Long-term retrospective observation reveals stabilities and variations of hantavirus infection in Hebei, China

Epidemiology of Hemorrhagic Fever with Renal Syndrome and Host Surveillance in Zhejiang Province, China, 1990-2021

Hemorrhagic fever with renal syndrome (HFRS) is caused by hantaviruses (HVs) and is endemic in Zhejiang Province, China. In this study, we aimed to explore the changing epidemiology of HFRS cases and the dynamics of hantavirus hosts in Zhejiang Province. Joinpoint regression was used to analyze long-term trends in the incidence of HFRS. The comparison of animal density at different stages was conducted using the Mann-Whitney Test. A comparison of HV carriage rates between stages and species was performed using the chi-square test. The incidence of HFRS shows a continuous downward trend. Cases are widely distributed in all counties of Zhejiang Province except Shengsi County. There was a high incidence belt from west to east, with low incidence in the south and north. The HFRS epidemic showed two seasonal peaks in Zhejiang Province, which were winter and summer. It showed a marked increase in the age of the incidence population. A total of 23,073 minibeasts from 21 species were captured. Positive results were detected in the lung tissues of 14 rodent species and 1 shrew species. A total of 80% of the positive results were from striped field mice and brown rats. No difference in HV carriage rates between striped field mice and brown rats was observed (χ2 = 0.258, p = 0.611).

Diversity and genetic characterization of orthohantavirus from small mammals and humans during 2012-2022 in Hubei Province, Central China

Hemorrhagic fever with renal syndrome (HFRS) is a significant public health problem in Hubei Province, China, where a novel strain of orthohantavirus, HV004, was reported in 2012. However, no systematic study has investigated the prevalence and variation of orthohantavirus in rodents and humans. Herein, 2137 small mammals were collected from ten HFRS epidemic areas in Hubei Province from 2012 to 2022, and 143 serum samples from patients with suspected hemorrhagic fever were collected from two hospitals from 2017 to 2021. Orthohantavirus RNA was recovered from 134 lung tissue samples from five rodent species, with a 6.27 % prevalence, and orthohantavirus was detected in serum samples from 25 patients. Genetic analyses revealed that orthohantavirus hantanense (HTNV), orthohantavirus seoulense (SEOV), and orthohantavirus dabieshanense (DBSV) are co-circulating in rodents in Hubei, and HTNV and SEOV were identified in patient serum. Phylogenetic analysis showed that most of the HTNV sequences were clustered with HV004, indicating that HV004-like orthohantavirus was the main HNTV subtype in rodents. Two genetic reassortments and six recombination events were observed in Hubei orthohantaviruses. In summary, this study identified the diversity of orthohantaviruses circulating in Hubei over the past decade, with the HV004-like subtype being the main genotype in rodents and patients. These findings highlight the need for continued attention and focus on orthohantaviruses, especially concerning newly identified strains.

Genetic diversity and molecular evolution of Seoul virus in Hebei province, China

Seoul virus (SEOV) is a major pathogen which causes hemorrhagic fever with renal syndrome (HFRS), and is present all over the world. However, there are currently few long-term systematic studies of SEOV's phylogenetic and evolutionary mechanisms in epidemic areas. Thus, in this study, we used RT-PCR combined with NGS to obtain the genomes of six SEOV viruses from 1993, as well as 56 Hebei province-specific tissue samples from 1999 to 2022. Phylogenetic analysis showed that the SEOV samples could be divided into seven groups and showed geographic clustering. The geographic region may be the main factor affecting the genetic diversity of SEOV. We also found that SEOV was subject to strong overall purifying selection and positive selection at certain sites during evolution. Recombination events and high nucleotide substitution rates were also shown to accelerate SEOV's evolution. Evolutionary feature of the L segment is more representative of complete genome. Our detailed analysis provides a deeper understanding of the genetic diversity and evolutionary drivers of SEOV within its primary epidemic areas. It will be important to further monitor epidemiological trends and drivers of variation to help increase our understanding of the pathogenicity of SEOV infections.

Orthohantavirus infections in humans and rodents in the Yichun region, China, from 2016 to 2021

BACKGROUND

Rodents are the predominant natural hosts of orthohantavirus and the source of human infection, hemorrhagic fever with renal syndrome (HFRS) caused by orthohantavirus is a severe public health problem in the Yichun region, Jiangxi Province, China. However, little information is known about the infection of orthohantavirus in humans and rodents, and the genetic characteristics of the epidemic orthohantavirus in the region.

METHODS

The clinical data of HFRS cases in 2016-2021 was analyzed. Virus infection in rodents was analyzed by orthohantavirus antigen detection using immunofluorescent assay, and the species of orthohantaviruses in rodents and patients were identified by real-time RT-PCR and gene sequencing. The S and M segments of orthohantaviruses from rodents and patients were recovered and analyzed.

RESULTS

A total of 1,573 HFRS cases were reported in the Yichun region from 2016 to 2021, including 11 death cases. HFRS cases peaked twice each year: in winter from November to January and early summer from May to June. Farmers constituted the predominant population suffering from HFRS. The orthohantavirus antigen was identified in five species of rodents: Apodemus agrarius (A. agrarius), Rattus norvegicus (R. norvegicus), Sorex araneus, Rattus losea (R. losea), and Niviventer confucianus (N. confucianus). The real-time RT-PCR test and genetic analysis results showed that Hantaan orthohantavirus (HTNV), Seoul orthohantavirus (SEOV), and Dabieshan orthohantavirus (DBSV) were circulated in the rodents. HTNV, SEOV, and DBSV from the rodents were distantly related to other known orthohantaviruses and belonged to novel genetic lineages. SEOV and HTNV were found in HFRS patients, but 97.8% (90/92) of the infections were caused by HTNV. Winter and early summer peaks were both caused by HTNV. The HTNV sequences recovered from HFRS cases were closely related to those from A. agrarius.

CONCLUSIONS

In the Yichun region, the orthohantaviruses transmitted in rodents include HTNV, SEOV, and DBSV, which have obvious genetic characteristics and high genetic diversity. At the same time, this region is an HFRS mixed epidemic area dominated by HTNV, with two peaks every year, which deserves our high attention.

The changing epidemiology of hemorrhagic fever with renal syndrome in Southeastern China during 1963-2020: A retrospective analysis of surveillance data

Background

Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by hantavirus which was endemic Zhejiang Province, China. In this study, we aim to explore the changing epidemiology of HFRS in Zhejiang, identify high-risk areas and populations, and evaluate relevant policies and interventions to better improve HFRS control and prevention.

Methods

Surveillance data on HFRS during 1963–2020 in Zhejiang Province were extracted from Zhejiang Provincial Center for Disease Control and Prevention archives and the Chinese Notifiable Disease Reporting System. The changing epidemiological characteristics of HFRS including seasonal distribution, geographical distribution, and demographic features, were analyzed using joinpoint regression, autoregressive integrated moving average model, descriptive statistical methods, and Spatio-temporal cluster analysis.

Results

From 1963 to 2020, 114 071 HFRS cases and 1269 deaths were reported in Zhejiang Province. The incidence increased sharply from 1973 and peaked in 1986, then decreased steadily and maintained a stable incidence from 2004. HFRS cases were reported in all 11 prefecture-level cities of Zhejiang Province from 1963 to 2020. The joint region (Shengzhou, Xinchang, Tiantai, and surrounding areas), and Kaihua County are the most seriously affected regions throughout time. After 1990, the first HFRS incidence peak was in May-June, with another one from November to January. Most HFRS cases occurred in 21- (26.48%) and 30- years group (24.25%) from 1991 to 2004, but 41- (25.75%) and 51-years (23.30%) had the highest proportion from 2005 to 2020. Farmers accounted for most cases (78.10%), and cases are predominantly males with a male-to-female ratio of 2.6:1. It was found that the median time from onset to diagnosis was 6.5 days (IQR 3.75–10.42), and the time from diagnosis to disease report was significantly shortened after 2011.

Conclusions

We observed dynamic changes in the seasonal distribution, geographical distribution, and demographic features of HFRS, which should be well considered in the development of control and prevention strategies in future. Additional researches are warranted to elucidate the environmental, meteorological, and social factors associated with HFRS incidence in different decades.

This study conducted a long-term and systematic study on the epidemiological characteristics of HFRS in Zhejiang Province from 1963 to 2020 through a combination of time and space analysis and epidemiology, aiming to analyze the distribution characteristics of HFRS and explore the high incidence of epidemics in Zhejiang Province Regional influence. From 1963 to 2020, all 11 prefecture-level cities in Zhejiang Province reported HFRS cases, and the morbidity and mortality rates decreased significantly. However, the geographical distribution of endemic areas has been expanding to eastern Zhejiang Province. Moreover, the age of high-risk groups increases over time. Although the incidence rate has declined in recent years, HFRS is still a huge threat to people’s health. As the incidence rate changes, some epidemiological characteristics have also changed. Comprehensive interventions should also be adjusted, including rodent control in endemic areas, health education, vaccination, and improved detection and diagnosis capabilities for HFRS epidemiological changes.