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25 October 2024

Situation at a glance

As of 24 October 2024, a total of 64 Marburg virus disease cases, including 15 deaths (case fatality ratio (CFR) 23.4%), have been reported in Rwanda. Among the initial 62 confirmed cases with available data, 70% were males, and 48% were aged between 30 to 39 years. The highest number of new confirmed cases were reported in the first two epidemiological weeks of the outbreak with 26 cases reported in epidemiological week 39 (23 to 29 September 2024) and 23 cases in week 40 (30 September to 6 October). This was followed by a sharp decline in weeks 41 and 42, with 12 and one case reported respectively. Contact tracing is ongoing, with 1146 contacts under follow-up as of 20 October 2024. Based on available updates from the outbreak investigation, the index case was a male between 20 and 30 years old with a history of exposure to bats in a cave.

Description of the situation

 

Since the last Disease Outbreak News on this event was published on 18 October 2024, two additional laboratory-confirmed cases of Marburg virus disease (MVD) were reported in Rwanda on 23 and 24 October. The new cases include a healthcare worker who had been treating MVD cases since the start of the outbreak and a case linked to the site where the index case was exposed. Both cases are currently in isolation and receiving treatment. As of 24 October 2024, a total of 64 confirmed cases, including 15 deaths (CFR: 23.4%), have been reported. Excluding the recently confirmed cases, 70% of the 62 initially confirmed cases were among males, and 48% were among adults between 30 and 39 years of age. Health workers from two health facilities in Kigali account for over 82% of confirmed cases. Most of the cases have been reported from the three districts in Kigali city.

The highest number of new confirmed cases were reported in the first two epidemiological weeks of the outbreak with 26 cases reported in the epidemiological week 39 (23 to 29 September 2024) and 23 cases in week 40 (30 September to 6 October). This was followed by a sharp decline in epi weeks 41 (7 to 13 October) and 42 (14 to 20 October), with 12 and one cases reported respectively.

Since the declaration of the outbreak by the Government of Rwanda on 27 September and as of 23 October, 46 confirmed cases have recovered, and three cases are under care at the designated Marburg treatment center. The 62 confirmed cases reported since the start of the outbreak have been part of one major cluster with three branches. As of 24 October 2024, a total of 5074 tests for Marburg virus have been conducted, with approximately 100-300 samples being tested daily at the Rwanda Biomedical Center.

Contact tracing is ongoing, with 1146 contacts under follow-up as of 20 October 2024.

WHO continues to support the Government of Rwanda. Enhanced surveillance, contact tracing and infection prevention and control measures must be maintained until the outbreak is declared over.

Based on available updates from the outbreak investigation, the index case was a male between 20 and 30 years old with a history of exposure to bats in a cave. Preliminary phylogenetic analyses indicate a close evolutionary relationship to a viral sequence from Orthomarburgvirus marburgense (Marburg virus, MARV) that was observed in the MVD outbreak in East Africa in 2014.1Figure 1. MVD cases by week of reporting in Rwanda, as of 24 October 2024, (n=64)

MVD Epi curve

* The epidemiological week 43 is not complete as it will end on 27 October 2024.

 

Epidemiology

MVD is a highly virulent disease that can cause haemorrhagic fever and is clinically similar to Ebola virus disease. Marburg and Ebola viruses are both members of the Filoviridae family (filovirus). People are infected with Marburg virus when they come into close contact with Rousettus bats, a type of fruit bat, that can carry the Marburg virus and are often found in mines or caves. Marburg virus then spreads between people via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids. Health workers have previously been infected while treating patients with suspected or confirmed MVD. Burial ceremonies that involve direct contact with the body of the deceased can also contribute to the transmission of Marburg virus.

The incubation period varies from two to 21 days. Illness caused by Marburg virus begins abruptly, with high fever, severe headache and severe malaise. Severe watery diarrhoea, abdominal pain and cramping, nausea and vomiting can begin on the third day. Although not all cases present with haemorrhagic signs, severe haemorrhagic manifestations may appear between five and seven days from symptoms onset, and fatal cases usually have some form of bleeding, often from multiple areas. In fatal cases, death occurs most often between eight and nine days after symptom onset, usually preceded by severe blood loss and shock. There is currently no approved treatment or vaccine for MVD. Some candidate vaccines and therapeutics are currently under investigation.

Seventeen outbreaks of MVD have previously been reported globally. The most recent outbreaks were reported in Equatorial Guinea and the United Republic of Tanzania between February and June 2023. Additional countries that previously reported outbreaks of MVD in the African Region include Angola, the Democratic Republic of the Congo, Ghana, Guinea, Kenya, South Africa, and Uganda.

Public health response

  • The Government of Rwanda is coordinating the response with support from WHO and partners.
  • A surge team from WHO was deployed to support the in-country response across the functions of incident management, epidemiology, health operations, case management, infection prevention and control, health logistics, therapeutics and vaccines research, and partner coordination.
  • On 19-20 October, WHO Director-General Dr Tedros Adhanom Ghebreyesus visited Kigali, where he met with the national authorities and WHO staff taking part in the national response.
  • WHO is continuously engaged with its viral hemorrhagic fever collaborating centers and other reference laboratories and partners to support Rwanda in assessing laboratory test performance.
  •  WHO is supporting the Government in the establishment of a programme for recovered patients, by sharing technical guidance and protocols for the establishment of a national programme and by supporting Rwanda Ministry of Health (MOH) implementation effort.
  • WHO, the Government of Rwanda, and partners have launched Marburg therapeutics clinical trials, which is currently enrolling patients.
  • WHO and partners supported MOH in developing and finalising the national Infection Prevention and Control (IPC) operational guidance for MVD adapted from WHO IPC guideline. This operational guidance together with IPC standard operating procedures is being rapidly disseminated to all health facilities.
  • WHO supported MOH in the enhancing of IPC measures in the isolation sites.
  • WHO has provided technical advice to public health authorities in Rwanda and at-risk countries on the implementation of evidence-informed and risk-based health measures; the strengthening of detection, reporting and management capacities at points of entry and across borders; and travel advice.
  • WHO has published interim guidance on the Considerations for border health and points of entry for filovirus disease outbreaks, which applies to but is not limited to the current MVD outbreak in Rwanda.
  • WHO has also published a statement advising against any travel restrictions and against any trade restrictions with Rwanda in the context of the ongoing MVD outbreak.
  • WHO is providing support in surrounding countries to assess the readiness of healthcare facilities, points of entry and border communities within surrounding countries and specifically risk mapping for areas bordering Rwanda.
  • WHO is supporting the MVD treatment center with direct support from clinical experts in infectious disease, ICU and nursing as well as health logistics and WASH.

WHO risk assessment

Marburg virus disease (MVD) is caused by the same family of viruses (Filoviridae) that causes Ebola virus disease. MVD is an epidemic-prone disease associated with high CFR (24-88%). In the early course of the disease, MVD is challenging to distinguish from other infectious diseases such as malaria, typhoid fever, shigellosis, meningitis and other viral haemorrhagic fevers. Epidemiologic features can help differentiate between viral hemorrhagic fevers (including history of exposure to bats, caves, or mining) and laboratory testing is important to confirm the diagnosis.

With 64 confirmed cases reported, this is the third largest MVD outbreak reported to date, with 82% of confirmed cases reported among healthcare workers. Healthcare-associated infections (also known as nosocomial infections) of this disease can lead to further spread if not controlled early. The importance of screening all persons entering health facilities as well as inpatient surveillance for prompt identification, isolation, and notification cannot be overemphasized. This is in addition to the importance of contact identification and listing and daily follow-up of all contacts.

Based on the outbreak investigation which included record review in health facilities, review of epidemiological data, serology and genomic sequencing, as well as environmental and animal testing, the source of the outbreak is reported to be of zoonotic origin, linked to exposure in a cave inhabited by fruit bats. However, the dates of symptom onset of cases is still unknown to WHO.

On 30 September, WHO assessed the risk of this outbreak as very high at the national level, high at the regional level, and low at the global level. However, based on the evolution of the outbreak and ongoing investigations, this risk assessment may be revised. MVD is not easily transmissible (i.e. in most instances it requires contact with the body fluids of a sick patient presenting with symptoms or with surfaces contaminated with these fluids). In addition, there are ongoing public health measures in place, including active surveillance in facilities and communities, testing suspected cases, isolation and treatment of cases and contact tracing.

WHO advice

MVD outbreak control relies on using a range of interventions, including prompt isolation and case management; surveillance including active case search, case investigation and contact tracing; a laboratory service; infection prevention and control, including prompt safe and dignified burial; and social mobilization – community engagement is key to successfully controlling MVD outbreaks. Raising awareness of risk factors for Marburg virus infection and protective measures that individuals can take is an effective way to reduce human transmission. WHO advises the following risk reduction measures as an effective way to reduce MVD transmission in healthcare facilities and in communities:

  • To reduce human infections and deaths, it is essential to raise community awareness about the risk factors for Marburg virus infection particularly of human-to-human transmission, and the protective measures individuals can take to minimize exposure to the virus.  This includes encouraging anyone with symptoms to seek immediate care at a health facility or designated treatment center to lower the risk of community transmission and improve their chances for recovery.
  • Reducing the risk of bat-to-human transmission arising from prolonged exposure to mines or caves inhabited by fruit bat colonies. People visiting or working in mines or caves inhabited by fruit bat colonies should wear gloves and other appropriate protective clothing (including masks).
  • Surveillance activities, including the wide dissemination of the MVD case definition, should be strengthened in all affected districts, including contact tracing and active case finding.
  • Patient-care activities should be undertaken in a clean and hygienic environment that facilitates practices related to the prevention and control of health-care-associated infections (HAIs) as outlined in Essential environmental health standards in health care. Safe water, adequate sanitation and hygiene infrastructure and services should be provided in healthcare facilities. For details on recommendations and improvement, follow the WASH FIT implementation Package
  • A comprehensive strategy to manage deceased individuals in communities should be implemented in communities. Safe and dignified burials should be carried out, with strong engagement communities.
  • Rapid qualitative assessments should be implemented to collect socio-behavioural data, which can then be utilized to guide the response.
  • Results of the phone Knowledge, Attitude and Practices (KAP) survey and other surveys should be integrated into the response strategy and interventions.
  • Timely laboratory testing of all suspected cases needs to be maintained and supported with a reliable sample transportation system.
  • Border health readiness and response capacities should be strengthened at points of entry and in communities bordering areas reporting MVD cases and onboard conveyances, and public health advice should be provided to travellers in line with WHO’s interim guidance on considerations for border health and points of entry for filovirus disease outbreaks.
  • WHO encourages all countries to send the first samples that tested positive for Marburg virus and a subset of negative samples to a WHO Collaborating Centre or a regional reference laboratory for inter-laboratory comparison.
  • WHO recommends that clinical data from suspected and confirmed Marburg virus disease cases be systematically collected to improve the limited understanding of the clinical course and direct causes and risk factors for poor outcomes. This can be done by contributing anonymized data to the WHO Global Clinical Platform for viral haemorrhagic fevers.
  • WHO advises that all patients with MVD receive holistic care including optimized supportive care including critical care and mental health services in a treatment center designed for optimal patient care and patient centered experience with biosecurity measures such as unidirectional patient and staff flow and WASH services in place.

Based on the current risk assessment, WHO advises against any travel restrictions or any trade restrictions with Rwanda. For further information, please see WHO advice for international traffic in relation to the Marburg virus disease outbreak in Rwanda.

Further information

[1] Biedenkopf, N., Bukreyev, A., Chandran, K., Di Paola, N., Formenty, P. B. H., Griffiths, A., Hume, A. J., Mühlberger, E., Netesov, S. V., Palacios, G., Pawęska, J. T., Smither, S., Takada, A., Wahl, V., & Kuhn, J. H. (2024). ICTV Virus Taxonomy Profile: Filoviridae 2024, Journal of General Virology 105, 001955

Citable reference: World Health Organization (25 October 2024). Disease Outbreak News; Marburg virus disease in Rwanda. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON541

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