In an outbreak of measles in Gothenburg, Sweden, breakthrough infections (i.e. infections in individuals with a history of vaccination) were common. The objective of this study was to compare measles RNA levels between naïve (i.e. primary) and breakthrough infections. We also propose a fast provisional classification of breakthrough infections. Medical records were reviewed and real-time PCR-positive samples genotyped. Cases were classified as naïve, breakthrough or vaccine infections. We compared clinical symptoms and measles RNA cycle threshold (Ct) values between breakthrough and naïve infections. Sixteen of 28 confirmed cases of measles in this outbreak were breakthrough infections. A fast provisional classification, based on previous history of measles vaccination and detectable levels of measles IgG in acute serum, correctly identified 14 of the 16 breakthrough infections, confirmed by IgG avidity testing. Measles viral load was significantly lower in nasopharyngeal samples from individuals with breakthrough compared with naïve infections (median Ct-values: 32 and 19, respectively, p < 0.0001). No onward transmission from breakthrough infections was identified. Our results indicate that a high risk of onward transmission is limited to naïve infections. We propose a fast provisional classification of breakthrough measles that can guide contact tracing in outbreak settings.
Human rhinovirus (HRV) is a highly prevalent pathogen and a major cause of acute respiratory tract infection (ARTI). HRV express less seasonality than other viral ARTIs, which typically appear as seasonal epidemics lasting for 1-2 months. The aim of this study was to investigate the seasonal patterns of HRV types over four consecutive years in one geographic region. HRV identified in respiratory samples from 114 patients over a four-year period were analysed by VP4/VP2 sequencing. HRV-A was found in 64, HRV-B in 11 and HRV-C in 37 cases. Overall, 33 different HRV-A types, nine B types and 21 C types were found. As many as 21 of the HRV types appeared during several seasons, with a maximum time-span of four years. Some types appeared during successive seasons and, in some cases, phylogenetic analysis indicated extended periods of circulation locally. Most of the strains were closely related to HRV identified in other parts of the world during the same time period. HRV strains that circulate locally represent many types and seem to reflect that HRV infections are highly globalised. The existence of simultaneous or successive epidemics with different HRV types in combination with the ability of each type to remain in the local population over extended periods of time may contribute to explaining the high rate of HRV infections.
We describe an imported case of Lassa fever with both encephalopathy and bilateral sensorineural hearing deficit. Absence of fever during hospitalization, initially nonspecific symptoms, and onset of hearing deficit in a late stage of disease probably contributed to delayed diagnosis (14 days after admittance to hospital). The pathogenesis of neurological manifestations of Lassa fever is poorly understood and no specific treatment was given. A total of 118 personnel had close contact with the patient, but no secondary cases occurred. This case highlights the importance of considering Lassa fever as a differential diagnosis in patients with recent travel to endemic areas.
Background Nosocomial transmission of influenza A virus (InfA) infection is not fully recognized. The aim of this study was to describe the characteristics of hospitalized patients with InfA infections during an entire season and to investigate in-ward transmission at a large, acute-care hospital. Methods During the 2016–17 season, all hospitalized patients ≥18 years old with laboratory-verified (real-time polymerase chain reaction) InfA were identified. Cases were characterized according to age; sex; comorbidity; antiviral therapy; viral load, expressed as cycle threshold values; length of hospital stay; 30-day mortality; and whether the InfA infection met criteria for a health care–associated influenza A infection (HCAI). Respiratory samples positive for InfA that were collected at the same wards within 7 days were chosen for whole-genome sequencing (WGS) and a phylogenetic analysis was performed to detect clustering. For reference, concurrent InfA strains from patients with community-acquired infection were included. Results We identified a total of 435 InfA cases, of which 114 (26%) met the HCAI criteria. The overall 30-day mortality rate was higher among patients with HCAI (9.6% vs 4.6% among non-HCAI patients), although the difference was not statistically significant in a multivariable analysis, where age was the only independent risk factor for death (P < .05). We identified 8 closely related clusters (involving ≥3 cases) and another 10 pairs of strains, supporting in-ward transmission. Conclusions We found that the in-ward transmission of InfA occurs frequently and that HCAI may have severe outcomes. WGS may be used for outbreak investigations, as well as for evaluations of the effects of preventive measures.
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