Assessing #Ebola virus circulation in the Tshuapa province (#DRC): A #OneHealth #investigation of wildlife and #human interactions

 

Abstract

The wildlife reservoir and spillover mechanisms of Ebola virus remain elusive despite extensive research efforts in endemic areas. This study employed a One Health approach to examine the virus’ circulation in wildlife and the associated human exposure risks in the Tshuapa province of the Democratic Republic of the Congo. We screened 1049 samples from 919 animals, predominantly small mammals, collected in 2021, and 380 samples from inhabitants of Inkanamongo village, the site of an Ebola virus disease outbreak in 2014. These samples were screened for evidence of current (RNA) or past (IgG antibodies) Ebola virus infections. We also conducted interviews with 167 individuals in the surrounding districts to assess their interactions with wildlife. While no Ebola virus RNA was detected in the wildlife samples, anti-orthoebolavirus IgG antibodies were found in 13 bats and 38 rodents. Among the human participants, 120 individuals had IgG antibodies against at least 1 orthoebolavirus antigen, with 12 showing seropositivity for 2 antigens of the same orthoebolavirus, despite not having a prior Ebola disease diagnosis. Furthermore, the majority of respondents reported frequent visits to the forest to hunt a variety of wild animals, particularly ungulates and rodents, which could account for occasional viral spillovers. The absence of active Ebola virus circulation in wildlife may reflect seasonal patterns in reservoir ecology, as those observed in bats. Similarly, seasonal human activities, such as hunting and foraging, may result in periodic exposure risks. These findings highlight the importance of continuous, multidisciplinary surveillance to monitor changes in seasonal spillover risks.

Author summary

Since its discovery in 1976 in the Democratic Republic of Congo (DRC), Ebola virus (EBOV) has caused more than 20 outbreaks in humans, with fatality rates as high as 90%. While the virus is believed to have an animal origin, naturalist reservoir and the mechanisms of transmission to humans remain poorly understood. Gaining insight into which species may harbour the virus and how transmission occurs is essential to predict and prevent future outbreaks. In this study, we investigate EBOV exposure in wildlife and humans in a region of the DRC with a documented history of outbreaks. Although we did not detect active infection in animals, we found serological evidence of prior exposure in several bat and rodent species, as well as among local residents. Interviews with community members revealed frequent contact with wildlife through hunting and handling, practices that could elevate the risk of animal-to-human transmission. These findings offer new clues about possible EBOV reservoirs and highlight the role of human behaviours in facilitating facilitate spillover events. Our results underscore the need for continued, integrated surveillance to improve understanding of Ebola virus ecology and to help reduce the risk of future Ebola outbreaks in endemic regions.

Source: 

Link: https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1013628

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RAPID #RISK #ASSESSMENT: #EBOLA VIRUS DISEASE, DRC (#WHO, September 19 '25)

 

{Summary}

Overall risk and confidence

Overall risk

-- National: High 

-- Regional: Moderate   

-- Global: Low   

Confidence in available information 

-- National: Moderate

-- Regional: Moderate

-- Global: Moderate

Risk statement

On 1 September 2025, WHO received an alert from the Ministry of Health of the Democratic Republic of the Congo (DRC) regarding suspected cases of Ebola virus disease (EVD) in the Bulape Health Zone, Kasai Province, DRC. 

The first currently known suspected EVD case was admitted to the Bulape General Reference Hospital on 20 August 2025 and reported to have died five days later (25 August 2025).

This is a 34-year-old female patient with a 34-week gestational age who presented with fever, bloody diarrhoea, followed by anal, oral, and nasal haemorrhage, vomiting, and asthenia. 

She reportedly died on 25 August 2025, with a clinical picture of multiple organ failure. 

Two of the contacts of this first case (a midwife and a laboratory technician) also developed similar symptoms and died a few days later.  

As of 4 September 2025, a total of 28 suspected cases, including 15 deaths (case fatality ratio: 54 %) had been reported from the Bulape health zone (Bulape, Bulape COM and Dikolo) and Mweka health zone. 

Among deaths, four are health care workers.  

In addition, 20% of the suspected cases are aged under 15 years. 

Five blood samples and one swab were collected from six suspected cases from the three health areas and arrived today at the National Public Health Laboratory (INRB) in Kinshasa for confirmation testing.

A crisis committee has been activated at the local and provincial levels, risk communication and active surveillance activities are underway, all cases are isolated, Infection Prevention and Control (IPC) measures are being implemented, isolation and contact tracing are underway, and patients are receiving intravenous medications, including ceftriaxone and metronidazole. 

The INRB confirmed Ebola virus (EBOV), Orthoebolavirus zairense species was detected through RTPCR assays, including GeneXpert, on 3 September.    

At national level, the risk is considered high due to:  

• Information gaps on the cases, including the first case, particularly: 

-- the date of symptom onset, 

-- their therapeutic itinerary, 

-- the potential number of contacts within the community, and 

-- epidemiological links between cases does not allow an assessment as to the extent of the outbreak. Similar alerts have been reported from this location/region in the past few months.  

• Most of the cases recorded so far in this health zone live in the Health Areas with a high population density and mobility. This could accelerate disease transmission within the community.  

• The last EVD outbreak in this health zone, Bulape, was in 2007, 18 years later, the capacities required for the response to a potential EVD outbreak may not exist.  

• So far, in addition to Bulape health zone, the epicentre of the outbreak, suspected cases are being reported in the neighbouring district of Mweka showing a potential geographic extension of the outbreak.   

• Bulape has a large market every Friday, attracting people from the surrounding villages. The city of Mweka borders a health district in the province of Kasai-Central (Bena Leka). Furthermore, population movements between Bulape and Tshikapa, the capital city of Kasai province, are frequent as part of trading activities.  Tshikapa city is considered as a regional market hub receiving populations from neighbouring provinces.  

At the regional level the risk is moderate due to the proximity of Bulape to Tshikapa city, the capital city of Kasai province and the Angolan border (approximately 100 to 200 kilometres depending on the nearest border crossing point) as well as population movement between Bulape and Tshikapa then Tshikapa and Angola.  

At the global level, the risk is low. 

(...)

Source: World Health Organization, https://www.who.int/publications/m/item/who-rapid-risk-assessment---ebola-virus-disease--democratic-republic-of-the-congo-v.1

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Heterologous two-dose #Ebola #vaccine regimen in #pregnant women in #Rwanda: a randomized controlled phase 3 trial

 

Abstract

Risk of death for both mother and fetus following Ebola virus infection is extremely high. In this study, healthy women in Rwanda aged ≥18 years were randomized to two-dose Ebola vaccination (Ad26.ZEBOV, MVA-BN-Filo) during pregnancy (group A) or postpartum (group B). Unvaccinated pregnant group B women served as control. This was a parallel, randomized, controlled, open-label, single-center trial to evaluate the safety (primary endpoint—outcomes of interest and serious adverse events (SAEs)) and immunogenicity (secondary endpoint) of the two-dose Ebola vaccination. Among 3,484 women screened, 2,013 were randomized, and 2,012 women and 1,945 infants born alive were descriptively analyzed. Adverse outcomes of interest occurred in women (5.2% in group A and 7.3% in group B) and infants (26.0% in group A and 25.6% in group B). The most common maternal outcome of interest was pathways to preterm birth (3.2% in group A and 3.4% in group B), and the most common infant outcome of interest was small for gestational age (14.3% in group A and 11.8% in group B). Maternal/fetal and neonatal/infant SAE frequencies were comparable between groups (9.8% in group A, 9.0% in group B and 21.9% in group A, 15.9% in group B, respectively). Anti-Ebola virus glycoprotein-specific binding antibody response (secondary endpoint) was sustained in ≥90% of women at 1 year postdose 1. In group A, binding antibodies were detected in cord blood (99%) and infant serum (95%) samples 14 weeks postbirth. The trial met all primary and secondary objectives. Ad26.ZEBOV, MVA-BN-Filo did not raise concerns regarding adverse maternal/fetal or neonatal/infant outcomes, had no unexpected safety issues, and induced binding antibody responses in women and offspring through passive transfer. ClinicalTrials.gov registration: NCT04556526.

Source: Nature Medicine, https://www.nature.com/articles/s41591-025-03932-z

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#Thermal #tolerance and #inactivation of #Ebola virus

{Summary}

HIGHLIGHTS

• The investigation demonstrated a high level of tolerance of EBOV to thermal disinfection.

• A water-bath is recommended and the tubes should be fully submerged during the process.

• The established inactivation guidelines should be followed very strictly.

Dear Editor,

Viruses of the genus Orthoebolavirus cause sporadic outbreaks of severe haemorrhagic fever, with case fatality rates ranging from 25% to 90% (Mahanty and Bray, 2004). Six species of the virus (Orthoebolavirus zairense, sudanense, bundibugyoense, taiense, restonense, and bombaliense) have so far been identified (Biedenkopf et al., 2023). Among these, Orthoebolavirus zairense, commonly known as Ebola virus (EBOV), stands out as the most virulent. Given its high contagiousness and lethality, EBOV must be manipulated under biosafety level 4 (BSL-4) conditions, as stipulated by the National Health Commission of the People's Republic of China's list of human pathogenic microorganisms. Prior to being removed from a BSL-4 laboratory, it is imperative that infectious EBOV undergoes complete inactivation. Here we systematically evaluate viral thermostability under BSL-4 containment conditions, demonstrating EBOV’s marked thermotolerance.

(...)

Source: Virologica Sinica, https://www.sciencedirect.com/science/article/pii/S1995820X25000975

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