A case of Borna virus infection reported in Bavaria…

In Germany, a very rare Borna virus infection was detected in Bavaria, in the district of Mühldorf am Inn. There is no more information. The disease, which is usually fatal, occurs only in a few isolated human cases in Germany.

Two other Borna virus infections have been known in the district in the last three years. According to the Bavarian State Office for Health and Food Safety (LGL), seven infections were reported in Germany in 2021, including five in Bavaria. On average, two infections are reported each year in Germany. However, scientists assume that the number of unreported cases is higher – with up to six cases per year.

Reminders in borna virus :

Borna virus is an enveloped RNA virus of the family bornaviridaeorder of mononegavirus. The Bornavirus genus includes eight species and 16 viruses.

  • five species include 12 avian bornaviruses;
  • one species includes a reptile virus;
  • two species include three mammalian viruses: the Bornavirus species of Mammalian 1 consisting of Borna disease viruses 1 and 2 (BoDV-1 and BoDV-2) and the Bornavirus species of Mammalian 2 where it is found in the Bornavirus species of Mammal 2 Variegated squirrel Bornavirus Bornavirus 1 (VSBV -1).

The white-toothed bicolor shrew (Crocidura leucodon) has been proposed as the natural reservoir of BoDV-1. The presence of BoDV-1 in reservoir hosts has been demonstrated in Germany, Austria, Switzerland and Liechtenstein.

Borna disease in animals

Borna disease was first described in the 18th century and is named after the town of Borna, near Leipzig, Germany, where an epizootic disease was described in 1885 in military horses with fatal neurological disease. Borna disease is most often reported in horses and sheep. However, many mammal species, including farm animals (cattle and goats), zoo animals (llamas, hippos, alpacas, monkeys, etc.) and, rarely, pets (dogs and cats) can also be affected. The disease has been observed in parrots, Canada geese, trumpeters and mute swans, canaries and reptiles.

In animals, the incubation period varies from two weeks to several months. Infection can lead to acute or subacute disease with meningoencephalitis, or mild manifestations with impaired or impaired nerve cell function. Paralysis is common and death occurs within 1 to 5 weeks in most animals. Recovery is possible with lifelong behavioral change.

Borna disease in humans

The first human infections demonstrated with a member of the Bornavirus genus were reported in 2015. The virus involved was VSBV-1. Between 2011 and 2013, three men from the same geographic area (Saxony-Anhalt, Germany) developed fatal progressive encephalitis and died 2 to 4 months after the onset of symptoms (fever and/or chills, confusion, unsteady gait, myoclonus and/or paresis). eye, progressive psychomotor retardation, and coma). The three men were breeders of variegated squirrels (Sciurus variegatoides) and traded their animals on different occasions. VSBV-1 was detected in central nervous system samples from the three patients, as well as in a squirrel that had been in contact with them. Plausible transmission routes were bites or scratches, but direct transmission to mucous membranes or inhalation of particles contaminated with feces or urine of infected animals cannot be ruled out. of infected animals is not excluded.

In 2018, Germany reported four human cases of encephalitis or acute encephalopathy associated with infection by BoDV-1. Three of the cases involved a group of solid organ recipients who became ill approximately 100 days after a single-donor transplant in southern Germany (two recipients died) and an additional case of BoDV-1 encephalitis, also deceased, was found in the south. from Germany. Aside from the fact that these three cases received organs from a single donor, no other common risk factors were identified.

The overall incidence of bornavirus-induced encephalitis in humans is unknown. However, a retrospective study carried out in the endemic area of
the German federal state of Bavaria has demonstrated that BoDV-1 can be responsible for a significant proportion of fatal encephalitis cases. Therefore, all cases of severe encephalitis of uncertain cause should be tested for this virus, particularly in endemic regions. However, the absolute number of infections and therefore the risk of infection is estimated to be very low.

Infection through contact with an infected white-toothed shrew or its droppings may be suggested, however, the exact route of transmission is still unknown. Natural human-to-human, horse-to-horse, or horse-to-human transmission can be excluded based on current knowledge. The virus is responsible for neurological disorders. The so-called classic Borna virus triggers brain inflammation that ends fatally in almost all cases. Survivors often retain severe sequelae

References: (1) ECDC. 26 March 2018. Acute encephalitis associated with infection with Borna v diseaseiris 1, Germany. (two) Touch et al. BMC Infectious Diseases (2021) 21:787

Source: News of the outbreak today.

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