Blood parasites of birds: a plea for more cautious terminology

Cooper, John E.; Anwar, Muhammad Sabieh

doi:10.1111/j.1474-919x.2001.tb04180.x

Cited by 16 publications

(4 citation statements)

References 5 publications

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“…Microscopic examination of blood smears by Steadman et al (1990) (used for PCR in this study) revealed no parasites in introduced or indigenous birds on the Cook Islands. This could be due to low-intensity peripheral parasitemia and is consistent with some previous studies comparing PCR and blood smears (Cooper & Anwar 2001;Jarvi et al 2002;Richard et al 2002). The Jarvi et al (2002) study is particularly relevant, as these authors found a haematozoan prevalence of 59% of 188 birds of eight species in Samoa versus and 0% from 214 smears evaluated.…”

Section: Discussion (A) Prevalence Of Parasitessupporting

confidence: 89%

Prevalence and evolutionary relationships of haematozoan parasites in native versus introduced populations of common mynaAcridotheres tristis

et al. 2005

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The success of introduced species is frequently explained by their escape from natural enemies in the introduced region. We tested the enemy release hypothesis with respect to two well studied blood parasite genera (Plasmodium and Haemoproteus) in native and six introduced populations of the common myna Acridotheres tristis. Not all comparisons of introduced populations to the native population were consistent with expectations of the enemy release hypothesis. Native populations show greater overall parasite prevalence than introduced populations, but the lower prevalence in introduced populations is driven by low prevalence in two populations on oceanic islands (Fiji and Hawaii). When these are excluded, prevalence does not differ significantly. We found a similar number of parasite lineages in native populations compared to all introduced populations. Although there is some evidence that common mynas may have carried parasite lineages from native to introduced locations, and also that introduced populations may have become infected with novel parasite lineages, it may be difficult to differentiate between parasites that are native and introduced, because malarial parasite lineages often do not show regional or host specificity.

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Section: Discussion (A) Prevalence Of Parasitessupporting

confidence: 89%

Prevalence and evolutionary relationships of haematozoan parasites in native versus introduced populations of common mynaAcridotheres tristis

et al. 2005

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“…A 200· lens was used to look for extracellular parasites in one half of each smear. Intracellular stages of haematoza were sought at 400· but, in contrast to the usual method (see, for instance, Merino and Potti 1995), we scanned the whole smear following the recommendations of Cooper and Anwar (2001). The oil immersion objective was used when a possible parasite was located at 400·.…”

Section: Methodsmentioning

confidence: 99%

Parasite Pressure and its Effects on Blood Parameters in a Stable and Dense Population of the Endangered Lesser Grey Shrike

2005

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The risk that pathogens and parasites pose to endangered species is increasingly evident. Nonetheless, this is frequently overlooked when considering causes of decline of species and conservation practices. Here, we study the ecto and haemoparasites of adult and nestling Lesser grey shrikes Lanius minor from a dense and stable breeding population in central Europe and their effect on host blood parameters. We found three species of haemoparasites (Haemoproteus sp., microfilariae tentatively assigned to the family Splendidofilariae and Trypanosoma sp.) and two ectoparasite taxa (Menacanthus camelinus and feather mites -Acarina-). Our data suggest that the studied population, located in an area with traditional and extensive farming, is not under a strong parasite pressure. Despite this, indirect measures of immunocompetence (haematocrit and sedimentation rate) showed an association between haemoparasites and health status: while haematocrit did not differ between parasitised and non-parasitised individuals, adult shrikes with haematozoa had significantly lower sedimentation rates than did non-parasitised birds.

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“…For this study, we used the presence or absence of any blood parasite found in blood smears as an indicator of an acute infection with blood parasites. Since we were not interested in birds with very low parasitaemia, we worked under the assumption that blood smears screened for a fixed time (30 min in the present study) are an appropriate tool by which to detect acute infections, although we must accept the fact that infections detectable at only certain times of day may have been missed (see Cooper and Anwar 2001).…”

Section: Passerinesmentioning

confidence: 99%

Effect of endurance flight on haematocrit in migrating birds

et al. 2006

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The effects of an endurance flight on the haematocrit, the percentage of packed red blood cells per blood volume, were examined within the framework of six possible factors explaining possible changes in the haematocrit. Two approaches were adopted: (1) the haematocrit was studied in four species of passerine birds which landed on an Italian island after having crossed the Mediterranean Sea on their spring migration in a non-stop flight; (2) the haematocrit was evaluated in six individual red knots after a flight of 1, 2, 4 and 10 h in a wind tunnel and the data thus obtained compared with data on resting birds with or without food. In the four passerine species, the haematocrit decreased from 51% in fat birds to 48% in lean birds. In lean birds, the haematocrit dropped from 48% in birds with well-developed breast muscles to 36% in birds with emaciated breast muscles. In the red knots, the haematocrit was dependent on body mass in flying and resting birds. The haematocrit decreased from about 51% pre-flight to about 49% within 1 h of flight and remained at this level for up to 10 h of flight. Taking the results from the passerines and the red knots together, it seems that the haematocrit drops by a few percentage points within 1 h after the onset of flight, decreases very slowly with decreasing body mass and decreases more steeply in very lean birds having entered stage III of fasting. This indicates that dehydration is not an underlying factor in decreased haematocrit because if this were the case we would expect an increase with endurance flight. We found no effect of the presence of blood parasites on haematocrit. With the onset of flight, haemodilution may be adaptive, because it reduces blood viscosity and, thereby, energy expenditure by the heart, or it may be a sign of water conservation as an insurance against the risk of dehydration during long non-stop flights. During endurance flight, a reduction in the haematocrit may be adaptive, in that oxygen delivery capacity is adjusted to the decreased oxygen needs as body mass decreases. A decreasing haematocrit would also allow birds to reduce heart beat frequency and/or heart size, because blood viscosity decreases disproportionally with decreasing haematocrit. However, when energy stores are about to come to an end and birds increase protein breakdown, the haematocrit decreases even further, and birds probably become anaemic due to a reduced erythropoiesis.

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Blood parasites of birds: a plea for more cautious terminology

Cited by 16 publications

References 5 publications

Prevalence and evolutionary relationships of haematozoan parasites in native versus introduced populations of common mynaAcridotheres tristis

Prevalence and evolutionary relationships of haematozoan parasites in native versus introduced populations of common mynaAcridotheres tristis

Parasite Pressure and its Effects on Blood Parameters in a Stable and Dense Population of the Endangered Lesser Grey Shrike

Effect of endurance flight on haematocrit in migrating birds

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