CURRENT RESEARCH INTERESTS OF
ASSOC PROF RICK SPEARE

PARASITES

Head lice

The trapeze artist grounded!

[For larger image (197K in JPG) click on louse]

Pediculus humanus capitis, the human head louse, sucks blood from the scalp with minute mouthparts it extrudes from its small mouth. Each of the six legs end in a claw which is used to grasp a hair. The claws allow the louse to move rapidly through the forest of hairs and to fasten strongly onto them to prevent itself being dislodged.

Head lice are the most common of the ectoparasites using humans as a host. Control is made difficult by lice becoming resistant to insecticides. We have been conducting therapeutic trials to evaluate the efficacy of currently available and new insecticidal preparations.

In a study on the prevalence of pediculosis in a state primary school in Brisbane in 1997, we found 22% of children had active infections, while a further 13% had nits, but no active lice, indicating that they had been recently infected, but did not currently have an active infection.

We are also interested in the ultrastructural anatomy of Pediculus humanus capitis. The antennae of lice have four types of sensory organs including the tuft organs (shown here) on the forth and fifth segments. For a more comprehensive description of the ultrastucture of the head louse see the poster presented at the New Images in Tropical Medicine conference in July in Townsville.

Hookworms
[For larger image (56K in JPG) click on hookworm]

Ancylostoma caninum, the dog hookworm, causes eosinophilic enteritis in humans. This disease responds readily to mebendazole.

Hookworms of zoonotic significance are commonly found in dogs and cats in North Queensland. A study by Louise Stewart found dogs in Townsville were infected by Ancylostoma caninum while cats were infected with A. caninum, A. tubaefome, and A. ceylanicum.

A comparison of the ITS-2 gene of A. caninum, A. tubaeforme and A. ceylanicum using endonuclease restriction patterns showed that the morphological species were genetically distinct with A. ceylanicum being less closely related.

Scabies

Scabies is a cosmopolitan problem, but sometimes reaches high prevalences in Aboriginal and Torres Strait Islander communities, nursing homes, and in hospital wards. Our work on scabies has concentrated on the morphology and taxonomy of Sarcoptes scabiei, and on the response of mites and clinical scabies to acaricides. An in-vitro test developed by Rick Speare and Aileen McConnell to assess susceptibility of S. scabiei to acaricides provides valuable data to the clinician to allow appropriate therapy to be chosen.

Strongyloides

The taxonomy of Strongyloides has been the major focus of my work. A review of the genus described criteria useful for identification of species, the effects of artifactual changes on morphology of specimens, and techniques useful for working with Strongyloides.

S. felis, a species closely related to S. stercoralis, was rediscovered in cats in North Queensland. Like S. stercoralis, S. felis forms autoinfective larvae in the body of its host. This is an unusual feature of the genus, with major implications for parasite persistence and pathogenicity, and has been demonstrated only for S. stercoralis and S. felis.

Recent work on Strongyloides in dogs in the Northern Territory has shown that dogs from some Aboriginal communities are infected with S. stercoralis.

ZOONOTIC DISEASES

Pteropid lyssavirus

The primary case of pteropid lyssavirus in Australia was a black flying fox (Pteropus alecto) found behaving agressively in Townsville on 2 January 1995. This region now has two cases reported in this species with a third case in a little red flyng fox, Pteropus scapulatus from Townsville, and a P. alecto from Charters Towers.

We have been working on the difficulties of diagnosing lyssaviral disease from other diseases that cause neurological signs, and on the orphan flying fox's ability to develop a titre after rabies injections.

Japanese encephalitis

A survey of antibodies to JE in sera collected from residents of PNG showed antibodies were present in the middle Fly region of the Western Province in 1990 at a prevalence of 8%, and this level had risen to 26% in 1994. Antibodies were also present in the Gulf Province in 1995. No antibodies were found in samples from Milne Bay and New Ireland Provinces.

Hookworms : See Parasites above

Strongyloides : See Parasites above

Scabies : See Parasites above

Management of dogs and cats by local government

The control of domestic pets in cities and towns is a function of local government and usually becomes a duty of the health department. We obtained information from several projects that have assisted local government in this role. Euthanasia of unwanted pets is one of the options for control. In an analysis of the dogs and cats disposed of in Townsville we found about 2500 dogs and 2400 cats were killed in 1992, for dogs about 12% of the total estimated population.

An interesting intervention study looked at strategies to induce dog owners to reduce the number of dogs at large. A combination of animal control officers discussing problems with all dog owners and adopting a harder line with owners of dogs that were causing problems resulted in a significant reduction of dogs at large compared to discussion with owners only and no intervention. One of the assessment tools developed, "dogscan", allowed a quantitative estimate of dogs at large.

A survey of the attitudes to cats of residents of Magnetic Island, part of the city of Townsville, showed that most residents were strongly in favour of cats being registered and restrained at night.

Zoonotic diseases of dogs and cats in urban and remote communities

By examining dogs and cats disposed of by city councils in the Townsville region we have determined the prevalences of parasites and Salmonella. Dogs from Aboriginal communities prior to the commencement of parasite control programs had much higher levels of parasitism than dogs from urban areas.

DISEASES OF WILDLIFE

Diseases of cane toads (Bufo marinus)

Most of my research on this topic was carried out between 1988-1990. My emphasis now is on publication of results obtained during the Cane Toad Project at James Cook University.

Diseases of native amphibians

Expertise in amphibian disease gained during the Cane Toad Project has been used to investigate the role of infectious disease in the population crashes of several species of frogs in the rainforests of the Wet Tropics in North Queensland. Dr Lee Berger is currently doing a PhD on this topic and works mainly from the Australian Animal Health Laboratory, Geelong.

Diseases of macropods

My research on macropod diseases was largely done between 1978-1985, and concentrated particularly on the diseases of orphaned macropod joeys. Some recent publications have been based on work done during those years.