June 2016

Emerging Infectious Diseases Journal

Highlights: Emerging Infectious Diseases, Vol. 22, No. 6, June 2016

The articles of interest summarized below will appear in the June 2016 issues of Emerging Infectious Diseases, CDC’s monthly peer-reviewed public health journal. This issue will feature Respiratory Diseases. The articles are embargoed until May 11, 2016, at 12 p.m. EDT.

Note: Not all articles published in EID represent work done at CDC. In your stories, please clarify whether a study was conducted by CDC (“a CDC study”) or by another institution (“a study published by CDC”). The opinions expressed by authors contributing to EID do not necessarily reflect the opinions of CDC or the institutions with which the authors are affiliated.

1. Reemergence of Dengue in Southern Texas, 2013, Dana L. Thomas et al.

Dengue is caused by a virus, which is spread by Aedes aegypti mosquitoes. The illness is common throughout the tropics and subtropics and can occur in travelers returning to the United States from these regions. In the southern United States, dengue outbreaks occurred regularly from the late 1700s until the 1940s but stopped after an aggressive campaign eliminated those mosquitoes from much of the country. After the campaign ended, however, mosquito populations surged, and more dengue outbreaks resulted. The next 3 dengue outbreaks in Texas since 1980 were all associated with epidemics in northern Mexico. Therefore, when a dengue epidemic occurred in northern Mexico in 2013, dengue tracking (surveillance) and laboratory testing in southern Texas were enhanced. Of 53 dengue patients identified, about half had been infected with dengue virus in Texas and the other half had been infected in Mexico before returning to Texas. Because Aedes aegypti mosquito populations are established in Texas and because in 2013 alone, around 27 million travelers crossed the Mexico border into southern Texas, future dengue epidemics in northern Mexico are likely to also occur in southern Texas. Residents of southern Texas should therefore empty, cover, or dispose of mosquito breeding sites (e.g., discarded tires, rain barrels, buckets) and use mosquito repellent and window screens or air-conditioning to avoid mosquito bites. For patients suspected to have dengue, clinicians should order 2 types of testing (molecular and serologic), and positive results should be reported to public health authorities.

Contact:CDC Press Office, 404-639-3286 or media@cdc.gov

2. Improved Global Capacity for Influenza Surveillance, Lauren S. Polansky et al.

Multi-country outbreaks of highly pathogenic avian influenza H5N1 in birds during 2004 and humans in 2005 served as a call to action to strengthen influenza surveillance around the world. From 2004–2009, CDC and 39 national governments took measures to strengthen the capacity of 2 systems: laboratory testing (which detects seasonal and novel or non human influenza viruses) and sentinel surveillance (which detects cases of illness). To evaluate progress, in 2013, CDC analyzed WHO data and sent a questionnaire to 35 countries. Findings indicated substantial increases in laboratory and sentinel surveillance capacities. Many parts of the world are now better equipped to routinely know which influenza viruses are circulating, to detect emergence of novel influenza viruses, to identify which viruses to use for vaccine, and to better understand associated illnesses. In addition to these benefits, the increased capacity for influenza surveillance has potential uses for other infectious diseases.

Contact:CDC Press Office, 404-639-3286 or media@cdc.gov

3. Heterogeneous and Dynamic Prevalence of Asymptomatic Influenza Virus Infections, Luis Furuya Kanamori et al.

The role played by asymptomatic influenza virus infections in transmission of the virus requires further study. Outbreak/pandemic preparedness is contingent on stockpiling of sufficient vaccine and this threshold is currently determined by calculations that assume a single, constant value for the asymptomatic proportion of infections. To find out the proportion of people who had asymptomatic infections, investigators conducted a systematic review and meta-analysis of 55 studies. This effort revealed extensive heterogeneity among the studies, and this heterogeneity could not be explained by the type of influenza virus, the laboratory tests used to detect the virus, the year of the study, or the location of the study. Thus, the findings clearly demonstrate the inappropriateness of a one-size-fits-all estimate in the planning of interventions to curb the spread of human influenza viruses. As new subtypes and strains emerge, actively surveying infection status of local populations and tracking any changes in asymptomatic rates of infection should increasingly become a global health priority.

Contact: James Barr, London School of Hygiene and Tropical Medicine Press Office, James.Barr@lshtm.ac.uk

4. Extended Human-to-Human Transmission during a Monkeypox Outbreak in the Democratic Republic of the Congo, Leisha Diane Nolen et al.

Monkeypox virus is endemic to western and central Africa. A close relative of the variola (smallpox) virus, monkeypox virus causes a smallpox-like infection but is less severe than smallpox. Most patients initially experience fever, followed by rash a few days later. However, up to 11% of unvaccinated affected persons die from the disease. In 2013, a 600-fold increase in monkeypox cases reported from the Democratic Republic of the Congo prompted an outbreak investigation, which identified 104 possible cases and confirmed 50 of the 60 suspected cases for which laboratory testing was conducted. The household attack rate (i.e., rate of persons living with an infected person who experienced symptoms of monkeypox) was 50%. Nine families reported more than 1 transmission event. The high attack rate and transmission observed in this study underscore the importance of surveillance and rapid identification of monkeypox cases. Community education and training are needed to prevent transmission of the virus during outbreaks.

Contact:CDC Press Office, 404-639-3286 or media@cdc.gov

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES