The zoonotic parasite Trichinella is the causative agent of trichinellosis outbreaks in the circumpolar Arctic. Subsistence communities are particularly prone to trichinellosis due to traditional meat preparation methods and regional presence of a freeze-tolerant Trichinella species (Trichinella nativa). This study is the first application of a validated artificial digestion method in determining incidence of Trichinella sp. in Alaskan mammals. Infection incidence in pinniped species (Erignathus barbatus, Eumetopias jubatus, Odobenus rosmarus divergens, and Pusa hispida) was low, with only 1/57 ringed seals infected. Polymerase Chain Reaction assays indicate T. nativa as the only species present in northern Alaska. Analysis of an archived polar bear (Ursus maritimus) muscle sample shows freeze-tolerance and longevity for T. nativa to -20°C for 10 years and short-term freeze resistance to -80°C when morphology was used to determine presence of live larvae. However, larval motility suggests 0% survival. An approach that combines artificial digestion with PCR based species identification has excellent potential for Trichinella sp. detection and identification of archived tissues. Overall, Trichinella in Alaskan mammals, particularly marine mammals of subsistence importance, appears to be a minor problem. These modern diagnostic techniques provide accurate insight into the presence of Trichinella in the Alaskan marine environment.
BACKGROUND: Coalescent methods that use multi-locus sequence data are powerful tools for identifying putatively reproductively isolated lineages, though this approach has rarely been used for the study of microbial groups that are likely to harbor many unrecognized species. Among microbial symbionts, integrating genetic species delimitation methods with trait data that could indicate reproductive isolation, such as host specificity data, has rarely been used despite its potential to inform species limits. Here we test the ability of an integrative approach combining genetic and host specificity data to delimit species within the avian malaria parasite genus Leucocytozoon in central Alaska. RESULTS: We sequenced seven nuclear loci for 69 Leucocytozoon samples and used multiple species delimitation methods (GMYC and BPP models), tested for differences in host infection patterns among putative species based on 406 individual infections, and characterized parasite morphology. We found that cryptic morphology has masked a highly diverse Leucocytozoon assemblage, with most species delimitation methods recovering support for at least 21 separate species that occur sympatrically and have divergent host infection patterns. Reproductive isolation among putative species appears to have evolved despite low mtDNA divergence, and in one instance two Leucocytozoon cytb haplotypes that differed by a single base pair (~?0.2% divergence) were supported as separate species. However, there was no consistent association between mtDNA divergence and species limits. Among cytb haplotypes that differed by one to three base pairs we observed idiosyncratic patterns of nuclear and ecological divergence, with cytb haplotype pairs found to be either conspecific, reproductively isolated with no divergence in host specificity, or reproductively isolated with divergent patterns of host specialization. CONCLUSION: Integrating multi-locus genetic species delimitation methods and non-traditional ecological data types such as host specificity provide a novel view of the diversity of avian malaria parasites that has been missed previously using morphology and mtDNA barcodes. Species delimitation methods show that Leucocytozoon is highly species-rich in Alaska, and the genus is likely to harbor extraordinary species-level diversity worldwide. Integrating genetic and ecological data will be an important approach for understanding the diversity and evolutionary history of microbial symbionts moving forward.
The unprecedented rate of change in the Arctic climate is expected to have major impacts on the emergence of infectious diseases and host susceptibility to these diseases. It is predicted that malaria parasites will spread to both higher altitudes and latitudes with global warming. Here we show for the first time that avian Plasmodium transmission occurs in the North American Arctic. Over a latitudinal gradient in Alaska, from 61°N to 67°N, we collected blood samples of resident and migratory bird species. We found both residents and hatch year birds infected with Plasmodium as far north as 64°N, providing clear evidence that malaria transmission occurs in these climates. Based on our empirical data, we make the first projections of the habitat suitability for Plasmodium under a future-warming scenario in Alaska. These findings raise new concerns about the spread of malaria to naïve host populations.
Porifera have long been a reservoir for the discovery of bioactive compounds and drug discovery. Most research in the area has focused on sponges from tropical and temperate waters, but more recently the focus has shifted to the less accessible colder waters of the Antarctic and, to a lesser extent, the Arctic. The Antarctic region in particular has been a more popular location for natural products discovery and has provided promising candidates for drug development. This article reviews groups of bioactive compounds that have been isolated and reported from the southern reaches of the Arctic Circle, surveys the known sponge diversity present in the Arctic waters, and details a recent sponge collection by our group in the Aleutian Islands, Alaska. The collection has yielded previously undescribed sponge species along with primary activity against opportunistic infectious diseases, malaria, and HCV. The discovery of new sponge species and bioactive crude extracts gives optimism for the isolation of new bioactive compounds from a relatively unexplored source.
Francisella tularensis, a potential bioterrorism agent, is transmitted by arthropod vectors and causes tularemia in many mammals, including humans. Francisella novicida causes disease with similar pathology in mice. We show that F. novicida invades hemocyte-like cells of the SualB cell line derived from Anopheles gambiae and replicates vigorously within these cells. We used transposon knockouts of single genes of F. novicida to show that bacterial growth within these insect cells is dependent on virulence factors encoded in a bacterial pathogenicity island that has been linked to replication in mammalian macrophages. The virulence factors MglA, IglA, IglB, IglC, and IglD as well as PdpA and PdpB were necessary for efficient growth in insect cells, but PdpC and PdpD were not required. The SualB cell line presents a valuable model to study the interactions between this important pathogen and insect vectors.
In 1987, 1,957 new or reactivated cases of tuberculosis were reported in Canada, an 8.8% drop from 1986. This corresponds to an overall decline of almost 50% in Canada's tuberculosis rates over the past decade. This article examines tuberculosis rates by sex, age and province, and identifies four high risk groups. The first group, comprising North American Indians and Inuit, has a rate five to ten times higher than the Canadian population. Poor inner city residents have rates up to four times higher, and foreign-born Canadians up to three times higher. For all Canadians, risk increases with age, and thus the elderly comprise the fourth risk group. A fifth group, males aged 25 to 44 infected with Human Immunodeficiency Virus (HIV) and who later develop Acquired Immune Deficiency Syndrome (AIDS), has emerged in the United States although no increased risk is at yet seen in Canada.
The Tuberculosis Surveillance Project set out to gain community and health care worker support for and participation in the development and implementation of a tuberculosis control program which would address the high incidence of tuberculosis in Innu and Inuit communities in Labrador. The underlying principle of this project is that a tuberculosis control program must have the support of both the communities and the health care workers if it is to succeed. A three-person tuberculosis steering committee, with representation from the Innu Nation, the Labrador Inuit Association, and the Labrador Health Services Board, supervised initial tuberculosis data collection and analysis and workshop planning. Community Health Representatives, community physicians, and community nurses participated in a workshop to develop a tuberculosis protocol for the region. In addition, community tuberculosis control strategies were developed in workshops in each community in an effort to ensure community and health care worker support for the protocol and tuberculosis control in its broadest sense. This project illustrates how partnerships between communities and health care workers can be achieved. Future tuberculosis incidence rates will be used to evaluate the effectiveness of the partnership.