Lab Matters Summer 2017 | Page 8

infectious diseases

The latest example of this is in Minnesota, where a measles outbreak hit 78 confirmed cases as of June 16. The state is typically home to less than a handful of measles cases each year— most years, the case count is between zero and two. At the Minnesota Department of Health’ s Public Health Laboratory, which is the only lab in the state that can do real-time reverse-transcription polymerase chain reaction( rRT-PCR) testing for measles, staff received more than 800 specimens for measles testing between April and June, with a goal of fully processing each one the same day it’ s received. To stop an outbreak, both speed and accuracy are critical.

Fortunately, Minnesota lab workers are trained and ready to provide both. But sustaining that kind of surge capacity over the long run and in the face of new and emerging disease threats is always challenging— even in the best funding environments.

Measle virus

by Kim Krisberg, writer

In the US, rates of vaccine-preventable diseases are so low that many commercial labs don’ t even have the ability to test for them anymore. The shift reflects the hard work of decadeslong immunization efforts. But it also means that when there is a vaccine-preventable outbreak, just about all of our rapid diagnostic capacity resides in one place: the public health lab.

“ We’ ve spent a lot of time increasing our capacity over the last 10 years and we’ re seeing that capacity being put to work,” said Sara Vetter, PhD, manager for infectious diseases at the Minnesota Public Health Laboratory. Vetter noted that Minnesota last experienced a measles outbreak in 2011—“ and that one seemed huge and it was just 26 cases of measles.”

This year’ s measles outbreak was almost entirely concentrated in a Somali community in Minnesota’ s Hennepin County, home to more than 1 million residents. The outbreak officially began on April 10, the same day the lab confirmed the first positive case. Nearly all the cases were among unvaccinated children younger than four years old.

Inside the public health lab’ s Virology / Immunology Unit, technicians tracked the measles outbreak using an rRT-PCR assay, which allows them to detect the highly contagious virus much quicker than private labs that can perform serological testing for measles antibodies. That quickness is key, said Anna Strain, PhD, supervisor of the Virology / Immunology Unit, because it means the health agency’ s epidemiology team