatment of scabies is very difficult, and relapse is frequent after topical scabicidal therapy. Ivermectin has been proven to be a safe and effective alternative for the therapy of severe Sarcoptes scabiei infestation unresponsive to conventional treatment. 

There is a patent (U.S. Patent 6,800,294) on an antiparasitic formulation comprising eucalyptus oil Eucalyptus globulus), cajeput oil Melaleuca cajuputi), lemongrass oil, clove bud oil (5. aromati-curri), peppermint oil (M. piperita), piperonyl, and piperonyl butoxide. The formulation can be used for treating an animal body, in the manufacture of a medicament for treating ectoparasitic infestation of an animal, or for repelling parasites. 

A parasite that lives outside the body of the host is called an ectoparasite. Approximately 6 to 12 million subjects become infested with pediculosis (lice infestation) yearly in the United States. Pediculosis is usually associated with poor hygiene, and infections are passed from person to person through social and sexual contact. 

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. 

In veterinary medicine, the control of ectoparasites is of great importance due to their effects on livestock profitability and the health status of animals. Infestations on livestock can cause intense irritation leading to poor condition, weight loss, reduced milk yield, and hide or fleece damage. Furthermore, many species of acari are responsible for transmission of diseases to the host animals themselves or act as vectors of a number of diseases to humans [6]. 

Ectoparasites such as ticks, mites and haematophagous flies together with certain endoparasites may be "managed" by use of avermectins (macrocyclic lactones) or hormone analogues and by Immunization of the hosts with antigens derived from the vectors or parasites themselves. Recently this combined approach has been used most effectively against helminth infestations as well as against ticks and flies. Use of components of host odors and pheromones to trap, sterilize or kill tsetse flies is described as well as inexpensive methods of crop and livestock protection, such as oils and plant extracts, used traditionally in less developed countries. 

The systemic route remains the most desirable method for controlling haematophagous pests or ectoparasites, especially if they happen to be vectors of virus, protozoan or metazoan inflicted diseases. It has been understood for quite some time that the bite of the tick transfers substances, like an anticoagulant for Instance, which somehow eventually leads to acquired resistance to infestation by that tick (37). Therefore, use of proteins from the ectoparasite, as antigen to immunize livestock likely to be exposed... 

A.M. Bullock (1985). The effect of ultraviolet-B radiation upon the skin of the plaice, Pleuronectes platessa L., infested with the bodonid ectoparasite Ichthyobodo necator (Henneguy, 1883). J. Fish. Dis., 8, 547-550. 

Infestations with ectoparasites such as body lice and scabies are conunon throughout the world. These conditions have a significant impact on public health in the form of disabling pruritus, secondary infection, and in the case of the body louse, transmission of life-threatening illnesses such as typhus. Topical and oral medications are available to treat these infestations. 

Rowland, 1988b). Ponds are treated prophylactically with formalin in winter and spring to prevent infestations of C. hexasticha and other ectoparasites (Rowland and Ingram, 1991). 

Gurjanova, T. M., Molchanov, M. I. and Kochetova, N. I. (1977) Changes in the hemolymph protein composition under the infestation of the fox-colored sawfly larvae moth with the ectoparasites. Zool. Zh., 56, 648-50. 

Ectoparasites, Scabies in man is now rapidly curable by local application of either benzyl benzoate or lindane. Pediculosis (infestation with one or other kind of lice) is similarly cured with carbaryl i2,2S isobomyl thiocyanate, lindane, or DDT. 

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