OVERVIEW
Enterovirus 71, or EV71 for short, is one of the major pathogens causing hand, foot, and mouth disease (HFMD) in infants and young children.EV71 was first isolated from fecal specimens of infants with central nervous system disease in California in 1969 and was identified and named in 1974. Since then, the prevalence of EV71 has been reported in many countries. The first discovery of EV71 infection in mainland China was made in the winter of 1987, and subsequent outbreaks have been attributed to EV71 infection.
Etiology
Enterovirus 71 is a heat- and acid-resistant microRNA virus that is pathogenic to suckling mice and causes myositis similar to that caused by coxsackie group A viruses. Oral or injectable infection in rhesus monkeys produces a disease similar to poliomyelitis. Neurotoxicity in monkeys appeared to be related to the ability of the virus to replicate at high temperatures, but oligonucleotide electrophoresis and gel electrophoresis separation of the viral proteins failed to differentiate between non-neurotoxic strains. The virus is excreted from the patient’s nasopharyngeal secretions and feces, and the disease develops via oral infection, primarily through close contact.
Symptoms
Enterovirus 71 infection can cause a variety of clinical manifestations. In Australia, Sweden, and Japan, the main manifestations are hand, foot, and oral diseases, which usually occur after a 1- to 3-day prodromal fever, and no severe central nervous system disease has been observed. In contrast, in the 1975 epidemic of enterovirus 71 in Bulgaria, aseptic meningitis predominated, with 21% of cases presenting with acute paralysis similar to poliomyelitis. The disease progressed rapidly, with paralysis occurring 10 to 30 hours after onset. About half of the cases present with encephalitis or cerebral nerve damage (medullary palsy). Hand, foot, and mouth disease and severe CNS infection have been observed in the same epidemics of enterovirus 71 in Rochester and New York in the United States and in small epidemic outbreaks in Japan and Hong Kong.
Other less common clinical manifestations include generalized maculopapular rash, myocarditis, infectious polyneuritis, and epiglottitis.
Screening
Enterovirus 71 can be isolated from a variety of clinical specimens, including herpes fluid, feces, oropharyngeal secretions, urine, and cerebrospinal fluid, with herpes fluid having the highest rate of isolation and cerebrospinal fluid the lowest, and serum-specific antibody testing aiding in the diagnosis.
In patients with severe cerebral nerve damage, EEG abnormalities may be present.
Diagnosis
Diagnosis is confirmed on the basis of clinical presentation, epidemiologic trends, and laboratory tests for virus isolation and serology.
Treatment
Antiviral and symptomatic treatment. At present, except for poliovirus, for which there is a vaccine, there is no special treatment for enteroviral infections. Therefore, only supportive therapies can be adopted in the treatment of uncomplicated patients, and when there are complications, it is recommended to avoid large amounts of intravenous fluids and give priority to drugs to enhance cardiac output and lower cerebral blood pressure in consideration of the fact that acute deterioration of severe cases is mainly related to cardiac failure.
Prevention
1. Local isolation and avoidance of contact
Early detection of the source of infection, all children found to have signs of HFMD should not be sent to nurseries and kindergartens; isolation for treatment, separate food and accommodation, utensils and toys should be separated; to avoid infecting other children.
2. Keep the disease from entering through the mouth and prevent close contact.
EV71 infection is mainly spread through close contact with food and objects contaminated by saliva, herpes fluid and feces, and both children and adults can be infected. Avoid contaminating water and food with feces, nasal and oral secretions, handle children’s feces and excretions thoroughly, wash and disinfect diapers before use, and disinfect children’s bottles and eating utensils frequently.
3. Develop hygienic habits
Teach children and students to develop hygienic habits from childhood, to break the habit of sucking fingers, to stay away from garbage and unclean environments, and to wash their hands thoroughly after playing games, before meals, and after going to the toilet. Adults who are infected with the disease have no symptoms and become a hidden source of infection, which is even more dangerous.
4. Strengthen environmental hygiene
The environment and toys of childcare institutions and public swimming pools must be strictly sterilized. Pay attention to the harmless disposal of feces and never allow contaminated water.
Improve the epidemic reporting system. Anyone with fever, cold or respiratory symptoms, or children found with herpes rash of hand, foot and mouth should go to the hospital as soon as possible.
5. Pay attention to hygiene and keep away from viruses
Parents of children under the age of 15 should be vigilant and take precautionary measures during the coming peak season of enterovirus epidemic (June to September).
6. Enhance immunity against viruses
In addition to staying away from viruses during the epidemic season, it is also necessary to strengthen our natural immunity to fight against viruses. This requires us to increase the intake of fresh vegetables and fruits.