Introduction to Parasitology Definition of Parasitology: ____________________________________________________ Each animal is a host of many parasites; thus, there are far more parasitic organisms on earth than there are non-parasitic organisms. In this course we will concentrate on 3 major groups of parasites: 1. ____________________- flagellates, amebae, malarial organisms 2. ____________________ - parasitic worms such as the flukes, tapeworms,and roundworms 3. ____________________ - insects and arachnids that are ectoparasites and carriers (___________________) of diseases Why do we study parasites? 1. __________________________________________ • parasites provide unique examples of biological phenomena not found in free-living organisms 2. __________________________________________ • Medical importance • Veterinary importance • Economic importance Medical Importance of Parasites Humans are hosts to over ___________ species of parasites. Many of these parasites are causative agents of major public health problems of the world. Recent estimates of prevalence of parasites in the world are: Disease Category # Human Infections Deaths per year Roundworm Ascaris lumbricoides 1.2 billion 60,000 Whipworm Trichuris trichiura 795 million 10,000 Hookworms 740 million 65,000 Filarial worms 657 million 20,000 to 50,000 Malaria 300- 660 million 1-2 million Schistosomes 200 million 20 million Ameba Entamoeba histolytica 50 million 40,000 Liver fluke Clonorchis sinensis 20-30 million ? Chagas’ Disease Trypanosoma cruzi 15 million 43,000 These parasites cause untold suffering and death in the world today. Examples of Medical Importance in the World The life expectancy of an Egyptian is in the mid-40's due to ____________________________. 15 million children in the world will die this year from a combination of malnutrition and _________________________ Over 1 million African children will die this year from the effects of _____________________ Many cases of _____________________, transmitted by fleas, still occur throughout the world. Examples of Medical Importance in the U.S. We in the comfort of the U.S. are not immune from parasites. - Many of us may have been hosts of the ___________________________ - Common parasitic diseases in the Midwest include: _______________________ _______________________ _______________________ _______________________ 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 _______________________________ are brought back by vacationers from the tropics • __________________________ is often employed in areas endemic with many parasites • __________________ immigrants have brought their parasites with them. Veterinary Importance of Parasites Many species of parasites infect our domestic animals: • In Africa, cattle cannot be raised in an area equal to that of the U.S. due to __________________________ • A poultry farmer can be wiped out by _____________________________ • Cattle, pigs, and sheep infected with parasites fail to gain weight and may not reproduce. • Dogs may become infected with _____________________ _______________________________________________ • Cats are infected by many species of __________________ ________________________ Some Veterinary Parasites may infect Humans Several dog parasites are transmissable to humans: • Intestinal roundworm _______________________ can infect humans causing the disease Visceral Larva Migrans • Many species of dog and cat tapeworms can infect humans Cattle are infected with _______________________ that can contaminate drinking water to infect humans ___________________________ occurs in many species of birds and mammals and can cause serious congenital infections in humans. Economic Importance of Parasites Inability to raise livestock in Africa has led to ______________________ Debilitating effects of parasitic diseases on humans results in a loss of ________________________________ Attempts to control parasites by treating infected persons, providing adequate water supplies and sewage disposal, applying costly insecticides, etc. is a major drain on _________________________________________ Thus, an understanding of parasites is important to students in biology, the medical sciences, the veterinary sciences, and public health. WHAT TYPES OF LIVING ORGANISMS ARE PARASITIC? Parasites occur in two of the five kingdoms of living organisms. What are the 5 kingdoms? KINGDOM PROTISTA - contains the single-celled protozoans. Kingdom contains 11 phyla where parasites are found: PHYLUM RETORTAMONADA, PARABASILIA, AND EUGLENOZOA - __________________________ PHYLUM SARCODINA – __________________________ PHYLUM CILIOPHORA - __________________________ PHYLUM APICOMPLEXA - ___________________________ ____________________________________________________ KINGDOM ANIMALIA contains 32 phyla. Parasites of importance are concentrated in 3 phyla. PHYLUM PLATYHELMINTHES – _______________________________ PHYLUM NEMATODA - _____________________________________ PHYLUM ARTHROPODA - ___________________________________ In addition to studying the parasite, an understanding of the HOST ANIMAL is important in Parasitology. 1. _________________________are often complex involving many animal hosts. Example: Chinese liver fluke requires 3 hosts: __________________ ____________________ _____________________ 2. Parasitologists must understand the _______________________________ among animals to know how a parasite can be transmitted from host to host. 3. Parasitologists must have an good understanding the biology of host animals. ______________________________________________________ • where in the body do you find parasites? (most parasites occur in the intestinal tract, but many other organs can serve as a parasite habitat) • how do parasites into and out of the body? (i.e. how does the adult of the Chinese liver fluke get to the liver; how do the eggs of the Chinese liver fluke get out of the human body) ______________________________ - what effects do parasites have on the functioning of the internal systems of their hosts? ________________________- what effects do parasites have on the tissues of their hosts? _____________________________ – how is an organ’s structure and function altered by a parasite? _____________________________ - how does the host's immune system respond to the presence of a parasite? Thus, it is important that a student of parasitology have a good background in the basics of biology.