Sunday, October 29, 2017

HIV and Sex: Fallacy of the Single Cause

The four Kenyan counties of Kisumu, Homa Bay, Siaya and Migori that I mentioned in my last blog post have been in the news following the rerun of the presidential elections on Thursday 26 October. Voting in these four counties was suspended at an early stage and scheduled to resume on Saturday 28, but they did not go ahead.

The result of the presidential elections held in August was disputed in court, hence the rerun. But the opposition leader, Raila Odinga, later called for the elections to be boycotted, and turnout has been very low. The four counties in question are home to the majority of Odinga’s own Luo tribe, and a large proportion of people who might vote for him as president.

Astoundingly, one third of all of Kenya’s 1.6m HIV positive people live in these four counties, even though only about one tenth of Kenyans live there. These counties make up the bulk of the former Nyanza Province, in the southeast. In the blog post before that I wrote about a contrasting area, where 0.2% of HIV positive people live: Mandera, Garissa and Wajir, the former northwestern province, with a population of about 1.6m (3.5% of Kenya’s population).

In the earlier of these two posts I speculated that HIV prevalence in the northeastern counties may have remained low because of the geographical isolation of the area. Few roads go there, infrastructure is underdeveloped, health services are few and far between, and usage of health services tends to be low. Quality of health services is also likely to be low, but less harm can result if most people stay away from facilities.

In the southwest, where infrastructure is a bit better, usage of health services is higher. This means that a lot more people are being exposed to potentially unsafe healthcare. Over 4m people live in 10,200 km2, compared to the 1.6m people in the northeast, an area of 127,300 km2. Population density can be lower than 10/km2 in the northeast and as high as 460/km2 in the southwest.

Variations in sexual behavior don’t correlate very well with variations in HIV prevalence or distribution, so it can’t be the single or simple cause of HIV transmission. UNAIDS and other establishments involved in HIV programming claim that 80-90% of HIV transmission in high prevalence African countries is due to ‘unsafe’ sexual behavior, but they have never been able to demonstrate how such a claim could be true, or even plausible.

However, it could be argued that variation in exposure to potentially unsafe healthcare practices correlates much better with HIV transmission. Both areas are isolated politically, and have been for many decades. Low usage of health facilities and social services (and low availability) seems to be a consequence of the political isolation experienced by the northwest. It is home to many of Kenya’s ethnic Somalis, a piece of land that was formerly part of Somalia.

Down in the southwest, the politically isolated Luo population experienced a certain amount of growth and prosperity after independence, especially during the explosion in the population of Nile Perch in Lake Victoria. People with a bit more money are likely to spend some of that money on healthcare. But if that healthcare is not of high quality, is not safe, this might explain why wealthier people in high prevalence African countries tend to be more likely to be infected with HIV than poorer people.

These two geographical areas have certain things in common: they are overwhelmingly populated by one ethnic group, and have both sought to distance themselves from the rest of Kenya; there has even been talk of complete political separation. But there must also be something very different about the two areas that explains why the HIV burden is over 160 times higher in the southwest than it is in the northeast.

Search for ‘sexual reductionism’ on Google and you’ll come across a discussion about a Vermeer exhibition at the New York Metropolitan Museum of Art. This will give you some idea of how current HIV epidemiology seems to proceed. Apparently the texts accompanying the paintings treat every detail of the art works as being about sex.

For UNAIDS, variation in HIV prevalence is all about sex: poor people sell sex, rich people buy sex, as do employed people, women are more vulnerable to sexual exposure than men, men are more promiscuous, sexual mores are different in Muslim communities, etc. But an alternative explanation is that variation in access to potentially unsafe healthcare facilities can better account for variation in HIV prevalence within and between geographical areas.

The history of the isolation of the southwest and northeast counties of Kenya from much of the rest of the country, political, geographical, ethnic and other forms of separation, is a long and complex one. But so too is the history of the HIV epidemic, from its origins in equatorial Africa to its global spread, and the multiple causal factors that resulted in hyperendemic levels in some countries (and within some countries), but low levels in others.

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