Craig Stephen

Cryptococcus gattii in Wildlife of Vancouver Island, British Columbia, Canada

Although Cryptococcus gattii has emerged as an important pathogen of humans and domestic animals on Vancouver Island, Canada since 1999; its distribution in regional wildlife species is largely unknown. Opportunistic sampling methods were employed to obtain nasal swabs for fungal culture from wild mammal species residing within the coastal Douglas fir biogeoclimatic zone on the southeast coast of the island. Samples were collected from 91 animals representing 14 species. Cryptococcus gattii was isolated from the nasal swabs of two eastern gray squirrels (Sciurus carolinensis) trapped in Duncan, British Columbia. The relative proportion of nasal colonization in wild mammal species is consistent with findings in domestic animals, suggesting that animals may be good indicators of environmental organisms.

Sub-clinical infection and asymptomatic carriage of Cryptococcus gattii in dogs and cats during an outbreak of cryptococcosis

Since 1999, Cryptococcus gattii has emerged as an important pathogen of humans and animals in British Columbia, Canada. Nasal swabs and serum samples were collected from dogs and cats residing within the Coastal Douglas Fir biogeoclimatic zone on Vancouver Island, where clinical cases have been reported. Deep and superficial nasal fungal cultures of 280 dogs and 94 cats identified four (4.3%) cats and three (1.1%) dogs with C. gattii serotype B in their nasal cavity. Serum samples collected from 266 dogs and 84 cats identified six (7.1%) cats and two (0.8%) dogs with a positive cryptococcal antigen titer. Overall cats were 4.4 times more likely than dogs to be positive on one or both tests. Identification of sub-clinical infection and nasal colonization is an important step in the characterization of the outbreak of clinical cryptococcosis on Vancouver Island.

Follow-up study of dogs and cats with asymptomatic Cryptococcus gattii infection or nasal colonization

The pathogenesis of Cryptococcus spp. infection following nasal colonization is unclear. This article reports follow-up data on a cohort of seven cats and five dogs identified in a previous study as sub-clinically infected with Cryptococcus spp. or colonized by C. gattii. Two cats progressed to clinical disease within four to six months of initial detection of antigenemia and nasal cavity colonization. The ten other animals remained asymptomatic but many were repeatedly positive on cryptococcal antigen testing or nasal fungal culture suggesting protracted infection or colonization. The results indicate that asymptomatically infected animals may clear the organism, remain sub-clinically infected or progress to clinical disease. Factors influencing the transition from exposure to disease require further investigation.

Wildlife parasites in a One Health world

One Health has gained a remarkable profile in the animal and public health communities, in part owing to the pressing issues of emerging infectious diseases of wildlife origin. Wildlife parasitology can offer insights into One Health, and likewise One Health can provide justification to study and act on wildlife parasites. But how do we decide which wildlife parasites are One Health issues? We explore toxoplasmosis in wildlife in the Canadian Arctic as an example of a parasite that poses a risk to human health, and that also has potential to adversely affect wildlife populations of conservation concern and importance for food security and cultural well-being. This One Health framework can help communities, researchers, and policymakers prioritize issues for action in a resource-limited world.

An evaluation of surface moribund salmon as indicators of seapen disease status

Abstract This observational study utilized modified mark and recapture techniques to examine the reliability of moribund fish caught at the surface of the water as indicators of the disease status of commercial salmon farms in British Columbia, Canada. The results indicate that the vast majority of fish captured at the surface are truly moribund, but that the pattern of disease in these fish can be significantly different from that seen in moribund fish not accessible to capture from the surface. In some cases, estimates of the proportional mortality attributed to specific disease categories differed by 30% between surface-caught fish and dead fish. The small number of fish caught at the surface makes it difficult to detect disease of low prevalence. In addition, the low proportion of total mortalities accessible to surface capture prior to their death makes extrapolation of disease data derived from surface samples to the entire pen tenuous. We conclude that samples of surface-catchable fish do not necessarily reveal the true disease pattern of a seapen and that future studies should be directed towards developing additional methods of disease monitoring and investigation on seafarms such as mortality surveys and behavioural observations.

Perspectives on Emerging Zoonotic Disease Research and Capacity Building in Canada

Zoonoses are fundamental determinants of community health. Preventing, identifying and managing these infections must be a central public health focus. Most current zoonoses research focuses on the interface of the pathogen and the clinically ill person, emphasizing microbial detection, mechanisms of pathogenicity and clinical intervention strategies, rather than examining the causes of emergence, persistence and spread of new zoonoses. There are gaps in the understanding of the animal determinants of emergence and the capacity to train highly qualified individuals; these are major obstacles to preventing new disease threats. The ability to predict the emergence of zoonoses and their resulting public health and societal impacts are hindered when insufficient effort is devoted to understanding zoonotic disease epidemiology, and when zoonoses are not examined in a manner that yields fundamental insight into their origin and spread. Emerging infectious disease research should rest on four pillars: enhanced communications across disciplinary and agency boundaries; the assessment and development of surveillance and disease detection tools; the examination of linkages between animal health determinants of human health outcomes; and finally, cross-disciplinary training and research. A national strategy to predict, prevent and manage emerging diseases must have a prominent and explicit role for veterinary and biological researchers. An integrated health approach would provide decision makers with a firmer foundation from which to build evidence-based disease prevention and control plans that involve complex human/animal/environmental systems, and would serve as the foundation to train and support the new cadre of individuals ultimately needed to maintain and apply research capacity in this area.

Surveillance for Cryptococcus gattii in horses of Vancouver Island, British Columbia, Canada

In the last decade Cryptococcus gattii has emerged as an important human and animal pathogen in southwestern British Columbia (BC), Canada. When the disease initially emerged it was identified in humans and multiple animal species on the east coast of Vancouver Island. From fall 2003 until summer 2004, active surveillance was initiated to look for horses exposed to or infected with the organism by performing nasal cultures and serum antigen testing in horses residing within 10 km of known areas of environmental reservoirs of the fungus. Surveillance efforts were facilitated by local equine practitioners who were also encouraged to report clinical cases. Nasal colonization was identified in four of the 260 horses tested but none had a serum cryptococcal antigen titer. All positive horses were from the same geographic area near Duncan, BC. During the study period, a single horse was diagnosed with systemic cryptococcosis and euthanized; clinical and post mortem information is described. As this organism continues to disseminate in the Pacific Northwest it is important for veterinarians to be familiar with the disease as early diagnosis may enable more effective treatment.

Obstacles to developing a multinational report card on antimicrobial resistance for Canada: an evidence-based review.

Many countries want to compare the results of their antimicrobial resistance programs to those of others nations to help gauge the effectiveness of their prevention and control practices. In our attempt to compare Canada with other nations, we encountered several challenges that must be addressed before meaningful multinational comparisons can be made. The fundamental barriers to comparison were the lack of shared targets for performance and predictive measures of success. Unique problems and policies within countries resulted in variations in goals, methods, pathogens, drugs, and priorities within and between jurisdictions. Other obstacles included: (1) lack of information on potential biases associated with different microbiological testing and sampling methods; (2) lack of information with which to conclude whether or not different programs examined comparable spectra of patients or outcomes; (3) inadequate description of the epidemiological rationale for sampling strategies; (4) use of aggregated national data that can hide regional or local variations; (5) rarity of studies designed explicitly for multinational comparison; and (6) lack of international agreement on methods, continuing education, and quality control needed to ensure program comparability. Comparison based on a countrys ability to meet its internal goals for antimicrobial resistance control may be a more informative basis for a report card than specific resistance or drug use rates.

Hiatal Hernia in a Harbor Porpoise (Phocoena phocoena)

We observed the displacement of the first compartment of the stomach through the diaphragmatic hiatus into the thoracic cavity in an immature harbor porpoise (Phocoena phocoena). This hiatal hernia, coupled with a severe pneumonia, contributed to the emaciation and death of the animal.

Can wildlife surveillance contribute to public health preparedness for climate change? A Canadian perspective

Early warning systems for climate change adaptation, preparedness and response will need to take into consideration the range of factors that can drive risk and vulnerability. There are no data from which to nominate the most effective, efficient and reliable wildlife health signals for public health planning, but there is growing opinion that wildlife health could signal public health vulnerability related to climate change. The objective of this commentary is to explore the potential for wildlife to contribute to climate change early warning for public health protection in Canada. Wildlife impact many determinants of human health through both direct and indirect mechanisms; several of which are strongly interconnected. There is a long history of wildlife serving as bio-sentinels for environmental pollutants and pathogens. Wildlife health could support public health threat detection, risk assessment and risk communication by detecting and tracking infectious and non-infectious hazards, being bio-sentinels of effects of new or changed hazards, providing biologically understandable information to motivate changes in personal risk behaviours and providing insights into new and unanticipated threats. Public health risk communication and strategic planning priorities for climate change could benefit from a wildlife health intelligence system that collects data on incidents of disease and hazard discovery as well as information on social and environmental conditions that affect risk perception and likelihoods of human exposure or harms.