Detection of #LaCrosse Virus #RNA in Clinical #Specimens Obtained from #Children with La Crosse Infection

 

Highlights

• Viremia in children with La Crosse Virus infection is transient; viral RNA was detected in only 3.2% of sera

• Detection of La Crosse Virus RNA in respiratory samples is slightly higher at 21.7% and may reflect the temporal distribution of the virus after infection

• NAAT has limited utility in routine diagnosis of La Crosse Virus encephalitis in children but may still be useful in cases with delayed seroconversion

Abstract

Background

La Crosse virus (LACV), a member of family Peribunyaviridae, genus Orthobunyavirus, is the leading cause of neuroinvasive arboviral infection in children in the United States. Diagnosis relies on detecting specific antibodies (IgG or IgM), a 4-fold titer rise or seroconversion, in patients with compatible presentations. NAAT used for LACV detection has largely been limited to mosquito, animal models or postmortem brain tissue. There is a lack of data on the performance of NAATs in clinical specimens from living patients.

Methods

Children who had positive arbovirus serology tests and a diagnosis of LACV encephalitis were identified. Remnant specimens including plasma, serum, CSF, throat swab (THT) or nasopharyngeal sample (NP) submitted to the laboratory for other diagnostic testing were retrieved and tested with LACV-PCR. Medical records were reviewed for demographics, presenting symptoms and test results.

Results

From June 2015 to October 2021, 61 patients had remnant specimens available for LACV-PCR and were included in this study. A total of 179 clinical specimens from these patients were tested, including 64 sera, 31 plasma, 33 CSF, 23 THT and 28 NP. Ten (5.3%) samples collected from 8 (13.1%) unique patients were positive for LACV RNA. The positive rates were 3.2%, 0, 6.5%, 3.5% and 21.7% for sera, plasma, CSF, NP and THT respectively.

Conclusion

There is limited utility of NAATs for diagnosis of LACV infection. NAATs may be useful in cases with delayed seroconversion or in immunocompromised individuals.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S1386653226000120?dgcid=rss_sd_all

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Detection of #WNV, #USUV and #Insect-Specific #Bunyaviruses in #Culex spp. Mosquitoes, #Greece, 2024

 

Abstract

Greece is one of the countries in Europe most affected by West Nile virus (WNV), and since 2010, when the virus caused a large outbreak with 197 human neuroinvasive cases, outbreaks occur almost every year. Mosquito surveillance is an indirect sign of virus circulation; therefore, the purpose of the study was the molecular detection of WNV in 45,988 C. pipiens s.l. mosquitoes collected during 2024 in four Regions of Greece and the genetic characterization of the virus strains. WNV was detected in 41 of 1316 (3.12%) Culex spp. mosquito pools. Next-generation sequencing was applied to the WNV-positive samples that had a high viral load. All WNV sequences belong to Cluster B of the sub-lineage Europe WNV-2A presenting a temporal clustering. The WNV infection rates varied highly across the Regions, regional units and months, being higher in Thessaly and Central Macedonia Regions, especially in July and September. All mosquito pools were also tested for Usutu virus (USUV), and one pool was found positive, with sequence clustering into the EU-2 lineage. A subset of mosquitoes (737 pools) was tested for additional viruses, and bunya-like viruses were detected in 6 pools with sequences clustering into four distinct subclades. The prompt detection of pathogenic viruses is helpful for the design of control measures, while the detection of insect-specific viruses provides insights into viral diversity and evolution.

Source: Viruses, https://www.mdpi.com/1999-4915/17/11/1414

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Emergence of #Oropouche Virus in Espírito Santo State, #Brazil, 2024

Abstract

Oropouche virus (OROV), historically endemic to the Amazon, had spread to nearly all Brazil states by 2024; Espírito Santo emerged as a transmission hotspot in the Atlantic Forest biome. We characterized the epidemiologic factors driving OROV spread in nonendemic southeast Brazil, analyzing environmental and agricultural conditions contributing to viral transmission. We tested samples from 29,080 suspected arbovirus-infected patients quantitative reverse transcription PCR for OROV and dengue, chikungunya, Zika, and Mayaro viruses. During March‒June 2024, the state had 339 confirmed OROV cases, demonstrating successful local transmission. Spatial analysis revealed that most cases clustered in municipalities with tropical climates and intensive cacao, robusta coffee, coconut, and pepper cultivation. Phylogenetic analysis identified the Espírito Santo OROV strains as part of the 2022–2024 Amazon lineage. The rapid spread of OROV outside the Amazon highlights its adaptive potential and public health threat, emphasizing the need for enhanced surveillance and targeted control measures.

Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/6/24-1946_article

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#Vector competence for #Oropouche virus: A systematic #review of pre-2024 experiments

Abstract {1}

The 2023–24 epidemic of Oropouche fever in the Americas and the associated ongoing outbreak in Cuba suggests a potential state shift in the epidemiology of the disease, raising questions about which vectors are driving transmission. In this study, we conduct a systematic review of vector competence experiments with Oropouche virus (OROV, Orthobunyavirus) that were published prior to the 2023–24 epidemic season. Only seven studies were published by September 2024, highlighting the chronic neglect that Oropouche virus (like many other orthobunyaviruses) has been subjected to since its discovery in 1954. Two species of midge (Culicoides paraensis and C. sonorensis) consistently demonstrate a high competence to transmit OROV (~30%), while mosquitoes (including both Aedes and Culex spp.) exhibited an infection rate consistently below ~20%, and showed limited OROV transmission. Further research is needed to establish which vectors are involved in the ongoing outbreak in Cuba, and whether local vectors and wildlife communities create any risk of establishment in non-endemic regions.

Abstract {2}

Oropouche virus has recently become an urgent threat to public health in Central and South America. OROV is mainly transmitted by biting midges; however, some public health agencies and scientific sources note that some mosquito species transmit the virus. We conducted a systematic review of literature prior to the current epidemic, and identified seven studies that experimentally tested the ability of vectors to become infected with, and transmit OROV (i.e., that assessed their vector competence). These studies have consistently found that biting midges become infected at higher rates than mosquitoes, which rarely transmit the virus. It is unclear which vectors are responsible for transmitting OROV in the current outbreak. Existing published data support the observation that biting midges are likely to be significant vectors compared to mosquitoes, which are comparatively incompetent. However, increased vector surveillance and pathogen testing, and additional vector competence experiments using current OROV strains, are urgently needed.

Source: PLoS Neglected Tropical Diseases, https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013014

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#Congenital #Oropouche in #Humans: Clinical Characterization of a Possible New #Teratogenic Syndrome

Abstract

Oropouche fever is caused by the Oropouche virus (OROV; Bunyaviridae, Orthobunyavirus), one of the most frequent arboviruses that infect humans in the Brazilian Amazon. This year, an OROV outbreak was identified in Brazil, and its vertical transmission was reported, which was associated with fetal death and microcephaly. We describe the clinical manifestations identified in three cases of congenital OROV infection with confirmed serology (OROV-IgM) in the mother-newborn binomial. One of the newborns died, and post-mortem molecular analysis using real-time RT-qPCR identified the OROV genome in several tissues. All three newborns were born in the Amazon region in Brazil, and the mothers reported fever, rash, headache, myalgia, and/or retro-orbital pain during pregnancy. The newborns presented with severe microcephaly secondary to brain damage and arthrogryposis, suggestive of an embryo/fetal disruptive process at birth. Brain and spinal images identified overlapping sutures, cerebral atrophy, brain cysts, thinning of the spinal cord, corpus callosum, and posterior fossa abnormalities. Fundoscopic findings included macular chorioretinal scars, focal pigment mottling, and vascular attenuation. The clinical presentation of vertical OROV infection resembled congenital Zika syndrome to some extent but presents some distinctive features on brain imaging and in several aspects of its neurological presentation. A recognizable syndrome with severe brain damage, neurological alterations, arthrogryposis, and fundoscopic abnormalities can be associated with in utero OROV infection.

Source: Viruses, https://www.mdpi.com/1999-4915/17/3/397

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Co-Circulation of 2 #Oropouche Virus #Lineages during #Outbreak, #Amazon Region of #Peru, 2023–2024

Abstract

We describe introduction of the 2022–2023 Oropouche virus lineage from Brazil, which has caused large-scale outbreaks throughout Brazil, into the Amazon Region of Peru. This lineage is co-circulating with another lineage that was circulating previously. Our findings highlight the need for continued surveillance to monitor Oropouche virus in Peru.

Source: US Centers for Disease Control and Prevention, https://wwwnc.cdc.gov/eid/article/31/4/24-1748_article

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