PARASITIC DISEASES OF MAN
Parasites can exist inside a host, like the pig parasite Ascaris suum in which case they are deemed to be an “endoparasite”. They may also live on its host such as head lice in humans, and are known as “ectoparasites”. They range in size from unicellular organisms (protazoans) to the multicellular species, such as the Helminths.
In Blaxter’s 2003 paper on the evolution of parasitism, it is suggested that the large range of lifestyles exhibited by these nematodes and their use of a vast array of hosts, would suggest a relationship between the level of parasitism and their adaptability to survive and flourish in a wide range of challenging environments.
Throughout evolutionary history humans have been infected with parasites. Today, it is estimated that over a third of the world's population, mainly those individuals living in the tropics and sub-tropics, are infected by parasitic helminths (worms) or one or more of the species of Plasmodium. The ubiquity of these parasites results in high rates of co-infection It has increasingly been speculated that helminth infections may alter susceptibility to clinical malaria and there is now increasing interest in investigating the consequences of co-infection.
Most of the nematode phyla feed on bacteria, fungi or microorganisms; however some are parasites of plants, animals and man.
The majority of parasitic roundworm diseases are transmitted to humans through soil. In one handful of soil there can be thousands of nematodes, waiting to be transmitted via unwashed hand to mouth transport, or some can even enter the skin. Such nematodes affecting humans include Acaris lumbricoides, Brugia malayi and Wuchereria bancrofti. The latter two cause Elephantiasis.
Cattadori et al experimented on the effects of co-infection of Trichostrongylus retortaeformis and Graphidium strigosum with the myxoma virus. The immune suppressive...