High Public Health Risk Research Articles

Antimicrobial Resistance and Extended-Spectrum Beta-Lactamase Production in Enterobacteria Isolated from Free-Living Primates.

The aim of this study was to evaluate the profile of antimicrobial resistance in members of the family Enterobacteriaceae and to detect strains of extended-spectrum beta-lactamases (ESBL) in free-living Sapajus nigritus. Oral and rectal swabs were collected from 15 primates to isolate and identify bacteria, conduct phenotypic tests to detect antimicrobial sensitivity and ESBL-producing strains, and calculate the multiple antimicrobial resistance index. The least effective antimicrobial was amoxicillin (72.72%) and ampicillin (57.57%), and the samples were considered as high risk for public health. No sample was positive for ESBL production. The results show that this study is relevant to One Health initiatives, considering the possibility of transmission of bacterial resistance and resistant genes originating from direct or indirect interaction of S. nigritus with parkgoers. However, these animals cannot be considered as the only reservoirs and transmitters of resistant bacteria as they can be contaminated by human-origin bacteria that can be extremely harmful and often prove lethal to them that play an important role in relationship to the ecology, spreading seeds and controlling insects.

Impact Assessment of Groundwater Quality using WQI and Geospatial tools: A Case Study of Islamkot, Tharparkar, Pakistan

Groundwater is the only source of fresh water in the Thar Desert which is located in an arid region of Pakistan with dense population and spreads over 19,638km2. Low rainfall, low groundwater recharge, high evaporation and absence of perennial streams are the general reasons for water scarcity. Being the single water source for drinking, domestic and industrial uses, and livestock activities, this source is highly overexploited. Realizing the gravity of the situation, this paper presents a groundwater quality evaluation of Islamkot, Tharparkar, using Water Quality Index (WQI) and Geospatial tools. 40 samples were collected from dug wells. The TDS of 28 samples was found higher than 3000mg/L and 12 samples ranged from 1500 to 3000mg/L. Many (28) samples were not further analyzed due to their very high TDS which made the water unfit for drinking. Twelve samples with TDS ranging from 1500 to 3000 mg/L were further analyzed. The analyzed results revealed the average values of pH, EC, TDS, salinity, chloride, total alkalinity, fluoride, and arsenic. The results did not meet NEQS and WHO guidelines. Pearson correlation analysis was conducted among parameters. Further, groundwater quality was assessed by WQI and indicated that water quality varied from very poor to unsuitable for drinking. The consumption of polluted groundwater has been the main cause of prevalent waterborne diseases and poses a very high risk for public health

MERCURIO EN UN ARROYO ALTOANDINO CON ALTO IMPACTO POR MINERÍA AURÍFERA ARTESANAL (LA RINCONADA, PUNO, PERÚ)

La Rinconada, in the high Andes at southern Peru, is a town heavily engaged in artisanal gold mining, where tailings and waste are dumped into streams of river headwaters. For this reason, mercury was evaluated in surface water and sediments of the Lunar de Oro stream, in its origins at the Ananea glacier. Four points were sampled in the months of December 2014, and January and March 2015. In both segments, mercury was determined by atomic fluorescence spectrophotometry (EPA 245.2), and pH, dissolved oxygen, electrical conductivity, total dissolved solids and temperature were determined by multiparameter and in laboratory. In the four sampling points, mercury in water presented similar levels, with values between < 0.00005 and 0.00043 mg/L (n = 12), although in March, related to a lower flow, higher levels were determined (0.00034 ± 0.000032 mg/L), surpassing the Peruvian standards and the Canadian Environmental Quality Guidelines (CEQG); pH recorded an average of 3.44 ± 0.12 and oxygen 2.84 ± 0.23 mg/L, values that confirmed its low quality. Sediments showed values between 9 and 373 mg/kg, with no significant differences between zones and months, exceeding NOAA and CEQG limits for 100 % of the samples. Pollution rates confirmed that the site is extremely contaminated by mercury, corroborating its high risk for public health and the ecosystems involved.

Temporal dynamics of intra-and extra-cellular microcystins concentrations in Koka reservoir (Ethiopia): Implications for public health risk

This study was carried out with a view of understanding the temporal dynamics of microcystin concentrations in both algal seston and water samples and the associated public health risk. All the major MC variants, namely MC-LR, MC-YR, and MC-RR, were detected in both the algal seston and water samples. In the majority of the samples, the most potent variant, MC-LR, constituted the greatest proportion of the total MC concentration suggesting extremely high potential public health risk. The exceptionally high concentrations (μg L−1) of all the variants, MC-LR (815), MC-YR (466.6) and MC-RR (265.68), were observed in May. Although the extracellular MCs were relatively less concentrated and less frequently detected, concentrations (μg L−1) of up to 20 of MC-LR, 6.13 of MC-YR, and 1.27 MC-RR were encountered. The strong and significant association between Microcystis abundance and concentration of nitrate (Spearman Rank Order Correlation r = 0.793, p < 0.001) may suggest that nitrate is the key dictating factor in the dynamics of Microcystis, and may have consequently influenced the MC levels in the reservoir.

INDUSTRIAL ENTERPRISES AND HEALTH RISK CATEGORIES

In order to ensure the sanitary and epidemiological welfare of the population in the Russian Federation, measures are being taken to improve control and supervisory activities through the introduction of a risk-based approach to the organization of control and surveillance activities. At the base of the risk-based supervision, there is a differentiated approach to control and supervisory activities concentrating efforts on enterprises that pose Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeingeptable health risks. The potential danger of the facilities subject to federal state sanitary and epidemiological supervision in the Krasnoyarsk Territory was assessed with regard to the health risk criteria. In the Krasnoyarsk Territory, with taking into account types of economic activity, 40.83% of the industrial enterprises fall under the category of those involving extremely high, high and significant public health risk. 1.6% of the economic entities pose an extremely high health risk in the Krasnoyarsk Territory as a whole and, with bearing in mind their activities, the percentage of such entities is slightly lower (1.48%). In terms of industrial enterprises’ activity, compared to other economic entities, the percentage of the enterprises posing extremely high risk is the highest and amounts to 4.37%. Such a prevailing ratio is typical for high-risk enterprises - 7.05%; 6.7% and 12.65% respectively, with approximately the same ratio of the enterprises posing a significant risk - 23.14%; 22.79% and 23.81% respectively. When assessing the total risk created by the economic entities of the Krasnoyarsk Territory with the consideration of their types of activity, the contribution of the enterprises posing extremely high risk was found to be 80.11%, and when considering risks related to the activities of industrial enterprises, the share of such facilities increases to 92.6%. In the Krasnoyarsk Territory, industrial enterprises are the main factor affecting the environmental quality, and therefore it becomes important to actively use the social and hygienic monitoring system as part of state control over the activities of industrial enterprises, the system that provides data on environmental factors and health status to be applied by the system of environmental management and public health.

Carcinogenic risk assessment in population living in the ecologically problematic areas of Irkutsk region

Irkutsk region is among territories of intense industrial development. Considerable part of the regional population is long exposed to chemical pollutants of environmental objects. Th e authors evaluated carcinogenic risk for the population of industrial centers and rural area. Findings are that maximal carcinogenic risk is carried by the urban population. Aggregated carcinogenic risk parameters evaluation proved inhalation to be a priority route of exposure. Irkutsk region appeared to have territories with high carcinogenic risk for public health. Among a list of chemicals in the ambient air are priority carcinogens: six-valent chromium and lead. The evidences necessitate measures on the risks minimization. Due to absent data on carcinogens content of drinkable water in some rural area, the necessity is to evaluate risk for the rural population by studies of drinkable water quality that does not match hygienic regulations, because oral one is a main route of carcinogens intake.

Genetic Compatibility of Reassortants between Avian H5N1 and H9N2 Influenza Viruses with Higher Pathogenicity in Mammals.

The cocirculation of H5N1 and H9N2 avian influenza viruses in birds in Egypt provides reassortment opportunities between these two viruses. However, little is known about the emergence potential of reassortants derived from Egyptian H5N1 and H9N2 viruses and about the biological properties of such reassortants. To evaluate the potential public health risk of reassortants of these viruses, we used reverse genetics to generate the 63 possible reassortants derived from contemporary Egyptian H5N1 and H9N2 viruses, containing the H5N1 surface gene segments and combinations of the H5N1 and H9N2 internal gene segments, and analyzed their genetic compatibility, replication ability, and virulence in mice. Genes in the reassortants showed remarkably high compatibility. The replication of most reassortants was higher than the parental H5N1 virus in human cells. Six reassortants were thought to emerge in birds under neutral or positive selective pressure, and four of them had higher pathogenicity in vivo than the parental H5N1 and H9N2 viruses. Our results indicated that H5N1-H9N2 reassortants could be transmitted efficiently to mammals with significant public health risk if they emerge in Egypt, although the viruses might not emerge frequently in birds.IMPORTANCE Close interaction between avian influenza (AI) viruses and humans in Egypt appears to have resulted in many of the worldwide cases of human infections by both H5N1 and H9N2 AI viruses. Egypt is regarded as a hot spot of AI virus evolution. Although no natural reassortant of H5N1 and H9N2 AI viruses has been reported so far, their cocirculation in Egypt may allow emergence of reassortants that may present a significant public health risk. Using reverse genetics, we report here the first comprehensive data showing that H5N1-N9N2 reassortants have fairly high genetic compatibility and possibly higher pathogenicity in mammals, including humans, than the parental viruses. Our results provide insight into the emergence potential of avian H5N1-H9N2 reassortants that may pose a high public health risk.

Virulence factors and integrons are associated with MDR and XDR phenotypes in nosocomial strains of Pseudomonas aeruginosa in a Venezuelan university hospital.

ABSTRACTMultidrug resistance (MDR), virulence and transferable elements potentiate Pseudomonas aeruginosa's role as an opportunistic pathogen creating a high risk for public health. In this study, we evaluated the possible association of multidrug resistance, virulence factors and integrons with intrahospital P. aeruginosa strains isolated from patients at Cumana hospital, Venezuela. Relevant clinical-epidemiological data were collected to study 176 strains (2009-2016) isolated from different hospital units. Bacterial resistance was classified as susceptible, low-level resistant (LDR), multidrug resistant (MDR) and extensively drug-resistant (XDR). Most strains produced pyoverdine, DNase, gelatinase and hemolysin. Around 73% of the strains showed some type of movement. MDR and XDR strains increased from 2009 (24.2% and 4.8%, respectively) to 2016 (53.1% and 18.8%); while LDR decreased from 64.5% to 6.3%. The exoU and exoS genes were found in a significant number of strains (38.1 and 7.4%, respectively). Class I integrons were detected in 35.8% of the strains and the frequency was associated with resistance (42.9, 22.4, 41.4 and 61.9%, for susceptible, LDR, MDR and XDR, respectively). The MDR/XDR strains were positively associated with hemolysins and exoU, but negatively associated with bacterial twitching. MDR/XDR phenotypes were also associated with the Intensive Care Unit (ICU), septicemia, bronchial infection and diabetic foot ulcers, as well as long hospital stay (≥10 days) and previous antimicrobial treatment. High frequency of MDR/XDR strains and their association with class I integrons and virulence factors can increase the infection potential, as well as morbidity and mortality of patients attending this hospital and could spread infection to the community, creating a health risk for the region.

Human-pathogenic Anaplasma spp., and Rickettsia spp. in animals in Xi'an, China.

In China, thirteen species of tick-borne rickettsiales bacteria pathogenic to human have been reported in ticks and host animals, and human patients caused by them also has been identified. However, investigation for rickettsiales bacteria circulating in Xi’an wasn’t performed although diseases resembling human diseases caused by these organisms have been found. In this study, domestic animals and ticks in Xi’an, China, were tested for the presence of rickettsiales bacteria pathogenic to humans. Besides A. ovis, a high prevalence of A. capra was observed suggesting a high public health risk exists. In addition, two novel Anaplasma species closely related to A. phagocytophilum were identified and formed distinct lineages in the phylogenetic trees, with more than 98.3% identities for rrs gene, while divergences up to 20.2% and 37.0% for groEL and gltA genes, respectively. Both of these two novel Anaplasma species were found to circulate in goats and further assessment of their pathogenicity is needed. Ca. R. jingxinensis, with potential pathogenicity, was also detected in H. longicomis ticks with high prevalence. However, other causative agents were not identified although they were distributed in other areas of China.

Prevalence and Antibiotic Resistance of Listeria monocytogenes Isolated from Ready-to-Eat Foods in Turkey

The aim of the present study was the determination of the prevalence and antibiotic resistance of L. monocytogenes in ready-to-eat (RTE) foods in Ankara, Turkey. In order to detect and isolate L. monocytogenes from 201 RTE food samples, the EN ISO 11290:1 method was used. All isolates were identified using the polymerase chain reaction. The strains were also confirmed by the detection of the hemolysin gene (hlyA). The overall prevalence of L. monocytogenes was 8.5% among the food samples. Seventeen L. monocytogenes strains were examined by the disk diffusion assay for their resistance to 23 antibiotics. All strains were susceptible to erythromycin, clarithromycin, streptomycin, gentamicin, vancomycin, imipenem, trimethoprim, and chloramphenicol, while all strains were resistant to nalidixic acid, ampicillin, penicillin G, linezolid, and clindamycin. The higher resistance was found against oxacillin (94.1%), kanamycin (76.5%), levofloxacin (70.6%), and teicoplanin (64.7%), followed by amoxicillin/clavulanic acid (53.0%), rifampicin (47.1%), and ciprofloxacin (35.3%). A lower incidence of resistance was observed against tetracycline (5.9%), meropenem (5.9%), and trimethoprim/sulfamethoxazole (17.7%). All isolates were multidrug resistant showing resistance to at least three antibiotic classes. High L. monocytogenes prevalence among analyzed RTE foods represents a high risk for public health. Our findings show a high prevalence of L. monocytogenes in RTE foods in Turkey. More effective control strategies for L. monocytogenes are needed to reduce both prevalence and resistance of L. monocytogenes in Turkish RTE foods.

Overview on the Mycotoxins Incidence in Serbia in the Period 2004⁻2016.

With an average annual production of 6.9 M tonnes and 2.5 M tonnes of maize and wheat respectively, Serbia is one of the main grain producers and exporters in Europe. Cereals are also the major staple food in Serbian diet. In view of the high cereal consumption, for human and animal nutrition, the presence of mycotoxins entails a high public health risk of chronic exposure to mycotoxins. This study provides an overview of the incidence of predominant mycotoxins, mainly in cereal and dairy products, in Serbia, in the 2004–2016, using data reported in the scientific literature. The study demonstrated that the total prevalence of aflatoxins was 62.9% (n = 12,517) with 26.2% of the samples exceeding the EU limits during this period. Results obtained for T-2/HT-2 (n = 523), deoxynivalenol (n = 2907), fumonisins (n = 998), zearalenone (n = 689) and ochratoxin A (n = 740) indicated the prevalence of 45.5%, 42.9%, 63.3%, 39.3% and 28.1%, respectively. For these mycotoxins, the EU limits were less frequently exceeded. Comprehensive collection and analysis of all accessible information reviewed in this paper showed moderate incidence and prevalence of mycotoxins in Serbia, with an exception of the 2012 drought year and the 2014 flood year.

Anaplasma sp., Ehrlichia sp., and Rickettsia sp. in Ticks: A High Risk for Public Health in Ibagué, Colombia

Anaplasma sp., Ehrlichia sp., and Rickettsia sp. in Ticks: A High Risk for Public Health in Ibagué, Colombia

Prevalence and Risk Factors of Coxiella burnetii Antibodies in Bulk Milk from Cattle, Sheep, and Goats in Jordan

This large-scale cross-sectional study was conducted to determine the prevalence, geographical distribution, and risk factors for the presence of antibodies against Coxiella burnetii in bulk tank milk derived from dairy cattle, sheep, and goats in Jordan. Bulk milk samples were collected from 78 dairy cattle, 48 sheep, and 23 goat farms from various places in Jordan according to the density of these animal species in each region of the country. The samples were tested for C. burnetii antibodies using the CHEKIT Q-Fever Antibody ELISA kit. A standardized questionnaire was also used to collect data from each farm to identify and rank the risk factors for the presence of C. burnetii antibodies. The results revealed that 62.9% (95% confidence interval: 55.1 to 70.0%) of the tested ruminant farms were positive for C. burnetii antibodies. Positive results were obtained from 70.9% (60.6 to 79.5%) of dairy cattle farms, 52.1% (38.3 to 65.5%) of sheep farms, and 56.0% (37.1 to 73.3%) of goat farms. Six factors were associated with the presence of these antibodies on cattle farms, and five factors were associated with these antibodies on sheep and goat farms (chi-square test). The multivariate logistic regression model revealed that large dairy cattle farms, farms that add new animals to the herd, farms that infrequently clean the feeders, and farms in particular areas are 28.6, 19.9, 8.0, and 6.4 times more likely, respectively, to have animals with C. burnetii antibodies. Sheep and goat farms that mix their animals with those from other farms, graze more than 5 km, and infrequently sanitize the feeders were 8.0, 0.06, and 13.6 times more likely, respectively, to have animals with C. burnetii antibodies. These data reveal the widespread exposure of Jordanian ruminants to C. burnetii and suggest a high risk for public health.

Cancer Drug Development and the Evolving Regulatory Framework for Companion Diagnostics in the European Union

The European Union (EU) legal framework for medical device regulation is currently under revision. The European Commission has proposed a new framework to ensure that medical devices serve the needs and ensure the safety of European citizens, aiming for a framework that is fit for purpose, more transparent, and better adapted to scientific and technological progress. The proposed new framework is described as an evolution of the current regime keeping the same legal approach. An important proposed change is that companion diagnostics will no longer be considered as low risk and subject to self-certification by the manufacturer. According to the new proposal, companion diagnostics will be classified as high individual risk or moderate public health risk (category C) and require conformity assessment by a notified body. It has also been proposed that evidence of the clinical utility of the device for the intended purpose should be required for companion diagnostics. In this article, we review the EU legal framework relevant for companion diagnostics, describe the proposed changes, and summarize the available scientific guidance from the European Medicines Agency and its regulatory experience with cancer drug development including companion diagnostics. See all articles in this CCR Focus section, "The Precision Medicine Conundrum: Approaches to Companion Diagnostic Co-development."

Utilization of Health Services and Health-Related Quality of Life Research of Rural-to-Urban Migrants in China: A Cross-Sectional Analysis

The number of China’s rural-to-urban migrants is increasing rapidly. Numerous rural-to-urban migrants have poor working and living conditions and lack local social security and support, so they are often faced with high public health risk, which is closely related to their health problems. In this study, we use the SF-36 scale to explore the rural-to-urban migrant health of Wuhan City. Gender, marital status, age, and residence register are the control variables. The different ways in dealing with their sickness, medical health service from companies for injuries, and selective tendency to medical institutions are three independent variables. We use descriptive statistical and regression analysis methods (ordinal logistics and stereotype ordinal) to explore the utilization of health services of rural-to-urban migrants and its effect on health-related quality of life (HRQOL). The score of the SF-36 Table shows that whether or not the companies provide medical care for injuries on the job has a very significant effect on the quality of life in the eight dimensions. The rural-to-urban migrants who see a doctor when they are sick have higher quality of life than those who do not; those who select city or county hospitals have higher quality of life than those who select primary hospitals. The costs and time consumed by medical treatment mainly affect their choice on whether or not they will seek medical attention and/or hospitals when they are sick. To a considerable extent, the utilization of health services remarkably affects HRQOL of rural-to-urban migrants. The quality of life on the SF-36 scale does not reflect the particularity of rural-to-urban migrants on health status and needs. However, based on further analysis of the data, improving the utilization and accessibility of health services for rural-to-urban migrants can guarantee their healthy life.

Epidemic Escherichia coli ST131 and Enterococcus faecium ST17 in Coastal Marine Sediments from an Italian Beach

Fecal indicator bacteria (FIB) are used worldwide to assess water quality in coastal environments, but little is known about their genetic diversity and pathogenicity. This study examines the prevalence, antimicrobial resistance, virulence, and genetic diversity of FIB isolated from marine sediments from a central Adriatic seaside resort. FIB, recovered from 6 out of 7 sites, were significantly more abundant at sampling stations 300 m offshore than close to the shore. Escherichia coli accounted for 34.5% of fecal coliforms, and Enterococcus faecalis accounted for 32% of enterococci. Most isolates (27% of E. coli and 22% of enterococci) were recovered from the sediments that had the highest organic content. Multidrug-resistant E. coli (31%) and enterococci (22%) were found at nearly all sites, whereas 34.5% of E. coli and 28% of enterococci harboring multiple virulence factors were recovered from just two sites. Pulsed-field gel electrophoresis typing showed wide genetic diversity among isolates. Human epidemic clones ( E. coli ST131 and Enterococcus faecium ST17) were identified for the first time by multilocus sequence typing in an area where bathing had not been prohibited. These clones were from sites far removed from riverine inputs, suggesting a wide diffusion of pathogenic FIB in the coastal environment and a high public health risk.

Assessment of potential contribution of official meat inspection and abattoir process hygiene to biological safety assurance of final beef and pork carcasses

The performances of current official meat inspection and abattoir process hygiene in assuring biological safety of final beef and pork carcasses were assessed through risk ranking of zoonotic hazards associated with cattle and pigs that each of these risk management strategies can control. Among hazards associated with cattle, Taenia saginata cysticercus, nontyphoidal Salmonella enterica, verotoxigenic Escherichia coli and prion causing bovine spongiform encephalopathy were found as posing medium risk for public health whilst all others were found as posing low or negligible risk. Among hazards associated with pigs, Trichinella, Toxoplasma gondii in outdoor pigs and Yersinia enterocolitica were found as posing medium risk and S. enterica was found as posing high risk for public health, whilst all others as posing low or negligible risk. Analysis of the current two main risk management strategies in cattle and pigs abattoirs indicated that abattoir process hygiene has a higher public health protection potential than official meat inspection. Nevertheless, each of these strategies currently plays an important role in controlling some meat safety hazards that cannot be controlled by the other, so both have to be applied simultaneously.

Ethnocentric approach to address South Asian health issues

South Asian populations have distinct healthcare requirements to other ethnic demographics. Epidemiologically they constitute a high-risk group for many public health diseases such as cardiovascular disease, chronic kidney disease and diabetes mellitus. Despite individuals of South Asian backgrounds encompassing many individual countries, cultures, religions and backgrounds they share many common health concerns that are poorly tackled in established models of healthcare delivery. To successfully address this burgeoning public health burden, it is important for healthcare professionals and providers to appreciate the need for an ethnocentric approach to South Asian health requirements. Key stakeholders need to understand the need for an integrated ethnocentric approach to challenge the poor health status of this population. Appreciation of the socio-cultural dimension to South Asian healthcare requirements should help guide targeted and focused strategies to improve the outlook for this unique population at high public health risk.

Public health risk status of the water supply frame work at Kwame Nkrumah (Postgraduate) Hall, University of Nigeria, Nsukka and environs

The aim of the study is to assess the public health risk status of the potable water supply framework at the Kwame Nkurumah Postgraduate Residence (PG) Hall, University of Nigeria, Nsukka, (UNN), Enugu State, Nigeria, and environs. Four potable water supply frame-works at the PG Hall, UNN, and exposed stagnant water were sampled and analysed in accordance with the Association of Official Analytical Chemists (AOAC) Official Method of Analysis to detect their limits of chemical and microbial constituents with high public health risk. The samples comprised of tap water (A), tap-to-reservoir water (B), commercial sachet water (C) commercial bottled water (D) and exposed stagnant water (E). The nitrate levels of all the sources (except ‘B’) were above the World Health Organisation (WHO) limit (10.00 mg/L). Thus they could cause methaemoglobinemia in infants. Nitrate content of ‘B’ (6.99 mg/L) was significantly (p < 0.05) low, relative to that of ‘A’ (23.08 mg/L); and indicated microbial action. The physicochemical and microbial quality of the tap water differed significantly (p < 0.05) from that of the tap-to-reservoir water. All the pH, except that of ‘D’, were below WHO recommended pH range (6.5 to 8.5) for drinking water. ‘D’ was more or less a mineral concentrate, as its chemical constituents were significantly (p < 0.05) higher than those of other samples. Total viable count (TVC) and coli form count of the reservoir water and sachet water (0.17 to 0.20 and 0.11 to 0.09 cfu/ml, respectively), indicated heavy microbial contamination. While ‘D’, was devoid of biological contamination. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were among the bacteria isolated. Taken together, the sampled potable water (except ‘A’ and ‘D’) was generally, of poor chemical and microbial quality; and may be considered unacceptable. Key words: Public health risk, potable water, physicochemical and microbial water quality, water pollution

Municipal wastewater treatment plants as removal systems and environmental sources of human-virulent microsporidian spores

Municipal wastewater treatment plants play a vital role in reducing the microbial load of sewage before the end-products are discharged to surface waters (final effluent) or local environments (biosolids). This study was to investigate the presence of human-virulent microsporidian spores (Enterocytozoon bieneusi, Encephalitozoon intestinalis, and Encephalitozoon hellem) and enterococci during treatment processes at four Irish municipal secondary wastewater treatment plants (plants A-D). Microsporidian abundance was significantly related to seasonal increase in water temperature. Plant A had the least efficient removal of E. intestinalis spores (32%) in wastewater, with almost 100% removal at other plants both in April and July. Some negative removal efficiencies were obtained for E. bieneusi (at plants C and D, -100%) and for E. hellem (at plants A and D, -90% and -50%). In addition, a positive correlation was found between the levels of enterococci and E. bieneusi in July (r (s) = 0.72, P < 0.05). In terms of the dewatered biosolids, a median concentration as high as 32,000 spores/Kg of E. hellem was observed at plant D in July. Plant C sewage sludge contained the lowest microsporidian loadings (E. bieneusi; 450 spores/L and 1,000 spores/L in April and July, respectively). This study highlights the seasonal variation in concentrations of microsporidian spores in the incoming sewage. Spores in final effluents and dewatered biosolids can be the source of human-virulent microsporidian contamination to the local environment. This emphasizes a considerably high public health risk when sewage-derived biosolids are spread during summer months. This study also suggested enterococci as a potential indicator of the presence of microsporidian spores in wastewater, especially for E. bieneusi.