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Novel orthopoxvirus discovered in Alaska patient
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Investigators for the CDC and the Alaska Division of Public Health discovered that a patient living in a remote area of Alaska was infected with a novel species of orthopoxvirus.
The investigation, conducted in September 2015, was presented as part of the CDC’s Epidemic Intelligence Service Conference in Atlanta.
Figure 1. Photo of Yuri P. Springer, PhD, taken in Alaska.
Source: David Hoekman, PhD
Yuri P. Springer, PhD, a CDC Epidemic Intelligence officer who led the study, told Infectious Disease News that the orthopoxvirus — detected by CDC labs in samples taken from a suspicious papulovesicular lesion on the patient’s back — was “quite genetically unique.”
“In spite of being linked to a human infection in North America,” Springer said, “our analysis showed that it is not a close genetic relative of the three species of orthopoxvirus classified as having a North American association. Instead, it is more closely related to Old World orthopoxviruses, yet is also genetically quite distinct from this group.”
Since 1980, when routine vaccination against smallpox was discontinued worldwide, vaccine-derived immunity has waned and other orthopoxvirus-associated infections in humans have emerged.
According to Springer, at least four other novel poxviruses have been characterized over the past few years, including the most recently discovered orthopoxvirus, which was isolated by two other CDC investigators from two human cases in the Republic of Georgia in 2013. In that case, blood tests on the patients’ cows, as well as captured rodents and shrews, showed exposure to the virus. Investigators suspected that the cows were incidental hosts, and the natural reservoirs were small mammals.
Springer said novel poxviruses are periodically discovered during sampling of wild rodent populations.
In the Alaska case, wild rodents were reported to be abundant around the patient’s home and occasionally found inside, but none of the 23 environmental samples —including small mammal feces — tested positive for the virus via quantitative real-time PCR.
Further, although investigators tested four contacts of the patient, no additional human cases were found. Investigators said the patient had not recently traveled outside of Alaska.
“This investigation identified a novel species of orthopoxvirus in an Alaska resident whose travel history was inconsistent with importation of the virus into the state,” the investigators concluded. “Given orthopoxviruses emergence in the absence of routine smallpox vaccination, orthopoxvirus testing should be performed on persons with an illness consistent with poxvirus infection.” – Gerard Gallagher
References:
Springer YP, et al. Alaska resident infected with a novel species of orthopoxvirus – Alaska, 2015. Presented at: Epidemic Intelligence Service Conference: May 2-5, 2016; Atlanta.
Vora NM, et al. N Engl J Med. 2015;doi:10.1056/NEJMoa1407647.
Disclosure: The researchers report no relevant financial disclosures.