[Rash and fever illness caused by herpes simplex virus type 1 needs to be distinguished from hand, foot and mouth...

An epidemic of rash and fever illnesses suspected of hand, foot and mouth disease (HFMD) occurred in Gansu Province of China in 2008, laboratory tests were performed in order to identify the pathogen that caused this epidemic. Eight clinical specimens collected from the 4 patients (each patient has throat swab and herpes fluid specimens) with rash and febrile illness, were inoculated onto RD and HEp-2 cells for virus isolation, and the viral nucleic acid was then extracted with the positive virus isolates, the dual-channel real-time reverse transcript-polymerase chain reaction (RT-PCR) was performed to detect the nucleic acid of human enterovirus (HEV) in the viral isolates at the same time. For the viral isolates with the negative results of HEV, a sequence independent single primer amplification technique (SISPA) was used for "unknown pathogen" identification. Totally, 6 viral isolates were identified as herpes simplex virus type 1 (HSV-1). Comprehensive analyses results of the clinical manifestations of the patients, epidemiological findings and laboratory test indicated that this epidemic of rash and febrile illness was caused by HSV-1. The differences among the gG region of 6 HSV-1 isolates at nucleotide level and amino acid level were all small, and the identities were up to 98. 8% and 97.9%, respectively, showing that this outbreak was caused by only one viral transmission chain of HSV-1. HSV-1 and other viruses that cause rash and febrile illnesses need differential diagnosis with HFMD. The etiology of rash and febrile illness is sometimes difficult to distinguish from the clinical symptoms and epidemiological data, the laboratory diagnosis is therefore critical.