The Vietnam Initiative on Zoonotic Infections (VIZIONS): A Strategic Approach to Studying Emerging Zoonotic Infectious Diseases

Abstract

The effect of newly emerging or re-emerging infectious diseases of zoonotic origin in human populations can be potentially catastrophic, and large-scale investigations of such diseases are highly challenging. The monitoring of emergence events is subject to ascertainment bias, whether at the level of species discovery, emerging disease events, or disease outbreaks in human populations. Disease surveillance is generally performed post hoc, driven by a response to recent events and by the availability of detection and identification technologies. Additionally, the inventory of pathogens that exist in mammalian and other reservoirs is incomplete, and identifying those with the potential to cause disease in humans is rarely possible in advance. A major step in understanding the burden and diversity of zoonotic infections, the local behavioral and demographic risks of infection, and the risk of emergence of these pathogens in human populations is to establish surveillance networks in populations that maintain regular contact with diverse animal populations, and to simultaneously characterize pathogen diversity in human and animal populations. Vietnam has been an epicenter of disease emergence over the last decade, and practices at the human/animal interface may facilitate the likelihood of spillover of zoonotic pathogens into humans. To tackle the scientific issues surrounding the origins and emergence of zoonotic infections in Vietnam, we have established The Vietnam Initiative on Zoonotic Infections (VIZIONS). This countrywide project, in which several international institutions collaborate with Vietnamese organizations, is combining clinical data, epidemiology, high-throughput sequencing, and social sciences to address relevant one-health questions. Here, we describe the primary aims of the project, the infrastructure established to address our scientific questions, and the current status of the project. Our principal objective is to develop an integrated approach to the surveillance of pathogens circulating in both human and animal populations and assess how frequently they are exchanged. This infrastructure will facilitate systematic investigations of pathogen ecology and evolution, enhance understanding of viral cross-species transmission events, and identify relevant risk factors and drivers of zoonotic disease emergence.

Keywords: Vietnam; diagnostics; disease surveillance; diseases of unknown origin; genomics; high-risk cohort; social science; ultra-deep sequencing; zoonotic infection.

Figure 1

The structure of the VIZIONS project across Vietnam. Map of Vietnam showing the main components of VIZIONS, these are (1) hospital-based surveillance program studying respiratory tract infections, central nervous system infections (CNS), enteric infections, and jaundice for detailed clinical and epidemiological investigation; in Dong Thap, Ho Chi Minh City, Dak Lak, Khanh Hoa, Hue, Hanoi, and Ba Vi (small white circles) and (2) a longitudinal cohort study of occupational risk of zoonotic infections, plus records of risk behaviors, with linked sampling of putative animal reservoirs that will generate >50,000 specimens for molecular investigation being performed in Dong Thap, Dak Lak, Khanh Hoa, and Ba Vi (large pink circles).

Figure 2

Diarrheal disease at Dong Thap Provincial Hospital, 2007–2014. a Hospital case data showing the number of hospital visits (outpatient and inpatient) for diarrheal disease under the three most common ICD-10 codes used in this hospital (representing 99.4% of all diarrheal disease records) from January 2007 to April 2014. Red indicates cases classified under ICD-10 code A04 (other bacterial intestinal infections), yellow indicates cases classified as A08 (viral and other specified intestinal infections), and blue indicates cases classified as A09 (diarrhea and gastroenteritis of presumed infectious origin). The dashed line shows the initiation of VIZIONS hospital surveillance in Dong Thap Provincial Hospital, November 2012. b Number of viruses detected in diarrheal disease samples collected under VIZIONS protocols from November 2012 through April 2014. Screening included RT-PCR for the listed panel of viral pathogens, as well as standard microbiological culture (data not shown). A diarrheal disease DUO is designated as a sample in which no pathogen was detected by the aforementioned screening methods.

Figure 3

The VIZIONS high-risk cohort in Dong Thap, Dak Lak, and Ba Vi. The second major operational component of VIZIONS is sampling a high-risk cohort of people that may be likely to be hosts of zoonotic pathogen transfer as a consequence of occupational exposure to animals. This component of the study is being performed in three locations (Dong Thap, Dak Lak, and Ba Vi). These photographs outline some of the main activities and locations related to this cohort. a Responsive animal sampling with the sub-department of animal health in Dong Thap province, b Market workers cleaning poultry in Dak Lak province, c Rats prepared for human consumption in Dong Thap province, d A restaurant worker butchering bamboo rat meat in Dak Lak province, e Sampling a child enrolled in the cohort study on a farm in Dong Thap province, and f Butchered porcupine feet prepared for consumption in Dak Lak province.