Australian encephalitis in Western Australia, 1978-1991.

OBJECTIVE: To review the various clinical manifestations of Murray Valley encephalitis (MVE) or Kunjin virus encephalitis in patients in Western Australia. DESIGN: Review of clinical records, 1978 to 1991. PATIENTS: Of 26 reported cases of Australian encephalitis, four were excluded from study because the patient's symptoms were not definitely associated with MVE virus or Kunjin virus infection. Two further cases of MVE were not reviewed as case records were not available. Of the remaining 20 patients, 18 had MVE and two had Kunjin virus encephalitis. RESULTS: Sixteen cases were in the Kimberley, a tropical region where the viruses are endemic. Four were in the subtropical Pilbara and Gascoyne regions. Thirteen of the 20 cases were in Aborigines, of whom 11 were children. The seven non-Aboriginal patients were adults. Seventeen of 20 cases were in males. The range of neurological disease and outcome was similar to that in previously reported cases, with convulsions, brainstem disease or respiratory failure in severe and fatal cases, and involvement of the spinal cord, cranial nerve or cerebellum in the moderate cases. One mild cases without neurological involvement was caused by Kunjin virus. CONCLUSIONS: The poor outcome in young Aboriginal children indicated that disease resulting from exposure early in life was more likely to be severe. The disease in adults, irrespective of facial background, was similar to that in cases reported previously from south-eastern Australia, but generally milder.

The distribution of antibodies to HHV-6 compared with other herpesviruses in young children.

Sera from 141 infants aged 0-12 months were examined for IgG antibodies to HHV-6, HSV, CMV, VZV and EBV and for HHV-6 specific IgM. Following the decline in maternal antibody, antibody to HHV-6 was found to rise by 5-6 months and approached the level found in adults by 11-12 months. In contrast the antibody rates for the other herpesviruses were much slower to rise, especially in the case of CMV and EBV. HHV-6 IgM antibodies were detected mainly in age groups showing a rapid rise in antibody to HHV-6. HHV-6-IgM was not detected in 235 cord blood samples. The data suggest that HHV-6 infection is acquired horizontally, at a very early age in Western Australia.

Frequent shedding of human herpesvirus 6 in saliva.

We have previously reported the isolation of HHV-6 from saliva samples. Because these isolations were made in PHA-stimulated lymphocytes from healthy adults, which may occasionally contain endogenous HHV-6, it was desirable to repeat this work using cord blood lymphocytes. In this study 18 isolations of viruses provisionally characterized as HHV-6 were made from 19 saliva samples by centrifugally enhanced inoculation into PHA-stimulated cord blood lymphocytes. HHV-6 was not found in 10 pernasal aspirates, 50 endocervical swabs, or 30 male urethral swabs. It is concluded that HHV-6 is usually present in the saliva of most adults and that this affords a possible explanation of the high infection rate with this virus in young children.

Population-based epidemiology of human immunodeficiency virus infection in Western Australia. Western Australian AIDS Advisory Committee.

A total of 328 cases of infection with human immunodeficiency virus (HIV) in Western Australia in 1983-1987 was studied with respect to demographic factors, the risk profile, the clinical progression of disease, the utilization of inpatient services and trends in incidence over time. The crude incidence rates were 8.8 cases/100,000 person-years in men and 0.4 cases/100,000 person-years in women. Age-specific rates peaked at 25 to 29 years of age in men. The risk of HIV infection was associated with metropolitan residence, low socioeconomic level, and two specific occupational groups. Homosexual and bisexual men constituted 86% of all cases; the incidence rate of HIV infection in such men was approximately 1000-times higher than was the incidence rate by apparent sexual transmission in heterosexual persons. However, the proportion of cases that occurred in women or that apparently was caused by heterosexual sexual transmission increased from zero in 1983-1984 to 7.5% and 5.4%, respectively, in 1987. After two years of follow-up, 71% of preclinical (category-C) patients had developed signs, symptoms or evidence of immune dysfunction, and 12% of those patients with lymphadenopathy or with other early clinical features of disease (category-B) had progressed to the acquired immunodeficiency syndrome (AIDS). At 21 months of follow-up, the survival rate with AIDS was 9%. Patients with AIDS utilized an average of 68.9 short-stay hospital bed-days per person-year, while category-B patients used 11.5 hospital bed-days per person-year. Notifications of HIV infection increased each year from 1983 to 1986, but fell by 22% in 1987. The latter may have been as a result of chance, a screening artefact or a real reduction in the incidence rate.

Efficient primary isolation of human immunodeficiency virus.

A highly-sensitive and efficient culture technique for human immunodeficiency virus type-1 (HIV-1) is described; HIV-1 was recovered from the lymphocytes of 44 (94%) antibody-seropositive healthy or symptomatic individuals. The reductions in the requirements for both the reagent volume and the number of patients' lymphocytes, together with an increased efficiency, has made this HIV-1 culture system more practical for diagnostic virology laboratories.

Centrifugal enhancement of human immunodeficiency virus (HIV) and human herpesvirus type 6 (HHV-6) infection in vitro.

The effect of centrifugal inoculation of human immunodeficiency virus (HIV) and human herpesvirus-6 (HHV-6) on the infectivity of the viruses for cell cultures was examined. Three HIV-1 strains, ARV-2, HTLV-IIIb and a local isolate, WA-46c, were tested in peripheral blood lymphocytes, HUT-78, H9 and MT-2 cells. The HHV-6 strain was a local isolate and was studied only in peripheral blood lymphocyte cultures. Centrifugal inoculation of the viruses at a force of 2500 x g for 60 min, enhanced HIV-1 infectivity by a factor of about 10-fold in all cell cultures tested. Infectivity was increased about 100-fold for HHV-6.

Human herpes virus type 6 (HHV-6) and its in vitro effect on human immunodeficiency virus (HIV).

Human herpes virus type 6 (HHV-6) was isolated from the peripheral blood lymphocytes of a patient infected with human immunodeficiency virus (HIV). Antibodies to this herpes virus were found to be widespread among adults and children in Western Australia. Co-infection studies indicated that HIV replication was inhibited by the presence of HHV-6.

Importance of virus passage history on the growth of Coxsackie B4 in human skin fibroblasts.

Human skin fibroblasts have previously been reported to display an age-dependent resistance to infection with coxsackie B4 virus. We have shown that the virus will replicate and produce CPE in human skin fibroblasts regardless of the age of the donor of the cells. The passage history of the virus was found to influence the titre of the virus in these cells.

Prenatal screening for markers of hepatitis B in aboriginal mothers resident in non-metropolitan Western Australia.

Of 1947 Aboriginal women who resided in non-metropolitan regions of Western Australia and gave birth during January 1983 to February 1985, 42% of women were screened prenatally for the presence of hepatitis B surface antigen (HBsAg). The proportions of Aboriginal women who were screened varied from 17% in the southern divisions to 72% in the Kimberley region. The screening programme identified 29 Aboriginal women with a positive result of the test. On this basis, the estimated prevalence of HBsAg among non-metropolitan Aboriginal women was 3.6% (95% confidence interval, 2.5%-5.1%). According to the geographical location of the mother's residence, the observed prevalence of HBsAg varied from 0 in the southern divisions to around 4%-5% in the central and eastern divisions.

Rapid diagnosis of cytomegalovirus infection by immunofluorescent detection of early antigen in cell culture.

The conventional culture method for the isolation of cytomegalovirus was used in parallel with the rapid method of early-antigen detection to test 485 specimens that had been collected from a total of 208 patients over a period of 11 months. Statistically, the rapid immunofluorescent method was significantly better than was the conventional test for the detection of cytomegalovirus infections. The rapid method is technically simple, sensitive and specific, and is also inexpensive when a suitable polyclonal antiserum is available. This test merits use in virology laboratories that service large hospitals.

Occurrence and distribution of hepatitis B infection in the aboriginal population of Western Australia.

In 1986, the prevalences of hepatitis B surface antigen (HBsAg), and other serological markers of infection with hepatitis B virus in the Western Australian adult Aboriginal population, were estimated using a stratified random sample of 1,150 subjects. When the estimates were standardised to the age and sex distribution of the total population of aborigines aged 12 years or over, the prevalence of HBsAg was 7% (95% confidence interval 6-9%). The prevalence of any marker, that is HBsAg and/or hepatitis surface antibody (anti-HBs), was 49% (44-54%). The follow-up blood specimens obtained from three-fifths of the antigenemic subjects indicated that 96% (88-99%) were hepatitis B carriers. Male subjects had twice the prevalence of HBsAg (10%; 7-13%) when compared with females (4%; 3-6%). However, there was only a modest elevation of the prevalence of any marker in men (53%) compared with women (46%). There was evidence that the prevalence of HBsAg increased with age, but this was not the case with any marker. Geographically, there was substantial variation in hepatitis B infection rates. The Eastern Goldfields region had the highest prevalence (HBsAg 12%; any marker 66%), followed by the Kimberley, Pilbara and Central regions (HBsAg 7-9%; any marker 56-59%). The lowest rates were evident in Perth and the South West (HBsAg 3-5%; any marker 23-25%). The highest prevalence of markers in any discrete community was observed in the desert people of Warburton (HBsAg 22%; any marker 85%). These data indicate that, according to World Health Organisation criteria, the aboriginal population of Western Australia has an intermediate to high risk of infection with hepatitis B.

Herpes simplex encephalitis in third trimester of pregnancy: successful outcome for mother and child.

A woman with herpes simplex encephalitis (HSE) in the third trimester of pregnancy is described. She was treated with acyclovir and recovered completely to deliver a normal child per vaginam at term. She had no evidence of genital or disseminated herpes virus infection. This paper illustrates that (1) the outcome of HSE in pregnancy can be favorable both for the mother and the offspring, (2) early diagnosis and use of acyclovir therapy is essential for successful outcome, and (3) the use of acyclovir in the third trimester of pregnancy was not harmful to the mother or fetus.

A modified immunofluorescence test for Epstein-Barr virus-specific IgM antibody.

The fluorescent antibody (FA) test for Epstein-Barr virus (EBV)-specific IgM antibody was improved by the use of sodium butyrate to induce a higher level of EBV antigen expression in P3HR-1 slide preparations and by removal of rheumatoid factor (RF) and IgG antibodies from test sera by means of adsorption with suspensions of Sepharose-IgG and Streptococcus pyogenes strain AR1. This method was compared with the Paul-Bunnell test (PB) on 1106 sera submitted to a routine virus diagnostic laboratory for infectious mononucleosis serology and 96.4% of sera showed concordant results. Thus the EBV-IgM-FA method was suitable for routine diagnostic use. However, it proved helpful to test EBV-IgM positive sera by PB to assist in the detection of cross-reacting IgM antibodies sometimes present.

Electron microscopy after direct ultracentrifugation.

A direct ultracentrifugation technique was used in the preparation of skin lesion specimens for examination by electron microscopy. The concentration factor of centrifuged specimens was estimated to be in excess of 1,000-fold compared to conventional adsorption techniques. This resulted in an increase of over 300% in the detection rate of herpesviruses and poxviruses from skin lesion specimens.