Marburg virus disease outbreak in Kween District Uganda, 2017: Epidemiological and laboratory findings

Introduction In October 2017, a blood sample from a resident of Kween District, Eastern Uganda, tested positive for Marburg virus. Within 24 hour of confirmation, a rapid outbreak response was initiated. Here, we present results of epidemiological and laboratory investigations. Methods A district task force was activated consisting of specialised teams to conduct case finding, case management and isolation, contact listing and follow up, sample collection and testing, and community engagement. An ecological investigation was also carried out to identify the potential source of infection. Virus isolation and Next Generation sequencing were performed to identify the strain of Marburg virus. Results Seventy individuals (34 MVD suspected cases and 36 close contacts of confirmed cases) were epidemiologically investigated, with blood samples tested for MVD. Only four cases met the MVD case definition; one was categorized as a probable case while the other three were confirmed cases. A total of 299 contacts were identified; during follow- up, two were confirmed as MVD. Of the four confirmed and probable MVD cases, three died, yielding a case fatality rate of 75%. All four cases belonged to a single family and 50% (2/4) of the MVD cases were female. All confirmed cases had clinical symptoms of fever, vomiting, abdominal pain and bleeding from body orifices. Viral sequences indicated that the Marburg virus strain responsible for this outbreak was closely related to virus strains previously shown to be circulating in Uganda. Conclusion This outbreak of MVD occurred as a family cluster with no additional transmission outside of the four related cases. Rapid case detection, prompt laboratory testing at the Uganda National VHF Reference Laboratory and presence of pre-trained, well-prepared national and district rapid response teams facilitated the containment and control of this outbreak within one month, preventing nationwide and global transmission of the disease.
Author summary Marburg virus disease (MVD) is caused by the virus that belongs to the same family as that of Ebola Virus disease. The disease is characterized by severe clinical symptoms such as high fever, diarrhoea and vomiting, and severe bleeding from most body openings. On average, 54% of the people who get infected with Marburg virus die from it [1]. In October 2017, Uganda reported an outbreak of MVD in the eastern district of Kween that borders Kenya in the Mount Elgon plains. This was the first time MVD was being detected in this part of the country since previous MVD outbreaks had been reported in the western part of Uganda. The Ministry of Health together with partners instituted rapid outbreak response for control. Investigations revealed a cluster of one family involving four cases whereby only one survived. The outbreak was traced back into bat caves in Kween district. Rock salt mining in the cave led to a spill-over of the virus into the human population with the subsequent person-to-person transmission. Through contact tracing and isolation of the infected people among other approaches, the outbreak was brought under control as explained in this article.