A New Segmented Virus Associated with Human Febrile Illness in China - A review
The article we suggest to read this week is "A New Segmented Virus Associated with Human Febrile Illness in China", published on The New England Journal of Medicine last May.
Routine surveillance for tickborne diseases in China led to the identification of a patient from the town of Alongshan who had a febrile illness with an unknown cause. Analyses revealed a previously unknown segmented RNA virus, which we designated Alongshan virus (ALSV), that belongs to the unclassified jingmenvirus group in the family Flaviviridae, which includes the genera flavivirus, pestivirus, hepacivirus, and pegivirus. ALSV was also detected in additional patients with fever and headache as well as in ticks and mosquitoes in the region. The authors describe the discovery, isolation, and characterization of the virus.
ALSV is able to infect multiple human cell lines, induce pathologic changes in mice, and cause inflammatory responses in patients. Although ALSV is genetically different from Jingmen tick virus (JMTV), it is more closely related to JMTV than it is to other jingmenviruses. JMTV was first isolated from Rhipicephalus microplus in China, and it has a wide range of hosts, including cattle, dogs, and goats, and a wide geographic distribution in China. JMTV variants have also been identified in other countries.
ALSV infection should be differentiated from thrombocytopenia syndrome virus (SFTSV), tickborne encephalitis virus (TBEV), human anaplasmosis, rickettsiosis, and leptospirosis.
The authors suspect that ALSV is transmitted by the tick I. persulcatus, whose common hosts include most mammals (e.g., sheep, cattle, horses, dogs, rabbits, humans) and occasionally some birds. I. persulcatus is widely distributed in Asia and eastern Europe. However, mosquitoes cannot be excluded as a possible vector, as ALSV RNA was detected in mosquitoes in the province of Jilin in northeastern China, and the RNA from these mosquitoes was found to be genetically related to that from the patients and ticks assessed by the authors.
The authors conclude highlighting that ALSV may be the cause of a previously unknown febrile disease, and that more studies should be conducted to determine the geographic distribution of this disease outside its current areas of identification.
AUTHORS: Ze-Dong Wang, Bo Wang, Feng Wei, Shu-Zheng Han, Li Zhang, Zheng-Tao Yang, and others.
Full article is available on the The New England Journal of Medicine webiste.
A case-control study about national outbreak of pertussis in England, 2011–2012
This week WAidid suggests to read "National Outbreak of Pertussis in England, 2011–2012: A Case-control Study Comparing 3-Component and 5-Component Acellular Vaccines With Whole-cell Pertussis Vaccines", an article published in May 2019 on the Oxford Academic Journal.
Whooping cough, a respiratory disease caused by Bordetella pertussis, remains a disease of global public health importance. Despite a significant reduction in global burden of disease following the introduction of routine whole-cell pertussis (wP) immunization in the 1950s, the disease remains endemic worldwide, with sporadic outbreaks and epidemic peaks observed every 2–5 years. Young unimmunized infants are at highest risk of severe complications and death from pertussis. Protection conferred either through vaccination or natural infection is not lifelong, and older vaccinated individuals can present with milder, often atypical symptoms, leading to delays in diagnosis and risk of transmission to unvaccinated children. In the 1970s, following concerns about the safety of wP vaccines, less-reactogenic acellular pertussis (aP) vaccines were developed. Acellular vaccines were ﬁrst introduced into the routine UK immunization schedule in October 2001, as part of the preschool booster (PSB) dose, oﬀered to children aged 3–5 years. Following a long period of good pertussis control, from 2011 an increase in laboratory-conﬁrmed cases was observed across England. In the 2015 position paper, WHO concluded that the switch to aP vaccines contributed to a genuine resurgence of pertussis, and therefore it recommended to continue use wP for primary vaccination series.
The authors reported the data of a retrospective case-control study which compared the effectiveness of the aP vaccines currently licensed for the primary childhood immunization program in England (3-component acellular pertussis vaccine [aP3] and aP5) with the wP vaccines previously used, and the effectiveness of the different acellular PSB vaccines, in children aged 5 to 15 years, during the national outbreak in 2011 and 2012.
They reported that primary vaccination courses (3 doses of aP3) were more likely to be associated with disease than primary courses (3 doses of wP). There was no signiﬁcant diﬀerence in protection among individuals who received 3 doses of aP5 and those who received 3 doses of wP, although the fact that aP5 cohorts were younger in age and therefore closer to vaccination limits the interpretation of this ﬁnding.
The authors highlighted that their study provides important evidence that priming with a aP5 vaccine might have a similar protective eﬀect to the wP vaccine previously used in the accelerated UK schedule. Furthermore, as the type of pertussis vaccine used for PSB appears to have little impact on the overall protection, there remains greater ﬂexibility over the choice of pertussis vaccine for booster doses.
AUTHORS: Carlos F A Carvalho, Nick Andrews, Gavin Dabrera, Sonia Ribeiro, Julia Stowe, Mary Ramsay, Gayatri Amirthalingam.
To read the full article click here.