Research interests
My research interests fit broadly within the use of DNA-based tools to elucidate epidemiological or ecological aspects of species behaviour. For my PhD research I investigate the relative importance of tranmission routes of the protozoan parasite Toxoplasma gondii using a PCR-based assay in two species of small mammal. I was interested in the host genetic background of one of the populations I studied, Pipistrellus pipstrellus, and so I apprcoahed this using microsattelite markers. This study was the first of its kind in these species and is expected to be published in the next couple of months.
Toxoplasma is a member of the phylum Apicomplexa characterised by possessing an ‘apical complex’located in the anterior end of the organism which is used for host cell penetration. The phylum is an ancient group comprising of around 5000 parasitic species including significant pathogens of both humans and other animals. These pathogens include the causative agents of malaria, Plasmodium spp., and the common poultry disease coccidiosis caused by Eimeria spp. (Ajioka and Soldati, 2007). Both wild and domestic felids are the definitive hosts where the parasite completes its sexual cycle; however, Toxoplasma can potentially infect all warm-blooded mammals and birds. Toxoplasma is the causative agent of toxoplasmosis and is of significant medical and economic importance as it causes abortion and congenital disease in humans and domestic animals. By gaining a better understanding of the parasite's prevalence and distribution we may be able to gain insight into its overall epidemiology.
Toxoplasma is a fascinating parasite with a complex lifecycle and many aspects of its epidemiology are not understood. It was described over a hundred years ago and yet it still remains enigmatic which is why I will continue to follow this research even though my PhD seems already long behind me.
Toxoplasma is a member of the phylum Apicomplexa characterised by possessing an ‘apical complex’located in the anterior end of the organism which is used for host cell penetration. The phylum is an ancient group comprising of around 5000 parasitic species including significant pathogens of both humans and other animals. These pathogens include the causative agents of malaria, Plasmodium spp., and the common poultry disease coccidiosis caused by Eimeria spp. (Ajioka and Soldati, 2007). Both wild and domestic felids are the definitive hosts where the parasite completes its sexual cycle; however, Toxoplasma can potentially infect all warm-blooded mammals and birds. Toxoplasma is the causative agent of toxoplasmosis and is of significant medical and economic importance as it causes abortion and congenital disease in humans and domestic animals. By gaining a better understanding of the parasite's prevalence and distribution we may be able to gain insight into its overall epidemiology.
Toxoplasma is a fascinating parasite with a complex lifecycle and many aspects of its epidemiology are not understood. It was described over a hundred years ago and yet it still remains enigmatic which is why I will continue to follow this research even though my PhD seems already long behind me.
Human Toxoplasmosis
- Toxoplasmosis is a zoonotic disease
- Parasite of the cat (any member of Felidae)
- Produces highly infective oocysts in the intestinal epithelium of the cat
- Often found in high prevelances (~33%)
- Can infect all warm blooded mammals and birds
- Is thought primary source of infection is the cat
- Humans can become infected my ingesting undercooked meat
- When contracted congenitally causes abortion/miscarriage, ocular disease, hydrocephalus
- Morbidity and mortality in AIDs patients
- Parasite of the cat (any member of Felidae)
- Produces highly infective oocysts in the intestinal epithelium of the cat
- Often found in high prevelances (~33%)
- Can infect all warm blooded mammals and birds
- Is thought primary source of infection is the cat
- Humans can become infected my ingesting undercooked meat
- When contracted congenitally causes abortion/miscarriage, ocular disease, hydrocephalus
- Morbidity and mortality in AIDs patients
Molecular Epidmiology of Toxoplasma gondii (doctoral research)
Toxoplasma gondii is an obligate intracellular parasite which affects almost all species of mammals and has no known geographic boundary. It is of significant medical and economic importance as it causes abortion and congenital disease in humans and domestic animals. Three routes of transmission occur; ingestion of tissue cysts in the intermediate hosts, ingestion of oocysts shed by the feline definitive host into the environment and the transplacental crossing of tachyzoites from mother to foetus. The relative importance of each of these transmission routes in the epidemiology of the parasite has been of long debate, however it is widely accepted that the definitive host is the main source of infection. To investigate the relative importance of transmission routes in wildlife cycles, the prevalence of Toxoplasma gondiiwas investigated using Polymerase Chain Reaction (PCR) in woodmice, Apodemus sylvaticus, and British bats. The wild population of woodmice were obtained from an area largely free from cats which provided an opportunity to investigate vertical transmission in this population. Two species of British bats, Pipistrellus pipistrellus, and Pipistrellus pygmaeus, were also investigated using this method. All British bats are insectivorous and are not normally associated with cats, thus also providing
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and opportunity to investigate transmission cycles in these species. A subset of the bats comprising of the single species Pipistrellus pipistrellus (n= 71) where analysed using neutral markers to determine the population structure which was subsequently related to parasite infection. This was achieved using 11 polymorphic microsatellite loci and analysed using the programme STRUCTURE using the Bayesian assignment test.
Consistently high prevalences of Toxoplasma were recorded in the population of Apodemus sylvaticus (mean 40.78% ±6.71) over a ten year period. As woodmice are not normally carnivorous, and the area had very few cats present, this suggests congenital transmission being a significant route of propagation in this population. An overall prevalence of 10.39% (± 6.06%) was detected of the 77 bats, 71 Pipistrellus pipistrellus, and 6 Pipistrellus pygmaeus. The programme STRUCTURE suggested 4 distinct groups (K = 4), the largest of which contained 60 individuals. Therefore 84.5% of the individuals from this population are genetically related and are derived from the same interbreeding population. These data suggest that PCR is an effective tool for investigating Toxoplasma prevalences and that vertical transmission maybe more important that previously thought in wildlife cycles. |
Toxo in bats from Nicole Dodd