Non-polio enteroviruses typically cause mild illness, such as fever, respiratory symptoms, skin rash, mouth blisters, or body or muscle aches. Some infections can result in more severe complications affecting the brain, heart, as well as nervous system including acute flaccid paralysis (AFP) which is a sudden onset of weakness in one or more limbs. Acute flaccid myelitis (AFM) is a type of AFP that requires specific findings on diagnostic tests.
There are about 100 serotypes of non-polio enteroviruses. Two serotypes that have received recent attention because of possible associations with AFM/AFP are:
Enterovirus D68 (EV-D68) is a serotype that causes respiratory illness. Symptoms range from a mild cold-like illness with coughing and wheezing to severe respiratory infections that require hospitalization. In 2014, an increase in AFP occurred at the same time as a national outbreak of EV-D68-associated respiratory infections and EV-D68 was found in respiratory specimens of some patients with AFP.
Enterovirus A71 (EV-A71) is another serotype that typically causes no symptoms, or can cause hand, foot and mouth disease; however, rarely it has also been associated with severe neurological disease, including AFM as occurred in a recent outbreak in Colorado.
In October 2018, the Centers for Disease Control and Prevention (CDC) issued a health advisory regarding their investigation into an increase in reported cases of acute flaccid myelitis (AFM) in children under 18 years of age across the United States. While case investigations to date have tested for a wide range of causes, and some cases have been associated with enterovirus detections, no pathogen or cause has been consistently associated with these cases of AFM.
This webpage contains information on non-polio enteroviruses, including information on testing for enteroviruses and information on AFP/AFM. Testing for enteroviruses, including EV-D68 and molecular serotyping for other enteroviruses (e.g., EV-A71), is available on request at the laboratory at PHO. For more information on testing, please see section below entitled When is enterovirus testing recommended?
|Information on Enteroviruses|
What are enteroviruses and EV-D68?
Enteroviruses are a group of viruses that can cause a range of symptoms including:
- mild cold-like symptoms
- illnesses with fever and rashes, including hand, foot, and mouth disease
- neurologic problems, (e.g., meningitis, and more rarely, other complications such as AFM/AFP)
- inflammation of the heart muscles (myocarditis) or
- no symptoms at all
Infections with enteroviruses are very common and most people have mild symptoms. There are about 100 types of enteroviruses.
EV-D68 is a specific enterovirus that causes respiratory illness ranging from mild to severe. Symptoms can include a cold-like illness with coughing and wheezing to severe respiratory infections requiring admission to a hospital or possibly to an intensive care unit because of breathing difficulties.
Children and teenagers appear to be at increased risk of infection from EV-D68 because they may lack protection from previous exposures to the virus, although the virus can infect adults as well. Children with asthma seem to have a higher risk for severe respiratory illness.
When do infections from enteroviruses usually occur?
Enteroviruses usually circulate in the late summer and fall, although this can vary depending on the type of enterovirus.
How are enteroviruses spread?
Enteroviruses such as EV-D68 can be present in respiratory secretions from the nose and throat and can spread from an infected person when they cough or sneeze. Touching surfaces or objects contaminated with these secretions may also result in infection if the virus then gets into the body by touching the mouth, nose or eyes. Enteroviruses are also shed from the gastrointestinal tract, and can spread from feces. Spread can also occur by touching infected skin lesions.
What precautions can be taken regarding enteroviruses, including EV-D68?
As with many viral infections, simple precautions can reduce the chances of getting enteroviruses, including EV-D68:
- Clean your hands frequently with soap and water or an alcohol-based hand rub, including after touching commonly touched objects and surfaces, before touching your face, before preparing food and before eating.
- Avoid touching your face as much as possible.
- Stay at least two metres (six feet) away from people who are ill.
- Frequently clean surfaces and objects that are commonly touched.
To avoid spreading viral infections:
- Stay home from work, school and other activities if you are ill.
- Cough and sneeze into your elbow and not your hand.
- Clean your hands frequently with soap and water or an alcohol-based hand rub, including after using the washroom.
People with asthma should ensure that they have their puffers readily available and know how to use them properly. They should also seek medical attention right away if wheezing does not respond to puffers or if you are having difficulty breathing.
Is there a vaccine or specific treatment for non-polio enteroviruses, including EV-D68?
In Canada, there is no vaccine or specific antiviral treatment against non-polio enteroviruses, including EV-D68. Most people don’t require any treatment and will get better on their own, but symptoms like wheezing and fever can be treated (aspirin should be avoided in children). Patients who have difficulty breathing may require hospital admission and those with severe breathing problems may require treatment in an intensive care unit which may involve being placed on a ventilator. Children with weakness in their arms or legs should seek medical attention immediately.
What is the history of EV-D68?
From mid-August 2014 to January 15, 2015 the CDC and state public health laboratories reported a total of 1,153 people with EV-D68, a virus only rarely reported before that time. EV-D68 was primarily identified in children, many of whom had asthma or a history of wheezing. CDC also stated that there were likely millions of individuals with mild EV-D68 infections who did not seek medical care and thus were not tested for the virus. During the late summer and early fall of 2014, several provinces in Canada also reported laboratory-confirmed cases of EV-D68. In both the United States and Canada, an increase in AFM/AFP occurred at the same time as the increase in EV-D68-associated respiratory infections and EV-D68 was found in respiratory specimens of some patients with AFM/AFP. This suggested a possible association between EV-D68 and AFM/AFP. EV-D68 did not appear to circulate to any great extent in 2015. In 2016, there were a few reports of EV-D68 from Ontario and other jurisdictions in Canada, the United States and elsewhere, with a small number of reports of AFM/AFP in children with EV-D68 infection.
The actual number of cases of EV-D68 in Ontario is not known as people with viral infections often don’t seek medical care. As well, when care is sought, swabs to test for viral infections are not routinely done and not all laboratories test for enteroviruses or other respiratory viruses; most laboratories do not test for EVD-68. Furthermore, most respiratory infections, including non-polio enteroviruses, are not reportable to public health authorities unless they are identified as part of an institutional outbreak of respiratory illness, or identified in a reported case of AFP. For most viruses, knowing the specific type of virus does not change patient care.
|Acute Weakness in Children|
What are Acute Flaccid Paralysis and Acute Flaccid Myelitis?
Acute flaccid paralysis (AFP) is a rare but serious clinical syndrome that has many causes, both non-infectious and infectious, including enterovirus infections. AFP is characterized by a sudden onset of weakness or paralysis in one or more parts of the body that occurs without an obvious cause, such as trauma. Acute flaccid myelitis (AFM) is a type of AFP but along with sudden weakness, it requires spinal cord lesions on magnetic resonance imaging for confirmation, or an elevated white cell count in cerebrospinal fluid to be a probable case. In Canada, surveillance is based on AFP, while in the United States it is based on AFM.
Acute Flaccid Paralysis Surveillance in Ontario
Acute flaccid paralysis (AFP) has been reportable in Ontario since 2013. All confirmed cases and cases under investigation for AFP in children under 15 years of age should be reported to public health. Surveillance is conducted as part of global polio eradication to document the absence of poliovirus, which is a rare cause of AFP in areas of the world where polio continues to circulate. Documenting polio-specific investigations, regardless of suspected diagnosis, is one means by which Canada maintains its polio-free status. AFP surveillance can also identify cases of AFP resulting from non-polio enteroviruses. Provincially, between 2014 and 2017, the annual number of reported cases of AFP ranged from a low of three cases in 2015 to a high of 16 cases in 2014 (when there was heightened awareness of reporting due to EV-D68 circulation). AFP is generally felt to be under reported as health care providers may not be aware of this reporting requirement. AFP monitoring for polio surveillance is also conducted by participating paediatricians through the Canadian Paediatric Surveillance Program.
When is enterovirus testing recommended?
Laboratory testing should be considered for patients with severe respiratory illness or neurologic symptoms (e.g., meningitis, AFP/AFM), especially children, among whom symptomatic enterovirus infections, are more common. Testing should also be considered if clusters of severe respiratory illness are identified. Testing is also recommended for patients with suspected viral meningitis/encephalitis or myocarditis. Testing can also be conducted on skin or mucosal lesions in patients with suspected enterovirus illness (e.g., hand, foot and mouth disease), though laboratory testing is not recommended in such patients, who usually experience a self-limiting illness.
What is the enterovirus testing process?
Enterovirus testing, as well as molecular serotyping, including specific EV-D68 detection, is available at PHO Laboratory. Further information on enterovirus testing at available from PHO's laboratory Enterovirus Test Information Sheet.
What testing should be done in someone with acute neurological symptoms?
Persons of any age presenting with AFM, or any child less than 15 years of age with AFP, should have laboratory investigations to detect a viral cause. Screening for viral pathogens may also be indicated for other neurological presentations where viral infection is on the differential diagnosis. Testing should include enterovirus detection, as well as enterovirus molecular serotyping if enterovirus-positive. When submitting specimens from patients with neurological presentation, it is important to document the neurological symptoms on the laboratory requisition form, so the appropriate testing can be ordered. Specimen collection should include:
Collect two sets of stool samples - each stool sample is divided into a sterile container for viral testing and a bacterial (Cary-Blair) transport media container for Campylobacter testing. The clinician should write “Enterovirus / Enterovirus Molecular Serotyping” in the “Test(s) Requested” field of one requisition, and “Campylobacter Testing” in the
“Test(s) Requested” of another requisition.
- Respiratory specimens:
Collect a nasopharyngeal (NP) swab and/or throat swab (NP swab preferred) in universal transport media (UTM), or bronchoalveolar lavage in a sterile dry container. Always submit a throat swab from children under 15 years of age with acute flaccid paralysis. The clinician should write “Enterovirus / Enterovirus Molecular Serotyping" in the “Test(s) Requested” field of the requisition.
- Cerebrospinal Fluid (CSF):
For all ages, collect CSF as appropriate for the investigation. If CSF is collected, the clinician should write “Enterovirus / Enterovirus Molecular Serotyping" in the “Test(s) Requested” field of the requisition.
Note: Clinical specimens from patients of all ages with suspected poliomyelitis, or children under 15 years of age with suspected AFM/AFP, are tested at PHO Laboratory and also forwarded to the National Microbiology Laboratory, Winnipeg, for further investigations.
|Infection Prevention |
and Control Measures
Enteroviruses typically spread by the fecal-oral route; however, EV-D68 appears to spread via droplet and direct contact like other respiratory viruses.
Patients with symptoms of acute respiratory infection should be placed on droplet and contact precautions as per the Annex B: Best Practices for Prevention of Transmission of Acute Respiratory Infection In All Health Care Settings guidance document that outlines risk assessment, hand hygiene, personal protective equipment, control of the environment and administrative controls.
Environmental disinfection of surfaces in healthcare settings should be performed using a hospital-grade disinfectant with a label claim of effectiveness against non-enveloped viruses.
CENTERS FOR DISEASE CONTROL AND PREVENTION
PHO PROVINCIAL INFECTIOUS DISEASES ADVISORY COMMITTEE BEST PRACTICES DOCUMENTS
WORLD HEALTH ORGANIZATION