scholarly journals Pathogenicity, Serological Responses, and Diagnosis of Experimental and Natural Malarial Infections in Native Hawaiian Thrushes

The Condor ◽  
2001 ◽  
Vol 103 (2) ◽  
pp. 209-218 ◽  
Author(s):  
Carter T. Atkinson ◽  
Julie K. Lease ◽  
Beth M. Drake ◽  
Nicholas P. Shema
Keyword(s):  
Avian Malaria ◽  
Native Hawaiian ◽  
Cell Extract ◽  
Plasma Samples ◽  
High Susceptibility ◽  
Plasmodium Relictum ◽  
True Prevalence ◽  
Hawaiian Honeycreepers ◽  
Blood Smears ◽  
Over Time

Abstract Omao (Myadestes obscurus) from the Hawaiian Islands typically have very low prevalences of infection with avian malaria (Plasmodium relictum) and it is not clear whether they share the same high susceptibility to this parasite that has been documented in native Hawaiian honeycreepers. We exposed four captive Omao to single infective mosquito bites and measured parasitemia, serological responses, and mortality over time. All four birds experienced transient infections with low parasitemias and were immune when rechallenged with multiple infective mosquito bites. By contrast, three of four honeycreepers (Maui Alauahio, Paroreomyza montana) that were exposed to the same dose and parasite isolate succumbed to infection. All four Omao developed antibodies to a common suite of malarial antigens that were detectable on immunoblots of a crude red blood cell extract of P. relictum. We used this technique to screen plasma samples from wild Omao and endangered Puaiohi (Myadestes palmeri) that were captured at elevations between 900 and 1300 m on the islands of Hawaii and Kauai. We found that the true prevalence of infection at elevations where active malaria transmission occurs is much higher than estimates based on blood smears alone. Hawaiian thrushes appear to have a high tolerance for malaria, with most individuals developing chronic, low-level infections after exposure that cannot be diagnosed accurately by blood smears.

Can lowland dry forests represent a refuge from avian malaria for native Hawaiian birds?

2010 ◽  
Vol 16 (3) ◽  
pp. 181 ◽  
Author(s):  
Katherine Tucker-Mohl ◽  
Patrick Hart ◽  
Carter T. Atkinson
Keyword(s):  
Avian Malaria ◽  
Native Hawaiian ◽  
Forest Birds ◽  
Dry Forest ◽  
Natural Resistance ◽  
Native Forest ◽  
Dry Forests ◽  
Plasmodium Relictum ◽  
Hawaiian Forest Birds ◽  
Native Birds

Hawaii?s native birds have become increasingly threatened over the past century. Introduced mosquito borne diseases such as avian malaria may be responsible for the near absence of endemic Hawaiian forest birds in low-elevation habitats. The recent recognition that some native Hawaiian forest birds may be repopulating moist lowland habitats as a result of evolved resistance to this disease has increased the conservation value of these areas. Here, we investigate whether remnant low elevation dry forests on Hawaii Island provide natural ?refuges? from mosquito-transmitted malaria by nature of their low rainfall and absence of suitable natural sources of water for mosquito breeding. Unlike lowland wet forests where high rates of disease transmission may be selecting for disease resistance, lowland dry forests may provide some refuge for native forest birds without natural resistance to malaria. We mistnetted forest birds in two lowland dry forests and tested all native birds by microscopy and serology for avian malaria caused by the Plasmodium relictum parasite. We also conducted surveys for standing water and mosquito larvae. Overall prevalence of infections with Plasmodium relictum in the Hawaii Amakihi Hemignathus virens virens was 15%. Most infected birds had lowlevel parasitemias, suggesting chronic infections. Although avian malaria is present in these lowland dry forest Amakihi populations, infection rates are significantly lower than in wet forest populations at similar elevations. Sources of breeding mosquitoes in these forests appeared to be largely anthropogenic; thus, there is potential to manage dry forests as mosquito-free habitat for Hawaii Amakihi and other Hawaiian forest birds.

Wildlife disease and conservation in Hawaii: Pathogenicity of avian malaria (Plasmodium relictum) in experimentally infected Iiwi (Vestiaria coccinea)

Parasitology ◽  
1995 ◽  
Vol 111 (S1) ◽  
pp. S59-S69 ◽  
Author(s):  
C. T. Atkinson ◽  
K. L. Woods ◽  
R. J. Dusek ◽  
L. S. Sileo ◽  
W. M. Iko
Keyword(s):  
Body Weight ◽  
Food Consumption ◽  
Native Species ◽  
Avian Malaria ◽  
Low Dose ◽  
Native Hawaiian ◽  
Forest Birds ◽  
High Dose ◽  
Plasmodium Relictum ◽  
Hawaiian Forest Birds

SUMMARYNative Hawaiian forest birds are facing a major extinction crisis with more than 75% of species recorded in historical times either extinct or endangered. Reasons for this catastrophe include habitat destruction, competition with non-native species, and introduction of predators and avian diseases. We tested susceptibility of Iiwi (Vestiaria coccinea), a declining native species, and Nutmeg Mannikins (Lonchura punctulata), a common non-native species, to an isolate ofPlasmodium relictumfrom the island of Hawaii. Food consumption, weight, and parasitaemia were monitored in juvenile Iiwi that were infected by either single (low-dose) or multiple (high-dose) mosquito bites. Mortality in both groups was significantly higher than in uninfected controls, reaching 100% of high-dose birds and 90% of low-dose birds. Significant declines in food consumption and a corresponding loss of body weight occurred in malaria-infected birds. Both sex and body weight had significant effects on survival time, with males more susceptible than females and birds with low initial weights more susceptible than those with higher initial weights. Gross and microscopic lesions in malaria fatalities included massive enlargement of the spleen and liver, hyperplasia of the reticuloendothelial system with extensive deposition of malarial pigment, and overwhelming anaemia in which over 30% of the circulating erythrocytes were parasitized. Nutmeg Mannikins, by contrast, were completely refractory to infection. Our findings support previous studies documenting high susceptibility of native Hawaiian forest birds to avian malaria. This disease continues to threaten remaining high elevation populations of endangered native birds.

The dynamics, transmission, and population impacts of avian malaria in native Hawaiian birds: a modeling approach

2011 ◽  
Vol 21 (8) ◽  
pp. 2960-2973 ◽  
Author(s):  
Michael D. Samuel ◽  
Peter H. F. Hobbelen ◽  
Francisco DeCastro ◽  
Jorge A. Ahumada ◽  
Dennis A. LaPointe ◽  
...  
Keyword(s):  
Avian Malaria ◽  
Native Hawaiian ◽  
Modeling Approach

scholarly journals PLASMODIUM RELICTUM AS A CAUSE OF AVIAN MALARIA IN WILD-CAUGHT MAGELLANIC PENGUINS (SPHENISCUS MAGELLANICUS)

1988 ◽  
Vol 24 (4) ◽  
pp. 610-619 ◽  
Author(s):  
Andrew S. Fix ◽  
Cheryl Waterhouse ◽  
Ellis C. Greiner ◽  
Michael K. Stoskopf
Keyword(s):  
Avian Malaria ◽  
Plasmodium Relictum ◽  
Spheniscus Magellanicus ◽  
Magellanic Penguins

scholarly journals Deletions of pfhrp2 and pfhrp3 genes in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda

2020 ◽  
Author(s):  
Sam L Nsobya ◽  
Andrew Walakira ◽  
Elizabeth Namirembe ◽  
Moses Kiggundu ◽  
Joaniter I Nankabirwa ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Expression ◽  
False Negative ◽  
Plasmodium Species ◽  
Pcr Amplification ◽  
Rapid Diagnostic Tests ◽  
False Negatives ◽  
Cross Sectional ◽  
True Prevalence ◽  
Blood Smears

Abstract Background: Rapid diagnostic tests (RDTs) play a key role in malaria case management. The most widely used RDT identifies Plasmodium falciparum based on immunochromatographic recognition of P. falciparum histidine-rich protein 2 (PfHRP2). Deletion of the homologous pfhrp2 and pfhrp3 genes leads to false-negative PfHRP2-based RDTs, and has been reported in P. falciparum from South America and Africa. However, identification of pfhrp2/pfhrp3 deletions has usually been based only on failure to amplify these genes using PCR, without confirmation based on protein expression, and our understanding of the true prevalence of deletions is incomplete. Methods: We investigated pfhrp2 / pfhrp3 deletions in blood samples from cross-sectional surveys in 2012-13 in three regions of varied malaria transmission intensity in Uganda. We evaluated samples with positive Giemsa-stained thick blood smears and negative PfHRP2-based RDTs by PCR amplification of conserved subunit ribosomal DNA for Plasmodium species, PCR amplification of pfhrp2 and pfhrp3 genes to identify deletions, and bead-based immunoassays for expression ofPfHRP2. Results: Of 3516 samples collected in cross-sectional surveys, 1493 (42.5%) had positive blood smears, of which 96 (6.4%) were RDT-negative. Of these 96 RDT-negative samples, P. falciparum was identified in 56 (58%) and only non-falciparum plasmodial DNA in 40 (42%). In all 56 P. falciparum -positive samples there was a failure to amplify pfhrp2 or pfhrp3 :in 25 (45%) pfhrp2 was not amplified, in 39 (70%) pfhrp3 was not amplified, and in 19 (34%) neither gene was amplified. For the 39 P. falciparum -positive, RDT-negative samples available for analysis of protein expression, PfHRP2 was not identified by immunoassay in only four samples (10.3%); these four samples all had failure to amplify both pfhrp2 and pfhrp3 by PCR. Thus, only four of 96 (4.2%) smear-positive, RDT-negative samples had P. falciparum infections with deletion of pfhrp2 and pfhrp3 confirmed by failure to amplify the genes by PCR and lack of expression of PfHRP2 demonstrated by immunoassay. Conclusion: False negative RDTs were uncommon, and deletions in pfhrp2 and pfhrp3 explained some of these findings, although most false negatives were not due to deletion of the pfhrp2 and pfhrp3 genes.

scholarly journals Avian malaria: a new lease of life for an old experimental model to study the evolutionary ecology of Plasmodium

2015 ◽  
Vol 370 (1675) ◽  
pp. 20140300 ◽  
Author(s):  
Romain Pigeault ◽  
Julien Vézilier ◽  
Stéphane Cornet ◽  
Flore Zélé ◽  
Antoine Nicot ◽  
...  
Keyword(s):  
Culex Pipiens ◽  
Avian Malaria ◽  
Evolutionary Ecology ◽  
Laboratory Research ◽  
Plasmodium Relictum ◽  
Natural Vector ◽  
The World ◽  
Experimental Laboratory ◽  
Analyse Data ◽  
Statistical Relationships

Avian malaria has historically played an important role as a model in the study of human malaria, being a stimulus for the development of medical parasitology. Avian malaria has recently come back to the research scene as a unique animal model to understand the ecology and evolution of the disease, both in the field and in the laboratory. Avian malaria is highly prevalent in birds and mosquitoes around the world and is amenable to laboratory experimentation at each stage of the parasite's life cycle. Here, we take stock of 5 years of experimental laboratory research carried out using Plasmodium relictum SGS1, the most prevalent avian malaria lineage in Europe, and its natural vector, the mosquito Culex pipiens . For this purpose, we compile and analyse data obtained in our laboratory in 14 different experiments. We provide statistical relationships between different infection-related parameters, including parasitaemia, gametocytaemia, host morbidity (anaemia) and transmission rates to mosquitoes. This analysis provides a wide-ranging picture of the within-host and between-host parameters that may bear on malaria transmission and epidemiology.

The Susceptibility of Autogenous and Anautogenous Races of Culex pipiens to Infection with Avian Malaria (Plasmodium relictum)

Parasitology ◽  
1934 ◽  
Vol 26 (4) ◽  
pp. 512-522 ◽  
Author(s):  
P. Tate ◽  
M. Vincent
Keyword(s):  
Infection Rate ◽  
Culex Pipiens ◽  
Avian Malaria ◽  
Infection Rates ◽  
Chronic Infections ◽  
Seasonal Influence ◽  
Plasmodium Relictum ◽  
The Difference ◽  
Different Strains

1. Anautogenous English and autogenous Greek, Hungarian, Maltese and cross-bred strains of C. pipiens were infected with an Algerian and a German strain of P. relictum.2. The different strains of C. pipiens behaved similarly as regards susceptibility and transmission towards the same strain of P. relictum.3. The two strains of malaria differ in the infection rate produced in mosquitoes. The Algerian strain produces an infection rate of about 89 per cent., while that of the German strain is only about 43 per cent.4. The difference in the infection rates of the two strains is not due merely to differences in the number of gametocytes formed.5. In general C. pipiens fed on birds infected with the Algerian strain of malaria became more heavily infected than those fed on birds infected with the German strain.6. C. pipiens were infected in some cases by feeding on birds with chronic infections of the Algerian strain of P. relictum, but not when fed on birds with chronic infections of the German strain.7. No seasonal influence was found as regards the infection of C. pipiens by P. relictum.8. The Algerian strain of malaria was successfully transmitted by English, Greek, Hungarian, Maltese and Greek-Hungarian strains of C. pipiens, and the German strain of malaria by English, Greek, Maltese and Greek-English strains of C. pipiens.

scholarly journals Steep declines in sightings of manta rays and devilrays (Mobulidae) in southern Mozambique

2017 ◽  
Author(s):  
Christoph A. Rohner ◽  
Anna L Flam ◽  
Simon J Pierce ◽  
Andrea D Marshall
Keyword(s):  
Environmental Variables ◽  
Linear Models ◽  
Rapid Decrease ◽  
Vulnerable Species ◽  
High Susceptibility ◽  
Generalised Linear Models ◽  
Population Growth Rates ◽  
Trend Data ◽  
Steep Decline ◽  
Over Time

Mobulid rays are one of the most vulnerable chondrichthyan groups due to their low population growth rates and high susceptibility to fisheries. While estimates of human-induced mortality are lacking, sighting trend data can provide an index of their status. We recorded underwater sightings data of Mobula alfredi, M. birostris and M. kuhlii over a 14-year period in southern Mozambique. Generalised linear models were used to standardise sightings and adjust for influences other than time. Standardised sightings of the three species, individually, declined by >90%. Declines in sightings were driven primarily by a rapid decrease between 2003–2007, although the declines continued to 2016. While environmental variables did influence sightings, they did not explain this steep decline over time. Increasing mortality from fisheries is likely to have played a significant role in the declining sightings of these vulnerable species.

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