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Biomedical subjects

O W Prozesky

Publications and source records attributed to O W Prozesky.

At least 19 recordsLinked to original sources
PubMed1992

Encephalitis and chorioretinitis associated with neurotropic African horsesickness virus infection in laboratory workers. Part I. Clinical and neurological observations.

Four laboratory workers from the same vaccine-packing facility developed at different times over an 8-year period an illness characterised by encephalitis (in 3 workers) and uveochorioretinitis (in 4). Low complement fixation titres were detected in all 4 patients to African horsesickness (AHS) virus and enzyme immunoassay and plaque reduction neutralising tests were positive, the latter against both serotypes 1 and 6. Five of 15 laboratory workers from the same facility who were healthy on clinical and ophthalmological examination showed positive plaque reduction neutralising tests but none to both serotypes 1 and 6. It is postulated that the encephalitis with the predominant temporal lobe involvement was caused by an airborne transnasal route of infection of the neurotropic AHS virus released in dried powder form, secondary to the accidental breaking of vaccine bottles. This is possibly the first report of subclinical and probable clinical neurotropic AHS infection in man.

Adolescent↗
PubMed1992

Encephalitis and chorioretinitis associated with neurotropic African horsesickness virus infection in laboratory workers. Part IV. Experimental infection of the vervet monkey (Cercopithecus pygerythrus).

Neurotropic vaccine strains of African horsesickness (AHS) virus types 1 and 6 were implicated as the possible aetiological agents in 4 cases of encephalitis and uveochorioretinitis in laboratory workers accidentally exposed to the freeze-dried vaccine preparations of the virus. To date, AHS virus has not been known to infect man. To ascertain whether or not primates were susceptible to infection with AHS virus, vervet monkeys (Cercopithecus pygerythrus) were inoculated, either transnasally or intraconjunctivally, with vaccine strains of AHS virus types 1 and 6. The course of infection was monitored using parameters such as behavioural changes, febrile reaction, cerebrospinal fluid pleocytosis, serology, magnetic resonance imaging and autopsy. Encephalitis, manifested by varying degrees of fever, behavioural changes and pleocytosis, but no chorioretinitis was detected in all 6 transnasally infected monkeys. This was confirmed by autopsy, where a meningo-encephalitis affecting the medial temporal lobe but no lesions in the eyes was demonstrated. Neither virus appeared to infect the animals after intraconjunctival inoculation. These findings support the theory that the patients were infected by the inhalation of freeze-dried vaccine preparations. The pathogenesis of the eye lesions, however, remains uncertain.

African Horse Sickness↗
PubMed1987

Rubella--a case for immunising male adolescents.

An outbreak of rubella at a training institution for predominantly adolescent males is described. The cost and inconvenience of the outbreak furnish evidence that immunisation in its own right is worth while, and should not be seen only as a means of protecting susceptible females of child-bearing age.

Adolescent↗
PubMed1987

An experimental assessment of the tampan tick Ornithodoros moubata as vector of hepatitis B virus.

Wild-caught and colonized tampan ticks, Ornithodoros moubata (Murray), were fed on hepatitis B virus (HBV)-positive blood-means in a series of four experiments. Hepatitis B surface antigen (HBsAg) persisted in nymphal and adult ticks for up to 779 days, while the epsmark antigen (HBeAg) persisted in mature nymphs up to 13 days, in adult males up to 11 days and in adult females up to 16 days. HBsAg was transmitted trans-stadially through two moults during the life cycle but transovarial transmission did not occur. The surface antigen was transmitted by two out of fifteen single ticks into 0.4 ml aliquots of HBV-negative blood, although six groups of ticks failed to transmit into 5.5 ml aliquots of blood: this antigen was not transmitted to hamsters. HBsAg was detected in samples of the ticks' coxal and rectal fluid secretions always at the infecting feed and usually at the second feed. HBeAg was only detected in one of two samples of coxal fluid collected at the infecting feed. The results as a whole indicate that no biological multiplication of virus occurs in O.moubata but that mechanical transmission from ticks to man could occur by: (i) contamination of a person when crushing infected ticks; (ii) infection by bite; (iii) contamination with coxal fluid, especially by scratching bites. This is thought to take place among the Kavango tribe in their village huts in north-eastern Namibia where infestations of infected O.moubata occur.

Animals↗
PubMed1985

Prevalence of hepatitis virus and some arbovirus infections in Kavango, northern SWA/Namibia.

A survey of the frequency of hepatitis B markers in 258 subjects from Kavango, northern South West Africa/Namibia, was undertaken during February - May 1983. The hepatitis B surface antigen and hepatitis B e antigen carrier rates were 13,6% and 2,7% respectively. Only 1,9% of the subjects were negative for all the markers tested, indicating that infection had been present at some stage in 98,1% of the sample. No known transmission method of the virus seems to fit this high exposure rate. The possibility that arthropod transmission of the virus may play a role in the epidemiology of the disease in Kavango is being investigated. All subjects tested for antibodies to hepatitis A virus were found to give a positive result. Of the arboviruses tested for, West Nile virus was usually predominant and was probably responsible for most of the arbovirus infections. Antibodies to the Sindbis, Chikungunya, Germiston and Rift Valley fever viruses were also found.

Adolescent↗
PubMed1984

Diagnosis of viral hepatitis. Experience in a South African laboratory.

Analysis of results in 14 250 specimens assayed for the diagnosis of viral hepatitis at one laboratory shows that hepatitis A and B are endemic in South Africa and that an important part of the diagnostic workload of virology laboratories now consists of determining their markers. The results fall into previously described patterns, but some anomalies were detected which indicated that unintentional parenteral transfer may occur even when testing for hepatitis B markers has been done. Furthermore, simultaneous hepatitis A and B infections or superinfection of carriers were found to be not as uncommon as one would expect. A progression flow-chart was drawn up to show how the markers change in retested patients, and this may serve as a guide for clinicians dealing with viral hepatitis in South Africa.

Clinical Laboratory Techniques↗
PubMed1983

Baseline epidemiological studies for a hepatitis B vaccine trial in Kangwane.

Hepatitis B markers were determined by radioimmunoassay of serum samples from 1 495 Black subjects representative of the resident population of Kangwane, a rural area with a high incidence of chronic liver disease and hepatocellular carcinoma. Pregnant women formed an important part of the study group, since it was intended to assess the frequency of perinatal transmission and the passive immunity of their infants, two factors which would markedly influence an infant immunization programme. A high overall marker positivity rate was found, indicating that hepatitis B is endemic. The hepatitis B surface antigen (HBsAg) carrier rate was 14,6% in adult males and 4,6% in adult females, while 82.6% of adult males and 69,4% of adult females were positive for at least one marker, indicating that infection had been present at some stage. Of infants under 1 year of age 34,5% were positive for antibodies to HBsAg (anti-HBs), compared with 9,3% at 13-24 months, which indicates that transplacental transfer of anti-HBs is frequent. Other markers were acquired even in the 1st year of life, with the sharpest increase at 3-11 years. Perinatal transmission was not common, however, and horizontal transmission during early childhood seemed to play an important role. It was concluded that the risk and frequency of infection justified a vaccine trial in this population and that the target group for vaccination should be infants under 1 year of age.

Adolescent↗
PubMed1983

Acquired immunodeficiency syndrome. A report of 2 South African cases.

This report documents the first 2 cases of the acquired immunodeficiency syndrome in male homosexuals identified in South Africa. Both patients died of Pneumocystis carinii pneumonia and both had cytomegalovirus infection. Neither had peripheral lymphadenopathy and in both cases the lymph nodes showed cortical and paracortical atrophy with marked plasma cell and histiocytic infiltration. It is suggested that this lymph node pattern represents the morphological expression of the immunological defect in this syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Immunological abnormalities in South African homosexual men.

Immunological tests of cell-mediated immunity (CMI), serological tests for antibodies to sexually transmitted and possibly immunosuppressive viruses, determination of serum immunoglobulin levels, full blood counts and serotyping for the HLA-DRw5 antigen were performed in 10 homosexual men with a mean age of 35 years (range 21-59 years). Five of these were associates of a patient who had died of confirmed acquired immunodeficiency syndrome (AIDS). At the time of investigation 9 of the men were apparently healthy and 1 had active pulmonary tuberculosis. Only in 2 subjects were no abnormalities of CMI found; they were 23 and 28 years of age and, interestingly, were also the only 2 whose sera were negative for antibodies to cytomegalovirus (CMV) and for the other viruses investigated. Of the remainder, 1 was lymphopenic, 6 had increased numbers of circulating suppressor T lymphocytes, 4 had reduced delayed-type hypersensitivity skin responses to recall antigens, and in 6 mitogen-induced lymphocyte transformation was decreased. Of these 8 subjects, 4 and 2 had antibodies to hepatitis B surface and core antigens respectively and 1 was positive for hepatitis B surface antigen and HBe antigen. The most severe abnormalities were observed in individuals who were seropositive for both CMV and hepatitis B virus. These findings indicate the existence of acquired immunosuppression in some members of the South African homosexual community. On the basis of these findings an immunological classification of potential sufferers of AIDS in the male homosexual community is proposed.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Chikungunya virus infection. A retrospective study of 107 cases.

A retrospective study of 107 cases of serologically proven chikungunya (CHIK) virus infection was undertaken. All respondents had contracted the disease at least 3 years previously; 87,9% had fully recovered, 3,7% experienced only occasional stiffness or mild discomfort, 2,8% had persistent residual joint stiffness but no pain, while 5,6% had persistent joint pain and stiffness and frequent effusions. Synovial fluid from 3 patients was analysed. All the patients with persistent joint pain and stiffness had very high antibody titres against CHIK virus.

Adolescent↗