When a Common Virus Turns Dangerous for Newborns: What Families Should Know About Echovirus 11

What four 2025 reports from Japan, Italy, China and Taiwan (Ikuse, Perniciaro, Xuan and Wang and their colleagues) tell us about how a newer strain spread, how babies catch it, how doctors care for them and what happens afterwards

Echovirus 11 is a common virus that usually causes only mild illness, but in rare cases it can make a baby in the first weeks of life seriously ill. Four reports published in 2025, from Japan, Italy, China and Taiwan, explain how a newer strain has spread, how newborns catch it, what hospital care can offer and why survivors need follow-up.

Most parents will never hear of echovirus 11, and most babies who catch it have only a mild illness. Knowing a little about it can still help, because the rare serious cases move quickly and early medical attention matters. This article explains, in plain language, what doctors have learned recently and what it means for families.

Four reports that tell one connected story

Echovirus 11, often shortened to E11, belongs to a large family of common summer viruses called enteroviruses, which usually cause colds, tummy upsets and rashes. In 2025, four teams of doctors published reports that fit together like chapters of one story. In Tokyo, Japan, doctors described three baby boys, born at full term, who became ill at about a week old with yellow skin, poor feeding and sleepiness, developed liver failure and sadly died; their virus belonged to the same newer strain that had caused severe cases in Europe [1]. In Varese, Italy, doctors described twin boys born a few weeks early who both caught E11, probably from their mother around birth; one became gravely ill and died at 10 days old, while his brother stayed completely well [2]. In Zhuzhou, China, a hospital looked back at 193 newborns treated for enterovirus infections over four years and compared the 44 who became seriously ill with the 149 who had milder illness [3]. That study did not test which enterovirus each baby had, so its lessons apply to serious newborn enterovirus infections in general, not to E11 alone. In Taipei, Taiwan, doctors described a baby girl, born a few weeks early to a mother who had a fever during labour, who became very sick at 3 days old and died at 6 days, and they reviewed what is known about how babies catch the virus [4]. Together, the reports trace a path from a virus spreading around the world, to how babies catch it, to what care can and cannot do, to life afterwards.

A virus doctors have known about for decades

E11 is not new. As long ago as 1986, a review of 61 serious echovirus infections in newborns found that about 7 in 10 were caused by E11, that illness usually started between the third and fifth day of life, and that in about two-thirds of cases the mother had been ill in the week before delivery [5]. Babies whose liver was badly affected were the most likely to die, whereas babies infected later, for example from other babies in a hospital nursery, usually had milder illness. A 2021 review of 237 serious newborn enterovirus cases from around the world found that 7 in 10 began in the first week of life [6]. Hospitals also learned how to stop the virus spreading between babies: when E11 reached the neonatal intensive care units (NICUs, the hospital wards for sick newborns) of a Taiwanese hospital in 2018, isolation, rapid testing and extra cleaning brought the outbreak under control, and all 10 affected babies recovered [7]. For many years, then, serious E11 illness was a rare but recognised danger that doctors knew how to watch for. That changed in 2022, when doctors in France noticed an unusual cluster: nine newborn boys, eight of them twins, became seriously ill between July 2022 and April 2023, and seven died [8]. By July 2023, European health authorities had counted 19 severe newborn cases across several countries [2].

How a newer strain travelled around the world

Viruses change over time, and scientists read their genetic code to follow them, much as one might trace a family tree. The Tokyo team found that their three babies' viruses belonged to a branch called "new lineage 1", the same branch seen in the European cases, and estimated that it first appeared around 2016, before the COVID-19 pandemic [1]. In Japan, reports of E11 rose sharply in 2024, mostly between August and November, and national health bodies alerted doctors in December 2024. Newer studies, so far available to us only as short summaries, suggest that E11 has also become the most common enterovirus among newborns admitted to one large hospital in Taiwan [9] and has caused serious illness in newborns in Malaysia [10]. It is important to keep this in proportion. In Spain, where the same strain arrived, most newborns with it did not need intensive care [1], and researchers found no rise in how often newborns with E11 needed intensive care after the new strain appeared [11]. Scientists are still working out whether this strain is truly more dangerous or simply more widespread.

How newborns catch the virus

The Taiwanese team explained that the timing of infection matters most [4]. When a mother catches the virus in the last one to two weeks of pregnancy, she has not had time to make protective antibodies (the body's infection-fighting proteins) and pass them to her baby through the placenta, so the baby meets the virus unprotected. These babies usually become ill between days 3 and 7 and have the most serious illness. Babies who catch the virus later, after birth, usually already carry some of their mother's antibodies and tend to have milder illness. The Taiwanese mother had a fever during labour, and her older daughter had recently had an enterovirus illness. In the Italian twins, the virus was found in a swab from the mother's birth canal, which suggests that the babies caught it around birth, even though she had only had a mild runny nose [2]. A review of earlier research found that most seriously ill newborns had caught the virus around the time of birth [12]. The virus can also spread after birth, from family members or between babies: one Tokyo baby's father had had a fever, although how that baby caught the virus is not known [1], and in Malaysia, three of five sick babies had come from postnatal care centres [10]. Being born early, being a boy and being a twin also appear to raise the risk, although the reasons are not yet understood [2].

Warning signs doctors look for

Babies who became seriously ill usually did so in the first week of life. In the Chinese study, which, as noted, did not identify the exact virus, about three in four seriously ill babies became unwell in their first seven days, compared with about one in seven of those with milder illness [3]. Seriously ill babies were less likely than mildly ill ones to have a fever, and more likely to have a rash, breathing problems, or to feed, cry and move less than usual. Blood tests told an important story: more than eight in ten seriously ill babies had very low platelets (the blood cells that help clotting) and slow blood clotting, and about two in three had signs of liver damage. The Italian twin showed how fast things can change, with his platelets falling to a dangerous level on day 7 and severe liver damage by the next day [2]. Some babies developed an overactive immune reaction that harms the body's own organs [1], and in the Taiwanese baby the heart muscle became inflamed [4]. For parents, the practical message is that a newborn who is feeding poorly, unusually sleepy, yellow, breathing with difficulty or has a fever, especially in the first weeks of life, deserves prompt medical attention, whatever the cause.

What treatment can and cannot do

There is still no routinely available medicine that directly stops echoviruses, so care focuses on supporting the baby's organs while the body fights the infection. This can include a breathing machine, transfusions of blood and platelets, medicines to support blood pressure, kidney dialysis and, in a few cases, a heart–lung bypass machine called ECMO (extracorporeal membrane oxygenation) [3]. Many babies also receive immunoglobulin, a medicine made from donated antibodies, and one study suggested it may help most when given within three days of illness starting [13], although experts still debate how well it works [4]. Even with all this care, 24 of the 44 seriously ill babies in the Chinese hospital died, although, as noted, that study did not identify which virus each baby had [3]. An experimental antiviral medicine called pleconaril was tested in 61 newborns at several hospitals in the United States, in a carefully designed study run by a national research group in which babies were assigned by chance to receive the medicine or a dummy treatment; fewer babies died among those who received the medicine, but it cannot be bought [14]. Another experimental drug can only be obtained through special emergency programmes [2]. For two of the Japanese babies, doctors considered a liver transplant, but neither baby was well enough to receive one [1].

Life after a serious infection

Most babies with milder illness do well: all 149 babies with milder illness in the Chinese study survived [3]. For babies who survive serious illness, recovery can take time. In the same study (again, without knowing the exact virus), the results table records 7 of the 20 seriously ill survivors needing rehabilitation for movement or learning difficulties during about a year of follow-up, although the written text of the report gives a higher figure, so the true proportion is uncertain. A Japanese report, so far available to us only as a summary, describes a baby boy who survived liver failure caused by the newer E11 strain but was left with a slow-to-heal liver problem in which bile did not drain properly [15]. He needed medicines and vitamins until about his first birthday, after which all were stopped, and his doctors recommend regular liver and nutrition check-ups for such babies after they go home. The Italian twin who stayed well was growing normally at follow-up [2].

What families can do, and what researchers are working on next

For families, the most useful steps are simple. If a mother develops a fever, tummy upset or other illness close to delivery, or if a sibling or partner is unwell, telling the midwife or doctor helps them decide how closely to watch the baby [4]. Hospitals can test for the virus quickly and keep infected babies apart from others, steps that helped end an earlier outbreak [7]. Researchers are tracking how the virus changes as it moves between countries, and are asking whether mothers carry fewer protective antibodies against the newer strain [1]. Others want to find out whether giving immunoglobulin earlier helps [13] and following survivors to understand their long-term health [3]. Serious E11 illness remains uncommon, but these four reports show that awareness, early care and careful follow-up give babies the best possible chance.

References

  1. Ikuse T, Matsui T, Shoji K, et al. Neonatal acute liver failure cases with echovirus 11 infections, Japan, August to November 2024. Euro Surveill. 2025;30(1):2400822. doi:10.2807/1560-7917.ES.2025.30.1.2400822 ↩
  2. Perniciaro S, Proietti C, Bossi A, et al. Two dramatically different clinical scenarios of neonatal Echovirus-11 infection in late preterm male twins: a case report and review of the literature. Ital J Pediatr. 2025;51(1):49. doi:10.1186/s13052-025-01880-5 ↩
  3. Xuan Z, Wang T, Li N, et al. Analysis of clinical characteristics and the effect of symptomatic supportive treatment for severe neonatal enterovirus infection. Infect Drug Resist. 2025;18:2629-2636. doi:10.2147/IDR.S507842 ↩
  4. Wang MJ, Lee CC, Chang HY, et al. Fatal neonatal echovirus 11 infection following maternal peripartum illness: a case report with literature review. AJP Rep. 2025;15(4):e181-e185. doi:10.1055/a-2764-2405 ↩
  5. Modlin JF. Perinatal echovirus infection: insights from a literature review of 61 cases of serious infection and 16 outbreaks in nurseries. Rev Infect Dis. 1986;8(6):918-926. doi:10.1093/clinids/8.6.918 ↩
  6. Zhang M, Wang H, Tang J, et al. Clinical characteristics of severe neonatal enterovirus infection: a systematic review. BMC Pediatr. 2021;21(1):127. doi:10.1186/s12887-021-02599-y ↩
  7. Ho SY, Chiu CH, Huang YC, et al. Investigation and successful control of an echovirus 11 outbreak in neonatal intensive care units. Pediatr Neonatol. 2020;61(2):180-187. doi:10.1016/j.pedneo.2019.09.012 ↩
  8. Grapin M, Mirand A, Pinquier D, et al. Severe and fatal neonatal infections linked to a new variant of echovirus 11, France, July 2022 to April 2023. Euro Surveill. 2023;28(22):2300253. doi:10.2807/1560-7917.ES.2023.28.22.2300253 ↩
  9. Ho SY, Liu YC, Ho SY, et al. Emergence of echovirus 11 in severe and neonatal enterovirus infections: a 9-year retrospective study in Taiwan before and after the COVID-19 pandemic. J Med Virol. 2026;98(4):e70929. doi:10.1002/jmv.70929 ↩
  10. Chuah SL, Lau JZH, Gan CS, et al. Postnatal care-associated echovirus 11 infection in Malaysia: severe disease with variable outcomes. Pediatr Infect Dis J. 2026 (published online 27 May 2026; volume and pages not yet assigned). doi:10.1097/INF.0000000000005303 ↩
  11. Fernandez-Garcia MD, Garcia-Ibañez N, Camacho J, et al. Enhanced echovirus 11 genomic surveillance in neonatal infections in Spain following a European alert reveals new recombinant forms linked to severe cases, 2019 to 2023. Euro Surveill. 2024;29(44):2400221. doi:10.2807/1560-7917.ES.2024.29.44.2400221 ↩
  12. Kang CR, Byeon JH, Cho H, et al. Perinatal enterovirus infection in neonates: a systematic review. J Med Virol. 2025;97(5):e70362. doi:10.1002/jmv.70362 ↩
  13. Yen MH, Huang YC, Chen MC, et al. Effect of intravenous immunoglobulin for neonates with severe enteroviral infections with emphasis on the timing of administration. J Clin Virol. 2015;64:92-96. doi:10.1016/j.jcv.2015.01.013 ↩
  14. Abzug MJ, Michaels MG, Wald E, et al. A randomized, double-blind, placebo-controlled trial of pleconaril for the treatment of neonates with enterovirus sepsis. J Pediatric Infect Dis Soc. 2016;5(1):53-62. doi:10.1093/jpids/piv015 ↩
  15. Ogawa E, Mizutani H, Okumura T, et al. Prolonged cholestasis following severe neonatal echovirus 11 (genotype D5, new lineage 1) infection diagnosed by serum detection. J Infect Chemother. 2026;32(8):103017. doi:10.1016/j.jiac.2026.103017 ↩