Persistent low avian malaria in a tropical species despite high community prevalence.
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ABSTRACT:
SUBMITTER: Eastwood JR
PROVIDER: S-EPMC6350384 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The malaria parasites (Apicomplexa: Haemosporida) of birds are believed to have diversified across the avian host phylogeny well after the origin of most major host lineages. Although many symbionts with direct transmission codiversify with their hosts, mechanisms of species formation in vector-borne parasites, including the role of host shifting, are poorly understood. Here, we examine the hosts of sister lineages in a phylogeny of 181 putative species of malaria parasites of New World terrestrial birds to determine the role of shifts between host taxa in the formation of new parasite species. We find that host shifting, often across host genera and families, is the rule. Sympatric speciation by host shifting would require local reproductive isolation as a prerequisite to divergent selection, but this mechanism is not supported by the generalized host-biting behavior of most vectors of avian malaria parasites. Instead, the geographic distribution of individual parasite lineages in diverse hosts suggests that species formation is predominantly allopatric and involves host expansion followed by local host-pathogen coevolution and secondary sympatry, resulting in local shifting of parasite lineages across hosts.
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Project description:Hybrid zones have been described as natural laboratories by researchers who study speciation and the various mechanisms that may affect gene flow. The evolutionary consequences of hybridization depend not only on reproductive compatibility between sympatric species, but also on factors like vulnerability to each other's predators and parasites. We examined infection patterns of the blood parasite Haemoproteus lophortyx, a causative agent of avian malaria, at a site in the contact zone between California quail (Callipepla californica) and Gambel's quail (C. gambelii). Controlling for the potential influence of sex and year, we tested whether species identity predicted infection status and intensity. We found that infection prevalence was lower in California and hybrid quail compared with Gambel's quail. However, infected California and hybrid quail had higher infection intensities than Gambel's quail. California and hybrid quail exhibited no significant differences in prevalence or intensity of infection. These findings suggest that infection by H. lophortyx has the potential to influence species barrier dynamics in this system; however, more work is necessary to determine the exact evolutionary consequences of this blood parasite on hybridization.
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Project description:OBJECTIVE:To assess the effects of protocolized recombinant human erythropoietin (r-HuEPO) therapy and standardized high dose iron supplementation on hematologic and iron status measures in a cohort of extremely low gestational age newborns (ELGANs). STUDY DESIGN:Charts of extremely low gestational age newborns admitted from 2006 to 2016 and who had received r-HuEPO per neonatal intensive care unit protocol were reviewed. The r-HuEPO was started at a dose of 900 IU/kg per week after 7 days of age and continued until 35 weeks postmenstrual age. Oral iron supplementation at 6-12 mg/kg per day was used to maintain a transferrin saturation of >20% during r-HuEPO treatment. Data on demographic features, hematologic and iron panel indices, red blood cell transfusions, and clinical outcomes were collected. Quartile groups were created based on serum ferritin levels at the conclusion of the r-HuEPO treatment and the quartiles were compared. RESULTS:The cohort included 116 infants with mean gestational age 25.8 ± 1.5 weeks and birth weight 793 ± 174.1 g. The r-HuEPO promoted erythropoiesis as indicated by increasing hemoglobin, hematocrit, and reticulocyte count. Serum ferritin decreased over time and was ≤75 ng/mL in 60.2% of infants at the conclusion of r-HuEPO therapy; 87% received packed red blood cell transfusions. Transfusion volume, total iron intake, total iron binding capacity, and transferrin concentration differed among infants in the different serum ferritin quartiles (P < .05). CONCLUSIONS:In extremely low gestational age newborns, r-HuEPO therapy promoted erythropoiesis. Despite a biomarker-based standardized high-dose iron supplementation, the majority of infants had evidence of iron deficiency to a degree that is associated with reduced brain function.
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Project description:INTRODUCTION: Intestinal schistosomiasis is widely distributed around Lake Victoria in Kenya where about 16 million people in 56 districts are at risk of the infection with over 9.1 million infected. Its existence in rural settings has been extensively studied compared to urban settings where there is limited information about the disease coupled with low level of awareness. This study therefore assessed community awareness on existence, signs and symptoms, causes, transmission, control and risk factors for contracting schistosomiasis as well as attitudes, health seeking behaviour and environmental antecedents that affect its control so as to identify knowledge gaps that need to be addressed in order to strengthen schistosomiasis control interventions in informal urban settings. METHODS: The study was carried out in an informal urban settlement where the prevalence of intestinal schistosomiasis was previously reported to be the highest (36%) among the eight informal settlements of Kisumu city. The study adopted cross-sectional design and purposive sampling technique. Eight focus group discussions were conducted with adult community members and eight key informant interviews with opinion leaders. Data was audio recorded transcribed, coded and thematically analyzed using ATLAS.ti version 6 software. RESULTS: Most respondents stated having heard about schistosomiasis but very few had the correct knowledge of signs and symptoms, causes, transmission and control of schistosomiasis. However, there was moderate knowledge of risk factors and at high risk groups. Their attitudes towards schistosomiasis and its control were generally indifferent with a general belief that they had no control over their environmental circumstances to reduce transmission. DISCUSSION/CONCLUSION: Although schistosomiasis was prevalent in the study area, majority of the people in the community had low awareness. This study, therefore, stresses the need for health education to raise community's awareness on schistosomiasis in such settings in order to augment prevention, control and elimination efforts.
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