Distribution of Anti-Mumps IgM Antibody in Children Presumptively Diagnosed of Mumps

ABSTRACT

PURPOSE: Outbreaks of mumps continue to occur, even though the number of patients diagnosed of mumps has decreased considerably with the widespread use of vaccine. The accurate diagnosis of mumps is needed to understand the epidemiology of mumps and analyse the safety and effectiveness of vaccine. Therefore, we attempted to appraise the accuracy of provisional diagnosis of mumps in clinical practice by measuring mumps specific antibody. METHODS: Thirty-six patients with presumptive diagnosis of mumps were enrolled from four university hospitals. Medical history including MMR vaccination was obtained, and anti-mumps IgM antibody test(ELISA. Denka Seiken Co., Ltd., Tokyo, Japan), complete blood counts and amylase were measured. RESULTS: Among 36 patients presumptively diagnosed of mumps, anti-mumps IgM antibody was positive in 14 patients(38.8%), negative in 20(55.5%) and equivocal in 2(5.5%). In two patients who were not vaccinated against mumps, one had anti-mumps IgM antibody and the other did not. All four patients, vaccinated with MMR twice after their first birthday did not have anti-mumps IgM antibody. The sites of involved glands and the associated localized as well as systemic symptomatologies were not different between patients with anti-mumps antibody and those without. The proportion and degree of increment of serum amylase level were not different between the two groups. CONCLUSION: A significant number of patients with provisional diagnosis of mumps appear to be due to other causes. Amylase, commonly used in clinical practice, does not differentiate mumps from other illnesses involving the parotid glands. Mumps can be accurately diagnosed only by laboratory tests including anti-mumps antibody. The two-dose MMR vaccination program needs to be reinforced.