Friday, April 3, 2009

Measles Outbreak in a Hosptial

The National Immunization Conference was well worth the trip to Dallas, despite the hellacious downtown traffic and exorbitant parking fees. One of the more interesting sessions was on the recent US measles outbreaks. Preeta Kutty gave a talk on the outbreak in Arizona.

A little measles background. Prior to the introduction of measles vaccine in the US, between three and four million people were infected annually. Of these, about 48,000 required hospitalization, and 450ish died. Now we see less than 100 cases per year, and almost all of those are epidemiologically linked to imported cases. Looking at the genetic sequencing of the measles isolates, we can further discern that the virus was imported by linking it back to known endemic strains. Presently, measles is not endemic in the US – thanks to the vaccine. Despite all this, MMR uptake has been declining recently due to the concerns over a hypothesized MMR-autism link, leaving pockets of vulnerable populations. When an imported case is introduced into one of these pockets, we have seen several generations of transmission. I have lots to write about MMR and autism (another hot topic at the conference), but that will be in a different post.

Worldwide, measles continues to be a significant cause of morbidity and mortality. The World Health Organization reports that in 2007, there were 197,000 deaths from the disease. There continues to be a global initiative to eliminate measles from the earth; however, one wonders how much progress will be lost due to safety concerns over the vaccine.

At any rate. Last year, a traveler from Switzerland brought measles to Arizona. The patient made multiple visits to an emergency room before proper diagnosis – she was at first sent home with a “viral syndrome.” During those visits, she was never masked (measles spreads most commonly through coughing). Because measles was not recognized at first, the patient was not placed under isolation. Fourteen people altogether were infected. Six of them caught measles nosocomially – that is, from being in the hospital with the index case. Another case caught it in a pediatrician’s office. Interestingly, the hospital did not have record of immunity among the health care workers. They ended up requiring proof of vaccine or positive titer checks. This resulted in a delay in vaccination of susceptible health care workers. Four hundred people were vaccinated at the hospital. In total, estimates are that 4269 patients, 1872 healthcare workers, and 410 others were exposed to measles.

Lessons learned here? First off, if you are in charge at a healthcare facility – any healthcare facility – make sure you know the immune status of your employees (all of them). They should either provide proof of vaccination or positive titers. Some facilities forgo the proof option altogether any have them show positive titers. A tedious and expensive process to be sure, but better than ended up in a blog as the hospital with the nosocomial measles outbreak. Ok, that was mean. I really feel for their infection control and occupational health folks. I know they had to have had a rough time with all this.

Next, we need to continue educating our healthcare workers about the signs and symptoms of measles. In their defense, measles is hard to detect in the prodromal period, especially in the absence of Koplik’s spots. All the worse when you would have no reason whatsoever to suspect measles. Still, lots and lots of healthcare workers have never seen an actual case of measles (frankly, I haven’t), or a lot of other vaccine-preventable diseases.

The final lesson here is to ensure that cases are isolated and that public health is contacted upon suspicion, not conformation. Time between suspicion and conformation can be several days depending on your lab resources. If you wait for conformation to start implementing control measures, you have the potential to end up with a lot of cases.

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