Usefulness of diverse serological tests in the laboratory diagnosis of fever with skin-rash cases in children

Abstract

Objective: The Government of India (GoI) is working towards measles and rubella (MR) elimination in a phased manner. Serological and molecular confirmation of cases in research laboratories is crucial for measles and rubella (MR) elimination goal-2023. Methods: A study was designed to understand the qualitative and quantitative correlation of IgM, IgG, IgG-avidity and Nt-antibodies to Measles virus (MeV) and Rubella virus (RuV) in fever with skin-rash cases aged between 1–15 years. For this purpose, sera collected and referred during 2014–16 were used. Results: A total of 42%, 86.0% and 97.3% cases show MeV-specific IgM, IgG and Nt antibodies, respectively and 22.7%, 59.3% and 72.3% show RuV-specific IgM, IgG and Nt antibodies, respectively. Amongst laboratory-confirmed cases, 69.0% (low) and 26.2% (high) have IgG antibody-avidity for measles, whereas 62.5% (low) and 31.3% (high) have IgG antibody avidity for rubella. In the ‘non-measles and non-rubella’ cases, 11.9% show low and 84.3% cases have high avidity for measles, whereas low avidity for rubella was detected in 12.7% and high avidity in 84.6% cases, indicating acute or past/reinfection. Overall, MeV-specific Nt and RuV-specific IgG antibody-avidity positivity was highest compared to IgM. Conclusions: Large percentage of cases have Nt antibodies to MeV and IgG antibody-avidity to RuV compared to IgM antibodies. Acute infection confirmed by low IgG avidity was 37.2% and 23.9% for measles and rubella, respectively. Measles and Rubella past/reinfection was observed in 58.6% and 72.6% cases, respectively. Thus the present study indicates usefulness of various serological tests for case confirmation.

Keywords

• Fever-skin-rashes
• Serological diagnosis
• Measles virus
• Rubella virus
• IgM antibody
• IgG antibody