Vertebrate reservoirs of arboviruses are often infected with microÞlariae (MF). Laboratory studie... more Vertebrate reservoirs of arboviruses are often infected with microÞlariae (MF). Laboratory studies have shown that MF can enhance the infectivity of arboviruses to mosquitoes. Soon after being ingested, MF penetrate the mosquito midgut. If the host blood also contains virus (i.e., vertebrate is dually infected), penetrating MF may introduce virus into the hemocoel. This can transform otherwise virus-incompetent mosquito species into virus-competent species and simultaneously accelerate viral development, allowing mosquitoes to transmit virus sooner than normal. This phenomenon is termed microÞlarial enhancement of arboviral transmission. The prevalence of MF is very high in many passerine populations in North America. Therefore, we investigated if microÞlarial enhancement could have facilitated the establishment and rapid spread of West Nile virus (WNV) across the mid-western United States. Our investigations revealed that mosquitoes, WNV, and passerine MF do interact in nature because; 1) 17% of 54 common grackles (Quiscalus quiscula L.), 8% of 26 American robins (Turdus migratorius L.), and 33% of three eastern kingbirds (Tyrannus tyrannus L.) were concurrently microÞlaremic and seropositive to WNV; 2) feeding activities of mosquitoes overlapped temporally with the appearance of MF in the blood of common grackles; 3) mosquitoes fed on common grackles and American robins in nature; and 4) mosquito ingestion of two taxonomically distant species of passerine MF (i.e., Chandlerella quiscali and Eufilaria spp.) resulted in penetration of mosquito midguts. To estimate the theoretical effect that MF enhancement could have on WNV transmission in areas of high MF prevalence, vectorial capacity values were calculated for Culex mosquitoes feeding on common grackles, whereby MF enhancement was either invoked or ignored. For Cx. pipiens, vectorial capacity increased over three-fold when potential effects of MF were included in the calculations. For Cx. tarsalis, the effect was less (i.e., 1.4-fold increase). Closer attention should be paid to the potential of MF to enhance mosquito transmission of arboviruses.
Understanding how pathogens and parasites diversify through time and space is fundamental to pred... more Understanding how pathogens and parasites diversify through time and space is fundamental to predicting emerging infectious diseases. Here, we use biogeographic, coevolutionary and phylogenetic analyses to describe the origin, diversity, and distribution of avian malaria parasites in the most diverse avifauna on Earth. We first performed phylogenetic analyses using the mitochondrial cytochrome b (cyt b) gene to determine relationships among parasite lineages. Then, we estimated divergence times and reconstructed ancestral areas to uncover how landscape evolution has shaped the diversification of Parahaemoproteus and Plasmodium in Amazonia. Finally, we assessed the coevolutionary patterns of diversification in this host–parasite system to determine how coevolution may have influenced the contemporary diversity of avian malaria parasites and their distribution among Amazonian birds.Biogeographic analysis of 324 haemosporidian parasite lineages recovered from 4178 individual birds prov...
Vector-borne parasites are important ecological drivers influencing life-history evolution in bir... more Vector-borne parasites are important ecological drivers influencing life-history evolution in birds by increasing host mortality or susceptibility to new diseases. Therefore, understanding why vulnerability to infection varies within a host clade is a crucial task for conservation biology and for understanding macroecological life-history patterns. Here, we studied the relationship of avian life-history traits and climate on the prevalence ofPlasmodiumandParahaemoproteusparasites. We sampled 3569 individual birds belonging to 53 species of the family Thraupidae. Individuals were captured from 2007 to 2018 at 92 locations. We created 2 phylogenetic generalized least-squares models withPlasmodiumandParahaemoproteusprevalence as our response variables, and with the following predictor variables: climate PC1, climate PC2, body size, mixed-species flock participation, incubation period, migration, nest height, foraging height, forest cover, and diet. We found thatParahaemoproteusandPlasm...
The Proterodiplostomidae Dubois, 1936 is a relatively small family of diplostomoidean digeneans p... more The Proterodiplostomidae Dubois, 1936 is a relatively small family of diplostomoidean digeneans parasitising the intestines of reptilian hosts associated with freshwater environments in tropical and subtropical regions. The greatest diversity of proterodiplostomids is found in crocodilians, although some parasitise snakes and turtles. According to the most recent revision, the Proterodiplostomidae included 17 genera within 5 subfamilies. Despite the complex taxonomic structure of the family, availability of testable morphology-based phylogenetic hypotheses and ancient hosts, molecular phylogenetic analyses of the group were practically lacking. Herein, we use novel DNA sequence data of the nuclear lsrRNA gene and mitochondrial cox1 gene from a broad range of proterodiplostomid taxa obtained from crocodilian, fish, and snake hosts on four continents to test the monophyly of the family and evaluate the present morphology-based classification system of the Proterodiplostomidae in comparison with the This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:C7731 46C-F377-4C30-A73A-318D21119F9C. This article was published as an Online First article on the online publication date shown on this page. The article should be cited by using the doi number. This is the Version of Record.
Parasites with low host specificity (e.g. infecting a large diversity of host species) are of spe... more Parasites with low host specificity (e.g. infecting a large diversity of host species) are of special interest in disease ecology, as they are likely more capable of circumventing ecological or evolutionary barriers to infect new hosts than are specialist parasites. Yet for many parasites, host specificity is not fixed and can vary in response to environmental conditions. Using data on host associations for avian malaria parasites (Apicomplexa: Haemosporida), we develop a hierarchical model that quantifies this environmental dependency by partitioning host specificity variation into region-and parasite-level effects. Parasites were generally phylogenetic host specialists, infecting phylogenetically clustered subsets of available avian hosts. However, the magnitude of this specialization varied biogeographically, with parasites exhibiting higher host specificity in regions with more pronounced rainfall seasonality and wetter dry seasons. Recognizing the environmental dependency of parasite specialization can provide useful leverage for improving predictions of infection risk in response to global climate change.
Geographic variation in environmental conditions as well as host traits that promote parasite tra... more Geographic variation in environmental conditions as well as host traits that promote parasite transmission may impact infection rates and community assembly of vector‐transmitted parasites. Identifying the ecological, environmental and historical determinants of parasite distributions and diversity is therefore necessary to understand disease outbreaks under changing environments. Here, we identified the predictors and contributions of infection probability and phylogenetic diversity of Leucocytozoon (an avian blood parasite) at site and species levels across the New World. To explore spatial patterns in infection probability and lineage diversity for Leucocytozoon parasites, we surveyed 69 bird communities from Alaska to Patagonia. Using phylogenetic Bayesian hierarchical models and high‐resolution satellite remote‐sensing data, we determined the relative influence of climate, landscape, geography and host phylogeny on regional parasite community assembly. Infection rates and paras...
AimMacroecological analyses provide valuable insights into factors that influence how parasites a... more AimMacroecological analyses provide valuable insights into factors that influence how parasites are distributed across space and among hosts. Amid large uncertainties that arise when generalizing from local and regional findings, hierarchical approaches applied to global datasets are required to determine whether drivers of parasite infection patterns vary across scales. We assessed global patterns of haemosporidian infections across a broad diversity of avian host clades and zoogeographical realms to depict hotspots of prevalence and to identify possible underlying drivers.LocationGlobal.Time period1994–2019.Major taxa studiedAvian haemosporidian parasites (genera Plasmodium, Haemoproteus, Leucocytozoon and Parahaemoproteus).MethodsWe amalgamated infection data from 53,669 individual birds representing 2,445 species world‐wide. Spatio‐phylogenetic hierarchical Bayesian models were built to disentangle potential landscape, climatic and biotic drivers of infection probability while a...
Building Service Engineering Research and Technology, 2007
This paper presents empirical evidence and analysis suggesting significant heat loss from air mov... more This paper presents empirical evidence and analysis suggesting significant heat loss from air movement through cavities in party walls in masonry construction. The measurements have been made during the course of coheating tests undertaken as part of the Stamford Brook housing field trial (1). Direct measurements show the additional heat loss may amount to up to 30% of total heat loss in the dwellings tested, potentially making it the largest single contributor to heat loss in terraced dwellings built to the 2006 revision of the Building Regulations. The phenomenon of convective bypassing associated with masonry party walls was identified in the late 1970s in the course of the Twin Rivers Project (2,3) , albeit in a somewhat different construction from that used at Stamford Brook. A similar phenomenon was reported by Siviour (4) in
Background: Birds possess the most diverse assemblage of haemosporidian parasites; including thre... more Background: Birds possess the most diverse assemblage of haemosporidian parasites; including three genera, Plasmodium, Haemoproteus, and Leucocytozoon. Currently there are over 200 morphologically identified avian haemosporidian species, although true species richness is unknown due to great genetic diversity and insufficient sampling in highly diverse regions. Studies aimed at surveying haemosporidian diversity involve collecting and screening samples from hundreds to thousands of individuals. Currently, screening relies on microscopy and/or single or nested standard PCR. Although effective, these methods are time and resource consuming, and in the case of microscopy require substantial expertise. Here we report a newly developed real-time PCR protocol designed to quickly and reliably detect all three genera of avian haemosporidians in a single biochemical reaction. Methods: Using available DNA sequences from avian haemosporidians we designed primers R330F and R480RL, which flank a 182 base pair fragment of mitochondrial conserved rDNA. These primers were initially tested using real-time PCR on samples from Malawi, Africa, previously screened for avian haemosporidians using traditional nested PCR. Our real time protocol was further tested on 94 samples from the Cerrado biome of Brazil, previously screened using a single PCR assay for haemosporidian parasites. These samples were also amplified using modified nested PCR protocols, allowing for comparisons between the three different screening methods (single PCR, nested PCR, real-time PCR). Results: The real-time PCR protocol successfully identified all three genera of avian haemosporidians from both single and mixed infections previously detected from Malawi. There was no significant difference between the three different screening protocols used for the 94 samples from the Brazilian Cerrado (χ 2 = 0.3429, df = 2, P = 0.842). After proving effective, the real-time protocol was used to screen 2113 Brazilian samples, identifying 693 positive samples. Conclusions: Our real-time PCR assay proved as effective as two widely used molecular screening techniques, single PCR and nested PCR. However, the real-time protocol has the distinct advantage of detecting all three genera in a single reaction, which significantly increases efficiency by greatly decreasing screening time and cost. Our real-time PCR protocol is therefore a valuable tool in the quickly expanding field of avian haemosporidian research.
Determining the prevalence and local transmission dynamics of parasitic organisms are necessary t... more Determining the prevalence and local transmission dynamics of parasitic organisms are necessary to understand the ability of parasites to persist in host populations and disperse across regions, yet local transmission dynamics, diversity, and distribution of haemosporidian parasites remain poorly understood. We studied the prevalence, diversity, and distributions of avian haemosporidian parasites of the genera Plasmodium, Haemoproteus, and Leucocytozoon among resident and migratory birds in Serra do Mar, Brazil. Using 399 blood samples from 66 Atlantic Forest bird species, we determined the prevalence and molecular diversity of these pathogens across avian host species and described a new species of Haemoproteus. Our molecular and morphological study also revealed that migratory species were infected more than residents. However, vector infective stages (gametocytes) of Leucocytozoon spp., the most prevalent parasites found in the most abundant migrating host species in Serra do Mar...
Birds harbor an astonishing diversity of haemosporidian parasites belonging to the genera Haemopr... more Birds harbor an astonishing diversity of haemosporidian parasites belonging to the genera Haemoproteus, Leucocytozoon, and Plasmodium. Currently there are over 250 morphologically described avian haemosporidian species and 2828 unique lineages infecting virtually all avian clades and zoogeographic regions, except for Antarctica. Our report is based on PCR and microscopic screening of 1302 individual avian samples from Brazil to detect the underrepresented genus Leucocytozoon. This survey primarily focuses on passerine birds collected from Amazonia, Atlantic Rain Forest, and Pantanal. We also summarize studies conducted in Brazil that report haemosporidian prevalence using both microscopy and molecular tools and present for the first time a record of Leucocytozoon infecting an avian host population in Amazonia. Based on our finding, we suggest that high average temperatures may be constraining both the distribution and diversity of Leucocytozoon in lowland tropical South America.
SUMMARY Avian malaria is a vector transmitted disease caused by Plasmodium and recent studies sug... more SUMMARY Avian malaria is a vector transmitted disease caused by Plasmodium and recent studies suggest that variation in its prevalence across avian hosts is correlated with a variety of ecological traits. Here we examine the relationship between prevalence and diversity of Plasmodium lineages in southeastern Amazonia and: (1) host ecological traits (nest location, nest type, flocking behaviour and diet); (2) density and diversity of avian hosts; (3) abundance and diversity of mosquitoes; and (4) season. We used molecular methods to detect Plasmodium in blood samples from 675 individual birds of 120 species. Based on cytochrome b sequences, we recovered 89 lineages of Plasmodium from 136 infected individuals sampled across seven localities. Plasmodium prevalence was homogeneous over time (dry season and flooding season) and space, but heterogeneous among 51 avian host species. Variation in prevalence among bird species was not explained by avian ecological traits, density of avian ho...
Parasites of the genera Plasmodium and Haemoproteus (Apicomplexa: Haemosporida) are a diverse gro... more Parasites of the genera Plasmodium and Haemoproteus (Apicomplexa: Haemosporida) are a diverse group of pathogens that infect birds nearly worldwide. Despite their ubiquity, the ecological and evolutionary factors that shape the diversity and distribution of these protozoan parasites among avian communities and geographic regions are poorly understood. Based on a survey throughout the Neotropics of the haemosporidian parasites infecting manakins (Pipridae), a family of Passerine birds endemic to this region, we asked whether host relatedness, ecological similarity and geographic proximity structure parasite turnover between manakin species and local manakin assemblages. We used molecular methods to screen 1343 individuals of 30 manakin species for the presence of parasites. We found no significant correlations between manakin parasite lineage turnover and both manakin species turnover and geographic distance. Climate differences, species turnover in the larger bird community and para...
Avian host life history traits have been hypothesized to predict rates of infection by haemospori... more Avian host life history traits have been hypothesized to predict rates of infection by haemosporidian parasites. Using molecular techniques, we tested this hypothesis for parasites from three haemosporidian genera (Plasmodium, Haemoproteus, and Leucocytozoon) collected from a diverse sampling of birds in northern Malawi. We found that host life history traits were significantly associated with parasitism rates by all three parasite genera. Nest type and nest location predicted infection probability for all three parasite genera, whereas flocking behavior is an important predictor of Plasmodium and Haemoproteus infection and habitat is an important predictor of Leucocytozoon infection. Parasite prevalence was 79.1% across all individuals sampled, higher than that reported for comparable studies from any other region of the world. Parasite diversity was also exceptionally high, with 248 parasite cytochrome b lineages identified from 152 host species. A large proportion of Plasmodium, ...
The population dynamics of Plasmodium sporogony within mosquitoes consists of an early phase wher... more The population dynamics of Plasmodium sporogony within mosquitoes consists of an early phase where parasite abundance decreases during the transition from gametocyte to oocyst, an intermediate phase where parasite abundance remains static as oocysts, and a later phase where parasite abundance increases during the release of progeny sporozoites from oocysts. Sporogonic development is complete when sporozoites invade the mosquito salivary glands. The dynamics and efficiency of this developmental sequence were determined in laboratory strains of Anopheles dirus, Anopheles minimus and Anopheles sawadwongporni mosquitoes for Plasmodium vivax parasites circulating naturally in western Thailand. Mosquitoes were fed blood from 20 symptomatic Thai adults via membrane feeders. Absolute densities were estimated for macrogametocytes, round stages (= female gametes/zygotes), ookinetes, oocysts, haemolymph sporozoites and salivary gland sporozoites. From these census data, five aspects of populat...
West Nile virus (WNV) was first recovered in North Dakota near the city of Grand Forks in June 20... more West Nile virus (WNV) was first recovered in North Dakota near the city of Grand Forks in June 2002. During 2002, 2003, and 2004, we collected mosquitoes from Grand Forks using Mosquito Magnet traps and tested them for WNV. The seasonal abundance, species composition, and reproductive status of female mosquitoes were correlated with local environmental temperature and state surveillance data on WNV to determine the factors affecting local transmission of WNV. Over 90% of the mosquitoes collected were Aedes vexans, Ochlerotatus dorsalis, and Culex tarsalis, but WNV was detected only in Cx. tarsalis. Average summertime temperatures and relative abundance of mosquitoes were highest in 2002 but no WNV-positive mosquitoes were detected until the following summer. In 2003, nulliparous Cx. tarsalis appeared in mid-June (first summer brood), and parous Cx. tarsalis appeared in mid-July. The first WNV-positive pool occurred 21 July, and minimum daily infections rates increased thereafter until 27 August. The minimum infection rate (MIR) for Cx. tarsalis during the season was 5.7 infected mosquitoes per 1,000 tested, with the highest infection rates occurring at the end of the season as Cx. tarsalis populations started to decline. Mid-to-late August was identified as the period of highest risk for being bitten by a WNV-infected mosquito in Grand Forks during 2003. In 2004, viral activity in Grand Forks was low, due to very cool temperatures throughout the summer. To examine the genetic diversity of the 2003 WNV isolates from Grand Forks, we sequenced a 366-nucleotide region of the capsid and premembrane gene. Thirteen (46%) of the 28 WNV isolates contained at least one nucleotide substitution when compared to the homologous region of the progenitor WN NY-99 strain, and seven of these 13 substitutions coded for amino acid changes. Thus, WNV is established in North Dakota, it appears to be evolving and it is vectored primarily by Cx. tarsalis.
West Nile virus (WNV) epizootiology was monitored from 2002 through 2005 in the area surrounding ... more West Nile virus (WNV) epizootiology was monitored from 2002 through 2005 in the area surrounding Grand Forks, North Dakota. Mosquitoes were tested for infection, and birds were surveyed for antibodies. In 2003, WNV was epidemic; in 2004, cool temperatures precluded WNV amplification; and in 2005, immunity in passerines decreased, but did not preclude, WNV amplification.
Two new species of Camallanus are described from Australian freshwater turtles. Camallanus beveri... more Two new species of Camallanus are described from Australian freshwater turtles. Camallanus beveridgei sp. nov. is reported from Elseya dentata in Northern Territory. It differs from other species of the genus parasitic in turtles by several characters including the shape of the median ridge in the buccal capsule and the position of the anterior pair of caudal papillae in males.
Vertebrate reservoirs of arboviruses are often infected with microÞlariae (MF). Laboratory studie... more Vertebrate reservoirs of arboviruses are often infected with microÞlariae (MF). Laboratory studies have shown that MF can enhance the infectivity of arboviruses to mosquitoes. Soon after being ingested, MF penetrate the mosquito midgut. If the host blood also contains virus (i.e., vertebrate is dually infected), penetrating MF may introduce virus into the hemocoel. This can transform otherwise virus-incompetent mosquito species into virus-competent species and simultaneously accelerate viral development, allowing mosquitoes to transmit virus sooner than normal. This phenomenon is termed microÞlarial enhancement of arboviral transmission. The prevalence of MF is very high in many passerine populations in North America. Therefore, we investigated if microÞlarial enhancement could have facilitated the establishment and rapid spread of West Nile virus (WNV) across the mid-western United States. Our investigations revealed that mosquitoes, WNV, and passerine MF do interact in nature because; 1) 17% of 54 common grackles (Quiscalus quiscula L.), 8% of 26 American robins (Turdus migratorius L.), and 33% of three eastern kingbirds (Tyrannus tyrannus L.) were concurrently microÞlaremic and seropositive to WNV; 2) feeding activities of mosquitoes overlapped temporally with the appearance of MF in the blood of common grackles; 3) mosquitoes fed on common grackles and American robins in nature; and 4) mosquito ingestion of two taxonomically distant species of passerine MF (i.e., Chandlerella quiscali and Eufilaria spp.) resulted in penetration of mosquito midguts. To estimate the theoretical effect that MF enhancement could have on WNV transmission in areas of high MF prevalence, vectorial capacity values were calculated for Culex mosquitoes feeding on common grackles, whereby MF enhancement was either invoked or ignored. For Cx. pipiens, vectorial capacity increased over three-fold when potential effects of MF were included in the calculations. For Cx. tarsalis, the effect was less (i.e., 1.4-fold increase). Closer attention should be paid to the potential of MF to enhance mosquito transmission of arboviruses.
Understanding how pathogens and parasites diversify through time and space is fundamental to pred... more Understanding how pathogens and parasites diversify through time and space is fundamental to predicting emerging infectious diseases. Here, we use biogeographic, coevolutionary and phylogenetic analyses to describe the origin, diversity, and distribution of avian malaria parasites in the most diverse avifauna on Earth. We first performed phylogenetic analyses using the mitochondrial cytochrome b (cyt b) gene to determine relationships among parasite lineages. Then, we estimated divergence times and reconstructed ancestral areas to uncover how landscape evolution has shaped the diversification of Parahaemoproteus and Plasmodium in Amazonia. Finally, we assessed the coevolutionary patterns of diversification in this host–parasite system to determine how coevolution may have influenced the contemporary diversity of avian malaria parasites and their distribution among Amazonian birds.Biogeographic analysis of 324 haemosporidian parasite lineages recovered from 4178 individual birds prov...
Vector-borne parasites are important ecological drivers influencing life-history evolution in bir... more Vector-borne parasites are important ecological drivers influencing life-history evolution in birds by increasing host mortality or susceptibility to new diseases. Therefore, understanding why vulnerability to infection varies within a host clade is a crucial task for conservation biology and for understanding macroecological life-history patterns. Here, we studied the relationship of avian life-history traits and climate on the prevalence ofPlasmodiumandParahaemoproteusparasites. We sampled 3569 individual birds belonging to 53 species of the family Thraupidae. Individuals were captured from 2007 to 2018 at 92 locations. We created 2 phylogenetic generalized least-squares models withPlasmodiumandParahaemoproteusprevalence as our response variables, and with the following predictor variables: climate PC1, climate PC2, body size, mixed-species flock participation, incubation period, migration, nest height, foraging height, forest cover, and diet. We found thatParahaemoproteusandPlasm...
The Proterodiplostomidae Dubois, 1936 is a relatively small family of diplostomoidean digeneans p... more The Proterodiplostomidae Dubois, 1936 is a relatively small family of diplostomoidean digeneans parasitising the intestines of reptilian hosts associated with freshwater environments in tropical and subtropical regions. The greatest diversity of proterodiplostomids is found in crocodilians, although some parasitise snakes and turtles. According to the most recent revision, the Proterodiplostomidae included 17 genera within 5 subfamilies. Despite the complex taxonomic structure of the family, availability of testable morphology-based phylogenetic hypotheses and ancient hosts, molecular phylogenetic analyses of the group were practically lacking. Herein, we use novel DNA sequence data of the nuclear lsrRNA gene and mitochondrial cox1 gene from a broad range of proterodiplostomid taxa obtained from crocodilian, fish, and snake hosts on four continents to test the monophyly of the family and evaluate the present morphology-based classification system of the Proterodiplostomidae in comparison with the This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:C7731 46C-F377-4C30-A73A-318D21119F9C. This article was published as an Online First article on the online publication date shown on this page. The article should be cited by using the doi number. This is the Version of Record.
Parasites with low host specificity (e.g. infecting a large diversity of host species) are of spe... more Parasites with low host specificity (e.g. infecting a large diversity of host species) are of special interest in disease ecology, as they are likely more capable of circumventing ecological or evolutionary barriers to infect new hosts than are specialist parasites. Yet for many parasites, host specificity is not fixed and can vary in response to environmental conditions. Using data on host associations for avian malaria parasites (Apicomplexa: Haemosporida), we develop a hierarchical model that quantifies this environmental dependency by partitioning host specificity variation into region-and parasite-level effects. Parasites were generally phylogenetic host specialists, infecting phylogenetically clustered subsets of available avian hosts. However, the magnitude of this specialization varied biogeographically, with parasites exhibiting higher host specificity in regions with more pronounced rainfall seasonality and wetter dry seasons. Recognizing the environmental dependency of parasite specialization can provide useful leverage for improving predictions of infection risk in response to global climate change.
Geographic variation in environmental conditions as well as host traits that promote parasite tra... more Geographic variation in environmental conditions as well as host traits that promote parasite transmission may impact infection rates and community assembly of vector‐transmitted parasites. Identifying the ecological, environmental and historical determinants of parasite distributions and diversity is therefore necessary to understand disease outbreaks under changing environments. Here, we identified the predictors and contributions of infection probability and phylogenetic diversity of Leucocytozoon (an avian blood parasite) at site and species levels across the New World. To explore spatial patterns in infection probability and lineage diversity for Leucocytozoon parasites, we surveyed 69 bird communities from Alaska to Patagonia. Using phylogenetic Bayesian hierarchical models and high‐resolution satellite remote‐sensing data, we determined the relative influence of climate, landscape, geography and host phylogeny on regional parasite community assembly. Infection rates and paras...
AimMacroecological analyses provide valuable insights into factors that influence how parasites a... more AimMacroecological analyses provide valuable insights into factors that influence how parasites are distributed across space and among hosts. Amid large uncertainties that arise when generalizing from local and regional findings, hierarchical approaches applied to global datasets are required to determine whether drivers of parasite infection patterns vary across scales. We assessed global patterns of haemosporidian infections across a broad diversity of avian host clades and zoogeographical realms to depict hotspots of prevalence and to identify possible underlying drivers.LocationGlobal.Time period1994–2019.Major taxa studiedAvian haemosporidian parasites (genera Plasmodium, Haemoproteus, Leucocytozoon and Parahaemoproteus).MethodsWe amalgamated infection data from 53,669 individual birds representing 2,445 species world‐wide. Spatio‐phylogenetic hierarchical Bayesian models were built to disentangle potential landscape, climatic and biotic drivers of infection probability while a...
Building Service Engineering Research and Technology, 2007
This paper presents empirical evidence and analysis suggesting significant heat loss from air mov... more This paper presents empirical evidence and analysis suggesting significant heat loss from air movement through cavities in party walls in masonry construction. The measurements have been made during the course of coheating tests undertaken as part of the Stamford Brook housing field trial (1). Direct measurements show the additional heat loss may amount to up to 30% of total heat loss in the dwellings tested, potentially making it the largest single contributor to heat loss in terraced dwellings built to the 2006 revision of the Building Regulations. The phenomenon of convective bypassing associated with masonry party walls was identified in the late 1970s in the course of the Twin Rivers Project (2,3) , albeit in a somewhat different construction from that used at Stamford Brook. A similar phenomenon was reported by Siviour (4) in
Background: Birds possess the most diverse assemblage of haemosporidian parasites; including thre... more Background: Birds possess the most diverse assemblage of haemosporidian parasites; including three genera, Plasmodium, Haemoproteus, and Leucocytozoon. Currently there are over 200 morphologically identified avian haemosporidian species, although true species richness is unknown due to great genetic diversity and insufficient sampling in highly diverse regions. Studies aimed at surveying haemosporidian diversity involve collecting and screening samples from hundreds to thousands of individuals. Currently, screening relies on microscopy and/or single or nested standard PCR. Although effective, these methods are time and resource consuming, and in the case of microscopy require substantial expertise. Here we report a newly developed real-time PCR protocol designed to quickly and reliably detect all three genera of avian haemosporidians in a single biochemical reaction. Methods: Using available DNA sequences from avian haemosporidians we designed primers R330F and R480RL, which flank a 182 base pair fragment of mitochondrial conserved rDNA. These primers were initially tested using real-time PCR on samples from Malawi, Africa, previously screened for avian haemosporidians using traditional nested PCR. Our real time protocol was further tested on 94 samples from the Cerrado biome of Brazil, previously screened using a single PCR assay for haemosporidian parasites. These samples were also amplified using modified nested PCR protocols, allowing for comparisons between the three different screening methods (single PCR, nested PCR, real-time PCR). Results: The real-time PCR protocol successfully identified all three genera of avian haemosporidians from both single and mixed infections previously detected from Malawi. There was no significant difference between the three different screening protocols used for the 94 samples from the Brazilian Cerrado (χ 2 = 0.3429, df = 2, P = 0.842). After proving effective, the real-time protocol was used to screen 2113 Brazilian samples, identifying 693 positive samples. Conclusions: Our real-time PCR assay proved as effective as two widely used molecular screening techniques, single PCR and nested PCR. However, the real-time protocol has the distinct advantage of detecting all three genera in a single reaction, which significantly increases efficiency by greatly decreasing screening time and cost. Our real-time PCR protocol is therefore a valuable tool in the quickly expanding field of avian haemosporidian research.
Determining the prevalence and local transmission dynamics of parasitic organisms are necessary t... more Determining the prevalence and local transmission dynamics of parasitic organisms are necessary to understand the ability of parasites to persist in host populations and disperse across regions, yet local transmission dynamics, diversity, and distribution of haemosporidian parasites remain poorly understood. We studied the prevalence, diversity, and distributions of avian haemosporidian parasites of the genera Plasmodium, Haemoproteus, and Leucocytozoon among resident and migratory birds in Serra do Mar, Brazil. Using 399 blood samples from 66 Atlantic Forest bird species, we determined the prevalence and molecular diversity of these pathogens across avian host species and described a new species of Haemoproteus. Our molecular and morphological study also revealed that migratory species were infected more than residents. However, vector infective stages (gametocytes) of Leucocytozoon spp., the most prevalent parasites found in the most abundant migrating host species in Serra do Mar...
Birds harbor an astonishing diversity of haemosporidian parasites belonging to the genera Haemopr... more Birds harbor an astonishing diversity of haemosporidian parasites belonging to the genera Haemoproteus, Leucocytozoon, and Plasmodium. Currently there are over 250 morphologically described avian haemosporidian species and 2828 unique lineages infecting virtually all avian clades and zoogeographic regions, except for Antarctica. Our report is based on PCR and microscopic screening of 1302 individual avian samples from Brazil to detect the underrepresented genus Leucocytozoon. This survey primarily focuses on passerine birds collected from Amazonia, Atlantic Rain Forest, and Pantanal. We also summarize studies conducted in Brazil that report haemosporidian prevalence using both microscopy and molecular tools and present for the first time a record of Leucocytozoon infecting an avian host population in Amazonia. Based on our finding, we suggest that high average temperatures may be constraining both the distribution and diversity of Leucocytozoon in lowland tropical South America.
SUMMARY Avian malaria is a vector transmitted disease caused by Plasmodium and recent studies sug... more SUMMARY Avian malaria is a vector transmitted disease caused by Plasmodium and recent studies suggest that variation in its prevalence across avian hosts is correlated with a variety of ecological traits. Here we examine the relationship between prevalence and diversity of Plasmodium lineages in southeastern Amazonia and: (1) host ecological traits (nest location, nest type, flocking behaviour and diet); (2) density and diversity of avian hosts; (3) abundance and diversity of mosquitoes; and (4) season. We used molecular methods to detect Plasmodium in blood samples from 675 individual birds of 120 species. Based on cytochrome b sequences, we recovered 89 lineages of Plasmodium from 136 infected individuals sampled across seven localities. Plasmodium prevalence was homogeneous over time (dry season and flooding season) and space, but heterogeneous among 51 avian host species. Variation in prevalence among bird species was not explained by avian ecological traits, density of avian ho...
Parasites of the genera Plasmodium and Haemoproteus (Apicomplexa: Haemosporida) are a diverse gro... more Parasites of the genera Plasmodium and Haemoproteus (Apicomplexa: Haemosporida) are a diverse group of pathogens that infect birds nearly worldwide. Despite their ubiquity, the ecological and evolutionary factors that shape the diversity and distribution of these protozoan parasites among avian communities and geographic regions are poorly understood. Based on a survey throughout the Neotropics of the haemosporidian parasites infecting manakins (Pipridae), a family of Passerine birds endemic to this region, we asked whether host relatedness, ecological similarity and geographic proximity structure parasite turnover between manakin species and local manakin assemblages. We used molecular methods to screen 1343 individuals of 30 manakin species for the presence of parasites. We found no significant correlations between manakin parasite lineage turnover and both manakin species turnover and geographic distance. Climate differences, species turnover in the larger bird community and para...
Avian host life history traits have been hypothesized to predict rates of infection by haemospori... more Avian host life history traits have been hypothesized to predict rates of infection by haemosporidian parasites. Using molecular techniques, we tested this hypothesis for parasites from three haemosporidian genera (Plasmodium, Haemoproteus, and Leucocytozoon) collected from a diverse sampling of birds in northern Malawi. We found that host life history traits were significantly associated with parasitism rates by all three parasite genera. Nest type and nest location predicted infection probability for all three parasite genera, whereas flocking behavior is an important predictor of Plasmodium and Haemoproteus infection and habitat is an important predictor of Leucocytozoon infection. Parasite prevalence was 79.1% across all individuals sampled, higher than that reported for comparable studies from any other region of the world. Parasite diversity was also exceptionally high, with 248 parasite cytochrome b lineages identified from 152 host species. A large proportion of Plasmodium, ...
The population dynamics of Plasmodium sporogony within mosquitoes consists of an early phase wher... more The population dynamics of Plasmodium sporogony within mosquitoes consists of an early phase where parasite abundance decreases during the transition from gametocyte to oocyst, an intermediate phase where parasite abundance remains static as oocysts, and a later phase where parasite abundance increases during the release of progeny sporozoites from oocysts. Sporogonic development is complete when sporozoites invade the mosquito salivary glands. The dynamics and efficiency of this developmental sequence were determined in laboratory strains of Anopheles dirus, Anopheles minimus and Anopheles sawadwongporni mosquitoes for Plasmodium vivax parasites circulating naturally in western Thailand. Mosquitoes were fed blood from 20 symptomatic Thai adults via membrane feeders. Absolute densities were estimated for macrogametocytes, round stages (= female gametes/zygotes), ookinetes, oocysts, haemolymph sporozoites and salivary gland sporozoites. From these census data, five aspects of populat...
West Nile virus (WNV) was first recovered in North Dakota near the city of Grand Forks in June 20... more West Nile virus (WNV) was first recovered in North Dakota near the city of Grand Forks in June 2002. During 2002, 2003, and 2004, we collected mosquitoes from Grand Forks using Mosquito Magnet traps and tested them for WNV. The seasonal abundance, species composition, and reproductive status of female mosquitoes were correlated with local environmental temperature and state surveillance data on WNV to determine the factors affecting local transmission of WNV. Over 90% of the mosquitoes collected were Aedes vexans, Ochlerotatus dorsalis, and Culex tarsalis, but WNV was detected only in Cx. tarsalis. Average summertime temperatures and relative abundance of mosquitoes were highest in 2002 but no WNV-positive mosquitoes were detected until the following summer. In 2003, nulliparous Cx. tarsalis appeared in mid-June (first summer brood), and parous Cx. tarsalis appeared in mid-July. The first WNV-positive pool occurred 21 July, and minimum daily infections rates increased thereafter until 27 August. The minimum infection rate (MIR) for Cx. tarsalis during the season was 5.7 infected mosquitoes per 1,000 tested, with the highest infection rates occurring at the end of the season as Cx. tarsalis populations started to decline. Mid-to-late August was identified as the period of highest risk for being bitten by a WNV-infected mosquito in Grand Forks during 2003. In 2004, viral activity in Grand Forks was low, due to very cool temperatures throughout the summer. To examine the genetic diversity of the 2003 WNV isolates from Grand Forks, we sequenced a 366-nucleotide region of the capsid and premembrane gene. Thirteen (46%) of the 28 WNV isolates contained at least one nucleotide substitution when compared to the homologous region of the progenitor WN NY-99 strain, and seven of these 13 substitutions coded for amino acid changes. Thus, WNV is established in North Dakota, it appears to be evolving and it is vectored primarily by Cx. tarsalis.
West Nile virus (WNV) epizootiology was monitored from 2002 through 2005 in the area surrounding ... more West Nile virus (WNV) epizootiology was monitored from 2002 through 2005 in the area surrounding Grand Forks, North Dakota. Mosquitoes were tested for infection, and birds were surveyed for antibodies. In 2003, WNV was epidemic; in 2004, cool temperatures precluded WNV amplification; and in 2005, immunity in passerines decreased, but did not preclude, WNV amplification.
Two new species of Camallanus are described from Australian freshwater turtles. Camallanus beveri... more Two new species of Camallanus are described from Australian freshwater turtles. Camallanus beveridgei sp. nov. is reported from Elseya dentata in Northern Territory. It differs from other species of the genus parasitic in turtles by several characters including the shape of the median ridge in the buccal capsule and the position of the anterior pair of caudal papillae in males.
Uploads
Papers by Jeffrey Bell