性感染症が男性間で流行～同性愛者の無防備な行為が原因

更新2005年11月10日 19:26米国東部時間
性感染症が男性間で流行～同性愛者の無防備な行為が原因 - USフロントライン

　同性愛の男性による無防備な性交渉が原因で、梅毒の感染が国内で急速に広まっている。また、一般的な抗生物質が効かない淋病患者が増えていることも分かった。米疾病対策センター（CDC）が明らかにした。

　ロサンゼルス・タイムズによると、女性とマイノリティ（少数人種）の性病感染率が減少傾向にある一方で、男性同性愛者の感染率が増えている。性病は、国内患者数が2000万人近くに上る深刻な問題で、エイズ・ウイルス（HIV）を含む性病の治療コストは年間130億ドルに達する。

　1990年代、各種保健機関が対策に乗り出した影響で梅毒の感染者は減少し、2000年には統計を取り始めた1941年以来、新規感染者が最少となった。ところが00年から04年にかけて感染者は29％も増え、7980人を数えた。感染者のほとんどが男性だった。また、04年に梅毒に感染した人の64％は男性の同性愛者で、約５％だった99年から急増している。

　性病感染の流行は、治療が難しいエイズ感染の増加につながるため、専門家は懸念を深めている。CDC性感染症予防部門のロナルド・ボルディセリ氏によると、危険な性交渉が増えた原因の１つには、覚せい剤メタンフェタミンの流行がある。

　04年、梅毒患者の割合が最も高かった都市はサンフランシスコで、人口10万人中梅毒患者が45.9人だった。次がアトランタの34.6人、ボルティモアの33.2人と続く。

　一方、淋病患者の割合は10万人中113.5人（全米で約33万人）で、1941年以来最低となった。ただし04年は、淋病の治療でまず与えられる抗生物質フルオロキノロンが効かなかった患者の割合が前年の4.1％から6.8％に増えた。男性の同性愛者では薬に耐性を持つ割合が23.8％と、異性愛者の８倍にも上る。

　一般的な性病ではクラミジアの感染者も増えており、04年は5.9％増の92万9462人（10万人中319.6人）となった。クラミジアの場合、自覚症状がない人も多いため、実際の感染者数は最高で280万人と推測されている。

　すべての性病感染者数は、累計で約1900万人に上り、うちおよそ半数が15～24歳。



Gay Sex Called Key to Rise in Syphilis
By Thomas H. Maugh II
Los Angeles Times Staff Writer
November 9, 2005

Men engaged in risky homosexual activity are fueling a sharp increase in the incidence of syphilis and a smaller but worrisome rise in gonorrhea resistant to common antibiotics, federal researchers said Tuesday.

The increases are seen at a time when sexually transmitted disease rates among historically important risk groups, especially women and minorities, have been declining, according to a new report from the Centers for Disease Control and Prevention.

The diseases "are a significant and ongoing threat to millions of Americans," said Dr. Ronald O. Valdiserri, acting director of CDC's National Center for HIV, STD and TB Prevention. They cost the healthcare system $13 billion per year, he said.

Health authorities made major inroads into slowing syphilis transmission during the 1990s, bringing the annual number of new cases during 2000 to the lowest level since recordkeeping began in 1941.

Between 2000 and 2004, however, the rate rose by 29% to a total of 7,980 cases, with most of the increase occurring among men.

Men engaging in homosexual activities accounted for 64% of syphilis infections in 2004, compared with about 5% in 1999, said Dr. John M. Douglas Jr., director of the CDC's division of sexually transmitted disease prevention.

Although the number of cases is small, experts say the data are worrisome because increases in sexually transmitted diseases are thought to be precursors of increases in the transmission of the AIDS virus, which is much more difficult to combat.

"We have very good and sound information showing increases in high-risk behaviors among men having sex with men since 1999," fueling the increase in syphilis, Valdiserri said.

Risky behavior has increased because of growing crystal methamphetamine use, he said — first on the West Coast and now on the East.

"That's exacerbating the transmission of syphilis," he said.

As in previous years, San Francisco had the highest incidence of syphilis, with a rate of 45.9 cases per 100,000 people. Atlanta was second with 34.6 cases, and Baltimore third with 33.2. Los Angeles ranked 24th, with five cases per 100,000.

Gonorrhea rates, in contrast, have fallen to 113.5 cases per 100,000 people in 2004 — about 330,000 cases — the lowest rate since 1941. Nonetheless, surveillance by the CDC in selected cities has shown that resistance to fluoroquinolone antibiotics — the common first-line treatment for gonorrhea — increased from 4.1% in 2003 to 6.8% in 2004.

Also, the rate of antibiotic resistance among men engaging in homosexual activity was 23.8% — eight times the rate in heterosexuals.

Last year, the CDC recommended that fluoroquinolones no longer be used to treat the disease in men having sex with men because of the rise in resistance. They also are not recommended for use in California and Hawaii, where resistance has been widespread for years.

The reported incidence of a third sexually transmitted disease, chlamydia, also rose 5.9% last year to 319.6 cases per 100,000 people — a total of 929,462 cases.

But Valdiserri and Douglas attributed much of that growth to new and more aggressive screening programs rather than to increased transmission.

Nonetheless, the report says that the majority of cases are still not detected or reported to the agency because of the absence of symptoms, and that the actual number of infections is as high as 2.8 million cases per year.

"Healthcare providers urgently need to step up screening for chlamydia, particularly among young, sexually active women, who are at greatest risk of infertility if the disease is not diagnosed and treated," Douglas said.

The two other most common sexually transmitted diseases in the United States, herpes and human papilloma virus, are not reported to federal authorities, although reliable estimates of their prevalence are available from other sources.

Taking those diseases into account, Valdiserri said, the total number of sexually transmitted diseases in the United States each year is about 19 million, almost half of them among people ages 15 to 24.