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Objective To analyze the genetic characteristics of breakthrough varicella-zoster virus infection during the varicella outbreaks in Minhang District of Shanghai in 2013-2014. Methods Samples of the varicella-zoster liquid were collected from patients with chickenpox in Minhang District in 2013-2014 and used for the extraction of genomic DNA. The open reading frame ( ORF) of 22 and 62 regions were se-quenced and further analyzed by using bioinformatics methods. Results A total of 24 samples were success-fully collected and sequenced, and all of them were wild strains. Among the 24 varicella-zoster virus strains, 23 strains were highly homologous to the parental strain ( P-Oka) and the vaccine strain ( V-Oka) , indica-ting that they belonged to J genotype. Only one strain, whose genotype was between M and E, was highly ho-mologous to the mosaic( M) CA123 strain ( M1 genotype) , indicating that it might belong to M1 genotype. Conclusion The epidemic strains of varicella-zoster virus in Minhang District were mainly J genotype. Lo-cal epidemic of M and other genotypes of varicella-zoster virus also existed. There were some gene variations in different strains of J genotype. These varicella-zoster virus strains of non-vaccine genotypes might be one of the reasons causing the breakthrough cases of chicken pox.
RESUMO
OBJECTIVE: To identify the etiology and risk factors of undifferentiated fever in a cluster of patients in Western Province, Solomon Islands, May 2014. METHODS: An outbreak investigation with a case control study was conducted. A case was defined as an inpatient in one hospital in Western Province, Solomon Islands with high fever (> 38.5 °C) and a negative malaria microscopy test admitted between 1 and 31 May 2014. Asymptomatic controls matched with the cases residentially were recruited in a ratio of 1:2. Serum samples from the subjects were tested for rickettsial infections using indirect micro-immunofluorescence assay. RESULTS: Nine cases met the outbreak case definition. All cases were male. An eschar was noted in five cases (55%), and one developed pneumonitis. We did not identify any environmental factors associated with illness. Serum samples of all five follow-up cases (100%) had strong-positive IgG responses to scrub typhus. All but one control (10%) had a moderate response against scrub typhus. Four controls had low levels of antibodies against spotted fever group rickettsia, and only one had a low-level response to typhus group rickettsia. DISCUSSION: This outbreak represents the first laboratory-confirmed outbreak of scrub typhus in the Western Province of Solomon Islands. The results suggest that rickettsial infections are more common than currently recognized as a cause of an acute febrile illness. A revised clinical case definition for rickettsial infections and treatment guidelines were developed and shared with provincial health staff for better surveillance and response to future outbreaks of a similar kind.