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Prevalence of antibody to hepatitis A and hepatitis B viruses in selected populations of the South Pacific.

Five island populations representing the three major cultural groups of the South Pacific--Polynesia, Micronesia, Melanesia--were studied for prevalence of antibody to hepatitis A virus (anti-HAV) and of antibody to the core antigen of hepatitis B virus (anti-HBc). Sera were collected in the late 1950s and early 1960s, selected where possible for appropriate age and sex distributions, and were tested by radioimmunoassay. Rather marked differences in prevalence were observed. Anti-HBc patterns confirmed that HBV is endemic in the Pacific populations. Furthermore, the patterns differed somewhat from each other and did not correlate with ethnogeographic area. Prevalence of anti-HAV was high in all populations studied. A Unique pattern was found for the island of Ponape (Micronesia): In a Ponape population bled in 1963, anti-HAV was not detected in any individual under 20 years of age, but almost all individuals over that age were found to be seropositive. On testing a second group of sera collected in 1975, all individuals aged 14--21 years were found to be antibody positive, indicating that HAV had returned to Ponape sometime prior to 1975. There was no significant difference in the prevalence of HAV or HBV infection between males and females in any of the populations studied.

Adolescent↗

Genetic variation in a Pacific Island land snail: population history versus current drift and selection.

Previous studies of Partula land snails from the Society Islands, French Polynesia, have shown that there can be striking differences in shell shape, colour and banding pattern between nearby populations, even in the absence of any obvious geographical barriers to the movement of snails, or environmental gradients. Elsewhere, there may be relative uniformity over large distances. Analysis of a mitochondrial gene from Partula taeniata (Mörch) shows a similar pattern. The relative frequencies of two mitochondrial haplotypes change abruptly over small distances, seemingly independent of the environment. Although the transition roughly coincides with clines in the frequencies of some morphological characteristics, it appears to be unrelated to others. It is likely that many of the differences accumulated while populations were isolated from one another, through the effects of random genetic drift and selection. Isolation of populations may have occurred as a result of demographic changes, or during the process of colonization if occasional long-distance migrants establish populations ahead of the main invading front. Current genetic drift, even without restrictions to gene flow, may contribute to genetic patchiness on a small scale, although it is likely that conspicuous characteristics such as shell colours and banding patterns are also influenced by selection.

Animals↗

The T(1858) variant predisposing to the precore stop mutation correlates with one of two major genotype F hepatitis B virus clades.

The precore mutation G(1896)-->A occurs frequently in anti-HBe-positive carriers of HBsAg with T(1858) in the stem of the encapsidation signal. Hepatitis B virus (HBV) genotype F, considered an Amerindian genotype, subdivides into two clades and the precore mutation occurs in Central American F strains. To investigate the relationship between substitutions at position 1858 and these clades, the precore and small S genes of 48 strains of HBV genotype F were subjected to phylogenetic analyses. Isolates of one clade, formed mainly of Central American strains, all had T(1858) and Thr(45) in the S gene, whereas in the other clade, formed mainly of South American strains and one strain from Polynesia, all had C(1858) and Leu(45). The latter strain was related to strains from Venezuela and Colombia, supporting an Amerindian contribution to the Polynesian population. The position of the Polynesian strain in the phylogenetic tree indicates that the two clades have resulted from an early split, showing a high degree of genetic stability of the stem of the HBsAg encapsidation signal.

Central America↗

Mitochondrial genome variation and evolutionary history of Australian and New Guinean aborigines.

To study the evolutionary history of the Australian and New Guinean indigenous peoples, we analyzed 101 complete mitochondrial genomes including populations from Australia and New Guinea as well as from Africa, India, Europe, Asia, Melanesia, and Polynesia. The genetic diversity of the Australian mitochondrial sequences is remarkably high and is similar to that found across Asia. This is in contrast to the pattern seen in previously described Y-chromosome data where an Australia-specific haplotype was found at high frequency. The mitochondrial genome data indicate that Australia was colonized between 40 and 70 thousand years ago, either by a single migration from a heterogeneous source population or by multiple movements of smaller groups occurring over a period of time. Some Australian and New Guinea sequences form clades, suggesting the possibility of a joint colonization and/or admixture between the two regions.

Africa↗

High levels of sTNFR p75 and TNF alpha in dengue-infected patients.

Soluble forms of the two molecular species of the cell surface TNF receptors (sTNFR p55 and sTNFR p75) can reduce the activity of TNF alpha but they may also enhance its function by stabilizing the active TNF alpha oligomer. Considering the pathophysiological importance of sTNFR p75 for the regulation of the bioavailability of TNF alpha in the body, we determined the serum levels of sTNFR p75 and TNF alpha in 45 children and 28 adults with laboratory-confirmed dengue infection by using immunoassays. The serum samples were obtained from day 1 to day 15 after the onset of the disease during the 1989-1990 outbreak of dengue-3 in Tahiti, French Polynesia. The patients were clinically classified as having dengue hemorrhagic fever (DHF) and graded according to the criteria of the World Health Organization (WHO) into four grades from less severe (grade I) to severe (grade IV). The sera of both children and adult patients of all severity grades contained higher levels of sTNFR p75 than the sera of control subjects. Although high levels of TNF alpha were also detected in children and adults among grade I, II, III and IV patients, we found no correlation between sTNFR p75 and TNF alpha. We observed in adults a moderate elevation of sTNFR p75 and TNF alpha in sera compared with that observed in children. The raised levels of immunoreactive sTNFR p75 and TNF alpha in all clinical groups of dengue-infected patients strongly indicate activation of the TNF alpha system during dengue infection. The balance between sTNFR p75 and TNF alpha may be altered in dengue infection. Further investigations are needed to understand the role of sTNFR p75 and TNF alpha in the pathogenesis of DHF and to improve the management of dengue infection.

Adult↗

Molecular genetic studies of natives on Easter Island: evidence of an early European and Amerindian contribution to the Polynesian gene pool.

Most archaeological and linguistic evidence suggest a Polynesian origin of the population of Easter Island (Rapanui), and this view has been supported by the identification of Polynesian mitochondrial DNA (mtDNA) polymorphisms in prehistoric skeletal remains. However, some evidence of an early South American contact also exists (the sweet potato, bottle gourd etc.), but genetic studies have so far failed to show an early Amerindian contribution to the gene pool on Easter Island. To address this issue, we analyzed mtDNA and Y chromosome markers and performed high-resolution human leukocyte antigen (HLA) genotyping of DNA harvested from previously collected sera of 48 reputedly nonadmixed native Easter Islanders. All individuals carried mtDNA types and HLA alleles previously found in Polynesia, and most men carried Y chromosome markers of Polynesian origin, providing further evidence of a Polynesian origin of the population of Easter Island. A few individuals carried HLA alleles and/or Y chromosome markers of European origin. More interestingly, some individuals carried the HLA alleles A*0212 and B*3905, which are of typical Amerindian origin. The genealogy of some of the individuals carrying these non-Polynesian HLA alleles and their haplotypic backgrounds suggest an introduction into Easter Island in the early 1800s, or earlier. Thus, there may have been an early European and Amerindian contribution to the Polynesian gene pool of Easter Island.

American Indian or Alaska Native↗

Traces of human migrations in Helicobacter pylori populations.

Helicobacter pylori, a chronic gastric pathogen of human beings, can be divided into seven populations and subpopulations with distinct geographical distributions. These modern populations derive their gene pools from ancestral populations that arose in Africa, Central Asia, and East Asia. Subsequent spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas, the neolithic introduction of farming to Europe, the Bantu expansion within Africa, and the slave trade.

Africa↗

The immunodominant Brugia malayi paramyosin as a marker of current infection with Wuchereria bancrofti adult worms.

The full-length cDNA sequence encoding Brugia malayi L3 paramyosin has been isolated by immunoscreening a cDNA library with a mouse antiserum raised against Wuchereria bancrofti L3 infective larvae. A recombinant truncated form of paramyosin was expressed as a glutathione S-transferase fusion protein and used to evaluate humoral responses of adults from a W. bancrofti-endemic area in French Polynesia according to their parasitological status. Immunoglobulin G4 (IgG4) preferentially bound to paramyosin in W. bancrofti-parasitized individuals, in contrast to unparasitized individuals, who harbored neither microfilaria nor Og4C3 adult worm circulating antigen. Reduction of the anti-paramyosin IgG4 titer following combined chemotherapy with diethylcarbamazine and ivermectin was significantly correlated with a reduction in the adult worm burden. This indicates that the presence of paramyosin-reactive IgG4 is associated with the presence of parasites and that reduction can be used as an immunological marker for W. bancrofti clearance.

Adult↗

Prevalence of asthma among teenagers attending school in Tahiti.

The prevalence of asthma was studied in 6731 adolescents (average age 13.5 years, 48.6% boys) attending school in three towns of the isle of Tahiti, according to the ethnic origin of both parents. The pupils completed a self-administered questionnaire in class; 14.3% gave an affirmative answer to the question "Have you ever had attacks of asthma?" (cumulative prevalence). That prevalence was 11.4% in the Europeans, 13.7% in the Chinese, 13.8% in the Polynesians, 15.3% in those whose parents were "halves" (half-bred from Polynesians and Europeans), and 16.0% in the miscellaneous group (= other origins) (P less than 0.02). Asthma was significantly more frequent in boys only among the Europeans and those with one European parent. The results of this study confirm the high prevalence of asthma in French Polynesia found in a previous study. They give no evidence of a racial difference in prevalence but suggest an influence of environment.

Adolescent↗

Limited genetic diversity in polynesians reflected in the highly polymorphic 3'HVR alpha-globin gene marker.

Polynesians from five distinct island groups were studied with DNA probe alpha 3'HVR, a highly polymorphic VNTR (variable number of tandem repeats) minisatellite region associated with the alpha-globin gene cluster. Results showed a paucity of genetic heterozygosity together with clustering of alpha 3'HVR alleles with alpha-globin DNA haplotypes and alpha-globin gene rearrangements. This restricted diversity is consistent with population bottlenecks in the colonization of Polynesia.

Alleles↗

Blood pressure and culture. The contribution of cross-cultural comparisons to psychosomatics.

It is well known that mean blood pressure levels tend to be low in non-westernized tribal peoples and that these levels tend to rise, particularly in the older age groups, among persons of the same origins who come into more contact with modern Western life-styles. That tendency can be attributed to many factors - increased salt intake, increased obesity, acculturation anxiety, information overload, increased competitiveness, envious resentment, etc. Disentangling these various hypothesized factors is virtually impossible when studying patients or population samples from a single sociocultural group, but cross-cultural comparisons may under favorable circumstances permit some such disentangling. Using data from Micronesia, Polynesia, and East Africa, an attempt will be made to assess which types of psychological stress are most likely to conduce to hypertension, and how certain traditional cultures may have been reducing these stresses.

Adult↗

Control of the Aedes vectors of the dengue viruses and Wuchereria bancrofti: the French Polynesian experience.

In most of the 130 islands of French Polynesia, the stenotopic mosquitoes Aedes aegypti (the main local vector for the viruses causing dengue) and Aedes polynesiensis (the main local vector of Wuchereria bancrofti) share many breeding sites in water containers such as discarded cans, coconut shells, buckets and water-storage pots and drums. In addition to selective application of insecticides, non-polluting methods of controlling these mosquitoes have been evaluated during the last decade in two main ecological situations: (1) villages, where Aedes breeding sites are typically peridomestic; and (2) flooded burrows of land crabs, the major source of Ae. polynesiensis throughout the South Pacific region. Large-scale trials of biological control agents, such as mosquito fish (Gambusia affinis and Poecilia reticulata) and copepods (Mesocyclops aspericornis), and of integrated-control strategies have demonstrated the efficacy of certain techniques and control agents against the target Aedes populations in some village situations. Generally, mechanical methods (the use of layers of polystyrene beads against mosquito larvae and pupae, and screening against adult mosquitoes) were more efficient than use of the biological control agents. By integrating several methods of control, mosquito densities (as measured by human-bait collections and larval surveys) were reduced significantly compared with the results of concurrent sampling from untreated villages, and control remained effective for months after the interventions ceased. In land-crab burrows, the first attempts to control Aedes larvae used bacterial agents (Bacillus thuringiensis) and predatory copepods gave disappointing results. Mesocyclops aspericornis could be an effective control agent if the burrows were constantly flooded, but most burrows dry out and refill periodically, so copepod populations do not survive. As it proved difficult to reach all corners of the long sinuous burrows with any control agent, larvicidal (chlorpyrifos-methyl) baits were developed for foraging crabs to carry into their burrows. This novel technique proved to be effective and could become the method of choice for treating crab burrows. Further research is underway to find the optimum (biological or chemical) larvicidal ingredient for the crab bait. Despite the ecological and logistical challenges of controlling the Aedes vectors of the dengue viruses and W. bancrofti in so many scattered islands, the French Polynesian experience indicates that relatively simple methods can be integrated and applied effectively and economically. Operationally, however, success also depends on a strong political commitment and on at-risk communities that are sufficiently motivated to maintain a good level of Aedes control.

Adult↗

Prevalence of asthma in adolescents in various parts of France and its relationship to respiratory allergic manifestations.

Six studies have been carried out in France and French Polynesia to investigate the prevalence of asthma in adolescents attending secondary school and in Paris university students (68,179 subjects overall). All the studies used the same questionnaire, self-administered in the classroom, and interviews administered to students during the university's preventive medicine examination. An epidemiologic definition of asthma was considered an affirmative answer to the question, "Have you ever had attacks of asthma?" The prevalence of asthma ranged from 4 to 12 percent, most often higher in boys with a tendency to increase with age. The relationship between asthma and other allergic respiratory conditions was studied. Some recommendations are made here to improve the validity of data and to increase knowledge about the etiology of asthma.

Adolescent↗

Observations on the phylogeny of Opisthadena Linton, 1910 and related genera (Hemiuridae: Opisthadeninae) from Australian and French Polynesian waters.

Mitrostoma nototheniae Manter, 1954 is redescribed from Aplodactylus arctidens Richardson, off northern Tasmania. Opisthadena dimidia Linton, 1910 is reported from Kyphosus bigibbus Lacepède, Ningaloo, Western Australia, K. cinerascens (Forsskål), off Heron Island and Ningaloo, Western Australia, Kyphosus cornelii (Whitley), off Kalbarri, Western Australia, K. sydneyanus Günther, off Fremantle, Western Australia, K. sydneyanus ?, Ningaloo, Western Australia and K. vaigiensis (Quoy et Gaimard), off Heron and Lizard Islands, Queensland and Moorea, French Polynesia: measurements and an illustration are given. Neopisthadena habei Machida, 1980 is reported from K. sydneyanus off Fremantle, Western Australia: measurements and an illustration are given. Data derived from these specimens are used to recode a data-matrix developed by León-Règagnon et al. (1996), and the resultant tree produced is almost congruent with that of these authors. Our data indicate that this group of parasites is associated mostly with herbivorous hosts and that O. dimidia, while geographically widespread, is stenoxenic to the genus Kyphosus.

Animals↗

Cucullanus oceaniensis sp. n. (Nematoda: Cucullanidae) from Pacific eels (Anguilla spp.).

A new species of parasitic nematode, Cucullanus oceaniensis sp. n., is described from the intestine of the giant mottled eel Anguilla marmorata (type host) from Futuna Island (Wallis and Futuna Islands, Polynesia) and from A. marmorata and Anguilla sp. (cf. obscura) from Fiji Islands (Melanesia, South Pacific). The main distinguishing characteristics are the length of spicules (668-1,020 microm), situation of deirids (slightly anterior to the oesophago-intestinal junction) and the excretory pore (some distance posterior to the end of oesophagus), and the arrangement of caudal papillae in the male. It is the third known species of Cucullanus from Oceania and the first one reported from freshwater eels in the region of South Pacific. Cucullanus faliexae Morand et Rigby, 1998 is considered a junior synonym of Cucullanus australiensis Baylis, 1927.

Anguilla↗

Evaluation of insecticide impregnated baits for control of mosquito larvae in land crab burrows on French Polynesian atolls.

Land crab burrows are larval mosquito habitats of major significance in the Pacific region. They are constituted by a sinuous tunnel leading to a chamber in contact with the water table, where mosquito larvae proliferate. Controlling larvae in these sites is difficult, because the configuration of burrows prevents the use of standard techniques. An experiment was carried out in French Polynesia to control Aedes polynesiensis Marks and Culex spp. breeding in burrows of the land crab Cardisoma carnifex (Herbst). The technique was based on the crab's behavior, which involves the crab carrying food into its burrow. It was shown that appetizing baits impregnated with an insecticide were carried by crabs into the flooded chamber of their burrows. A field treatment of burrows was carried out by sowing insecticide impregnated baits on the ground. The treatment coverage was almost perfect and the easy implementation of the technique enabled large areas to be treated in a short time. The bait was developed by compacting various flours, which easily incorporate a large variety of insecticide formulations. Although the baits can be easily stocked, a reliable insecticide is still to be found. The results indicate that our technique could be a method of choice for treating crab burrows.

Aedes↗

Five new species of Pedibothrium (Tetraphyllidea: Onchobothriidae) from the tawny nurse shark, Nebrius ferrugineus, in the Pacific Ocean.

The spiral intestines of 7 Tawny nurse sharks (Nebrius ferrugineus; Rhincodontidae) from Australia and French Polynesia were examined for tapeworms. These sharks hosted 5 new species of Pedibothrium. The 5 species were prepared for light and scanning electron microscopy. Whereas 3 of the species exhibit the bipronged hooks typical of members of Pedibothrium, 1 species was found to possess tiny unipronged hooks or to lack some, or all, hooks, and all individuals of the fifth species appeared to lack bothridial hooks entirely. Nonetheless, the otherwise remarkable similarities between these species and the species of Pedibothrium bearing bipronged hooks were considered to be sufficient to justify the placement of these 2 species in this genus. All 5 species possess proglottid features typical of Pedibothrium, including a uterus that extends anteriorly only to the level of the cirrus sac and a cirrus sac that is bent anteriorly and is crossed by the vagina. All 5 species also exhibit uniloculated bothridia. Of particular note was the fact that all 5 species exhibit bladelike spinitrichs with elongated distal tips, a form of microthrix currently known only from species of Pedibothrium. As a consequence, these species were treated as possessing modified hooks or as having lost hooks. The diagnoses of Pedibothrium and Onchobothriidae were emended to include these species. Each of the 5 new species bears a strong resemblance to 1 or more species of Pedibothrium hosted by a species of rhincodontid shark other than N. ferrugineus. Much of Southwell's type and voucher material of Pedibothrium was located and used to verify the identity of Pedibothrium kerkhami and many of the hosts from which Southwell's material of Pedibothrium was collected. This material suggests that P. kerkhami parasitizes Stegostoma fasciatum and not N. ferrugineus.

Animals↗

Psychoactive substances of the South Seas: betel, kava and pituri.

Before white man brought his alcohol to the South Pacific, the indigenes were using many wild plants possessing psychoactive properties. The most prominent were betel in much of Melanesia, kava in much of Polynesia, and pituri in much of Australia. The use of each of these three drugs was widespread, institutionalised as a ritual and the occasion for extensive trade. Each was valued for its effect in reducing tension or in producing altered states of consciousness. Each was also capable of inducing intoxication. Since few physicians nowadays have had my opportunity to observe the use of all three of these substances, their main features are recalled here. Attention is paid to their traditional use and probable future use, to their pharmacological and clinical properties, and to their place in the zeitgeist of people and period. There is no indication that these substances will be espoused by the drug enthusiasts of the West as avidly as other ethno-psychopharmacological agents such as Peruvian coca leaf, the Indian hemp, the Asian poppy, or the American tobacco. The possibility, however, of some use in the West cannot be discounted.

Areca↗