Prominent human health impacts from several marine microbes: history, ecology, and public health implications

The One Health concept for the threat of severe acute respiratory syndrome coronavirus-2 to marine ecosystems

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global health threat. This virus is the causative agent for coronavirus disease 2019 (COVID-19). Pandemic prevention is best addressed through an integrated One Health (OH) approach. Understanding zoonotic pathogen fatality and spillover from wildlife to humans are effective for controlling and preventing zoonotic outbreaks. The OH concept depends on the interface of humans, animals, and their environment. Collaboration among veterinary medicine, public health workers and clinicians, and veterinary public health is necessary for rapid response to emerging zoonotic pathogens. SARS-CoV-2 affects aquatic environments, primarily through untreated sewage. Patients with COVID-19 discharge the virus in urine and feces into residential wastewater. Thus, marine organisms may be infected with SARS-CoV-2 by the subsequent discharge of partially treated or untreated wastewater to marine waters. Viral loads can be monitored in sewage and surface waters. Furthermore, shellfish are vulnerable to SARS-CoV-2 infection. Filter-feeding organisms might be monitored to protect consumers. Finally, the stability of SARS-CoV-2 to various environmental factors aids in viral studies. This article highlights the presence and survival of SARS-CoV-2 in the marine environment and its potential to enter marine ecosystems through wastewater. Furthermore, the OH approach is discussed for improving readiness for successive outbreaks. This review analyzes information from public health and epidemiological monitoring tools to control COVID-19 transmission.

A baseline study of spatial variability of bacteria (total coliform, E. coli, and Enterococcus spp.) as biomarkers of pollution in ten tropical Atlantic beaches: concern for environmental and public health

Coastal water quality in urban cities is increasingly impacted by human activities such as agricultural runoff, sewage discharges, and poor sanitation. However, environmental factors controlling bacteria abundance remain poorly understood. The study employed multiple indicators to assess ten beach water qualities in Ghana during minor wet seasons. Environmental parameters (e.g. temperature, electrical conductivity, total dissolved solids) were measured in situ using the Horiba multiple parameter probe. Surface water samples were collected to measure total suspended solids, nutrients, and chlorophyll-a via standard methods and bacteria determination through membrane filtration. Environmental parameters measured showed no significant variation for the sample period. However, bacteria loads differ significantly (p = 0.024) among the beaches and influenced significantly by nitrate (55.3%, p = 0.02) and total dissolved solids (17.1%, p = 0.017). The baseline study detected an increased amount of total coliforms and faecal indicator bacteria (Escherichia coli and Enterococcus spp.) in beach waters along the coast of Ghana, suggesting faecal contamination, which can pose health risks. The mean ± standard deviations of bacteria loads in beach water are total coliforms (4.06 × 10³ ± 4.16 × 10³ CFU/100 mL), E. coli (7.06 × 10² ± 1.72 × 10³ CFU/100 mL), and Enterococcus spp. (6.15 × 10² ± 1.75 × 10³ CFU/100 mL). Evidence of pollution calls for public awareness to prevent ecological and health-related risks and policy reforms to control coastal water pollution. Future research should focus on identifying the sources of contamination in the tropical Atlantic region.

Cyanobacterial Neurotoxin Beta-Methyl-Amino-l-Alanine Affects Dopaminergic Neurons in Optic Ganglia and Brain of Daphnia magna

The non-proteinogenic amino acid beta-methyl-amino-l-alanine (BMAA) is a neurotoxin produced by cyanobacteria. BMAA accumulation in the brain of animals via biomagnification along the food web can contribute to the development of neurodegenerative diseases such as Amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC), the latter being associated with a loss of dopaminergic neurons. Daphnia magna is an important microcrustacean zooplankton species that plays a key role in aquatic food webs, and BMAA-producing cyanobacteria often form part of their diet. Here, we tested the effects of BMAA on putative neurodegeneration of newly identified specific dopaminergic neurons in the optic ganglia/brain complex of D. magna using quantitative tyrosine-hydroxylase immunohistochemistry and fluorescence cytometry. The dopaminergic system was analysed in fed and starved isogenic D. magna adults incubated under different BMAA concentrations over 4 days. Increased BMAA concentration showed significant decrease in the stainability of dopaminergic neurons of D. magna, with fed animals showing a more extreme loss. Furthermore, higher BMAA concentrations tended to increase offspring mortality during incubation. These results are indicative of ingested BMAA causing neurodegeneration of dopaminergic neurons in D. magna and adversely affecting reproduction. This may imply similar effects of BMAA on known human neurodegenerative diseases involving dopaminergic neurons.

Culture-dependent bacteria in commercial fishes: Qualitative assessment and molecular identification using 16S rRNA gene sequencing

Fish contamination has been extensively investigated along the Saudi coasts, but studies pertaining to bacterial pathogens are scarce. We conducted qualitative assessment and molecular identification of culture-dependent bacteria in 13 fish species from three coastal sites and a local fish market in Jeddah, Saudi Arabia. Bacterial counts of gills, skin, gut and muscle were examined on agar plates of Macconkey’s (Mac), Eosin Methylene Blue (EMB) and Thiosulfate Citrate Bile Salts (TCBS) culture media. Bacterial counts significantly differed between species, sources and feeding habits of examined fishes. Mugil cephalus exhibited higher counts on TCBS (all body parts), Mac (gills, muscle and gut) and EMB (gills and muscle). Fishes from Area I had higher bacterial loads, coinciding with those in seawater and sediment from the same site, indicating direct association between habitat conditions and the levels of bacterial contamination. By feeding habit, detritivorous fish harbored higher counts than herbivorous and carnivorous species. Bacterial counts of skin were higher in fish from market than field sites, and positively correlated with other body parts indicating the relation of surface bacterial load on the overall quality of fish. Rahnella aquatilis (Enterobacteriaceae) and Photobacterium damselae (Vibrionaceae) were among the dominant species from fish muscle based on 16S rRNA sequencing. These species are known human pathogens capable of causing foodborne illness with severe antibiotic resistance. Opportunistic pathogens, e.g. Hafnia sp. (Enterobacteriaceae) and Pseudomonas stutzeri (Pseudomonadaceae) also occurred in fish muscle. The inclusion of bacterial contamination in future monitoring efforts is thus crucial.

Health impacts from cyanobacteria harmful algae blooms: Implications for the North American Great Lakes

Harmful cyanobacterial blooms (cHABs) have significant socioeconomic and ecological costs, which impact drinking water, fisheries, agriculture, tourism, real estate, water quality, food web resilience and habitats, and contribute to anoxia and fish kills. Many of these costs are well described, but in fact are largely unmeasured. Worldwide cHABs can produce toxins (cyanotoxins), which cause acute or chronic health effects in mammals (including humans) and other organisms. There are few attempts to characterize the full health-related effects other than acute incidences, which may go unrecorded. At present these are difficult to access and evaluate and may be ascribed to other causes. Such information is fundamental to measure the full costs of cHABs and inform the need for often-costly management and remediation. This paper synthesizes information on cHABs occurrence, toxicology and health effects, and relates this to past and current conditions in the Great Lakes, a major global resource which supplies 84% of the surface water in North America. This geographic region has seen a significant resurgence of cHABs since the 1980s. In particular we focus on Lake Erie, where increased reporting of cHABs has occurred from the early 1990's. We evaluate available information and case reports of cHAB-related illness and death and show that cHABs occur throughout the basin, with reports of animal illness and death, especially dogs and livestock. Lake Erie has consistently experienced cHABs and cyanotoxins in the last decade with probable cases of human illness, while the other Great Lakes show intermittent cHABs and toxins, but no confirmed reports on illness or toxicity. The dominant toxigenic cyanobacterium is the genus Microcystis known to produce microcystins. The presence of other cyanotoxins (anatoxin-a, paralytic shellfish toxins) implicates other toxigenic cyanobacteria such as Anabaena (Dolichospermum) and Lyngbya.

Neuroprotective role of sphingosine-1-phosphate in L-BMAA treated neuroblastoma cells (SH-SY5Y)

Sphingosine-1-phosphate (S1P) is a bioactive lipid which regulates proliferation, cell migration, survival and differentiation by specific receptors activation. We studied its effects on L-BMAA treated neuroblastoma cells (SH-SY5Y), an amino acid that can trigger neurodegenerative diseases such as amyotrophic lateral sclerosis/Parkinson dementia complex (ALS/PDC). We found that S1P protects from necrosis and prevents the GSK3 increasing as long as the PI3K/AKT pathway is active. Moreover, GSK3 inhibition protects against neuronal death caused by L-BMAA.

The epidemiology of ALS: a conspiracy of genes, environment and time

Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disease of motor neurons, resulting in worsening weakness of voluntary muscles until death from respiratory failure occurs after about 3 years. Although great advances have been made in our understanding of the genetic causes of ALS, the contribution of environmental factors has been more difficult to assess. Large-scale studies of the clinical patterns of ALS, individual histories preceding the onset of ALS, and the rates of ALS in different populations and groups have led to improved patient care, but have not yet revealed a replicable, definitive environmental risk factor. In this Review, we outline what is currently known of the environmental and genetic epidemiology of ALS, describe the current state of the art with respect to the different types of ALS, and explore whether ALS should be considered a single disease or a syndrome. We examine the relationship between genetic and environmental risk factors, and propose a disease model in which ALS is considered to be the result of environmental risks and time acting on a pre-existing genetic load, followed by an automatic, self-perpetuating decline to death.