Update on hand-foot-and-mouth disease
Section snippets
Epidemiology
HFMD and herpangina are common childhood illnesses, most typically noted in children younger than 10 years old.1 Cases are uncommon in adults, possibly stemming from cross-immunity from other enteroviruses and immunologic memory from childhood infections.5 Epidemics are common in Asia, occurring in China, Taiwan, Japan, Vietnam, South Korea, and Malaysia.1 One series of 157,707 cases of HFMD noted that 97% of patients were 0 to 9 years of age, with the highest proportion in the 0 to 4 year age
Clinical features: Systemic
The range of internal or generalized symptomatology is quite broad in humans and includes asymptomatic infection and benign low-grade illness (Table 1). Most cases of HFMD do not have associated internal findings other than fever, malaise, and herpangina (Figure 1). Compared with CVA16, EV71 is more likely to produce a more severe clinical picture with patients more likely to develop a high fever (> 39°C) with prolonged fever (> 3 days).[1], [18] Additionally, EV71 (and recently EV68) infection
Clinical features: Mucocutaneous
Cutaneous features of HFMD include classic findings such as papules, small vesicles, and erosive lesions of the palms, soles, distal extremities (Figure 2), and buttocks, leading some to call the disease hand-foot-mouth-and “butt” disease (Table 2). Additionally, HFMD exhibits ulcerations of the buccal and pharyngeal mucosa. Herpangina (Figure 1) refers to fever and ulcerations on the pharyngeal and mucosal surfaces without any papulovesicular eruption on the skin. Although the presence of
Clinical testing
Typical HFMD presents with such a classic appearance that many cases are not brought to the attention of a dermatologist, much less requiring viral testing; however, atypical forms, most recently due to the CVA6 subtype, can have variable and unusual cutaneous manifestations and may be mistaken for other inflammatory or infectious etiologies. Standard viral cultures are ineffective in detecting the virus, with one studying noting that culture detected only 14-16% of samples that tested positive
Mechanism of virulence
Following spread to the pharynx and gastrointestinal tract, the virus is spread to local lymph nodes. Minor and major viremia then occur with a variable duration and age dependency.22 Primary viremia tends to be longer in children younger than 2 years of age as opposed to older patients. Secondary viremia occurs after viral reproduction in various regions of the body, such as mucous membranes, and skin, plus nervous and cardiac tissue, producing clinical signs and symptoms. Table 3 briefly
Treatment and future directions
Given the self-limited nature of most cases of HFMD, supportive care is ideal for the management of patients with hand-foot-and-mouth disease, including maintenance of hydration and pain control. Secondary infection rarely occurs, unlike the situation with other exanthems such as varicella, which manifest with increased vulnerability to bacterial infections (especially group A streptococcus) secondary to depressed T-cell immunity.[5], [40] Additionally, isolation and observation of vulnerable
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