Does HIV infection boost carriage of Group B streptococcus bacteria in pregnant women and increase the risk of infection in new born babies?
HIV infection and GBS
Dr George Kafulafula, Dr Katherine Gray, Dr Neil French
- Start Date:
01 January 2008
Queen Elizabeth Central Hospital, Malawi-Liverpool-Wellcome Research Laboratories, College of Medicine, Blantyre, Malawi, London School of Hygiene & Tropical Medicine, London, UK
This study was designed to investigate the hypothesis that pregnant HIV-infected women carry more group B streptococcus bacteria (GBS) in their rectum and vagina than uninfected women. As carriage is a necessary pre-requisite for septicaemia and meningitis in new born babies, any increase in carriage would support the role of HIV in increasing GBS infection in this region. This would also help us understand whether specific prevention measures should be especially targeted at HIV-infected women.
The study confirmed an association between HIV and GBS carriage, although contrary to the research team’s initial expectations. It was predicted that there would be more carriage of GBS in the HIV-infected and that this would increase as women had more advanced HIV disease (assessed in this study by measuring the levels of immune cells called CD4, which drop as HIV disease progresses). However GBS carriage was actually higher in HIV-infected women with “normal” CD4 counts and fell, being lowest in women with low CD4 counts.
The results of the study support the view that HIV-infection contributes to the burden of GBS disease and that prevention, particularly by vaccination, will need to be carefully assessed in HIV-infected women. As a direct consequence of this work, the College of Medicine in Malawi has gained an international reputation in GBS research and this has led to Novartis pharmaceuticals approaching the research group to evaluate a GBS vaccine. This will proceed in January 2011 with initial studies in HIV-infected women. The vaccine is similar in construction to the successful pneumococcal vaccine (which is known to be effective in HIV-infected Malawian adults), raising the possibility of an effective and practical vaccine for GBS in the near future.