Five infected, four dead. This is the result of the only documented outbreak of Lujo virus. We are in Zambia and South Africa in 2008 (the name of the virus comes from the first two letters of Lusaka and Johannesburg) when the examination of mysterious patients brings to light a virus never before found in a human body. Its mortality rate of 80% places it among the Marburg and Ebola viruses, and only behind rabies which is alone in the lead at 99%.
The first patient infected with Lujo is a 36-year-old Zambian traveler. She developed mild symptoms shortly before flying to South Africa for a wedding. It was only upon his return to Zambia that the symptoms worsened. Except that we only suspect the flu or food poisoning. As her condition became more and more critical, the decision was finally made to transfer her to a hospital in Johannesburg. Too late. She died thirteen days after the first symptoms.
Lujo’s second and third patients are two medical staff who cared for patient zero on her flight to Johannesburg. They also die because it is difficult to diagnose this viral hemorrhagic fever, and therefore to take appropriate measures to limit any transmission. Two other fatal cases surface, once again located in hospital. Only the fifth and final patient survives. The authorities had had time to recognize the infectious nature of the disease.
So how does Lujo act? Almost two weeks after infection, fever, headache and muscle pain appear. The patients’ condition then deteriorates quite quickly. Rashes, swelling of the face and neck, diarrhea and sore throat occur. If we are talking about “hemorrhagic fever”, bleeding is not one of the common symptoms, as explained by the American Centers for Disease Control and Prevention and unlike Ebola.
Patients who eventually die from Lujo first experience some improvement, before having respiratory, heart and nerve problems. Death occurs between ten and thirteen days after the first symptoms.
Zoonotic pathogen
From smallpox to Ebola and all kinds of flu, humanity has learned to more or less tame its microscopic adversaries. The Covid-19 pandemic has nevertheless reminded us that certain viruses can sometimes surprise our scientists and slip through the cracks. The Lujo virus is one of them. It is a zoonotic pathogen, meaning it has spread from an animal population to humans at some point. The good news is that so far it seems too deadly to generate a pandemic.
Lujo belongs to the family of Arenaviridaejust like the Lassa virus to which it is very close genetically. Viruses that have an envelope and an RNA genome, and generally originate from rodents. Nothing to do with an arena: they take their name from the Latin “arenosus“, or “sandy”, since they resemble grains of sand when observed under a microscope.
A 2024 study tells us that the Lujo virus is, to our knowledge, the only Arenaviridae to use the human protein neuropilin-2 to enter cells. By studying how the virus’s Spike protein binds to neuropilin-2, the authors of this study say they are on the trail of a treatment.
As for human-to-human contamination, Lujo is believed to be transmitted via bodily fluids. According to another study, this time from 2016, infected people do not seem contagious “only in the final stages of the illness, perhaps in the last three days before death. Which makes a contamination window probably shorter than (that of Ebola).” This is surely what limited the 2008 epidemic to only five people. On the other hand, the story can be even more serious if a patient seeks help in the overwhelmed clinic in a densely populated area. Or if other infections create, in the meantime, immune deficiencies in the population.
