Infectious Disease Alert Updates
By Carol A. Kemper, MD, FACP
Dr. Kemper reports no financial relationships relevant to this field of study.
Travelers Unaware of the Need for Pre-travel Vaccinations
SOURCE: Hyle EP, Rao SR, Jentes ES, et al. Missed opportunities for measles, mumps, rubella vaccination among departing U.S. adult travelers receiving pre-travel health consultations. Ann Intern Med 2017;167:77-84.
Outbreaks of measles continue to occur in the United States, mostly because of imported cases. More than half of these occur as the result of inadequately vaccinated returning U.S. travelers who acquire measles infection abroad. And the problem is not limited to those returning to the United States. This column recently commented that, on any given day, only 86% of persons at Disneyland have received MMR vaccine — far below the threshold for herd protection in the event of an outbreak. The recent measles outbreak at Disneyland in Anaheim, CA, in 2014-2015 resulted in 125 measles infections, 110 of which occurred in Californians. Nearly half (45%) were unvaccinated, most for non-medical exemption.
These authors surveyed 54,100 departing U.S. adult travelers for measles immunity and eligibility for MMR between 2009 and 2014. Travelers were evaluated at one of 24 sites with Global TravEpiNet (GTEN), which is a consortium of travel clinics, 14 of which are based at academic centers and 10 at primary care practices, public health facilities, or pharmacies. Travelers born before 1957 were considered immune and excluded from analysis (n = 13,290 adults). Of those remaining, the median age was 33 years (range, 26 to 44 years). The most common travel destinations included Africa (35%) or Central or South America (28%), and the median duration of planned travel was two weeks.
Most travelers born after 1957 were deemed to be measles-immune (84%), based on a history of receiving two doses of measles vaccine (73%), serologic testing (10%), and/or a history of measles infection (3%), and/or provider judgment (18%). Only a small number (0.3%) were ineligible for vaccination for medical reasons. The remaining 16% were eligible for MMR.
MMR was offered to anyone eligible for vaccination; 53% did not receive MMR during their visit. The most common reason was patient refusal (48%). In 28% of cases, vaccination was not provided based on provider decision — 94% of the time because the provider thought the vaccine was unnecessary and 6% of the time because of insufficient time before travel. “Health system barriers” were listed as the reason for non-vaccination in 24% of cases, largely due to referral to an outside provider.
For the 1,698 travelers who refused the vaccine, three-fourths indicated they were “not concerned about illness,” 20% were concerned about vaccine safety, and a small percentage (6%) were concerned about vaccine cost.
Many travelers remain unaware of the risks of illness abroad and the need for good travel advice and immunization. Too often, I’ve argued with patients who weigh the imagined risk of illness against the inconvenience and expense of vaccination, and lost the argument. This survey also demonstrates that at least one-fourth of missed MMR vaccine was the result of provider decision, suggesting that travel clinic providers would benefit from additional education about the benefits and need for MMR vaccination in eligible travelers.
Fecal Microbiota Testing
SOURCES: Saey TH. Here’s the poop on getting your gut microbiome analyzed. Science News, June 17, 2014; Rabin RC. Can I test the health of my gut microbiota? New York Times, July 7, 2017.
Just Google “gut microbiota testing” and see the array of possible “gut report” kits out there for purchase. Send in a sample and pay a fee — usually $100 or more — and you will receive a profile of your gut microbiome, with lots of detailed information and colorful graphics on the dominant species populating your gut. Your fecal microbiota will be compared to the “normal” profiles of other Americans or people in other parts of the world, vegetarians, or those who follow different diets. The problem is that little is known about the typical genomic profile of the gut or what is “normal.” There’s obviously tremendous diversity, even in healthy people. Researchers have determined that persons with diabetes or inflammatory bowel disease — or people who have received recent antibacterial therapy — may have very different microbiota profiles. Unfortunately, no one really knows what these differences mean in terms of your overall health.
Different methodologies also may offer differing results. Saey submitted stool samples to two companies for testing and received wildly different results.
Increasingly, we are seeing outfits that offer molecular testing of blood, stool, or other specimens, but with little credibility or science behind it. And yet, patients looking for an explanation for their symptoms or an illness will latch on to anything. A young Stanford graduate student who felt “fuzzy-headed” for more than a year recently spent $1,000 on specialized “molecular” testing of his blood and stool, only to be disappointed when I explained the results were basically uninterpretable.
Newer Guidelines for Influenza Testing This Season
SOURCES: California Department of Public Health. Testing and treatment for patients hospitalized with suspected influenza. Oct. 2, 2017; Merckx J, Wali R, Schiller I, et al. Diagnostic accuracy of novel and traditional rapid tests for influenza infection compared with reverse transcriptase polymerase chain reaction: A systematic review and meta-analysis. Ann Intern Med 2017;167:394-409.
As we approach flu season, I like to remind providers that rapid influenza diagnostic tests are imperfect — and before ordering a rapid flu test, consider the likelihood of a positive result. Do they plan to treat the patient or the test result?
Merckx and associates performed a meta-analysis of more than 162 diagnostic studies, comparing the diagnostic accuracy and sensitivity of rapid influenza diagnostic tests (RIDTs) with immunoassays (DIAs) and nucleic acid amplification tests (NAATs) in children and adults with influenza-like illness (ILI). The overall results confirm what we already know: RIDTs are helpful in providing a rapid result for many patients, but false-negative results are common. Pooled sensitivities for detecting Influenza A using RIDTs were 54%, compared with 80% for DIAs and 91.6% for NAATs. Pooled sensitivities for detecting Influenza B were similar: Using RIDTs they were 53%, compared with 77% for DIAs and 95% for NAATs. Pooled sensitivities generally were higher in pediatric patients compared with adults.
Keep in mind that false negatives are common when flu is more frequent in your community — and false positives are more common when flu is less frequent.
The California Department of Public Health and Centers for Disease Control and Prevention have recommended that, regardless of the results of prior rapid influenza testing, empiric therapy with a neuraminidase inhibitor should be administered promptly to patients hospitalized with ILI or suspected influenza, and not necessarily discontinued simply because an RIDT result may be negative. NAAT testing or RT-PCR testing should be performed in all suspect cases, and many hospitals have an RT-PCR panel for respiratory virus, which can be helpful. Although treatment has shown the greatest benefit when initiated within 48 hours of onset of illness, evidence supports the administration of antiviral therapy when begun later than 48 hours in those hospitalized with severe flu.
Travelers Unaware of the Need for Pre-travel Vaccinations; Fecal Microbiota Testing; Newer Guidelines for Influenza Testing This Season
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