Prevalence Of Blood Parasites Research Articles

Blood parasites in Brazilian Atlantic Forest birds: effects of fragment size and habitat dependency

SummaryDeforestation, fragmentation and habitat disturbance may alter the relationship between pathogens and hosts. We tested, apparently for the first time, whether habitat fragmentation and degree of dependence on forests affect the prevalence of avian blood parasites. We estimated the prevalence of Plasmodium, Haemoproteus and Trypanosoma through the inspection of 925 blood smears from 109 species captured in six pairs of small (< 30 ha) and large (> 1,000 ha) Brazilian Atlantic Forest fragments. Prevalence of the three types of parasites did not differ between small and large forest patches. Forest-independent birds were usually more infected with Plasmodium and Haemoproteus than other birds, but forest-dependent birds were more infected with Trypanosoma. Parasite richness on birds was not affected by patch size.

Ant‐following and the prevalence of blood parasites in birds of African rainforests

Blood parasites are widespread in birds, several are pathogenic and may affect the fitness of their hosts, and their evolution. By reanalyzing recently published data I show that parts of the variation in prevalences of parasites in the blood of African rainforest birds and the occurrence of similar or same parasite haplotypes in rather unrelated birds are well understood when considering the ecological aspects of foraging of some of these birds. Specialized ant‐following birds, which regularly follow the massive swarm raids of army ants and feed on insects flushed by the ants, have higher prevalences of nematode microfilariae (~10×),Trypanosoma(~10×), andPlasmodiumparasites (~2×) and a much higher probability of infection with multiple parasites than other birds. Moreover, birds regularly attending army ant swarms share identicalTrypanosomahaplotypes and show genetically similar microfilariae haplotypes. I conclude that ant‐following increases the probability of birds to get infected with blood parasites and may facilitate the switch of a parasite species from one host species to another. The costs of higher parasite intensities involved when specializing on following ant swarms may have influenced the evolution of foraging behaviour in birds of African rainforests and may help to explain the relatively low number of specialized ant‐following bird species on the African continent.

Erratum to: Reduced blood parasite prevalence with age in the Seychelles Warbler: selective mortality or suppression of infection?

Erratum to: J Ornithol DOI 10.1007/s10336-009-0427-x Additional affiliation to one of the authors is given here: D. S. Richardson 5 Nature Seychelles, P.O. Box 1310, Victoria, Mahé, Republic of Seychelles

BLOOD PARASITES IN BIRDS FROM MADAGASCAR

Madagascar has long been recognized for its unique and diverse biota. In particular, significant effort has been made to establish baseline population data to better conserve the endemic avifauna. During field expeditions between 1993 and 2004, birds were mist-netted at 11 different sites, at elevations from 60 m to 2,050 m above sea level. Data on endemic status, forest type, and habitat preference were recorded. Thin blood films from 947 birds, belonging to 26 families and 64 species, were examined by light microscopy to determine the prevalence of blood parasites. Of these 947 birds, 30.7% were infected by at least one species of blood parasite, 26.8% of which were infected by more than one species. Species of Haemoproteus were the most prevalent (17.4%), followed by microfilariae (11.0%), Leucocytozoon spp. (9.4%), Plasmodium spp. (1.9%), Trypanosoma spp. (0.9%), and Babesia spp. (0.2%). Species level identifications confirmed the presence of 47 species of hemosporidians and trypanosomes, which is notably high and mirrors the diversity of their avian hosts. Eleven (23.4%) of these parasite species were new to science and thought to be endemic to the island. Significant differences in prevalence were observed by sample site, forest type (humid vs. dry), and habitat preference. Birds from all elevational zones sampled were infected, although not all parasite genera were present in each zone. Four of the six endemic avian families or subfamilies (Bernieridae, Brachypteraciidae, Philepittinae [Eurylaimidae], and Vangidae) were sampled and found to be parasitized. Of the families with the largest sample sizes, the Zosteropidae and Ploceidae had the highest prevalence of infection (65.6% and 49.3%, respectively). The vectors of hematozoan parasites in Madagascar are currently unknown. These results add to the current knowledge of avian parasitism in Madagascar and are of particular interest for the conservation of endemic species, as well as threatened or endangered populations.

Prevalence and diversity patterns of avian blood parasites in degraded African rainforest habitats

Land use changes including deforestation, road construction and agricultural encroachments have been linked to the increased prevalence of several infectious diseases. In order to better understand how deforestation affects the prevalence of vector-borne infectious diseases in wildlife, nine paired sites were sampled (disturbed vs. undisturbed habitats) in Southern Cameroon. We studied the diversity, prevalence and distribution of avian malaria parasites (Plasmodium spp.) and other related haemosporidians (species of Haemoproteus and Leucocytozoon) from these sites in two widespread species of African rainforest birds, the yellow-whiskered greenbul (Andropadus latirostris, Pycnonotidae) and the olive sunbird (Cyanomitra olivacea, Nectariniidae). Twenty-six mitochondrial cytochrome b lineages were identified: 20 Plasmodium lineages and 6 Haemoproteus lineages. These lineages showed no geographic specificity, nor significant differences in lineage diversity between habitat types. However, we found that the prevalence of Leucocytozoon and Haemoproteus infections were significantly higher in undisturbed than in deforested habitats (Leucocytozoon spp. 50.3% vs. 35.8%, Haemoproteus spp. 16.3% vs. 10.8%). We also found higher prevalence for all haemosporidian parasites in C. olivacea than in A. latirostris species (70.2% vs. 58.2%). Interestingly, we found one morphospecies of Plasmodium in C. olivacea, as represented by a clade of related lineages, showed increased prevalence at disturbed sites, while another showed a decrease, testifying to different patterns of transmission, even among closely related lineages of avian malaria, in relation to deforestation. Our work demonstrates that anthropogenic habitat change can affect host-parasite systems and result in opposing trends in prevalence of haemosporidian parasites in wild bird populations.

Reduced blood parasite prevalence with age in the Seychelles Warbler: selective mortality or suppression of infection?

Avian malaria can affect survival and reproduction of their hosts. Two patterns commonly observed in birds are that females have a higher prevalence of malaria than do males and that prevalence decreases with age. The mechanisms behind these patterns remain unclear. However, most studies on blood parasite infections are based on cross-sectional analyses of prevalence, ignoring malaria related mortality and individual changes in infection. Here, we analyse both within-individual changes in malaria prevalence and long-term survival consequences of infection in the Seychelles Warbler (Acrocephalus sechellensis). Adults were less likely to be infected than juveniles but, contrary to broad patterns previously reported in birds, females were less likely to be infected than males. We show by screening individual birds in two subsequent years that the decline with age is a result both of individual suppression of infection and selective mortality. Birds that were infected early in life had a lower survival rate compared to uninfected birds, but among those that survived to be screened twice the proportion of infected birds had also decreased. Uninfected birds did not become infected later in life. Males were found to be more infected than females in this species possibly because, unlike most birds, males are the dispersing sex and the cost of dispersal may have to be traded against immunity. Infected males took longer to suppress their infection than did females. We conclude that these infections are indeed costly, and that age-related patterns in blood parasite prevalence are influenced both by suppression and selective mortality.

Reduced parasite infestation in urban Eurasian blackbirds (Turdus merula): a factor favoring urbanization?

Humans nowadays dramatically alter environmental and ecological conditions worldwide. One of the most extreme forms of anthropogenic land-use alteration is urbanization. Animals thriving in urban areas are not only exposed to different environmental conditions compared with their nonurban conspecifics, but prevalence and impacts of wildlife diseases on urban populations may also be affected. In the present study, we tested whether blood-parasite prevalence differs between urban and forest habitats by comparing haematozoan infections of urban and forest-living Eurasian blackbirds ( Turdus merula L., 1758). In total, 76% of Eurasian blackbirds were infected with haematozoa and we detected five different blood parasite genera in both habitats. Blood-parasite prevalence varied both between years and between spring and summer in both urban and forest populations. Forest blackbirds had more parasite genera per individual than urban blackbirds, and in summer, forest blackbirds had higher blood-parasite prevalence than their urban conspecifics. These differences in blood-parasite prevalence between urban and forest blackbirds suggest a lower risk of haematozoan infections in urban than in forest habitats. The lower parasite prevalence could be one of the factors favoring the invasion of urban ecosystems.

Fitness in common buzzards at the cross‐point of opposite melanin–parasite interactions

1 Melanin is one of the major pigments of vertebrates and has many suggested functions. Although it is supposed to have an antipathogenic effect, its relationship to infection with ecto- and endoparasites largely remains to be examined. 2 The common buzzard Buteo buteo occurs in three eumelanin morphs which differ in their lifetime reproductive success. We examined the distribution of the blood-sucking ectoparasite Carnus haemapterus and the blood parasite Leucocytozoon toddi among buzzard nestlings and related parasite infection to the morph of the host and its parents. We controlled the effect of melanin morph on parasites for the potentially confounding total leukocyte numbers, heterophil : lymphocyte ratio (H : L ratio), age, sex, hierarchical rank within the brood and annual food availability. 3 Blood parasite prevalence was lower in offspring of intermediately coloured males. This pattern was apparent during high and low food availability, and although this result did not remain under intermediate vole densities, it could contribute to observed fitness differences in male buzzards. In contrast, carnid fly score increased with darkness of the host plumage. However, among chicks infected with the blood parasite, Leucocytozoon infection intensity decreased with plumage darkness. 4 The two parasite species may exert selection pressures in opposite directions on melanism of their host. Therefore, buzzards with intermediate amounts of melanin may prosper as they are sufficiently protected against endoparasites, but not too attractive for ectoparasites. Parasites could help explain the persistence of colour polymorphism in their buzzard host.

Isotope signatures in winter moulted feathers predict malaria prevalence in a breeding avian host

It is widely accepted that animal distribution and migration strategy might have co-evolved in relation to selection pressures exerted by parasites. Here, we first determined the prevalence and types of malaria blood parasites in a breeding population of great reed warblers Acrocephalus arundinaceus using PCR. Secondly, we tested for differences in individual feather stable isotope signatures (delta (13)C, delta (15)N, deltaD and delta (34)S) to investigate whether malaria infected and non-infected birds had occupied different areas in winter. We show that birds moulting in Afro-tropical habitats with significantly higher delta (13)C and delta (15)N but lower deltaD and delta(34)S values were more frequently infected with malaria parasites. Based on established patterns of isotopic distributions, our results indicate that moulting sites with higher incidence of malaria are generally drier and situated further to the north in West Africa than sites with lower incidence of malaria. Our findings are pertinent to the general hypothesis that animal distribution and particularly avian migration strategy might evolve in response to selection pressures exerted by parasites at different geographic scales. Tradeoffs between investment in energy demanding life history traits (e.g. migration and winter moult) and immune function are suggested to contribute to the particular choice of habitat during migration and at wintering sites.

Prevalence of Hematozoa in Falcons in the United Arab Emirates With Respect to the Origin of Falcon Hosts

To determine the prevalence of blood parasites with regard to country of origin in a population of falcons kept in the United Arab Emirates (UAE), 432 falcons of 3 different species and 2 hybrid species originating from Asia, Europe, and the United States were examined. Birds were divided into 2 groups. Group 1 comprised 323 birds examined immediately after arrival in the UAE. Blood parasites were detected in 6.8% of birds. Group 2 comprised 109 birds kept longer than 5 months in the UAE; of these, 15.6% were positive for blood parasites. No hybrids (captive bred birds from the United States or Germany) were positive in group 1, whereas 18.2% of the gyrfalcon/saker and 5.9% of the gyrfalcon/peregrine hybrids in group 2 were infected with blood parasites. Wild-caught birds from Asia were positive in both groups. In total, 39 (9%) of the 432 falcons examined were infected with blood parasites. The blood parasites detected were identified as Haemoproteus tinnunculi (5.3%), Haemoproteus brachiatus (0.9%), Leucocytozoon toddi (0.9%), and rickettsia-like parasites (1.9%). This study appears to be the first to investigate the prevalence of blood parasites within the UAE with regard to the origin of the birds. Additionally, it is the first report of H brachiatus in a saker falcon (Falco cherrug). No correlations were found between infection with a blood parasite and clinical disease in the birds in this study.

Habitat Effects on Physiological Stress Response in Nestling Blue Tits Are Mediated through Parasitism

Abstract We investigated determinants of the physiological stress response mediated by stress proteins in blue tit Cyanistes caeruleus nestlings growing up in oak forests in central Spain, resulting from different forest management practices. We assessed circulating levels of the heat-shock protein HSP60 as an integrated physiological measure of the conditions experienced by nestlings during postnatal development. The effects of habitat quality and parasite infections on nestling rearing environment were then assessed through this measurement of stress response. Our results showed that newly acquired ecto- and hemoparasite infections were associated with forest habitat structural characteristics, higher prevalence of fleas and blood parasites in more mature forests, and higher prevalence of blowflies in degraded forests. While habitat characteristics did not explain variation in stress protein levels, infestation by blowfly larvae of the genus Protocalliphora and hematozoa infection by Leucocytozoon were significantly associated with higher levels of HSP60. Thus, upregulation of the expression of certain stress proteins seems to be a common physiological mechanism to alleviate the negative impact of parasite infections in growing birds. Habitat characteristics may thus indirectly determine growth conditions for forest birds mediated through their association with one of the most important selection pressures for offspring development, parasite infections.

Prevalence and Intensity of Blood Parasites in Wild Pigeons and Doves (Family: Columbidae) from Shasha Forest Reserve, Ile-Ife, Nigeria

Prevalence and Intensity of Blood Parasites in Wild Pigeons and Doves (Family: Columbidae) from Shasha Forest Reserve, Ile-Ife, Nigeria

Flight distance and blood parasites in birds

Flight distance reflects the risk that an individual animal is willing to take when approached by a potential predator. Because residual reproductive value is the average number of offspring that an individual of a given age class is expected to produce after the current reproductive event, individuals with low residual reproductive value should take greater risks than the average individual to make them more likely to gain at least some reproductive success. Therefore, I predicted that individuals belonging to bird species with intense infections with virulent parasites to take greater risks than individuals of species with few or no virulent parasites. In a comparative study of mean flight distance of 133 different bird species, as estimated from the distance at which individuals fled when approached by a human, relative flight distance decreased with the number of blood parasite species and the prevalence of blood parasites, as expected if parasitism reduces residual reproductive value. Birds that take great risks in terms of reduced flight distance run elevated risks of mortality by predators that are allowed to approach potential prey. However, relative flight distance decreased independently for species richness and prevalence of blood parasites and for risk of predation due to the European sparrow hawk Accipiter nisus. These findings suggest that standardized measures of flight distance provide reliable information about risk taking by individuals, with important consequences for life history, parasitism, and risk of predation.

In superb fairy wrens (Malurus cyaneus), nuptial males have more blood parasites and higher haemoglobin concentration than eclipsed males

Blood parasites rupture mature red blood cells and so reduce haemoglobin concentration and hence the potential activity levels of infected males. We examined blood parasites and haemoglobin concentration in the superb fairy-wren (Malurus cyaneus) across three years and six locations in South Australia. We tested the prediction that males in nuptial plumage have more blood parasites and hence lower haemoglobin concentration than males in eclipsed plumage. Of 188 birds, 20 (10.6%) had blood parasites (Haemaproteus spp). We found that (1) there was an effect of season and sex on haemoglobin concentration; (2) there was no effect of haemoglobin concentration on prevalence of blood parasites or intensity; and (3) males in nuptial plumage had more blood parasites but higher haemoglobin concentration than eclipsed males.

English

A four-year study to determine the prevalence of both blood and gastro-intestinal parasites of man was done in all the eighteen local government areas of Edo State, Nigeria. The study, which commenced in January of 2000, ended in December of 2004. Of the 136,360 samples examined, 1000 that is 0.7% had parasites. A total of eleven parasites species were identified. A seasonal pattern of parasitic infection was noted with a high prevalence in the rainy (wet) season months of April to November and a low prevalence in the dry season months of December to March. The prevalence was significantly higher in September, October and November at 22, 10 and 10% respectively (P<0.05); than other months of the year. February had the least prevalence of 10%. The local government areas in the rain-forest zone, south of the state had significantly higher prevalence than the local government areas in the grassland, north of the state (P<0.05). Of the eleven parasite species observed in the study, Ascaris lumbricoides and Plasmodium falciparum had the highest prevalence of 30 and 35%, respectively. Hookworm parasites, Trichuris triciura and Strongyloides stercoralishad the prevalence of 10, 7 and 1%, respectively. The protozoans, Entamoeba coli,Entamoeba histolytica, and Giardia lamblia had prevalence of 6, 4 and 3% respectively. Schistosoma haematobium, Loa loa and Enterobius vermicularis had the least prevalence of 2, 1 and 1%, respectively. With the exception of S. haematobium, E.  vermicularis, and L. loa, which occurred in few local government areas, the other eight parasite species were encountered in all the local government areas. There was a higher prevalence of parasitic infections in this study than in the hospital records in the state.   Key words: Blood, gastro-intestinal, parasites, and infection in Edo state.

Immunological change in a parasite-impoverished environment: divergent signals from four island taxa.

Dramatic declines of native Hawaiian avifauna due to the human-mediated emergence of avian malaria and pox prompted an examination of whether island taxa share a common altered immunological signature, potentially driven by reduced genetic diversity and reduced exposure to parasites. We tested this hypothesis by characterizing parasite prevalence, genetic diversity and three measures of immune response in two recently-introduced species (Neochmia temporalis and Zosterops lateralis) and two island endemics (Acrocephalus aequinoctialis and A. rimitarae) and then comparing the results to those observed in closely-related mainland counterparts. The prevalence of blood parasites was significantly lower in 3 of 4 island taxa, due in part to the absence of certain parasite lineages represented in mainland populations. Indices of genetic diversity were unchanged in the island population of N. temporalis; however, allelic richness was significantly lower in the island population of Z. lateralis while both allelic richness and heterozygosity were significantly reduced in the two island-endemic species examined. Although parasite prevalence and genetic diversity generally conformed to expectations for an island system, we did not find evidence for a pattern of uniformly altered immune responses in island taxa, even amongst endemic taxa with the longest residence times. The island population of Z. lateralis exhibited a significantly reduced inflammatory cell-mediated response while levels of natural antibodies remained unchanged for this and the other recently introduced island taxon. In contrast, the island endemic A. rimitarae exhibited a significantly increased inflammatory response as well as higher levels of natural antibodies and complement. These measures were unchanged or lower in A. aequinoctialis. We suggest that small differences in the pathogenic landscape and the stochastic history of mutation and genetic drift are likely to be important in shaping the unique immunological profiles of small isolated populations. Consequently, predicting the impact of introduced disease on the many other endemic faunas of the remote Pacific will remain a challenge.

Ecological factors influencing disease risk in Eagle OwlsBubo bubo

In this study we assessed whether local habitat features and host population density influenced disease risk in Eagle OwlBubo bubofledglings. Measures of immune defence (concentrations of circulating white blood cells), prevalence of three parasite types (a blood parasiteLeucocytozoon ziemanni, an insectCarnus haemapterus, and a tickRhipicephalussp.) and total number of parasite species were used to quantify disease risk. We tested the hypotheses that disease risk in fledglings was higher in nests located in areas with higher length of and proximity to watercourses (as a higher abundance and viability of parasites and vectors occur in wetter areas), higher cover of forest (as forest moistness and humidity can favour higher vector and parasite proliferation), higher habitat diversity (as environmental heterogeneity increases the pool of potential vectors and parasites) and higher local owl population density (as disease transmission might be density‐dependent). The clearest relationship was with the proximity of freshwater, although the other hypotheses were also partially supported. Concentrations of white blood cells, the number of parasite species and, weakly, the prevalence ofCarnus haemapteruswere all higher in nests closer to watercourses. The prevalence of blood parasites increased with the cover of forested areas. Fledglings from nests located in more diverse habitats had higher white blood cell concentrations and showed higher prevalence of blood parasites. Finally, local host population density was positively correlated with the prevalence of blood parasites. The results suggest the existence of complex and interrelated links between ecological parameters and three different measures of disease risk, and highlight the importance of immunological approaches to assess disease risk at an intraspecific level.

MALARIA AND RISK OF PREDATION: A COMPARATIVE STUDY OF BIRDS

Predators have been hypothesized to prey on individuals in a poor state of health, although this hypothesis has only rarely been examined. We used extensive data on prey abundance and availability from two long-term studies of the European Sparrowhawk (Accipiter nisus) and the Eurasian Goshawk (Accipiter gentilis) to quantify the relationship between predation risk of different prey species and infection with malaria and other protozoan blood parasites. Using a total of 31 745 prey individuals of 65 species of birds from 1709 nests during 1977-1997 for the Sparrowhawk and a total of 21 818 prey individuals of 76 species of birds from 1480 nests for the Goshawk during 1977-2004, we show that prey species with a high prevalence of blood parasites had higher risks of predation than species with a low prevalence. That was also the case when a number of confounding variables of prey species, such as body mass, breeding sociality, sexual dichromatism, and similarity among species in risk of predation due to common descent, were controlled in comparative analyses of standardized linear contrasts. Prevalence of the genera Haemoproteus, Leucocytozoon, Plasmodium, and Trypanosoma were correlated with each other, and we partitioned out the independent effects of different protozoan genera on predation risk in comparative analyses. Prevalence of Haemoproteus, Leucocytozoon, and Plasmodium accounted for interspecific variation in predation risk for the two raptors. These findings suggest that predation is an important factor affecting parasite-host dynamics because predators tend to prey on hosts that are more likely to be infected, thereby reducing the transmission success of parasites. Furthermore, this study demonstrates that protozoan infections are a common cause of death for hosts mediated by increased risk of predation.

Feeding innovations and parasitism in birds

The rate of behavioural innovation, such as opportunistic feeding innovation, may facilitate adaptation to novel environments. Because parasites may affect how their hosts adopt novel means of resource acquisition, or because opportunistic behaviours may involve the risk of being exposed to a large parasite fauna, we hypothesize an evolutionary link between the rate of feeding innovations and parasitism. We investigated the phylogenetic relationship between relative frequency of feeding innovations (adjusted for research effort and population size) and relative size of immune defense organs (as a relative measure of parasite-mediated selection) and the prevalence of blood parasites in birds. Using generalized least squares models, we found that species with relatively large bursa of Fabricius, thymus, and spleen had higher rates of feeding innovations than species with small immune defense organs. Similarly, there was a positive interspecific association between feeding innovation and haematozoa prevalence. These relationships were not confounded by migration, relative brain size, geographical distribution, and male plumage brightness. Analyses of causality relying on evolutionary modelling of discrete variables and path analysis suggest that increasing rate of feeding innovation may place species under intense selection due to parasitism. Therefore, behavioural adaptation by feeding innovation seems to have consequences for the coevolutionary arm race between parasites and hosts. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90, 441–455.

Blood Parasites in Birds From the Lowlands of Northern Colombia

Blood samples from 302 wild and domesticated birds (75 species, 24 families) from two zones of lowlands in northern Colombia (Urabá Gulf and Lower Cauca) were examined for haematozoa. Microscopic observation of blood smears stained with Giemsa revealed twenty-eight individuals of 16 species (9.3% of all birds) infected with parasites of at least one genus. Plasmodium spp. accounted for 5.6% of the infections, followed by Haemoproteus spp. (2.6%), Leucocytozoon spp. (0.3%) and unidentified microfilariae (1.0%). This survey reports four species examined for the first time and four new records of hosts of haematozoa. In agreement with previous studies in the Neotropics, the prevalence of blood parasites was low in comparison to other regions of the world.