At the end of October, the Chief Sanitary Inspector confirmed a new case of suspected infection with West Nile virus in a person returning from Egypt. He emphasized that although the virus was the same, the place of its acquisition was completely different than in the case from a few days before. This refers to information from Chief Sanitary Inspector that everything indicated that infection with this virus had occurred in Poland and there was a high probability that the patient was infected by a mosquito that had previously drunk the blood of a sick bird.

'We have been expecting for some time that diseases (...) such as West Nile virus or other viruses transmitted by mosquitoes will be more and more common in our environment', says Professor Maciej Grzybek, a biologist and parasitologist from the National Centre for Tropical Medicine and the Institute of Maritime and Tropical Medicine of the Medical University of Gdańsk.

He adds that this is caused by climate change, i.e. as the climate warms and temperatures increase, diseases that we once called tropical will start appearing in our geographical zone. 'This is a huge threat that we must be prepared for', he says.

Grzybek adds that the case proves that this virus can appear and has appeared in the Polish population of blood-sucking insects, primarily mosquitoes. 'We recently had reports that the virus (...) was detected in birds in the vicinity of Warsaw. This is not surprising, because birds migrate to warm countries, where they are bitten by mosquitoes and other blood-sucking insects and (...) bring various types of pathogens to Poland', he says.

When asked whether a mosquito that bites a person infected with West Nile fever can transmit the disease to another person, he replies that 'hypothetically it is possible, but it happens very rarely'. He says that the virus is mainly transmitted by mosquitoes that bite infected birds. And it is mosquitoes that pose a real threat to humans.

He adds that in Poland there are species of mosquitoes capable of transmitting a very wide range of pathogens that can threaten the health of humans and animals, e.g. malaria, West Nile virus, Dengue virus, or chikungunya virus (a tropical viral disease occurring mainly in southern Asia and eastern Africa, similar to dengue fever, transmitted by several species of mosquitoes).

'I am not saying that every mosquito in our kitchen or in our garage is infected, because this requires biomonitoring programmes, i.e. analysing and searching for pathogens and vectors of diseases in our environment', he says. 'Until the government decides on appropriate analyses and biomotoring programs, we cannot make informed, responsible decisions. Real financial outlays are needed for national programmes that will tell us what these pathogens are and where they occur in our country', Professor Grzybek adds.

Referring to the patient who returned from Egypt, the professor says that there are many 'imported infections, infections with various pathogens' every year. He adds that the changes we are observing, i.e. traveller activity, transport availability, population migration, trade - will cause us to have more and more imported cases of various types of tropical diseases.

Grzybek explains that this primarily concerns viruses transmitted by blood-sucking insects, including mosquitoes - West Nile fever, dengue, chikungunya. The expert also draws attention to ticks, including migratory ticks - Hyaloma marginatum - a species that can carry Crimean-Congo haemorrhagic fever. Its presence in Poland, he adds, was confirmed by Professor Anna Bajer from the University of Warsaw in the citizen science project 'National Tick-Picking'.

According to Grzybek, the health care system must be prepared to act and respond to a real threat. He emphasises that, first of all, it is necessary to strengthen laboratory diagnosticians through training, substantive preparation on how to conduct successful, effective diagnostics of these infections; to prepare and support the State Sanitary Inspectorate so that it has the ability to track and detect potential outbreaks of a given disease. It is also necessary, he adds, to prepare doctors, infectious disease specialists and primary care physicians, as well as infectious disease departments so that they are ready to treat an increased number of patients who may bring such diseases to the country.

When asked about the current preparedness, he says that 'we have not done our homework from the SARS-CoV-2 pandemic, which clearly showed that Poland was not prepared to diagnose a pathogen that caused mass infections'. He adds that at the beginning of the pandemic we had 'only one diagnostic laboratory that was able to diagnose SARS-CoV-2 virus infection'. Therefore, in the case of tropical diseases, as he points out, it is necessary to 'strengthen, as soon as possible: sanitary inspection, laboratory diagnostics, specialized centres that already conduct such research - e.g. the Institute of Maritime and Tropical Medicine in Gdynia, or the National Institute of Hygiene'.

He adds that we need to prepare the services for appropriate action in the 'One Health' partnership; combine the forces of scientists, diagnosticians, doctors, but also the government, in order to make informed, responsible decisions and take care of health.

He continues that steps should be taken as soon as possible, because pathogens are already appearing in our geographical zone.

Grzybek also says that it is very important to inform and educate the public, because it is impossible to travel and avoid being stung by a blood-sucking insect - and one sting can cause the development of a disease.

'We appeal to patients to prepare for the trip before leaving. Dear patient, if you are travelling to an area where tropical diseases, malaria, West Nile virus, dengue fever occur, seek medical advice, take repellents with you, ask a doctor for chemoprophylaxis to protect yourself from infection, from the malaria parasite. Use mosquito nets and electric fumigators, i.e. electrical devices that emit substances mosquito repellents', says Professor Grzybek. (PAP)

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