In 2024, the Pan American Health Organization\/World Health Organization reported rising OROV cases across the Americas, including areas with no previous evidence of circulation (3<\/a>). Health officials linked this geographic expansion to severe clinical outcomes, including fatalities, vertical transmission, fetal loss, and microcephaly (4<\/a>). Studies from Brazil identified a novel recombination event in OROV genomes (5<\/a>).<\/p>\n PTV belongs to the Phenuiviridae family, Phlebovirus genus. This highly diverse genus encompasses numerous species globally distributed and transmitted by vectors like sandflies and ticks (6<\/a>). Key members include Toscana virus and Rift Valley fever virus, which cause epidemics and neurologic disease across the Mediterranean Basin, Europe, and the Middle East (7<\/a>). Reports from the Americas have identified Phlebovirus species in Brazil, Peru (8<\/a>), Colombia (9<\/a>) and Panama (10<\/a>), although PTV appears to be reported only in Panama. Human infections, mainly detected in metropolitan areas of Panama, cause nonspecific febrile illness characterized by fever, headache, weakness, and retro-orbital pain (10<\/a>).<\/p>\n In 2023\u20132024, the Gorgas Memorial Institute (Panama City, Panama) analyzed 3,589 serum samples. After a Pan American Health Organization\/World Health Organization alert on rising regional OROV incidence and because of the lack of confirmed cases in Panama, we retrospectively tested a subset (24%) of dengue virus (DENV)\u2013negative samples from that set for OROV by reverse transcription PCR (11<\/a>). We later integrated this assay into a broader diagnostic algorithm for samples testing negative for DENV, Zika virus, and Ccikungunya virus, which included testing for Alphavirus, Orthoflavivirus, and Phlebovirus (Appendix 1<\/a>).<\/p>\n Through this surveillance, we identified an OROV-positive case from August 2024. The patient, a 31-year-old male environmental officer stationed in a forested area of the Soberan\u00eda National Park, Panama, sought treatment for an acute febrile syndrome characterized by severe frontal-occipital headache, chills, arthralgia, and marked asthenia. The man underwent an initial clinical evaluation at a primary healthcare facility, where the result of a dengue NS1 antigen test was negative. Treating clinicians reported no neurologic manifestations or relapses. Health officials conducted contact tracing, covering the patient\u2019s residence and workplace, collecting serum and urine samples from 36 contacts. Twelve symptomatic persons underwent testing for OROV, DENV, Zika virus, chikungunya virus, Orthoflavivirus, Phlebovirus, and Alphavirus (Table 1<\/a>). Of those, 1 contact tested positive for the Phlebovirus genus, with symptoms including fever, chills, myalgia, arthralgia, headache, retroorbital pain, and conjunctivitis.<\/p>\n Figure<\/p>\n Figure<\/a>. Concatenated maximum likelihood phylogenetic tree of 3 OROV segments from a patient found in study of detection of OROV and Punta Toro virus infections by enhanced surveillance, Panama, 2023\u20132024. The…<\/p>\n We sequenced aliquots from both positive samples (OROV and Phlebovirus genus) using an in-house metagenomic approach (A. Martinez et al., unpub. data, https:\/\/dx.doi.org\/10.17504\/protocols.io.36wgq6545lk5\/v1<\/a>) (Appendix 1<\/a>), yielding a complete OROV genome (GenBank accession nos. PV942050\u20132) (Table 2<\/a>). We performed phylogenetic analysis using the Nextstrain OROV database (https:\/\/github.com\/nextstrain\/oropouche<\/a>), which placed the sample at the basal node of the BR-2015\u20132024 clade (5<\/a>), notably separated from the sequences circulating in the Brazil outbreak (Figure<\/a>).<\/p>\n We performed a comparative analysis of OROV using the Panama sequence (hOROV\/Panama\/A003066\/2024), recent Brazil sequences (OROV\/Saul\/17225\/2020, LACENAM_ILMD_3228ZCF, and ILMD_TF29; GenBank accession nos. PP154170\u20132), and the ancestral BeAn19991 strain as reference. The Panama sequence showed multiple amino acid substitutions across structural and nonstructural proteins sharing 96.8% amino acid identity for the large (L) segment, 97%\u201399% for the medium (M) segment, and 98%\u2013100% for the small (S) segment with BeAn19991. The Panama sequence also shared 99% amino acid identity for the L segment, 98%\u201399% for the M segment, and 100% for the S segment with the Brazil sequences (Appendix 1<\/a> Figure 1). We theorized that the differences may influence viral replication or transcription efficiency (K.B. Gunter et al., unpub. data, https:\/\/dx.doi.org\/10.1101\/2025.08.02.668287<\/a>).<\/p>\n Further testing identified the Phlebovirus genus\u2013positive sample as PTV (GenBank accession nos. PV942053\u20135) (Appendix 1<\/a> Figure 2; Appendix 2<\/a>). Compared against the prototype strain (GenBank accession nos. KP272028\u201330), amino acid identity was 87% for the L segment, 94% for the M segment, and 95%\u201397% for the S segment. Comparison with a 2004 sequence (GenBank accession nos. KP272031\u20133) showed amino acid identity as 99% with the L segment, 99% with the M segment, and 98%\u201399% with the S segment (Appendix 1<\/a> Figures 3, 4).<\/p>\n Before the OROV outbreak that began in January 2025 in Panama, the last documented case occurred in 1989 in Bejuco, a coastal community \u224835 miles west of Panama City, a region surrounded predominantly by mature broadleaf forest at the time (2<\/a>). The OROV case we identified was likely acquired in a similar ecologic setting, at the interface between the metropolitan region and the Soberan\u00eda National Park. The geographic proximity between Bejuco and Soberan\u00eda National Park (22\u201325 miles) suggests shared ecologic characteristics and supports the hypothesis of ongoing cryptic OROV circulation before the 2025 cases reported in Dari\u00e9n province.<\/p>\n Although the absence of genomic data over the intervening decades limits reconstruction of OROV\u2019s full evolutionary history in Panama, our case provides valuable evidence suggestive of persistent, undetected sylvatic circulation. The Panama OROV sequence shows marked amino acid divergence from the ancestral BeAn19991 strain, especially in the L and M segments, and fewer differences relative to strains currently circulating in Brazil and South America, which have been reported since 2022 (5<\/a>). Those changes are similar to mutations reported in recent studies (G.C. Scachetti et al., unpub. data, https:\/\/dx.doi.org\/10.1101\/2024.07.27.24310296<\/a>). The differences between the Panama strain and newly described OROV reassortants suggests ongoing adaptive processes, driven potentially by local selective pressures or prolonged cryptic circulation in Panama. Sporadic retrospective OROV detections in Brazil from dengue surveillance samples mirror this context (12<\/a>).<\/p>\n![\"Concatenated](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2026\/01\/25-1224-F1-tn.jpg\")
<\/p>\n