Recent Advances in Studies on Avian Malaria Parasites

Marzal, Alfonso

doi:10.5772/33730

Cited by 43 publications

(40 citation statements)

References 102 publications

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“…Exo-erythrocytic development of several Haemamoeba and Giovannolaia malaria parasites were subjects of experimental research in many laboratories in America and Europe (Table 1). However, after the discovery of malaria parasites in rodents and monkeys, which are closer to malaria parasites of humans in many biological and genetic characteristics and also are more convenient model organisms for the laboratory experimental research, the interest of human malariologists in avian malaria parasites gradually decreased in the 1960s [3, 4, 9, 53]. Because of the difficulties in designing experiments with parasites of wild birds and the unidentified vectors of many Plasmodium species, the exo-erythrocytic development of the great majority of avian malaria parasites of subgenera Giovannolaia, Novyella and Huffia remains unknown or only fragmentary information about their secondary exo-erythrocytic merogony is available (Table 1).…”

Section: Resultsmentioning

confidence: 99%

Exo-erythrocytic development of avian malaria and related haemosporidian parasites

Valkiūnas

Iezhova

2017

Malar J

108

159

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Background: Avian malaria parasites (Plasmodium spp.) and related haemosporidians (Haemosporida) are responsible for diseases which can be severe and even lethal in avian hosts. These parasites cause not only blood pathology, but also damage various organs due to extensive exo-erythrocytic development all over the body, which is not the case during Plasmodium infections in mammals. However, exo-erythrocytic development (tissue merogony or schizogony) remains the most poorly investigated part of life cycle in all groups of wildlife haemosporidian parasites. In spite of remarkable progress in studies of genetic diversity, ecology and evolutionary biology of avian haemosporidians during the past 20 years, there is not much progress in understanding patterns of exo-erythrocytic development in these parasites. The purpose of this review is to overview the main information on exo-erythrocytic development of avian Plasmodium species and related haemosporidian parasites as a baseline for assisting academic and veterinary medicine researchers in morphological identification of these parasites using tissue stages, and to define future research priorities in this field of avian malariology. Methods:The data were considered from peer-reviewed articles and histological material that was accessed in zoological collections in museums of Australia, Europe and the USA. Articles describing tissue stages of avian haemosporidians were included from 1908 to the present. Histological preparations of various organs infected with the exo-erythrocytic stages of different haemosporidian parasites were examined. Results:In all, 229 published articles were included in this review. Exo-erythrocytic stages of avian Plasmodium, Fallisia, Haemoproteus, Leucocytozoon, and Akiba species were analysed, compared and illustrated. Morphological characters of tissue stages that can be used for diagnostic purposes were specified. Conclusion:Recent molecular studies combined with histological research show that avian haemosporidians are more virulent than formerly believed. The exo-erythrocytic stages can cause severe disease, especially in non-adapted avian hosts, suggesting the existence of a group of underestimated malignant infections. The development of a given haemosporidian strain can be markedly different in different avian hosts, resulting in significantly different virulence. A methodology combining the traditional histology techniques with molecular diagnostic tools is essential to speed research in this field of avian malariology.

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Section: Resultsmentioning

confidence: 99%

Exo-erythrocytic development of avian malaria and related haemosporidian parasites

Valkiūnas

Iezhova

2017

Malar J

108

159

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“…Birds are an ideal study system as avian haematozoans are common and co‐infections are abundant (Sehgal, Jones & Smith ; Atkinson, Thomas & Hunter ; Marzal et al . ; Marzal ; Oakgrove et al . ; van Rooyen et al .…”

Section: Introductionmentioning

confidence: 99%

Co‐infections and environmental conditions drive the distributions of blood parasites in wild birds

Clark

Wells

Dimitrov

et al. 2016

Journal of Animal Ecology

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Summary 1.Experimental work increasingly suggests that non-random pathogen associations can affect the spread or severity of disease. Yet due to difficulties distinguishing and interpreting co-infections, evidence for the presence and directionality of pathogen co-occurrences in wildlife is rudimentary. 2. We provide empirical evidence for pathogen co-occurrences by analysing infection matrices for avian malaria (Haemoproteus and Plasmodium spp.) and parasitic filarial nematodes (microfilariae) in wild birds (New Caledonian Zosterops spp.). 3. Using visual and genus-specific molecular parasite screening, we identified high levels of co-infections that would have been missed using PCR alone. Avian malaria lineages were assigned to species level using morphological descriptions. We estimated parasite co-occurrence probabilities, while accounting for environmental predictors, in a hierarchical multivariate logistic regression. 4. Co-infections occurred in 36% of infected birds. We identified both positively and negatively correlated parasite co-occurrence probabilities when accounting for host, habitat and island effects. Two of three pairwise avian malaria co-occurrences were strongly negative, despite each malaria parasite occurring across all islands and habitats. Birds with microfilariae had elevated heterophil to lymphocyte ratios and were all co-infected with avian malaria, consistent with evidence that host immune modulation by parasitic nematodes facilitates malaria co-infections. Importantly, co-occurrence patterns with microfilariae varied in direction among avian malaria species; two malaria parasites correlated positively but a third correlated negatively with microfilariae. 5. We show that wildlife co-infections are frequent, possibly affecting infection rates through competition or facilitation. We argue that combining multiple diagnostic screening methods with multivariate logistic regression offers a platform to disentangle impacts of environmental factors and parasite co-occurrences on wildlife disease.

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“…Concerns have been raised regarding the ethical issues and the viability of using primates as biomedical research models [Pound et al, 2004;Bailey, 2005;Knight, 2008]. However, studies of avian malarial parasites, using birds and less invasive testing methods, have shown promise in research on malarial vaccines [Marzal, 2012].…”

Section: Discussionmentioning

confidence: 99%

Disappearing in the Night: An Overview on Trade and Legislation of Night Monkeys in South and Central America

Svensson

Shanee²,

Shanee³

et al. 2017

IJFP

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The international trade in night monkeys (Aotus spp.), found throughout Central and South America, has been regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) since 1975. We present a quantitative analysis of this trade from all 9 range countries, over 4 decades, and compare domestic legislation to CITES regulations. Night monkeys were exported from 8 of the 9 habitat countries, totalling 5,968 live individuals and 7,098 specimens, with trade of live individuals declining over time. In terms of species, the most commonly traded was Aotus nancymaae (present in Brazil, Colombia, Peru) followed by A. vociferans (Brazil, Colombia, Ecuador, Peru) and A. zonalis (Colombia, Panama). There was no significant correlation between levels of trade and species' geographic range size or the number of countries in which a species occurs. Five countries have legislation that meets CITES requirements for implementation, whereas the other 4 countries' legislation showed deficiencies. Research conducted in Colombia, Peru, and Brazil suggests significant cross-border trade not captured in official international trade registers. Although international trade has diminished, current trends suggest that populations of rarer species may be under unsustainable pressure. Further research is needed to quantify real trade numbers occurring between habitat countries.

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Recent Advances in Studies on Avian Malaria Parasites

Cited by 43 publications

References 102 publications

Exo-erythrocytic development of avian malaria and related haemosporidian parasites

Exo-erythrocytic development of avian malaria and related haemosporidian parasites

Co‐infections and environmental conditions drive the distributions of blood parasites in wild birds

Disappearing in the Night: An Overview on Trade and Legislation of Night Monkeys in South and Central America

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