A case report found more than ten times as much viral RNA in an American healthcare worker’s throat as in his blood. The unusual distribution may influence future testing and infection-control research, although laboratories did not recover live virus from the samples.
Could the throat contain unexpectedly high concentrations of Bundibugyo Ebola virus during acute illness?
A case report involving a 39-year-old American healthcare worker found that his throat contained more than ten times as much Bundibugyo virus RNA as his blood plasma on the fifth day of illness.
The finding is important because Ebola disease is commonly monitored using blood samples, while less is known about how the rare Bundibugyo virus is distributed across different parts of the body.
However, the measurements detected viral genetic material which are not necessarily infectious virus. Laboratories were unable to grow live virus from the available throat, blood or semen samples, and the report involved only one patient. The result therefore does not prove that throat secretions were more infectious or that Bundibugyo Ebola spreads through the air (1✔ ✔Trusted Source
A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine
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Throat Viral RNA Exceeded Plasma Levels Tenfold
On the fifth day after symptoms began, researchers measured approximately:
- 90 million viral RNA copies per milliliter in an oropharyngeal or throat swab
- 7 million viral RNA copies per milliliter in blood plasma
The throat concentration was therefore more than ten times the plasma concentration.
Researchers described the comparatively high viral RNA levels in oropharyngeal samples as particularly notable because the distribution differed from patterns previously reported in Ebola disease.
The result may encourage further investigation of throat sampling, airway precautions and exposure risks during procedures involving the mouth or upper respiratory tract.
Nevertheless, a PCR measurement cannot determine by itself whether intact, replication-capable virus is present. PCR tests can remain positive because they detect fragments of viral RNA even when infectious virus cannot be recovered (1✔ ✔Trusted Source
A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine
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The Patient Was Infected While Working in Congo
The previously healthy healthcare worker acquired the infection while working in Ituri Province in the Democratic Republic of the Congo.
Nine days before his symptoms began, he performed an ultrasound examination. The following day, he participated in two medical procedures involving patients who later died after developing severe illness.
He reported using standard personal protective equipment and could not identify a specific incident involving an obvious high-risk exposure.
This illustrates one of the difficulties healthcare workers face during an Ebola outbreak. Patients may initially present with symptoms resembling other infections or medical emergencies, and exposure may occur before Ebola disease is suspected.
Several other healthcare workers and caregivers associated with the clinical cluster reportedly developed hemorrhagic illness and died (1✔ ✔Trusted Source
A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine
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Symptoms Progressed Rapidly During the First Three Days
The man initially developed severe muscle pain and malaise and voluntarily isolated himself when symptoms began.
His condition subsequently progressed to include:
- A fever of 38.9°C despite acetaminophen
- Abdominal pain
- Vomiting
- Confusion
- Dizziness and other symptoms when standing
A broad PCR test for Ebola virus RNA in plasma produced a positive result on the second day of illness.
By the third day, his worsening gastrointestinal and neurological symptoms prompted preparations for experimental treatment and medical evacuation to Germany (1✔ ✔Trusted Source
A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine
Experimental Antibodies and Remdesivir Were Administered
There is currently no licensed vaccine or approved virus-specific treatment for disease caused by the Bundibugyo virus.
The healthcare worker had received the rVSV-ZEBOV Ebola vaccine approximately 41 months earlier. However, that vaccine was developed to protect against the Zaire Ebola virus species and is not expected to provide reliable protection against the antigenically distinct Bundibugyo virus.
On the fourth day of illness, the patient received MBP134 at a dose of 50 mg per kilogram. MBP134 is an investigational combination of two broadly neutralizing monoclonal antibodies designed to recognize multiple Ebola viruses.
Access was arranged under an emergency investigational authorization from the US Food and Drug Administration.
He also received a 200 mg loading dose of remdesivir off-label. Remdesivir is an antiviral medicine that interferes with viral RNA replication, but it has not been established as an effective treatment for Bundibugyo virus disease.
The patient arrived at Charité–Universitätsmedizin Berlin on the fifth day of illness and was admitted to a specialised high-level isolation unit. Initial testing showed low platelet and lymphocyte counts and elevated liver enzymes (1✔ ✔Trusted Source
A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine
Viral RNA Became Undetectable in Most Samples by Day 13
Viral RNA concentrations declined during treatment and supportive care.
By the 13th day after symptoms began, viral RNA had fallen below the tests’ detection limits in:
- Blood plasma
- Throat swabs
- Urine
- Stool
Semen remained positive for viral RNA on day 20, when approximately 2,500 copies per millilitre were detected. It tested negative by day 25.
Persistence in semen has previously been observed in survivors of Ebola disease and is one reason sexual-health guidance and follow-up testing may be recommended after recovery.
Three specialized laboratories attempted to culture live virus from the throat, plasma and semen samples but did not recover replication-capable virus.
However, samples collected before the experimental antibody treatment were not available for comparison. Researchers therefore could not determine whether the negative cultures reflected the treatment, the timing of sample collection or another factor (1✔ ✔Trusted Source
A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine
The Patient Recovered, but Treatment Effectiveness Is Uncertain
The patient became free of fever without antipyretic medicine from the seventh day of illness. His clinical condition and laboratory abnormalities subsequently improved, and he was discharged 22 days after symptoms began.
Researchers also found evidence that his own immune system produced antibodies against the virus despite the administration of monoclonal antibodies.
Virus-specific immunoglobulin M and immunoglobulin A antibodies were detected, while antibodies against a viral protein not targeted by MBP134 increased between days five and six. This indicated that the patient had developed an endogenous immune response rather than relying entirely on the infused antibodies.
The recovery is encouraging, but one case cannot establish that MBP134, remdesivir or their combination caused the improvement.
High Throat RNA Does Not Mean Ebola Is Airborne
Ebola disease spreads through direct contact with blood or other body fluids from a person who is ill or has died from the infection. Transmission may also occur through contaminated needles, medical equipment or other materials.
The disease is not considered to spread through routine airborne transmission.
A high concentration of viral RNA in a throat sample does not change that established understanding. It also does not prove that coughing or breathing produced infectious airborne particles.
However, throat secretions can come into contact with healthcare workers during airway management, endoscopy, oral examination, suctioning, intubation or other procedures.
If similar throat findings are documented in additional patients, researchers may need to investigate whether certain procedures require modified sampling protocols or additional protection against direct exposure to oral secretions.
For now, the finding should be interpreted as a laboratory observation that generates an important research question—not as evidence of a new transmission route (2✔ ✔Trusted Source
Ebola Disease Outbreak in the Democratic Republic of the Congo and Uganda – US Centers for Disease Control and Prevention
Bundibugyo Virus Causes a Rare Form of Ebola Disease
Bundibugyo virus has caused only three recorded outbreaks since it was first identified in Uganda in 2007.
Symptoms can appear two to 21 days after exposure and may include fever, fatigue, muscle pain, vomiting, diarrhoea, abdominal pain and unexplained bleeding.
People are not considered contagious before symptoms begin. Once illness develops, the virus can spread through direct contact with infected body fluids or contaminated materials. Early diagnosis, isolation, supportive care, contact tracing and strict infection control remain essential.
Congo Outbreak Has Become the Country’s Largest
The Democratic Republic of the Congo confirmed the outbreak in Ituri Province on 15 May 2026. The World Health Organization declared it a public health emergency of international concern two days later.
WHO has described the event as the largest Ebola outbreak recorded in the country and one that expanded more quickly than previous Congolese outbreaks.
According to the European Centre for Disease Prevention and Control, the Democratic Republic of the Congo had reported 5,713 confirmed cases and 2,744 deaths as of 25 August 2026.
Ituri Province accounted for 4,750 cases and 2,133 deaths. Infections had been recorded in 58 health zones across six provinces.
Uganda also reported travel-linked cases but declared its outbreak over after completing the required monitoring period without additional infections.
Case totals continue to change as surveillance, testing and retrospective investigations identify additional patients .
Risk to the American Public Remains Low
The CDC considers the risk of Bundibugyo Ebola spreading in the United States to be low, with no outbreak-related cases confirmed in the country.
Clinicians should nevertheless check for recent travel to affected regions or contact with a suspected patient when evaluating compatible symptoms. Suspected cases should be isolated promptly and reported to public-health authorities before testing.
The American patient was transported and treated in Germany under specialised containment procedures. His medical evacuation does not indicate community transmission in Germany or the United States. (2✔ ✔Trusted Source
Ebola Disease Outbreak in the Democratic Republic of the Congo and Uganda – US Centers for Disease Control and Prevention
The Case Identifies Questions That Larger Studies Must Answer
The unexpectedly high throat viral RNA raises questions about viral shedding, testing, procedure-related exposure and the effectiveness of MBP134 and remdesivir.
However, this was a single case. The finding does not suggest a new transmission route, but indicates that Bundibugyo Ebola may behave differently across parts of the body.
References:
- A Case of Bundibugyo Virus Disease Treated With Monoclonal Antibodies and Remdesivir – Nature Medicine (https://doi.org/10.1038/s41591-026-04663-5)
- Ebola Disease Outbreak in the Democratic Republic of the Congo and Uganda – US Centers for Disease Control and Prevention (https://www.cdc.gov/han/php/notices/han00530.html)
Source-Medindia