What Do the Two First Autochthonous Cases of Crimea-Congo Haemorrhagic Fever in Spain Mean?

[This article has been written by Adelaida Sarukhan, PhD in Immunology scientific writter at ISGlobal, and Joaquim Gascon, Head of the International Health Service at Hospital Clínic and Director of the Chagas Initiative at ISGlobal, and published in Spanish in El País - Planeta Futuro]

Last year, the health authorities in Madrid confirmed the first two autochthonous cases of Crimea-Congo Haemorrhagic Fever in Spain, and in fact the first two ever in all Western Europe: one man that died and a nurse that recovered. These cases have just been published in the New England Journal of Medicine thereby officially declaring the disease autochthonous in Spain. To better understand the relevance of this, some context is necessary. 

These cases have just been published in the New England Journal of Medicine thereby officially declaring the disease autochthonous in Spain

In order to better understand the impact of the event, some context is needed. The disease was first described in Crimea in 1940 and four years later the virus was isolated in the Democratic Republic of Congo.  In humans, the disease causes a haemorrhagic fever that can be lethal in up to 40% of cases. The Crimea-Congo Haemorrhagic Fever (CCHF) is endemic in a wide geographic region that includes Eurasia and Africa. In Pakistan for example, it has caused 20 deaths since the beginning of 2016. 

Transmission

Livestock and other animals serve as a reservoir for the virus, since they get infected but do not show clinical signs of disease. It is transmitted by ticks (of the Hyalomma genus) that pick up the virus upon biting an infected animal. The virus is transmitted to humans mainly by the bite of an infected tick, but it can also occur by handling blood or tissues of infected animals. Human to human transmission through contact with bodily fluids is possible but rare, and is mostly limited to hospital settings and only when the necessary precautions are not taken. 

Symptoms

After a tick bite, the incubation period is one to three days in average. The first symptoms of the disease are quite general – fever, dizziness, muscle pain, headache and light sensitivity. After some days, the symptoms can worsen going from nausea and abdominal pain to severe liver, kidney and lung damage. Death occurs generally after two weeks of symptom onset.  

Treatment

There is an experimental vaccine for cattle (used on a small scale in Eastern Europe). However, there is no approved vaccine or treatments for the disease in humans, although the antiviral drug ribavirin has been used with certain success. The only preventive measures consist in avoiding tick bites by using repellent and light-coloured clothing that permits to detect them, as well as using gloves and protective clothing when handling blood or tissues of animals in endemic areas. 

Although it is likely an exceptional case, it highlights the urgent need to investigate the presence and distribution of virus-infected ticks across the country

Now, the case in Spain draws attention for two reasons. To begin with, it is the first case of autochthonous transmission of the virus in Western Europe (the most western countries to have confirmed cases up to now were Serbia and Croatia). Second, because it normally occurs in people that are in close contact with animals, such as farmers, cattle breeders or veterinarians. Although it is likely an exceptional case, it highlights the urgent need to investigate the presence and distribution of virus-infected ticks across the country. A study performed in Spain in 2011 had already warned of the CCHF virus in some ticks recovered from deer in the region of Caceres, but it is still not known whether this is also the case for regions of the Mediterranean or of Southern Europe.

As with any other emerging infectious disease, the case calls for a heightened state of alert, but there is no reason for alarm

The possibility that migratory birds introduce infected ticks also needs to be further investigated. Obviously, these kind of epidemiological studies require time and money, but are essential to better assess the risk of having other cases like this one, and to establish appropriate protocols of sanitary surveillance. 

The conclusion is that, as with any other emerging infectious disease, the case calls for a heightened state of alert, but there is no reason for alarm. 

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