Stabilised antenatal HIV-l seroprevalence in Nairobi, in the face of high population mobility: is age restriction now appropriate in screening?

Abstract

Abstract

Objectives: To measure HIV -1 seroprevalence in pregnant women in Nairobi.

Design: Six serial surveys were carried out between November 1991 and April 1997. Methods: Women attending four Nairobi City Council clinics for first antenatal clinic visit answered a standard questionnaire on demographic histories and were screened for Hl'V-I. Results: Hlv-I seroprevalence rose from 12.1% at the first survey to 16.2% in the third survey, which finished in October 1993. No rise was seen in subsequent .surveys up to April 1997. Significant differences in seroprevalence was seen between women who said that their province of origin was Nyanza (22.4%), Western or Rift Valley Provinces (14.1 %), and the provinces to the east of the country (8.9%) [p<O.OOl]. Differences in Hlv-I seroprevalence between the four clinics (19.3%, 15.8%, 14.~1o and 9.3%) were highly significant [p<O.OOl]. Gross changes in the percentage of women of different provinces of origin were seen at each clinic, in different survey rounds. A linear trend in mv -1 seroprevalence with increasing age was only seen in the eastern Province of origin group.

Conclusions: The mv -1 seroprevalence has stabilised in pregnant women attending Nairobi City Council clinics. There is evidence of differential migration and mobility between population groups which have an impact on HfV -1 seroprevalence at different sites. Sentinel surveillance should be carried out on appropriate age groups and at multiple sites in large urban centres in order to maximise sensitivity of surveillance tools and obviate distortion of trends by local variations.