Stillborn infants carried the Ljungan virus
[PRESS RELEASE, 6 November 2008] Scientists suspect that the Ljungan virus causes foetal death in humans. The hypothesis is supported by a new doctoral thesis from Karolinska Institutet. The postgraduate student Annika Samsioe has investigated fifteen cases of foetal death and has diagnosed Ljungan infection in ten of them.
Small wild rodents are the reservoir of the Ljungan virus, which can also infect humans. The now presented doctoral thesis shows that the Ljungan virus, in combination with stress, can cause severe malformations and foetal death in laboratory animals.
The discovery prompted the scientists to move on to investigate a potential connection between Ljungan virus and unexplained cases of foetal death during the end of pregnancy in humans. The number of stillborn foetuses follows in a striking way the fluctuating rodent density in the north of Sweden. In southern Sweden, where the number of rodents does not fluctuate, there is no periodic variation in the number of stillborn foetuses. Furthermore, the scientists discovered the presence of Ljungan virus in the placenta of children from several previously unexplained cases of foetal death.
I have conducted two studies in which a total of fifteen cases of unexplained foetal death during pregnancy occurring at week 28 or later have been investigated. The results suggest that the Ljungan virus is involved, says Annika Samsioe, midwife and doctoral student at the Department for Clinical Research and Education, Stockholm South General Hospital, Karolinska Institutet.
In one of the studies the scientists found Ljungan virus in the placenta of five out of ten of the cases examined. In four of these Ljungan virus was found in the stillborn children as well. A control group of twenty women with normal pregnancies showed that each of their placentas was free from the virus. In a corresponding follow up study the scientists found Ljungan virus in the placenta and/or children of all of the five cases examined.
Through her studies, Annika Samsioe has been able to show that Ljungan virus may cause diabetes in animals. Behind the results of the thesis are new methods of diagnostics, developed in cooperation between scientists in Sweden and the USA. The virus was discovered in the 1990s and has been isolated in both Europe and America. The virus seems to have worldwide distribution.
What role the Ljungan virus is playing in cases of foetal death and various other illnesses is still, to a great extent, an unsolved puzzle. We now hope for an increase of international attention and intensified research of the subject, says Annika Samsioe
Ljungan virus a novel pathogen. Effects on the pregnant female and her offspring
Department for Clinical Research and Education, KI SÖS