As this issue went to press, the CDC confirmed that a patient admitted to Emory University Hospital’s Serious Communicable Diseases Unit has Lassa fever, a hemorrhagic virus endemic in parts of West Africa.
Lassa is not considered as deadly or as easily transmitted as Ebola, but of course we have seen that incoming exotic diseases do not always follow predicted behavior patterns. There has never been a reported case of Lassa fever transmission in the United States, but given that was also said about Ebola and Zika virus, we must certainly hope it remains the case. However, Emory’s containment unit is state of the art, and the team led by Bruce Ribner, MD, successfully treated four Ebola patients during that outbreak.
There have been Lassa fever patients treated in the U.S. before, including one who died last year in a New Jersey hospital.
The recently admitted Lassa fever patient is an American physician assistant working for a missionary organization in Togo, West Africa. The virus can be transmitted by infected humans, but only through direct contact with bodily fluids — not through casual contact nor the airborne route.
While Ebola is thought to have an animal reservoir in bats, Lassa is carried in Africa by the “multimammate rat,” which can excrete virus in urine and may colonize homes if it finds a food source. Similar to Hantavirus, viral particles from rodent excretions can be inhaled by people, particularly if they are sweeping up or otherwise stirring a contaminated area. It can also be ingested if food is contaminated.
In Africa, healthcare workers can acquire the virus from patients if proper PPE is not used and they have blood or body fluid exposures. It can also be transmitted through contaminated equipment or needlesticks. Approximately 15%-20% of patients hospitalized in Africa with Lassa fever die from the illness. However, only 1% of all Lassa virus infections — including those in the community — result in death.
DEATH IN NJ
In the aforementioned New Jersey case, a patient traveled from Liberia to Morocco to JFK International Airport on May 17, 2015. The patient did not have a fever on departure from Liberia, did not report symptoms such as diarrhea, vomiting, or bleeding during the flight, and his temperature was taken on arrival in the U.S. and he did not have a fever at that time.
On May 18, the patient went to a hospital in New Jersey with symptoms of a sore throat, fever and tiredness. According to the hospital, he was asked on the 18 about his travel history and he did not indicate travel to West Africa. The patient was sent home the same day, and returned to the hospital on May 21 when symptoms worsened. The patient was transferred to a second hospital prepared to treat viral hemorrhagic fevers. Samples submitted to CDC tested positive for Lassa fever. Tests for Ebola and other viral hemorrhagic fevers were negative. The patient was in appropriate isolation when he died shortly thereafter and no secondary cases occurred.