Medicine (RMH) - Research Publications
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ItemAfrican Australians living with HIV: a case series from Victoria(CSIRO PUBLISHING, 2010)BACKGROUND: This research aimed to describe the characteristics of African-born Victorians living with HIV, identify associations with delayed HIV diagnosis and describe their response to combination antiretroviral therapy (cART). METHODS: A case series of African-born adults living with HIV in Victoria was conducted. Data was collected in interviews and reviews of case notes. Associations with delayed HIV diagnosis (CD4 below 200 cells microL(-1) at diagnosis and/or AIDS within 3 months of HIV diagnosis) were explored using univariate regression. AIDS-defining illnesses and response to cART were described. RESULTS: Fourteen males and six females were included. Ten were born in the Horn of Africa (nine in Ethiopia). Sixteen had sexual exposure (12 heterosexual; four male-to-male sex). Seven reported acquiring HIV in Australia. Median CD4 count at diagnosis was 145 cells microL(-1). Ten had delayed HIV diagnosis, of whom eight were born in the Horn of Africa. Delayed HIV diagnosis was associated with birth in the Horn of Africa (odds ratio: 11.56). Nine had a diagnosis of AIDS, including three cases of tuberculosis, three of Pneumocystis jiroveci pneumonia and two of cerebral toxoplasmosis. Eighteen had received cART, of which 16 achieved virological suppression and 15 achieved a CD4 count above 200 cells microL(-1). Clinical failure and virological failure occurred in seven and five cases, respectively. CONCLUSIONS: HIV prevention strategies for Victoria's African communities should address HIV exposure in Australia. Ethiopian-born Victorians with HIV appear to be at particular risk of delayed diagnosis. Response to cART in this series was comparable to that observed in other industrialised countries.
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ItemEvaluation of the Antigenic Diversity of Placenta-Binding Plasmodium falciparum Variants and the Antibody Repertoire among Pregnant Women(AMER SOC MICROBIOLOGY, 2010-05)Pregnant women are infected by specific variants of Plasmodium falciparum that adhere and accumulate in the placenta. Using serological and molecular approaches, we assessed the global antigenic diversity of surface antigens expressed by placenta-binding isolates to better understand immunity to malaria in pregnancy and evolution of polymorphisms and to inform vaccine development. We found that placenta-binding isolates originating from all major regions where malaria occurs were commonly recognized by antibodies in different populations of pregnant women. There was substantial antigenic overlap and sharing of epitopes between isolates, including isolates from distant geographic locations, suggesting that there are limitations to antigenic diversity; however, differences between populations and isolates were also seen. Many women had cross-reactive antibodies and/or a broad repertoire of antibodies to different isolates. Studying VAR2CSA as the major antigen expressed by placenta-binding isolates, we identified antibody epitopes encoded by variable sequence blocks in the DBL3 domain. Analysis of global var2csa DBL3 sequences demonstrated that there was extensive sharing of variable blocks between Africa, Asia, Papua New Guinea, and Latin America, which likely contributes to the high level of antigenic overlap between different isolates. However, there was also evidence of geographic clustering of sequences and differences in VAR2CSA sequences between populations. The results indicate that there is limited antigenic diversity in placenta-binding isolates and may explain why immunity to malaria in pregnancy can be achieved after exposure during one pregnancy. Inclusion of a limited number of variants in a candidate vaccine may be sufficient for broad population coverage, but geographic considerations may also have to be included in vaccine design.
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ItemLong-Term Follow-Up of Schistosomiasis Serology Post-Treatment in Australian Travelers and Immigrants(WILEY-BLACKWELL PUBLISHING, INC, 2010)BACKGROUND: We undertook an observational follow-up study of schistosomiasis serology in both travelers and immigrants in a nonendemic country to determine the natural history of schistosomiasis antibody titer post-adequate treatment in those who have not been reexposed. METHODS: Longitudinal study of all adult travelers and immigrants presenting to the Royal Melbourne Hospital, Australia with positive schistosomiasis serology (titer >1: 64) between July 1995 and December 2005. All patients were treated with praziquantel and followed up clinically and serologically for a period up to 30 months. RESULTS: A total of 58 patients were included in the study including 26 travelers and 32 immigrants. Antibody titers often increased in the first 6 to 12 months post-treatment, especially in immigrants. After 30 months of post-treatment, 68% of travelers and 35% of immigrants (p < 0.01) achieved a fourfold antibody decline. CONCLUSIONS: Schistosomiasis antibody titers varied after adequate treatment. Therefore an increase in titer in the first 6 to 12 months or a failure to reduce after 3 years should not automatically justify re-treatment.