Case history
Case history #1
A 25-year-old female researcher has returned to the UK from conducting field work with Ebola survivors in eastern Sierra Leone. During her time there she would stay overnight in the houses of local families. On arrival in the UK she is febrile and feels unwell with a dry cough and some throat pain. She presents to the emergency department in a large teaching hospital 14 days after arrival where she is assessed by an infectious diseases clinician. Her history and geography lead to a suspicion of a viral haemorrhagic fever, falciparum malaria, or typhoid. She is transferred to an isolation ward and all healthcare staff in close contact with her don full personal protective equipment. She has no other symptoms and was taking malaria prophylaxis. On examination she is febrile at 38.5°C, her blood pressure is 100/60 mmHg and heart rate 100 bpms. There is abdominal tenderness diffusely, and she has some pharyngeal inflammation and tonsillar swelling. She complains of being deaf in the right ear. Blood samples are collected by the infectious diseases team and sent to a reference laboratory in the UK with biosafety level 4 capabilities. The samples are tested initially for malaria parasites (using a rapid diagnostic test), typhoid (using blood and stool cultures), and Lassa virus and Ebola virus RNA (using reverse transcription-polymerase chain reaction [RT-PCR]). FBC, urea/electrolytes, lactate, arterial blood gases, clotting, and liver function tests are also measured. The malaria blood film is negative, and blood and stool cultures are negative for Salmonella enterica. Her RT-PCR is positive for Lassa fever, and she is commenced on intravenous ribavirin and intravenous fluids and analgesics. She recovers after a 2 week illness and is discharged home. Mild hearing impairment persists at the 2 year follow-up point.
Case history #2
A 40-year-old man presents to a clinic in rural Nigeria with a painful throat, weakness, headache, and fever. On examination he has posterior pharynx swelling and erythema, conjunctivitis, abdominal tenderness, and some blood oozing from his gums. No rash is visible. History reveals the patient resides in an area where rats are commonly seen.
Other presentations
Lassa fever can present in multiple different ways, but is asymptomatic or offers mild febrile symptoms in the majority of cases. Severe disease develops in approximately 20% of patients.[2] Presentation in immunocompromised individuals, including those with HIV, has not been well described. Children are an understudied population, but a case fatality rate of 27% in children in one hospital in Liberia has been described.[3] 'Swollen baby syndrome' (consisting of oedema, abdominal distension, and bleeding) was described in babies with Lassa fever in this case series.[3] In children aged 10 to 19 years, there was no significant difference in mortality compared with older adults.[4] More severe illness has been reported in pregnant women, with increased risk of maternal death when the infection occurs in the third trimester compared with the first.[5]
Symptoms that may identify Lassa fever include unilateral or bilateral sensorineural deafness, which has been reported in around 30% of cases, either during the acute phase or during convalescence, and is permanent in some cases.[6] Deafness has also been noted in those not previously diagnosed, but with serological evidence of previous infection.[6] In the largest case series of Lassa fever reported to date, the best predictor of Lassa fever includes a combination of fever, pharyngitis, retrosternal pain, and proteinuria.[4] Fever is present in virtually all patients with Lassa fever. However, it may not be continuous; therefore, being afebrile on presentation does not rule out Lassa fever.
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