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Tuesday, 2 June 2009

HiV Prevalence : Circumcised Vs Uncircumcised

Interesting data on HIV prevalence in the May 2009 CSO Bulletin drawn from the ZDHS 2007 (click to enlarge).

The data appears to show that nationally, HIV prevalence rates are higher among the uncircumcised men than the circumcised men. But at the provincial level, Copperbelt and Lusaka provinces uncircumcised men have a lower prevalence rate than the circumcised men, while in the rest of the provinces, the opposite holds true. The CSO does not speculate on "why" (statisticians are generally poor on explaining things), but I speculate that there's a possible "threshold effect". Being uncircumcised is probably only useful where the HIV prevalence is lower. Simply put if many people are infected, circumcision is no protection! The call to circumcision may even be counter productive unless it was accompanied by other strategies that tackle promiscuity and unprotected sex.


  1. Cho,

    There are a lot of factors that could influence HIV statistics. Like the type of testing used.

    Is this data from a single survey, or many surveys?

    How many tests were performed (notoriously, the WHO gave the green light to use only a single, unconfirmed screening test in surveys with high prevalence levels.

    (Table A. UNAIDS and WHO recommendations for HIV testing strategies according to test objectives and prevalence of infection in the sample population - this is called "Strategy I" and is described as: Strategy I All serum/plasma is tested with one ELISA or simple/rapid assay. Serum that is reactive is considered HIV antibody positive. Serum that is non-reactive is considered HIV antibody negative)

    In other words, in high prevalence countries like Zambia, only a single, unconfirmed test is required in surveys - even thought that test is used as a screening test, because it is highly sensitive (gives a high number of false positives under normal circumstances - which is what you want if for instance testing the blood supply - better safe than sorry). However, this is problematic when testing populations which are prone to test false positive on these sensitive tests. (Like women who have been pregnant before - they regularly test false positive and need confirmation tests to establish their 'status').

    Relying only on data from antenatal clinics and a single screening tests, the UNAIDS saw alarming infection rates in Africa. When another survey type was used, the statistically representative Demographic and Health Survey, there was a massive writedown of national prevalence levels throughout Africa, but most dramatically in West Africa.

    Just by using a statistically representative survey type, Rwanda went from 11% to 3%, Sierra Leone went from 7% to 0.9%, Burkina Fasso from 6.44% to 1.8%


    How AIDS in Africa Was OverstatedReliance on Data From Urban Prenatal Clinics Skewed Early Projections
    By Craig Timberg
    Washington Post Foreign Service

    My point is: even though this survey type is statistically representative (unlike the survey type that depended on clinics catering to pregnant women only), even this survey type is based on a single screening test. By comparison, diagnosis of individual patients in the US requires 4 tests - two positive screening tests and two positive confirmation tests (named Western Blot tests).

    What would the data be, if these surveys used an actual confirmation test, instead of just one single screening test.

    Until then, it is unwise, even dangerous, to draw policy conclusions from this very flawed data. In my opinion.

  2. What the data set shows is that the relationship varies all over the place, to the point that it is SILLY to discuss amputation of exquisite sexual parts when other non-invasive preventatives are available.

    In the U.S. most of the men who have died of AIDS were circumcised at birth. Circumcision does NOT prevent AIDS.

  3. TLC Tugger,

    You make a good point, and by no means should circumcision be viewed as some sort of cure-all or prevent-all for HIV infection. That said, it is important to conform statistics to differing national circumstances, and the prevalence of HIV infection through IV drug use rather than sexual contact in the USA should be taken into account in judgments of the preventative aspects of circumcision in sexual transmission. Most American males are circumcised, and to my knowledge a larger proportion of American HIV infection is through IV drug use than any other nation, both of which affect the use of US statistics in any general infection rate vs. circumcision rate comparisons.

  4. I should perhaps add, just for the record, your best options are abstinence/marital bonds (for real now, no exceptions!), followed closely by condoms (up to 99% effective if made and used properly). Nothing else comes close.

    Intravenous (IV) drug users should be encouraged not to share needles (and ideally not reuse them without thorough sterilization), and blood donors should be routinely screened prior to transfusions where practical.

    Even with ARVs and improved testing facilities, the long gestation and infectious period of HIV makes it particularly difficult to contain by traditional quarantine. Effort has to be made on the personal level to protect oneself, and thereby others, from infection by any transmission vector of such a disease or we will never be rid of it.

    The dramatic recent reductions in mother to child transmission are very encouraging in this regard, and if we all utilize due caution and personal responsibility, then HIV/AIDS can be just a memory of the past by the time our grandchildren grow up.

    Certainly it is beautiful that now a person can, through drug therapies and much personal striving and suffering, live a productive life where just a decade ago they would most likely have been struck dead by one of a host of endemic diseases that prey upon the undefended Auto-Immune Deficiency Syndrome sufferer. BUT, this is still not preferable to a generation of Zambians hence that can grow up and pass through to adulthood without the added spectre of death or a circumscribed life due to HIV infection. Of all other deadly diseases plaguing Zambia, this is the only one that doesn't involve any other animals but humans and the virus itself, so we should be able to beat it. Let us be grateful for the former while working towards the latter.


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