Parasitic infestations

Inebriation. The condition of being drunk. Infestation. Parasitic attack or subsistence on the skin and its appendages, as by insects, mites, or ticks. 

Coccidiosis. Infestation with coccidia, an intestinal parasite. 

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. 

Organic and low input farmers who are dependent on anthelmintics should optimise the benefit of these treatments by monitoring levels of infestation on their farms. By minimising treatment frequency, optimal timing of the treatments should result in a parasitological status that is both tolerable for herd health and also economically justified. With the exception of the large liver fluke, F. hepatica, the parasites treated in this chapter should therefore not be controlled on the basis of a standardised schedule, which most likely leads to excessive use of anthelmintics. 

In Alaska, reindeer (Rangifer tarandus) infested with reindeer warble fly (Oedemagena tarandi) produced hides of little value and low quality meat. Reindeer warble flies were not controlled by pour-on applications of famphur because the product was unable to penetrate the hair coat of reindeer however, intramuscular injections were effective (Ivey et al. 1976). In Norway, Sweden, and Finland, famphur was the most promising control agent against reindeer warble fly and reindeer nostril fly (Cephenomyis trompe) — two parasites that together caused a 15 to 20% annual loss of total yield in reindeer husbandry (Nieminen et al. 1980). 

Allelopathy found hopeful utilization in plant protection against parasite weeds. The main world parasitic species are the witchweeds (Striga spp.), broomrapes (Orobanche spp.), and eventually dodder (Cuscuta spp.). Witchweeds and broom-rapes attack many economically important crops especially throughout the semi-arid regions. Early detection of parasitic weed infestation and protection is difficult because of the growth habit of a root parasite and huge production of dust-like seeds viable up to 20 years (Kebreab and Murdoch 1999). 

A chemical stimulant, a root exudate, is required to break seed dormancy of a parasitic weed and initiate seed germination. Upon receiving a signal for germination, a radicle emerges from the seed coat. However, an additional chemical signal is needed for the radicle to penetrate host roots and form a haustorium. Therefore several plants can serve as catch crops or trap crops for the reduction of the parasitic weed seed bank in infested soil. 

Trap crops or so-called false hosts are crops able to stimulate parasite seed germination but are not themselves parasitized. Each trap crop control at least one species but not all genus species. (Abebe et al. 2005). Dodder (Cuscuta spp.) infestation can be effectively reduced by growing cereals or other grass crops (false hosts) continuously for several years (Dawson 1987). Other examples of suitable trap and catch crops are given in the Table 14.3. 

Dawson JH (1987) Cuscuta (Convolvulaceae) and its control. In Weber HC, Forstreuter W (eds) Parasitic flowering plants, Philipps-Universitat, Marburg, Germany, pp 137-149 De Almeida FS (1985) Effect of some winter mulches on the soil weed infestation. In Proceedings of 2nd Brighton Crop Protection Conference - Weeds, British Crop Protection Council, London, pp 651-659... 

Cline, L.D. and Press, J.W. 1990. Reduction in almond moth (Lepidoptera Pyralidae) infestations using commercial packaging of foods in combination with the parasitic wasp, Bracon hebetor (Hymenoptera Braconidae). J. Econ. Entomol. 83, 1110-1113. 

In Ayurvedic medicine, coconut oil infused with herbs has been used medicinally for almost 4000 years as an effective treatment for skin diseases caused by infestation with parasites, such as scabies and head lice. Today, about 20 billion coconuts are grown each year, and although the major producers are the Philippines, India, and Indonesia, virtually everywhere the coconut palm grows — in the tropical regions of Latin America and East Africa, as well as Asia, the Pacific Islands, and the Philippines — coconut products serve as a dietary staple. ... 

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. 

Taylor Q) found the endoparasitic dinoflagellate Amoebophrya ceratii in phytoplankton samples taken in 1965 from Sequim Bay, Washington (Figure 1). He reported that 30-40% of the G. catenella cells in 3 samples taken at intervals over 4 months were infested by this parasite. He suggested that the parasite offered a remote possibility of biological control of catenella, the causative organism of many of the outbreaks of paralytic shellfish poisoning (PSP) on both sides of the North Pacific (2, 3, 4, and in the Southern Hemisphere (j6). 

A potentially significant factor in the decline in abundance of catenella is the infestation by A. ceratii which results in the ultimate removal of the host cells from the water column. The percent of parasitism increased markedly from 2.5% prior to the peak of the bloom to 9.5% at the peak and 32% five days later (Figure 5). During that 9 day period of a 12-fold increase in infestation rate, the catenella population first increased and then decreased by 80% in 5 days. During this time the divison rate of G catenella dropped by at least 50%. 

The percentage of cells throughout the water column which were infested by A. ceratii rose from 2% at the peak of the bloom to 22% five days later during the decline (Figure 7). (In samples from the 1 m depth during and after the decline approximately 50% of the cells were parasitized.)... 

In both blooms it is apparent that parasitism was one of several factors contributing to the decline of the population. (In 1983 parasitism alone would not have accounted for the rate of decline of the . catenella populations even if the division rate had dropped to 0.) Although the relative importance of parasitism will vary with conditions, the magnitude of infestation in these blooms indicates that parasitism must have been a major factor in controlling. catenella populations. 

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