The eosinophilic leukocyte was first noted by Ehrlich in 1879 as an aniline-dye stained leukocyte species in peripheral blood (Ehrlich 1880). Differentiation processes and functions of the cell, however, remained unknown for a long time. The establishment of marrow culture techniques almost a century after Ehrlich’s discovery made it possible to reveal that eosinophils were differentiated in the bone marrow and their stem cells were distinct from those for granulocytes/macrophages or basophils. It was also well known since the 19th century that blood eosinophil levels usually rose in helminthic infections, where a marked eosinophil infiltration occurred around parasites in various...

In the last few decades numerous national governments and international agencies (e.g. the Food and Agricultural Organization of the United Nations) have become increasingly more interested in intensive aquaculture, fish farming and sea ranching. Culturing of fish under controlled conditions can make an important contribution to the nutritional requirements of people in many parts of the world because of its high productivity, and because fish is an excellent source of protein.

As a result of intensive fish culture epizootic outbreaks of diseases (viral, bacterial, fungal and parasitic) have become more common; consequently, there is considerable interest in the organisms that...

Worms, especially parasitic, are not well esteemed by the neighbours, or by auntie, or even by my children. As a topic of conversation, they seldom stimulate the appetite at dinner. Yet those of us duly initiated to the wondrous world of wriggling worms, are fascinated by them. Perhaps many reject them from the popular misconception that, as parasites they live gluttonously in the lap of luxury at the expense of the innocent host — it offends our puritanical senses.

Yet surely worms must search out and compete for food, be affected by their environment, and face the same perils of reproduction...

Immunodiagnostic methods can serve as useful tools for the diagnosis of some parasitic diseases, especially those with tissue involvement. Over the years, a large number of methods have been used in research and diagnostic laboratories to diagnose protozoan, trematode, cestode and nematode infections. For a limited number of common diseases in man and animals, commercial diagnostic kits are now readily available. However, the sensitivity and specificity of a given method may be variable depending on the nature of the antigen used, parasite strains, concurrent infection of the host with other diseases, test conditions and other factors. There is still no...

Angiostrongyliasis is an important zoonotic disease in South-east Asia and the south Pacific region. It is caused by a neurotropic metastrongyloid nematode, Angiostrongylus cantonensis*, and its related species. An unusual feature of the life history of this parasite is the development of its third-stage larva to the adult stage in the central nervous system (CNS) of both permissive and non-permissive hosts. In the latter (which includes man) the adult worm will die in the CNS about 1 month after infection.

The CNS habitat of A. cantonensis provides an unique opportunity to study the immunity to a highly specialized parasite. Theoretically,...

Developing and fast growing organisms depend on a plentiful supply of basic biochemical components. In particular, active biosynthesis of DNA and RNA requires a balanced supply of purine and pyrimidine nucleotides. These nucleotides are also important in sustaining and regulating various metabolic activities of the cell. ATP serves as the major link between energy-yielding and energy-requiring chemical reactions. The adenine nucleotides are constituents of coenzymes. UDP acts as a partner in the transfer of hexoses and CDP serves as a carrier in phospholipid synthesis. The second messenger function of cyclic nucleotides is well known. Recently, the roles of GTP acting...

Parasitic infections belong to one type of infectious diseases with protozoa or helminths as the infectious agents. Although this definition finds a rather shaky scientific ground because protozoa and worms are only remotely related, it does specify that the diseases are caused by well-defined living organisms. They are thus basically indistinguishable from bacterial or fungal infections. Chemotherapeutic controls of parasitic infections should be, in principal, dependent on exploiting metabolic differences between the parasite and the host, such as the antibacterial action of ß-lactams on the bacterial cell wall synthesis.

Most parasites are incapable of growing, differentiating or even surviving in...

Krebs (1985) subtitled his textbook on Ecology, ‘the experimental analysis of distribution and abundance’. Many hypotheses have been erected to explain the distribution and abundance of marine parasites but few have been tested experimentally. We can see where parasites are common and where they are not, but why this is so we can frequently only guess as there is usually little or no experimental proof.

Nevertheless, considerable strides have been made in understanding the ecology of marine parasites. Some of these have contributed to ecology as a whole and others have been valuable to aquaculturalists and to fisheries managers. I...

Nematodes of vertebrates have evolved a greater diversity of solutions to the dilemma of transmission than other helminths and this has allowed them to flourish in a wide variety of locations in the vertebrate body. Their means of transmission are reviewed in the present study. This has not been attempted since the excellent reviews by Chandler et al. (1941) and Chabaud (1955). In the intervening years much interesting information has become available and we have a more complete idea of transmission patterns.

The great diversity in transmission patterns of nematodes can be categorized briefly as follows:

1. Monoxeny — percutaneous, oral....

The Nematoda are among the most successful of animal groups in terms of numbers of species. They abound in most environments from the depths of the ocean to the highest mountain ranges, from the poles to the tropics. They have been particularly successful in invading parasitic environments and may inhabit almost any tissue of a variety of plant and animal hosts.

Life histories of zooparasitic forms are especially varied. Some are monoxenous (capable of being completed in a single host); others are heteroxenous (requiring one or more intermediate host for completion) and a variety of organisms (oligochaetes, molluscs, arthropods, vertebrates)...

Coevolution has become a fashionable topic in evolutionary biology during the past five years (e.g. see Futuyma and Slatkin 1983). One thing that marks most recent discussions is an almost complete lack of appreciation that coevolutionary thinking has been an integral part of parasitology for the past century, going back at least to von Ihering (1891). Thus, while coevolution is like a new toy to students of free-living organisms, it is an old friend to parasitologists. To paraphrase Theodosius Dobzhansky, nothing makes sense in parasitology except in the light of coevolution. This paper is designed to show how precisely our...