Re-emergence of canine influenza in the United States of America; a call for One Health approach; a letter to the editor

Abstract

Dear Editor, The heterogeneity of zoonotic canine influenza viruses (CIVs) through genetic reassortment as well as the point mutations typical of RNA viruses and their capacity to cross the species barrier continuously, has always been One Health concern1. This necessitates ongoing animal and human population monitoring1,2 in the human and animal world. Despite a decrease in the prevalence of CIV in the United States of America over the last 5 years, there was a re-emergence in the early periods of February 2023 where it caused serious outbreaks of respiratory illness in dogs in Philadelphia, North Texas, California, and Florida regions of the country3. A recent report in early February 2023 showed that veterinarians, across the United States of America, in these regions witnessed severe cases of canine influenza season3,4. Veterinarians in these regions of the country warned of a severe canine influenza season. They are worried and described the recent scourge of canine influenza as abnormal for them considering the fact that uncomplicated infections with a host-adapted influenza virus tend to be associated with high morbidity and more severe disease3. Increased fatalities may be seen in very young, old, or debilitated animals5. Despite no definitive reports of human infections with CIVs5, there is a possibility of humans contracting the disease, which could cause significant health problems, economic, and financial including mental health problems in them, perhaps due to lots of gaps in One Health measures put place in the control of canine flu in the United States of America. And despite the increasing awareness of the One Health approach, there is a lack of communication and coordination between human health, animal health, and environment sectors6 in the United States of America, which could still limit the implementation of the control of canine flu in the country. Owning to this, we aimed to identify these gaps with possible One Health strategies that would lead to the improvement of quality health care services and increase resource efficiency in optimizing preventive and control programs on Canine influenza in the United States of America. The prevalence of Canine Flu is quite rare worldwide6. Although, avian A(H3N8) influenza viruses found in wild birds can spread to a variety of mammalian hosts leading to epidemics in dogs and horses in many countries worldwide7,8. Canine influenza mostly affects dogs, but can also affect cats9. Historically, the H3N8 strain of the CIV was originally identified in the year 2004 in greyhounds in Florida but has subsequently been found in countries like; Nigeria, Canada, the United Kingdom, Australia, and China. A new strain of the H3N2 flu virus was first identified in dogs in China and South Korea back in 2006, which then gradually spread across Southeast Asia, including America, and became endemic10–12. Despite a decrease in the prevalence of CIV in the United States over the last 5 years, there was a re-emergence in the year 2015 when it caused serious outbreaks of respiratory illness in dogs in the United States, especially in Philadelphia13,14. This re-emergence may have been linked to the importation of dogs rescued from meat markets in Asia15,16. Since then, the H3N8 CIV has been occurring in isolated instances in most states in the United States, having an intermittent or uneven pattern of distribution in the United States5. As of December 2021, outbreaks caused by the H3N2 CIV were also confirmed in Korea, China, Thailand, Canada, and again the United States5. Thus, the re-emergence of CIV in the United States, particularly in Philadelphia, North Texas, California, and Florida witnessed again in the year 2023 is not so surprising. Philadelphia alone is known as a region to be in the midst of an unusual outbreak of canine influenza. This recent outbreak of canine flu was noticed by the local veterinarians in Philadelphia, North Texas, California, and Florida, and revealed a trend of dogs tested positive in the early periods of February 20233,4. CIVs are considered to be part of a diverse group of viruses and bacteria. These viral and or bacterial agents tend to cause a syndrome known as a canine infectious respiratory disease complex, otherwise known as infectious tracheobronchitis or kennel cough5. It has 8 segments, which code for more than 15 viral proteins17. CIVs belong to the species influenza A virus, genus Alpha-influenza virus, and family Orthomyxoviridae17. These viruses are large groups of highly variable viruses that are adapted to circulate in particular hosts, but can occasionally infect other animals13. Most influenza A viruses are maintained in birds (avian influenza viruses), but a few circulate in mammals including people—human influenza A viruses), pigs—swine influenza viruses, and horses—equine influenza viruses. Also, additional viruses circulate in bats, but they do not seem to be transmitted to or from other species. On a few occasions, influenza viruses can adapt to a new host species, either “whole” or after reassorting with another influenza virus5. The mode of transmission of mammalian influenza viruses is usually through droplets and aerosols initiated by coughing and sneezing, and by contact with nasal discharges, either directly or through fomites5. The mode of transmission is favored through close contact and closed environments. The reservoir for the virus has been found in the respiratory secretions of both symptomatic and subclinically infected dogs. Although, experimental studies also showed a reservoir of the virus in cats and experimentally infected ferrets5. The incubation period for H3N8 canine influenza is approximately between 2 and 3 days, even though some studies argued that it could range from about 1 to 5 days. The greatest risk of infection is among dogs that live in kennels or are exposed to transient dog populations, for example, in animal shelters, dog training classes, or dog daycare facilities. Although, seroprevalence in household pets is <5%. During an outbreak among naive animals, the infection rate in a facility may approach 100% within days, and clinical signs in 60%–80% of the dogs is usual5. CIV usually results in minor respiratory symptoms in dogs, such as coughing, sneezing, nasal discharge, eye discharge, as well as a loss of appetite. It is a highly contagious virus that can mimic symptoms of “kennel cough”—dry cough. However, it can also cause severe symptoms, such as a high fever and pneumonia. Although, many dogs recover fully without complications. Secondary bacterial infections can exacerbate the clinical signs, and prolong recovery resulting in complications, such as pneumonia13. Other common clinical features include nasal discharge, sneezing, ocular discharge, lethargy, and loss of appetite, whereas diarrhea and/or vomiting have been reported infrequently. The canine influenza outbreak has negatively impacted the populations of the United States of America in many ways4,15. Firstly, in the area of economy. The vaccine for CIV is not free. According to research, the cost of treating canine influenza ranges from $20 to $55 anywhere in the United States of America15. Because of this, an individual might have to pay more depending on the veterinary office policy. However, regardless of the exact cost, it is likely that the expense of treating and preventing canine influenza will have a negative impact on the U.S. population’s economic well-being17. Secondly, having a pet could help the mental health of individuals. In the United States of America, 74% of pet owners say their mental health improved because of animals. Due to the recent outbreak of canine influenza in Philadelphia, for example, there is a likelihood of negative impacts on the mental health of pet owners in the city4. For many individuals, their pets play an important role in their mental health, providing companionship, emotional support, and a source of stress relief. However, if their pets become sick with CIV, this can lead to worry, anxiety, and stress for their owners. In addition, there is an increased demand for veterinary care in the United States of America, especially in Philadelphia4. Due to the high number of influenza cases in the region, there has been an increase in demand for care for dogs, which in turn leads to increased strain on veterinary clinics4. One Health, being a collaborative, multisectoral, and transdisciplinary approach, involves working at the local, national, regional, and global level with the aim of achieving optimal health outcomes that recognize the interconnection among people, animals, plants, and their shared environment6. One Health expands the scope of comparative medicine to surveillance in animals and the environment for early disease detection and a better understanding of threats to mitigate risk18. The growth in support for the One Health concept has led to the establishment of several global initiatives to adopt and advance a One Health approach to addressing global health threats19. Though no human infections with CIVs have been reported to date20, existing collaborative protocols among all the health care providers in the United States of America, and the international communities, as well as non-governmental organizations, should be the focal point in the event of outbreaks of novel influenza A viruses. As these are necessary and important to be followed in the event of an outbreak of canine influenza with suspected human infections. Influenza viruses normally spread most readily when susceptible animals are in close contact. Infection control measures are similar to those used for other contagious respiratory diseases and include the isolation of infected animals5. We urge the U.S. government to implement One Health policy control about the CIV, such as cleaning and disinfection of cages, bowls, and other fomites including hygiene measures and hand washing. Clothing should be cleaned by washing it with detergent at normal laundry temperatures. Some researchers found that a 21-day isolation period seemed to result in better control of the H3N2 virus, which may be shed for prolonged periods, than either 7 or 14 days. A 28-day quarantine should be employed during outbreaks in the United States of America as it was done too in Canada5. A number of outbreaks of canine flu in Mexico, Panama, Jamaica, and Cuba have been associated with imported dogs, particularly rescue dogs from Asia5. We urge the U.S. government to improve screening and quarantines of dogs and cats in the country, most especially in Philadelphia, Texas, California, Florida, and North Texas4. The health authorities in the United States of America should work hand-in-hand with the Centers for Disease Control including the World Health Organization, the Food and Agriculture Organization of the United Nations, the World Organization for Animal Health (OIE), which are commonly known as the Tripartite organizations21 in conducting a risk assessment on the pandemic potential of CIVs using the Influenza Risk Assessment Tool. The U.S. government should also work with the local farmers and hunters in the country by educating them more about CIV, especially on how they can protect their dogs and cats through vaccination. A practical example of how the One Health approach can help in mitigating canine influenza is the vaccination of dogs with Nobivac Canine Flu Bivalent22, which reduces the exposure of at-risk dogs, vaccination may not altogether prevent an infection, but it may reduce the severity and duration of clinical illness in dogs, this will tremendously reduce the risk of animal to human transfer in cases of human infection with canine influenza23. As done in South Korea China and parts of Honduras and Mexico5, Canine influenza vaccines should be licensed for both H3N8 and H3N2 canine influenza in the areas affected in the United States of America by the U.S. government. Controlling canine Influenza in the United States of America requires early detection before it becomes a major problem and consequently, more difficult to control in the country. While prevention is still the first line of defense against zoonoses and other infectious diseases, systematic and sentinel surveillance at the animal-human interface can support the early detection of a new strain capable of infecting humans23. Surveillance system for zoonotic diseases coordinated through a data-driven One Health approach should, therefore, be used to project the disease progression and predict as accurately as possible the magnitude and time of a potential outbreak, based on a range of mathematical model assumptions and an understanding of pathogen transmission dynamics18. Overall, there is a need for more mass awareness campaigns by the health authorities in the United States of America about canine flu among the U.S. populations and the world at large, especially on its early signs and symptoms, wide vaccination coverage against the disease, especially for pet owners, local farmers, and hunters in the country. Veterinary doctors, physicians, nurses, pharmacists, including psychologists, social welfare officers, and other para-medical health workers, as well as the medical and para-medical students in the United States of America and the world at large should work together in conducting more research about CIV, as well as holding more regional and international conferences about CIV for more updates and in finding a long-lasting solution for the disease. Ethical approval Not Applicable. Sources of funding None. Author contributions M.O.O.: conceptualization of ideas, manuscript preparation, and data curation. M.O.O., P.N.W., H.A.A., B.J., A.Z.Z., and R.S.G.: writing of initial drafts and critical review and comments. P.N.W.: administrative supports. Conflicts of interest disclosures The authors declare that they have no financial conflict of interest with regard to the content of this report. Research registration unique identifying number (UIN) Not applicable. Guarantor Malik Olatunde Oduoye.