UKHSA Confirms 3rd Lassa Fever Case (Deceased) - ECDC Risk Assessment

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Two days ago, in UKHSA Reports 2 (Travel Related) Lassa Fever Cases - 1 Additional Suspected, we looked at the initial report of a `travel related' family cluster of Lassa fever cases reported in the UK. 

Very few details, however, were offered by the UKHSA. 

Lassa fever is a Viral Hemorrhagic Fever (VHF) which is endemic in parts of West Africa (see map above), and is commonly carried by multimammate rats. a local rodent that often likes to enter human dwellings. 

Exposure is typically through the urine or dried feces of infected rodents, and roughly 80% who are infected only experience mild symptoms. The incubation period runs from 10 days to 3 weeks, and the overall mortality rate is believed to be in the 1%-2% range, although it runs much higher (15%-20%) among those sick enough to be hospitalized.

Like many other hemorrhagic fevers, person-to-person transmission may occur with exposure to the blood, tissue, secretions, or excretions of an individual (cite CDC Lassa Transmission).

Late yesterday the UK confirmed the 3rd case (see below), and also announced that patient has died. They haven't divulged, however, whether all three cases traveled abroad or if one or more are locally acquired secondary cases, which country was visited, or their travel itinerary. 

Lassa fever cases identified in England, following travel to West Africa

Latest updates on cases of Lassa fever identified in England.
From:UK Health Security Agency Published 11 February 2022  

Latest update

The UK Health Security Agency (UKHSA) can confirm that the probable case of Lassa fever under investigation is now confirmed, bringing the total number of cases to 3. Sadly, this individual has died.

We are contacting the individuals who have had close contact with the cases prior to confirmation of their infection, to provide appropriate assessment, support and advice. The risk to the general public remains very low.

A Bedfordshire Hospitals NHS Foundation Trust spokesperson said:

We confirm the sad death of a patient at our trust, who had confirmed Lassa fever. We send our deepest condolences to their family at this difficult time.

We will continue to support the patient’s family and our staff and are working closely with colleagues from UKHSA to undertake a robust contact tracing exercise.

Released before the above announcement, we also have the following ECDC CDTR report, and risk assessment, on this incident.

New! Lassa fever - United Kingdom ex. West Africa - 2022 

Opening date: 10 February 2022 

Latest update: 11 February 2022 

Epidemiological summary On 9 February 2022, the UK Health Security Agency reported two confirmed cases and one probable case of Lassa fever in East England. The cases are related to recent travel to West Africa and all the cases are from the same household. Among the confirmed cases, one has recovered while the other is still hospitalised in London; the probable case is receiving healthcare in a hospital in Bedfordshire, England. 

According to the UK Health Security Agency, there have been eight cases of Lassa fever imported to the UK since 1980, with the last two cases being reported in 2009. 

Source: UK health security agency 

ECDC assessment

The few Lassa fever cases detected in the EU/EEA to date have all been imported from endemic areas, with the exception of one secondary case reported in Germany in 2016. 

The likelihood of infection for EU/EEA citizens in relation to this event in the UK is negligible. However, while the likelihood of infection for EU/EEA citizens travelling to West Africa remains very low, these travellers should be informed of the risk of exposure to Lassa fever virus, particularly in areas experiencing ongoing outbreaks. Travellers should avoid exposure to rodents and consumption of foods and drinks potentially contaminated by rodent droppings, and to people experiencing haemorrhagic fever symptoms. In order to prevent human to human transmission, unprotected contacts with patients' blood and body fluids should be avoided as well as exposure to possible contaminated surfaces or materials.

Public health actors should remain vigilant regarding the possibility of imported Lassa fever cases and ensure an early diagnosis to avoid secondary transmission. 

ECDC conducted a ³Rapid risk assessment: cases of Lassa fever in the Netherlands ex Sierra Leone´in 2019, the conclusions of which remain valid. 

Actions 

ECDC will continue to monitor the ongoing situation and will report again should relevant epidemiological updates become available.