Yellow Fever Virus Detected in Urine of Convalescent Patient

In most cases, the symptoms disappear after three or four days. A small percentage of those infected enter a second, more toxic stage within 24 hours of recovery from the initial symptoms, and half of these die within a period of seven to 10 days.

Brazilian scientists at University of São Paulo (São Paulo, Brazil) and their colleagues tested the urine and semen of a patient who survived the disease almost a month after the patient was infected. The patient showed a moderate clinical presentation: anicteric form and mild spontaneous hemorrhage (ecchymosis in the right eye). High fever, gastrointestinal symptoms (vomiting and diarrhea), weakness, adynamia, and generalized myalgia were also observed. The patient had a weight loss of 4 kg over eight days and the patient also had severe thrombocytopenia (platelet count 77,000/mm3).

The team obtained serum, urine, and semen samples and extracted virus RNA by using the NucliSENS EasyMag Kit (bioMérieux, Marcy l’Étoile, France). They tested samples for YFV RNA by using a real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and primers specific for YFV and a conventional PCR and pan flavivirus primer. Serum samples showed negative results for both PCRs. However, a urine sample obtained 10 days after initial symptoms was positive for YFV RNA (cycle threshold [Ct] 17.42, 9.3 × 106 RNA copies/mL) by qRT-PCR. They also performed a qualitative IgM-capture ELISA with a specific virus antigen and obtained positive results. The analysis showed that the virus belonged to a group of genotypes isolated in South America, including two isolated in 2017 in Espírito Santo State.

The authors concluded that semen can be a useful clinical material for diagnosis of yellow fever and indicate the need for testing urine and semen samples from patients with advanced disease. Such testing could improve diagnostics, reduce false-negative results, and strengthen the reliability of epidemiologic data during ongoing and future outbreaks. The study was published in the January 2018 issue of the journal Emerging Infectious Diseases.