Mosquito-borne diseases. What do Polish mosquitoes infect with?

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Mosquitoes are one of the biggest killers among animals. Reason? They are the carriers of many dangerous diseases. The tiger mosquito, which comes from Asia, is particularly notorious. It turns out, however, that Polish mosquitoes can also transmit pathogens. What can we get infected with? What should you be careful about, especially on vacation? In an interview with Medonet, Dr. Jarosław Pacoń from the University of Life Sciences in Wrocław explains.

1. Mosquitoes are considered the most deadly among animals – they can transmit pathogens of many dangerous diseases
2. One of the best known is malaria. But it’s also viral diseases like yellow fever, dengue fever, meningitis, Rift valley fever, Japanese encephalitis
3. In Poland, the only threat from mosquitoes is heartworm disease – a parasitic disease caused by tissue nematodes of the genus Dirofilaria
4. More interesting information can be found on the Onet homepage.

Why are mosquitoes dangerous to humans and animals?

Mosquitoes are said to be one of the most dangerous animals in the world. However, you have to be aware that the mosquito itself is not a killer – it alone will not kill us. – There have been no such cases in humans. However, there are cases where mosquitoes were the direct perpetrators of animal deaths, emphasizes Dr. Jarosław Pacoń. Such events were recorded in the southern US states in periods when rainfall appeared after a prolonged drought.

– Under such conditions, mosquito eggs, larvae and pupae began to appear, waiting for favorable conditions. After two or three weeks, it was noticed that cattle began to fall on the pastures, the scientist says. – It turned out that there were so many mosquitoes that by stabbing animals and sucking their blood, they made them violently anemia. In addition, there were extensive allergic and inflammatory conditions caused by the saliva of insects.

The animals began to die. – These were not mass falls, but several dozen individuals in the herd were killed – says Jarosław Pacoń. They were mostly young animals.

So why are mosquitoes, though so small, the world’s deadliest animal? The answer is known: because they can transmit pathogens of many serious diseases. And it’s not just mosquitoes from tropical regions of the world.

What can mosquitoes in Poland infect?

Also “our” Polish mosquitoes are a spreader of diseases. – Fortunately, not fatal – emphasizes Dr. Pacoń. There are several diseases spread by Polish mosquitoes and they are dangerous mainly to our animals, including dogs. However, we can also become infected with one of them.

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This is heartworm disease, an infectious disease caused by a parasite called a tissue nematode from the genus Dirofilaria. First of all, it occurs in dogs – it is located under the skin and in internal organs, e.g. in males in the spermatic cord, in bitches – in the area of ​​the uterus, but in fact Dirofilarias can appear in any internal organ.

Human heartworm can also be infected. – Such a case was recorded for the first time in 2009 in Łódź. This nematode has lodged itself in the subcutaneous tissue – says Dr. Jarosław Pacoń, adding: – A dozen or so years ago it was not here in Poland. This parasite was imported from southern Europe.

The second species of parasite transmitted by “our” mosquitoes is much more dangerous for dogs (but not for us). It’s a heartworm. This parasite develops in the right ventricle and atrium, and in the pulmonary artery. – In Poland, these are rare cases, but they do occur – emphasizes Dr. Pacoń. Like Dirofilaria, this nematode was also imported from southern Europe. – If we also take our dog with us on vacation to Greece, Italy or Spain, there is a risk that after being bitten by a local mosquito, the animal may become infected with this parasite – warns the scientist and reminds: – This nematode does not infect your dog. The dog is not a threat to us here.

Jarosław Pacoń mentions one more threat posed by “our” mosquitoes – a viral disease dangerous for rabbits – myxomatosis. – In the 60’s – 70’s it was a fatal disease, nowadays vaccinations are used – he says.

“There are still species of mosquitoes in Poland that can transmit malaria”

The most famous mosquito-borne disease is undoubtedly malaria. We mainly associate it as a tropical disease. – However, it is worth remembering that until 1968 we had a native malaria, in Polish, “malaria”. It occurred in the vicinity of the Vistula Spit and in some regions on the coast – reminds Dr. Pacoń. – At the turn of the 40s and 50s, there were several thousand cases of infections, but thanks to an effective preventive action, in 1968, the WHO stated that Poland is a completely malaria-free country.

– Let’s remember, however, that there are still species of mosquitoes in Poland that can transmit malaria – warns the scientist, adding: – They do not transmit it, because this disease does not exist in our country.

Currently, malaria is only imported to us. – Until 2011, the average number of cases was 40 to 60 per year. Currently, there are more and more of them, although the pandemic has somewhat stopped this trend. In 2018-2019, up to 100 cases of imported malaria were recorded annually. That’s a lot. And these are just stated cases. In addition, there are many unidentified cases – people are infected but have no symptoms, the researcher notes.

Malaria occurs almost everywhere in Africa, it is recorded from the southern border of the Sahara to South Africa, including Madagascar. – Therefore, if we are going on a trip to Africa, we must remember to protect ourselves and not bring such a passenger (malaria is a parasitic disease). The more so because then our lives can be decided by hours. Several million people die of malaria each year, most of them in Africa.

How to protect yourself against malaria? Remember before vacationing in the tropics!

Unfortunately, the malaria vaccine is 30-50% effective, only works for a few months and is used only in the most vulnerable areas, admits Dr. Pacoń. So what can we do? – So it’s best to find a doctor who specializes in tropical diseases and who will prescribe us special medications a few weeks before departure. They are taken before departure, during and for several weeks after returning – explains and warns: – The problem may be the situation when we use the last minute offer. For example, we only have a week to leave and a lot of things to do. If, in addition, we hear that he is not vaccinating against malaria, we go peacefully, and then it turns out that we brought an unwanted passenger with us.

Malaria is one thing, heartworm is another, but there are also viral diseases that mosquitoes can infect us with. This includes yellow fever, dengue fever, meningitis (known as West Nile disease), Rift Valley fever, Japanese encephalitis. – So far, no viruses causing these diseases have been identified in Poland. However, the animals were diagnosed with antibodies, which means that they had contact with such a pathogen, but did not get sick – says Dr. Jarosław Pacoń.

The scientist reminds that the West Nile virus has been located in the Czech Republic. – Of course, this is not proof that this virus normally occurs in the Czech Republic, that it already exists there – the disease is not there – he explains. – It has happened that these viruses have been identified in migratory birds arriving from Africa – they do not get sick themselves. I would also like to emphasize that they are not a threat to us.

You may be interested in:

1. Seven mosquito-borne diseases – there is nothing to fear!
2. Why do mosquitoes usually fly around the head and ears? Experts explain
3. How can I prevent mosquito bites from itching? Doctor’s advice