Water Research: Review of Influenza Virus in Water Environments Across Human, Poultry, and Wild Bird Habitats

Long Distance Migratory Flyways - Credit USGS

#17,892

Our knowledge of how influenza viruses persist in the environment continues to expand, and we now understand that under the right circumstances these viruses can sometimes survive for extended periods of time outside of a living host. 

We're not talking hours, but days, weeks, or sometimes even months.  

How and where this happens could assist a flu virus in spreading geographically, in spilling over into a new host species, or even facilitate the creation of a novel reassortment.  

• Over the past dozen years we've seen number of studies investigating long-distance airborne spread of avian flu, including 2019's Nature: Airborne Transmission May Have Played A Role In Spread Of U.S. 2015 HPAI Epizootic and 2022's HPAI (H5N8) Clade 2.3.4.4b Virus in Dust Samples from Poultry Farms, France, 2021. 

• In 2020 - in Proc. Royal Society B: Influenza A Viruses Remain Viable For Months In Northern Wetlands - USGS - researchers from the USGS documented long-term survival of influenza A viruses in wetlands in both Alaska and Minnesota, suggesting theses waters could potentially serve as an over-wintering environment for for AI viruses

• And we've looked at a number of studies (see here, here, here, and here) on the impact of partial or incomplete processing of effluent at WTPs (wastewater treatment plants) on everything from the spread of viruses and bacteria, to the creation of antiviral and antibiotic resistant organisms. 

Today we've a systematic review of the literature on the spread and viability of influenza viruses via various water environments.  By nature, these reviews are lengthy, so I've just posted the Abstract and a few excerpts. 

Follow the link to read it in its entirety. I'll have a brief postscript after the break.

A systematic review of influenza virus in water environments across human, poultry, and wild bird habitats

S Kenmoe a, GR Takuissu b, JT Ebogo-Belobo c, C Kengne-Ndé d, DS Mbaga e, A Bowo-Ngandji e, JL Ondigui Ndzie e, R Kenfack-Momo f, S Tchatchouang g, R Lontuo Fogang h, E Zeuko'o Menkem i, GI Kame-Ngasse c, JN Magoudjou-Pekam f, S Puzelli j, L Lucentini k, C Veneri k, P Mancini k, G Bonanno Ferraro k, M Iaconelli k, C Del Giudice k…G La Rosa kShow  

https://doi.org/10.1016/j.wroa.2023.100210 

Under a Creative Commons license

 

Highlights

• This study aimed to assess influenza prevalence in different water environments.

• Prevalence of influenza A within poultry habitats: 4.3 % to 76.4 %.

• Prevalence of influenza A in migratory wild birds habitat: 0.4 % to 69.8 %.

• Geographically: Americas 39 %, Europe 19 %, South-East Asia 2 %, Western Pacific 39 %.

• Different influenza A subtypes found in poultry and wild bird habitats.

Abstract

Influenza, a highly contagious acute respiratory disease, remains a major global health concern. This study aimed to comprehensively assess the prevalence of influenza virus in different aquatic environments.

Using 43 articles from four databases, we thoroughly examined water matrices from wastewater treatment plants (WTPs) and other human environments, as well as poultry habitats and areas frequented by migratory wild birds.

In WTP influents (10 studies), positivity rates for influenza A ranged from 0.0 % to 97.6 %. For influenza B (8 studies), most studies reported no positivity, except for three studies reporting detection in 0.8 %, 5.6 %, and 46.9 % of samples. Within poultry habitats (13 studies), the prevalence of influenza A ranged from 4.3 % to 76.4 %, while in environments frequented by migratory wild birds (11 studies), it ranged from 0.4 % to 69.8 %. Geographically, the studies were distributed as follows: 39.5 % from the Americas, 18.6 % from Europe, 2.3 % from South-East Asia and 39.5 % from the Western Pacific.

Several influenza A subtypes were found in water matrices, including avian influenza (H3N6, H3N8, H4N1, H4N2, H4N6, H4N8, H5N1, H5N8, H6N2, H6N6, H7N9, H0N8, and H11N9) and seasonal human influenza (H1N1 and H3N2). The existing literature indicates a crucial requirement for more extensive future research on this topic. Specifically, it emphasizes the need for method harmonization and delves into areas deserving of in-depth research, such as water matrices pertaining to pig farming and prevalence studies in low-income countries.

Graphical abstract

(SNIP)

The limited number of studies, as evidenced by the 43 identified in this review, underscores the pressing need for more comprehensive data to gain a nuanced understanding of the issue. In the context of the influenza virus, which possesses pandemic potential, it is imperative not to overlook any potential transmission pathways. Therefore, we advocate for a concerted effort to expand the scope and depth of data collection in order to better grasp the dynamics of influenza virus presence in various water environments. A more extensive dataset will not only contribute to a more robust understanding of the ecological aspects of influenza transmission but also play a crucial role in informing preventive strategies to mitigate potential pandemic threats.

Although this study provides valuable insights into the prevalence of influenza viruses in water environments, several limitations should be acknowledged. The paucity of studies in certain regions and water sources, coupled with the limited sample size in certain research efforts, limits the generalisability of the findings. To address these limitations, future research should prioritise larger sample sizes and more extensive geographical coverage.

Conclusion

• •

  This study underscores the worldwide significance of influenza surveillance in aquatic environments, encompassing wastewater, poultry settings, and habitats frequented by migratory wild birds.

• •

  Despite an extensive search, no studies on influenza in water environments associated with pigs were found, underscoring the need for future research in this area.

• •

  The review highlights the need for standardized analytical approaches and further research in under-represented regions and water sources.

• •

  In conclusion, this review offers valuable insights into the prevalence of influenza in aquatic environments and emphasizes the importance of continuous research and surveillance. This will enhance our understanding of disease epidemiology and inform global public health strategies.

While the transfer of avian influenza viruses from contaminated waters to other migratory birds passing through is the primary concern, birds aren't the only potential recipients.

• In 2019's Nature: Semiaquatic Mammals As Intermediate Hosts For Avian Influenza, we looked at a study that warned that mink - and possibly other semiaquatic mammals (like raccoons, otters, etc.) - could be at risk of infection as well.

• And more recently, one of the possible explanations offered for the mass mortality of marine mammals from HPAI H5N1 has been environmental transmission of shed virus, as opposed to predation or mammal-to-mammal transmission.

• In 2013 a report (and a study) from UC Davis showed the human 2009 pandemic H1N1 virus had jumped to wild California Elephant Seals just one year after that virus emerged (see The 2009 H1N1 Virus Expands Its Host Range (Again)).

Our shared ecosystem is far more complex and interconnected than most people realize, and it offers emerging pathogens a myriad of ways to blindside our society with the next global health crisis. 

We underestimate it at our considerable peril.