May 2018

Emerging Infectious Diseases Journal

Highlights: Emerging Infectious Diseases, Vol. 24, No. 6, June 2018

Important Note: Not all articles that EID publishes represent work done at CDC or by CDC staff. In your stories, please clarify whether a study was conducted by CDC (“a CDC study”) or by another institution (“a study published by CDC in the EID journal”). Opinions expressed by authors contributing to EID do not necessarily reflect the opinions of CDC or the institutions with which the authors are affiliated. EID requests that, when possible, you include a live link to the actual journal article in your stories. Once the embargo lifts, this month’s articles will be found in the Ahead of Print section of the EID website at

The articles of interest summarized below will appear in the June 2018 issue of Emerging Infectious Diseases, CDC’s monthly peer-reviewed public health journal. This issue will feature zoonoses. The articles are embargoed until May 16, 2018, at Noon Eastern Time.

1. Ferrets as Models for Influenza Virus Transmission Studies and Pandemic Risk Assessments, Jessica A. Belser et al.

Researchers commonly use ferrets to study influenza virus and extrapolate the results to humans. Not only are these animals susceptible to infection with influenza viruses, but they are similar to humans in terms of lung function and clinical signs of influenza virus infection. However, differences in experimental conditions at laboratories around the world can lead to varied results. Researchers addressed those variations as part of a conference on Transmission of Respiratory Viruses in June, 2017. Attendees agreed on the value of standardizing experimental conditions such as handling of the virus (e.g., storage, inoculation protocols), numbers of infected/uninfected ferrets used, and cage conditions (e.g., humidity, temperature, air flow). They also acknowledged limitations posed by using ferrets as proxies for humans, which include variations in individual susceptibility to infection (which could result in different findings for the same experiments) and the limited number of animals that can be studied (because of cost, animal size and associated housing needs, and ethical and practical constraints). Although recent studies with ferrets have greatly expanded knowledge of influenza virus transmissibility, enhanced standardization of experimental conditions would help researchers better compare results and be able to identify novel and emerging influenza viruses and anticipate or prevent pandemics.

Contact: CDC Press Office, or 404-639-3286.

2. Novel Poxvirus in Proliferative Lesions of Wild Rodents, East-Central Texas, USA, Carolyn L. Hodo et al.

Poxviruses can infect birds, reptiles, and mammals, including humans. Often, those viruses are first found in animals and only later found to infect humans. Thus, the finding of unique skin lesions on wild rodents in Texas prompted investigation. Researchers sampled two pygmy mice and used electron microscopy to identify a poxvirus as the cause of the lesions. Genetic analyses indicated that this poxvirus is novel and does not belong to any recognized genus. The new virus was tentatively named Brazospox virus because the infected mice were found near the Brazos River in East-Central Texas. Whether Brazospox virus poses a threat to human health remains to be determined.

Contact: Sarah A. Hamer, Department of Veterinary Integrative Biosciences, Texas A&M University; 979-847-5693 or

3. Rickettsia parkeri in Dermacentor parumapertus Ticks, Mexico, Sokani Sánchez-Montes et al.

Rickettsia parkeri is a bacterium that causes a form of spotted fever group rickettsiosis called R. parkeri rickettsiosis. R. parkeri rickettsiosis is less severe than a Rocky Mountain spotted fever, another spotted fever rickettsiosis. Patients with R. parkeri rickettsiosis typically have fever, headache, rash, muscle pain and a scab at the site of a tick bite called an eschar. All rickettsial diseases, including R. parkeri rickettsiosis can be effectively treated with the antibiotic doxycycline. The bacterium is transmitted to humans primarily by several species of ticks of the genus Amblyomma. Rickettsia parkeri–infected ticks have been identified in six South American countries (Colombia, Peru, Brazil, Bolivia, Uruguay, and Argentina), one Central American country (Belize), and several states in the Southern and Central U.S. However, until now, no studies have found Rickettsia parkeri in ticks in Mexico. During a 2013–2014 study conducted in northwestern Mexico, researchers detected Rickettsia parkeri in Dermacentor parumapertus ticks collected from black-tailed jackrabbits (Lepus californicus). A comparison of gene sequences in this bacterium showed that it was nearly identical to the Black Gap strain of R. parkeri that had been previously reported in D. parumapertus ticks in Texas. Although no confirmed cases of disease in humans have been attributed to R. parkeri Black Gap infections, previous studies have shown that this strain might cause disease in guinea pigs. In addition, its genetic relatedness with the Rickettsia parkeri strain Atlantic rainforest, a well-recognized cause of disease in humans, could have major public health implications in Mexico.

Contact: CDC Media Relations, 404-639-3286 or

4. Novel Focus of Sin Nombre Virus in Peromyscus eremicus Mice, Death Valley National Park, California, USA, Joseph E. Burns et al.

In North America, Sin Nombre virus (SNV) is the most widespread hantavirus and one of the most deadly. SNV typically causes a severe pulmonary illness and ends up killing nearly half of the people it infects. Like most hantaviruses, SNV is predominantly a rodentborne virus. The main carrier of SNV in the western United States is the deer mouse (Peromyscus maniculatus). To assess potential occupational risk to staff and incidental risk to visitors, researchers at the California Department of Public Health (CDPH) conducted rodent surveillance for hantavirus in Death Valley National Park. In the process, they identified cactus mice (Peromyscus eremicus) as another source for SNV infection in the region. Their discovery underscores the importance of controlling rodent populations in and around rural and semirural buildings where risk for contact between rodents and humans is high, even in the absence of Peromyscus maniculatus mice. CDPH shared the study results with park leadership and staff and conducted training on hantavirus awareness and prevention. In addition, CDPH provided pamphlets on hantavirus for park visitors.

Contact: Joseph E. Burns, California Department of Public Health, Vector-Borne Disease Section, via Jorge De La Cruz, CDPH Office of Public Affairs, 916-440-7259 or


Page last reviewed: May 16, 2018