Epidemiological and phylogenetic analysis of rabies virus isolated from humans in Henan province, China

Metagenomic next-generation sequencing for etiological diagnosis of an unexpected rabies case with unclear exposure history

BACKGROUND

Rabies is an acute and lethal zoonotic disease caused by the rabies virus (RABV). After onset, there are no effective drugs or treatment methods.

CASE PRESENTATION

A 49-year-old female from Hefei, Anhui Province, China, presented to a local hospital with fever, pruritus, chest distress, and shortness of breath. During the consultation, the patient exhibited agitation and was later admitted to the intensive care unit (ICU) in the local hospital for endotracheal intubation and mechanical ventilation due to worsened agitation and dyspnea. Cerebrospinal fluid (CSF) and blood samples were collected and pathogenic microorganism identification was performed by culture and mNGS. However, all results were negative. In addition, the patient did not display typical rabies-specific symptoms such as aerophobia, hydrophobia or photophobia from onset to admission. Subsequently, saliva samples were collected for mNGS detection following consultation with experts at our hospital. Nucleic acid sequences uniquely aligned to the rabies virus (RABV) were identified in these samples. The result was further confirmed by local Center for Disease Control and Prevention (CDC) through RT-qPCR which detected part of the N gene of RABV in the saliva sample. The patient was then transferred to the ICU for isolation. Unfortunately, the patient died on the 10th day of admission due to multiple organ failure. The detection of human rabies virus IgG antibodies reported positive during the advanced stage of the disease during the hospitalization. We consistently verified with the patient's family member that there was no clear history of animal bites and no history of RABV vaccination. Furthermore, we performed phylogenetic analysis of partial L and G gene sequences of RABV obtained by mNGS (designated HFG23-L and HFG23-G, respectively), the results showed that both HFG23-L and HFG23-G belonged to the China I lineage, and shared 99.7% similarity with the Fengtai strain isolated from dogs in Beijing.

CONCLUSIONS

The identification of unique RABV sequence through mNGS in the patient's saliva sample suggested that mNGS could serve as a valuable screening tool for the etiological diagnosis of rabies, especially when timely laboratory testing was unavailable or when patients lacked non-specific prodromal symptom and clear exposure history.

Genetic characteristics and geographic distribution of rabies virus in China

China is one of the largest countries with endemic rabies. In this study, we examined the full-length genome sequences of 87 rabies virus (RABV) strains identified in China from 1931 to 2019. Chinese RABV isolates were divided into two major clades, GI and GII. Clade GI consisted of viruses from the Asian clade, which was further divided into three subclades: Asian1, Asian2, and Asian3. Clade GII consisted of viruses from the Cosmopolitan, Arctic-related, and Indian clades. A phylogeographic network showed that the variation of rabies virus was more closely associated with geographic location than with the host species. Recombination appears to be one of the factors driving the emergence of new viral strains.

Human rabies: prospects for elimination

Almost half of all countries in the world are effectively free of human deaths from dog-mediated rabies. But the disease still affects people in low- and middle-income countries, especially the rural poor, and children. Successful regional elimination of human rabies is attributable to advances in significant and sustained investment in dog vaccination, post-exposure vaccination and surveillance, illustrated by productive efforts to reduce human rabies in Latin America over the last 35 years. Nonetheless, countries still facing endemic rabies face significant barriers to elimination. Using the 2017 Global Strategic Plan to end human rabies deaths from dog-mediated rabies by 2030 as a reference point and an organizing framework, we assess progress toward global rabies elimination by examining the characteristics of successful regional control efforts and barriers to elimination. Although substantive barriers exist for countries where rabies remains endemic, advances in knowledge, technology, institutions, and economics provide a basis for optimism.

Regional and age difference of human rabies prevalence of the past fourteen years in China

OBJECTIVE

The aim of this study is to describe the epidemiological characteristics about regional and age difference of human rabies in the past fourteen years in China, and provide a reliable epidemiology basis for further control and prevention of human rabies.

METHODS

The database of "China Public Health Science Data Center" affiliated Chinese CDC was searched with the key words of "rabies" or "epidemiology" or "morbidity" or "mortality" from 2004 to 2018 and the corresponding data about human rabies cases was collected referred to regional and age difference for describing the epidemiological characteristics of human rabies.

RESULTS

In this study, a total of nearly 26,315 rabies cases (1754 ± 253) and 25,691 rabies-related deaths (1712 ± 255) (Mean ± SE) were reported, and a decreasing trend about the morbidity and mortality of human rabies existed from 0.2039 and 0.2039 (1/100,000) in 2004 to 0.0304 and 0.0295 in 2018. Otherwise, regional difference of human rabies prevalence significantly existed, and juvenile and middle-aged population especially in 50-60 years old were more easily attacked and infected with rabies (all p < 0.05).

CONCLUSION

This study proved that human rabies still is a major public health problem in China though a decreasing trend about the morbidity and mortality of human rabies existed in the past fourteen years.