#14,544
Over the weekend it has emerged that a Dutch doctor, working in Sierra Leone, has died from Lassa fever after being repatriated back to the Netherlands, and that a second Dutch doctor is in isolation and receiving treatment (see BBC report Dutch doctor dies after contracting Lassa fever in Sierra Leone).
A second report - this time from Sky News - indicates that at least 3 Britons who may have been exposed have been repatriated to the UK for tests (see Lassa fever: Britons who came into contact with victims brought back to UK for tests).While it doesn't get as much attention by the mainstream press as does its deadlier cousin Ebola, every year we see outbreaks of Lassa Fever in West Africa (see map above), often causing hundreds of infections and scores of fatalities (see
Eighteen months ago, in the WHO List Of Blueprint Priority Diseases, we looked at 8 disease threats in need of urgent accelerated research and development.
Number 3 on the list is Lassa Fever.
List of Blueprint priority diseases
(SNIP)
The second annual review occurred 6-7 February, 2018. Experts consider that given their potential to cause a public health emergency and the absence of efficacious drugs and/or vaccines, there is an urgent need for accelerated research and development for*:
- Crimean-Congo haemorrhagic fever (CCHF)
- Ebola virus disease and Marburg virus disease
- Lassa fever
- Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS)
- Nipah and henipaviral diseases
- Rift Valley fever (RVF)
- Zika
- Disease X
Lassa fever is a Viral Hemorrhagic Fever (VHF), the virus for which 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).Unfortunately, healthcare workers - particularly those working in austere or less than ideal conditions - are often exposed. In Nigeria, as of Nov 17th, 19 HCWs have been infected since January 1st.
While primarily a regional threat, during the last major outbreak (2016) exported cases turned up in several countries, including Germany and Sweden (see Germany's RKI Statement On Lassa Fever Cluster In Cologne & WHO Lassa Fever Update - Sweden (Imported)).
In 2016 the ECDC published a Rapid Risk Assessment on the spread of Lassa Fever out of West Africa. While the risk of seeing Lassa Fever outside of West Africa was determined to be low, they authors wrote:
The two imported cases of Lassa fever recently reported from Togo indicate a geographical spread of the disease to areas where it had not been recognised previously. Delays in the identification of viral haemorrhagic fevers pose a risk to healthcare facilities.
Therefore, Lassa fever should be considered for any patient presenting with suggestive symptoms originating from West African countries (from Guinea to Nigeria) particularly during the dry season (November to May), a period of increased transmission, and even if a differential diagnosis such as malaria, dengue or yellow fever is laboratory-confirmed.A reminder that in this increasingly interconnected and mobile world that localized outbreaks - no matter how remote - aren't guaranteed to remain such, and that without a proactive response they can very quickly turn into public health threats anywhere in the world.
