マラリア対策の難しさ

今週のNatureはマラリア対策の現状を伝える現地取材のリポート記事Malaria’s ticking time bombがありました。Nature自身がレポーターを派遣したこともあり社説でも取り上げています。特集を読む前に社説を読んでおくと取り上げているトピックの概要は問題点をまず把握できるのでオススメです。

EDITORIAL  25 JULY 2018

Pay people to fight malariaWorkers on the front line of the battle against the disease are too often overlooked as scientists and funders plot how to defeat malaria.

Nature sent a reporter to Myanmar, Cambodia and Thailand in May to see how researchers are helping countries in the Greater Mekong region reach their goal of eliminating malaria by 2030. Her News Feature this week highlights how political, financial and geographical obstacles allow the disease to persist. The broader malaria community, including researchers and funders, must do more to address these challenges. It is a race against time. The disease must be stamped out in the region now, while it remains relatively rare. Allow it to increase, and the chance will be lost. Worse, drug-resistant parasites there will multiply and spread.

It’s no secret that the best way to beat malaria is to ensure that every infected person can quickly reach a health worker and be given artemisinin-based combination therapies (ACTs) — pills that swiftly kill the parasites that cause malaria before they spread to other people. The importance of health workers is highlighted by what happens in their absence. Hundreds of thousands of African children die every year because they do not get the pills in time. And in Venezuela — once declared malaria-free — the disease has come back with a vengeance as political instability has fractured health services.

どうして特集記事のタイトルMalaria’s ticking time bomb（マラリアの時限爆弾）のようになるのかも、社説の第一パラグラフで述べられています。It is a race against time.（それは時間との戦いだ）以降の部分です。メコン地域はマラリアにかかった世界人口の７%ほどにすぎないのですが、特効薬の耐性ができた蚊が生まれており、放置しておくとこの蚊が世界中に広がってしまうという危機感があるようです。

マラリア撲滅と言うのは簡単ですが、実施するのは大変なようで、その難しさが特集記事のメインを占めています。社説でもこの問題点をあげてくれています。ゲイツ財団がマラリア撲滅に取り組んでいることはこのブログでも何回か取り上げていますが、最前線で従事している医療関係者の給料を負担していることはないそうです。

Yet health systems in many malaria-endemic nations are riddled with holes. Malaria health workers are often unsalaried, so many leave for other jobs. Networks of researchers, technicians and administrators support health workers, provide surveillance and inform policy. But health budgets in low-income nations are often too small to attract enough of these skilled workers.

At present, too many of these crucial positions are unpaid. The Bill & Melinda Gates Foundation in Seattle, Washington, the US government and many other donors do not pay salaries for health workers and other staff in national health systems. The Global Fund to Fight AIDS, Tuberculosis and Malaria is a rare exception in supplementing pay for national health workers — but even it does not allocate funds to researchers and officials at higher levels in ministries of health. It says that national governments should do this, but many can’t or don’t.

特集記事は3000語程度の長文記事です。リポート記事にありがちなエピソードから書き出しているので、イメージがつかなかったら概要を説明してくれている第３パラグラフから読んだ方が事情をつかめます。

Malaria’s ticking time bomb

Scientists are racing to stamp out the disease in southeast Asia before unstoppable strains spread.

By Amy Maxmen

Photography by Adam Dean for Nature

What happens next here matters for the entire world; malaria remains one of the biggest killers in low-income countries. Estimates of the number of deaths each year range from 450,000 to 720,000 — and ACT pills keep that toll from being much higher. And although southeast Asia accounts for just 7% of malaria cases worldwide, it has a notorious history as the breeding ground for strains of malaria parasites that resist every drug thrown at them and then spread to other regions.

In 2015, reports of drug resistance prompted the governments of five countries in the Greater Mekong Subregion — Cambodia, Thailand, Vietnam, Laos and Myanmar — to pledge to banish P. falciparum from the region by 2025. Together with the World Health Organization (WHO), the countries drew up plans and budgets. This year, the nations’ governments have committed US$41 million towards the effort; the Global Fund to Fight AIDS, Tuberculosis and Malaria also backed elimination efforts in the region, with a 3-year, $243-million grant. Donors such as the Bill & Melinda Gates Foundation and the Asian Development Bank will add more than $20 million to the fight this year.

But the rise of cases in northeastern Cambodia shows how difficult getting to zero will be — and how crucial. As long as P. falciparum exists, it can resurge. And the last parasites remaining are the hardest to find. They reside in the hinterlands, borderlands and war zones — and in people who show no signs of the disease. “Malaria is very clever — it hides out where you don’t know and comes back when you aren’t ready,” says Ladda Kajeechiwa, a malaria-programme manager at a branch of the Mahidol Oxford Tropical Medicine Research Unit (MORU) in Mae Sot, Thailand.

2030年までにメコン地域でのマラリア撲滅についての取り組みの概要はこちらでも厚生省のサイトでも説明してくれていました。WHOの英文オリジナルと読み比べることもできます。

マラリアについて （ファクトシート）

2017年11月　WHO　

薬剤耐性

　抗マラリア剤への耐性は、常に浮かび上がる問題です。前世代の薬剤であるクロロキンやスルファドキシン－ピリメサミンに対する耐性熱帯熱マラリアは、1950年代から1960年代にかけて広がり、マラリアの感染制御のための努力を蝕み、子どもが生存の恩恵を得ることから逆行させました。

　WHOは、抗マラリア薬の耐性を定期にモニタリングすることを推奨し、各国によるこの重要な活動領域への取り組み強化を支援しています。　

　アルテミシニン併用療法（ACT）には、アルテミシニンと併用薬とが含まれています。近年、アルテミシニン耐性の原虫が大メコン圏のカンボジア、ラオス、ミャンマー、タイ、ベトナムの5か国で報告されています。研究では、アルテミシニン耐性がこの圏内の多くの地域で独自に出現していることが確認されています。

　2013年に、WHOは、大メコン圏でのアルテミシニン耐性（ERAR）原虫に対する緊急対策を開始しました。この対策は、薬物耐性原虫の拡散を抑制し、マラリアのリスクに曝されているすべての人々のための救命手段を提供することで、高いレベルで（蚊を）駆除する計画によるものです。それでも、この活動が実施されている中で、小規模の地域の新たな地図領域で、独立して、新たな耐性（原虫）の発生地が現れてきました。また、いくつかの発生状況では、アルテミシニンの併用薬に耐性を示す原虫が出現してきました。マラリアの変化に対応するために、新たなアプローチが必要となりました。

　そのため、2014年9月にWHOのマラリア政策諮問委員会は、2030年までにこの圏内から熱帯熱マラリアを撲滅するという目標を採択し勧告しました。2015年5月の世界保健総会で、この圏内すべての国の承認の下に、WHOは大メコン圏（2015年から2030年まで）からのマラリア撲滅作戦を開始しました。WHOからの技術的なガイドラインに基づき、大メコン圏のすべての国々が各国のマラリア撲滅計画を作成しました。WHOは、支援組織との協力の下で、ERARから発展させた新たな主導組織、メコン圏マラリア撲滅計画を通じて、引き続き、各国の蚊の撲滅への取り組みを支援していきます。

Antimalarial drug resistance

Resistance to antimalarial medicines is a recurring problem. Resistance of P. falciparum to previous generations of medicines, such as chloroquine and sulfadoxine-pyrimethamine (SP), became widespread in the 1950s and 1960s, undermining malaria control efforts and reversing gains in child survival.

WHO recommends the routine monitoring of antimalarial drug resistance, and supports countries to strengthen their efforts in this important area of work.

An ACT contains both the drug artemisinin and a partner drug. In recent years, parasite resistance to artemisinin has been detected in 5 countries of the Greater Mekong subregion: Cambodia, Lao People’s Democratic Republic, Myanmar, Thailand and Viet Nam. Studies have confirmed that artemisinin resistance has emerged independently in many areas of this subregion.

In 2013, WHO launched the Emergency response to artemisinin resistance (ERAR) in the Greater Mekong Subregion, a high-level plan of attack to contain the spread of drug-resistant parasites and to provide life-saving tools for all populations at risk of malaria. But even as this work was under way, additional pockets of resistance emerged independently in new geographic areas of the subregion. In parallel, there were reports of increased resistance to ACT partner drugs in some settings. A new approach was needed to keep pace with the changing malaria landscape.

Consequently, WHO’s Malaria Policy Advisory Committee in September 2014 recommended adopting the goal of eliminating P. falciparum malaria in this subregion by 2030. WHO launched the Strategy for Malaria Elimination in the Greater Mekong Subregion (2015–2030) at the World Health Assembly in May 2015, which was endorsed by all the countries in the subregion. With technical guidance from WHO, all GMS countries have developed national malaria elimination plans. Together with partners, WHO will provide ongoing support for country elimination efforts through the Mekong Malaria Elimination programme, a new initiative that evolved from the ERAR.

長く、重く、堅い内容の記事ですが、データや現地の写真も載せてくれていますので、そちらだけでも見てもらってもいいかもしれません。