Text: Andre Juliau | FAPESP Agency
Rabies virus variants detected in bats are closely related to variants found in white-bellied marmosets (Callithrix jacos) in Ceará, raising an alert about the spread of the virus deadly to humans. Marmosets are very common in Brazil’s wild and urban areas, and are often hunted and kept as pets.
With support from FAPESP, the study was coordinated by researchers from Escola Paulista de Medicina da Universidade Federal de São Paulo (EPM-Unifesp). And the results were a statement In the Journal of Medical Virology.
In addition to the similarity between the variants found in the bats analyzed, the presence of rabies virus in insect-eating species of flying mammals caught the attention of researchers. Blood-feeding bats are known to be important hosts and vectors of the rabies virus.
“As of August this year, seven marmosets have been found positive for rabies. “In Ceará, the disease is endemic and we have a history of attacks on humans by Marmoset and rabies deaths, one of which occurred in May.”, in Fortaleza, and a doctoral student at EPM-Unifesp.
Souza points out death A 36-year-old farmer was attacked by marmosets in February in the municipality of Karius. The man only sought care in April, when symptoms began to appear, but he did not survive. Infection with the virus causes progressive encephalitis, an inflammation of the brain that leads to death in almost 100% of cases.
“The monkey fell in his yard with difficulty moving. The man tried to help him and was bitten. The animal already showed signs of paralysis, which is a symptom of rabies. A sick animal does not always show aggression and foaming at the mouth, which residents usually associate with rabies.” Sometimes, there are not even obvious symptoms,” explains the veterinarian.
Souza also warns not to touch bats and other wild mammals. When you find these dead animals, you must notify the municipality’s zoonotic disease service so that they can be sent for analysis.
Furthermore, the person who has had direct contact with the animal should seek medical attention so that rabies serum and vaccine can be administered, as the case may be.
“The incubation period for rabies virus is on average 45 days. Therefore, it is extremely important that the individual undergo post-exposure prophylaxis immediately. Without this treatment [soro e vacina antirrábicos]“When symptoms appear, the prognosis is usually fatal.” Ricardo Doris Carvalhoresearcher at EPM-Unifesp He supported By FAPESP and study coordinator.
The researchers analyzed 144 tissue samples taken from the brains of bats belonging to 15 species. The animals arrived in Lassen de Ceará between January and July 2022, as part of the National Epidemiological Surveillance Programme. As part of this programme, health professionals collect dead or symptomatic mammals in the country.
RNA was extracted from the samples to analyze the viruses present. The rabies virus genetic sequence was then compared with other genetic sequences deposited in public databases. Special tools have been used to trace the evolutionary history of existing viruses.
The first set of sequences was consistent with rabies virus variants found in two southeastern bat species in 2010, which are insectivorous. Tadarida brasiliensis that it Nectinomops laticodatus.
However, another group of variants, first found in bats (two species of insectivores and one species of frugivores), have a very close evolutionary relationship with the rabies virus discovered in white-tufted marmosets from northeastern Brazil. .
“Our results allow us to infer the presence of different variants of rabies virus, evolutionarily close and originally present in a particular animal, in other animals. This reveals complex dispersal dynamics.” [spillover] “And multiple viral transmission between families,” explains Dorias Carvalho.
As domestic animal vaccination has intensified, wild animals have become the primary source of human rabies in the Americas. The first marmoset-associated rabies death was reported in 1991, also in Ceará. Subsequently, 14 more deaths in the state were attributed to transmission by these primates.
Bats and monkeys, prominent actors in the rabies transmission chain in Brazil, play important ecological functions and suffer from habitat loss resulting from expanding cities and agriculture.
Bats, in particular, are important for the balance of ecosystems and are essential for seed dispersal, pollination, and pest control. “The best thing is to respect these animals and keep them in the wild,” Souza concludes.
Article Rabies virus variants from bats are closely related to variants found in marmosets (Callithrix jacos), which is a neglected source of human rabies infection in Brazil It can be read on: https://onlinelibrary.wiley.com/doi/abs/10.1002/jmv.29046.
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