1, hand, foot and mouth disease epidemic characteristics and new situation
1.1 Progress in pathogenic research
EV71 and CVA16 are the most common pathogens causing HFMD, other coxsackieviruses such as A5, A7, A9, A10, B3 and B5 can also be caused, but EV71 has been reported in more studies in China. EV71 can be divided into genotypes A, B and C, and genotypes B and C can be subdivided into B1 to B4 and C1 to C4 genotypes. Since 1989, many scholars in China have isolated EV71 from patients with HFMD in Hubei, Shenzhen, Shanghai, Chongqing, Guangzhou, and Fujian.
Among them, Li et al. conducted genetic characterization of the sequences of EV71 prevalent in Shenzhen, China, from 1999 to 2004, as well as the sequences of EV71 prevalent strains in other regions of mainland China, and determined that they were all of the C4 genotype. This genotype is consistent with the genotypes of the strains prevalent in Fuyang, Shenzhen, Chongqing, Shanghai and Taiwan in China in 2004, and is relatively close to each other. A recent study in Xinxiang region showed that EV71 virus in this region belongs to C4a subtype, which is close to the representative strain in Fuyang, Anhui province in 2008.
EV71 is genetically diverse, and the epidemics of different genotypes of EV71 are temporal and regional, and the virus can evolve in the same region. several large epidemics of HFMD in Singapore, Malaysia, Korea, Australia and Taiwan Province of China in 1998-2001 were caused by multiple genotypes of EV71, including B1, B3, B4, C2, C3, etc. After 2005, the epidemic strain of EV71 in mainland China was the C4 gene subtype C4a cluster.
The epidemic strain of EV71 in Taiwan Province of China was subtype B1 in 1980 and 1986, C2 in 1998, B4 from l999 to 2003, and C4 in 2004. the alternating prevalence of different genotypes indicates that EV71 evolution is active.
1.2 Infected population and its changes
Hand, foot and mouth disease is a common acute infectious disease, which is classified as a category C infectious disease in China. It mostly occurs in preschool children, and the susceptible population of HFMD is children under 10 years old, among which children under 5 years old are the most common, especially the highest incidence in the age group under 3 years old, and can occur epidemically in kindergartens. The conventional wisdom is that adults are generally immune to HFMD virus and that it rarely occurs in adults. However, with the development of the epidemic, the population infected with HFMD has changed.
Early on, some scholars believed that adults with immunodeficiency or low immunity could be infected with the disease. In recent years, however, there has been a significant increase in the number of adults with HFMD. 2008 to date, more than 100 cases of HFMD in adults have been reported in China, all without immunodeficiency or obvious immunocompromised manifestations and with severe cases of combined encephalitis, orchitis and other diseases. In addition, a recent study by the author on the follow-up of family members of HFMD patients found that there were not only adult patients in the families of children with HFMD, but also adult patients with occult infection.
The presence of adult HFMD patients and adult recessive infections may be one of the main reasons why HFMD outbreaks are difficult to control and cause major outbreaks.
1.3 Clinical manifestations
HFMD is clinically characterized by fever, oral ulcers and herpes as the main symptoms, starting mostly with prodromal symptoms such as low fever, malaise and loss of appetite. Hand, foot and mouth disease lesions are initially red papules, which soon develop into herpes, surrounded by a red halo, commonly found on the palms of the hands and soles of the feet, also seen on the buttocks. Oral herpes is common on the tongue, gums, and buccal mucosa of the mouth and starts as a small red rash that often turns into an ulcer.
Some patients have only a rash or oral ulcers. Individual patients may have complications such as myocarditis, pulmonary edema, aseptic meningitis, and meningoencephalitis. Adult HFMD generally has mild systemic symptoms, mostly consisting of hand and foot rashes and/or oral ulcers, and is rarely accompanied by systemic damage.
1.4 Transmission routes
HFMD is an infectious disease, and both patients and latently infected persons can serve as the source of infection for the disease, but it is not transmitted between humans and animals. The incubation period from infection to the appearance of symptoms is usually 3 to 6 days. The virus that causes HFMD is present in the herpes fluid, pharynx, and feces of patients, and can be contracted through saliva, droplets, feces, herpes fluid, and other excretions via the respiratory and digestive tracts, and can infect healthy children and adults.
Water and food contamination is another major cause of HFMD epidemics. The virus discharged by the infected person contaminates the water source, and the contaminated water source further becomes a source of contaminated food or other substances, which can cause small outbreaks of HFMD epidemics. Some studies have shown that adults with HFMD are mostly infected through transmission from affected children, i.e., intra-family transmission.
Infected adults have a large range of activities, carry a large amount of virus, and can infect other children and adults, and the ability to spread and harm far more than child patients, so adult patients and hidden infections should cause us to pay great attention.
2 .Hand, foot and mouth disease prevention and new insights
2.1 Change awareness and strengthen surveillance Strengthening surveillance and good epidemic reporting is the key to controlling the epidemic of HFMD. Each province and city disease prevention and control center should improve the epidemic reporting system in a timely manner, discover HFMD patients at the first time, and take prompt measures to isolate patients effectively to prevent the spread of the disease so as not to cause a widespread epidemic and social panic.
Epidemiological case investigations should also be actively carried out to allow effective statistics and monitoring of the number of HFMD cases and illnesses. Pharyngeal swabs or stool specimens should be collected for testing in seriously ill patients and special patients to provide a full understanding of the possible mutations of the disease and thus serve as an effective early warning. Change the understanding of HFMD in adults. Although adult patients have mild symptoms, they are highly contagious and socially harmful far more than pediatric patients. Pay high attention to the reporting, investigation and isolation of HFMD in adults in order to do a comprehensive surveillance of HFMD.
2.2 Cut off the transmission route early Hand, foot and mouth disease often occurs in early childhood care institutions. Early childhood care institutions should strictly implement the morning check system, which should not be limited to children, but also include parents and teachers of early childhood care institutions who pick up children. The suspected cases of children or parents with suspected symptoms should be isolated in time to control the spread of the disease in child care institutions.
During the epidemic period, child care institutions should wash and disinfect toys and utensils daily and disinfect contaminated daily items and eating utensils at the end of the day to reduce indirect contact transmission. Child care institutions should open windows more often to keep indoor air circulation, dry clothes regularly, and urge children to wash their hands regularly before and after meals.
2.3 Improve in-hospital prevention mechanism During the epidemic of HFMD, hospitals need to set up special outpatient clinics and treatment rooms to receive HFMD patients in order to avoid nosocomial infection and cross-infection. When medical institutions find hand, foot and mouth cases, they should report to the local health prevention and control department at the first time, and carefully examine the patients and their close contacts to clarify the pathogenic diagnosis early and take comprehensive prevention and control measures to prevent the spread of the epidemic.
Focus on strengthening the disinfection of obstetrics and pediatric wards in hospitals, and all utensils used by nursing staff in the care process should be disinfected in a timely manner. Seriously ill patients should be treated in isolation, and all bedding and toiletries used by patients should be disinfected in a timely manner. In addition, parents of affected children should also be carefully examined, and if conditions permit, they may be advised to perform pathogenic examinations to exclude adult HFMD and those with occult infection. Once positive cases are found, they should be reported and isolated in time to achieve thorough prevention in the hospital.
2.4 Strengthen family preventive measures Hand, foot and mouth disease is transmitted in many ways, parents should be reminded to take their children to crowded public places as little as possible, especially those with poor air circulation, to reduce the chance of being infected. Parents should also guide their children to develop good hand-washing habits, and do not let children drink raw water and eat cold food in summer.
Once diagnosed, children and adults, especially the elderly, pregnant women and the immunocompromised, should avoid close contact (e.g. kissing, hugging, sharing utensils, etc.) with HFMD patients during the onset of the disease, and even family members and people living with the patient for a long time should avoid close contact with each other to cut off the spread of the hidden infection.
In conclusion, with the development of the epidemic, HFMD has changed to different degrees in terms of pathogens, infected populations, clinical manifestations and transmission routes, which brings new challenges to the prevention and control of the disease. The presence of adult patients with HFMD and occult infections forces the traditional prevention and control strategy to be updated urgently, and the attention and prevention of adult patients and occult infections should be incorporated into the new HFMD prevention and control strategy to improve the prevention and control of HFMD.