Volume 30, Number 5—May 2024
Research
Analysis of Suspected Measles Cases with Discrepant Measles-Specific IgM and rRT-PCR Test Results, Japan
, Minoru Nidaira, Noriyuki Maeshiro, Katsuhiro Komase, Hajime Kamiya, and Hisako Kyan
Table 2
Characteristics and laboratory results for 24 suspected measles cases with discrepant measles-specific IgM and rRT-PCR test results, Japan*
| Case no. |
Age/ sex |
No. measles vaccine doses |
Fever, °C |
Rash |
Time to specimen collection, d |
IgM/ IgG† |
% RAI, avidity‡ |
Other febrile exanthematous viruses detected on PCR |
Results§ |
Measles virus infection |
|||
| After vaccine |
After fever onset |
Throat swab |
Serum |
Urine |
|||||||||
| 1 |
6 mo/M |
1 |
39.5 |
Y |
4 |
3 |
1.37/ND |
ND, L |
HHV-6 |
HHV-6 |
ND |
CX
or MCV |
N |
| 2 |
1 y/F |
1 |
40.0 |
Y |
6 |
0 |
1.56/ND |
ND, L |
CMV |
ND |
ND |
CX
or MCV |
N |
| 3 |
1 y/M |
1 |
40.0 |
Y |
18 |
2 |
4.71/ 984.9 |
16.6, L |
HHV-6 |
HHV-6 |
ND |
MCV |
N |
| 4 |
4 y/F |
1 |
+ |
N |
26 |
1 |
1.78/ 2,286 |
35.9, L |
EBV, HHV-6, CMV |
ND |
CMV |
MCV |
N |
| 5 |
10 mo/M |
1 |
37.9 |
Y |
11 |
1 |
1.74/ 149.2 |
39.6, L |
CMV |
ND |
CMV |
CX
or MCV |
N |
| 6 |
9 mo/M |
1 |
38.0 |
Y |
16 |
0 |
3.96/ 1,200 |
21.7, L |
HHV-6, CMV |
ND |
ND |
MCV |
N |
| 7 |
11 mo/F |
1 |
Y |
Y |
21 |
1 |
6.83/ 1,242 |
24.6, L |
CMV |
ND |
CMV |
MCV |
N |
| 8 |
6 mo/M |
1 |
38.7 |
Y |
16 |
0 |
5.54/ 1,224 |
15.6, L |
CMV |
HHV-6, CMV |
HPeV, CMV |
MCV |
N |
| 9 |
7 mo/F |
1 |
39.0 |
Y |
12 |
2 |
2.74/ 14.4 |
17.3, L |
ND |
ND |
ND |
MCV |
N |
| 10 |
9 mo/M |
1 |
38.3 |
Y |
24 |
0 |
2.53/ 1,037 |
14.0, L |
ND |
ND |
ND |
MCV |
N |
| 11 |
7 mo/M |
1 |
38.2 |
Y |
42 |
0 |
2.50/ 2,112 |
17.5, L |
ND |
HPeV |
ND |
MCV |
N |
| 12 |
11 mo/M |
1 |
39.1 |
Y |
58 |
1 |
2.39/ 1,033 |
18.4, L |
ND |
ND |
ND |
MCV |
N |
| 13 |
1 y/F |
1 |
39.3 |
Y |
47 |
6 |
1.23/ 1,606 |
27.9, L |
ND |
CMV |
CMV |
MCV |
N |
| 14 |
7 mo/F |
1 |
38.0 |
Y |
25 |
4 |
2.15/ 396.7 |
12.3, L |
ND |
ND |
ND |
MCV |
N |
| 15 |
6 mo/F |
1 |
38.9 |
Y |
18 |
10 |
4.56/ 1,118 |
17.8, L |
ND |
ND |
ND |
MCV |
N |
| 16 |
1 y/M |
1 |
Y |
Y |
33 |
5 |
1.42/ 1,047 |
28.1, L |
HHV-6, HPeV |
HHV-6 |
ND |
MCV |
N |
| 17 |
10 mo/F |
1 |
39.4 |
Y |
41 |
4 |
1.37/ 4,440 |
25.5, L |
HHV-6 |
HHV-6 |
HHV-6 |
MCV |
N |
| 18 |
1 y/M |
1 |
40.4 |
Y |
61 |
6 |
3.82/ 1,825 |
47.9, E |
ND |
ND |
ND |
MCV |
N |
| 19 |
1 y/F |
1 |
39.0 |
Y |
88 |
3 |
1.45/ >5,000 |
50.6, E |
ND |
ND |
ND |
MCV |
N |
| 20 |
1 y/F |
1 |
40.6 |
Y |
136 |
10 |
2.25/ 2,076 |
76.1, H |
ND |
HHV-6 |
ND |
MCV or CX |
N |
| 21 |
24 y/F |
Unk |
38.8 |
Y |
Unk |
2 |
2.55/ >5,000 |
79.7, H |
HHV-7 |
ND |
ND |
RI or
CX |
Y or N |
| 22 |
21 y/M |
2 |
38.0 |
Y |
Unk |
5 |
2.05/ >5,000 |
88.4, H |
ND |
ND |
ND |
RI |
Y |
| 23 |
29 y/M |
Unk |
Y |
Y |
Unk |
5 |
3.89/ 4,228 |
91.7, H |
ND |
ND |
ND |
RI |
Y |
| 24 | 45 y/M | Unk | 39.1 | Y | Unk | 5 | 1.29/ 518.7 | 91.0, H | HHV-7, B19 | B19 | ND | RI or CX | Y or N |
*B19, human parvovirus B19; CMV, cytomegalovirus; CX, cross-reaction; E, equivocal; EBV, Epstein-Barr virus; H, high; HHV-6, human herpesvirus 6; HHV-7, human herpesvirus 7; HPeV, human parechovirus; L, low; MCV, measles-containing vaccine; ND, not detected; RAI, relative avidity index; RI, reinfection; Unk, unknown. †IgM values indicate RU; IgG values indicate IU/L. ‡IgG avidity test results can help distinguish recent primary infection (characterized by a low RAI) from past infection (characterized by a high RAI). RAI <40% indicated low-avidity antibodies, RAI 40%–60% equivocal, and RAI >60% indicated high-avidity antibodies. §MCV indicates that an increased IgM titer might be influenced by vaccination with a measles-containing vaccine; CX indicates a cross-reaction of a febrile exanthematous virus infection other than the measles virus, respectively.
1Current affiliation: Center for Emergency Preparedness and Response, National Institute of Infectious Diseases, Tokyo, Japan.