Doctoral Degrees (Microbiology and Infection Control)

Permanent URI for this collectionhttps://hdl.handle.net/10413/7010

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Aspects of the epidemiology of malaria in Natal Province, Republic of South Africa.
(1990) Sharp, Brian Leslie.; Van den Ende, Jan.
This study investigated aspects of the epidemiology of malaria in the Natal province of the Republic of South Africa. In this study the Collins English dictionary definition of epidemiology is used where it is defined as the branch of medical science concerned with the occurrence, transmission and control of an epidemic disease. Malaria has been a notifiable disease in the Republic of South Africa since 1958. Retrospective malaria case data from the Natal province as a whole was analyzed and the data from the KwaZulu and Natal areas of the province compared. Malaria cases were reported from 35 of the 65 magisterial districts in Natal province during the study period. In the Natal areas 91.5% of the cases were reported from eight districts and in the KwaZulu areas 96.4% of the cases came from three districts or as imports from Mozambique. The overall attack rate for both the Natal and KwaZulu areas using the total population figures for each area were very similar for the period 1986-1988 at 0.71 and 0.70 per 1000 head of population for the respective areas. The disease showed a distinct seasonal pattern in the KwaZulu areas with 86.9% of the cases being classified as indigenous and only 13.1% as imported. In the Natal areas, however, the seasonal pattern was not as marked and only 12.1% of the cases were recorded as indigenous and in excess of 82% as imported. Three species of the Anopheles gambiae complex were found to occur sympatrically in Natal province, namely: An. arabiensis, An. quadriannulatus and An. merus. Of these species An. arabiensis was found to occur at five localities during or after the notification of indigenous malaria cases from these areas. Due to the sympatric distribution of these species particular emphasis was placed on species identification and in particular the biting behaviour and control of An. arabiensis was investigated. The study found both morphological and behavioural differences between populations of An. arabiensis from those areas of the province with an intra-domiciliary residual insecticide vector control programme and those from the unsprayed areas. In the unsprayed areas the majority of the indoor resting An. arabiensis had fed on man whereas in the sprayed areas the majority of the indoor resting An. arabiensis were bovine fed. In the sprayed areas, however, the majority of the An. arabiensis caught leaving huts had fed on man. The percentage survival of bloodfed An. arabiensis caught leaving huts in the DDT sprayed area was in excess of 72%. The data strongly suggest that optimal control of An. arabiensis will not be achieved using the current control strategy of the annual application of intra-domiciliary DDT.
A comparative epidemiological analysis of clinical strains of Staphylococcus aureus in Nigeria and South Africa.
(2005-09) Shittu, Adebayo Osagie.; Lin, Johnson.
Abstract available in PDF file.
The development and implementation of a mycobacterium tuberculosis rapid diagnostic assay, using reporter mycobacteriophages.
(2013) Makume, Mantha Thandiwe.; Sturm, Adriaan Willem.; Jacobs, William R.
Abstract available in PDF file.
The interaction of lymphogranuloma venereum and oculogenital chlamydia trachomatis with human keratinocytes and cervical epithelium.
(2010) Joubert, Bronwyn C.; Sturm, Adriaan Willem.
Background. Keratinocytes are the first target of infection for lymphogranuloma venereum (LGV) Chlamydia trachomatis, yet they have been omitted from pathogenesis studies. We infect keratinocytes and cervical cells with C. trachomatis and hypothesize different growth and cytotoxicity profiles among the strains. Methods. HaCaT human keratinocytes and ME-180 cervical cells were infected with C. trachomatis (multiplicity of infection (MOI) 0.025) serovars L1, L2, L3, 3 LGV clinical isolates or serovar E and incubated at 37 or 33°C for 5 days. Cytotoxicity was quantified daily using the CytoTox96® Non-Radioactive Cytotoxicity Assay, cells stained with the MicroTrak C. trachomatis Culture Confirmation kit and growth quantified by area of 100X photographs covered by Chlamydia. HaCaT and ME-180 cervical cells were infected with C. trachomatis (MOI 0.25) serovar L2 or E, incubated at 37 or 33°C for 48 hours and viewed with a transmission electron microscope (TEM). Mitochondrial activity was quantified using the MTT assay. The DeadEndTM Colorimetric TUNEL System with C. trachomatis Culture Confirmation kit as a counter-stain was used to assess cell death in infected versus uninfected cells. The BioVisionTM CaspGLOW Fluorescein Caspase Staining Kit and Transwell® Permeable Supports was used to differentiate between apoptosis mediated by cell-to-cell contact or a secreted molecule. Results. Growth in ME-180 versus HaCaT cells at 37°C was similar, but slower at 33 versus 37°C in HaCaT cells (p < 0.05). By day 5 L2 had grown faster than other strains in HaCaT cells at 37°C (p < 0.05), faster than clinical isolates in ME180 cells (p < 0.01), and faster than serovar E, and 2 clinical isolates at 33°C (p < 0.01). After 5 days L2 induced cytotoxicty was 11% in ME180 cells, which was higher than the clinical isolates (p < 0.01). In HaCaT cells at 33°C L2 EB were identified in a non-membrane state in the cytoplasm but not in the inclusion at 48 hours post infection. Serovar E but not L2 caused mitochondrial swelling at 1 h post infection in HaCaT cells at 37°C. This corresponded with a 16% reduction in mitochondrial activity (p < 0.001). TUNEL assay analyses demonstrated numerous dead cells adjacent to chlamydial inclusions for strains L2 and L3 but not L1 and E. An elevated number of caspase positive cells was detected in uninfected cell monolayers exposed to both L2 and E at 37°C but not 33°C. Conclusions. 1. C. trachomatis infects human keratinocytes in vitro. 2. Fresh clinical isolates behaved differently to the L2 reference strain. This demonstrates the need for fresh clinical isolates in pathogenesis studies of LGV. 3. In HaCaT cells at 33°C serovar L2 EB leave the intact inclusion and migrate through the cytoplasm in a non-membrane bound state 4. C. trachomatis induces apoptosis in uninfected cells exposed to infected cells via a secreted molecule at 37°C. This is more marked with serovar L2 exposure than serovar E exposure.
The RH Factor : a clinical and fundamental study of its significance in ISO- and Auto-Haemolytic anaemias.
(1973) Vos, Gerhardus Hubertus.; Villiers, T. A.; Bain, Peter G.
No abstract available.
Some aspects of liver disease in Black patients.
(1990) Maharaj, Breminand.
A study of the causes of liver enlargement amongst black patients at King Edward VIII Hospital, Durban, South Africa has revealed that congestive cardiac failure (36.7%), amoebic liver abscess (7.1%), hepatocellular carcinoma (5.8%) and cirrhosis (5.4%) are the most common causes in this population. Liver biopsy was needed to determine the cause in 28.7% of patients studied. The diagnostic yield of percutaneous liver biopsy was increased by obtaining 2 or 3 consecutive specimens for histological examination by redirecting the biopsy needle through a single entry site. This benefit was achieved without an increase in morbidity or mortality. Fatalities and complications associated with liver biopsy were more frequent at this hospital than in hospitals in Europe, The United Kingdom and North America. The complication rates after percutaneous or peritoneoscopic biopsy were 2.0% and 2.3% respectively. A total of 6 deaths was recorded. The morbidity and mortality rates were not increased when more than one specimen was taken during percutaneous biopsy. In the majority of patients in whom biopsy was carried out, after-care was either non-existent or inadequate. The "Tru-Cut" needle was used for all percutaneous liver biopsies at King Edward VIII Hospital. Two techniques, including the method recommended by the manufacturer, have been found to be incorrect; the needle must be used correctly if an adequate biopsy specimen is to be obtained for histological examination and if serious complications are to be avoided. Hepatic tuberculosis was diagnosed in 9% of patients with unexplained hepatomegaly who were subjected to liver biopsy. This disease did not yield any consistent clinical findings. In addition, liver function tests were of little diagnostic value and results of hepatic imaging techniques were often normal. Accordingly, a high index of suspicion is needed and liver biopsy is essential in patients with unexplained hepatomegaly or hepatospienomegaly, or pyrexia of unknown origin since biopsy provides the only means of diagnosing hepatic tuberculosis. The accuracy of both ultrasonography and scintigraphy in distinguishing between normal and diseased livers was low (68% and 74% respectively). These techniques performed better at detecting focal than diffuse liver disease; the sensitivity of ultrasonography and scintigraphy in focal and diffuse disease were 88% and 92%, and 27% and 54% respectively. The specificity of both procedures was high for both types of liver disease (range 91-96%). Overlap between the ultrasonographic features of amoebic liver abscess, hepatocellular carcinoma and metastatic carcinoma resulted in a correct final diagnosis being made in only 81% of patients with amoebic liver abscess, 29% with hepatocellular carcinoma and 43% of patients with metastatic carcinoma who had an ultrasound scan. Neither technique was capable of determining the cause of diffuse liver disease. Therefore, when diffuse parenchymal liver disease is suspected, liver biopsy is needed to determine the presence and nature of the disease. In addition, liver biopsy or aspiration is usually required to determine the cause of focal disease in selected patients in whom space-occupying lesions are detected on hepatic imaging studies.
A study of some aspects of senescence in embryos of zea mays L.
(1968) Berjak, Patricia.; Villiers, T. A.
Abstract available in PDF file.

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