関: parasitic disease

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/02 04:01:38」(JST)

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A parasitic disease is an infectious disease caused or transmitted by a parasite. Many parasites do not cause diseases. Parasitic diseases can affect practically all living organisms, including plants and mammals. The study of parasitic diseases is called parasitology. The share of parasitic diseases account for about 14 000 000 deaths per year, representing 25% of global mortality - one in four deaths according to the WHO.

Some parasites like Toxoplasma gondii and Plasmodium spp. can cause disease directly, but other organisms can cause disease by the toxins that they produce.

Terminology

Although organisms such as bacteria function as parasites, the usage of the term "parasitic disease" is usually more restricted. The three main types of organisms causing these conditions are protozoa (causing protozoan infection), helminths (helminthiasis), and ectoparasites.^[1] Protozoa and helminths are usually endoparasites (usually living inside the body of the host), while ectoparasites usually live on the surface of the host. Occasionally the definition of "parasitic disease" is restricted to diseases due to endoparasites.^[2]

Signs and symptoms

Symptoms of parasites may not always be obvious. However, such symptoms may mimic anemia or a hormone deficiency.^[3] Some of the symptoms caused by several worm infestation can include itching affecting the anus or the vaginal area, abdominal pain, weight loss, increased appetite, bowel obstructions, diarrhea, and vomiting eventually leading to dehydration, sleeping problems, worms present in the vomit or stools, anemia, aching muscles or joints, general malaise, allergies, fatigue, nervousness. Symptoms may also be confused with pneumonia or food poisoning.^[4]

The effects caused by parasitic diseases range from mild discomfort to death. The nematode parasites Necator americanus and Ancylostoma duodenale cause human hookworm infection, which leads to anaemia and protein malnutrition. This infection affects approximately 740 million people in the developing countries, including children and adults, of the tropics specifically in poor rural areas located in sub-Saharan Africa, Latin America, South-East Asia and China. Chronic hookworm in children leads to impaired physical and intellectual development, school performance and attendance are reduced. Pregnant women affected by a hookworm infection can also develop aneamia, which results in negative outcomes both for the mother and the infant. Some of them are: low birth weight, impaired milk production, as well as increased risk of death for the mother and the baby.^[5]

Causes

Mammals can get parasites from contaminated food or water, bug bites, or sexual contact. Ingestion of contaminated water can produce Giardia infections.^[6]

Parasites normally enter the body through the skin or mouth. Close contact with pets can lead to parasite infestation as dogs and cats are host to many parasites.

Other risks that can lead people to acquire parasites are walking barefeet, inadequate disposal of faeces, lack of hygiene, close contact with someone carrying specific parasites, and eating undercooked or exotic foods.

Parasites can also be transferred to their host by the bite of an insect vector, i.e. mosquito, bed bug.

Treatment

Albendazole and mebendazole have been the treatments administered to entire populations to control hookworm infection. However, it is a costly option and both children and adults become reinfected within a few months after deparasitation occurs raising concerns because the treatment has to repeatedly be administered and drug resistance may occur.^[7]

Another medication administered to kill worm infections has been pyrantel pamoate. For some parasitic diseases, there is no treatment and, in the case of serious symptoms, medication intended to kill the parasite is administered, whereas, in other cases, symptom relief options are used.^[8] Recent papers have also proposed the use of viruses to treat infections caused by protozoa.^[9]^[10]

References

^ "About Parasites | CDC DPD".
^ "Intestinal Protozoal Diseases: eMedicine Pediatrics: General Medicine". Retrieved 2010-04-25.
^ "Parasite Infection and Parasite Treatment". Retrieved 2010-07-07.
^ "Parasitic Diseases". Retrieved 2010-07-07.
^ "Hookworm disease". Retrieved 2010-07-07.
^ "Parasitic Diseases". Retrieved 2010-07-07.
^ "Disease Burden". Retrieved 2010-07-07.
^ "Parasitic diseases". Retrieved 2010-07-07.
^ Keen, E. C. (2013). "Beyond phage therapy: Virotherapy of protozoal diseases". Future Microbiology 8 (7): 821–823. doi:10.2217/FMB.13.48.
^ Hyman, P.; Atterbury, R.; Barrow, P. (2013). "Fleas and smaller fleas: Virotherapy for parasite infections". Trends in Microbiology 21 (5): 215–220. doi:10.1016/j.tim.2013.02.006. PMID 23540830.

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English Journal

Bioinformatic identification of cytochrome b5 homologues from the parasitic nematode Ascaris suum and the free-living nematode Caenorhabditis elegans highlights the crucial role of A. suum adult-specific secretory cytochrome b5 in parasitic adaptation.

Takamiya S1, Hashimoto M2, Mita T2, Yokota T3, Nakajima Y4, Yamakura F5, Sugio S3, Fujimura T6, Ueno T6, Yamasaki H7.
Parasitology international.Parasitol Int.2016 Apr;65(2):113-20. doi: 10.1016/j.parint.2015.11.004. Epub 2015 Nov 10.
We previously reported that adult Ascaris suum possesses NADH-metmyoglobin and NADH-methaemoglobin reductase systems that are located in the cells of the body wall and in the extracellular perienteric fluid, respectively, which helps them adapt to environmental hypoxia by recovering the differential
PMID 26571414

Cryptic diversity in hymenolepidid tapeworms infecting humans.

Nkouawa A1, Haukisalmi V2, Li T3, Nakao M4, Lavikainen A5, Chen X3, Henttonen H6, Ito A1.
Parasitology international.Parasitol Int.2016 Apr;65(2):83-6. doi: 10.1016/j.parint.2015.10.009. Epub 2015 Oct 29.
An adult hymenolepidid tapeworm was recovered from a 52-year-old Tibetan woman during a routine epidemiological survey for human taeniasis/cysticercosis in Sichuan, China. Phylogenetic analyses based on sequences of nuclear 28S ribosomal DNA and mitochondrial cytochrome c oxidase subunit 1 showed th
PMID 26537836

Development of multiplex serological assay for the detection of human African trypanosomiasis.

Nzou SM1, Fujii Y2, Miura M3, Mwau M4, Mwangi AW5, Itoh M6, Salam MA7, Hamano S8, Hirayama K9, Kaneko S10.
Parasitology international.Parasitol Int.2016 Apr;65(2):121-7. doi: 10.1016/j.parint.2015.10.008. Epub 2015 Nov 10.
Human African trypanosomiasis (HAT) is a disease caused by Kinetoplastid infection. Serological tests are useful for epidemiological surveillance. The aim of this study was to develop a multiplex serological assay for HAT to assess the diagnostic value of selected HAT antigens for sero-epidemiologic
PMID 26519611