A review of the factors causing paralysis in wild birds: Implications for the paralytic syndrome observed in the Baltic Sea

Geographical association of biodiversity with cancer and cardiovascular mortality rates: analysis of 39 distinct conditions

Background

Biodiversity has been recognized as a positive contributor to human health and wellbeing. Cardiovascular disease and cancer are the two most significant global health burdens, and understanding their relationship with biodiversity forms an essential step toward promoting biodiversity conservation and human health.

Methods

The species richness of birds is a common indicator of biodiversity, given their vast numbers, distinctive distribution, and acute sensitivity to environmental disturbances. This ecological study utilized avian observation data derived from the eBird database, human health data from the International Health Metrics and Evaluation, and county-level statistics, including population characteristics, socio-economics, healthcare service, residential environment, and geographic and climatic characteristics in 2014. We aimed to extensively explore the individual associations between biodiversity (i.e., avian species richness) and age-standardized cause-specific mortalities for different types of cancers (29 conditions) and cardiovascular diseases (10 conditions) across the United States (US).

Results

Our multiple regression analyses that adjusted for a variety of socio-demographic and geographical factors showed that increased rarefied species richness of birds was associated with reduced mortality rates for three of the five most common cancers, namely, tracheal, bronchus, and lung cancer, breast cancer (in women only), and colon and rectal cancer. For cardiovascular conditions, a similar relationship was observed for ischemic heart disease and cerebrovascular disease-the two most frequent causes of mortality. This study provided extended details regarding the beneficial effects of biodiversity on human health.

Mercury contamination and potential health risks to Arctic seabirds and shorebirds

Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, representing a larger portion of the Arctic than during previous AMAP assessments now also including parts of the Russian Arctic. To assess risk to birds, we used Hg toxicity benchmarks established for blood and converted to egg, liver, and feather tissues. Several Arctic seabird populations showed Hg concentrations that exceeded toxicity benchmarks, with 50 % of individual birds exceeding the "no adverse health effect" level. In particular, 5 % of all studied birds were considered to be at moderate or higher risk to Hg toxicity. However, most seabirds (95 %) were generally at lower risk to Hg toxicity. The highest Hg contamination was observed in seabirds breeding in the western Atlantic and Pacific Oceans. Most Arctic shorebirds exhibited low Hg concentrations, with approximately 45 % of individuals categorized at no risk, 2.5 % at high risk category, and no individual at severe risk. Although the majority Arctic-breeding seabirds and shorebirds appeared at lower risk to Hg toxicity, recent studies have reported deleterious effects of Hg on some pituitary hormones, genotoxicity, and reproductive performance. Adult survival appeared unaffected by Hg exposure, although long-term banding studies incorporating Hg are still limited. Although Hg contamination across the Arctic is considered low for most bird species, Hg in combination with other stressors, including other contaminants, diseases, parasites, and climate change, may still cause adverse effects. Future investigations on the global impact of Hg on Arctic birds should be conducted within a multi-stressor framework. This information helps to address Article 22 (Effectiveness Evaluation) of the Minamata Convention on Mercury as a global pollutant.

Paralytic and Amnesic Shellfish Toxins Impacts on Seabirds, Analyses and Management

Marine biotoxins have been frequently implicated in morbidity and mortality events in numerous species of birds worldwide. Nevertheless, their effects on seabirds have often been overlooked and the associated ecological impact has not been extensively studied. On top of that, the number of published studies confirming by analyses the presence of marine biotoxins from harmful algal blooms (HABs) in seabirds, although having increased in recent years, is still quite low. This review compiles information on studies evidencing the impact of HAB toxins on marine birds, with a special focus on the effects of paralytic and amnesic shellfish toxins (PSTs and ASTs). It is mainly centered on studies in which the presence of PSTs and/or ASTs in seabird samples was demonstrated through analyses. The analytical techniques commonly employed, the tissues selected and the adjustments done in protocols for processing seabird matrixes are summarized. Other topics covered include the role of different vectors in the seabird intoxications, information on clinical signs in birds affected by PSTs and ASTs, and multifactorial causes which could aggravate the syndromes. Close collaboration between seabird experts and marine biotoxins researchers is needed to identify and report the potential involvement of HABs and their toxins in the mortality events. Future studies on the PSTs and ASTs pharmacodynamics, together with the establishment of lethal doses in various seabird species, are also necessary. These studies would aid in the selection of the target organs for toxins analyses and in the postmortem intoxication diagnoses.

Mortality in Common (Sterna hirundo) and Sandwich (Thalasseus sandvicensis) Terns Associated with Bisgaard Taxon 40 Infection on Marco Island, Florida, USA

Widely distributed aquatic species such as terns are highly dependent on, and can serve as indicators of, the global health of marine and other aquatic environments. Documented mass mortality events in terns have been associated with anthropogenic, weather-related and, less commonly, infectious causes. This study describes a multispecies mortality event associated with brevetoxicosis and Bisgaard taxon 40-induced sepsis involving common (Sterna hirundo) and sandwich (Thalasseus sandvicensis) terns off the southwest coast of Florida, USA, in November and December 2018. During an approximately 6-8-week period, a large number of birds were found dead or displayed weakness, ataxia or other neurological signs. Many were admitted to a wildlife hospital for evaluation, but most died or were euthanized due to poor prognosis. Necropsy of 12 birds revealed minimal or non-specific gross lesions. Initial toxicology screening of tissues for brevetoxins revealed levels that could be consistent with brevetoxicosis. However, histology revealed multiorgan inflammation and necrosis associated with a gram-negative bacillus. A bacterium isolated on aerobic culture of liver and heart tissues was unidentifiable in the MALDI-TOF database. Subsequently, 16 S rRNA gene sequencing revealed that the isolate shared 99.33% homology with Bisgaard taxon 40 from the Pasteurellaceae family. While the source of the bacterium and potential association with brevetoxin exposure are unclear, histopathology suggests that the bacterium was the proximate cause of clinical signs and mortality in all birds examined as well as the scale of the mortality event. This report highlights the need to conduct detailed investigations into wildlife mortality events and expands on the current, limited knowledge of the effects of novel Pasteurellaceae bacteria on avian health.

Circulating trace elements: Comparison between early and late incubation in common eiders (Somateria mollissima) in the central Baltic Sea

We analyzed body mass and a panel of 64 trace elements in blood from incubating common eiders (Somateria mollissima) in the central Baltic Sea during the breeding seasons of 2017 (n = 27) and 2018 (n = 23). Using a non-invasive approach, the same incubating eiders nesting on Christiansø, Denmark were sampled once on day 4 and day 24 of incubation to provide a comparison between the early and late stages of incubation. Blood concentrations of chemical elements were quantified using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). Cadmium and lead significantly increased over the course of the incubation period while body mass, barium, calcium, cerium, cesium, iron, magnesium, manganese, molybdenum, phosphorus, selenium, strontium, sulfur, uranium, and zinc all significantly decreased. Excluding lead, all trace elements were within expected ranges. Lead blood concentrations had a 4.7-fold increase from 2017 to 2018 indicating a potential health threat. However, internal interactions between trace elements must be considered when making comparisons to toxicological thresholds. Body mass and many essential elements showed significantly higher levels in 2017 than 2018, which could be an indication of limitations in preferred food availability or harsher fasting conditions. Additional sampling years are needed to further investigate if these results reflect yearly fluctuations or decreasing health within the Christiansø eider colony. There was little overlap in element blood concentrations and body mass between days of incubation, indicating these parameters are affected by the physiological processes of reproduction and incubation. We recommend continued biomonitoring and use of complete trace element analysis for the Christiansø eiders to further understand year-to-year variations within colonies. Further investigation into the spatial ecology of the colony is also needed to provide a more robust understanding of exposure and source identification of trace elements.

Body mass, mercury exposure, biochemistry and untargeted metabolomics of incubating common eiders (Somateria mollissima) in three Baltic colonies

The Baltic/Wadden Sea Flyway of common eiders has declined over the past three decades. Multiple factors such as contaminant exposure, global warming, hunting, white-tailed eagle predation, decreased agricultural eutrophication and infectious diseases have been suggested to explain the decline. We collected information on body mass, mercury (Hg) concentration, biochemistry and untargeted metabolomics of incubating birds in two colonies in the Danish Straits (Hov Røn, n = 100; Agersø, n = 29) and in one colony in the Baltic proper (Christiansø, n = 23) to look into their metabolisms and energy balance. Body mass was available from early and late incubation for Hov Røn and Christiansø, showing a significant decline (25-30%) in both colonies with late body mass at Christiansø being the lowest. Whole blood concentrations of total mercury Hg were significantly higher in birds at Christiansø in the east compared to Hov Røn in the west. All birds in the three colonies had Hg concentrations in the range of ≤1.0 μg/g ww, which indicates that the risk of effects on reproduction is in the no to low risk category for wild birds. Among the biochemical measures, glucose, fructosamine, amylase, albumin and protein decreased significantly from early to late incubation at Hov Røn and Christiansø, reflecting long-term fastening as supported by the decline in body mass. Untargeted metabolomics performed on Christiansø eiders revealed presence of 8,433 plasma metabolites. Of these, 3,179 metabolites changed significantly (log₂-fold change ≥1, p ≤ 0.05) from the early to late incubation. For example, smaller peptides and vitamin B₂ (riboflavin) were significantly down-regulated while 11-deoxycorticosterone and palmitoylcarnitine were significantly upregulated. These results show that cumulative stress including fasting during incubation affect the eiders' biochemical profile and energy metabolism and that this may be most pronounced for the Christiansø colony in the Baltic proper. This amplify the events of temperature increases and food web changes caused by global warming that eventually accelerate the loss in body weight. Future studies should examine the relationship between body condition, temperature and reproductive outcomes and include mapping of food web contaminant, energy and nutrient content to better understand, manage and conserve the populations.

Seroprevalence of avian influenza in Baltic common eiders (Somateria mollissima) and pink-footed geese (Anser brachyrhynchus)

Blood plasma was collected during 2016-2018 from healthy incubating eiders (Somateria molissima, n = 183) in three Danish colonies, and healthy migrating pink-footed geese (Anser brachyrhynchus, n = 427) at their spring roost in Central Norway (Svalbard breeding population) and their novel flyway through the Finnish Baltic Sea (Russian breeding population). These species and flyways altogether represent terrestrial, brackish and marine ecosystems spanning from the Western to the Eastern and Northern part of the Baltic Sea. Plasma of these species was analysed for seroprevalence of specific avian influenza A (AI) antibodies to obtain information on circulating AI serotypes and exposure. Overall, antibody prevalence was 55% for the eiders and 47% for the pink-footed geese. Of AI-antibody seropositive birds, 12% (22/183) of the eiders and 3% (12/427) of the pink-footed geese had been exposed to AI of the potentially zoonotic serotypes H5 and/or H7 virus. AI seropositive samples selected at random (n = 33) showed a low frequency of serotypes H1, H6 and H9. Future projects should aim at sampling and isolating AI virus to characterize dominant serotypes and virus strains (PCR). This will increase our understanding of how AI exposure may affect health, breeding and population viability of Baltic common eiders and pink-footed geese as well as the potential spill-over to humans (zoonotic potential).

Health effects from contaminant exposure in Baltic Sea birds and marine mammals: A review

Here we review contaminant exposure and related health effects in six selected Baltic key species. Sentinel species included are common eider, white-tailed eagle, harbour porpoise, harbour seal, ringed seal and grey seal. The review represents the first attempt of summarizing available information and baseline data for these biomonitoring key species exposed to industrial hazardous substances focusing on anthropogenic persistent organic pollutants (POPs). There was only limited information available for white-tailed eagles and common eider while extensive information exist on POP exposure and health effects in the four marine mammal species. Here we report organ-tissue endpoints (pathologies) and multiple biomarkers used to evaluate health and exposure of key species to POPs, respectively, over the past several decades during which episodes of significant population declines have been reported. Our review shows that POP exposure affects the reproductive system and survival through immune suppression and endocrine disruption, which have led to population-level effects on seals and white-tailed eagles in the Baltic. It is notable that many legacy contaminants, which have been banned for decades, still appear to affect Baltic wildlife. With respect to common eiders, changes in food composition, quality and contaminant exposure seem to have population effects which need to be investigated further, especially during the incubation period where the birds fast. Since new industrial contaminants continuously leak into the environment, we recommend continued monitoring of them in sentinel species in the Baltic, identifying possible effects linked to climate change, and modelling of population level effects of contaminants and climate change.

HINDLIMB PARALYSIS SYNDROME IN WILD CARNABY'S COCKATOOS (CALYPTORHYNCHUS LATIROSTRIS): A NEW THREAT FOR AN ENDANGERED SPECIES

Carnaby's Cockatoos (Calyptorhynchus latirostris) are in decline in SW Western Australia from several processes, including habitat loss and fragmentation. However, in recent years, a disease syndrome has also emerged as a significant population threat. Emerging diseases in wildlife have the potential for catastrophic effects on population numbers, especially if a species is experiencing existing pressure from other threatening processes. This article describes an investigation into a hindlimb paralysis syndrome that has occurred in the summer and autumn since 2012 in 84 wild Carnaby's Cockatoos. Recovery from the syndrome has been demonstrated in 21 of 33 cases when supportive therapy was applied. Although a definitive diagnosis has not been obtained, the hypothesized etiology is an organophosphate-induced delayed-onset neuropathy. The syndrome may indicate that interaction between the cockatoos and inland agricultural practices are affecting this migratory species in ways that are, so far, poorly understood.

Current Status of the Blue Butterfly in Fukushima Research

Adverse biological impacts of the Fukushima nuclear accident have been revealed using the pale grass blue butterfly, Zizeeria maha, since 2012, which were often considered incompatible with the conventional understanding of radiation biology. This discrepancy likely originates from different system conditions and methodologies. In this article, we first respond to comments from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) regarding our study; "technical errors" in unit usage and mathematical models noted by UNSCEAR are not errors but reflect our research philosophy not to introduce theoretical assumptions associated with unit conversion and mathematical fit. Second, we review our recent studies to support the original 2012 conclusions. Because the high morphological abnormality rate and small body size detected in Fukushima in 2011 have already ceased, likely through adaptive evolution, their present geographical distributions were investigated throughout Japan. Local populations showing relatively high abnormality rates and small body sizes were rare and basically restricted to Miyagi and its northern populations excluding the Fukushima populations, supporting the causal involvement of the accident. Lastly, we stress the importance of understanding the whole picture of the biological impacts of the Fukushima accident. In addition to the direct radiation impacts, indirect impacts through unknown radiation-associated mechanisms, such as immunological responses to insoluble particulate matter and nutritional deficiencies in plants and animals, would be in effect. Further environmental studies beyond conventional radiation biology and physics are necessary to understand the complex responses of organisms, including humans, to the Fukushima nuclear accident.

Single-tube nested PCR assay for the detection of avian botulism in cecal contents of chickens

This paper describes a novel diagnostic method for the detection of avian botulism caused by Clostridium botulinum type C and C/D, using single-tube nested PCR assay. This assay was developed to overcome the disadvantages of bioassays used in experiments with mice. Three primer pairs including an antisense primer were designed to target the N-terminal of the toxin gene from C. botulinum types C and C/D. The specificity of the PCR assay was confirmed by using 33 bacterial strains and chicken cecal contents from farms that experienced botulism outbreaks. The detection limit for purified DNA was 1.1 fg/μl, and for bacterial spores was 4.3 spores/200 mg of cecal contents. While checking for specificity of the PCR assay, the reactions with the templates form C. botulinum type C and C/D which were tested became positive, but the rest of the reactions turned negative. However, the results for all clinical samples (n = 8) were positive. The PCR assay results for cecal samples obtained from 300 healthy chickens (150 Korean native chickens and 150 broilers) were all negative. This assay is rapid and straightforward and evades ethical issues associated with mouse bioassay. Moreover, it is more economical than real-time PCR.

Fungal/mycotic diseases of poultry-diagnosis, treatment and control: a review

Fungal/mycotic diseases cause significant economic losses to the poultry industry either due to their direct infectious nature or due to production of mycotoxins, the secondary fungal metabolites produced in grains or poultry feed. Several fungi have created havoc in the poultry industry and some of them cause direct harm to human health due to their zoonotic implications. They are responsible for high morbidity and mortality, especially in young birds and cause stunted growth and diarrhea; and fatal encephalitis. Mycotic dermatitis is a possible health hazard associated with poultry houses. Mycotoxins are the leading cause of producing immunosuppression in birds, which makes them prone to several bacterial and viral infections leading to huge economic losses to the poultry industry. In comparison to bacterial and viral diseases, advances in diagnosis, treatment, prevention and control of fungal diseases in poultry has not taken much attention. Recently, molecular biological tools have been explored for rapid and accurate diagnosis of important fungal infections. Effective prevention and control measures include: appropriate hygiene, sanitation and disinfection, strict biosecurity programme and regular surveillance/monitoring of fungal infections as well as following judicious use of anti-fungal drugs. Precautionary measures during crop production, harvesting and storing and in feed mixing plants can help to check the fungal infections including health hazards of mycotoxins/mycotoxicosis. The present review describes the fungal pathogens causing diseases in poultry/birds, especially focusing to their diagnosis, prevention and control measures, which would help in formulating appropriate strategies to have a check and control on these unwanted troubles to the poultry producers/farmers.