N. Potgieter

Anticipating rotavirus vaccines: epidemiology and surveillance of rotavirus in South Africa

Rotavirus infection is associated with acute infantile gastroenteritis in infants and young children globally. In South Africa, rotavirus infection has been shown to be associated with approximately one-quarter of all diarrhoeal admissions to hospital. Rotavirus infection predominantly occurs in infants less than 12 months of age (75%) and has a peak of shedding during the cooler, drier months of the year. A secondary peak during the spring has been observed. Multiple infections with rotavirus and at least one other microbial agent are common. The circulating VP7 serotypes and VP4 genotypes have been determined in various regions of South Africa and show a geographic specific distribution. A decade previously, P[8]G1 or G4 strains predominated, and P[4]G2 strains occurred in an epidemic pattern in one region. More recently, rotavirus strains with P[6] genotype have become common and novel VP7/VP4 genotype combinations are occurring across the country. G9 strains have been reported from Cape Town to Vendaland. The circulating rotavirus types observed in this study add to the knowledge of the natural history of rotavirus infection and provide the groundwork to consider future vaccine strategies.

Emergence and Characterization of Serotype G9 Rotavirus Strains from Africa

Serotype G9 strains have been detected sporadically and in localized outbreaks in various African countries, including South Africa, Botswana, Malawi, Kenya, Cameroon, Nigeria, Ghana, Guinea-Bissau, Libya, and Mauritius. Serotype G9 strains were analyzed to investigate genogroup characteristics, including subgroup specificity, electropherotype, and P and G genotypes. In addition, the antigenic composition of the South African G9 strains was assessed. African G9 strains were associated with both DS-1-like characteristics and Wa-like characteristics, indicating the predisposition of G9 strains to frequently reassort. Despite these reassortment events, serotype G9 strains appear to maintain antigenic character in the outer capsid protein, as evident with the reaction of the South African G9 strains with the G9-specific monoclonal antibody F45:1. Phylogenetic analysis clustered African G9 strains geographically, regardless of genogroup characteristics, into 1 lineage (IIId). Two groups of G9 strains, originating in India and Japan, were identified in this lineage. Continuous surveillance of circulating rotavirus strains in Africa is vital to prepare for future vaccine implementation on a continent that clearly needs such preventative medicines.

Prevalence and Diversity of Rotavirus Strains in Children with Acute Diarrhea from Rural Communities in the Limpopo Province, South Africa, from 1998 to 2000

BACKGROUND Data regarding the prevalence and molecular epidemiology of rotavirus infection in rural areas of Africa are limited. In this study the prevalence and genetic diversity of rotaviruses in a rural South African setting were investigated. METHODS During June 1998 to June 2000, 420 stool specimens were collected from children with acute diarrhea who visited primary health care clinics in the rural Vhembe region, Limpopo Province, South Africa. Group A rotaviruses were detected by enzyme-linked immunosorbent assay, and the G and P types were determined by reverse-transcription polymerase chain reaction. RESULTS Of the 420 specimens, 111 (26.4%) were positive for group A rotavirus; P[6]G1 strains predominated (32.4%), followed by P[8]G1 (13.5%), P[6]G9 (4.5%), P[4]G8 (3.6%), P[4]G1 (3.6%), P[6]G8 (3.6%), and P[6]G2 (2.7%). Dual infections, with >1 P type, were seen in 33 (37.1%) of the positive specimens. CONCLUSION The unusual serotype and genotype combinations of rotavirus circulating in the rural communities of the Limpopo Province highlight the need for more studies to monitor the geographic distribution of rotavirus strains in rural African settings.

Human Norovirus prevalence in Africa: a review of studies from 1990 to 2013

To assess the contribution of Human Norovirus to diarrhoeal diseases in Africa.

Temporal Variations in Physico-Chemical and Microbiological Characteristics of Mvudi River, South Africa

Surface water has been a source of domestic water due to shortage of potable water in most rural areas. This study was carried out to evaluate the level of contamination of Mvudi River in South Africa by measuring turbidity, electrical conductivity (EC), pH, concentrations of nitrate, fluoride, chloride, and sulphate. E. coli and Enterococci were analysed using membrane filtration technique. Average pH, EC and Turbidity values were in the range of 7.2–7.7, 10.5–16.1 mS/m and 1.3–437.5 NTU, respectively. The mean concentrations of fluoride, chloride, nitrate and sulphate for both the wet and the dry seasons were 0.11 mg/L and 0.27 mg/L, 9.35 mg/L and 14.82 mg/L, 3.25 mg/L and 6.87 mg/L, 3.24 mg/L and 0.70 mg/L, respectively. E. coli and Enterococci counts for both the wet and the dry seasons were 4.81 × 103 (log = 3.68) and 5.22 × 103 (log = 3.72), 3.4 × 103 (log = 3.53) and 1.22 × 103 (log = 3.09), per 100 mL of water, respectively. The count of E. coli for both seasons did not vary significantly (p > 0.05) but Enterococci count varied significantly (p < 0.001). All the physico-chemical parameters obtained were within the recommended guidelines of the Department of Water Affairs and Forestry of South Africa and the World Health Organization for domestic and recreational water use for both seasons except turbidity and nitrates. The microbiological parameters exceeded the established guidelines. Mvudi River is contaminated with faecal organisms and should not be used for domestic purposes without proper treatment so as to mitigate the threat it poses to public health.

Fungi in housefly (Musca domestica L.) as a disease risk indicator—A case study in South Africa

Houseflies are the commonest insects which have increasingly overcrowded human dwellings, particularly in rural areas and constitute a health hazard. In the environment they move back and forth by feeding and breeding on food commodities and filth. This may lead to the spread of diseases and also mycotoxin-producing fungi. Thus frequent exposure to the activity of such houseflies will have an impact on the welfare of humans. The study investigated the natural occurrence of fungal contamination in housefly samples captured from different households and pit toilets from a rural community in South Africa. Fungal contamination data were based on the prevalence, contamination level and morphological characteristics of the different identified species. A total of 497 fungal isolates of 15 genera including Aspergillus (37%), Fusarium (17%), Penicillium (21%), Alternaria (1.4%), Chrysosporium (2%), Cladosporium (0.2%), Curvularia (0.4%), Epicoccum (1%), Eupenicillium (1%), Moniliella (9%), Mucor (2%), Nigrospora (1%), Rhizopus (2%), Scopulariopsis (2%) and Yeasts (3%) were identified from the external surfaces of both female and male houseflies. The range of fungal contamination per total fungal count isolated from female and male houseflies were recorded with mean fungal load of 4.1×10(6), 8.4×10(6), 4.4×10(6), 3.3×10(5), 9.8×10(6), 2.2×10(4), 5.6×10(4), 2.9×10(6), 5.2×10(6), 4.7×10(6), 4.5×10(7), 4.6×10(6), 2.3×10(6), 4.9×10(7) and 6.4×10(6)CFU/ml, respectively. However, the range from The most dominant fungal isolates of the female housefly samples were Aspergillus flavus, Fusarium verticillioides, Penicillium verrucosum and Moniliella suaveolens, while A. flavus, Aspergillus parasiticus, F. verticillioides, Fusarium proliferatum and Penicillium aurantiogriseum were most prevalent in male samples. The study proves that housefly is a vector for fungal spores. Therefore, it is crucial to implement housefly-control measures to curb the spread of diseases.

Detection and molecular characterisation of Giardia lamblia genotypes in Sharjah, United Arab Emirates

BACKGROUND No data are available on Giardia lamblia genotypes in the United Arab Emirates (UAE). This study aimed to identify G. lamblia from DNA extracted from human stool samples to gain information on its prevalence and to perform molecular analysis on isolates collected from expatriates from different localities residing in Sharjah, UAE. METHODS In total, 111 healthy expatriates residing in Sharjah were screened for G. lamblia using nested PCR amplification of the small subunit ribosomal RNA (ssu-rRNA) gene. Positive samples were genotyped using a nested PCR amplifying the triosephosphate isomerase (tpi) gene to differentiate between the two human assemblages (A and B). A subset of the PCR products (n=23) were sequenced and their phylogenetic relationships were determined. RESULTS Of the 111 participants, 67 (60.4%) were identified as positive for the ssu-rRNA gene. When genotyped for the tpi gene, 18.9% (21/111) were of assemblage A, 17.1% (19/111) belonged to assemblage B and 5.4% (6/111) showed patterns compatible with mixed infections. A strong correlation between the presence of diarrhoea and assemblage B was observed (χ(2)=10.553; p=0.001). Moreover, an association was also observed between mixed infections (A+B) and diarrhoea (χ(2)=8.899; p=0.003). No correlation between age, gender and geographic origin of the infected individual was noted. Phylogenetic analysis showed three clusters for the tpi gene. No relationship between the clusters and the origin of samples was noted. CONCLUSION This study is the first to determine the infection rate and genotypic composition of Giardia in Sharjah, UAE.

Inactivation of bacteria from contaminated streams in Limpopo, South Africa by silver- or copper-nanoparticle paper filters

There is an urgent need for inexpensive point-of-use methods to purify drinking water in developing countries to reduce the incidence of illnesses caused by waterborne pathogens. Previously, our work showed the deactivation of laboratory-cultured bacteria by percolation through a thick paper sheet containing either silver (Ag) or copper (Cu) nanoparticles (NP). In this study, these paper filters containing AgNPs or CuNPs have been tested with water sourced from contaminated streams in Limpopo, South Africa. Following the percolation of the contaminated stream water through the metal nanoparticle (MNP) papers, the water quality of the filtered effluent was evaluated with respect to the colony counts of total coliform and E. coli bacteria, turbidity, and either silver or copper ions. Influent total coliform bacteria concentrations from the stream water in Limpopo ranged from 250 CFU/100 mL to 1,750,000 CFU/100 mL. With the less contaminated stream water (250 - 15,000 CFU/100 mL), both AgNP and CuNP papers showed complete inactivation of the coliform bacteria. With the surface water with higher coliform bacteria levels (500,000 - 1,000,000 CFU/100 mL), both the AgNP and CuNP papers showed similar results with a slightly higher bacteria reduction of log10 5.1 for the AgNP papers than the log10 4.8 reduction for the CuNP papers. E. coli results followed similar trends. For most water purification experiments, the metal release from the sheets was minimal, with values under 0.1 ppm for Ag and 1.0 ppm for Cu (the current US EPA and WHO drinking water limits for Ag and Cu, respectively). These results show good potential for the use of paper embedded with silver and/or copper nanoparticles as effective point-of-use water purifiers.

Fungal dissemination by housefly (Musca domestica L.) and contamination of food commodities in rural areas of South Africa

Several insects that act as vectors, including houseflies (Musca domestica L.), are often considered to be an important source of fungal contamination in human foods. Houseflies are also involved in the transmission of bacterial pathogens that may pose a serious hazard to human health. Thus, the rural population of South Africa, as typified by that in the Gauteng Province investigated in this study, is at high risk from fungal exposure disseminated by houseflies and it is therefore important to assess the role of flies in contaminating various food commodities. Eighty four samples of houseflies (captured from households and pit toilets) were studied for their potential to carry fungal spores into food commodities. The fungi occurring in samples of raw maize (15) and porridge (19) were also assessed. Fungal isolates were identified based on morphological characteristics by conventional identification methods. Fifteen genera of fungi were isolated and identified, of which Aspergillus, Fusarium, Penicillium, Cladosporium, Moniliella and Mucor were the most prevalent in all three sample types analysed. The incidence rates of fungal contamination per total fungal count isolated in houseflies, maize and porridge were recorded with mean fungal load of 2×10(8) CFU/ml, 1×10(7)CFU/g and 2×10(7)CFU/g respectively. Additionally, A. flavus, A. parasiticus, F. verticillioides, F. proliferatum, P. verrucosum, P. aurantiogriseum and M. suaveolens were the most frequent fungal isolates in houseflies with incidence rate of 34%, 11%, 27%, 21%, 22%, 17% and 32% respectively. F. verticillioides, A. flavus, A. niger and P. oslonii were the most prevalent species contaminating porridge and maize with incidence rate of 23%, 32%, 16% and 28% in maize samples, while incidence rates of 59%, 15% and 29% were recorded in porridge samples with the exception of F. verticillioides. The prevalence of these genera of fungi may pose serious health risks.

Applicability of Bio-wipes for the collection of human faecal specimens for detection and characterisation of enteric viruses

To determine whether gastroenteritis viruses and other enteric viruses could be detected in faecal specimens collected with Bio‐wipes.