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On Call for Diphtheria, MERS

Division of Bacterial Diseases (DBD) News Bulletin

Fall 2013

On Call 24/7 for Diphtheria

Once a major cause of illness and death among children, diphtheria is now nearly unheard of in the United States and serves as an example of the benefit of vaccination.

With fewer than 55 U.S. cases reported to CDC since the 1980s, most physicians today have never seen a case of diphtheria and few scientists work on this increasingly rare disease. In light of this, many people are often surprised to learn about CDC’s diphtheria activities and the unique challenges that come with a disease being so uncommon.

Diphtheria Work Leads to International Collaborations

While diphtheria is well controlled in the United States, it is still an important global public health issue. The disease is endemic in several countries while others continue to experience sporadic outbreaks—cases often occur in large areas or among pockets of unvaccinated or inadequately immunized populations. CDC provides epidemiologic and laboratory support to countries at their request, either in person or remotely. Most recently, MVPDB staff collaborated with the World Health Organization (WHO) and local health ministries during visits to Laos (2013), Indonesia (2010), and Haiti (2010). Pictured here, a team conducts patient interviews in the home of a village leader during an outbreak investigation in Huoaphang Province, Laos. CDC, WHO’s Laos country office, and the district’s surveillance group worked in close collaboration during the investigation.

Co-investigator from WHO’s country office for The Lao People's Democratic Republic, a diphtheria patient (boy) and his mother, the district surveillance officer, DBD’s Tej Tiwari, and the village leader (pictured left to right).

Photo: Co-investigator from WHO’s country office for The Lao People's Democratic Republic, a diphtheria patient (boy) and his mother, the district surveillance officer, DBD’s Tej Tiwari, and the village leader (pictured left to right).

“Continuous vigil by healthcare providers is still a necessity,” says Tej Tiwari, an epidemiologist with DBD’s Meningitis and Vaccine Preventable Diseases Branch (MVPDB) who has worked on diphtheria since 2001. “Given that diphtheria continues to occur in many developing countries, the increasing volume of global travel, and the presence of susceptible people in the United States — the potential for importation is very real.”

When a case is suspected, early and prompt treatment is critical to reducing the complications caused by the potent toxin that diphtheria bacteria produce. That is where CDC and the DAT pager come into play. DAT stands for diphtheria antitoxin and only CDC is authorized to distribute it in the United States.

MVPDB staff members are on call 24/7 to respond to physician requests for the life-saving treatment. They discuss the case-report with the physician and decide together whether DAT treatment is appropriate. If indicated, CDC releases DAT from the nearest U.S. Public Health Service quarantine station so it gets to the patient as quickly as possible. Typically there are fewer than five DAT releases each year.

Only a few countries in the world currently produce DAT and CDC is finding it increasingly difficult to acquire it. This highlights the need for new research to find an alternative to DAT.

Due to the low number of cases in the United States, local capacity to test for and confirm diphtheria is also decreasing. CDC’s Pertussis and Diphtheria Laboratory (PDL) provides laboratory support to health departments when a case is suspected.

Each year, PDL receives 10–15 isolates from across the country and has the capability to quickly determine whether or not a suspected case really is diphtheria or not. If an isolate is identified as Corynebacterium diphtheriae (C. diphtheriae), the bacterium that causes diphtheria, the lab then runs a special test—the Elek test.

“Just because C. diphtheriae is isolated from someone, it doesn’t usually mean the person has diphtheria,” explains PDL microbiologist Pam Cassiday, who has worked on diphtheria since 2000. “The Elek test is important because it shows if the isolate produces diphtheria toxin. This toxin is what causes the symptoms in diphtheria.”

Childhood vaccination for diphtheria is high (95% among children in kindergarten according to a recent MMWR report), but there is a lot of room for improvement in adult vaccination rates. In 2011, the proportion of adults receiving any diphtheria toxoid–containing vaccination (i.e., Td or Tdap) during the past 10 years was 65% for adults aged 19–49 years, 64% for adults aged 50–64 years, and 54% for adults aged 65 and older.

These rates leave many adults susceptible to diphtheria. In fact, screening tests conducted since 1977 show that somewhere between 4 to 8 out of every 10 adults over the age of 60 are no longer protected against diphtheria.

Are you up to date? If not, consider getting your booster and help keep diphtheria a distant memory in the United States.

DBD Supports MERS Response

CDC activated its Emergency Operations Center on April 8, 2013, to support the response to MERS-CoV. Middle East Respiratory Syndrome (MERS) is a viral respiratory illness first reported in Saudi Arabia in 2012. It is caused by a coronavirus called MERS-CoV. Most people who have been confirmed to have MERS-CoV infection developed severe acute respiratory illness. They had fever, cough, and shortness of breath. As of November 21, 2013, there have been 157 cases and 66 deaths.

So far, all the cases have been linked to six countries in or near the Arabian Peninsula. No cases have been identified in the United States. This virus has spread from ill people to others through close contact. However, the virus has not shown to spread in a sustained way in communities. The situation is still evolving.

CDC, including several staff from DBD, is working with partners to better understand the risks of this virus, including the source, how it spreads, and how infections might be prevented. CDC has provided information for travelers and is working with health departments, hospitals, and other partners to prepare for possible cases in the United States. Staff members from DBD who have been actively involved in this agency effort include: Chris Van Beneden, Gayle Langley, Manisha Patel, Preeta Kutty, Elizabeth Briere, and Kathleen Dooling.

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