Because the common enteroviruses, including polio, grow in the intestinal tract and are spread mainly by the fecal–oral route, family outbreaks are usual and the infections are most common among children. A number of echovirus and Coxsackie virus (particularly group A) infections are associated with exanthemata and may be associated with the grayish vesicular lesions of oral herpangina. Pleurodynia, brachial neuritis, pericarditis, and orchitis are characteristic of some cases of group B Coxsackie virus infections and there are certainly other causes. Pain in the back and neck and in the muscles should suggest poliomyelitis or dengue. Lower motor neuron weakness may occur with echo, West Nile, and Coxsackie virus infections, but it is usually mild and transient in nature. The peak incidence of enteroviral infections is in August and September.
Mumps meningitis occurs sporadically throughout the year, but the highest incidence is in late winter and spring. Males are affected three times more frequently than females. Other manifestations of mumps infection— parotitis, orchitis, mastitis, oophoritis, and pancreatitis—may be, but most often are not, present. It should be noted that orchitis is not specific for mumps but occurs occasionally with group B Coxsackie virus infections, infectious mononucleosis, and lymphocytic choriomeningitis. A definite past history of mumps aids in excluding the disease as an attack confers lifelong immunity.
The natural host of the LCM virus is the common house mouse, Mus musculus. Humans acquire the infection by contact with infected hamsters or with dust contaminated by mouse excreta. Laboratory workers who handle rodents may be exposed to LCM. The meningitis may be preceded by respiratory symptoms, sometimes with pulmonary infiltrates. The infection is particularly common in late fall and winter, presumably because mice enter dwellings at that time.
Parvovirus causes fifth disease in young children, characterized by high fever and markedly flushed cheeks but not associated with neurologic symptoms beyond irritability and sometimes, febrile seizures. However, when contracted from the child by an adult, various neurologic manifestations such as brachial neuritis can occur. There have been reports of encephalitis and meningitis with the B-19 strain, particularly in children and sometimes in individuals with altered immunity. By a difficult to understand complication, some patients have had strokes with parvoviral infection as discussed in the review by Douvoyiannis and colleagues.
HSV-2 and HIV may be associated with a cauda equina neuritis and meningitis. In the case of HSV, there is often a preceding genital infection with the virus (see Chap. 42). The presence of sore throat, generalized lymphadenopathy, transient rash, and mild icterus is suggestive of infectious mononucleosis caused by EBV or, at times, CMV infection. Icterus is a prominent manifestation of viral hepatitis and some serotypes of leptospirosis and, at times, of Q fever. Among the bacterial and spirochetal cause of an aseptic meningitis syndrome, leptospirosis, M. pneumoniae, and Lyme borreliosis are notable as discussed in the previous chapter.
Certain forms of encephalitis occur particularly in individuals who are immunosuppressed from HIV, chemotherapy for neoplasm, organ transplantation, or hematologic and lymphoid malignancy. The manifestation is usually encephalitis but aseptic meningitis is known to occur. The main causative organisms in this group are HHV-6, CMV, and VZV.