AEGiS-14IAC: A new approach to monitoring trends in HIV-1 prevalence, incidence and mother-to-child transmission rates in rural Africa.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

A new approach to monitoring trends in HIV-1 prevalence, incidence and mother-to-child transmission rates in rural Africa.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. MoOrC1040)

Rollins NC, Dedicoat M, Danaviah S, Page T, Bishop K, Coovadia HM, Cassol S
Africa Centre for Health and Population Studies, Mtubatuba, South Africa

BACKGROUND: Services for the prevention, treatment and care of HIV-1 infections are likely to be scaled up consequent to the renewed global commitment to controlling the AIDS pandemic. We describe a simple, robust approach for monitoring HIV-1 prevalence, incidence and mother-to-child transmission rates in rural Africa.

METHODS: Anonymous unlinked dried blood spot samples (DBS) were obtained from mothers and their infants attending immunization clinics. Mothers were advised that samples would be tested for HIV and identified only with a barcode number. Antibody testing of maternal DBS was performed using a broad based HIV-1/HIV-2 ELISA and a second confirmatory GAC ELISA. In a subset of mothers, ELISA positives were confirmed using the NucliSens HIV-1 RNA qualitative test. ELISA negatives were tested for viral RNA to identify acute incident infections. Infant samples were tested for maternal antibodies and HIV RNA using the same assays.

RESULTS: Blood spots from 988 mothers and 742 infants attending six rural immunization clinics between May and September 2000 were analysed. The overall maternal seroprevalence was 30.2%. RNA testing of seronegative mothers identified an additional 8 (1.28%) women with newly-acquired incident infection. Assuming the mean duration of RNA viraemia prior to seroconversion is between 28-42 days, this translates into an estimated annual incidence of between 16.6% or 11.1% respectively. Of 267 infants with positive ELISA for maternal antibody i.e. infected mother, a total of 55 infections (20.6%) were identified by RNA PCR. HIV-1 vertical transmission rates increased from 12.0% in infants <6 weeks of age to 31.7% at 1.5-3.0 months.

CONCLUSIONS: This approach provides a reliable and effective tool for assessing operational programmes, even in remote country settings. The principle of this approach can be utilised to monitor changing trends in the HIV epidemic and to assess the impact of interventions.

Keywords: AEGIS, Incidence, Prevalence, HIV-1, HIV Infections, HIV-2, Disease Transmission, Vertical, HIV Seropositivity, Mothers, Acquired Immunodeficiency Syndrome, RNA, Viral, Enzyme-Linked Immunosorbent Assay, Polymerase Chain Reaction, Disease Outbreaks, Seroepidemiologic Studies, Africa, Child, Infant, Human, Female, transmission, epidemiology, trends

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MoOrC1040