Smallpox Vaccine Effective for Monkeypox

Researchers using a sensitive immunoassay to study the 2003 outbreak of monkeypox in the United States have found that while 72 cases had been reported, the actual number of individuals who contracted the disease was probably much greater, since those who had been vaccinated against smallpox did not develop symptoms of monkeypox.

Investigators at the Oregon Health & Science University (Beaverton, OR, USA) tested sera from individuals exposed to monkeypox during the 2003 Wisconsin outbreak. Those who had contracted the disease, whether or not they became ill, were detected with a highly accurate enzyme-linked immunosorbent assay (ELISA) that demonstrated 95% sensitivity and 90% specificity.

Results published in the August 7, 2005, online edition of Nature Medicine indicated that the 2003 monkeypox outbreak probably extended beyond the officially recognized 72 cases. This conclusion was based on the identification of three previously unreported cases of monkeypox in individuals at 13, 29, and 48 years after smallpox vaccination. These individuals were unaware that they had been infected because they did not experience any recognizable disease symptoms.

"Our research demonstrates that the limitations of currently used technology likely allowed monkeypox cases to slip through the system. This problem was further exacerbated by the two-week delay that occurred during the diagnosis of the first monkeypox cases,” explained senior author Dr. Mark Slifka, assistant professor of molecular microbiology and immunology at Oregon Health & Science University. "If the 2003 outbreak had been smallpox instead of monkeypox, the situation could have been much worse because secondary spread of the virus to other victims would likely have occurred before the outbreak was recognized.”



Related Links:
Oregon Health & Science Univ