Endemic in the Amazon region, recent spread of the disease caused the CDC to issue recommendations to travelers who develop symptoms after visiting certain countries
Anatomic pathologists, microbiologists, and clinical laboratories active in infectious disease testing will want to stay informed about the worldwide progression of the Oropouche virus. The infectious pathogen is spreading beyond the Amazon region (where it is endemic) into more populated areas—including the US—and possibly being transmitted in novel ways … including through sexual activity.
The virus primarily spreads to people through biting small flies called midges (a.k.a., no-see-ums), according to a CDC Health Alert Network (HAN) Health Advisory, which added that mosquitoes can also spread the disease.
Oropouche infections, the CDC said, are occurring in Brazil, Bolivia, Peru, Columbia, and Cuba. Cases identified in the US and Europe seem to be among travelers returning from those countries. Reported cases also include deaths in Brazil and cases of mother-to-child (vertical) transmission.
There is “an increase in Oropouche virus disease in the Americas region, originating from endemic areas in the Amazon basin and new areas in South America and the Caribbean,” CDC noted in its Health Advisory.
Though de Oliveira notes that a global outbreak is not yet expected, researchers are nevertheless raising the alarm.
“The challenge is that this is such a new disease that most clinicians—including infectious disease specialists—are not aware of it and we need to make more patients and healthcare providers aware of the disease and increase access to diagnostics so we can test for it,” said David Hamer, MD (above), infectious disease specialist and professor, global health, at Boston University School of Public Health, in an NPR article. “Over the next year, we are going to learn a lot more.” Pathologist, microbiologists, and clinical laboratories will want to keep an eye on the spread of the Oropouche virus. (Photo copyright: Boston University.)
Risks to Pregnant Women, Seniors
Research published in The Lancet Infectious Diseases estimates up to five million people in the Americas are at risk of exposure to the Oropouche virus. The authors also pointed out that cases in Brazil swelled from 261 between the years 2015 to 2022 to 7,497 by August 2024.
About 60% of people infected with Oropouche have symptoms such as fever, chills, headache, muscle aches, and joint pains, according to the CDC Health Advisory, which added that the symptoms generally appear three to 10 days after exposure.
Those with the highest risk of complications from the disease, according to the CDC, include pregnant women, those over age 65, and people with medical conditions such as:
“The geographic range expansion, in conjunction with the identification of vertical transmission and reports of deaths, has raised concerns about the broader threat this virus represents in the Americas,” an additional paper in Emerging Infectious Diseases noted.
“Healthcare providers should be aware of the risk of vertical transmission and possible adverse impacts on the fetus including fetal death or congenital abnormalities,” CDC said in an Oropouche Clinical Overview statement.
“There have been a few cases of maternal to fetal transmission, and there are four cases of congenital Oropouche infections that have been described—all of which led to microcephaly, which is a small head size,” David Hamer, MD, infectious disease specialist and professor global health, Boston University School of Public Health, told NPR.
Diagnostic Testing at Public Labs
Clinical laboratories and physicians should coordinate with state or local health departments for Oropouche virus testing and reporting.
People should consider Oropouche virus testing if they have traveled to an area with documented or suspected cases, have symptoms including fever and headache, and have tested negative for other diseases, especially dengue, according to CDC.
Taking Precautions after Sex
“This [possibility of sexual transmission] brought up more questions than answers,” Hamer told NPR, adding, “we know now is that sexual transmission could happen.”
Though no documented cases of sexual transmission have been recorded, the CDC nevertheless published updated interim guidance, “recommending that male travelers who develop Oropouche symptoms after visiting areas with Level 1 or 2 Travel Health notices for Oropouche to ‘consider using condoms or not having sex for at least 6 weeks’ from the start of their symptoms,” NPR reported.
“Because stillbirths, birth defects, and severe complications and deaths in adults have been reported, CDC is providing interim recommendations on preventing possible sexual transmission based on what we know now,” the CDC stated.
Clinical laboratory leaders working with infectious disease colleagues can help educate physicians and the community about the Oropouche virus and the need to prevent bites from midges and mosquitoes by using, for example, Environmental Protection Agency (EPA) registered insect repellant.
Diagnostics professionals will want to stay abreast of developing Oropouche cases as well as changes to or expansion of clinical laboratory testing and reported guidance.
Given the large number of mutations found in the SARS-CoV-2 Omicron variant, experts in South Africa speculate it likely evolved in someone with a compromised immune system
As the SARS-CoV-2 Omicron variant spreads around the United States and the rest of the world, infectious disease experts in South Africa have been investigating how the variant developed so many mutations. One hypothesis is that it evolved over time in the body of an immunosuppressed person, such as a cancer patient, transplant recipient, or someone with uncontrolled human immunodeficiency virus infection (HIV).
One interesting facet in the story of how the Omicron variant was being tracked as it emerged in South Africa is the role of several medical laboratories in the country that reported genetic sequences associated with Omicron. This allowed researchers in South Africa to more quickly identify the growing range of mutations found in different samples of the Omicron virus.
“Normally your immune system would kick a virus out fairly quickly, if fully functional,” Linda-Gail Bekker, PhD, of the Desmond Tutu Health Foundation (formerly the Desmond Tutu HIV Foundation) in Cape Town, South Africa, told the BBC.
“In someone where immunity is suppressed, then we see virus persisting,” she added. “And it doesn’t just sit around, it replicates. And as it replicates it undergoes potential mutations. And in somebody where immunity is suppressed that virus may be able to continue for many months—mutating as it goes.”
Multiple factors can suppress the immune system, experts say, but some are pointing to HIV as a possible culprit given the likelihood that the variant emerged in sub-Saharan Africa, which has a high population of people living with HIV.
Li “was among the first to detail extensive coronavirus mutations in an immunosuppressed patient,” the LA Times reported. “Under attack by HIV, their T cells are not providing vital support that the immune system’s B cells need to clear an infection.”
Linda-Gail Bekker, PhD (above), of the Desmond Tutu Health Foundation cautions that these findings should not further stigmatize people living with HIV. “It’s important to stress that people who are on anti-retroviral medication—that does restore their immunity,” she told the BBC. (Photo copyright: Test Positive Aware Network.)
Omicron Spreads Rapidly in the US
Genomics surveillance Data from the CDC’s SARS-CoV-2 Tracking system indicates that on Dec. 11, 2021, Omicron accounted for about 7% of the SARS-CoV-2 variants in circulation, the agency reported. But by Dec. 25, the number had jumped to nearly 60%. The data is based on sequencing of SARS-CoV-2 by the agency as well as commercial clinical laboratories and academic laboratories.
Experts have pointed to several likely factors behind the variant’s high rate of transmission. The biggest factor, NPR reported, appears to be the large number of mutations on the spike protein, which the virus uses to attach to human cells. This gives the virus an advantage in evading the body’s immune system, even in people who have been vaccinated.
“The playing field for the virus right now is quite different than it was in the early days,” Joshua Schiffer, MD, of the Fred Hutchinson Cancer Research Center, told NPR. “The majority of variants we’ve seen to date couldn’t survive in this immune environment.”
One study from Norway cited by NPR suggests that Omicron has a shorter incubation period than other variants, which would increase the transmission rate. And researchers have found that it multiplies more rapidly than the Delta variant in the upper respiratory tract, which could facilitate spread when people exhale.
Using Genomics Testing to Determine How Omicron Evolved
But how did the Omicron variant accumulate so many mutations? In a story for The Atlantic, virologist Jesse Bloom, PhD, Professor, Basic Sciences Division, at the Fred Hutchinson Cancer Research Center in Seattle, described Omicron as “a huge jump in evolution,” one that researchers expected to happen “over the span of four or five years.”
Hence the speculation that it evolved in an immunosuppressed person, perhaps due to HIV, though that’s not the only theory. Another is “that the virus infected animals of some kind, acquired lots of mutations as it spread among them, and then jumped back to people—a phenomenon known as reverse zoonosis,” New Scientist reported.
Still, experts are pointing to emergence in someone with a weakened immune system as the most likely cause. One of them, the L.A. Times reported, is Tulio de Oliveira, PhD, Affiliate Professor in the Department of Global Health at the University of Washington. Oliveira leads the Centre for Epidemic Response and Innovation at Stellenbosch University in South Africa, as well as the nation’s Network for Genomic Surveillance.
The Network for Genomic Surveillance, he told The New Yorker, consists of multiple facilities around the country. Team members noticed what he described as a “small uptick” in COVID cases in Gauteng, so on Nov. 19 they decided to step up genomic surveillance in the province. One private clinical laboratory in the network submitted “six genomes of a very mutated virus,” he said. “And, when we looked at the genomes, we got quite worried because they discovered a failure of one of the probes in the PCR testing.”
Looking at national data, the scientists saw that the same failure was on the rise in PCR (Polymerase chain reaction) tests, prompting a request for samples from other medical laboratories. “We got over a hundred samples from over thirty clinics in Gauteng, and we started genotyping, and we analyzed the mutation of the virus,” he told The New Yorker. “We linked all the data with the PCR dropout, the increase of cases in South Africa and of the positivity rate, and then we began to see it might be a very suddenly emerging variant.”
Oliveira’s team first reported the emergence of the new variant to the World Health Organization, on Nov. 24. Two days later, the WHO issued a statement that named the newly classified Omicron variant (B.1.1.529) a “SARS-CoV-2 Variant of Concern.”
Microbiologists and clinical laboratory specialists in the US should keep close watch on Omicron research coming out of South Africa. Fortunately, scientists today have tools to understand the genetic makeup of viruses that did not exist at the time of SARS 2003, Swine flu 2008/9, MERS 2013.
