Tuesday, November 19

Oregon measles outbreak grows to 25 cases in 3 counties

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By Amber Roman

09 Aug 2024, 16:46 PM EDT

In Oregon’s Willamette Valley, a measles outbreak has affected 25 people, all of them unvaccinated, state health officials said Thursday. The outbreak, which is unusual despite the virus’s high contagiousness, highlights growing concern about declining vaccination rates in the region, which has led to a series of outbreaks in recent years.

The origin of this outbreak dates back two months, when an unvaccinated adult in Marion County contracted the virus. This adult then transmitted the disease to an unvaccinated child in the same household. Since then, the virus has spread, with 16 cases in Marion County, eight in Clackamas County, and one in Multnomah County. Of those 25 cases, five are adults over the age of 20, while the others are younger than 20, said Dr. Paul Cieslak, chief medical officer for the Oregon Health Authority.

Dr. Cieslak noted that this is the largest outbreak in the state since 2019, when 28 cases were confirmed. At that time, Clark County, across the Columbia River, also faced a larger outbreak. Measles, an extremely contagious disease, is transmitted through the air and can remain viable in the environment for up to two hours after an infected person has left the area. This characteristic, coupled with the fact that people can be contagious for up to four days before the characteristic rash appears and for up to four days afterward, makes measles particularly dangerous for communities with low vaccination rates.

Measles symptoms include fever, cough, runny nose and red eyes, followed by a rash that starts on the face and spreads to the rest of the body. These symptoms can appear anywhere from 7 to 21 days after exposure to the virus, meaning a person may be spreading the disease before they are aware they are infected.

Health officials warn that measles can be deadly, especially for those who have not been vaccinated, pregnant women, infants under one year old and people with weakened immune systems. Before the introduction of the measles vaccine, the virus caused 400 to 500 deaths annually in the United States, according to the Centers for Disease Control and Prevention (CDC). Thanks to vaccination campaigns, measles was declared eliminated in the United States in 2000.

However, Dr. Cieslak noted that vaccination rates in Oregon have declined significantly since then. Before 2019, the last significant measles outbreak in the state occurred in the 1990s, a time when Oregon enjoyed very high vaccination rates and a high level of herd immunity. That has changed in recent years, with an increase in the number of parents opting for nonmedical exemptions to avoid vaccinating their children. During the last school year, nearly 9% of kindergartners in Oregon obtained a nonmedical exemption, a significant increase from about 1% before 2000.

This decline in vaccination rates jeopardizes the herd immunity needed to prevent the spread of highly contagious diseases like measles. Clackamas County Health Officer Dr. Sarah Present underscored the seriousness of the situation, noting that large numbers of unvaccinated people can put their communities at risk.

Finally, health officials urge people experiencing measles symptoms to contact a health care provider before visiting any health care facility, in order to avoid exposing others to the virus. This outbreak underscores the critical importance of vaccination to protect communities and prevent preventable diseases like measles from re-emerging and causing harm.

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