Under-recognized rodent-borne arenavirus threatens fetal brain development in urban settings

Lymphocytic choriomeningitis virus (LCMV), a rodent-borne arenavirus first identified in 1933, has long been regarded as a low-risk pathogen tied to rural rodent exposure. A comprehensive review published in Virology Journal argues that this view no longer matches the evidence. Drawing on recent epidemiological and clinical data, the authors describe LCMV as a neglected zoonotic agent of growing recognition in urban, non-endemic regions, with particularly serious implications for pregnant women and their fetuses. The review, shared early as a peer-reviewed accepted manuscript that remains subject to further editorial edits, examines the virus’s evolving epidemiology, clinical spectrum, diagnostic challenges, and public health consequences, with congenital disease at its center.

The most striking evidence comes from urban seroprevalence work. The 2026 Philadelphia study reported immunoglobulin G (IgG) seropositivity rates of 2.4–2.7 percent among urban pregnant women, with exposure strongly linked to neighborhood deprivation indices, substandard housing, and socioeconomic vulnerability. Comparable patterns of continued viral circulation have been documented across Europe, including Germany, Hungary, and Bulgaria, as well as in Australia and Brazil. In the United States, researchers have identified a novel, apparently more virulent strain in New Mexico. Together, these findings challenge the traditional framing of LCMV as a rural pathogen and suggest substantial circulation in cities, where pregnant women may be exposed without recognizing any specific risk.

The review attributes the virus’s changing epidemiology to several converging forces. Urbanization, climate change, and global migration are reshaping the interface between humans and rodent reservoirs, while improved molecular diagnostics, including reverse transcription polymerase chain reaction (RT-PCR) and metagenomic next-generation sequencing (mNGS), are detecting infections that older surveillance methods missed. The authors present LCMV as an example of how neglected zoonotic pathogens can move into new populations and settings in an era of rapid urbanization and global connectivity, and how better laboratory tools are revealing a burden that was previously under-recognized rather than absent.

Congenital LCMV infection can produce devastating fetal outcomes. The review describes a classic tetrad of chorioretinitis, hydrocephalus, microcephaly, and periventricular calcifications, and notes that affected infants frequently experience significant long-term neurodevelopmental disabilities, including intellectual impairment, seizures, motor deficits, and sensory loss. The virus exhibits strong placental tropism, and the timing of maternal infection critically influences the severity of fetal brain injury, making the gestational age at exposure a key determinant of outcome. Fetal neuroimaging, using serial ultrasound and magnetic resonance imaging (MRI), plays a central role in both diagnosis and prognosis, allowing clinicians to track the evolution of brain injury during pregnancy.

On the diagnostic front, the review analyzes the respective strengths, limitations, and optimal timing of RT-PCR, mNGS, and serological testing for immunoglobulin M (IgM) and IgG. Molecular methods can identify active infection, while serology documents past exposure, and each modality carries constraints that affect interpretation at different stages of pregnancy. Building on this analysis, the authors propose a practical risk-stratified prenatal screening algorithm together with a serial fetal neuroimaging protocol, aimed at identifying high-risk pregnancies and monitoring fetal brain development in affected cases.

Treatment options remain limited. Current therapeutic care for congenital LCMV infection is supportive, as no approved specific antivirals are considered safe for use in pregnancy. The review therefore places considerable weight on prevention, addressing strategies to reduce rodent exposure, travel medicine considerations for pregnant travelers, and guidance for migrant populations who may face elevated exposure risk. The authors call for increased clinical awareness, enhanced surveillance, targeted screening in high-risk groups, and investment in antiviral and vaccine development to reduce the burden of this neglected congenital infection. In their assessment, LCMV exemplifies an under-recognized arenaviral pathogen capable of causing significant maternal–fetal morbidity, and closing the awareness gap is presented as an urgent priority for clinicians and public health systems alike.

Subject of Research: Review of lymphocytic choriomeningitis virus epidemiology, congenital disease, diagnostics, and prevention

Article Title: Lymphocytic choriomeningitis virus: an under-recognized arenaviral threat with important maternal–fetal implications

Article References: Kambham, S., Rajeshwara, S., Manzoor, L., Khalid, F., Alupei, E., Faiz, D., ElShabrawi, M., & Das, A. (2026). Lymphocytic choriomeningitis virus: an under-recognized arenaviral threat with important maternal–fetal implications. Virology Journal. https://doi.org/10.1186/s12985-026-03317-9

Image Credits: AI Generated

DOI: 10.1186/s12985-026-03317-9

Keywords: LCMV, arenavirus, congenital infection, zoonosis, pregnancy, seroprevalence, hydrocephalus, chorioretinitis, RT-PCR, metagenomic sequencing, fetal neuroimaging, public health