エイズの起源

AIDSの起源は1920年代のキンシャサ*1(現在のコンゴ民主共和国*2の首都)であった。


Nuno R. Faria, Andrew Rambaut, Marc A. Suchard, Guy Baele,Trevor Bedford,Melissa J. Ward, Andrew J. Tatem, João D. Sousa, Nimalan Arinaminpathy, Jacques Pépin, David Posada, Martine Peeters, Oliver G. Pybus, Philippe Lemey “The early spread and epidemic ignition of HIV-1 in human populations” Science Vol. 346 no. 6205 pp. 56-61, 3 October 2014 http://www.sciencemag.org/content/346/6205/56


要旨に曰く、


Thirty years after the discovery of HIV-1, the early transmission, dissemination, and establishment of the virus in human populations remain unclear. Using statistical approaches applied to HIV-1 sequence data from central Africa, we show that from the 1920s Kinshasa (in what is now the Democratic Republic of Congo) was the focus of early transmission and the source of pre-1960 pandemic viruses elsewhere. Location and dating estimates were validated using the earliest HIV-1 archival sample, also from Kinshasa. The epidemic histories of HIV-1 group M and nonpandemic group O were similar until ~1960, after which group M underwent an epidemiological transition and outpaced regional population growth. Our results reconstruct the early dynamics of HIV-1 and emphasize the role of social changes and transport networks in the establishment of this virus in human populations.
これを伝えるIan Sample “HIV pandemic originated in Kinshasa in the 1920s, say scientists”*3から切り抜き;

An international team of scientists led by the universities of Oxford in Britain and Leuven in Belgium reconstructed the history of the HIV pandemic using historical records and DNA samples of the virus dating back to the late 1950s. The DNA allowed them to draw up a family tree of the virus that traced its ancestry through time and space. Using statistical models they could push farther back than the 1950s and locate the origin of the pandemic in 1920s Kinshasa.

The genetic data suggests that pandemic HIV spread rapidly through the Democratic Republic of the Congo, a country the size of western Europe. From the late 1930s to the early 1950s, the virus spread by rail and river to Mbuji-Mayi and Lubumbashi in the south and Kisangani in the north. There the virus took hold and formed secondary reservoirs from where it spread to countries in southern and eastern Africa.

From the 1920s until 1960, the pandemic HIV strain – there were others that fizzled out – spread from Kinshasa, crossed borders to other nations, and ultimately landed on distant continents. It has infected nearly 75 million people worldwide to date.

When the virus arrived, Kinshasa was bustling. It was the largest and fastest growing city in the region with transport links reaching up and down the country. The busy Congo river curved north and east to Kisangani more than 600 miles away. The railway carried scores of workers southeast to Katanga, a mining province reliant on immigrant labour, and on to Lubumbashi more than 900 miles away.

Records show that by the 1940s, more than a million people a year passed through Kinshasa on the railways alone. By 1960, the rate of new pandemic HIV infections outpaced the growth of the regional population, according to research published in Science.

While boats and trains spread the virus far, other factors played their part. Records suggest Kinshasa had a relatively high proportion of men and a consequent demand for sex workers. Some doctors may have unwittingly spread the virus further, through unsterilised jabs at sexual health clinics.

キンシャサエイズ拡散の中心地になったのは、地域の水陸の交通の要衝であったことによる。また独身男性の移動とそれに対応したセックス・ワーカーの需要。こうした条件はエイズだけでなくて、ほかの多くの感染症にも当て嵌まりそうだ。
エイズが世界的に知られるようになったのは、1980年代のアフリカ以外の諸国での流行とHIVの発見を契機にしてだったわけだが、コンゴを中心にかなりの拡大を見せていたわけだ。HIVの発見以前にエイズはどのように医学的な処理をされていたのかといえば、HIVは人の免疫システムを破壊してしまうので、端的に様々な感染症として処理されていたということになる。HIV発見以前の〈前史〉が殆ど分からなかったこともあって、エイズは様々な陰謀理論を誘発してきたけれど、今回の解明によって、陰謀理論はその主張を白紙に戻さざるを得なくなったのではないかと思うけれど、如何?
なお、エイズチンパンジーの病気から人間の病気へと転換したのは、カメルーン南部においてであるという*4
See also


James Gallagher “Aids: Origin of pandemic 'was 1920s Kinshasa'” http://www.bbc.com/news/health-29442642