Parasitology



Concomitant infections, parasites and immune responses


F. E. G.  COX  a1 c1
a1 Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK

Article author query
cox f   [PubMed][Google Scholar] 

Abstract

Concomitant infections are common in nature and often involve parasites. A number of examples of the interactions between protozoa and viruses, protozoa and bacteria, protozoa and other protozoa, protozoa and helminths, helminths and viruses, helminths and bacteria, and helminths and other helminths are described. In mixed infections the burden of one or both the infectious agents may be increased, one or both may be suppressed or one may be increased and the other suppressed. It is now possible to explain many of these interactions in terms of the effects parasites have on the immune system, particularly parasite-induced immunodepression, and the effects of cytokines controlling polarization to the Th1 or Th2 arms of the immune response. In addition, parasites may be affected, directly or indirectly, by cytokines and other immune effector molecules and parasites may themselves produce factors that affect the cells of the immune system. Parasites are, therefore, affected when they themselves, or other organisms, interact with the immune response and, in particular, the cytokine network. The importance of such interactions is discussed in relation to clinical disease and the development and use of vaccines.


Key Words: Concomitant infections; cytokines; protozoa; helminths; bacteria; viruses.

Correspondence:
c1 Tel: +44 020 7927 2333, Fax: +44 020 7580 9075. E-mail: f.cox@lshtm.ac.uk


Metrics