Project description:Background:The oomycete Lagenidium giganteum forma caninum is an uncommon cause of severe dermal and subcutaneous infections in dogs with possible vascular invasion and other fatal sequelae. Infection within the central nervous system of affected dogs has not been previously reported. Case Description:A 6-year-old spayed female mixed-breed dog was evaluated at a referral institution with a 2-month history of suspected fungal infection in the region of the right mandibular lymph node that was refractory to surgical resection and empiric medical therapy. Physical examination identified a 6-cm fluctuant subcutaneous mass caudoventral to the ramus of the right mandible and a second firm mass in the region of the right caudal maxilla. Lesional punch biopsies were submitted for fungal culture and polymerase chain reaction (PCR), which subsequently identified L. giganteum forma caninum infection. Initial treatment consisted of anti-inflammatory doses of prednisone and hyperbaric oxygen therapy. Four weeks following initial evaluation, the patient was presented with progressive neurological signs consistent with a forebrain lesion. Magnetic resonance imaging revealed soft-tissue, contrast-enhancing lesions ventral to the calvarium adjacent to the site of original surgical resection and throughout the brain. Humane euthanasia was elected, and postmortem examination was consistent with the extension of local disease from the right masseter muscle into the right ventral calvarium. Postmortem DNA sequencing confirmed the identity of the organism as L. giganteum forma caninum. Conclusion:This is the first reported case of intracranial lagenidiosis in the dog. PCR distinguished this species from other Lagenidium species and from oomycetes of other genera, such as Pythium insidiosum and Paralagenidium karlingii. Regional extension of cutaneous lagenidiosis should therefore be considered in cases with concurrent or spontaneous neurologic disease.
Project description:Infections of mammals by species in the phylum Oomycota taxonomically and molecularly similar to known Lagenidium giganteum strains have increased. During 2013-2014, we conducted a phylogenetic study of 21 mammalian Lagenidium isolates; we found that 11 cannot be differentiated from L. giganteum strains that the US Environmental Protection Agency approved for biological control of mosquitoes; these strains were later unregistered and are no longer available. L. giganteum strains pathogenic to mammals formed a strongly supported clade with the biological control isolates, and both types experimentally infected mosquito larvae. However, the strains from mammals grew well at 25°C and 37°C, whereas the biological control strains developed normally at 25°C but poorly at higher temperatures. The emergence of heat-tolerant strains of L. giganteum pathogenic to lower animals and humans is of environmental and public health concern.
Project description:Recent advances in high throughput sequencing methodologies allow the opportunity to probe in depth the transcriptomes of organisms including N. caninum. In this project, we are using Illumina sequencing technology to analyze the transcriptome (RNA-Seq) of experimentally accessible stages (e.g. tachyzoites at different times points) of N. caninum NCLiv. The aim is to make transcriptional landscape maps at different time points at different life cycle stages of N. caninum and compare it with equivalent datasets from the closely related parasite Toxoplasma gondii