The research group of Zheng Aihua of the Institute of Zoology revealed that hedgehogs are the main wild reservoirs of severe fever and thrombocytopenia syndrome virus in China

Severe fever with thrombocytopenia syndrome virus (SFTSV), also known as new Bunia virus, is a tick-borne Bunia virus discovered in China in 2009, initially mainly prevalent in the Dabie Mountain Area
at the junction of Hubei-Yu-Anhui.
Its infection can cause fever with thrombocytopenia syndrome, which mainly manifests fever, thrombocytopenia and leukopenia, gastrointestinal symptoms, and multiple organ function damage
.
The main vector is the long-horned blood tick
.
The longhorned blood tick is common in the Asia-Pacific region and is one of the main ticks in the central and eastern regions of
China.
Numerous reports suggest that the longhorned blood tick can act as a viral reservoir
for SFTSV.
However, free ticks and parasitic ticks collected in the wild have very low carryover rates, so ticks alone are not sufficient to maintain the natural cycle of SFTSV in the natural environment, requiring additional wild vertebrate amplification hosts
.

Hosts of tick-borne viruses generally meet the following conditions: high density, high vector tick breeding rate, consistent with infectious disease distribution, sufficient viremia, no onset or mild symptoms, and the virus can establish a cycle
between the vector and the animal.

In China, the density of large wildlife is extremely low, especially in
eastern China, where SFTSV is endemic.
The distribution of rodents and insectivores is abundant
.
In SFTSV-endemic areas, hedgehogs are the only wild animals
with high SFTSV seroprevalence (25-33%), high density (>80 individuals/km²) and high growth rate of surface ticks (more than 100 ticks/unit).
Hedgehogs belong to the hedgehog subfamily, widely distributed in Eurasia and Africa, and the northeastern hedgehog (Erinaceus amurensis) is more common
in the north-central region of China.
The African miniature hedgehog (Atelerix albiventris) is native to central and eastern Africa and was introduced to China
as a pet.

Under laboratory conditions, we found that viremia of about 10^{6 RNA}copy number/mL was detected in both Northeast hedgehogs and African mini-hedgehogs by intraperitoneal or subcutaneous injection of 4 x 10⁶FFU SFTSV for 9 to 11 days
.
In addition, hedgehogs are highly tolerant to SFTSV infection, and after SFTSV infection, there is a slight weight loss, and tissue lesions recover
after viral clearance.

We further established the viral cycle
of SFTSV-Blood Tick-Hedgehog in the laboratory.
The results showed that the virus could be efficiently transmitted from nymph ticks or adult ticks to hedgehogs, from hedgehogs to nymph ticks or adult ticks, and from nymphs to adult ticks with 100%
transmission efficiency.
It was further confirmed that hedgehogs are the main amplification host
of SFTSV in China.

This study revealed the main vertebrate reservoirs of SFTSV natural circulation in the wild, which has important guiding significance
for studying the prevalence and spread of SFTSV.
Hedgehogs are also important urban wildlife in China, and with the continuous spread of longhorned blood ticks in urban suburbs and even urban parks, SFTSV also has the risk of spreading from rural to urban areas, and needs to be monitored
.

The study was published in December 2022 under the title "Hedgehogs as Amplifying Hosts of Severe Fever with Thrombocytopenia Syndrome Virus, China" in the epidemiological journal Emerging Infectious Diseases
.
The project has been supported
by the National Key Research and Development Program of the Ministry of Science and Technology.
The first author of this paper is Dr.
Chao Zhao of the Institute of Zoology, Chinese Academy of Sciences, and the corresponding author is Zheng Aihua, researcher of the Institute of Zoology, Chinese Academy of Sciences, researcher Jiang Jiafu, researcher of the Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, and Hao Junfeng, associate researcher
of the Institute of Biophysics, Chinese Academy of Sciences.
Article link: https://wwwnc.
cdc.
gov/eid/article/28/12/22-0668_article

Pictured: Hedgehog collection site
in the wild.

Figure: Weight changes and viremia
in Northeast hedgehogs (A, B) and African miniature hedgehogs (C, D) after SFTSV infection.