Mosquito and tick bites can spread several different diseases, and the ranges of these insects are shifting as the climate changes. One tick-borne disease is Crimean-Congo haemorrhagic fever (CCHF), which is now affecting people in Europe as well as Africa and Asia. For now, the European cases seem to have been confined to Spain, Russia, Turkey, and the Balkan region.
In 2010, surveillance efforts revealed that there were ticks in Spain that were infected with Nairovirus, a virus in the Bunyaviridae family that causes CCHF. In 2016, doctors there began to identify the first cases of CCHF in people, which were outlined in a 2017 report in the New England Journal of Medicine. The first patient that fell ill succumbed to the disease while the second survived. Eight other cases have been reported in Spain since then.
While tick bites often spread CCHF, it can also be transmitted through direct contact with infected bodily fluids from animals or humans. As such, veterinarians, health care workers, and agricultural workers are at risk.
Right now there are not any treatments or vaccines that are made specifically for CCHF. The virus typically incubates for three to seven days. About 80 percent of cases or more seem to be mild, or even asymptomatic, according to the European Centre for Disease Prevention and Control. If the disease does cause symptoms, they can include fever, fatigue, headache, abdominal pain, diarrhea, or vomiting. In the worst cases, hemorrhaghic symptoms emerge.
It's estimated that about 10,000 to 15,000 cases of CCHF occur around the world every year, and about 500 of those cases are fatal. Around 30 percent of people who are hospitalized for the disease end up dying from it. The World Health Organization has warned that the disease poses a major threat to human health, noting the high case fatality rate among those who are hospitalized.
Other diseases are on the move too. Dengue fever is caused by dengue virus, which is spread by a type of mosquito called the Asian tiger mosquito (Aedes albopictus) that has migrated to Southern Europe from the tropics.
Doctors are also about to announce a case of dengue fever that occurred in a British woman who went to Nice, France for vacation and contracted the illness there. Other people who stayed where she was in France had also fallen ill with the same symptoms, but she did not seek care until returning home to the UK. About 30 cases of dengue fever were confirmed in the south of France in 2022, according to Dr. Owain Donnelly of the Hospital for Tropical Diseases in London.
After her symptoms, including muscle pain, fever, headache, and a widespread rash were evaluated, the Rare Imported Pathogens Laboratory (RIPL) in the UK confirmed that it was dengue fever. The patient recovered on her own.
While it's estimated that about 75 percent of dengue fever cases are asymptomatic, anywhere from one to five percent of people who are infected will get a severe illness and potentially, dengue hemorrhagic fever.
Sources: New England Journal of Medicine, Horizon: The EU Research & Innovation Magazine, US Centers for Disease Control and Prevention
