Histopathological changes in two potential indicator fish species from a hyper-eutrophic freshwater ecosystem in South Africa : a baseline study

Histopatholigical changes were identified in selected target organs from two freshwater fish species, Clarias gariepinus and Oreochromis mossambicus, inhabiting a hyper-eutrophic freshwater aquatic system. The approach was to use a histology-based fish health assessment protocol which included a semi-quantitative histopathological assessment of six target organs (gills, liver, ovaries, testes, kidney, and heart). Results of water quality analysis showed selected variables to be above the recommended levels including pH, ammonia, nitrogen, chloride, and phosphorus. A number of histopathological alterations were identified in the target organs of both species, with the highest number observed in the liver. Species differences were identified in terms of the severity of the alterations within all the organs, with most alterations being regressive in nature. The results of this study provide valuable baseline data for two indicator species inhabiting a hyper-eutrophic system that could be useful for future bio-monitoring studies.The National Research Foundation of South Africahttp://tandfonline.com/loi/taas2

A histology-based fish health study on Clarias gariepinus in the Hartebeespoort Dam with the focus on reproduction

A qualitative and quantitative histological assessment was done on the liver, gills and gonads. Focus was placed on reproductive health aspects by staging the gonads according to their reproductive development and assessing the motility of activated sperm using Computer Assisted Sperm Analysis.This paper was initially delivered at the Annual Congress of the Biological Sciences Division of the South African Academy for Science and Art, ARC-Plant Protection Research Institute, Roodeplaat, Pretoria, South Africa on 01 October 2010.http://www.satnt.ac.zaam201

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

First report of the concentrations and implications of DDT residues in chicken eggs from a malaria–controlled area

In malaria-endemic areas, where DDT is still used for vector control by indoor residual spraying (IRS), the concentrations of DDT in human blood and breast milk are high, and there are indications of human health impacts. To identify the possible avenues of exposure reduction, we created the concept of a Total Homestead Environment Approach (THEA). THEA characterizes the interactions between DDT, humans, and the biota within and around homesteads. One dietary route of human exposure and uptake of DDT, namely, chicken egg consumption, has to our knowledge never been studied. The ΣDDT in eggs from a DDT-sprayed village ranged between 5200 and 48,000 ng/g wm (wet mass), with a median of 11,000 ng/g wm. On a lipid mass-basis (lm), the mean ΣDDT for eggs from the sprayed village was 100,000 ng/g lm. The maximum egg concentration observed was three orders of magnitude higher than the median. The acceptable daily intake (ADI) was not exceeded based on the consumption of three eggs per week for a 60 kg person. This equates to an intake of 0.089 g DDT per person per year. Chicken egg consumption is therefore a possible target for exposure reduction, probably best achieved by reducing the DDT concentrations in soil

DDT contamination from indoor residual spraying for malaria control

The insecticide DDT is still used in specific areas of South Africa for indoor residual spray (IRS) to control malaria vectors. Local residents could be exposed to residues of DDT through various pathways including indoor air, dust, soil, food and water. The aims of this study were to determine the levels of DDT contamination, as a result of IRS, in representative homesteads, and to evaluate the possible routes of human exposure. Two villages, exposed (DV) and reference (TV) were selected. Sampling was done two months after the IRS process was completed. Twelve homesteads were selected in DV and nine in TV. Human serum, indoor air, floor dust, outside soil, potable water, leafy vegetables, and chicken samples (muscle, fat and liver) were collected and analyzed for both the o,p′- and p,p′-isomers of DDT, DDD and DDE. DDT was detected in all the media analyzed indicating a combination of potential dietary and non-dietary pathways of uptake. DV had the most samples with detectable levels of DDT and its metabolites, and with the exception of chicken muscle samples, DV also had higher mean levels for all the components analyzed compared to TV. Seventy-nine percent of participants from DV had serum levels of DDT (meanΣDDT 7.3 μg g−1 lipid). These residues constituted mainly of p,p′-DDD and p,p′-DDE. ΣDDT levels were detected in all indoor air (mean ΣDDT 3900.0 ng m−3) and floor dust (meanΣDDT 1200.0 μg m−2) samples. Levels were also detected in outside soil (mean ΣDDT 25.0 μg kg−1) and potable water (mean ΣDDT 2.0 μg L−1). Vegetable sample composition (meanΣDDT 43.0 μg kg−1) constituted mainly p,p′-DDT and p,p′-DDD. Chicken samples were highly contaminated with DDT (muscle mean ΣDDT 700.0 μg kg−1, fat mean ΣDDT 240,000.0 μg kg−1, liver mean ΣDDT 1600.0 μg kg−1). The results of the current study raise concerns regarding the potential health effects in residents living in the immediate environment following DDT IRS

Intersex inferal indigenous fresh water Oreochromis mossambicus, from various parts in the Luvuvhu River, Limpopo Province, South Africa

This study reports on intersex in Oreochromis mossambicus, an indigenous fish species inhabiting most aquatic systems throughout South Africa (SA). Male fish were collected from three sites in the Luvuvhu River, Limpopo Province, SA:Albasini Dam (AD), Nandoni Dam(ND),and Xikundu Weir(XW). The latter two sites are situated in a currently dichloro-diphenyl-trichloroethane(DDT) sprayed area. A laboratory-bred reference group (AqR) were included for a histological comparison. 48% of the fish at AD were intersex individuals compared with 63% at ND, and 58% at XW. The Aq R fish had no cases of intersex. o, p0- and p, p0-DDT and metabolites dichlorodiphenyldichloroethane (DDD) and-dichlorodi-phenyl dichloro ethylene (DDE) were detected in fat samples, indicative of contamination of the aquatic environment and subsequent exposure of fish to these chemicals. Although some of the fat samples contained levels of DDTs no association could be established between intersex and chemical contaminants in fish

Testicular apoptosis in feral Clarias gariepinus using TUNEL and cleaved caspase-3 immunohistochemistry

This paper reports on the mechanistic basis of cellular death in the testis of Clarias gariepinus using the TUNEL and caspase-3 immunohistochemistry. It was also aimed to determine the testicular zone most suitable for the quantification of testicular apoptosis. The results showed that based on its immuno-expression patterns, activated caspase-3 has a clear and defined role in the progression of germ cell apoptosis in spermatogenically active catfish testis. Caspase-3 activation, and not TUNEL-detected DNA fragmentation, is associated with condensation of chromatin into a single mass. Testes of spermatogenically active catfish consist of spermatogenic, mature and spent tubules. Spermatogenic tubules were concluded to be the most suitable zone for the quantification of testicular cell death ratios as apoptotic events occurred predominantly in the secondary spermatocytes. The findings of this study will form the basis to link apoptotic events in the testes of C. gariepinus with the effects of EDC exposure in future studies.National Research Foundation of South Africa and Water Research Commission of South Afric

Organochlorine pesticide levels in Clarias gariepinus from polluted freshwater impoundments in South Africa and associated human health risks

There are increasing concerns regarding the safe human consumption of fish from polluted, freshwater impoundments. The aim of this study was to analyse the muscle tissue of the sharptooth catfish Clarias gariepinus for selected organo-chlorine pesticides (OCPs) and to perform a human health risk assessment using a standard protocol described by the United States Environmental Protection Agency (US EPA). Fish were collected from the polluted Roodeplaat-(RDPD), Rietvlei-(RVD) and Hartbeespoort (HBPD) Dam impoundments located in the north-eastern regions of South Africa. GC–MS analyses showed levels of various OCPs in fish muscle samples from all three impoundments. For fish collected from the RDPD, p,p0-DDE, endosulfan, lindane and band d-HCH were the most prevalent OCPs detected, while p,p0-DDE and endosulfan were the most predominant in fish from the RVD. Lindane and b- and d- HCH were the main OCPs detected in fish from the HBPD. Dieldrin was the only OCP detected at concentrations for which a cancer risk and a hazard index above the acceptable risk levels were estimated. This was the case for fish from both the RDPD and RVD impoundments. No toxic risk was estimated should fish from the HBPD be consumed.Water Research Commission of South Africa, the Universities of Pretoria and Johannesburg, National Research Foundation and DH Environmental Consulting.http://www.elsevier.com/locate/chemospherehb2016Urolog