Molecular identification of Sarcocystis wobeseri-like parasites in a new intermediate host species, the white-tailed sea eagle (Haliaeetus albicilla).

A reintroduced white-tailed sea eagle (Haliaeetus albicilla) in moderate body condition was found dead and submitted for post-mortem examination. There were no signs of disease on gross pathological examination. Histopathological examination however revealed the presence of encysted protozoan parasites in pectoral and cardiac muscle sections. Polymerase chain reaction amplification of extracted genomic DNA and sequencing of four regions: the 18S rDNA, 28S rDNA, internal transcribed spacer (ITS) 1, and RNA polymerase B (rpoB) loci, confirmed the presence of a Sarcocystis species in pectoral and cardiac muscle which appeared phylogenetically similar to Sarcocystis wobeseri. This is the first report of S. wobeseri-like infection in a white-tailed sea eagle revealing a new intermediate host species for this parasite.

Utilizing a combination of molecular and spatial tools to assess the effect of a public health intervention.

Until recently New Zealand had one of the highest rates of human campylobacteriosis reported by industrialized countries. Since the introduction of a range of control measures in the poultry production chain a reduction in human cases of around 50% has been observed nationwide. To inform risk managers a combination of spatial, temporal and molecular tools - including minimum spanning trees, risk surfaces, rarefaction analysis and dynamic source attribution modelling - was used in this study to formally evaluate the reduction in disease risk that occurred after the implementation of control measures in the poultry industry. Utilizing data from a sentinel surveillance site in the Manawatu region of New Zealand, our analyses demonstrated a reduction in disease risk attributable to a reduction in the number of poultry-associated campylobacteriosis cases. Before the implementation of interventions poultry-associated cases were more prevalent in urban than rural areas, whereas for ruminant-associated cases the reverse was evident. In addition to the overall reduction in prevalence, this study also showed a stronger intervention effect in urban areas where poultry sources were more dominant. Overall a combination of molecular and spatial tools has provided evidence that the interventions aimed at reducing Campylobacter contamination of poultry were successful in reducing poultry-associated disease and this will inform the development of future control strategies.

Molecular and spatial epidemiology of human campylobacteriosis: source association and genotype-related risk factors.

The epidemiology of human campylobacteriosis is complex but in recent years understanding of this disease has advanced considerably. Despite being a major public health concern in many countries, the presence of multiple hosts, genotypes and transmission pathways has made it difficult to identify and quantify the determinants of human infection and disease. This has delayed the development of successful intervention programmes for this disease in many countries including New Zealand, a country with a comparatively high, yet until recently poorly understood, rate of notified disease. This study investigated the epidemiology of Campylobacter jejuni at the genotype-level over a 3-year period between 2005 and 2008 using multilocus sequence typing. By combining epidemiological surveillance and population genetics, a dominant, internationally rare strain of C. jejuni (ST474) was identified, and most human cases (65.7%) were found to be caused by only seven different genotypes. Source association of genotypes was used to identify risk factors at the genotype-level through multivariable logistic regression and a spatial model. Poultry-associated cases were more likely to be found in urban areas compared to rural areas. In particular young children in rural areas had a higher risk of infection with ruminant strains than their urban counterparts. These findings provide important information for the implementation of pathway-specific control strategies.