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Biomedical subjects

B D Schoub

Publications and source records attributed to B D Schoub.

At least 19 recordsLinked to original sources
PubMed1992

Estimations of the total size of the HIV and hepatitis B epidemics in South Africa.

The total number of people infected with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) in South Africa was estimated from a number of sources of seroprevalence for each of these viruses. A total figure of 122,951 HIV-infected individuals in South Africa was arrived at for January 1991; 69% (85,247) were from the urban black population and 20% (24,474) from the rural black population. The male homosexual population constituted some 7% (8,175) of the total, 94% of whom were white; however, this probably represented a substantial underestimation of the size of this population. A total of 1,475,223 carriers of HBV virus was calculated for South Africa from data obtained from 1986 to 1990. Of these, 88% (1,302,741) came from the rural black population and 8% (114,118) from the urban black population. Extrapolations from small sample numbers and often with broad assumptions are subject to considerable error. Nevertheless, estimated total figures do provide a vivid picture of the extent of these two epidemics.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Low antibody avidity in elderly chickenpox patients.

A small outbreak of chickenpox confirmed serologically in 3 elderly patients from a geriatric home is described. Disease was probably due to exogenous reinfection, yet nevertheless the avidity of specific antibodies measured by the urea denaturation test was even lower than in primary chickenpox controls, which themselves were, as expected, significantly lower than zoster controls. In elderly individuals susceptibility to reinfection with varicella-zoster virus (VZV) with clinical manifestation such as chickenpox may well be associated with the decay of specific humoral immunity detectable by antibodies of particularly low avidity, in contrast to reactivation of latent VZV presenting clinically as zoster, which is related to deficiencies in specific cellular immunity.

Aged↗
PubMed1991

Integration of hepatitis B vaccination into rural African primary health care programmes.

OBJECTIVE: To determine the efficacy of hepatitis B vaccine when added to the routine expanded programme on immunisation under field conditions in rural Africa. DESIGN: Infants were immunised according to two schedules--an early schedule at birth, 3 months, and 6 months and a later schedule to correspond with routine vaccination in the expanded programme on immunisation at 3 months, 4 1/2 months, and 6 months. SETTING: Venda, northern Transvaal, South Africa, a self governing region of 7460 square kilometers varying from rural villages to small towns. SUBJECTS: The 1989 birth cohort of Venda. MAIN OUTCOME MEASURES: Coverage for hepatitis B vaccine at first, second, and third doses; serological assessment of vaccine efficacy by prevalence of antibodies to hepatitis B surface antigen in infants who had completed the three dose course of immunisation; antibodies to hepatitis B core antigen to determine if natural infection occurred. RESULTS: Vaccine coverage for hepatitis B dropped sharply from 99% to 53% to 39% for the first, second, and third dose respectively. In contrast, vaccine coverage was maintained at 97-99% for the three doses of poliomyelitis vaccine. Serological evaluation of vaccine efficacy showed that only 3.5% of recipients of all three doses failed to develop antibodies to hepatitis B surface antigen. Only 6.6% of vaccine recipients were vaccinated according to either the early or later schedules whereas 93.4% received their doses of vaccine at intervals beyond the limits of either of the planned schedules. There was, however, no significant difference in seroconversion to the surface antigen between the "unscheduled" or scheduled groups of those who were vaccinated according to the early or late schedules. The pattern of prevalence of antibodies to hepatitis B core antigen, which showed a sharp fall in children aged over 7 months, suggested that the antibodies were acquired passively rather than by active infection. CONCLUSIONS: Supplementation of the present expanded programme on immunisation with hepatitis B vaccine in rural Africa is fraught with difficulties. However, the vaccine was effective within a fairly wide spacing of dosage. Adding hepatitis B vaccine to diphtheria, tetanus, and pertussis as a tetravalent vaccine is proposed as a means of effectively integrating it into the expanded programme on immunisation in Third World settings.

Developing Countries↗
PubMed1991

Exposure to hepatitis B virus among South African health care workers--implications for pre-immunisation screening.

Vaccination of health care workers is highly effective in preventing occupationally acquired hepatitis B virus (HBV) infection, but cost is a major factor impeding routine immunisation programmes. Pre-vaccination serological screening may be cost-beneficial if the prevalence of immunity is sufficiently high to offset its cost against the consequent reduction in vaccination needs. This critical population prevalence can be calculated given the cost of vaccination and testing. Samples of health care worker populations were examined for immunity and, using local present-day costs, it was calculated that pre-vaccination screening would be cost-beneficial in black nursing and laboratory personnel, but not their white counterparts or any student health care workers.

Cost-Benefit Analysis↗
PubMed1991

Differentiation of primary cytomegalovirus infection from reactivation using the urea denaturation test for measuring antibody avidity.

Cytomegalovirus (CMV) is probably the most common agent of prenatal infection of the newborn, and one of 20 congenitally infected newborns shows serious symptoms. It was therefore considered important to be able to differentiate primary CMV from reactivation in pregnant females. A urea denaturation test was used to distinguish primary from secondary rubella infection in which the urea is included in the wash step of the standard IgG ELISA. This resulted in the removal of low-avidity antibodies, which are the antibodies produced early in infection. A group of CMV IgM-negative and -positive sera were tested, and all but one showed moderate to high avidity, with an avidity index reading of more than 30%. Among a group of babies 3-12 months of age, who were CMV IgM positive, 55% (16 of 29) showed low-avidity CMV antibodies. A small group of renal transplant patients and patients with clinically and laboratory-confirmed CMV gave more or less predicted avidity index results. It appears that, with the method used at this laboratory, the urea denaturation test can be applied to CMV to determine primary infection or reactivation in the majority of cases.

Antibodies, Viral↗
PubMed1991

Molecular epidemiology of a coxsackievirus B3 outbreak.

An outbreak of coxsackievirus B3 infection occurred in South Africa in 1984 with a variety of clinical manifestations being observed. Fifty-one isolates from patients ranging in age from young babies to middle-aged adults were obtained. To define further the epidemiology of this outbreak all isolates were characterised by either 1- or 2-dimensional oligonucleotide mapping. One-dimensional mapping was found to be highly successful for initial screening of the isolates before further characterisation by 2-dimensional fingerprinting. All isolates were found to be essentially the same strain of coxsackievirus B3 although slight variations in both the 1- and 2-dimensional patterns could be observed. Some coxsackievirus B3 strains from geographically unrelated regions but isolated during the same time period as the outbreak showed clearly distinguishable oligonucleotide maps.

Adolescent↗
PubMed1991

Molecular epidemiology of an outbreak of poliomyelitis in South Africa in 1987/1988.

An outbreak of paralytic poliomyelitis occurred in the Republic of South Africa in 1987/88. The epidemic took place in the Natal/KwaZulu region of South Africa and was due to type 1 poliovirus. Twenty-four isolates were characterised by 1- and 2-dimensional oligonucleotide mapping and a single strain of wild-type poliovirus was identified. The same strain of virus was also isolated in other areas of South Africa at the time of the outbreak and has persisted into 1989.

Disease Outbreaks↗
PubMed1990

AIDS and tuberculosis.

The diagnostic and therapeutic implications of human immunodeficiency virus (HIV) infection and tuberculosis in South Africa, where tuberculosis remains a major health problem, are reviewed. Mycobacterium tuberculosis is a high-grade pathogen and is able to establish infection early in immunodeficiency. With HIV infection showing significant entry into the heterosexual population in the RSA, an increasing number of cases with both infections can be expected to occur. The radiological appearance in combined infection is variable, ranging from a formal cavitatory picture to the more common finding of diffuse pulmonary infiltration. Intrathoracic adenopathy is a more specific sign of tuberculosis in HIV infection, since it is not associated with persistent generalised lymphadenopathy and pulmonary opportunistic infections, such as Pneumocystis carinii pneumonia. Intercurrent pneumonic infections and other pulmonary manifestations of HIV disease render the interpretation of new infiltrates on chest radiography problematical. Tuberculin skin testing remains useful in HIV infection and should be performed in all HIV-infected patients. The value of tuberculosis serology still remains questionable. Standard antituberculosis drug regimens are effective, but maintenance treatment must be continued for life and should include isoniazid and rifampicin. BCG vaccination is recommended routinely at birth in infants with HIV infection and for asymptomatic HIV-infected individuals who have not previously been immunised.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Symptomatic rubella re-infection in early pregnancy and subsequent delivery of an infected but minimally involved infant. A case report.

A case of serologically proven symptomatic rubella re-infection in early pregnancy in a healthy multigravida who had been successfully vaccinated is reported to illustrate that the risk to the fetus is considerably less than with primary infection. The infant was infected, as evidenced by specific IgM in cord blood, but had no stigmata of congenital rubella at birth. Growth retardation was apparent at 6 months and hearing loss, not necessarily due to rubella, was detected at 8 months. Rubella re-infection, which may now be distinguished serologically by the urea degradation test from primary rubella, need not necessarily be an indication for termination of pregnancy.

Adult↗
PubMed1990

Comparison of an enzyme-immunoassay with a radio-immunoassay method for the detection of the hepatitis markers anti-HBs, anti-HBc and HBsAg.

A comparative study was carried out on a radio-immunoassay (RIA) and enzyme-immunoassay (EIA) method for detecting the hepatitis markers anti-HBs, anti-HBc and HBsAg. The results indicated that the RIA and EIA were comparable for the HBsAg marker but that the RIA test was more sensitive for anti-HBs and more specific for anti-HBc. The conclusion was that if the EIA test is used for these markers, the laboratory and clinician must be aware of these limitations.

Evaluation Studies as Topic↗