Hepatitis C virus (HCV) has become a global public health problem. Many studies have been conducted to identify risk factors for HCV infection. However, some of these studies reported inconsistent results. Using data collected from 11 methadone clinics, we fit both a non-spatial logistical regression and a geographically weighted logistic regression to analyse the association between HCV infection and some factors at the individual level. This study enrolled 5401 patients with 30·0% HCV infection prevalence. The non-spatial logistical regression found that injection history, drug rehabilitation history and senior high-school education or above were related to HCV infection; and being married was negatively associated with HCV infection. Using the spatial model, we found that Yi ethnicity was negatively related to HCV infection in 62·0% of townships, and being married was negatively associated with HCV infection in 81·0% of townships. Senior high-school education or above was positively associated with HCV infection in 55·2% of townships of the Yi Autonomous Prefecture. The spatial model offers better understanding of the geographical variations of the risk factors associated with HCV infection. The geographical variations may be useful for customizing intervention strategies for local regions for more efficient allocation of limited resources to control transmission of HCV.

Racially patterned disadvantage in Southern states, especially during the formative years of primary school, may contribute to enduring disparities in adult cognitive outcomes. Drawing on a lifecourse perspective, we examine whether state of school attendance affects cognitive outcomes in older adults and partially contributes to persistent racial disparities. Using data from older African American and white participants in the national Health and Retirement Study (HRS) and the New York based Washington Heights Inwood Cognitive Aging Project (WHICAP), we estimated age-and gender-adjusted multilevel models with random effects for states predicting years of education and cognitive outcomes (e.g., memory and vocabulary). We summarized the proportion of variation in outcomes attributable to state of school attendance and compared the magnitude of racial disparities across states. Among WHICAP African Americans, state of school attendance accounted for 9% of the variance in years of schooling, 6% of memory, and 12% of language. Among HRS African Americans, state of school attendance accounted for 13% of the variance in years of schooling and also contributed to variance in cognitive function (7%), memory (2%), and vocabulary (12%). Random slope models indicated state-level African American and white disparities in every Census region, with the largest racial differences in the South. State of school attendance may contribute to racial disparities in cognitive outcomes among older Americans. Despite tremendous within-state heterogeneity, state of school attendance also accounted for some variability in cognitive outcomes. Racial disparities in older Americans may reflect historical patterns of segregation and differential access to resources such as education. (JINS, 2015, 21, 677–687)

The response of Grapholita molesta (Busck) males to three-component sex pheromone blends containing a 100% ratio of the major sex pheromone component, (Z)-8-dodecenyl acetate and a 10% ratio of (Z)-8-dodecenol, but with varying ratios of (E)-8-dodecenyl acetate (0.4, 5.4, 10.4, 30.4, and 100.1% E-blends) was tested with populations in eight stone and pome fruit orchards in Europe, Asia, and North and South America. Traps baited with the 5.4% E-blend caught significantly more males than traps with any other blend with all populations. Significantly more males were caught in traps baited with the 10.4% E-blend than in traps with the remaining blends, except with the 0.4% E-blend in Turkey. Significant differences in male moth catches occurred between the other blends with the 0.4>30.4% E-blend, and the 30.4>100.1% E-blend. Male moth catches with the 100.1% E-blend only differed from the hexane control in Chile. No apparent differences were noted to these blends in populations collected from pome or stone fruits. Flight tunnel assays to synthetic blends with a subset of populations were similar to the field results, but the breadth of the most attractive E-blends was wider. Flight tunnel assays also demonstrated a high level of male–female cross-attraction among field-collected populations. Female gland extracts from field-collected populations did not show any significant variation in their three-component blends. The only exceptions in these assays were that long-term laboratory populations were less responsive and attractive, and produced different blend ratios of the two minor components than recently collected field populations.

Protection-based ant–plant mutualisms may vary in strength due to differences in ant rewards, abundance of protective ants and herbivory pressure. We investigated geographical and temporal variation in host plant traits and herbivory pressure at five sites spanning the distribution range of the myrmecophyte Humboldtia brunonis (Fabaceae) in the Indian Western Ghats. Southern sites had, on average, 2.4 times greater abundance of domatia-bearing individuals, 1.6 times greater extrafloral nectary numbers per leaf, 1.2 times larger extrafloral nectary sizes, 2.2 times greater extrafloral nectar (EFN) volumes and a two-fold increase in total amino acid and total sugar concentrations in EFN compared with northern sites. A strong protection-based mutualism with ants occurred at only one southern site where herbivory was highest, suggesting that investments in attracting ants correlate with anti-herbivore benefits gained from the presence of protective ants. Our results confirm a temporally stable north–south gradient in myrmecophytic traits in this ant-plant as several of these traits were re-sampled after a 5-y interval. However, the chemical composition of EFN varied at both spatial and short-term temporal scales suggesting that only repeated measurements of rewards such as EFN can reveal the real spectrum of trait variation in an ant–plant mutualistic system.

This paper examines the importance of environmental factors (mosquito pools and home foreclosures) in human West Nile virus (WNV) transmission in California and Colorado. The role of environmental factors is investigated by applying an instrumental variable technique to a spatial filtering random-effects negative binomial model to correct for both spatial autocorrelation and endogeneity. The results suggest that mosquito pools and home foreclosures are significant in explaining the prevalence of human WNV. An innovative aspect of this research is that it emphasizes the role of home foreclosures in WNV transmission and in the allocation of resources. Knowledge of the factors associated with WNV prevalence is crucial for abatement of future outbreaks. The results suggest that more resources should be allocated to areas that have a high number of home foreclosures and mosquito pools for surveillance and mitigation of the disease.

Observed field data from a range of geographically distinct human communities suggest a consistent non-linear relationship between prevalence and mean intensity of Ascaris lumbricoides infection. Utilizing the negative binomial distribution as a description of observed aggregation, maximum-likelihood analysis reveals that the degree of aggregation is a negative linear function of mean worm burden. The factors responsible for this relationship in human populations require further study but may involve some combination of (i) density-dependent reduction in worm numbers within individuals, (ii) density-dependent parasite-induced host mortality or (iii) self-treatment by heavily infected hosts. Variability in the degree of aggregation appears dependent on the level of infection in a community and independent of geographical differences in the host or parasite populations.

The small dotillid crab Ilyoplax pusilla builds an earthen structure, termed barricade, close to its neighbour's burrow. Barricades function for territorial defence by deterring invasion by neighbours. Comparison of the frequency of barricade building in the breeding season among 5 localities across the geographical range of I. pusilla, showed higher values at more northern localities. In two localities differing in the frequency of barricade building, the response of crabs to artificial barricades placed near their burrows was examined. The artificial barricade was less often broken and more often avoided in the locality with the higher frequency of barricades. These results suggest that the local difference in frequency of barricade building is correlated with a difference in how crabs respond to this earthen barrier.

The blue mussel, Mytilus edulis, and the Mediterranean mussel, Mytilus galloprovincialis, occur widely over much of northern Europe, and wherever they are sympatric they hybridize. The hybrid zone is large, ranging from western France to the north of Scotland, and is spatially complex, containing a mixture of pure, hybrid and introgressed individuals. Results from an Irish study in 1981, using partially diagnostic allozyme markers, indicated that mussels on the Irish Sea coast were solely M. edulis, but on Atlantic wave-exposed shores, and to a much lesser extent on wave-protected shores, mussels comprised an interbreeding mixture of M. edulis and M. galloprovincialis. In this study mussels were analysed from 20 locations on Irish coasts, using the Me15/16 nuclear DNA marker. The results showed a high frequency of M. galloprovincialis (0.378 ± 0.198) and hybrid (0.429 ± 0.175) genotypes, and correspondingly low frequencies of the M. edulis genotype (0.194 ± 0.107) at both exposed and sheltered locations on Atlantic coasts, indicating no apparent advantage for the M. edulis genotype at wave-protected sites. Mytilus galloprovincialis was virtually absent from the Irish Sea. Mussels in this area may be a self-recruiting population of M. edulis due to thermal front development at the northern and southern entrances to the Irish Sea in late spring, thereby preventing an influx of spring-spawned Mytilus larvae. The apparent change in the genetic composition of mussels on Atlantic coasts since the early 1980s could be related to climate change, or to aquaculture practice in Ireland whereby mussels from exposed shores are used to seed ropes in wave-protected bays and estuaries.

Waterfowl ingest lead shot because they confuse it with grit, but there has been limited study of differences among species and locations. The spatial and interspecific variation in the quantity and size composition of ingested grit and in the ingestion of lead shot by eight waterfowl species in the three main wintering areas in the western Mediterranean (Doñana, Ebro Delta and Camargue) was investigated. Variation in the mass of grit in the gizzard was related to bird species, whereas size composition of ingested grit was more closely related to locality and less to species. Birds with a large proportion of vegetation in their diets had more grit in the gizzard. Grit size composition was related to prevalence of lead shot ingestion. Thus, the quantity of grit in the gizzard is an attribute of species, and grit size composition (which largely determines the risk of ingestion of lead shot) is more affected by local conditions. This conclusion is supported by a meta-analysis of previous studies of the incidence of lead shot ingestion in 51 locations and 27 waterfowl species in North America and Europe. The prevalence of lead shot ingestion in a given waterbird species was highly variable between localities, and was not consistently different between dabbling, grazing and diving species.

Allozyme variation within and among populations of 3 species of the genus Lecithochirium (Trematoda: Hemiuridae) was studied by starch gel electrophoresis. In total, 19 loci were analysed in 7 populations. The level of genetic variability was relatively high in all populations. The percentage of polymorphic loci (0·95 criterion) observed per population varied from 21·0% to 55·5%, and expected heterozygosity levels varied from 0·082 to 0·197. All populations showed significant heterozygote deficiencies. In Lecithochirium fusiforme most of the deviations from Hardy–Weinberg proportions were within the populations and this species showed moderate population structuring (FIS=0·486, FST=0·142, Nm=1·51) and accordingly low intraspecific genetic distances (D=0·003 to 0·027). A significant lack of heterozygotes for several polymorphic loci was revealed in Lecithochirium rufoviride and Lecithochirium musculus. The most probable cause of the population genetic subdivision in L. rufoviride is the presence of at least 1 cryptic species in the populations studied. Although the lowest percentage of fixed genetic differences was that between L. fusiforme and L. musculus, two different algorithms for the construction of evolutionary trees on a matrix of genetic distances confirmed that L. fusiforme and L. rufoviride are phenetically the most closely related species.

The questing height (i.e. ambush height) of ticks on a plant plays an important role in host selection. To test the hypothesis that the questing height of ticks in a locality had adapted to the body size of the host in that locality, we examined the questing height of nymphs of the ticks, Haemaphysalis longicornis and H. mageshimaensis, at 7 locations in Japan. Sika deer, Cervus nippon, is the primary host of these ticks and there is considerable geographical variation in the body size of sika deer. Multiple regression analysis revealed that the questing height in the field was influenced by the height of the plants and by the body size of deer at a location. However, the questing height of ticks at some locations may have been constrained by the height of the plants and might not be the same as their intrinsic questing height. When ticks were placed in vertical glass tubes in the laboratory, the questing height of ticks from a locality was correlated with the mean body size of deer at that locality. Therefore, the prominent cue determining the questing height of H. longicornis and H. mageshimaensis seems to be the body size of the host deer.

The population of malaria-causing parasites is characterized by great genetic diversity. Knowledge of the polymorphism generation mechanism is a central issue for developing effective vaccines against malaria and understanding the parasite population structure. Plasmodium vivax genetic diversity has been explained in terms of two major factors: natural selection and intragenic recombination. A modular organization was found within P. vivax Duffy binding protein in the present work. Four Colombian isolates have identical sequences to Salvador-1 strain amongst dpb regions III–VI analysed, suggesting a high identity between Central and South American isolates. Geographically clustered sectors, corresponding to cysteine-rich regions (II and VI), show a high sequence diversity that could reflect a possible immune response evasion mechanism; both positive and negative selection were detected in these regions. In contrast, other dbp gene regions display a non-geographical clustering pattern, lower sequence diversity and predominant negative selective pressure. Recombination was homogeneously detected all along the molecule. These findings suggest that diversification vs. homogenizing forces, drive dbp gene evolution and determine its mosaic region organization.

Recent models argue that thermal environments are the major cause of ectotherm life-history clines. However, elevational clines in body size in the mountain dusky salamander Desmognathus ocoee (family Plethodontidae) shift from positive at hatching, to negative at metamorphosis to positive again as adults, and so are not consistent with this explanation. The clinal shift from hatching to metamorphosis was investigated by examining the clinal and seasonal feeding patterns of larval salamanders at high and low elevation sites in rockface and woodland habitats. Repeated cohort sampling was also used to examine clinal and seasonal patterns in body size and to estimate average growth rates. Larval growth in both rockface and woodland habitats was tightly correlated with feeding activity. Although temperature was found to vary between high and low elevation sites, the greatest growth occurred in a cold woodland habitat with a high elevation, and the lowest growth occurred in an adjacent rockface habitat. Because this difference in growth cannot be attributed to thermal differences, we conclude that local food resource levels are the predominant source of local differences in growth. These findings, clinal patterns of variation in other predatory salamanders, and experimental analyses in which both food and temperature are orthogonally manipulated, indicate that general models that single out temperature as the principle cause of ectotherm life-history clines should be viewed with caution.

Seven discrete cranial traits usually categorised as hyperostotic characters, the medial palatine canal, hypoglossal canal bridging, precondylar tubercle, condylus tertius, jugular foramen bridging, auditory exostosis, and mylohyoid bridging were investigated in 81 major human population samples from around the world. Significant asymmetric occurrences of the bilateral traits were detected in the medial palatine canal and jugular foramen bridging in several samples. Significant intertrait associations were found between some pairs of the traits, but not consistently across the large geographical samples. The auditory exostosis showed a predominant occurrence in males. With the exception of the auditory exostosis and mylohyoid bridging in a few samples, significant sex differences were slight. The frequency distributions of the traits (except for the auditory exostosis) showed some interregional clinality and intraregional discontinuity, suggesting that genetic drift could have contributed to the observed pattern of variation.

Four supernumerary ossicle variations—the ossicle at the lambda, the parietal notch bone, the asterionic bone, and the occipitomastoid bone—were examined for laterality differences, intertrait correlations, sex differences, and between group variations in the samples from around the world. Significant laterality differences were not detected in almost all samples. In some pairs of traits, significant association of occurrence were found. Several geographic samples were sexually dimorphic with respect to the asterionic bone and to a lesser extent for the parietal notch bone. East/Northeast Asians including the Arctic populations in general had lower frequencies of the 4 accessory ossicles. Australians, Melanesians and the majority of the New World peoples, on the other hand, generally had high frequencies. In the western hemisphere of the Old World, Subsaharan Africans had relatively high frequencies. Except for the ossicle at the lambda, the distribution pattern in incidence showed clinal variation from south to north. Any identifiable adaptive value related to environmental or subsistence factors may be expressed in such clinal variation. This may allow us to hypothesise that not only mechanical factors but a founder effect, genetic drift, and population structure could have been the underlying causes for interregional variation and possible clines in the incidences of the accessory ossicles.

The variation in frequency of the Inca bone was examined in major human populations around the world. The New World populations have generally high frequencies of the Inca bone, whereas lower frequencies occur in northeast Asians and Australians. Tibetan/Nepalese and Assam/Sikkim populations in northeast India have more Inca bones than do neighbouring populations. Among modern populations originally derived from eastern Asian population stock, the frequencies are highest in some of the marginal isolated groups. In Central and West Asia as well as in Europe, frequency of the Inca bone is relatively low. The incidence of the complete Inca bone is, moreover, very low in the western hemisphere of the Old World except for Subsaharan Africa. Subsaharan Africans show as a whole a second peak in the occurrence of the Inca bone. Geographical and ethnographical patterns of the frequency variation of the Inca bone found in this study indicate that the possible genetic background for the occurrence of this bone cannot be completely excluded. Relatively high frequencies of the Inca bone in Subsaharan Africans indicate that this trait is not a uniquely eastern Asian regional character.

The genetic population structures of the freshwater snail Bulinus globosus and its trematode parasite Schistosoma haematobium from 8 river sites in the Zimbabwean highveld were compared using randomly amplified DNA(RAPD) markers. There was significant variability between snail populations collected at different sites, but schistosome populations only showed differentiation at a wider geographical scale (between 2 non-connected river systems). For snails, genetic distance was better correlated with proximity along rivers than absolute geographical separation. In contrast, schistosome genetic distance was better correlated with absolute geographical separation than proximity along rivers. These results are consistent with different dispersal mechanisms for snails and schistosomes and the implications for host–parasite coevolution are discussed.

The frequency of the Os zygomaticum bipartitum was examined in major human populations around the world. Eastern Asians have a higher frequency of the bipartite zygomatic bone than any other geographical groups. The arctic peoples, Amerindians and the Oceanians, who all may have derived from eastern Asian population stocks, have a considerably low frequency of this trait. The frequency distribution from East/Southeast Asia to Africa and Europe through South/Central/West Asia suggests some clinality for the bipartite zygomatic bone. The second peak in the frequency is seen in Subsaharan Africa. The clinal variation with no identifiable regulation by subsistence patterns and environmental factors suggested a genetic background for the occurrence of the Os zygomaticum bipartitum.

Nation-wide data in Japan on the 112 sets of conjoined twins from fetal deaths and from postnatal deaths during 1979-1985 were analysed. Female conjoined twins accounted for 60% of cases. The incidence rate of conjoined twins remained Constant except in 1985. Overall incidence rate was 10 per million births. Maternal age effect was found in mothers over the age of 40, where the highest incidence rate was obtained. The incidence rate of conjoined twins increased with birth order. There was no seasonal variation in the time of conception.