M. J. van der Linde

Testing for clinical anaemia caused by Haemonchus spp. in goats farmed under resource-poor conditions in South Africa using an eye colour chart developed for sheep.

A novel clinical assay for the assessment and subsequent treatment of Haemonchus infection in sheep to slow down the development of anthelmintic resistance--the FAMACHA system--has been developed, tested and validated in South Africa. The system is based on a colour chart with five colour categories depicting varying degrees of anaemia that are compared with the colour of the mucous membranes of the eyes of sheep. The animal is then scored from severely anaemic (pale) through anaemic to non-anaemic (red) and those animals considered in danger of succumbing to the effects of haemonchosis are treated. This method was tested in goats farmed under resource-poor conditions in South Africa. Analyses in goats performed during the summers of 1998/1999 and 1999/2000 show a test sensitivity of 76 and 85%, respectively, meaning that the system may be used to identify correctly 76-85% of those animals in need of treatment with an anthelmintic. However, the test specificity remains low at 52-55%. This means that a large proportion of those animals that would not require treatment would in fact be treated. However, when the use of the FAMACHA system is compared with conventional dosing practices where all the animals are treated, using the FAMACHA system would result in a large proportion of the animals being left untreated. The untreated animals are then able to deposit the eggs of anthelmintic-susceptible worms on the pasture, while the treated ones should pass very few ova, given an effective anthelmintic. This maintains a reservoir of susceptible larvae in refugia, and should slow down the development of anthelmintic resistance. The validation of the FAMACHA system for goats for use by resource-poor farmers, which this paper describes, may have wide application in the tropics and subtropics of sub-Saharan Africa and elsewhere.

An evaluation of the gradsect biological survey method

Biological surveys are necessary to gather species distribution data for the identification of priority conservation areas. The rationale of the gradsect method is that sampling (transects) oriented along the steepest environmental gradient should detect the maximum number of species in an area. The efficiency of the gradsect survey method was evaluated by comparing it to random, systematic and habitat-specific survey methods, during faunal field surveys (target groups: birds and dung beetles). Three gradsects were positioned within the study area to follow the major physiographical characteristics, incorporate all environmental strata (land facets) and yet be as logistically convenient as possible. The efficiency of survey methods was expressed as the number of species recorded per sampling unit effort and illustrated using bootstrap estimations to plot species accumulation curves. The gradsect method proved to be as efficient as the habitat-specific survey method and consiste ntly more efficient than the systematic and random surveys for both taxa sampled. The present study therefore illustrates that the gradsect survey method provides a cost-effective and swift representative sample of regional fauna. Moreover, the results indicate that land-form sequences, specifically ‘land facets’, are useful surrogates when sampling environmental diversity where distinct environmental gradients such as altitude and rainfall are absent.

Incidence of Haemonchus spp. and effect on haematocrit and eye colour in goats farmed under resource-poor conditions in South Africa

The diversity and predominance of nematode genera in goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa, was determined by means of a longitudinal study of the nematode faecal egg counts (FECs) and differential third-stage nematode larvae. The animals were bled for haematocrit determination and scored for pallor of ocular mucous membranes using the FAMACHA( Copyright) method, an assay for clinical evaluation of anaemia caused by Haemonchus spp. Animals considered to be in danger of dying from anaemia caused by haemonchosis were selectively treated with an anthelmintic. Lower haematocrit values were registered during periods of heavier Haemonchus infection, which occurred from December/January to March for Rust de Winter; from December to March/April for Impendle; and from November/December to February or April for Kraaipan. There was agreement too between the lower haematocrits and paler mucous membranes scored according to the FAMACHA( Copyright) method. The use of this system may be recommended as part of an integrated approach to worm control in goats kept in the resource-poor areas studied.

The versatility of progress testing assessed in an international context: a start for benchmarking global standardization?

Sharing and collaboration relating to progress testing already takes place on a national level and allows for quality control and comparisons of the participating institutions. This study explores the possibilities of international sharing of the progress test after correction for cultural bias and translation problems. Three progress tests were reviewed and administered to 3043 Pretoria and 3001 Maastricht medical students. In total, 16% of the items were potentially biased and removed from the test items administered to the Pretoria students (9% due to translation problems; 7% due to cultural differences). Of the three clusters (basic, clinical and social sciences) the social sciences contained most bias (32%), basic sciences least (11%). The differences that were found, comparing the student results of both schools, seem a reflection of the deliberate accentuations that both curricula pursue. The results suggest that the progress test methodology provides a versatile instrument that can be used to assess medical schools across the world. Sharing of test material is a viable strategy and test outcomes are interesting and can be used in international quality control.

Intracolonial demography of the mound-building termite Macrotermes natalensis (Haviland) (Isoptera, Termitidae) in the northern Kruger National Park, South Africa

Summary: This paper reports on the number of individuals in Macrotermes natalensis (Hav.) colonies of different sized mounds in the northern Kruger National Park. Mounds were fully excavated, termites collected by means of vacuuming, and colony size estimated by sub-sampling. The proportion of termites in the mound (above and underground sections) amounts to more than 70 % of the colony; the rest being present in the surrounding soil (excavated beyond mound perimeter). It was estimated that, on average, small mounds contain more than 5000, medium mounds more than 45000, and large mounds more than 200000 individual termites. A highly significant relationship between total individuals (N) and mound height (h) was found, given by lnN = 7.893 + 1.093h (r = 0.92). Highly significant correlations (rs > 0.90) were found between and within caste numbers, and their respective ratios given. The proportion of soldiers was found to change as colonies grew larger.

Effect of nematode burden as assessed by means of faecal egg counts on body condition in goats farmed under resource-poor conditions in South Africa.

A longitudinal study was conducted of the nematode faecal egg counts (FECs) and body condition scores (BCSs) of goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa. Periods of higher FECs occurred from December/January to March/April at Rust de Winter and at Impendle and from January to March at Kraaipan. Seasonal variations in body condition were evident in the goats at Impendle with the animals showing lower BCSs from June to October. The goats at Rust de Winter and at Kraaipan did not show clear seasonal variations, although the goats at Rust de Winter showed lower BCSs from mid-July to early December. The BCSs for Rust de Winter where the animals were grazed on a private farm were generally higher than those of the other sites, where communal grazing is practised.

Modelling dimensional growth of three street tree species in the urban forest of the City of Tshwane, South Africa.

Tree height, crown height, crown diameter and stem diameter were measured for 282 trees of the indigenous species Combretum erythrophyllum, Searsia lancea and S. pendulina. Growth relationships were modelled using age as explanatory variable for stem diameter and subsequently stem diameter as explanatory variable for tree height, crown height and crown diameter. Coefficients are presented for predicting tree dimensions using a logarithmic function. There were strong correlations for stem diameter and age (r 2 ≥ 0.75), and crown diameter and stem diameter (r 2 ≥ 0.74) for all three of the species investigated. Correlations were weaker for tree height and stem diameter (r 2 ≥ 0.63), and crown height and stem diameter (r 2 ≥ 0.60) for S. pendulina but stronger for both C. erythrophyllum (r 2 ≥ 0.83) and S. lancea (r 2 ≥ 0.70) in both instances. The results can be used in forecasting the physical dimensions of these species as a function of time. The results could also be used in the process of modelling energy use reduction, air pollution uptake, rainfall interception, carbon sequestration and microclimate modification of urban forests such as those found in the City of Tshwane.

Factors affecting the career choice of first-year student teachers

ABSTRACT The lack of appropriately qualified teachers in South Africa is growing rapidly and frequency of debates about the decline in teacher numbers in South Africa is increasing. In this study, the results of an investigation into possible factors that impact on the career choice of student teachers are reported. The reasons why first-year student teachers at the University of Pretoria chose teaching as a career were studied by using a non-experimental design (survey design; administering a non-standardised questionnaire). The results revealed inter alia that a number of factors influence the career choice of first-year student teachers. Trends that emerged from the current study include the following: many more women than men enter the teaching profession; relatively few students who speak an African language choose education as a field of study and the role of parents in helping their children to choose a career cannot be underestimated.