Key points
NESS is a voluntary, passive surveillance system that collects basic data on specimens positive for enterovirus or human parechovirus. Public health practitioners, researchers, and clinicians use NESS data to determine circulation patterns of individual enterovirus and parechovirus types. However, NESS data are not necessarily representative of all enterovirus or parechovirus infections in the United States.
Summary of 2023 Ness Data
- NESS received data for 198 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result in 2023.
- In addition to the CDC laboratory, labs from 6 states reported to NESS in 2023.
- Coxsackievirus B4 was the most frequently reported enterovirus type (16.7%).
- The second most frequently reported virus type in 2023 was Coxsackievirus A6 (13.1%).
- Among those with a known specimen source, the most common specimen sources were cerebrospinal fluid (48%), throat/nasopharyngeal (NP) swab (27.3%), and stool/rectal swab (14.1%).
Most Common Enteroviruses and Parechoviruses Reported in the U.S., 2023*
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Coxsackievirus B4 | 16.7% | 33 |
| Coxsackievirus A6 | 13.1% | 26 |
| Coxsackievirus B5 | 12.6% | 25 |
| Echovirus 18 | 11.6% | 23 |
| Coxsackievirus A9 | 6.1% | 12 |
| Echovirus 5 | 4.5% | 9 |
| Coxsackievirus A10 | 4% | 8 |
| Coxsackievirus B1 | 4% | 8 |
| Coxsackievirus A16 | 3% | 6 |
| Coxsackievirus B3 | 3% | 6 |
| Enterovirus A71 | 3% | 6 |
| Coxsackievirus A5 | 2.5% | 5 |
| Coxsackievirus A2 | 1.5% | 3 |
| Coxsackievirus B2 | 1.5% | 3 |
| Echovirus 11 | 1.5% | 3 |
| Echovirus 25 | 1.5% | 3 |
| Echovirus 30 | 1.5% | 3 |
| Echovirus 6 | 1.5% | 3 |
| Coxsackievirus A21 | 1% | 2 |
| Echovirus 3 | 1% | 2 |
| Echovirus 7 | 1% | 2 |
| Echovirus 9 | 1% | 2 |
| Parechovirus A3 | 1% | 2 |
| Coxsackievirus A4 | 0.5% | 1 |
| Parechovirus A4 | 0.5% | 1 |
| Parechovirus A6 | 0.5% | 1 |
NOTE: Multiple specimens from the same patient can be reported to NESS, so the number of specimens does not necessarily correspond to the number of patients affected. Data are preliminary as of April 2024.
* NESS is a voluntary, passive surveillance system and is limited to laboratories that perform serotyping for enteroviruses and/or parechoviruses. Non-polio enterovirus and parechovirus infections are not mandated reportable conditions in the United States, so not all detections are reported to NESS. In addition, most laboratories do not have the capacity to perform serotyping on enterovirus and parechovirus specimens, and serotyping is not routinely performed as part of clinical care. Therefore, NESS data are not necessarily representative of all enterovirus or parechovirus infections in the United States and should be interpreted with caution.
Read more about how public health professionals collect and use NESS data.
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About NESS
Summary of 2022 NESS Data
- NESS received data for 360 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result.
- In addition to the CDC laboratory, labs from 4 states reported to NESS in 2022.
- Enterovirus D68 (EV-D68) was the most frequently reported enterovirus type (40.0%). There was a large, nationwide outbreak of respiratory illness associated with EV-D68 in 2022 and there is also a specific test for EV-D68, which might mean that this virus is more likely to be detected and reported, as compared to other enteroviruses. These factors might contribute to the number of EV-D68 detections reported to NESS.
- The second most frequently reported virus type in 2022 was human parechovirus A3 (20.3%). In July 2022, in response to reports of neonatal and infant parechovirus infections from clinicians in multiple states, a Health Alert Network (HAN) health advisory was released, and the CDC lab offered parechovirus testing and typing for infants with severe disease or suspected parechovirus infection. This might contribute to the number of parechovirus detections reported to NESS.
- It is also noteworthy that two poliovirus specimens were reported to NESS in 2022. These specimens were from the paralytic polio case patient identified in New York State and were determined to be vaccine-derived poliovirus type 2 (VDPV2) that was genetically linked to virus found in wastewater in the United Kingdom, Israel, and Canada.
- Among those with a known specimen source, the most common specimen sources were throat/nasopharyngeal (NP) swab (58.1%), cerebrospinal fluid (28.3%), and stool/rectal swab (8.9%).
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Enterovirus D68 | 40% | 144 |
| Parechovirus A3 | 20.3% | 73 |
| Coxsackievirus A6 | 6.1% | 22 |
| Coxsackievirus A9 | 5% | 18 |
| Coxsackievirus B5 | 4.7% | 17 |
| Coxsackievirus B3 | 4.4% | 16 |
| Echovirus 11 | 2.8% | 10 |
| Enterovirus A71 | 2.2% | 8 |
| Coxsackievirus B2 | 1.7% | 6 |
| Coxsackievirus A16 | 1.4% | 5 |
| Coxsackievirus A4 | 1.4% | 5 |
| Coxsackievirus B4 | 1.4% | 5 |
| Echovirus 6 | 1.4% | 5 |
| Echovirus 9 | 1.4% | 5 |
| Echovirus 25 | 0.8% | 3 |
| Coxsackievirus A10 | 0.6% | 2 |
| Echovirus 14 | 0.6% | 2 |
| Echovirus 30 | 0.6% | 2 |
| Echovirus 5 | 0.6% | 2 |
| Parechovirus A4 | 0.6% | 2 |
| Parechovirus A6 | 0.6% | 2 |
| Poliovirus 2 | 0.6% | 2 |
| Coxsackievirus A15 | 0.3% | 1 |
| Coxsackievirus A2 | 0.3% | 1 |
| Coxsackievirus A5 | 0.3% | 1 |
| Coxsackievirus B1 | 0.3% | 1 |
NOTE: Multiple specimens from the same patient can be reported to NESS, so the number of specimens does not necessarily correspond to the number of patients affected. Data were revised and finalized on May 29, 2024.
* NESS is a voluntary, passive surveillance system and is limited to laboratories that perform serotyping for enteroviruses and/or parechoviruses. Non-polio enterovirus and parechovirus infections are not mandated reportable conditions in the United States, so not all detections are reported to NESS. In addition, most laboratories do not have the capacity to perform serotyping on enterovirus and parechovirus specimens, and serotyping is not routinely performed as part of clinical care. Therefore, NESS data are not necessarily representative of all enterovirus or parechovirus infections in the United States and should be interpreted with caution.
2021 Data Summary
- NESS received data on 47 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result.
- In addition to the CDC laboratory, labs from 4 states reported to NESS in 2021.
- The most frequently reported virus in 2021 was coxsackievirus A6 (34.0%). It is notable that the number of reports to NESS was significantly lower in 2020 and 2021, as compared with other years. Therefore, the results for 2021 should be interpreted with caution.
- Among those with known specimen source, the most common specimen sources were throat/NP swab (57.8%), stool/rectal swab (24.4%), and cerebrospinal fluid (13.3%).
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Coxsackievirus A6 | 34.0% | 16 |
| Echovirus 11 | 12.8% | 6 |
| Enterovirus A71 | 12.8% | 6 |
| Coxsackievirus A5 | 6.4% | 3 |
| Coxsackievirus B2 | 6.4% | 3 |
| Human Parechovirus 1 | 6.4% | 3 |
| Coxsackievirus A2 | 4.3% | 2 |
| Enterovirus D68 | 4.3% | 2 |
| Coxsackievirus A8 | 2.1% | 1 |
| Coxsackievirus A9 | 2.1% | 1 |
| Coxsackievirus B3 | 2.1% | 1 |
| Coxsackievirus B5 | 2.1% | 1 |
| Echovirus 25 | 2.1% | 1 |
| Echovirus 9 | 2.1% | 1 |
2020 Data Summary
- NESS received data on 43 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result.
- In addition to the CDC laboratory, labs from 2 states reported to NESS in 2020.
- In 2020, the majority of reports (53.5%) were for enterovirus D68 (EV-D68). There is a specific test for EV-D68, which might mean that this virus is more likely to be detected than other enteroviruses. This might contribute to the number of EV-D68 detections reported to NESS.
- It is also notable that the number of reports to NESS was significantly lower in 2020 and 2021 compared to other years. Therefore, the results for 2020 should be interpreted with particular caution.
- Among those with known specimen source, the most common specimen sources were throat/NP swab (72.1%), cerebrospinal fluid (9.3%), and serum (7.0%).
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Enterovirus D68 | 53.5% | 23 |
| Coxsackievirus A10 | 9.3% | 4 |
| Coxsackievirus A21 | 9.3% | 4 |
| Coxsackievirus A6 | 7.0% | 3 |
| Enterovirus A71 | 4.7% | 2 |
| Enterovirus C105 | 4.7% | 2 |
| Coxsackievirus B3 | 2.3% | 1 |
| Echovirus 18 | 2.3% | 1 |
| Echovirus 25 | 2.3% | 1 |
| Echovirus 9 | 2.3% | 1 |
| Enterovirus C109 | 2.3% | 1 |
2019 Data Summary
- NESS received data on 192 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result.
- In addition to the CDC laboratory, labs from 6 states reported to NESS in 2019.
- The most frequently reported viruses in 2019 were coxsackievirus A6 (15.6%), coxsackievirus B4 (13.5%), echovirus 11 (7.3%), and echovirus 5 (7.3%).
- Among those with known specimen source, the most common specimen sources were throat/NP swab (40.3%), cerebrospinal fluid (37.8%), and stool/rectal swab (14.1%).
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Coxsackievirus A6 | 15.6% | 30 |
| Coxsackievirus B4 | 13.5% | 26 |
| Echovirus 11 | 7.3% | 14 |
| Echovirus 5 | 7.3% | 14 |
| Coxsackievirus A9 | 6.2% | 12 |
| Enterovirus D68 | 5.2% | 10 |
| Coxsackievirus B3 | 4.7% | 9 |
| Echovirus 18 | 4.2% | 8 |
| Echovirus 25 | 4.2% | 8 |
| Echovirus 30 | 4.2% | 8 |
| Enterovirus A71 | 4.2% | 8 |
| Echovirus 9 | 3.6% | 7 |
| Coxsackievirus A21 | 2.6% | 5 |
| Coxsackievirus A4 | 2.1% | 4 |
| Coxsackievirus B2 | 1.6% | 3 |
| Coxsackievirus B5 | 1.6% | 3 |
| Echovirus 3 | 1.6% | 3 |
| Echovirus 6 | 1.6% | 3 |
| Enterovirus C105 | 1.6% | 3 |
| Coxsackievirus A16 | 1.0% | 2 |
| Coxsackievirus A8 | 1.0% | 2 |
| Echovirus 7 | 1.0% | 2 |
| Enterovirus C109 | 1.0% | 2 |
| Human Parechovirus 3 | 1.0% | 2 |
| Coxsackievirus A10 | 0.5% | 1 |
| Coxsackievirus A2 | 0.5% | 1 |
| Echovirus 13 | 0.5% | 1 |
| Echovirus 21 | 0.5% | 1 |
2018 Data Summary
- NESS received data on 552 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result.
- In addition to the CDC laboratory, labs from 5 states reported to NESS in 2018.
- Enterovirus D68 (EV-D68) was the most frequently reported virus in 2018 (28.1%), and enterovirus A71 (EV-A71) was the second most frequently reported. In 2018, there was a large increase in cases of acute flaccid myelitis (AFM), which has been associated with both EV-D68 and EV-A71, in 2018. There is also a specific test for EV-D68 which might mean that this virus is more likely to be detected than other enteroviruses. This might contribute to the number of EV-D68 detections reported to NESS.
- Among those with known specimen source, the most common specimen sources were throat/NP swab (51.94, cerebrospinal fluid (24.3%), and stool/rectal swab (18.9%).
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Enterovirus D68 | 28.1% | 155 |
| Enterovirus A71 | 16.8% | 93 |
| Coxsackievirus B5 | 11.4% | 63 |
| Coxsackievirus A6 | 11.1% | 61 |
| Echovirus 30 | 6.5% | 36 |
| Echovirus 11 | 5.1% | 28 |
| Coxsackievirus A9 | 2.2% | 12 |
| Echovirus 18 | 2.0% | 11 |
| Coxsackievirus B3 | 1.8% | 10 |
| Coxsackievirus A10 | 1.4% | 8 |
| Coxsackievirus A2 | 1.4% | 8 |
| Coxsackievirus A16 | 1.3% | 7 |
| Coxsackievirus B2 | 1.3% | 7 |
| Echovirus 6 | 1.3% | 7 |
| Echovirus 9 | 1.3% | 7 |
| Human Parechovirus 3 | 1.3% | 7 |
| Coxsackievirus A5 | 1.1% | 6 |
| Coxsackievirus B4 | 1.1% | 6 |
| Echovirus 25 | 0.9% | 5 |
| Coxsackievirus A8 | 0.5% | 3 |
| Echovirus 5 | 0.5% | 3 |
| Coxsackievirus A4 | 0.4% | 2 |
| Coxsackievirus B1 | 0.4% | 2 |
| Echovirus 3 | 0.4% | 2 |
| Echovirus 13 | 0.2% | 1 |
| Echovirus 7 | 0.2% | 1 |
| Human Parechovirus 6 | 0.2% | 1 |
2017 Data Summary
- NESS received data on 353 specimens that tested positive for either an enterovirus or parechovirus and had a serotype result.
- In addition to the CDC laboratory, labs from 6 states reported to NESS in 2017.
- The most frequently reported viruses in 2017 were echovirus 30 (19.8%), coxsackievirus B5 (14.7%), and echovirus 9 (13.3%).
- Among those with known specimen source, the most common specimen sources were cerebrospinal fluid (50.1%), throat/NP swab (38.0%), and stool/rectal swab (5.8%).
| Enterovirus or parechovirus type | Proportion of positive specimens | Number of positive specimens |
|---|---|---|
| Echovirus 30 | 19.8% | 70 |
| Coxsackievirus B5 | 14.7% | 52 |
| Echovirus 9 | 13.3% | 47 |
| Echovirus 6 | 7.1% | 25 |
| Coxsackievirus B1 | 5.4% | 19 |
| Enterovirus D68 | 4.8% | 17 |
| Coxsackievirus A16 | 4.2% | 15 |
| Coxsackievirus A6 | 4.2% | 15 |
| Coxsackievirus B2 | 4.2% | 15 |
| Echovirus 11 | 4.0% | 14 |
| Enterovirus A71 | 3.4% | 12 |
| Coxsackievirus A9 | 1.7% | 6 |
| Coxsackievirus B4 | 1.7% | 6 |
| Coxsackievirus A4 | 1.4% | 5 |
| Echovirus 25 | 1.4% | 5 |
| Coxsackievirus B3 | 1.1% | 4 |
| Echovirus 33 | 1.1% | 4 |
| Coxsackievirus A10 | 0.8% | 3 |
| Coxsackievirus A2 | 0.8% | 3 |
| Echovirus 7 | 0.8% | 3 |
| Human Parechovirus 3 | 0.8% | 3 |
| Echovirus 5 | 0.6% | 2 |
| Enterovirus B84 | 0.6% | 2 |
| Human Parechovirus 1 | 0.6% | 2 |
| Coxsackievirus A21 | 0.3% | 1 |
| Coxsackievirus A5 | 0.3% | 1 |
| Echovirus 16 | 0.3% | 1 |
| Echovirus 3 | 0.3% | 1 |
- CDC. Enterovirus and parechovirus surveillance, United States, 2014 — 2016. MMWR. 2018; 67(18);515–8.
- CDC. Enterovirus and human parechovirus surveillance – United States, 2009-2013. MMWR. 2015;64(34):940-3.