Populations of hosts vary extensively in the types and numbers of parasites that the average individual contains. Understanding the factors that lead to this variation is an important goal for parasite ecologists. We characterized patterns of helminth component community structure in whitefish collected from a cluster of 7 lakes located on an isolated plateau in northern Alberta, Canada. Component communities were species rich (5–6 species per lake), high in mean helminth intensity (approximately 80–500 individuals/host), and high in between-lake similarity (50–100%), a pattern consistent with results from studies on whitefish sampled from other localities in Northern Canada and Europe. Multivariate analyses indicated that the structure of the component communities was associated with 2 opposing environmental gradients. One was defined primarily by water colour, the second by phosphorous concentration. Thus, 4 lakes were characterized by a combination of high colour, low productivity, low parasite intensities, and the absence of larval acanthocephalans. Habitat/species associations were less clear as intensities increased, but the 3 remaining lakes tended to have the opposite characteristics. These results provide evidence that variation in helminth component community structure in fish is associated with variation in physicochemical characteristics that are linked to aquatic productivity.

Cyst fluid (CF) of Taenia solium metacestode (TsM) is an important source of serodiagnostic antigens. We have investigated the molecular characteristics of the 120 kDa protein complex in TsM CF purified by fast performance liquid chromatography. The structure of the purified protein was characterized by a variety of proteomic analyses. The protein was found to consist of 2 major components of 42–46 and 22–28 kDa, and shared 3 subunits of 14, 16 and 18 kDa. The 42–46 kDa component was determined to contain 3 additional subunits of 22, 28 and 38 kDa. These 6 subunits were shown to originate from either the 14 or 18 kDa precursor. We assessed the antibody reactivity of the native protein, its individual subunits and the recombinant 14 and 18 kDa proteins, and found that the 120 kDa protein, particularly 14 and 18 kDa subunits revealed high reliability for differentiation of active and mixed stage NC from chronic NC. The subunits of the 120 kDa protein complex identified herein represent some of the low-molecular weight glycoproteins which have been described in several previous studies. Recognizing and understanding the structural and immunological relationship of these proteins will facilitate the development of new serodiagnostic assays.

Recent studies on parasite communities have considered the factors which contribute to variability in parasite infections among populations of one host species. This paper examined parasite assemblages of crucian carp (Carassius carassius) in a natural set-up of two distinctive environments inhabited by the same host species and differing in respect to composition of other fish species: ponds, where extreme conditions prevent other fish species from occurring and lakes, where crucian carp coexist with other fish species. Our aim was to evaluate the significance of parasite exchange, environmental conditions and host suitability for the depauperate parasite assemblages observed in pond crucian carp. As predicted, crucian carp had more diverse parasite species composition in lakes, which supports the hypotheses of increased opportunities for parasite exchange with other fish species and better environmental conditions for the parasites. However, for instance, diplostomids were found only from few fish individuals in very low numbers. Experimental exposure trials with the eye fluke Diplostomum spathaceum in the laboratory indicated that crucian carp were totally resistant to infection, which is exceptional and suggests that the low number of these parasites in crucian carp was due to physiological unsuitability of the host. To obtain a better understanding on the mechanisms underlying the formation of parasite assemblages in these fish, further studies on the relationships between the unique physiology of crucian carp and infection success by other parasite species are needed.

Despite evidence for the existence of interspecific interactions between helminth species, there has been no theoretical exploration of their effect on the distribution of the parasite species in a host population. We use a deterministic model for the accumulation and loss of adult worms of 2 interacting helminth species to motivate an individual-based stochastic model. The mean worm burden and variance[ratio ]mean ratio (VMR) of each species, and the correlation between the two species are used to describe the distribution within different host age classes. We find that interspecific interactions can produce convex age-intensity profiles and will impact the level of aggregation (as measured by the VMR). In the absence of correlated exposure, the correlation in older age classes may be close to zero when either intra- or interspecific synergistic effects are strong. We therefore suggest examining the correlation between species in young hosts as a possible means of identifying interspecific interaction. The presence of correlation between the rates of exposure makes the interpretation of correlations between species more difficult. Finally we show that in the absence of interaction, strong positive correlations are generated by averaging across most age classes.

Davison, A. and Blaxter, M. L. (2005) An expressed sequence tag survey of gene expression in the pond snail Lymnaea stagnalis, an intermediate vector of Fasciola hepatica. Parasitology130, 539–552.

Unfortunately, an error was introduced during the authors' editing of the manuscript. Although Lymnaea stagnalis can host Fasciola hepatica under experimental conditions (Kendall, S. B. 1949, Nature163, 880–881), the impression was inadvertently given that L. stagnalis is a common intermediate vector in nature. The truth is that only some species of the genus Lymnaea are intermediate vectors for F. hepatica, such as L. truncatula.

Unfortunately, an error was introduced during the authors' editing of the manuscript. Although Lymnaea stagnalis can host Fasciola hepatica under experimental conditions (Kendall, S. B. 1949, Nature163, 880–881), the impression was inadvertently given that L. stagnalis is a common intermediate vector in nature. The truth is that only some species of the genus Lymnaea are intermediate vectors for F. hepatica, such as L. truncatula.

Therefore, the title of the paper could be better as ‘An expressed sequence tag survey of gene expression in the pond snail Lymnaea stagnalis, an intermediate vector of trematodes’.

In the INTRODUCTION, the following line should be modified from ‘The life-cycle of F. hepatica in Lymnaea stagnalis is typical of the digenean platyhelminths …’ to ‘The life-cycle of F. hepatica in Lymnaea is typical of the digenean platyhelminths …’

Otherwise, the results and conclusions are not affected.

This comprehensive and thorough work of scholarship is dedicated to the memory of the great American mosquito systematist and biologist, John N. Belkin. Based on an original volume by Carpenter and La Casse, the new authors have added a further 31 species and have revised the original keys. The morphological terms used for adults are substantially revised and they have adopted the chaetotaxy for immature stages developed by Belkin and his colleagues. Species names identified in the keys are followed by a plate number that refers to distribution maps, some of which cover up to 4 species. Following an introduction, a 6-page section on systematics lists new species added to the fauna since 1955, those species resurrected from synonomy and, interestingly, 9 exotic species introduced including the notorious ‘Asian Tiger Mosquito’ Aedes albopictus. This invader was first detected in 1985 and, 20 years later, is now present in 26 states of the Eastern USA. Ochlerotatus, a new genus recently raised from subgeneric status, is discussed briefly, and the authors comment on siblings now recognized through molecular evaluation, for example in the Anopheles quadrimaculatus group. An encouragement for those wrestling with elucidating such complexes is found in the final commentary on this group which notes that, although molecular markers are available, the 5 siblings are now recognized morphologically in all life-stages. The section provides a useful systematic index in tabular form to the Culicidae of the region and their zoogeographic distribution.

The main text begins with the morphology of adult female mosquitoes and is followed by illustrated keys to generic level and then detailed keys to the species of each genus. Similar treatment of the fourth instar larvae follows, again providing illustrated keys.

An extensive bibliography to the topic is provided at the end of the book, with over 800 references.

For the dedicated mosquito worshipper! This book is undoubtedly a must and with its beautifully illustrated keys sets a high standard to follow. It will also, no doubt, prove an attractive volume for more general medical entomologists and enthusiastic students of these irksome, dangerous and fascinating animals.

Natural abundances of the stable isotopes, 15N/14N (δ15N) and 13C/12C (δ13C), were used to study temporal host-parasite relationships of the wild rabbit, Oryctolagus cuniculus (L.). During the 12-month sampling period, temporal isotopic shifts in δ15N were noted for dietary vegetation, host rabbit faeces and fur, but not for muscle or stomach contents. δ15N varied temporally for the parasitic cestode species, Mosgovoyia pectinata but not for Cittotaenia denticulata. Similarly, intestinal parasitic nematodes had apparent species-specific δ15N patterns. Only rabbit fur and intestinal parasitic nematodes did not exhibit temporal shifts in δ13C. Overall, host faeces and stomach contents were isotopically indistinct as a likely consequence of coprophagy. Relative to their host, parasitic nematodes were 15N-enriched, consistent with an increase in trophic level status. Conversely, cestodes were 15N-depleted. Isotopically, each parasite reflected a species-specific relationship with their rabbit host. This technique could be utilized to integrate parasites into food-web studies.

The influence of density-dependent processes on the transmission of parasitic helminths is determined by both the severity of the regulatory constraints and the degree of parasite overdispersion among the host population. We investigate how overdispersed parasite distributions among humans influence transmission levels in both directly- and indirectly-transmitted nematodes (Ascaris lumbricoides and Onchocerca volvulus). While past work has assumed, for simplicity, that density dependence acts on the average worm load, here we model density-dependence as acting on individual parasite burdens before averaging across hosts. A composite parameter, which we call the effective transmission contribution, is devised to measure the number of transmission stages contributed by a given worm burden after incorporating overdispersion in adult worm mating probabilities and other density-dependent mechanisms. Results indicate that the more overdispersed the parasite population, the greater the effect of density dependence upon its transmission dynamics. Strong regulation and parasite overdispersion make the relationship between mean worm burden and its effective contribution to transmission highly non-linear. Consequently, lowering the intensity of infection in a host population using chemotherapy may produce only a small decline in transmission (relative to its initial endemic level). Our analysis indicates that when parasite burden is low, intermediate levels of parasite clustering maximize transmission. Implications are discussed in relation to existing control programmes and the spread of anthelmintic resistance.

Nematology is divided, often arbitrarily, into several ‘subdisciplines’, amongst which the study of plant-parasitic nematodes is predicated on their considerable economic importance world-wide. Further subdivision of the discipline is rarely justified but, in the tropics and subtropics, control of nematode damage is often compromised by lack of knowledge and the cost of conventional management strategies. Thus, there is a need for a comprehensive, informative text on plant-parasitic nematodes of these regions. Plant Parasitic Nematodes in Subtropical and Tropical Agriculture is the second edition of a book whose aim is to meet these requirements.

The issue of species persistence may be a central theme in population ecology, but it is also crucial to infectious disease control. While ecologists aim at preserving biodiversity, disease eradication seeks to drive selected pathogens to global extinction; understanding the mechanisms explaining species persistence at local and regional levels underpins both goals.

In Consumer-Resource Dynamics, Murdoch, Briggs & Nisbet attempt to provide a unifying theory of population dynamics which, starting from the most fundamental of interactions, the consumer-resource duo in a homogeneous environment, expands into multispecies interactions, collapses into single population dynamics, or ventures into unpredictability and spatial heterogeneity. The fact that disease-host systems are hardly mentioned does not detract from the relevance this book can have to parasite population biologists, field parasitologists, and those interested in pathogen and pest control. The following synopsis highlights some salient points.

Chapters 1 and 2 provide conceptual and empirical contexts for the notion of population dynamics, focusing on population regulation and persistence, and discussing the concepts of deterministic and stochastic persistence and the importance of scale. Chapters 3 and 4, on simple predator-prey models, explore the reasons behind these being inherently unstable interactions, which nonetheless embody the various manifestations of population regulation. In particular, Chapter 3 discusses Lotka-Volterra (continuous time) models, whilst Chapter 4 deals with Nicholson-Bailey (discrete time) models, and introduces discrete generation parasitoid-host systems. Chapters 5 to 7 incorporate successive layers of biological realism into the latter, with Chapter 5 introducing stage-structure, Chapter 6 exploring the dynamical effects of various parasitoid life-history strategies, and Chapter 7 bringing aspects of behavioural and evolutionary ecology in focus with population dynamics theory. Chapter 8 is dedicated to competition and multispecies interactions, leading to Chapter 9 on biological control, which ends with a discussion on the need for a resurgence of past interest in placing such control in an appropriate and rigorous ecological framework (the same can be said about disease control programmes). Chapter 10 concentrates on the dynamical consequences of making space explicit, with an insightful discussion on the origins of instability and persistence in single-species vs consumer-resource metapopulations. Chapter 11 develops a ‘phylogeny’ of models by presenting the common origin of frameworks for the description and analysis of predator-prey, parasitoid-host, pathogen-host, and herbivore-plant interactions. It is also argued that few-species models may be appropriate to describe the dynamics of populations living in many-species food-webs (by virtue of decoupling the consumer-resource interaction). The striving for a unifying and coherent population dynamics theory, present throughout the book, culminates in Chapter 12's hierarchy of models, which draws together preceding insights and points towards future theoretical and empirical research directions.

Although not presupposing a mathematical biology background, some familiarity on the part of the reader with simple population ecology models may provide a useful backdrop. The uninitiated will find the various appendices on stability analyses most helpful. The book is very well written, with interspersed tables and boxes that list the various models and their stability properties, and concluding remarks at the end of each chapter that summarize main messages and lead naturally into following chapters. On a more personal note, I found this book profoundly stimulating and found myself often discussing the various insights gained through its reading with my students and colleagues. I particularly enjoyed the sections about age- and/or stage-structured models and the advantages and pitfalls of the (often implicit) assumption of exponentially distributed waiting times. The dynamical differences between constant maturation rates and fixed maturation times are relevant to the problem of incorporating latency in parasite-host models. Ratio-dependency in models, where consumer attack rate depends on the ratio of consumers to prey, is akin to the formulation of the vector to host ratio times the biting rate in (dipteran) vector-borne disease models, most of which do not link vector abundance and biting rates to host abundance. Incorporation of overdispersion in parasitoid-host systems is effected through the widely used negative binomial distribution (May-Hassell models), with the degree of overdispersion mainly independent of host or parasitoid density. The development of stochastic models in which the distributional properties of parasitoid or parasite populations emerge from model results clearly remains a research priority. The question as to whether few-species models can appropriately describe the dynamics of many-species systems is also relevant to the topical theme of multiparasitism and the detection and importance of interspecific interactions in shaping parasite communities. If these interactions were less important than intraspecific effects in determining transmission dynamics, the traditional approach to single-species parasite-host models would be adequate. Finally, the results of the Jansen-de Roos spatial versions of the Rosenzweig-MacArthur model (with logistic growth prey and saturating predator attack rate), in which restricted movement leads to substantial decreases in local and global fluctuations, may have important implications for understanding arthropod-borne disease dynamics, as some vectors have limited mobility (ticks, mites), whilst others may connect to a greater extent pathogen-host subpopulations.

As a zoologist, I have never really understood why those of us who study nematodes continue to partition ourselves into at least two distinct camps, one of which works on the plant-parasitic and free-living species, and the other primarily on animal-parasitic species. And I suspect that nematodes themselves are equally puzzled by this segregation of their ardent scholars. Historically, of course, plant nematologists aggregated in crop research and botany departments, whereas the animal nematologists were stationed in livestock, veterinary, medical and zoological departments of research institutes and universities. I found much of interest in NematologyVol. 1, but I was left with the impression that, whilst the ‘iron curtain’ was beginning to tumble, it still had a long way to fall. We have not yet reached a stage where nematodes as distinct organisms, whatever their niche, take priority in our thinking. But I race ahead. Let us retrace and begin with the details of this volume.

It could be argued that much of evolution is really coevolution. Organisms do not exist in an ecological vacuum, but as parts of a network of interacting species. A given species may compete with others for access to prey species used as food, while itself serving as food to predator and parasite species. Natural selection will drive reciprocal evolutionary changes between interacting species. Across its geographical range, a species will encounter different local networks, since the same set of species do not co-occur everywhere. Thus, coevolutionary outcomes will vary in space, forming a geographical mosaic shaped by local adaptation and gene flow. This is the theme of John Thompson's new book, in which the author develops a conceptual framework for the study of coevolution.

On the basis of high prevalences of Echinococcus multilocularis in the growing fox populations in Central Europe, its total biomass may have increased significantly in the past 20 years. E. multilocularis is now also found in areas outside the known endemic area in Central Europe. Therefore, E. multilocularis, the causative agent of a serious parasitic zoonosis, might be of major concern for public health and a challenge to control. Some experimental field trials to control E. multilocularis using an anti-worm drug reduced parasite burden in a contaminated region during the control campaign, but failed to eradicate the parasite completely. It was our aim to develop a mathematical model describing the biomass of egg, larval, and adult worm stages of the E. multilocularis life-cycle, and simulate a hypothetical control campaign. Additionally, we derived the reproduction number of this parasite and explored conditions for the persistence of the parasite's life-cycle. Our model shows that while control campaigns rapidly reduce the worm burden in the definitive host, and consequently eggs in the environment, the pool of larvae in the intermediate host remains large. The parasite's life-cycle persists in a region where prevalence in the intermediate host is low (∼1%). Therefore, we conclude that the parasite is likely to re-emerge if control is discontinued on the basis of reduced worm population. Continued treatment of the definitive host is required to eradicate the larval stage of the parasite from the intermediate host population.

This highly topical book offers information on two groups of communicable diseases: the first being zoonoses, with animals playing an essential role in maintaining the infection in nature and man is only an accidental host. The second group comprises the diseases common to man and animals, where they generally contract the infection from the same source, and the animals may contribute in particular to the distribution and actual transmission of infections.

Ecological and social changes, along with the migration of large numbers of people between continents, have caused the spread of once endemic diseases, which can now pose a threat in distant communities. The risk of bio-terrorism has highlighted the need for detailed knowledge of those diseases in terms of their epidemiology, mechanisms of transmission to humans, diagnosis and control.

In each volume, the groups of communicable diseases are listed in alphabetical order, which makes it easy to use. The great asset of this publication is that a number of pages devoted to each disease follows its incidence rate and pathogenicity for humans and animals. Less serious infections are listed briefly while those possessing serious threat are described in great detail. Each chapter is followed by the list of most important references, though some of them are not the most up-to date.

What also makes it easy to use for a reader is the listing of the synonyms for each disease, and chapters divided into paragraphs with headings such as etiology, geographic distribution, occurrence in man and animals, symptoms, sources of infections and mode of transmission, and the role of animals in its epidemiology, diagnosis and control. However, the tables, figures and photographs are included unevenly in the volumes. The transmission cycles are mostly presented in the second volume, while in the third one regarding Parasitoses they are completely missing. And it is in particular in Parasitoses, where the life-cycles are often quite complicated and for a better understanding of the mode of transmission, such illustrations would be very suitable.

What might be rather confusing are a few listed synonyms, which in several cases are somewhat contradictory in terms of their suffixes – osis (-iosis) and -iasis, even if the agents have the same generic suffix – e.g. Balantidiasis versus Balantidiosis (Balantidium coli,) and Cryptosporidiosis (Cryptosporidium spp.).

In conclusion, the publication, primarily targeted at academics and students in schools of public health, medicine and veterinary medicine, researchers as well as the staff of public health and veterinary health institutions, provides an attractive read – not just for everyone who must or wants to be familiar with the subject, but also for all seeking a broad overview in the world of known and emerging zoonoses.

Readers approaching this book should not expect a review of the diverse forms of parasitic organisms or a series of illustrations of the extraordinary adaptations parasitism has provided. This is a book of theory and graph, of generalization and synthesis. It is aimed at a broad audience, with the hope that the reader ‘when later gazing at a bird gliding overhead, will see not just the bird, but will also see (or at least imagine!) the flying assemblage of parasite species’.

Four years on from the 2nd Edition of this useful introductory text this book remains good value at a modest price rise of only £5.00. In twenty chapters Professor Service follows his well-worked and consistent pattern in each chapter by describing the morphology of each group of vectors, followed by life-cycle, medical importance and control. The further reading information provided at the end of each chapter has been updated wherever relevant. In addition, as an aide-mémoire to revising, certain key words now appear in bold. In many groups, new information is provided on the numbers of species now described. In the case of mosquitoes this is now 3300, an increase of 100 and there are now 4 further genera including Ochlerotatus, a previous subgenus of Aedes. Outstanding developments in control include the innovative development of manufactured bed nets that are impregnated with synthetic pyrethroids, which are designed to release the active molecule over periods as long as four years. Mike Service is, however, cautious, and warns that despite our great hopes for this new development, the incidence of resistance to pyrethroids is a realistic potential threat to its success. In similar vein it is noted that mosquitoes in the laboratory have been observed to develop resistance to the bacterial insecticides Bacillus thuringiensis and B. sphaericus. This has not as yet proved to be a problem in the field with mosquitoes, but experience with agricultural pests, such as the diamondback moth, indicates the need for vigilance.

Back in the early 1960s, when the curtain was falling on British colonial administration in Africa, the newly-created Ministry of Overseas Development decided to gather together for posterity the expertise and experience of authorities on tsetse and trypanosomiasis control. Weighing in at three and a half pounds, the resulting publication, ‘The African Trypanosomiases’ edited by Colonel Hugh Mulligan and published in 1969, has since been a baseline not only for investigators in the field but also for pure scientists working on related problems at the laboratory bench. The editors of the present volume were inspired by the enormous progress made in trypanosomiasis research over the last thirty years to produce ‘an update of Mulligan’ – so, how do the two books compare? Well, amazingly, their weights are exactly the same – but content and coverage are, as might be expected, very different.

We regret that in the article by M. van der Kolk et al. in Parasitology (2005) Vol. 130 (1), 13–22, W. Sauerwein should have been given as R. W. Sauerwein.

We apologise to the author and readers for this error.