Associations between frequencies of a susceptible TNF-alpha promoter allele and protective alpha-thalassaemias and malaria parasite incidence in Vanuatu

Walking backwards into the future: the need for a holistic evolutionary approach in Pacific health research

CONTEXT

The Pacific region has had a complex human history. It has been subject to multiple major human dispersal and colonisation events, including some of the earliest Out-of-Africa migrations, the so-called Austronesian expansion of people out of Island Southeast Asia, and the more recent arrival of Europeans. Despite models of island isolation, evidence suggests significant levels of interconnectedness that vary in direction and frequency over time. The Pacific Ocean covers a vast area and its islands provide an array of different physical environments with variable pathogen loads and subsistence opportunities. These diverse environments likely caused Pacific peoples to adapt (both genetically and culturally) in unique ways. Differences in genetic background, in combination with adaptation, likely affect their susceptibility to non-communicable diseases.

OBJECTIVES

Here we provide an overview of some of the key issues in the natural and human history of the Pacific region which are likely to impact human health. We argue that understanding the evolutionary and cultural history of Pacific peoples is essential for the generation of testable hypotheses surrounding potential causes of elevated disease susceptibility among Pacific peoples.

Implications of cytokine gene polymorphisms on the orchestration of the immune response: lessons learned from oral diseases

Over the past 10 years, a plethora of information concerning the influence of gene polymorphisms on cytokine expression has been made available in the literature. Significant contribution to this field has come from studies of oral diseases, one of the widest spread health problems in the world, affecting hundreds of millions worldwide. Here we will discuss the importance of studies of gene polymorphism towards the identification of susceptible groups or prognostic indicators of oral disease. Additionally, we will highlight the differences in data obtained from genetically diverse populations and review the application of cytokine gene polymorphisms studies in oral diseases in autoimmune processes and parasitic infections.

Population structure and gene flow of Anopheles farauti s.s. (Diptera: Culicidae) among ten sites on five islands of Vanuatu: implications for malaria control

The Anopheles punctulatus (Diptera: Culicidae) group is the main vector for malaria and Bancroftian filariasis in Vanuatu. Anopheles larvae were collected from 10 localities on five islands of Vanuatu during the 2004 dry season for species identification as well as for estimating population structure and gene flow within and among islands. Species identification was determined using polymerase chain reaction-restriction fragment length polymorphism analysis of the internal transcribed spacer 2 region. Population structure and gene flow were examined by sequencing a portion of the ND4/ND5 region of the mitochondrial genome. Only one species of the An. punctulatus group, An. farauti s.s., was identified, consistent with previous studies in Vanuatu. A nonrandom distribution of An. farauti s.s. lineages was observed with one cosmopolitan lineage shared by eight sites on all five islands and a preponderance of island-specific lineages (36/40), indicating the introduction of a single main lineage into Vanuatu followed by dispersal, diversification, and limited lineage exchange between islands. Network analysis suggests a possible second introduction of An. farauti s.s. into the northern islands of Gaua and Malekula. Gene flow was high on three of the five islands, whereas Tanna and Santo have significant population structure. Among islands, gene flow was limited, indicating active mosquito dispersal only over short distances and a paucity of passive human-mediated dispersal over long distances. Minimal risk of active dispersal among these islands indicates that vector control can be effectively initiated at the island level within the archipelago of Vanuatu.