I’m going to tell you something that may surprise you. It is not usual for a conversation on a social network to end up leading to a scientific publication. Even less if this is in one of the most prestigious magazines in its area: Emerging Infectious Diseases.
The story involves an emerging disease, Crimean-Congo hemorrhagic fever (CCHF). This is the description of the first known case of this disease in Spain so far, and we have discovered it thanks to Twitter. What do not believe me? Keep reading.
Crimean-Congo hemorrhagic fever, caused by a virus (CCHFV) that is transmitted by ticks, produced three cases in Spain last year, all in the province of Salamanca. They weren’t the first: there were two more in 2018 and another two in 2016.
Last month there was one more case, also admitted to a hospital in Salamanca. It is a very serious disease that causes death in an appreciable percentage of cases. Of the eight cases cited, three died: the first in 2016, another in 2018 and a third in 2020.
The two of 2016 were considered the first cases of this disease in Spain. The first of them was a 62-year-old man, who was presumably infected through a tick bite during a walk in the mountains in southern Ávila. He was admitted to a hospital in Madrid where he died, but infected a nurse who cared for him, who suffered the disease but, fortunately, managed to overcome it. In 2018 there was a fatal case in Badajoz, related to hunting activities.
The presence of this virus in Spain has been known since 2010. That year, infected ticks were found parasitizing deer on a hunting farm in the province of Cáceres, very close to the border with Portugal. Subsequent studies have located the virus circulation areas in some regions of the center and south of the peninsula, as can be seen in the following map, where the places where human cases occurred are also indicated.
It must be said that this disease, which is endemic in certain areas of sub-Saharan Africa and central Asia, is expanding in eastern Europe. Spain is the only country in Western Europe that has declared cases of this disease for now.
But let’s get back to our story. Last summer a case of this disease was detected in Spain, which had some diffusion in the media, and I commented on Twitter:
It was raining in the wet: in addition to the pandemic coronavirus, we had an active West Nile virus fever outbreak in Andalusia, which so far has been the worst we have suffered in Spain. Interest in alerts for emerging viruses was on the rise and my tweet was quite popular.
Among the comments he received was a very special one. One person told me that he had suffered a very serious illness after being bitten by a tick in 2013. He also told me that the bite occurred in the south of Ávila and that it was treated in Salamanca.
He asked me if it was possible to know if it had been Crimean-Congo hemorrhagic fever. Of course you could tell. That was very likely. At that very moment I had the feeling that, indeed, it could be a case that would have gone unnoticed. If this were the case, it would be the first case described in Spain, three years before the official debut of this disease in our country.
To investigate this possibility, I contacted the medical team that treated her at the University Hospital of Salamanca. There, that case had attracted attention due to its seriousness: a hemorrhagic disease with a possible origin from a tick bite , which left an uncertain diagnosis.
Pathologies caused by infectious agents transmitted by ticks were considered, but at that time no one thought about Crimean-Congo fever. In 2013 it was an unknown disease in Spain except for an important detail that I mentioned before: this pathogen had been detected three years earlier in ticks from a rural area of the province of Cáceres.
I contacted the national reference laboratories of the Carlos III Health Institute (serology and arboviruses and imported viruses). There they have been studying evidence for years and making the diagnosis of this disease in Spain.
We ask for a new blood sample to test for antibodies. The result was unequivocal, by two different techniques: the patient had been infected with CCHFV. We also verify that the antibodies against this disease remain in the blood for a long time, at least seven years. It was the eureka moment of this story: the first cases so far in Spain dated from 2016. This had happened in 2013!
It became, chronologically, the first case (known so far) of Crimean-Congo hemorrhagic fever in Spain. The medical reports were very enlightening. The clinic was absolutely consistent. But there was still more: in 2013 samples had been sent to the Carlos III Health Institute to analyze the possible infection by pathogens transmitted by ticks (Rickettsia, Ehrlichia, Anaplasma).
Those tests were negative at the time. As we have said, the Crimean-Congo hemorrhagic fever virus was not even contemplated. These samples were located and analyzed, this time to detect the virus by PCR and antibodies by serological techniques. They were positive. There was no doubt: it was the first case of Crimean-Congo hemorrhagic fever known in our country.
Will there be other cases that have gone unnoticed?
In addition to anticipating the appearance of the first case in Spain by three years, this study alerts us to the possibility that there have been more that have gone unnoticed, even earlier. In fact, this is the second retrospectively diagnosed case. There was another in 2018 that was diagnosed in 2019. The first positive ticks were detected in 2010, which could mean that this disease has been underdiagnosed in our country.
It is, therefore, the ninth case of Crimean-Congo hemorrhagic fever in Spain so far. Of these, three have been fatal (33%). It is a serious threat to public health that, until now, has produced sporadic cases, concentrated in the south-central area of the country. But that has been until now. How will it evolve? In Turkey they had not even heard of this disease until 2002 when sporadic cases began to occur that were gradually growing until today, which have 1 000 cases per year of which about 50 are fatal.
Hopefully this does not happen in Spain. For this, it is necessary to prepare, exercise effective surveillance and promote control of the disease, for which there is no vaccine or specific treatment.
It is also necessary to promote the knowledge among health personnel that this disease is present in our territory and they must be prepared to detect cases and treat them. In addition, they must know how to protect themselves, as they are at risk of acquiring it when treating affected patients.
This disease requires very strict biocontainment measures to reduce risk for those exposed to the virus. It is a pathogen that requires biocontainment level P4 laboratories to handle it. Spain currently lacks this type of laboratory , so it is difficult to investigate them in this country. It is very important that they are built. It is a question of sanitary sovereignty.
Miguel Ángel Jiménez Clavero, Virologist and Research Professor, National Institute for Agricultural and Food Research and Technology (INIA)
This article was originally published on The Conversation. Read the original.
