Alex Welte

Short item Published on March 13, 2014

Defining optimality of a test for recent infection for HIV incidence surveillance

SACEMA has been very active in refining the use of laboratory tests for identifying recent infection (in particular of HIV) for the purpose of estimating disease incidence. We have just published a conceptual analysis of the notion of ‘test optimisation’ in a surveillance context, which should help clarify some persistent confusion that has hindered discourse in this area for years.

Published on June 12, 2013 by

Modelling – a universal practice in all of science

Welcome to a special edition of SACEMA quarterly epidemiological update – dedicated to SACEMA’s annual ‘research days’ event and other SACEMA related work. This is a glimpse into exciting trends in public health research, where mathematical methods are increasingly applied to a range of problems, to help leverage limited data, think about prospects for interventions, and formulate new hypotheses and experiments. The article also includes a reflection on modelling as a universal practice in all of science and all that differs are the kinds of models, and the techniques used to set them up and manipulate them.

Published on September 12, 2012 by


AIDS 2012 has come and gone. South African researchers and NGOs engaged in AIDS related work were ever visible, presenting new results, chairing key sessions, or delivering invited talks. Before the conference began, it was widely noted that an important shift in debate has occurred in recent years, concerning the coalescence of treatment and prevention. The real discussion is now much more about how, practically, to access the prevention benefit of treatment. This debate, at AIDS 2012, although heated at times, at least did not just go over the same old ground. Furthermore, the progress here has largely been based on the work of South Africans pushing these ideas, and amassing the evidence of early impact of our local treatment programme. It must be said that South Africans are doing some of the most important work in many aspects of HIV research, not just in applications to our specific problems, but also raising the bar internationally in the practice of good science.

Published on November 28, 2011 by

Editorial: Looking back at 2011 and into the future

The year is rushing to a close. World Aids Day is around the corner, and from our vantage point at SACEMA, 2011 is likely to be remembered as the year in which the concept of Treatment as Prevention (TasP) stopped being controversial. Few now seriously express doubt that effective ARV treatment cuts transmission, and debate has moved on to grapple with the questions of the extent, and over what time scale, this can translate into ‘game changing’ or ‘paradigm shifting’ scenarios.

Published on March 15, 2011 by

Editorial: Highlights of the CROI 2011

The Conference on Retroviruses and Opportunistic Infections (CROI) is one of the biggest events on the HIV related calendar. One of the hot topics was ‘Pre-Exposure Prophylaxis’ (PrEP). However, questions remain about how this strategy, which provides antiretroviral treatment to HIV negative people – really fits into a world in which the majority of HIV infected persons lack access to treatment. Some other highlights of CROI are also discussed. Although HIV/AIDS dominates the agenda in local epidemiology, SACEMA is not an HIV research organization, and we are pleased to present three articles on very different topics: perioperative cardiovascular disease; a methodological perspective involving carcass surveillance; and an item on how medical research can fail so impressively. We trust you will find something of interest in this edition.

Published on March 22, 2010 by

Editorial: Examining HIV incidence

The central theme of this first SACEMA Quarterly Epidemiological Update of 2010 is the rate of occurrence of new HIV infections – also known as HIV incidence. The issue is examined through three distinct perspectives: 1) Recent advances in measuring the HIV incidence in a population, and/or how it changes over time, 2) estimating the relative importance of various ‘modes of transmission’ in contributing to new cases of HIV infection, and 3) the use of antiretroviral treatment of infected individuals to curb their infectivity and hence reduce HIV incidence.

Published on June 30, 2009 by


Our second quarterly epidemiological update features a report on the 4th South African AIDS Conference and two perspectives from guest authors on the evidence on the role of Herpes infection, and on the benefits of male circumcision. These are both hotly debated and present substantial challenges in rethinking the provision of prevention measures. We had hoped to provide a report on an important international gathering related to the ‘test and treat’ proposals for HIV. However, this exciting event was postponed on short notice, due to the swine flu outbreak.

Newer Posts