This work presents the pathology description, isolation and identification of canine herpesvirus (CHV-1) in Mexico, a virus that causes a generalized hemorrhagic infection in puppies from the canidae family. Methods: Isolates were obtained from puppies that died within the first four weeks of life and had lesions consistent with canine herpesvirus. Results: The main gross lesions were petechial and ecchymotic hemorrhages in kidneys, liver and lungs; proliferative interstitial nephritis; multifocal necrosis in liver and kidneys; and encephalitis with intranuclear inclusion bodies. Herpesvirus was confirmed through direct immunofluorescence, electron microscopy and polymerase chain reaction for DNA polymerase and glycoprotein B genes. Discussion: Eight strains were isolated and identified as canine herpesvirus corresponding to three of the working cases with gross and microscopic lesions very similar to those described in the literature; then, isolates were confirmed by PCR gene amplification, positive reactions on immunofluorescence and observations from electron microscopy. This work represents the first report of this disease, including gross and histological lesions, and confirmation by isolation and identification of the canine herpesvirus in Mexico.

Canine herpesvirus (CHV-1) causes disease associated with high mortality in infected puppies, which represents large financial losses for dog breeders. Since CHV-1 at the time of the study he had not been reported in Mexico, the main objective of this study was to determine the prevalence of antibodies against CHV-1 in canine kennels in the metropolitan area of Mexico City. A commercial enzyme-linked immunosorbent assay (ELISA) was used, and the results were compared to those of a viral neutralization test. The ELISA kit uses the complete viral particle as the antigen. The plaque reduction neutralization test was combined with the immunoperoxidase technique because of the low cytopathic effect of CHV-1. Neutralizing antibodies were also detected in 20 randomly selected samples. The prevalence of CHV-1 with ELISA was 87%. The concordance between ELISA and serum neutralization (SN) was 0.1129, the sensitivity of the ELISA against SN was 1.0 (100%), the positive predictive value was 0.39 (39%), and the negative predictive value was 1 (100%). These results show that ELISA is useful for monitoring the dog population for CHV-1; a positive test result requires confirmation with an SN test, and a negative ELISA result indicates a high probability of being SN-negative. The only variables that were statistically associated with CHV-1 prevalence were breed and kennel. A statistically significant relationship between the degree of ELISA and SN titer was obtained, with a confidence level of 95%. None of the clinical presentation factors was statistically significant. These results suggest that most of the canine population studied in Mexico is in a herpesvirus latency state.

La encefalitis equina del oeste (EEO) --al igual que las encefalomielitis del este (EEE) y venezolana (EEV)-- es una infección viral zoonótica que se transmite por mosquitos vectores. Su notificación debe ser inmediata y obligatoria. A pesar del nombre que se le ha dado, el caballo es sólo un huésped incidental. La manifestación clínica de las tres encefalitis es muy similar, por lo que se requiere de una correcta toma y envío de muestras al laboratorio para lograr un diagnóstico diferencial. Los ciclos de infección se presentan de dos formas: enzoótica, en la que el virus permanece por largos períodos circulando entre los huéspedes reservorios y el vector transmisor; y epizoótica, que involucra a los huéspedes incidentales y a los vectores transmisores. Los principales signos en caballos son alteración del comportamiento, dificultad visual, deambulación, caminata en círculos, dificultad en la deglución, ataxia, paresia, parálisis y convulsiones. No existe tratamiento, por lo que su manejo se enfoca a la terapia de soporte, con un pronóstico desfavorable, ya que la tasa de mortalidad (dependiendo de la encefalitis de la que se trate) puede llegar al 90%. La EEV es endémica en México y es la que presenta más riesgo, ya que, a diferencia de las otras dos, los caballos afectados suelen desarrollar viremia, por lo que pueden transmitir la enfermedad a través del piquete de mosco a otros huéspedes animales o al ser humano. En cuanto a las EEE y EEO aún no se han reconocido oficialmente en el territorio mexicano. Sin embargo, en marzo del presente año, se detectaron 44 casos de EEO en equinos en Nayarit. Dado que la única vacuna disponible y autorizada en México es la utilizada para prevenir la EEV, las medidas para disminuir el riesgo de infección por la EEE y la EEO se centran en alojar a los caballos en caballerizas controladas, especialmente durante los horarios de elevada actividad de los mosquitos.