Search

The objective of this study was to determine the host status of commercially cultivated mango fruit, Mangifera indica L. (Anacardiaceae) to Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) in South Africa. T. leucotreta was monitored with parapheromone traps in mango orchards in Limpopo and Mpumalanga from 2007 to 2010. Fruit were inspected for the presence of T leucotreta eggs in mango orchards. Mango fruit of the cultivars 'Tommy Atkins', 'Kent', 'Keitt', and 'Sensation' were artificially infested with T. leucotreta eggs on the tree to determine if the larvae were able to develop in fruit. Mature fruit of these cultivars were harvested and were then exposed to T leucotreta eggs and the larval development monitored. Before harvest, fruit were inspected for natural infestations and a packhouse survey was conducted during the 2009-2010 season to determine if any infested fruit were present. T. leucotreta was present in all mango orchards where monitoring was done with traps but no eggs were found on the fruit, which suggests the presence of antixenosis. Development occurred in mature harvested fruit of all cultivars that had been exposed to T. leucotreta eggs. Depending on the cultivar, between 0 and 5.05% of immature fruit on the tree supported development and demonstrate antibiosis. No naturally infested fruit were found in the orchards or during the packhouse survey. Mango in South Africa is not a natural host for T. leucotreta. Mature mango fruit is an acceptable host for T. leucotreta larval development under artificial conditions. The latex plays an important role in the resistance mechanism of mango fruit to T. leucotreta.

Between July and October of 2003, 2004, and 2005, outbreaks of acute gastroenteritis occurred among children <5 years of age in Kinshasa, Democratic Republic of the Congo. Stool specimens (67 in 2003, 108 in 2004, and 116 in 2005) were collected and screened for rotaviruses using either latex agglutination (Diarlex LAA; Orion Diagnostics) or enzyme immunoassay (IDEIA; DakoCytomation). The molecular characteristics of the rotavirus strains were then determined. Group A rotavirus was detected in 195 (76%) of 258 stool specimens. Polyacrylamide gel electrophoresis was used to observe the 11 rotavirus double-stranded RNA segments in 83% of the 195 rotavirus-positive specimens. Six rotavirus group A electropherotypic patterns were noted, predominantly within the short classic pattern (111 [69%]) and the long pattern (37 [23%]). Mixed patterns were noted in the 14 remaining specimens (9%). Of the 29 samples subjected to subgrouping VP6 enzyme immunoassay, subgroup I predominated. Some of the specimens collected in 2003 (n = 26), 2004 (n = 38), and 2005 (n = 52) were analyzed by reverse-transcription polymerase chain reaction, which showed that t G8P[6] and G8P[8] strains predominated in 2003, and G1P[6] strains with short electropherotypic patterns predominated in 2004 and 2005. The emergence in Kinshasa of G8 serotypes, unusually associated with the P[6] genotype, as well as uncommon G1 rotavirus strains showing a short RNA pattern, is significant in relation to the introduction of a rotavirus vaccine and underscores the need for continued rotavirus serotype surveillance in the Democratic Republic of the Congo.

Background: A phase II, randomized, double-blind, placebo-controlled study was conducted in South Africa during 2003-2004 to evaluate the safety, reactogenicity, and immunogenicity of 2 regimens of the live attenuated oral human rotavirus vaccine RIX4414 when coadministered with the Expanded Program on Immunization childhood vaccines, including oral polio vaccine., Methods: Healthy infants were randomized (2:2:1) to receive either 2 doses of RIX4414 (n = 190; at 10 and 14 weeks, with placebo at 6 weeks), 3 doses of RIX4414 (n = 189; at 6, 10, and 14 weeks), or 3 doses of placebo (n = 96), all with concomitant routine vaccinations. The antirotavirus IgA seroconversion rate was assessed using enzyme-linked immunosorbent assay at 2 months after the last dose of RIX4414 or placebo. Antipolio types 1, 2, and 3 antibodies were measured using a virus neutralization assay. Solicited symptoms were recorded for 15 days after each dose., Results: The antirotavirus IgA seroconversion rates were similar in the RIX4414 2- and 3-dose groups (44.3% and 44.4%, respectively; P = .544, by 1-sided Fisher exact test) and antirotavirus IgA geometric mean concentrations were also comparable. Seroprotection rates for antipolio types 1, 2, and 3 antibodies were high (93%-100%) and were not significantly different among groups. Solicited symptoms reported within 15 days after vaccination were similar in all groups., Conclusions: The immune seroconversion response to the RIX4414 vaccine with 3 doses was not superior to the 2-dose regimen. There was no interference by either regimen with antibody response to oral polio vaccine, and RIX4414 was well tolerated when given with routine vaccinations.

In this study, we characterized human rotavirus strains recovered from infants and young children with acute diarrhea in Abidjan, Cote d'Ivoire, during 2000-2004. In total, 719 fecal specimens were collected from children aged 1-60 months with acute infantile gastroenteritis. Examination with a commercial enzyme-linked immunosorbent assay showed the presence of group A rotavirus antigen in 208 diarrheal specimens (28.9%). Polyacrylamide gel electrophoresis of the RNA extracted from rotavirus-positive stools yielded a variety of "long" and "short" RNA electropherotypes, which were used to help select strains for VP4 and VP7 genotyping. VP7 genotype G1 strains were circulating most commonly during the study period (53%), followed by G2 (22%) and G3 (5%) strains. Strains with multiple VP7 genotype reactivity were observed in 7.6% of specimens, and a similar number (8%) could not be typed at all. VP4 P[6] and P[8] strains circulated at similar levels (33%). Strains demonstrating multiple VP4 types were quite common (9%); however, 20% of the strains were untypeable by the methods used. Rotavirus strain diversity in Cote d'Ivoire was similar to that observed in other West African countries.

Thirty-six of 37 rotavirus strains recovered from the diarrheal stools of 166 children <3 years of age in Burkina Faso were characterized at both the antigenic and molecular levels. The rotavirus strains were confirmed by polyacrylamide gel electrophoresis; 30 displayed predominantly short electropherotype patterns, and 6 had a long RNA pattern. The strains were subgrouped by monoclonal antibody enzyme immunoassay for VP6 and were typed as subgroup I (29 of 30 short rotavirus strains) and subgroup II (5 of 6 long strains). The VP7 serotyping and genotyping showed that all 6 viruses with long electropherotype patterns were G1. The short strains were determined to be VP7 serotype G2 by reverse-transcription polymerase chain reaction (PCR) in 27 strains and nucleic acid sequencing of selected strains, although only 1 reacted with the G2-specific monoclonal antibodies. Finally, the short patterns were shown by the PCR genotyping method to be VP4 genotype P[6], and the long patterns were shown to be P[8]. The predominant strain found in Burkina Faso in this small study was an unusual G2P[6] strain that showed a short RNA electropherotype and VP6 subgroup I specificity and failed to react with a panel of G2-specific monoclonal antibodies.

Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is pest of the avocado, Persea americana (Mill.) (Lauraceae), in South Africa and is regarded as a phytosanitary threat. The objective of this study was to develop a systems approach for T. leucotreta on 'Hass' avocado that will mitigate the pest risk. T. leucotreta males were monitored with pheromone traps, and numbers declined during the winter. Field studies indicated that most of eggs were laid during January in the Deerpark area, and during harvest, only 0.029 lesions produced live larvae. Survival of larvae in fruit infested on the tree and left to develop after harvest varied and depended on the time of infestation before harvest. Fruit firmness was measured and fifth instars were only present in soft fruit. Fenpropathrin and a granulovirus were effective in reducing the infestation levels. Bags used to cover fruit also reduced infestation levels. Lesions caused by T. leucotreta were visible from two weeks after infestation and fruit with lesions can be sorted. The mean infestation rate per orchard was 0.003 lesions per fruit which makes T. leucotreta on Hass amenable to the alternative treatment efficacy approach and maximum pest limit. In the case of T. leucotreta on Hass, poor host status, production, preharvest and postharvest measures were studied and low infestation levels were observed; all these elements would make a systems approach an option. Furthermore, inspection and certification as well as shipping and distribution measures could be added.

Rotavirus infection in neonates is common and has been reported to be generally asymptomatic. In this longitudinal study, specimens were collected from 114 newborns in the Neonatal Unit at Pretoria Academic Hospital on a daily basis between January and May 1997. The babies remained in the ward between 1 week and 4 months. The stool specimens or rectal swabs were analysed for the presence of rotavirus antigen using a commercial enzyme-linked immunosorbent assay (Dako Rotavirus EIA) or electron microscopy. In total, 80 (70 per cent) of the neonates excreted rotavirus during their stay in the unit. There was a direct correlation between the length of stay in the ward and the shedding of rotavirus. The babies excreted rotavirus on average between 2 and 7 days. Rotavirus infection tended to occur within the first 2 weeks of life and was only observed once in most babies. Polyacrylamide gel electrophoresis of the RNA revealed the presence of two strains of rotavirus, with the differences in the RNA electropherotype occurring in the RNA segment triplet 7, 8 and 9. The VP7 serotype of the virus is encoded by one of these genes, and so the VP7 serotype of the virus was determined by monoclonal antibody and RT-PCR using VP7 serotype specific primers. The VP4 genotype of the viruses was also determined using RT-PCR of the VP4 gene to determine if a new rotavirus had been introduced to the ward. The strains were all characterized as G4P[6], which is similar to the antigenic make-up of the virus recovered 10 years before. This highlights the remarkable stability of rotavirus strains in neonatal units over long periods of time.

Astrovirus has been shown to be an important aetiological agent associated with gastroenteritis in children, although few studies have been conducted in Africa. In this study, stool specimens were obtained from 375 young children less than 5 years of age with acute gastroenteritis presenting at Ahmadu Bello University Hospital, and from a control group of 122 children without diarrhoeal illness. The specimens were examined for the presence of human astroviruses using a monoclonal antibody-based ELISA (Astrovirus IDEIATM, Dako, UK). Negative staining electron microscopy was performed on specimens to confirm the presence of astrovirus particles. Astrovirus was detected in 6.7 per cent (25/375) of the diarrhoeal stools compared to 5.7 per cent (7/122) of the control specimens. Astrovirus seemed to infect older children and more than half the children were between 1 and 4 years of age (15/25). Only four children were less than 6 months old. A winter peak of shedding was observed.

A survey of rotavirus infection in infants and young children with acute diarrhoea was undertaken in Zaria, northern Nigeria during 1997 and 1998. In total, 375 faecal specimens were collected from children aged between 1 and 60 months and 122 specimens from age-matched control children without diarrhoea. Fourteen specimens were collected from neonates in the University Teaching Hospital. Rotavirus antigen was detected in 61 diarrhoeal and four control specimens; four neonates were shedding rotavirus. Polyacrylamide gel electrophoresis of the viral genome showed the presence of five strains of rotavirus with long RNA electropherotypes and one short pattern. The rotavirus VP6 subgroup was determined by monoclonal antibodies specific ELISA and showed that subgroup II strains predominated (72 vs. 9.8 per cent), while eight strains could not be subgrouped and three did not react at all. Examination of the VP7 serotype showed G1 and G3 strains circulating at similar levels (29 and 25 per cent), but no serotype G2 nor G4 strains were identified. G1/G3 'mosaic' virus strains circulated commonly (10 per cent).

Ninety-two patients with SLE, 36 black and 56 white, were studied prospectively for photosensitivity and anti-Ro (SS-A) and anti-La (SS-B) antibodies. Photosensitivity was found in 19% of black patients, compared to 71% of white patients (p = 0.001). Anti-Ro antibodies were found in 69% of black and 54% of white patients (p = 0.013). Photosensitivity was present in 87% of Ro-positive white patients and in 54% of Ro-negative white patients (p = 0.007). However, in black patients with SLE there was a strong negative association: 4% of Ro-positive patients were photosensitive while 55% of Ro-negatives were photosensitive (p = 0.001). This suggests that black SLE patients may possess a factor which 'blocks' photosensitivity, perhaps by preventing local tissue damage caused by the interaction of Ro antibodies and ultraviolet light.