Bluetongue is a non-contagious, viral disease affecting both domestic and wild ruminants with a high morbidity and mortality, transmitted by the bites of Culicoides midges. The virus belongs to the Sedoreoviridae family and consists of 24 recognized serotypes.
Bluetongue virus (BTV) is endemic in tropical and subtropical regions. However, the global distribution and nature of BTV infection has changed significantly in recent years, and climate change has been identified as a potential cause.
Since 2006, BTV has expanded further into Western Europe reaching as far north as 58° N, representing a new wave of expansion.
Increase of vector spread
- Higher temperatures
- Less rainfall
- Stagnant water
Subclinical reservoirs infected
Hosts with few or no signs or symptoms of infection can transmit the virus to the midges, which then infect other animals.
Introduction of susceptible animals in endemic areas
TRANSMISSION OF BLUETONGUE VIRUS
The majority of Bluetongue virus (BTV) transmission takes place quietly among host animals that have developed resistance to the disease. Cattle serve as the primary reservoir in most areas, often carrying the virus without showing clinical symptoms and occasionally experiencing extended periods of viral presence in their bloodstream, lasting up to 100 days.
After biting an infected animal, the midge ingests the virus, leading to infection in the midge’s gut cells. The virus then replicates within these cells, escapes into the insect’s body cavity (haemocoel) and proceeds to infect and replicate within the salivary glands. Only after this process is complete can the virus be transmitted to a new host.
- Biological Vector
Infected midges can be carried by winds up to 300 km (180 miles)
- Transplacental transmission
This kind of transmission only happens in serotype 8
SIGNS AND SYMPTOMS OF BLUETONGUE
Clinical cases of BTV occur mainly in sheep, while subclinical infection (with no signs) seem to predominate in most other species.
- Hemorrhage & Edema
- Oral and nasal lesions: tissue ulceration, salivation, nasal discharge, swelling of lips, tongue and jaw, cyanosis of the tongue (blue tongue)
- Pedal lesions: Coronary inflammation and lameness
- Temporary infertility and miscarriages
- Weight loss
Cases of subclinical disease make it difficult to diagnose Bluetongue disease and allow the virus to replicate and spread.
There are also other indirect costs like having to slaughter animals as it is difficult to control the disease. Asymptomatic animals are carriers and reservoirs of the virus, causing the spread of the bluetongue virus.
DR. FRANCISCO JAVIER ORTEGO
Researcher at Animal Health Research Center (CISA-INIA)
Dr.Francisco Javier Ortego completed his PhD dissertation at Hospital Ramón y Cajal in Madrid under the supervision of Dr. Rafael Fernández Muñoz. He then pursued two postdoctoral studies for a total of 10 years, first at Yale University in the US and then at the National Center for Biotechnology of the CSIC in Madrid, where he held a reinstatement contract from the Ministry of Education and Science and an I3P contract from the Ministry of Science and Technology.
In February 2005, he joined the Animal Health Research Center (CISA-INIA/CSIC) as a Ramón y Cajal researcher and later became a Full Scientist of OPIs in 2008. Since then, he has been conducting research in the field of developing and optimizing universal vaccines against arboviruses relevant to animal health, focusing on the bluetongue and African horse sickness viruses.
In 2022, he participated in three projects, two as a Co-IP, which aimed to create and asses COVID-19 vaccines. Additionally, he served as Deputy of the National Agency for Evaluation and Prospecting (ANEP) from 2015 to 2017, and later as coordinator of the Livestock and Aquaculture (GYA) sub-area of the AEI from 2017.