WHO: Update & Risk Assessment On Cluster of Community Deaths in Basankusu, Equateur, DRC

  

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Last week WHO AFRO published a report on a DRC Investigation on Cluster of Illness and Community Deaths in Equateur Province, and while the cause remained undetermined, tests for Ebola and Marburg had come back negative. 

As we've seen often over the years, most `mystery' outbreaks turn out to be due to something already known (malnutrition, measles, malaria, meningitis, contaminated food or water, etc.), but every once in a while something more exotic is at work.  

Late yesterday the WHO published the following update, which describes the outbreak as both `localized'  and `declining' - and while the cause has yet to be determined - has set the local public health risk at `moderate', and the national and global risk as `low'.

Due to its length, I've only posted some excerpts.  Follow the link to read the full report. 

Cluster of community deaths in Basankusu, Equateur- Democratic Republic of the Congo
3 March 2025

Situation at a glance

On 9 February 2025, officials in the Democratic Republic of the Congo reported to regional health authorities a cluster of 24 unexplained community deaths in a single village in Ekoto health area, Basankusu health zone, Equateur province. As of 25 February, a total of 53 deaths have been reported, with the last death occurring on 22 February. Deaths have occurred in all age groups, but adolescents and young adults, particularly males, appeared to be disproportionately affected in the initial cluster reported. Disease progression appeared to be fast, with a median time from onset of symptoms to death of one day.

 Given the rapid decline in the incidence of reported deaths, their geographic clustering, the age profile of deaths and the rapid disease progression in the initial cluster, working hypotheses include chemical poisoning or a rapid onset bacterial meningitis cluster, on a background of malaria and other infectious illnesses endemic in the region. The definitive cause of illness remains undetermined, with initial samples testing negative for Ebola and Marburg viruses. Field investigations and additional laboratory testing are ongoing including but not limited to the cerebrospinal fluid testing and the toxicological analysis of environmental samples, including water and other samples to explore chemical causes. Local authorities began surveillance with a broad case definition including any individual with fever and at least one other symptom, to better understand disease patterns. 

A total of 1318 patients had symptoms meeting the working suspected case definition as of 25 February 2025. Approximately 50% of malaria tests performed on these cases tested positive for malaria, the cases identified through this enhanced surveillance therefore likely reflect the various febrile illnesses in the area. With the available information, WHO assesses the local public health risk as moderate, and the national and global public health risk as low.

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WHO risk assessment

Since the initial cluster of deaths was reported on 9 February 2025, there has been an overall downward trend in deaths. The most recent death was reported on 22 February 2025. Current epidemiological information suggests a localized event with a steady decline in incidence, not expanding in time and place. Given the clinical presentation of deaths and the speed from symptom onset to death in this unusual cluster, current differentials include a rapid onset bacterial meningitis cluster or a contamination by a chemical poisoning as key hypotheses in a context of high incidence of other common infectious diseases in the areas, particularly malaria.

Operational challenges related to this event involve the isolation of Basankusu and resulting logistical barriers, as it is located in a forested region, approximately 450 kilometers from the nearest major city of Mbandaka and has poor infrastructure. The remoteness of Basankusu has hindered the timeliness of the initial investigation and response activities and poses challenges to laboratory testing. Samples must be collected, stored, and shipped long distances to a larger city with laboratory testing capacity (either Mbandaka or Kinshasa), introducing delays in diagnosis. Access to care is another key challenge, as the region lacks robust healthcare services, and the region’s poor infrastructure makes travel to neighboring health zones difficult, leading to delays in treatment.

The province faces a severe urban water crisis with only 5% of its urban population having access to drinking water. The water network suffers frequent leaks and has never been rehabilitated. Many households rely on unregulated private water sources such as wells, springs and streams which pose contamination risks.

With ongoing investigations and given that the causative agent of the cluster is not yet determined, there remains a level of risk attributed to the event. As such, the overall public health risk level to the affected communities is assessed as moderate.

At the national level, however, the risk is considered low due to the localized nature of the event and apparent decreasing incidence. Similarly, at the regional and global levels, the risk is low at this time.

         (Continue . . . )