Introcuctionton Medical Parasitology.pptx

Medical Parasitology is the branch of science that deals with the study of parasites that infect humans, the diseases they cause, and the immune responses of the host to these infections. It also covers the methods of diagnosis, treatment, prevention, and control of parasitic diseases

1. Mr. Osman H. Ali B.Sc. Microbiology, MPH Introduction to Medical Parasitology

2. Learning outcomes To give sufficient knowledge on Principles of medical parasitology To elaborate on the role of parasites in health and diseases To enhance the knowledge on the clinical manifestations of infectious diseases To develop the skill on Laboratory diagnosis of parasites and its treatment To enhance the knowledge on epidemiology of common infectious diseases

3. Parasitology Parasitology is the area of biology/science that deals with organisms that seek shelter and nourishment on or within other living organism s, and relationship between them. This means it forms a synthesis of other discipline on techniques from fields such as cell biology, molecular biology, genetics, ecology, evolution, biochemistry and immunology

4. Conti… Medical parasitology deals with the parasites which infect man, the diseases they produce, the response generated by him against them and various methods of diagnosis and prevention.

5. Point to focus on:- Types of parasites Type of host Sources of infection Portal of Entry Life Cycl e of Parasite Laboratory Diagnosis  

6. Microparasite Small, unicellular & multiplies within its vertebrate host, example like protozoa, fungi, bacteria Macroparasite Large, multicellular and has no direct reproduction within its vertebrate host Ectoparasites- organism which live on the surface of the body eg mites Endoparasites - organism that live within the body of the host are known endoparasites. Example of endoparasites are obligate parasites, facultative parasites, accidental parasites, aberrant parasites & free living   Types of Parasites

7. Endop a r asi t es Obligate parasites- cannot exist without a parasitic life Facultative parasites- organism that under favorable circumstance may live either a parasitic or free living existence Accidental parasites- organism that attack an unusual host Aberrant parasites- organism that attack a host where they cannot live or develop further Free living- non-parasitic stages of existence which are lived independently of a host, eg hookworms

8. Host An organism which harbours the parasite & provides the nourishment and shelter to the parasites Definitive host Intermediate host Paratenic host Reservoir host Compromised host Zoonosis Vector

9. Definitive Host - Either harbors the adult stage of the parasite Or Where the parasite utilizes the external method of reproduction. • In majority of human parasitic infections, man is the definitive host. • In malaria and hydatid disease, man acts as the intermediate host. • Intermediate host - It harbors the larval stages of the parasite. In some cases larval developments are completed in two different intermediate hosts. These are referred as first and second intermediate hosts respectively.

10. Paratenic Host- ( A carrier and transport host)-A host where the parasite remains viable without further development. • Reservoir host- It is a host which harbor the parasite and serves as an important source of infection to other susceptible hosts. Epidemiologically, reservoir hosts are important in the control of parasitic disease

11. • Vector- A vector is an agent, usually an insect, that transmits an infection from one host to another. • Mechanical vector -This is a vector which assists in the transfer of parasitic forms between hosts but is not essential in the life cycle of the parasite. e.g. a housefly that transfers amoebic cysts from infected feaces to food that is eaten by humans.

12. Type of Hos t Definitive host Harbours the adult or sexually mature stages of the parasite (or in whom sexual reproduction occurs) e.g. man is DH for Schistosoma haematobium , while female Anopheles mosquito is DH for Plasmodium species (malaria parasites Intermediate host Intermediate host (IH) that harbours larval or sexually immature stages of the parasite (or in whom asexual reproduction occurs) Paratenic host It is a host is which larval stage of a parasite survives but does not develop further Reservoir host Reservoir host harbors the same species and same stages of the parasite as man. It maintains the life cycle of the parasite in nature and is therefore, a reservoir source of infection for man. e.g. sheep are RH for Fasciola hepatica Compromised Host A host in whom defense mechanism are impaired (e.g AIDS ), absen t (e. g ., congemital deficiences ) Zoonosis An animal infection that is naturally transmissible to humans either directly or indirectly Vector An agent that transmits an infection from one human host to another

13. Host-Parasite Relationship Symbiosis It is an association in which both are so dependent upon each other that one cannot live without the help of the other. None of the partner suffers any harm from the association. Commensalism An association in which the parasite only is deriving benefit without causing injury to its host. A commensal is capable of leading an independent life Parasitism An association in which the parasite derives benefit and the host gets nothing in return but always suffers some injury. A parasite has lost its power of independent life.

14. S I o n u f r e c c e t i o o f n Contaminated water ; Entamoeba histolytica , Giardia lamblia , Balantidium coli, Hymenolepsis   Contaminated freshwater fishes, constitute the source of Clonorchis sinensis   Raw or undercooked meet ( beef/pork , can contribute to T.solium , T.saginata and Trichinella spiralis Dog and cats can cause Toxoplasma spp Contaminated soil; Ascaris lumbricoides , Necator americanus , Strongloides stercoralis , Trichuris trichiura  

15. Portal of Entry Into the Body Skin - A.duodenale, N.americanus, S.stercoralis, Plasmodium spp Sexual contact- Trichomonas vaginalis . E.histolytica and G.lamblia may also be transmitted.   Latrogenic infection Malaria parasites may be transmitted by transfusion of blood from the donor whom positive for malaria   Kissing - E.gingivalis can be transmitted from peson -to-person by kissing   Congenital -Infection with T. gondii and Plasmodium spp may be transmitted from mother to foetus transplacentally  

16. Life Cycle of Parasites No Intermediate Host Protozoa Entamoeba histolytica Giardia lamblia Balantidium coli Trichomonas vaginalis One Intermediate Host Pig Taenia solium T.saginata, Trichinella spiralis Cow Taenia saginata Mosquito Wuchereria bancrofti Two Intermediate Hosts Snail, plant Paragonimus westermani Fasciola spp

17. Immunity in Parasitic Infections Due to their biochemical & structural complexity, protozoa and helminths present a large number of antigens to their host. But immunological protection against parasitic infection is less efficient in human compared to bacterial and viral infections. This is due to parasites a very large in group and more structurally complex. Immune response for parasitic infections are contributed by Cytotoxic T (Tc) cells, Natural killer (NK) cells, activated macrophages and antibody (produced by B-cells).  

18. Laboratory Diagnosis Clinical Specimens: - A) Blood Blood film used in diagnosis for Plasmodium spp , Babesia spp, W.bancrofti B) Stool Used mainly to diagnosis intestinal parasitic infections & helminthic infections of the biliary tract. Example E.histolytica , G.lamblia , B.coli , Ascaris lumbricoides , trichuris trichiura  

19. Parasites Found in Stool Cysts/ Trophozoites (Protozoa) Entamoeba histolytica, Giardia lamblia,Balantidium coli, Cryptosporidium parvum, Enterocytpzoon bieneusi Eggs ( Cestodes) T.saginata, Hymenolepsis nana, Dipylidium caninum Eggs (Tremtodes) Schistosoma mansoni, Fasciola hepatica, S.japonicum Eggs (Nematodes) Trichuris trichiura, Ancylostoma duodenale, Necator americanus, Enterobius vermicularis