The National Service for Health and Food Quality (Senasa) declared this Thursday a health emergency at the national level due to positive cases of alphavirus or equine encephalomyelitis. The disease is keeping Argentine health authorities on tenterhooks, who have received reports of horses with nervous symptoms as well as deaths in the provinces of Corrientes, Entre Ríos, Santa Fe and Córdoba in the last 72 hours.
Health authorities analyzed samples from horses that showed nervous symptoms or died. Equine encephalomyelitis is a disease caused by a viral infection that affects horses – such as horses, mares, donkeys, zebras and their hybrids – and in some cases can be transmitted to humans. Ximena Melón, director of animal health at Senasa, has confirmed that the cases are due to equine encephalomyelitis in its western variant, the same species diagnosed in the country in 1988.
“A meeting was held with the private sector and a comprehensive appeal was made to all representatives of the sector […] and a number of issues specifically related to this finding were discussed,” the official said in a video broadcast on the institution’s social networks. Meanwhile, Senasa is coordinating the immediate availability of vaccines for equine livestock through veterinary chambers across the country. For its part, the College of Veterinary Doctors of the Province of Santa Fe reported on its social networks that this is a situation in which Senasa has a duty to report and that any case of horses with nervous symptoms, even if suspected, will do so You must notify health authorities.
The warning has reached Uruguay, which is awaiting laboratory results to find out if there are cases of equine encephalomyelitis, although the disease has not yet been reported in humans, according to Agencia EFE. Paraguay also remains vigilant about the possible emergence of cases. In a statement released on Monday by the Ministry of Public Health and Social Affairs, Paraguayan authorities expressed that while no suspected or confirmed cases of the disease have been reported in the country, they have intensified surveillance of possible outbreaks and are urging the population to go to the doctor if you have any signs of the disease.
What is Equine Encephalomyelitis?
Equine encephalomyelitis is an exotic disease for Argentina, the last official registration was in 1988. It is a viral infection caused by a virus of the Togaviridae family and is transmitted through mosquito bites. Equine encephalomyelitis, as the name suggests, affects horses, horses, mares and donkeys and can cause severe encephalitis in animals and humans due to damage to the central nervous system.
Equine encephalomyelitis has three types: Eastern, Western and Venezuelan. These diseases are considered exotic in Argentina, the last official record is from 1988. According to Senasa, the mortality rate in diseased horses can reach 90% for the eastern variant and 20 to 30% for the eastern variant from the west, while that from Venezuela fluctuates in a larger range, which is between 40 and 90%. Animals that survive any of the diseases may suffer sequelae. In humans, the lethality is estimated to be lower.
How does the transfer take place?
This viral disease is transmitted from birds or small rodents to mosquitoes, which in turn infect horses and humans. According to the Santa Fe Province College of Veterinary Doctors, the mosquitoes that transmit the disease are generally found in warm and humid areas. They become infected by biting a horse or other animal infected with the virus. They can then transmit the virus to other horses or people through biting.
The viruses that cause eastern and western equine encephalomyelitis usually develop in birds and rodents and are then transmitted by mosquitoes. Medical research indicates that horses, humans and other mammals are intermediate hosts.
Equine encephalomyelitis transmission cycle. Santa Fe Provincial College of Veterinary Doctors 1st Circ.
Once the virus is infected, the incubation period of the disease, which is the time that elapses from infection to the appearance of clinical symptoms, is 5 to 14 days. Natural transmission between horses or from horses to humans has not been reported. Person-to-person transmission has also not been reported.
Can equine encephalomyelitis be transmitted to humans?
Yes, both horses and humans can become infected with the disease after being bitten by a mosquito infected with the virus. In humans, the viruses that cause all three types of equine encephalomyelitis can cross the placenta, and congenitally infected children have been reported in medical research, according to the document “Review of the Encephalomyelitis Virus Vaccination Strategy.” Equine of the East and the West in the Argentine Republic”. To date, the Ministry of Health has not announced any current human cases.
What are the symptoms in humans?
Eastern, Western, and Venezuelan equine encephalomyelitis have a number of slightly different signs and symptoms. In the case of western equine encephalomyelitis – which is currently occurring in Argentina – people usually show no symptoms or it develops mildly in adults, with no specific signs of the disease and few deaths. It is possible to present abruptly:
- Fever
- chills
- Headache
- nausea
- Vomit
- anorexia
- discomfort
- Occasionally respiratory symptoms may be observed
It is important to pay attention to the appearance of symptoms such as headache, irritability, focal neurological deficit, neck stiffness, confusion, sleepiness or lightheadedness, disorientation, tremor, seizures and paralysis as these are symptoms of Eastern equine encephalomyelitis that lead to it can cause significant harm to humans.
What are the symptoms in horses?
Horses show nervous signs and sometimes mortality. Other signs and symptoms in horses include:
- Forays
- Overexcitation
- depression
- Increased body temperature
- Lying down, which means the animal lies horizontally on the ground
Diagnosis, treatment and prevention of equine encephalomyelitis
Eastern, western and Venezuelan equine encephalitis are generally diagnosed by clinical examination of human and equine blood serum. There is currently no specific treatment for equine encephalomyelitis, but support is provided to maintain vital functions.
The most important measure to prevent the disease in humans is to use repellents and prevent the spread of mosquitoes. Horse owners are advised to contact their veterinarian regarding a vaccination schedule and to consult a specialist for horses exhibiting symptoms.
Argentine health authorities recommend vaccinating horses before transport or moving as a preventative measure, using repellents and keeping their stables clean to avoid mosquitoes that could infect them. If a horse shows symptoms of equine encephalomyelitis, it is important to have it examined by a veterinarian as soon as possible.
⚠️ WESTERN EQUINE ENCEPHALOMYELITIS
It is a viral disease that horses get through mosquito bites.
i️ We have created a microsite with clinical signs, recommendations and updated information on the epidemiological situation.
➡️https://t.co/XWu1WFQ4Ey pic.twitter.com/XaACYHoFpw
— Senasa Argentina (@SenasaAR) November 29, 2023
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