Baggio–Yoshinari Syndrome (BYS) is an emerging Brazilian tick-borne infectious disease that clinically mimics Lyme Disease (LD) present in the Northern Hemisphere. LD is caused by spirochetes belonging to the Borrelia burgdorferi sensu lato complex and transmitted by Ixodid ticks of complex Ixodes rticinus. On the contrary, BYS is transmitted by hard Ixodid ticks of the genera Amblyomma, Rhipicephalus and Dermacentor. In 1992, the first cases of BYS were described in patients that developed EM rash, flu-like symptoms and arthritis after tick bite episodes. Since these findings, research in BYS has been developing for more than 30 years and shows that its epidemiological, clinical and laboratorial features are different from LD. Borrelia burgdorferi was never isolated in Brazil. In addition, specific serologic tests have shown little positivity. Furthermore, peripheral blood analysis of patients using electron microscopy exhibited structures resembling spirochete-like microorganisms or the latent forms of spirochetes (L form or cell wall deficient bacteria). For these reasons, Brazilian zoonosis was defined as an exotic and emerging Brazilian infectious disease, transmitted by ticks not belonging to the Ixodes ricinus complex, caused by latent spirochetes belonging to the B. burgdorferi sensu lato complex with atypical morphology. The Brazilian ecosystem, combined with its ticks and reservoir biodiversity, possibly contributed to the origin of this new zoonosis, which emerged as a result of the passage of B. burgdorferi through exotic vectors and reservoirs.

Lyme borreliosis is a disease transmitted by ticks to mammals, especially in horses and humans. Caused by a spirochete Borrelia burgdorferi, it can result in lameness, arthritis, carditis, dermatitis and neurological signs. Anaphylactoid reactions are severe responses caused by direct action of substances (drugs, toxins), which can pose risks to life. Still poorly documented in horses, these reactions are caused by the effects of inflammatory mediators such as histamine, kinins and arachidonic acid metabolites. The last two are the most clinically relevant for the species. The simultaneous occurrence of anaphylactoid reaction in two horses experimentally infected by Borrelia burgdorferi undergoing intravenous treatment with ceftriaxone sodium is reported. It was administered 4.7 × 10⁸ spirochetes intradermal and subcutaneous applications in both horses to evaluate clinical aspects of the Lyme disease, 95 days before the application of sodium ceftriaxone. During the administration, one horse (a gelding) showed immediate and severe anaphylactoid symptoms such as urticaria, dyspnea, tachycardia, and eyelid edema, which were controlled by injecting dexamethasone. After 1 day, it expressed signs of abdominal discomfort, caused by severe bloat, which was treated surgically via celiotomy. Subsequently, this gelding had piroplasmosis and severe anemia, requiring treatment with an antimicrobial and blood transfusion. Second horse (a mare) showed signs of hypotension during the application of the antibiotic, which disappeared only when the application was interrupted. Days after the event, the mare developed moderate large colon bloat, which was treated with medication only. Subsequently the mare was evolved into the prodromal phase of laminitis in one of the forelimbs, which was treated for 10 days with non-steroidal anti-inflammatory and rheology modifying drugs and cryotherapy. From the two cases presented here, it does appear that sodium ceftriaxone can induce anaphylactoid reactions in horses infected by Borrelia burgdorferi, which may evolve into colic syndrome, laminitis and the occurrence of opportunistic infections. However, further evidence should be collected in order to draw definite conclusions.

Compared to classic Lyme disease (LD), Baggio–Yoshinari syndrome (BYS) has the following distinctive characteristics: it is transmitted in the Amazon area and Northeast, Central-West, Southeast, and South regions of Brazil by hard ticks, notably Amblyomma cajannense or Rhipicefalus sp. The absence of Ixodes sp. ticks in areas at risk of BYS in Brazil is probably the main reason for the disease’s differences from LD in the United States, Europe, and Asia. Biodiversity and climate probably favor the formation of atypical pleomorphic Borrelias, which have not yet been cultivated or isolated. Clinically, the first manifestation of BYS is the erythema migrans as in the classic forms of Lyme disease, but BYS is distinguished from LD by its prolonged clinical evolution, with a high frequency of relapses and the appearance of autoimmune manifestations. Prevalent symptoms are headache and erythema nodosum. Five clinical cases of BYS in patients who contracted the disease in the Brazilian Amazon rainforest are described here. This syndrome should be considered among differential diagnoses in patients bitten by ticks in Brazil who present with erythema migrans and/or headache. It is important to pursue an early diagnosis because symptoms respond well to antibiotics in the early stages; if treatment is started late, a chronic course with articular and neurological sequelae can be detected.

Resultados de 30 anos de pesquisas sobre a síndrome de Baggio-Yoshinari (SBY) no Brasil levantaram inúmeras controvérsias sobre as zoonoses causadas pela Borrelia burgdorferi no país, em comparação com os descritos nos demais continentes do hemisfério norte. Foi proposto pela primeira vez que um mesmo agente etiológico, quando da sua passagem por carrapatos de espécies diferentes, origina diferentes enfermidades. Afirma-se como dogma que carrapatos transmissores da doença de Lyme (DL) pertençam necessariamente ao complexo Ixodes ricinus; portanto, trata-se de heresia dizer que a borreliose brasileira é transmitida por outras espécies de carrapatos, como os pertencentes aos gêneros Amblyomma, Rhipicephalus e Dermacentor. Outras heresias ou quebras de dogmas foram propostas durante as pesquisas científicas na Faculdade de Medicina da Universidade de São Paulo-SP, como a presença de B. burgdorferi mutante desprovida de flagelos e de outras proteínas da membrana externa bacteriana, conhecidas como Osps, originando espiroquetas incultiváveis em meio BSK e que seriam desprovidas de movimentos helicoidais, exibindo morfologias de cistos ou borrelias atípicas. Este agente etiológico suprimido de múltiplos genes, e consequentemente de proteínas, teria originado uma zoonose exótica no Brasil, conhecida como SBY, enfermidade de natureza infectorreacional, com epidemiologia, clínica e laboratório exóticos, muito distinto da DL. Atualmente, há um dilema entre os médicos brasileiros quanto a aceitar e praticar as heresias propostas na SBY ou seguir os dogmas propostos pelos pesquisadores estudiosos da DL nos Estados Unidos da América, Europa e Ásia. Pior, por negligência, muitos profissionais da saúde ainda insistem em negar a existência da borreliose no Brasil, acarretando sérios prejuízos aos nossos doentes. Trata-se de um breve artigo crítico, pois o manuscrito em detalhes consta como capítulo no recém-publicado livro da Sociedade Brasileira de Reumatologia. Unitermos: Doença de Lyme-símile. Doença de Lyme. Borreliose. Borrelia burgdorferi. Carrapatos.