A study describes several imported measles events in which infected travelers triggered additional cases after returning to Washington state or South Carolina. In one cluster, infections spread through schools, medical facilities, churches and public places, while another produced seven genetically similar cases. Officials said quarantine, isolation and contact tracing helped prevent further transmission. The findings also challenge claims that the United States’ current surge is primarily the result of infections arriving from abroad.
Imported cases and domestic spread
In the second imported event, a South Carolina resident visited a public place while infected. Four South Carolina residents who had close contact with the visitor subsequently became ill. Although they were contagious, those four residents visited schools, medical facilities and churches. Nine of their contacts, along with one person exposed in public, also became ill, resulting in a total of 14 clusters between January 15 and February 17.
In the third imported incident, two state residents returned from South Carolina and became ill between January 15 and 16. No additional cases were associated with them.
A fourth importation event occurred after another resident returned from a trip. That person followed isolation and quarantine recommendations, and no associated cases were reported.
In the fifth imported case, a Washington state resident returned from out-of-state travel, came into contact with a close contact and became ill on January 19. Despite being contagious, he visited schools and medical facilities. Six close contacts developed symptoms, producing a cluster of seven cases that lasted from January 19 through January 29. Genomic sequences from five of the cases were nearly identical to the sequence identified in South Carolina.
Officials credited basic public health measures—including quarantine, isolation and contact tracing—with preventing further spread of the virus.
Conflict with Kennedy
The study illustrates how easily the virus can spread between communities as vaccination rates decline. It also contradicts a recurring claim from Health Secretary Robert F. Kennedy Jr., a prominent anti-vaccine advocate.
Kennedy has downplayed the current measles surge in the United States and forcefully rejected suggestions that decades of anti-vaccine misinformation and disinformation are contributing to rising case numbers and falling vaccination rates.
Instead, Kennedy has argued that there is a “global pandemic” and that the United States is “doing better than any other country in the world in controlling the measles outbreak.” Both claims are false. Dozens of other countries have lower infection rates than the United States. Neighboring Canada and Mexico are among the countries also experiencing large increases in cases, but the rise in the United States is not attributed to imported infections from abroad. Instead, the study links it to domestic transmission in undervaccinated communities.
According to data from the Centers for Disease Control and Prevention, 18 of the 4,588 measles cases confirmed in the country this year were reported among overseas visitors. A total of 4,404 cases, or 96 percent, were associated with domestic outbreaks. The source also reports 43 new cases of infectious disease in the United States this year.
Source: arstechnica.com
