Karonga Prevention Study
Introduction
Over the last 30 years the Karonga Prevention Study (KPS) has made major contributions to the understanding and control of mycobacterial and other infectious diseases. Covering the whole of Karonga District, a rural area in northern Malawi, we have a long-term and detailed understanding of demography and disease in a rural population, with a database that links our work in the district completely over time and activity. This includes data on > 300,000 identified individuals, and a continuous demographic surveillance system (DSS) in a population of 33,000 in the south of the District.
We have a long record of classical and molecular epidemiological studies, clinical trials, and work on vaccines, strengthened by our proven ability to identify people reliably and trace them and their spouses and relatives over decades, and by strong local community support and trust, built on KPS’s role in the elimination of leprosy from the district and the control of TB.
Highlights of work to date include:
- In a trial of >120,000 individuals we showed that BCG vaccine imparts considerable protection against leprosy in this population, but none against tuberculosis.
- We showed that BCG vaccination of adolescents and infants in Malawi, induced different immune responses from those induced in adolescents and infants in the UK.
- As the only long-term molecular epidemiological study of tuberculosis in an area of high HIV prevalence we have shown that recent infection is the predominant cause of TB in HIV-infected individuals, that HIV-infected cases play an important role in transmission, and that HIV may be causing a shift in M. tuberculosis genotypes.
- We have described the earliest HIV subtype C viruses known worldwide, and documented a shift from a mixed epidemic of subtypes A, D and C in the early 1980s, to the current predominance of subtype C.
- We were the first to show that antiretroviral therapy (ART) reduces mortality at the population level, with decentralisation improving the benefit for remote communities, providing strong support for the “public health” approach to ART delivery.
The KPS is run by the London School of Hygiene and Tropical Medicine (LSHTM), with increasing links with the Malawi College of Medicine. In addition to the Malawi operations, involving six international and 200 local staff, the programme includes several staff at LSHTM, and long-standing international collaborations. The project originated in 1979 as a cohort study of leprosy, funded primarily by the British Leprosy Relief Association (LEPRA). It assumed responsibility for tuberculosis diagnosis and outpatient care from 1982, and became a large WHO-supported vaccine trial in 1986, incorporating studies of HIV and skin diseases other than leprosy. The focus has shifted from leprosy to tuberculosis, HIV, demography and pneumococcal disease. Since 1996 the Wellcome Trust has been the principle funder, with additional funding from other sources, including European Union, Bill and Melinda Gates Foundation, LEPRA, Meningitis Research Foundation, ESRC (UK) and EDCTP.
