• Medical parasitology: the study and medical implications of parasites that infect humans.

• Molecular parasitology: the study of the molecular biology of parasites.

• A parasite: a living organism that acquires some of its basic nutritional requirements through its intimate contact with another living organism. Parasites may be simple unicellular protozoa or complex multicellular metazoa.

• Eukaryote: a cell with a well-defined chromosome in a membrane-bound nucleus. All parasitic organisms are eukaryotes.

• Protozoa: unicellular organisms, e.g. Plasmodium (malaria), trypanosomas, Leishmania.

• Metazoa: multicellular organisms, e.g. helminths (worms) and arthropods (ticks, lice).

• An endoparasite: a parasite that lives within another living organism – e.g. malaria, Leishmania, Giardia, Trypanosoma, helminths

• An ectoparasite: a parasite that lives on the external surface of another living organism – e.g. lice, ticks

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• Host: the organism in, or on, which the parasite lives and causes harm (or acts as a reservoir)

• Definitive host: the organism in which the adult or sexually mature stage of the parasite lives.

• Intermediate host: the organism in which the parasite lives during a period of its development only.

• Zoonosis: a parasitic disease in which an animal is normally the host - but which also infects man.

• Vector: a living carrier (e.g.an arthropod) that transports a pathogenic organism from an infected to a non-infected host. A typical example is the female Anopheles mosquito that transmits malaria

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• Although parasitic infections occur globally, the majority occur in tropical regions, where there is poverty, poor sanitation and personal hygiene

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IntroParasite Diseases No. people infected Deaths/yr

Plasmodium malaria 273 million 1.12 million

Soil transmitted helminths:

• Roundworm (Ascaris)

• Whipworm (Trichuris)• • Hookworm

(Ancylostoma and Necator)

Pnemonitis, intestinal obstruction

Bloody diarrhoea, rectal prolapse

Coughing, wheezing, abdominal pain and anaemia

2 billion 200,000

Schistosoma Renal tract and intestinal disease

200 million 15,000

Filariae Lymphatic filariasis and elephantiasis

120 million Not fatal but 40 million disfigured or incapacitated

Trypanasoma cruzi Chagas disease (cardiovascular)

13 million 44,000

African trypanosomes African sleeping sickness 0.3 – 0.5 million 68,000

Leishamania Cutaneous, mucocutaneous and visceral leishmaniasis

12 million; 2 million new cases/yr

100,000

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Why do we study parasites?

• Parasites provide unique examples of biological phenomena not found in free-living organisms.

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Why do we study parasites?

• Parasites provide unique examples of biological phenomena not found in free-living organisms.

• Medical Importance

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Why do we study parasites?• Parasites provide unique examples of biological

phenomena not found in free-living organisms.• Medical Importance

• Veterinary Importance

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Why do we study parasites?

• Parasites provide unique examples of biological phenomena not found in free-living organisms.

• Medical Importance ********

• Veterinary Importance

• Economic Importance********

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Elephantiasis

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• Lymphatic filariasis, commonly known as elephantiasis, is a neglected tropical disease. Infection occurs when filarial parasites are transmitted to humans through mosquitoes. When a mosquito with infective stage larvae bites a person, the parasites are deposited on the person's skin from where they enter the body. The larvae then migrate to the lymphatic vessels where they develop into adult worms in the human lymphatic system.

• Wuchereria bancrofti, which is responsible for 90% of the cases• Brugia malayi, which causes most of the remainder of the cases

• Adult worms lodge in the lymphatic system and disrupt the immune system. They live for 6-8 years and, during their life time, produce millions of microfilariae (small larvae) that circulate in the blood.

• Lymphatic filariasis is transmitted by different types of mosquitoes for example by the Culex mosquito, widespread across urban and semi-urban areas; Anopheles mainly in rural areas, and Aedes, mainly in endemic islands in the Pacific

http://www.youtube.com/watch?v=dnWwHthkGkY&feature=related

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• African trypanosomiasis, also known as "sleeping sickness," is caused by microscopic parasites of the species Trypanosoma brucei. It is transmitted by the tsetse fly (Glossina species), which is found only in rural Africa.

• http://www.youtube.com/watch?v=EnsydwITLYk

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• Chagas disease is named after the Brazilian physician Carlos Chagas, who discovered the disease in 1909. It is caused by the parasite Trypanosoma cruzi, which is transmitted to animals and people by insect vectors (triatomines) and is found only in the Americas (mainly, in rural areas of Latin America where poverty is widespread). Chagas disease (T. cruzi infection) is also referred to as American trypanosomiasis.

• http://www.youtube.com/watch?v=7q9PTljtRhE

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Importation of Parasites from Tropics to the U.S.

• Movement of persons from all areas of the world have introduced parasitic diseases into the U.S. – Numerous cases of malaria are brought back by vacationers

from the tropics.– Service personnel are often employed in areas endemic with

many parasites.

– Many immigrants have brought their parasites with them.

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