PandemicPreparedness

International SOS is monitoring this situation closely.

Updated 3 December: A Rapid Risk Assessment published by the European Centre for Disease Prevention and Control (ECDC) has provided more information about the 150-plus contacts found to date. Contacts have been identified in Sierra Leone, the Netherlands, the United Kingdom, Germany, Denmark, Uganda and India. The majority of the contacts are Dutch healthcare workers, either those who worked in Sierra Leone or who have been involved in the medical treatment of the two evacuated Doctors once they returned to the Netherlands. One of these doctors remains in treatment at Utrecht Hospital, so further low-risk contacts in hospital staff are being identified. 

Many of the contacts in Sierra Leone have finished their 21-day follow-up monitoring period without incident. This includes people who attended an international surgical training event in Freetown, Sierra Leone, on 11-12 November, with the Dutch doctor who later died.

Updated 28 November: The World Health Organization (WHO) have published a Disease Outbreak News about the confirmed cases and contacts. The source of the outbreak of Lassa Fever originating at Masanga Hospital, Tonkolili district, is believed to be a female patient who was operated on and died on 4 November. A second patient also operated on during 4th November died on 19th November. Both are probable cases as no samples were collected.

A male Dutch doctor who operated on both these women on 4 November began to develop symptoms on 11 November. He attended a surgical training event on 11-12 November in the capital Freetown, whilst symptomatic. The training was attended by 35 local and several international participants from the Netherlands and the United Kingdom- who have all subsequently been identified as contacts.

Treatment with antimalarials and antibiotics did not improve his condition, so he was evacuated in an air ambulance to the Netherlands (via Morocco) on 19 November. Unaware of the doctor's Lassa fever infection, no specific personal protective equipment was used, the four German flight staff are moderate risk contacts. The doctor tested positive for Lassa fever on 20 November and died on 23 November.

A second Dutch healthcare worker was confirmed to have Lassa Fever on 22 November - likely infected when they also participated in the surgery at Masanga hospital on 4 November. This person was then medically evacuated in an high containment unit to the Netherlands and is in treatment in isolation.

Further investigation has identified two further cases among local healthcare workers at Masanga Hospital, both of whom also were involved in the surgery on 4 November. All high-risk contacts in Masanga Hospital are under follow-up.

Several Dutch contacts in Sierra Leone have been identified; five high-risk contacts have been evacuated back to the Netherlands for monitoring and the remainder low-risk contacts are self-monitoring in Sierra Leone.

The four German flight crew are being monitored until 10 December (21 days after their exposure on 19 November).

Eighteen UK nationals have been identified as contacts of the first Dutch case. Eight are high risk and were exposed while working with the Dutch doctor at Masanga Hospital or from the two patients who are probable cases. Ten further low-risk UK contacts were possibly exposed while at the training event in Freetown. One high-risk contact travelled on to Uganda on 16 November as is being followed-up by authorities there. The remaining 17 contacts have all returned to the UK for follow-up.

Moroccon authorities have implemented control measures for potentially exposed staff at Agadir Airport where the air ambulance with the Dutch doctor transited through on 19 November.

Sierra Leone is endemic for Lassa fever and reports cases every year. In 2019, ten cases have been confirmed in Kenema district as of 17 November, with six fatalities. The WHO advise against any trade or travel restrictions for Sierra Leone.

Updated 26 November: An outbreak of Lassa fever has been declared in Sierra Leone. Eight cases have been identified in a cluster linked to Masanga Hospital in Tonkolili District. These include two Dutch healthcare workers who were confirmed infected after evacuation to the Netherlands, one of whom passed away on 23 November. Four further healthcare workers at the hospital are confirmed or suspected to be infected.

Investigations into the outbreak have identified two women who were operated on for maternal-related issues on the 4th November and subsequently died. They are probable cases and considered the origin of the outbreak.

At least 48 contacts have been identified and are being monitored in Denmark, Germany, Sierra Leone, the Netherlands, Uganda and the United Kingdom. Moroccon health authorities have been informed to take necessary precautionary measures although it is not yet clear whether there is any contact monitoring ongoing in the country.

Published 24 November: Dutch authorities advise that two doctors confirmed infected with Lassa fever in the course of their work in Sierra Leone, have been evacuated to hospitals in the Netherlands. One, who was treated at the Leiden University Medical Centre has died, while the other is being treated in strict isolation in the University Medical Centre in Utrecht. "Several other" healthcare workers who were in contact with them have also been transported back to the Netherlands on a special flight. News sources indicate the number to be five people.

Unverified information indicates three British doctors have also been returned home for investigation and monitoring. Health authorities in the United Kingdom have contacted 15 other British staff who had contact with the Dutch doctors. Apparently the Dutch and British medical teams had operated on a pregnant woman in Tonkolili district, Sierra Leone. A local anaesthetist is said to have been confirmed infected with Lassa fever too.

There is no indication of spread in the Netherlands or United Kingdom.

Lassa fever risk is consistently present in Sierra Leone.