Lujo hemorrhagic fever (LUHF) is caused by Lujo virus, a single-stranded virus of the Arenaviridae family. The limited clinical information about LUHF comes from a small, nosocomial cluster of hemorrhagic disease in September-October 2008 involving 5 patients in South Africa. The case fatality rate was 80% (4/5 cases).

The first patient, whose source of infection was unknown, was the source of infection of 3 health care workers. A tertiary infection occurred in a fourth healthcare worker who received ribavirin treatment and was the only survivor. Lujo virus is the second African hemorrhagic fever virus described. (Lassa virus was identified in 1969.)

Like all arenaviruses, Lujo virus has a rodent host as its reservoir. Humans can contract LUHF through contact with an infected rodent. Contact can be direct or through inhalation of aerosolized Lujo virus from the urine or feces of infected rodents.

Person-to-person transmission of Lujo virus was observed in the small, nosocomial cluster of hemorrhagic disease which resulted in the discovery of the Lujo virus.

Transmission of arenaviruses, and Lujo virus in particular, is most likely the result of direct contact with the body fluids of an infected person, in the absence of infection control precautions.

The symptoms of Lujo hemorrhagic fever, as described in the five patients in the original cluster outbreak, resemble those of severe Lassa Fever. After an incubation period of 7 to 13 days, the clinical course started by a non-specific febrile illness accompanied by headache and muscle pain.

The disease increases in severity, with:

• a morbilliform rash of the face and trunk
• face and neck swelling
• pharyngitis (sore throat)
• diarrhea

Bleeding was not a prominent feature during the illness.

In the fatal cases (4/5 patients), a transient improvement was followed by:

• rapid deterioration with respiratory distress
• neurological signs and circulatory collapse

Death occurred 10 to 13 days after onset.

Low blood platelets, low white blood cell count (at the onset, rising later on) and elevated liver function values were present in all patients.

Since Arenaviruses may enter the fetus through infection of the mother, and anecdotal evidence suggests that infected pregnant women may suffer miscarriages, it is reasonable to assume that both infection of the fetus and miscarriage may be associated with Lujo infection in the mother.

Lujo hemorrhagic fever (LUHF) occurs in southern Africa. The initial case was certainly infected in Zambia.

Field workers

Field workers are at greatest risk because of increased human contact with the reservoir rodent population. Sexual partners of field workers may be at greater risk as well. In addition to nosocomial infection in healthcare workers already described, laboratory infections have been frequently described with Arenaviruses and Lujo virus can certainly be transmitted to laboratory workers during manipulation of the virus, especially during experimental infections of rodents.

During the acute febrile phase, Lujo virus was isolated from blood from days 2 to 13 after onset. Virus was also isolated from liver tissue obtained post-mortem. A subsequent complete genomic analysis of Lujo virus facilitated the development of specific molecular detection (RT-PCR) assays.

Serologic diagnosis of Lujo hemorrhagic fever can be made by indirect immunofluorescent assay and ELISA. However, individuals from endemic areas displaying fever, rash, pharyngitis, accompanied by laboratory findings of low platelet counts and elevated liver enzymes, should be suspected of having a hemorrhagic fever virus infection. Clinical specimens should be tested using specific assays.

Supportive therapy is important in Lujo hemorrhagic fever. This includes:

• maintenance of hydration
• management of shock
• sedation
• pain relief
• usual precautions for patients with bleeding disorders
• transfusions (when necessary)

Treatment of arenavirus hemorrhagic fevers with convalescent plasma therapy reduces mortality significantly and anectodal evidence from the only surviving Lujo patient shows that the antiviral drug ribavirin may hold promise in the treatment of LUHF. Ribavirin has been considered for preventing development of disease in people exposed to other arenaviruses.

Recovery

The precise mortality of LUHF is unknown, but 4 of 5 described cases were fatal.

Patients who have suffered from other arenaviruses may excrete virus in urine or semen for weeks after recovery. For this reason, these fluids should be monitored for infectivity, since convalescent patients have the potential to infect others (particularly sexual partners) via these fluids.

Because infection with Lujo virus can produce severe hemorrhagic symptoms in humans, researchers studying Lujo virus must work only in BSL4 laboratories, where the most stringent safety and security conditions are in effect. In the United States, Lujo virus is classified as a Select Agent.

Although rodent control would be desirable, it will not be a successful strategy for preventing Lujo hemorrhagic fever cases caused by exposures outdoors.

As for other hemorrhagic fevers, full barrier nursing procedures should be implemented during management of suspected or confirmed LUHF cases (no infection occurred after their implementation in South Africa).