刚果民主共和国的人感染猴痘病例的增加可能被归结于终止了常规的天花疫苗接种。天花疫苗提供了针对猴痘病毒的交叉保护免疫力，猴痘病毒是天花病毒的一种亲缘病毒，它导致了类似于天花的人类疾病。在2006年到2007年间，Anne Rimoin及其同事在刚果民主共和国的9个卫生区域开展了一项猴痘监测项目，并把他们的发现与在1981年到1986年进行的一次类似的研究进行了比较。

这组作者报告说，20世纪80年代进行的那次研究的两个得到了最多监测的地区在30年的时间里猴痘发病增长到了原来的20倍，其中9/10的病例来自1980年之后出生的人，那时候大规模的天花疫苗免疫接种在刚果民主共和国终结了。这组科学家计算出1980年之前出生的人感染猴痘的可能性是1980年后出生的人的1/5，且疫苗提供针对猴痘的免疫的有效率是80%。这组作者警告说，全世界的人口如今大部分未接种天花疫苗，而且2003年美国暴发的人类猴痘——从进口自加纳的啮齿动物传播给了美洲草原土拨鼠——证明了这种病毒能够离开非洲中部并通过动物宿主在全球传播。

原文出处：

PNAS doi: 10.1073/pnas.1005769107

Major increase in human monkeypox incidence 30 years after smallpox vaccination campaigns cease in the Democratic Republic of Congo
Anne W. Rimoina,b,1, Prime M. Mulembakanic, Sara C. Johnstond, James O. Lloyd Smithb,e, Neville K. Kisaluf, Timothee L. Kinkelac, Seth Blumbergb,e, Henri A. Thomasseng, Brian L. Pikeh, Joseph N. Fairh, Nathan D. Wolfeh, Robert L. Shongoi, Barney S. Grahamj, Pierre Formentyk, Emile Okitolondac, Lisa E. Hensleyd, Hermann Meyerl, Linda L. Wrightm, and Jean-Jacques Muyemben

Studies on the burden of human monkeypox in the Democratic Republic of the Congo (DRC) were last conducted from 1981 to 1986. Since then, the population that is immunologically na?ve to orthopoxviruses has increased significantly due to cessation of mass smallpox vaccination campaigns. To assess the current risk of infection, we analyzed human monkeypox incidence trends in a monkeypox-enzootic region. Active, population-based surveillance was conducted in nine health zones in central DRC. Epidemiologic data and biological samples were obtained from suspected cases. Cumulative incidence (per 10,000 population) and major determinants of infection were compared with data from active surveillance in similar regions from 1981 to 1986. Between November 2005 and November 2007, 760 laboratory-confirmed human monkeypox cases were identified in participating health zones. The average annual cumulative incidence across zones was 5.53 per 10,000 (2.18–14.42). Factors associated with increased risk of infection included: living in forested areas, male gender, age < 15, and no prior smallpox vaccination. Vaccinated persons had a 5.2-fold lower risk of monkeypox than unvaccinated persons (0.78 vs. 4.05 per 10,000). Comparison of active surveillance data in the same health zone from the 1980s (0.72 per 10,000) and 2006–07 (14.42 per 10,000) suggests a 20-fold increase in human monkeypox incidence. Thirty years after mass smallpox vaccination campaigns ceased, human monkeypox incidence has dramatically increased in rural DRC. Improved surveillance and epidemiological analysis is needed to better assess the public health burden and develop strategies for reducing the risk of wider spread of infection.