Heartland virus : a novel and emerging tick-borne encephalitis Virus Heartland : una nueva y emergente encefalitis transmitida por garrapatas

Amblyomma americanum and Dermacentor variabilis ticks have been involved as a vector of HRTV in USA. The vertebrates amplification hosts associated with enzootic maintenance of the HRTV have been studied in Missouri. Neutralizing antibodies to HRTV in raccoons (42.6%), horses (17.4%), white-tailed deer (14.3%), dogs (7.7%) and opossums (3.8%) were identified. No antibodies were found in birds. The high seroprevalence associated with local abundance of white-tailed deer and raccoons demonstrated these species may be an amplification hosts. Virus isolation experiments from sera and ticks to detect HRTV virus were unsuccessful (2).


EDITORIAL
Rev.MVZ Córdoba 21(1):5099-5101, 2016.ISSN: 0122-0268 Heartland virus (HRTV) is a Bunyaviridae, phlebovirus that it has recently emerged as the causative agent of human disease characterized by thrombocytopenia and leukopenia in the United States and China.It seems to be the HRTV has been also reported in China, Japan and Korea.Recently the first fatal case of HRTV disease in an 80-year-old Tennessee resident was reported (1).
Amblyomma americanum and Dermacentor variabilis ticks have been involved as a vector of HRTV in USA.The vertebrates amplification hosts associated with enzootic maintenance of the HRTV have been studied in Missouri.Neutralizing antibodies to HRTV in raccoons (42.6%), horses (17.4%), white-tailed deer (14.3%), dogs (7.7%) and opossums (3.8%) were identified.No antibodies were found in birds.The high seroprevalence associated with local abundance of white-tailed deer and raccoons demonstrated these species may be an amplification hosts.Virus isolation experiments from sera and ticks to detect HRTV virus were unsuccessful (2).
In 2012 in Missouri farms, 56.428 ticks of Amblyomma americanum and Dermacentor variabilis were collected.By using RT-PCR (reverse transcription-polymerase chain reaction), several nymphs pools of A. americanum were positive, 8 pools yielded viable viruses.Sequence data from the nonstructural protein of the small segment demonstrates that tick strains and human strains are very similar, ≥97.6% sequence identity (3).
This was the first study to isolate HRTV from ticks and they seem to be implicating as potential vectors.Amblyomma americanum possible to becomes infected by feeding on viremic hosts during the larval stage, and transmission to humans occurs during the spring and early summer when nymphs are abundant and actively host seeking (3).

Heartland virus: a novel and emerging tick-borne encephalitis
Virus Heartland: una nueva y emergente encefalitis transmitida por garrapatas Recently, there was a report of the first fatal case of HRTV disease in an 80-year-old Tennessee resident.The patient was admitted at the clinic with fever, confusion, leukopenia, and thrombocytopenia and developed multiorgan failure and hemorrhage.The patient died on hospital day 15, and autopsy specimens were tested for various pathogens as part of an unexplained death evaluation.HRTV antigens were detected in postmortem spleen and lymph nodes by immunohistochemistry, and HRTV was detected in premortem blood by RT-PCR and the virus was isolated in cell culture (6).
Because HRTV is an emerging virus, laboratory diagnosis is incipient yet, the diagnosis in Colombia and Latin America is extremely difficult.However, detection of viral RNA by RT-PCR on blood or tissue can be carry out, hence a ≥4-fold rise antibody titers by PRNT in acute and convalescent serum specimens can be carry out (5).
Like other viruses, no vaccine or medication is available to prevent or treat Heartland virus disease.Because the virus possible is transmitted through infected ticks or other arthropods, prevention depends on using insect repellents, wearing long sleeves and pants and performing tick checks after spending time outdoors (5).
In Colombia especially in the tropics, there are strong evidence of Amblyomma sp and Dermacentor ticks thus, it is likely that HRTV is circulating.The fatal cases in USA demonstrate En una encuesta de seroprevalencia realizada en Minnesota, EE.UU, en muestras de sangre de animales domésticos para determinar anticuerpos para HRTV.Los anticuerpos contra nucleoproteínas del virus fueron encontrados en un 10% -18% de las muestras provenientes de ganado, ovejas, cabras, ciervos y alces en el condado de Minnesota (4).
En Colombia, especialmente en los trópicos, hay una fuerte evidencia de Amblyomma sp y Dermacentor por lo tanto, es probable que HRTV esté circulando.Los that HRTV infection can cause severe disease and death.In Colombia, tick´s population are endemic affecting animals and people, the dissemination of the HRTV in Colombia is likely because the favourable geoclimatic conditions (7).
Finally, tick-borne viruses that cause diseases in humans mainly belong to 3 families: Bunyaviridae, Flaviviridae, and Reoviridae, we actually in Latin America do not know about this vector borne disease, it is necessary to carry out several surveys to establish the prevalence of those viruses in the vectors and humans as well.
casos fatales en EE.UU.demuestran que la infección HRTV puede causar una enfermedad grave y la muerte.En Colombia, la población de garrapatas es endémica y afecta a los animales y a las personas, la difusión de la HRTV en Colombia probablemente sea debido a las condiciones geoclimáticas favorables (7).