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At least 217 records · Page 12Linked to original sources

Rhipicephalus exophthalmos sp. nov., a new tick species from southern Africa, and redescription of Rhipicephalus oculatus Neumann, 1901, with which it has hitherto been confused (Acari: Ixodida: Ixodidae).

Rhipicephalus exophthalmos sp. nov., a species which has in the past been confused with Rhipicephalus oculatus Neumann, 1901, is described and illustrated from laboratory-reared specimens. Preferred hosts for the adults of this tick are various domestic and wild ungulates and hares. It is widely distributed in Namibia and in the southeastern Cape Province, South Africa, with only scattered records from elsewhere. The adults of R. oculatus are redescribed and illustrated, and the immature stages are described and illustrated for the first time. All stages feed virtually exclusively on leporids. It is common in parts of the eastern and southern Cape Province, with few records as yet from other parts of South Africa and Namibia.

Africa, Southern↗

Seroresponses to virus-like particles of human papillomavirus types 16, 18, 31, 33, and 45 in San people of Southern Africa.

Virus-like particles (VLPs) of the high-risk human papillomavirus (HPV) types 16, 18, 31, 33, and 45 were used as antigen in enzyme-linked immunosorbent assay (ELISA) to determine the prevalence of serum IgG in a group of San people originally from Namibia, now residing in South Africa. The San children had low seroprevalence to all VLP types, but 26/115 (22.6%) of the children were seropositive to at least 1 VLP type. Among the adults, seroprevalence was significantly higher. The seroprevalence of antibodies in 101 San women to VLP-16 was 16.8%, VLP-18 18.8%, VLP-31 12.9%, VLP-33 17.8%, and VLP-45 22.8%. Five of the 11 men were seropositive: 2 for VLP-31, 1 for VLP-18, 1 for VLP-33, and 1 for VLP-45. Seroreactivity appeared to be type specific, except possibly to VLP-18 and -45. Of the adults, 50.5% were seropositive to at least 1 VLP type and 24.8% were seropositive to >1 VLP type. From this study, it is concluded that the San people are exposed to HPV-16, -18, -31, -33, and -45, with antibodies to VLP-45 being the most prevalent.

Adolescent↗

Tooth size and the Carabelli trait.

The Carabelli trait and its association with maxillary molar crown base and cusp size was studied in a group of 128 Kwengo, a San-Negro hybrid community living in Western Caprivi, Namibia. The trait was classified according to a modification of the scheme put forward by Dahlberg and by Scott (In: Dental Anthropology, New York: Pergamon, 1963) (Hum. Biol. 52:63-78, 1980). Crown base areas were larger in trait-positive than in trait-negative molars, and this difference existed for all eight categories of the trait in the first molar and for most of the categories in the second and third molars. The degree of expressivity of the trait seems to be associated with molar size, but this is more apparent in the first than in the second and third molars.

Adult↗

Serum and saliva sex hormone levels in !Kung San men.

Serum concentrations of testosterone (Tser), 5 alpha-dihydrotestosterone (DHT), estradiol 17 beta (E2), and free testosterone in saliva (Tsal) were determined by means of the radioimmunoassay method in 114 !Kung San men living in the Bushmanland district of Namibia. The healthy men (mean age 26.4 years) were asked about their dietary habits over the last two months and their acute alcohol intake during the 24 hours preceding the blood and saliva sampling. Although the sex hormone status of the !Kung lies within the range of normal men reported for Caucasoid samples, both Tser and Tsal exhibit relatively low concentrations in comparison to the great majority of published mean values. On the other hand, comparatively high DHT levels point to an elevated 5 alpha-reduction of testosterone to DHT in our sample. Estradiol concentrations show no deviation from normal values reported elsewhere for healthy young men. Different dietary habits of the !Kung lead to significant differences in their sex hormone status: both levels of Tsal and the androgen ratio Tsal/Tser decrease with increasing supplement of the traditional hunter-gatherer diet with domestic and Western food products. The amount of alcohol consumed during the day before the blood and saliva sampling shows a significant effect on the DHT metabolism, and the shorter the time after drinking, the greater decrease of DHT and DHT/E2 can be observed.

Adult↗

How community action, science and common sense can work together to develop an alternative way to combat desertification.

The Spitzkoppe Community Campsite in western Namibia lies in an area with very limited water resources. Water scarcity places a constraint on community income generation and development opportunities. The existing water resources are overexploited and to ensure future water security, the community must take sustainable water management into consideration in their daily lives and business ventures, including tourism. This has been successfully achieved at the Spitzkoppe Community Campsite through a combination of high community motivation, organisation and action, the involvement of researchers and trainers in water resource management and support from developers. The most appropriate water management solutions were found through ongoing practical testing of different strategies and technologies over two years. This paper presents a case study of a community-based tourist camp at Spitzkoppe and traces the community's progress towards developing an alternative way to combat desertification and a potentially lucrative tourist business.

Camping↗

Land user participation in developing a computerised decision support system for combating desertification.

Combating desertification in natural rangelands has recently become a priority in large parts of southern Africa. Rangeland managers, farmers, scientists, conservationists and land users have been applying a variety of restoration technologies to address this problem. Bush encroachment, as part of the desertification process, involves the natural replacement of the herbaceous plant cover by undesirable problem woody species. The active and passive restoration technologies that are applied, are mainly based on indigenous knowledge and include the chemical, mechanical or manual reclamation of unproductive rangelands, as well as the combating of woody and alien species encroachment. Indigenous practices and knowledge play a major role in the effectiveness and success rate of these technologies. This project faces the challenge of bringing together both local and scientific knowledge in a single user-friendly, computerised Decision Support System (DSS) which is directly accessible by land users to support them in the process of decision making, concerning the combating of desertification. Case studies from central and northern Namibia were used to combine qualitative and quantitative data to develop this Decision Support System. The DSS currently consists of two databases and an expert system, which evaluates the results of land users' management practices, and provides easily accessible information and advice for participants in the system, based on the incorporated data. The DSS is also linked to national and international web sites and databases to offer a wider range of information on technologies concerning agricultural and conservation practices.

Community Participation↗

The South African and Namibian populations of the resurrection plant Myrothamnus flabellifolius are genetically distinct and display variation in their galloylquinic acid composition.

The polyphenol contents and compositions in desiccated leaves of Myrothamnus flabellifolius plants collected in various locations in Namibia and South Africa were analyzed using UV spectroscopy and high-performance liquid chromatography-mass spectrometry. A study of the genetic relatedness of these populations was also performed by determination of the DNA sequence of the intergenic spacer region between the psbA and the trnH genes in the chloroplast genome. Namibian M. flabellifolius plants contained significantly more polyphenols than South African plants. Namibian plants essentially contained a single polyphenol, 3,4,5-tri-O-galloylquinic acid, whereas South African plants contained a variety of galloylquinic acids including 3,4,5-tri-O-galloylquinic acid together with higher molecular weight galloylquinic acids. Sequence analysis revealed a 1.4% divergence between Namibian and South African plants corresponding to the separation of these populations of approximately 4 x 10(6) years. The significance of the poly-phenol content and composition to the desiccation tolerance of the two populations is discussed.

Base Sequence↗

Serum-IgE levels in rural Namibian infants.

Serum IgE levels were examined in 237 infants ages 2 wk to 12 mo in a remote rural area of Namibia. There was a wide range of values (0.5 to 884 IU/ml). The highest value in the first month of life was 295 IU/ml. Median values for the age groups 2 wk to 3 mo, 3 to 6 mo, and 6 to 12 mo were higher than those reported from Western countries. Values in general increased with age, but only 4% of the variation is explicable on this basis. There were differences between median values for male and female infants, but they did not reach statistical significance at the 5% level. Levels between Baster and Nama infants, the main ethnic groups in the area, did not differ. The median IgE levels in breast-fed infants, although high, tended to be lower than those in weaned infants. The differences were not statistically significant (p greater than 0.05). Investigations did not suggest that parasitic infestations or atopy were of significant importance. It was not possible to identify the factor(s) responsible for the high IgE levels. They must have been operative from very early life. However, the basic immunologic mechanisms involved are presumably genetically determined and similar to those responsible for the corresponding high IgG, IgA, and IgM levels reported in infants from developing communities.

Breast Feeding↗

Measurement of the natural radioactivity at the international high energy stereoscopic system (HESS) project in Southern Africa.

The concentrations of the natural radionuclides 40K, 238U, and 232Th in soil samples taken from the international high energy stereoscopic system (HESS) project in Namibia have been determined using an HPGe detector and found to vary from 10.8 +/- 1.4 to 26.4 +/- 1.8 Bq kg(-1) for 238U, 12.8 +/- 2.4-52.3 +/- 3.7 Bq kg(-1) for 232Th and 212.1 +/- 12.1-683.8 +/- 27.1 Bq kg(-1) for 40K. The corresponding annual effective dose equivalent is 0.06 +/- 0.01 mSv y(-1) which is less than the limit of 1 mSv y(-1) recommended for the public by the ICRP.

Africa, Southern↗

Dynamic responses of photosystem II in the Namib Desert shrub, Zygophyllum prismatocarpum, during and after foliar deposition of limestone dust.

The effects of limestone dust deposition on vegetation in desert ecosystems have not yet been reported. We investigated these effects in a succulent shrub from the Namib Desert at a limestone quarry near Skorpion Zinc mine (Namibia). Effects of limestone dust were determined in Zygophyllum prismatocarpum (dollar bush) plants with heavy, moderate and no visible foliar dust cover by means of chlorophyll a fluorescence measurements. Limestone dust deposition decreased overall plant performance through loss of chlorophyll content, inhibition of CO(2) assimilation, uncoupling of the oxygen-evolving complex and decreased electron transport. Importantly, dynamic recovery occurred after termination of limestone extraction at the quarry. Recovery was accelerated by rainfall, mainly because of dust removal from leaves and stimulation of new growth. These results indicate that limestone dust has severe effects on photosynthesis in desert shrubs, but that recovery is possible and that, in arid environments, this process is modulated by rainfall.

Air Pollution↗

Contagious bovine pleuropneumonia (CBPP) caused by vaccine strain T1/44 of Mycoplasma mycoides subsp. mycoides SC.

A study was carried out on four adult cattle to assess the pathogenicity of Mycoplasma mycoides subsp. mycoides SC strain T1/44, currently used as a vaccine for the control of contagious bovine pleuropneumonia (CBPP) in Namibia. Post mortem examination 9 weeks after endobronchial inoculation of the vaccine strain to three of the four animals revealed unilateral pleuropneumonic lesions, pleuritis and well-developed sequesters in two of the three inoculated animals and several small sequesters surrounded by pleuropneumonic lesions in the diaphragmatic and apical lobes in one animal. The fourth animal, which was not directly inoculated but was in close contact with the inoculated animals, revealed only an adhesion area of the lung to the ribcage. Serological examination carried out using the complement fixation test (CFT) detected positive titres in all three intubated animals and the indirect CBPP-LppQ-ELISA was positive for two of the three inoculated animals. The contact animal showed no seroconversion. M. mycoides subsp. mycoides SC was isolated from the sequesters of two of the inoculated animals. Isolation of mycoplasmas was not possible from the third inoculated animal due to heavy contamination of the samples by other bacteria, but the presence of M. mycoides subsp. mycoides SC could be evidenced by PCR from clinical samples. The identity of the T1/44 vaccine strain isolated from the sequesters of two animals was confirmed by T1/44-specific PCR analysis and by IS1296 typing using Southern blot. These results clearly show that inoculation of T1/44 vaccine via the endobronchial route can lead to CBPP.

Animals↗

Mitochondrial DNA analyses of the Cape hakes reveal an expanding, panmictic population for Merluccius capensis and population structuring for mature fish in Merluccius paradoxus.

The Cape hake species, Merluccius capensis and Merluccius paradoxus are the most important resource of the South African and Namibian demersal fishery, but it is unclear whether there is a single population of each shared by both countries. We analysed the population structure and evolutionary history of these two species using the variable 5' region of the mtDNA control region for 311 specimens of M. capensis and 333 specimens of M. paradoxus sampled between Lüderitz (southern Namibia) to south of Cape Point (South Africa). 107 haplotypes for M. capensis and eight haplotypes for M. paradoxus were recovered. AMOVA and pairwise Phi(st) analyses revealed no structure in M. capensis, however significant genetic differentiation between Namibian and South African 'populations' was detected for M. paradoxus. This was only restricted to mature fish older than 3 and 4 years and not for juvenile fish younger than 3 years. Analyses reveal that M. capensis has undergone population expansion (Fu's Fs=-26.65, P<0.001), possibly within the last 4500-23,000 years, whereas M. paradoxus has not. Our study highlights the utility of genetic markers to unravel the evolutionary history of sympatric species, as well as addressing management issues within regions where commercially valuable fish stocks are shared between nations.

Animals↗

The plight of modern Bushmen.

The nutritional status of 51 adult Bushmen in northeast Namibia, who have been forced to abandon their traditional hunter/gatherer lifestyle and merge with pastural/urbanized Hereros of Bantu origin, was assessed. Controls were 23 local medical staff and investigators. The diet was very unbalanced, consisting of little more than refined maize meal. Any money earned was usually spent on alcoholic beverages which, at such times, replaced normal food intake. Although short stature is thought to be genetic in origin (Bushmen were on average 15 cm shorter than Hereros), body mass corrected for height was severely diminished in 30% of adults, fat stores were depleted in 70%, and arm muscle was reduced in 75%. In general, women were more depleted than men. Blood tests showed low plasma vitamin C, folic acid, and vitamin A and E concentrations compared with controls. Plasma protein concentrations suggested a high frequency of chronic liver or enteric diseases. Examination of 44 hospital patients showed that 85% had pulmonary tuberculosis, and nutritional depletion was universal. The results raise serious doubts about the survival of Bushmen as an independent ethnic group.

Adolescent↗

The microbiology of South African traditional fermented milks.

A total of 15 samples of traditional fermented milk were collected from individual households in South Africa and Namibia. Lactic acid bacteria dominated the microflora of these samples, especially the genera Leuconostoc, Lactococcus and Lactobacillus. Other groups identified included pyogenic streptococci and enterococci. The dominant lactococci species was Lactococcus lactis subsp. lactis. Eighty-three percent of the leuconostoc isolates were identified as Leuconostoc mesenteroides subsp. dextranicum. Other species identified included Leuconostoc citreum, Leuconostoc lactis, Lactobacillus delbrueckii subsp. lactis and Lactobacillus plantarum.

Animals↗

The youngest Ediacaran fossils from southern Africa.

Discovery of fossils of the Ediacara biota near the top of the Spitzkopf Member at farm Swanpunt extends the known range of these remains in Namibia more than 600 m to near the sub-Cambrian unconformity. The fossiliferous beds occur approximately 100 m above a volcanic ash dated at 543 +/- 1 Ma, and thus may be the youngest Proterozoic Ediacara-type fossils reported anywhere in the world. Fossils are preserved within and on the tops of dm-thick beds of storm-deposited sandstone at two stratigraphic levels; the environment is interpreted as open marine, generally calm but with episodic disruptions by storm waves, and probably within the euphotic zone. The presence of Pteridinium carolinaense (St. Jean), which is also known from the classic sections in Ediacara and the White Sea among others, reinforces evidence from geochronology and chemostratigraphy that the Swartpunt section is terminal Neoproterozoic in age. The new genus and species Swartpuntia germsi is a large, multifoliate frond that exhibits at least three quilted petaloids. Macroscopically, Swartpuntia resembles Pteridinium and Ediacara-type fronds such as Charniodiscus traditionally interpreted as Cnidaria, whereas microscopically it exhibits segmentation that is remarkably similar to that of the putative worm Dickinsonia. Combination of diagnostic characters of these supposedly disparate groups in a single species suggests that many species of quilted Ediacaran organisms were more similar to each other than they were to any modern groups, and provides support for the concept of the "Vendobionta" as a late Neoproterozoic group of mainly multifoliate organisms with a distinctive quilted segmentation.

Animals↗

Serology and anthrax in humans, livestock and Etosha National Park wildlife.

Results are presented from a number of epidemiological studies using enzyme immunoassays (EIA) based on the purified anthrax toxin antigens, protective antigen, lethal factor and oedema factor. Studies on sera from a group of 62 human anthrax patients in Turkey and from cattle in Britain following two unrelated outbreaks of anthrax show that EIA using protective antigen can be a useful diagnostic aid and will detect subclinical infections in appropriate circumstances. A serological survey on wildlife in the Etosha National Park, Namibia, where anthrax is endemic, showed that naturally acquired anthrax-specific antibodies are rare in herbivores but common in carnivores; in carnivores, titres appear to reflect the prevalence of anthrax in their ranges. Problems, as yet unresolved, were encountered in studies on sera from pigs following an outbreak of anthrax on a farm in Wales. Clinical details, including treatment, of the human and one of the bovine outbreaks are summarized and discussed in relation to the serological findings.

Adolescent↗

Living with HIV: the psychological relevance of meaning making.

A qualitative study was carried out in Namibia to explore how people infected with HIV cope psychologically with this life-threatening virus. The study was based on the theoretical concept of meaning making as developed by Park and Folkman (1997; Review of General Psychology, 1, 115-44) within the framework of Lazarus' stress and coping theory (e.g., Lazarus, 1993, Psychosomatic Medicine, 55, 245-54). Ten semi-structured in-depth interviews were conducted with people who were diagnosed as HIV-positive but had not yet developed AIDS. The participants had known about their status for 6 months to 8 years. None of them received antiretroviral therapy. The interviews were analysed by means of the circular deconstruction method (Jaeggi & Faas, 1991, Arbeitsmaterialien aus dem Institut für Psychologie der Technischen Universität Berlin). The findings revealed that all participants had accepted their HIV-infection and that this acceptance enabled them to reconcile with having the virus. All participants felt largely responsible for their HIV-infection and they also felt that they had deserved the contraction of the virus. Self-blame and the experience of 'personal deservedness' (Park & Folkman, 1997) turned out to provide individuals with a sense of control over the causes of their current situation. Almost all participants reported that since being diagnosed with HIV religion became very important to them. Religious beliefs made their HIV-status more meaningful to the participants and brought a purpose to their HIV-infection as well as hope for a good outcome of this event.

Adaptation, Psychological↗

Rabies in the kudu antelope (Tragelaphus strepsiceros).

An epizootic of rabies in the greater kudu (Tragelaphus strepsiceros) occurred in Namibia during 1977-1983. The virus strain involved in the epizootic proved to be identical to rabies strains found in infected dogs in many African countries. Such a sudden and large outbreak of rabies could not be explained on the basis of the etiologic agent. A thorough investigation into kudu characteristics revealed that the kudu population had increased disproportionally before the epizootic in response to favorable conditions. The social behavior of the kudu, i.e., group browsing on acacia trees, whose thorns cause lesions in the kudu's oral cavity, as well as the excretion of relatively high titers of virus in the saliva of infected animals provide suitable conditions for transmission in the kudu population after initial infection through the jackal or other species. These factors offer an explanation for this epizootic.

Animals↗