Foreword
In developing this resource, I consider it essential that students get to know the parasite assemblages themselves in order to understand the ways in which they interact with their hosts and cause disease, as well as to understand the logic behind different diagnostic techniques and various treatment and control strategies. By learning basic parasitological information in a clinical context, it is hoped students will develop their skills to:
• diagnose the major parasitic groups in host tissues and organs;
• deduce their modes of transmission from their sites of infection;
• indicate their pathogenicity for different host groups;
• identify boundaries to their distribution and abundance;
• recommend appropriate treatment and control strategies; and
• assess their significance with respect to human and animal health and welfare.
The impetus for this work was provided by the apparent absence of textbooks giving the right degree and mix of biological and clinical information. Many general biology texts only give cursory information on a small range of parasites while most clinical texts concentrate on a few of the most serious parasitic diseases of medical and veterinary significance. At the other end of the spectrum, there are many specialist texts dealing exclusively with individual parasitic groups and the information presented can be overwhelming to students. This electronic resource was designed in an attempt to find some common middle ground between the generalist and specialist texts available. Knowledge of the many different parasite assemblages is essential for their differential diagnosis, treatment and control.
I wrote this resource part-time over a decade, beginning with parasites of medical importance and moving onto parasites of domestic animals and then wildlife, including fish. Parasite genera were selected on the basis of their significance to human and animal health and also as requested by students. Early versions of essays on individual genera were incorporated into teaching materials released to undergraduate students enrolled for a third-level course on parasitology at The University of Queensland. Their feedback was crucial for revision and expansion. A compilation of 30 essays was made available on-line through the Australian Society for Parasitology (ASP) website, an organization that generously provided funds to employ a biological artist to draw new life-cycle diagrams. The preliminary PARA-SITE website proved popular as an educational tool, so the decision was made to expand the e-resource to include more parasites of interest. There are now around 250 parasite genera covered in this revised version. It is hoped that other ASP Fellows and members may add to this resource over the coming years, providing a knowledge bank and legacy for future generations of parasitologists.
Peter O’Donoghue
Brisbane, 2025
Notes on format
Information is summarized for over 250 parasite genera, including protozoa, helminths and arthropods. Each genus is dealt with separately and provides a complete introductory account, so there is some preliminary repetition for closely-related genera (this was done so that each genus could stand-alone when the resource is delivered electronically). The following format has been used throughout.
Genus
Name and type of parasite
Overview
Succinct summary covering parasite identity, basic biology and clinical significance.
Classification:
Taxonomy presented as Domain, Supergroup, Phylum, Class, Order, Family, Genus et al.
Please note that parasite taxonomy is constantly changing as new characters sets are explored and incorporated into phylogenetic classification systems. There is no perfectly correct system, merely current opinion. Parasites have conventionally been classified on the basis of phenotypic characters (morphology, biology, hosts), but now advances in molecular biology have allowed extensive genotypic characters (gene sequences, proteins) to be used to infer phylogenetic relationships between taxa. In some cases, genotypic characterization has ratified phenotypic classifications, but in other cases, molecular data has suggested alternative groupings. In this resource, an attempt has been made, where appropriate, to link conventional and contemporary classifications to provide some continuity between old and new schools of thought.
Information has been gleaned from numerous electronic sources, as would be available to anyone using contemporary web search engines. It has been kept up-to-date as far as possible, but remember that taxonomy is an ever-changing game.
Parasite biodiversity and host range:
This section introduces that type of parasite being covered, beginning with its main characteristics and ending with its biodiversity (species richness) in the form of a host-parasite species list. These lists are compilations of records retrieved by searching public data-bases and published reviews and papers. Where appropriate, they include synonyms, species inquirenda, nomen dubia and sometimes species that have since been reassigned to other genera. I have retained as many old records as possible to help guide readers through the complex terrain of species diversity as presented on the internet. I will leave it to specialists to revise listings by lumping or splitting species. During the development of this resource, students requested that I provide common names for hosts rather than just their scientific binomial names to aid recognition (in contradiction to conventional practice). I initially attempted to provide both, but the tables became very cumbersome. I have listed the hosts together with their familial designations to indicate the range of presumptive host specificity (narrow or broad).
Parasite morphology:
This section describes the numbers and types of developmental stages formed by each parasite genus, with information given on size ranges and morphological appearances.
Site of infection:
The anatomical location (tissue tropism) is given for each parasite developmental stage within their various hosts.
Pathogenesis:
The pathogenic potential (virulence) is indicated for infections/infestations, noting major clinical signs and risk factors for disease.
Developmental cycle and mode of transmission:
Details are given on the life-cycles of representative species (note that the life-cycles of most species remain to be determined). The major modes of transmission are indicated: direct v. indirect; horizontal + vertical.
Differential diagnosis:
The usual methods for diagnosing infections are reported, together with notes on new or experimental techniques.
Treatment and control:
Therapeutic and prophylactic options for disease control are provided, but specific information (doses, courses, etc) are not stated as treatment should be carried out under professional medical/veterinary supervision. Preventive measures are summarized: covering hygiene, sanitation, disinfection, vector control, vaccination and education, as appropriate.
Disclaimer
This resource was developed for professional students of parasitology, notably those at tertiary or quaternary levels of higher education where one of their first main tasks for a project or thesis is to conduct a literature review of their parasite of interest. To this end, I conducted reviews for the each of the 250+ parasite genera covered in this resource by accessing material principally through targeted library searches (including research papers, case reports and topical reviews). Any errors remaining in the foregoing reviews are my own.
While the internet provides unprecedented access to material, it can be a medium for mediocrity if one ventures away from accredited sources. There are some good credible sites managed by professional societies, health organizations and museum agencies, but there are a plethora of casual sites meaning well but often perpetuating misinformation, inaccuracies or myths. The Australian Society for Parasitology (ASP Inc.) has taken on the responsibility of maintaining the PARA-SITE web resource for future generations of parasitologists, so we would welcome any comments or suggested corrections (bear in mind that taxonomy changes over time as different characters are explored or revealed, so we do not want to enter into debate over classification – that is best left to experts specializing in particular parasite groups).
When compiling species tables (host-parasite lists), it was often difficult to reconcile information available from different data-bases for a variety of reasons (missing records, naming confusions, incomplete descriptions, etc). I have bundled this material together in holistic fashion (as would any student) but I have attempted to indicate the current status of species when known (e.g. as bonafide species, synonymized species, reassigned species or species inquirenda). Note that these species lists are not intended as definitive works cast in concrete but are merely consolidated lists with comments. It was also often difficult to review species data characteristic for the whole genus, especially for speciose genera and those exhibiting highly variable traits. Nonetheless, information given is most pertinent to exemplar species (highlighted in orange) which have been shown to be of medical or veterinary significance. Specific drug treatments and dosages are not given for any suggested chemotherapeutic interventions as treatment of afflicted individuals should be carried out under medical or veterinary supervision.
PARA-SITE is intended as an educational electronic resource available to any interested parties and the text and life-cycle diagrams have been provided without any copyright restrictions so they can be used in future teaching and research. Each genus is presented as a stand-alone chapter which can be accessed via the indices or by specific searches. The consolidated e-book is therefore unlike a conventional book as the background material is repeated within each chapter rather than being consigned to separate introductory chapters. This was done deliberately to make each chapter self-contained and thus more user-friendly for electronic platforms.