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PubMed2005

Extreme winds and waves in the aftermath of a Neoproterozoic glaciation.

The most severe excursions in the Earth's climatic history are thought to be associated with Proterozoic glaciations. According to the 'Snowball Earth' hypothesis, the Marinoan glaciation, which ended about 635 million years ago, involved global or nearly global ice cover. At the termination of this glacial period, rapid melting of continental ice sheets must have caused a large rise in sea level. Here we show that sediments deposited during this sea level rise contain remarkable structures that we interpret as giant wave ripples. These structures occur at homologous stratigraphic levels in Australia, Brazil, Canada, Namibia and Svalbard. Our hydrodynamic analysis of these structures suggests maximum wave periods of 21 to 30 seconds, significantly longer than those typical for today's oceans. The reconstructed wave conditions could only have been generated under sustained high wind velocities exceeding 20 metres per second in fetch-unlimited ocean basins. We propose that these extraordinary wind and wave conditions were characteristic of the climatic transit, and provide observational targets for atmospheric circulation models.

Journal Article↗
PubMed2001

World pandemic of obesity: the situation in Southern African populations.

Among sub-Saharan Africans in general, a generation or so ago, there was very little gain in weight, or in blood pressure, with age. Even at present, in most populations, especially in the indigent masses, obesity prevalence remains very low, at 1-5%. However, in South Africa and some neighbouring countries, Botswana, Namibia and Zimbabwe, with rise in socio-economic status, urbanization, and diminishing physical activity, the proportion affected has increased. Rises, as noted in Cape Town, have been only slight in men, to 8%; but in women much more so, to 34%, ie to a level similar to that of African-American women. Dietarily, energy intake has increased slightly, that from fat from 15-20% to 25-30%. However, there have been falls in dietary fibre intake, to 20-25 g and 15-20 g daily, in rural and urban areas, respectively. Evidence suggests that the health disadvantage of obesity in African women is less than that in white women, and would seem to have little influence on their proneness to hypertension, coronary heart disease and breast cancer. Traditionally, and even currently, sociologically, the disorder carries little opprobrium. As to the future, the prevalence in women may well increase still further. Regarding treatment, unfortunately among African women desirous of losing weight, sustained reducing measures are near impossible; moreover, pharmacological treatment is too costly to implement.

Africa South of the Sahara↗
PubMed2001

Genetic differentiation of Glossina morsitans centralis populations.

Variation at mitochondrial and microsatellite loci was used to study the breeding and dispersal structure of Glossina morsitans centralis, in six natural populations from Botswana, the Caprivi Strip (Namibia), Zambia, and in a laboratory culture derived from Singida, Tanzania. Only seven mitochondrial haplotypes were found. Mean diversity averaged over the six natural populations was 0.216 +/- 0.085. The fixation index FST = 0.866 indicated a high degree of genetic differentiation among populations. Fifty-three alleles were detected among six microsatellite loci and six natural populations. Mean microsatellite diversity was 0.702 +/- 0.091. Depending on the estimating model used, fixation indices varied from 0.15 to 0.225 confirming that G. m. centralis populations are strongly subdivided. For all FST estimates, positive correlations were detected between pair-wise genetic distance measures and geographical distances. The difference in fixation indices estimated from mitochondrial or nuclear loci was explained by the greater sensitivity of mitochondrial genomes to genetic drift. Population differentiation can be explained by genetic drift and the subsequent recovery of extant populations from small, discontinuous populations. These data confirm genetically the collapse and retreat of G. m. centralis populations caused by the rinderpest epizootic of the late 19th and early 20th centuries.

Animals↗
PubMed2002

Population fragmentation in the southern rock agama, Agama atra: more evidence for vicariance in Southern Africa.

Mitochondrial DNA sequence data derived from two genes were used to infer phylogeographical relationships between 13 Agama atra populations. Three distinct geographical assemblages were found among the lizard populations. The first occurs in southern Namibia, the second is restricted to the western dry arid regions of South Africa, whereas the third is distributed throughout the more mesic southern and eastern parts of the subcontinent. Geographically structured differences among populations within Agama clades are probably the result of dispersal and historic isolations among populations. At the broader scale, there were marked congruences between the Agama genetic discontinuities and those described previously in other rock-dwelling vertebrates such as Pronolagus rupestris and Pachydactylus rugosus. This suggests vicariance, probably as a response to natural climatic changes during the past three million years.

Animals↗
PubMed1998

Sensitive ELISA dipstick test for the detection of chloroquine in urine under field conditions.

OBJECTIVE: To evaluate a new enzyme-linked immunosorbent assay (ELISA) dipstick test for detecting chloroquine (CQ) in urine in a malaria-endemic region of north-western Namibia. METHOD: Urine samples from 92 patients attending the outpatient department of Kamhaku Hospital with suspected malaria infection were tested for CQ with both the Dill-Glazko test and the ELISA dipstick test. Results were compared to the history of CQ intake as documented in the patients' health passes. RESULTS: The dipstick test proved an easy-to-handle and very sensitive tool for the detection of CQ with a lower limit of detection at 120 nmol/l. It showed high agreement with the history of CQ intake within the last 6 months. The specificity in a negative control group was 100%. The Dill-Glazko test was far less sensitive and specific with a lower detection limit of 150 micromol/l. CONCLUSION: The dipstick test can be used in pharmacological studies to evaluate the use of CQ, and as an inclusion criterion for in vivo and in vitro sensitivity tests, whereas the Dill-Glazko test is appropriate to test compliance during and a few days after CQ intake.

Adolescent↗
PubMed2001

Semen collection, examination and spermiogram in ostriches.

The level of fertility in the male ostrich exerts considerable influence on the efficiency of the fertilization procedure, and thus also on reproductive performance. The determination of the reproductive capacity is of particular interest with regard to the selection of single individuals for optimizing reproduction ratios. Although the breeding and raising of ostriches has become increasingly important in many countries, little research has been completed on reproductive parameters and factors that may possibly influence them. This study presents observations made concerning the quantity and quality of sperm as found in the spermatological testing of 411 ejaculate samples taken from male ostriches on two farms in Namibia. The semen volume varied between 0.1 and 1.5 ml (mean, 0.64 ml). Normal ejaculate colours ranged from white to ivory; the consistency ranged from thin creamy to viscous. The measured pH values lay between 6.4 and 8.0 (mean, 7.3). Microscopic investigations revealed sperm concentrations of 8.9-78.1 million/microl and individual sperm motility from 42 to 96% (mean, 78%). No mass motility was detectable in 42% of the ejaculates; weak mass motility was found in 46%, and clear mass movements were to be found in only 12% of samples. Regarding the morphology of the sperm, 5 to 26% were abnormal (mean, 17%) and 4 to 28% (mean, 20%) were dead. Seasonal patterns of sperm concentration and the influence of frequency of semen collection were investigated in a group of 56 healthy male ostriches. Peak sperm concentrations were found at the beginning of the breeding season in spring; the lowest values were found at the end of the breeding season in autumn. The highest quality ejaculate was obtained from those males whose semen was collected once a week. The results of this study provide fundamental data for the establishment of minimum quality requirements for ostrich sperm to be met by individuals receiving certification as breeding animals and for the selection of suitable males for use in artificial insemination.

Animals↗
PubMed2006

[Travel medicine and vaccination as a task of infection prevention--data of the special consultation hours of the public health department Frankfurt on the Main, Germany, 2002-2004].

UNLABELLED: Infection prevention is one of the main tasks of the Public Health authorities. Because of hundreds of travel associated infections imported by travellers every year and considering increasing travel activities to tropical countries, travel medicine and consultation on the correct prevention measures including vaccination is becoming more and more important. Hence the data of the special consultation hours of the public health department of Frankfurt am Main are reported and discussed with regard to possible improvements. MATERIAL AND METHODS: The public health department of Frankfurt am Main has been offering special consultation hours for travel medicine for many years. Here, data derived from the anamneses of the clients from 2002 - 2004 are reported: personal data such as age, sex, travel destination as well as medical data such as vaccination and malaria prevention. RESULTS: 2002 - 2004, more than 14,000 persons were seen in the consultation hours, more than 66% of them asked for travel health advice, about 25% of them asked for standard vaccination (such as influenza), some others asked for attestation or certification. More than 20,000 doses of vaccines were given, the most important vaccination against hepatitis A (n = 5791), hepatitis B (n = 4064), typhoid fever (n = 2718) and yellow fever (n = 2473). 2814 were informed with regard to malaria prevention, including recipes. 7814 persons with complete data on their reason for travel were subjected to more detailed analysis: 75% of them were holiday tourists, 18% travelled as "hikers", 7% were business travellers and less than 1% of them planned a round-the-world tour. The most frequent travel destinations were: Asian or African countries about 33% each, 25% Middle or South America. Thailand, South Africa with Namibia, Brazil and India were the most important countries. The time from health consultation to the beginning of the journey was too short for full vaccine protection against typhoid fever and meningococcal disease in 10% and against rabies in 44% of the consultants. There were no significant differences between holiday tourists, business and "hikers" travellers. CONCLUSION: According to many studies, only one-third of the travellers going abroad, especially to developing countries, obtain travel health information. Hence, the clients of our consultation hours are a positive selection. Nevertheless, great need for improvement could be seen as well. In many of the clients the time from getting health information and vaccination was too short for obtaining complete vaccination protection. People travelling to countries where most hepatitis A infections are obtained and re-imported home, such as Turkey and Tunisia and other Mediterranean countries almost never came for health advice and vaccination. Therefore, public health authorities should improve and increase their publicity campaigns for travel health and vaccination in order to prevent travel-associated infections and re-importation of such diseases.

Communicable Disease Control↗
PubMed1999

[Flu-like infection and liver disease after a stay in the tropics].

HISTORY AND ADMISSION FINDINGS: A 38-year-old patient, an experienced traveller to the tropics, fell ill with a flu-like infection, a fever of up to 38.6 degrees C and nausea on returning from an 8-week trip to southern Africa (Namibia, Zambia and Zimbabwe). Physical examination was unremarkable, except for slight physical debility. His father had died of liver cirrhosis of unknown aetiology, aged 68 years. INVESTIGATIONS: Laboratory tests revealed eosinophilia (12% on a count of 7,800 WBC/microliter, increased transaminase activities [SGPT 142 U/l, SGOT 50 U/l, gamma GT 32 U/l], slightly increased serum ferritin [1057 ng/dl], but normal serum iron and transferrin levels). Untreated stool contained Schistosoma mansoni eggs. Tests for a haemochromatosis gene and its type showed a homozygotic C282Y variant. Liver biopsy demonstrated chronic portal hepatitis with parenchymal transformation and marked haemosiderin deposits in liver epithelium. DIAGNOSIS, TREATMENT AND COURSE: The schistosomiasis was treated with praziquantel, 40 mg/kg by mouth on one day, divided in three doses, without complication. The haemochromatosis was treated symptomatically, at first by weekly bloodletting 500 ml while monitoring serum ferritin concentration. Life-long bloodletting at longish intervals is anticipated. CONCLUSIONS: The incidence of some infectious diseases has greatly risen as a result of an increase in tourism to distant lands. In particular, the diagnosis of frequent parasitic diseases should become part of the expertise in internal medicine. The combination of several diseases should be considered in the differential diagnosis.

Adult↗
PubMedDate not supplied

Serogenetic and haematological studies on the Kgalagadi of Botswana.

A sample of Kgalagadi, Negro speakers of a Sotho/Tswana Bantu language, inhabitants of Botswana, have been investigated for variation in 27 gene-marker systems and for haematological status and the presence of intestinal parasites. They have been found to show indications of genetic affinity both to the other Sotho/Tswana and to the Mbanderu divisions of the Herero, a Bantu-speaking Negro people of Namibia. The latter affinity appears the closer. Although the historical connection between the peoples seems unlikely on cultural and oral-historical grounds, it is not impossible, given the shallow depth of the oral history of the Herero and the consequent doubts about the antiquity of their present cultural system. Nothing in the genetic profile of the Kgalagadi contradicts the claim that they represent a very early, and perhaps the first, wave of Negro immigration into southern Africa. They have been investigated for intestinal parasites and haematological status as well. They appear to be haematologically healthy, and to possess only the narrow range of parasites previously found in the Kalahari Desert, apart from one subject in whom Hymenolepis nana (Dwarf tapeworm) was found.

Adolescent↗
PubMed2003

Origin of Hb A2' (Hb B2) [delta16(A13)Gly --> Arg (GGC --> CGC)].

On a field trip to the Dogon country (le Pays Dogon) in central Mali, we detected a high frequency of the Hb A2 abnormality, reaching higher numbers among blacksmiths (up to 12.4%) living in the same villages. In this report, by direct nucleotide sequencing and employing a polymerase chain reaction-restriction fragment length polymorphism approach, we show that the Hb A2 variant observed in the Dogon population is indeed Hb A2', also called Hb B2, and that in all of the cases the abnormal delta-globin gene is linked to a unique haplotype. The same haplotype was found linked to Hb A2' in the Herero population belonging to the South African Bantu-speaking Blacks from Namibia. Although the unique origin of this mutation in Africa is a possibility, a recurrent mutational event cannot be excluded because the linked beta cluster haplotype is one of the two major haplotypes found in all African populations. A study of populations from other regions of Africa is required to clarify this issue.

Amino Acid Substitution↗
PubMed2002

Revisiting sub-Saharan African countries' drug problems: health, social, economic costs, and drug control policy.

This article takes an international perspective on the drug problem in sub-Saharan Africa. This analysis borrows ideas from physical and economic geography as a heuristic device to conceptualize the global narcoscapes in which drug trafficking occurs. Both the legitimate and the illegal drug trade operate within the same global capitalist system and draw on the same technological innovations and business processes. Central to the paper's argument is evidence that sub-Saharan African countries are now integrated into the political economy of drug consumption due to the spill-over effect. These countries are now minor markets for "hard drugs" as the result of the activities of organizations and individual traffickers that use Africa as a staging point in their trade with Europe and the United States. As a result, sub-Saharan African countries have drug consumption problems that were essentially absent prior to 1980, along with associated health, social, and economic costs. The emerging drug problem has forced African countries to develop their own drug control policy. The sub-Saharan African countries mentioned below vary to some extent in the level of drug use and misuse problems: Burundi, Comoros, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Malawi, Mauritius, Mozambique, Reunion, Rwanda, Seychelles, Somalia, Tanzania, Uganda, Zambia, Angola, Cameroon, Central African Republic, Chad, Congo, Congo (Zaire), Equatorial Guinea, Gabon, Sao Tome and Principe, Botswana, Lesotho, Namibia, South Africa, Swaziland, Benin, Burkina Faso, Cape Verde, Cote d'Ivoire, Gambia, Ghana, Guinea, Guinea Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo. As part of this effort, African countries are assessing the health, social, and economic costs of drug-use-related problems to pinpoint methods which are both effective and inexpensive, since their budgets for social programs are severely constrained. Many have progressed to the point of adopting anti-drug laws or legislation, or of establishing a drug control agency. They are also cooperating regionally to coordinate drug control measures and working with the Organization of African Unity (OAU). In addition, almost all the sub-Saharan African countries are signatories to all United Nations drug conventions. Since the drug problem in Africa has international origins, it will take concerted international cooperation and coordinated effort to combat the "social cancer" of drugs.

Africa South of the Sahara↗
PubMedDate not supplied

Ecophysiological adaptations to dry thermal environments measured in two unrestrained Namibian scorpions, Parabuthus villosus (Buthidae) and Opisthophthalmus flavescens (Scorpionidae).

The daily changes in body temperature experienced by Parabuthus villosus (Buthidae), a scorpion found on the gravel plains around Gobabeb, Namibia, and by Opisthophthalmus flavescens (Scorpionidae), a dune-dwelling species from the same area, were measured under similar field conditions. Thermocouples implanted under the segments of the mesosoma measured maximum temperatures as high as 43 degrees C in the shade. Air temperatures reached a maximum of 33 degrees C during the daytime and a minimum of 12 degrees C at night. Very low metabolic rates compared with those of other nonsedentary invertebrates were recorded in both species; oxygen consumption ranged from 8 microL g-1 h-1 at 16 degrees C to 115 microL g-1 h-1 at 40 degrees C. A pulsed Doppler system was used to measure heart rate in situ in free-moving scorpions. At night, heart rate declined to about 4 beats min-1 in resting undisturbed scorpions. During daylight excursions and while scorpions hunted for food, heart rates as high as 180 beats min-1 were observed. Heart rate was linearly correlated with temperature in P. villosus, with a slope of 2.37 (Q10 = 2.18), but in O. flavescens only a limited correlation was observed, with a slope of 1.18 (Q10 = 1.69). In O. flavescens, heart rate showed hysteresis as body temperature rose during daylight and then decreased during the late afternoon and evening; the reverse was observed in P. villosus. In both species, haemocyanin-oxygen affinity was independent of temperature, with a higher oxygen affinity and a larger pH sensitivity in O. flavescens. The Q10's of oxygen consumption and heart rate are quite different in O. flavescens but not as different in P. villosus. Although changes in the cardiovascular system, such as stroke volume, may also play a role in meeting increased oxygen demand, the features of the haemocyanin oxygen transport system, such as the absence of temperature sensitivity and a marked pH sensitivity, can also influence the maintenance of VO2 under temperature stress. The differences in the normal thermal habitats of the two species may be used to explain the distinctions between the evolved physiological responses to temperature increase shown by the two species.

Acclimatization↗
PubMed2004

Variability of iodine content in common commercially available edible seaweeds.

Dietary seaweeds, common in Asia and in Asian restaurants, have become established as part of popular international cuisine. To understand the possibility for iodine-induced thyroid dysfunction better, we collected samples of the most common dietary seaweeds available from commercial sources in the United States, as well as harvester-provided samples from Canada, Tasmania, and Namibia. Altogether, 12 different species of seaweeds were analyzed for iodine content, and found to range from 16 microg/g (+/-2) in nori (Porphyra tenera) to over 8165 +/- 373 microg/g in one sample of processed kelp granules (a salt substitute) made from Laminaria digitata. We explored variation in preharvest conditions in a small study of two Namibian kelps (Laminaria pallida and Ecklonia maxima), and found that iodine content was lowest in sun-bleached blades (514 +/- 42 microg/g), and highest amount in freshly cut juvenile blades (6571 +/- 715 microg/g). Iodine is water-soluble in cooking and may vaporize in humid storage conditions, making average iodine content of prepared foods difficult to estimate. It is possible some Asian seaweed dishes may exceed the tolerable upper iodine intake level of 1100 microg/d.

Cooking↗
PubMed1997

Current status of polio eradication in Southern Africa.

During the 1990s, poliomyelitis transmission in 11 mainland and island nations of southern Africa appeared relatively low. However, the implementation of specific strategies recommended by the World Health Organization for eradicating polio in southern Africa began only in 1994. In 1995, oral poliovirus vaccine coverage (three doses) among infants was > or = 75% in all but 4 countries. National immunization days (NIDs) to control polio outbreaks were carried out in Namibia in 1994 and 1995. Angola, Botswana, and South Africa carried out subnational NIDs in 1995. All countries in southern Africa except Madagascar planned NIDs in 1996. Epidemiologic surveillance of acute flaccid paralysis (AFP) and laboratory surveillance of wild poliovirus was launched after nationwide training workshops in 7 mainland countries and is planned in the remaining countries by the end of 1996. Analysis of recommended performance indicators of AFP surveillance shows that substantial progress was made during 1994-1995, and the prospects for the certification of polio-free status in southern Africa on target appear good.

Adolescent↗
PubMed1997

Poliomyelitis in Angola: current status and implications for poliovirus eradication in Southern Africa.

As part of emergency assistance to the Ministry of Health (MOH), national surveillance data for poliomyelitis and charts of cases at the national rehabilitation hospital were reviewed. Poliomyelitis patients admitted to Angola's main pediatric hospital were examined. A mean of 86 cases of poliomyelitis/year were reported in Angola during 1989-1994. Review of records from non-MOH sources uncovered another 74 cases, primarily from areas outside governmental control. Hospital chart reviews revealed that 80% of the cases were children <3 years of age, mainly unvaccinated. Molecular analyses of isolates from cases in Luanda and at the Angola-Namibia border suggest that these isolates are closely related and that > or = 2 strains of wild poliovirus type 1 are circulating currently in Angola. This investigation confirms that poliomyelitis has remained endemic in Angola since independence in 1975. It affects primarily young and unvaccinated children. Control of poliomyelitis in Angola is essential to expand the polio-free zone in southern Africa.

Africa, Southern↗
PubMed1997

Plasmid analysis of Neisseria gonorrhoeae isolates and dissemination of tetM genes in southern Africa 1993-1995.

One group (145 isolates) of Neisseria gonorrhoeae was collected from municipal clinics in Bloemfontein in 1994 and a second group (65 isolates) in 1995. Penicillin and tetracycline MICs were determined and plasmid analysis performed to monitor antimicrobial susceptibilities in conjunction with the occurrence of plasmids in these isolates. The prevalence of penicillin resistance caused by beta-lactamase plasmids remained constant at 9% during the study period. Three high-level tetracycline-resistant strains (MICs 16 mg/L), the first to be detected in South Africa, were isolated in 1994. Although there was a reduction in the percentage of isolates harbouring 24.5 MDa conjugative plasmids (from 79% in 1994 to 46% in 1995), this was partially counteracted by an increase in TetM-encoding conjugative plasmids (25.2 MDa) from 2% to 18.5%. The tetM genes of 13 isolates shown to exhibit high-level tetracycline resistance were characterized as the American type. The American-type tetracycline resistance plasmid was demonstrated in 11 isolates. Digestion with Bg/l showed that two isolates harboured tetM-encoding plasmids that differed from the American- and Dutch-type plasmids described previously: one isolate contained a plasmid that produced two fragments of different sizes from those of the American-type plasmid and the second isolate possessed an American/Dutch hybrid plasmid. Auxotyping/serotyping and random amplified polymorphic DNA analysis revealed a predominant tetracycline-resistant family (NR/IA-6, genomic group I) in Bloemfontein. As there is a high incidence of chlamydial infections in southern Africa requiring tetracycline therapy, selective pressures exist in the environment for the maintenance and rapid spread of high-level tetracycline-resistant N. gonorrhoeae. It is possible that tetM genes may have emanated from Botswana and/or Namibia to Bloemfontein. The establishment of high-level tetracycline-resistant N. gonorrhoeae in Bloemfontein was seen to be complex as a related group of strains was identified, plasmid dissemination was evident and two new TetM-encoding plasmids were demonstrated. The appearance of these TetM-encoding plasmids indicates either that the American- and Dutch-type plasmids are continuing to evolve or that tetM genes are being introduced into different families of 24.5 MDa conjugative plasmids.

Cephalosporins↗
PubMed2006

High levels of genetic variation exist in Aspergillus niger populations infecting Welwitschia mirabilis hook.

Aspergillus niger is an asexual, haploid fungus which infects the seeds of Namibia's national plant, Welwitschia mirabilis, severely affecting plant viability. We used 31 randomly amplified polymorphic DNA markers to assess genetic variation among 89 A. niger isolates collected from three W. mirabilis populations in the Namib Desert. While all isolates belonged to the same vegetative compatibility group, 84% were unique genotypes, and estimates of genotypic evenness and Simpson's index of diversity approached 1.0 in the three populations. Analysis of molecular variance revealed that 78% of the total variation sampled was among isolates from individual W. mirabilis plants. Lower, but significant, amounts of variation detected among isolates from different plants (12%) and different sites (10%) also indicated some site- and plant-level genetic differentiation. Total gene diversity (H(T) = 0.264) was mostly attributable to diversity within populations (H(S) = 0.217); the relatively low level of genetic differentiation among the sites (G(ST) = 0.141) suggests that gene flow is occurring among the three distant sites. Although sexual reproduction has never been observed in this fungus, parasexuality is a well-known phenomenon in laboratory strains. We thus attribute the high levels of genetic variation to parasexuality and/or wind-facilitated gene flow from an as of yet undocumented broader host range of the fungus on other desert vegetation. Given the apparent ease of transmission, high levels of genetic diversity, and potentially broad host range, A. niger infections of W. mirabilis may be extremely difficult to control or prevent.

Aspergillus niger↗