Delivered by Prof. E.U. Edosomwan (Professor of Parasitology)
Topic: ‘Invasion of Territories without Limits: Parasites and their Hosts’
Parasites are organisms that are physiologically or metabolically dependent on their host and have the potentials to cause harm by their invasive nature. They are found everywhere and cause diseases to plants, animals or man. Parasites enter their hosts by active invasion; their transmission success is often based on mass production of invasive larval stages which undergo larval migration in the host until they get to their preferred site and grow into the adult stage. The adult parasites produce eggs which find their way to the outside environment in order to perpetrate the cycle of infection, reproduction and invasion. These parasites invade different territories in the hosts’ body causing disease or even death if not prevented, hindered or stopped.
Parasites successful survival depends mainly on evading the host immune system by penetrating and multiplying within cells, varying their surface antigens, eliminating their protein coat and modulating the host immune response. Immunosuppression is sometimes caused directly by parasite products and involves antigenic mimicry, which often appears in association with parasitic diseases. The host has the ability to respond to this invasion of parasites by the production of antibodies and cells that are able to engulf or quarantine the parasites.
Parasites can be controlled in several ways: by provision of adequate nutrition, provision of housing and potable water supply; good environmental sanitation; good hygiene practices; by controlling the vectors and intermediate hosts of the parasites; use of vaccine; early monitoring and reporting of disease prevalence using techniques such as remote sensing and geographic information system. Remote sensing is the acquisition of information about an object or phenomenon on earth, without directly making physical contact. It refers to the use of aerial photography and sensor technologies. Remote sensing application has been used to predict the occurrence of schistosomiasis, malaria, filariasis etc., after which control measures can be embarked upon, for instance aircrafts have been used to spray hot water or insecticides to control parasite vectors. Diagnosis is needed for the commencement of treatment and determination of control measures. Prevention and treatment of infected host can be achieved by chemotherapy (drugs) and vaccination.
Socio-cultural and behavioural practices are very important in parasite invasion. The unwilling attitudinal change predispose man to invasion of hosts by parasites without limits.