Association of non-type b Haemophilus influenzae with HIV
Karen Cowgilla, J Anthony G Scottb
We were interested to read the article by von Gottberg et al. describing surveillance for Haemophilus influenzae infections in South Africa and the impact of H. influenzae type b (Hib) vaccine.1 The association of non-type b H. influenzae with HIV in their report was striking: 94% of isolates that were non-typable, and 100% of isolates with serotypes other than b, were from HIV-positive children.
In our own evaluation of the effectiveness of Hib vaccine in children aged < 5 years in a district in Kenya,2 we saw a similar association between non-type b H. influenzae and HIV. Among 22 children with non-type b invasive H. influenzae infections, 10 were HIV-positive, while among 54 children with invasive Hib infections, 8 were HIV-positive (OR 4.8, 95% confidence interval 1.3–17.1). The 22 non-Hib H. influenzae isolates included 9 that were of other serotypes (5 type a, 1 type c, 1 type e, and 2 type f ), 4 of which were from children with HIV, and 13 non-typable isolates, 6 of which were from children with HIV. The ORs for the association of other H. influenzae types and non-typable H. influenzae with HIV when compared to Hib were 4.6 and 4.9, respectively. It is unlikely that short-term replacement of Hib disease with non-type b H. influenzae disease was occurring in Kenya because the surveillance at our study site was consistent over the study period and we did not detect an increase in non-type b H. influenzae disease cases after vaccine introduction.
These data show that the association of non-type b H. influenzae with HIV is approximately 5 times stronger than that between Hib and HIV. As the use of Hib vaccine spreads throughout Africa and other regions where HIV prevalence is high, HIV-positive children represent a sensitive population in which to monitor for replacement disease with H. influenzae of serotypes other than type b. ■
- A von Gottberg, L de Gouveia, SA Madhi, M du Plessis, V Quan, K Soma, et al. Impact of conjugate Haemophilus influenzae type b (Hib) vaccine introduction in South Africa. Bull World Health Org 2006; 84: 811-8.
- KD Cowgill, M Ndiritu, J Nyiro, MPE Slack, S Chiphatsi, A Ismail, et al. Effectiveness of Haemophilus influenzae type b conjugate vaccine introduction into routine childhood immunization in Kenya. JAMA 2006; 296: 671-8.
- Infectious Disease Research Institute, 1124 Columbia St., Seattle, WA 98104, USA.
- Wellcome Trust/Kenya Medical Research Institute and University of Oxford.