A dangerous virus transmitted by mosquitoes. How is qigungunia manifested? [NEW PANDEMIC?]

The Chikungunya virus and the disease it causes (called in Poland qigongunia) is known to a fairly small group of experts. The inquisitive will also find it on the WHO website. The organization classified it to the group of diseases with epidemic and even pandemic potential. Although the infection is usually mild, it poses a great threat to public health due to the epidemics that have occurred in recent years in areas where the virus was previously unknown. Why did the World Health Organization scrutinize this virus, explains Prof. dr hab. n. med. Marta Wróblewska, specialist in the field of medical microbiology and epidemiology.

1. Chikungunya virus is transmitted by mosquitoes – Egyptian or tiger mosquitoes, species found all over the world in tropical and subtropical regions. The tiger mosquito is also found in countries with a temperate climate
2. The virus has already reached Europe, the most cases of infections were recorded in 2014 – 1461. In Poland, in 2019, two cases were recorded
3. Although we are infected with the Chikungunya virus by mosquito bites, transmission from a pregnant woman to a fetus or newborn (so-called vertical) is also possible
4. The main symptoms of infection are: very severe joint pain, fever above 39 degrees C, headache and muscle pain, joint swelling, general weakness and conjunctivitis
5. Work on chikungunia vaccines is ongoing. A vaccine based on virus-like particles is particularly promising
6. More current information can be found on the Onet homepage.

Monika Zieleniewska, Medonet: Only specialists dealing with, for example, tropical medicine have heard about the Chikungunya virus in our country. What do we actually know about him?

Prof. Marta Wróblewska: The Chikungunya virus (abbreviated CHIKV) has been known since the 50s. In the years 1952-1953 it caused an epidemic in Tanzania, infections also occurred in neighboring Mozambique. Outbreaks followed shortly thereafter in Asia – in 1960, Thailand, Pakistan, and then elsewhere on the continent. Until recently, infections only occurred in Africa and Asia (India and Southeast Asia), but the virus has spread to other geographic regions since the beginning of the 30st century. It causes large epidemics in areas with mosquitoes that carry it. Even 80 to XNUMX percent are infected. local people.

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How do we get infected?

The virus belongs to arboviruses, i.e. viruses transmitted by arthropods (mosquitoes and ticks). We become infected by a mosquito bite, which previously fed on the blood of an infected person. The virus is transmitted by the Egyptian mosquito (Ae. Aegypti) or the tiger mosquito (Ae. Albopictus). The Egyptian mosquito comes from Africa, while the tiger mosquito comes from Asia. Currently, both species are found worldwide in tropical and subtropical regions, and the tiger mosquito also in countries with a temperate climate. The risk of infection of a mosquito, especially its female, is greatest during the viremia phase (when viruses are present in the human blood), which occurs in the first week after the onset of disease symptoms. Studies have shown that on the second day after infection, the virus is present in the mosquito’s salivary glands and can be passed on to another person. It was also found that the maximum mosquito infectivity is on the 6th – 7th day after infection. The female’s infectivity may persist until the end of her life (about a month).

You said that the XNUMXst century brought new epidemics of qigungunia also in areas where they had not occurred before. Where?

As in the 2004th century, epidemics of this disease took place in Africa and the islands in the Indian Ocean at the beginning of the 2006st century. An epidemic was recorded in Kenya in 500–2016, followed by the disease on neighboring islands in the Indian Ocean. In total, approx. 1700 thousand cases. In 80, almost 2018 cases were recorded in Kenya, while 2019% fell ill during the epidemic in Somalia. the population of the city of Mandera. In 270-5, the epidemic broke out in Sudan (less than 2020 cases and XNUMX deaths), and in XNUMX in Chad. At that time, epidemics also occurred in India, Southeast Asia and the Middle East.

In the years 2005 – 2006 in India and on the islands of the Indian Ocean approximately 1,4 million people fell ill. On the island of Réunion, almost a third of the population was infected. Indian travelers brought the virus to countries in Southeast Asia, and from there to Europe, the US and Taiwan. In 2011, there was an epidemic in Yemen that resulted in nearly 100 deaths. In 2016, about 2,5 thousand people fell ill in the capital of India – New Delhi. people, and throughout the country about 65 thousand. A few months later in 2017, an epidemic struck neighboring Pakistan.

In the years 2010 – 2013, cases caused by the Chikungunya virus were observed in the USA, but it was only a few to several dozen cases annually in people returning from epidemic areas (the so-called imported cases). In 2013, the first locally spreading infections with this virus were confirmed in the Caribbean. In 2014 and 2015, the epidemic hit the US and South America. In 2014, almost 700 jobs were recorded. suspicious cases (including approx. 300 thousand in Colombia) and almost 37,5 thousand. confirmed infections. In 2016, almost 350 people were re-registered in South America. suspicious cases and almost 150 thousand. confirmed; mainly in Brazil, Bolivia and Colombia. By the end of 2017, there were nearly 2,6 million cases of Chikungunya disease in the Americas.

The virus has already reached Europe when?

In 2007, 217 cases of infections were reported in Italy as a result of transmission of the virus by the Aedes albopictus tiger mosquito present in the country. This means that CHIKV can spread throughout Europe. In 2013, 72 cases were found on our continent – mainly in France, Great Britain and Germany. The highest number was in 2014, as many as 1461. In the following year, the number of cases dropped to 624, and in 2016 to 492. In 2017, the European Center for Disease Control (ECDC) registered 548 cases (84% confirmed) of infections in 10 countries. Local transmission of the virus has reappeared in France and Italy. According to ECDC data from 2018, cases were reported in 14 countries, a total of 160 cases. All of them were imported from other regions of the world (56% from Asia and 33% from Africa). In 2014-2018, Chikungunya infections occurred in 19 countries, most of them in France, Great Britain, Spain, Germany and Belgium. During this period, infections were also recorded in the Czech Republic every year. Two cases were recorded in Poland in 2019.

According to WHO data, the disease has already been recorded in over 60 countries around the world. In recent years, most cases have occurred in South America, the Caribbean and Asia. This year (until May 5, 2022), almost 50,5 thousand jobs were recorded in the world. Chikungunya virus infections (including seven deaths), of which over 48,6 thous. in Brazil. The high epidemic potential of this virus is evidenced by the fact that since the last report published on April 6, 2022, i.e. within a month, the number of infections has increased by over 38.

So virus-carrying mosquitoes occupy areas with increasingly colder climates?

It is transmitted by mosquitoes of the genus Aedes, most often the Egyptian mosquito – Aedes aegypti, which is also a vector of other dangerous viruses, e.g. yellow fever, dengue fever or the Zika virus. Initially, the mosquito was found only in Africa, but now it is found in tropical or subtropical regions around the world. In turn, the tiger mosquito is also found in countries with a temperate climate. The reservoir of the virus is humans and other primates. Man is contagious just before the onset of disease symptoms and for two to six days of illness. An infected person has a high viral load of viral load for five to six days (maximum 10). This favors the infection of a large number of mosquitoes living in a given area and the transmission of the virus to other people.

So we only get infected after being bitten by a mosquito that carries the virus?

Unfortunately not. In addition to infection, acquired through the bites of infected mosquitoes, it is also possible to transmit the virus vertically from a pregnant woman to a fetus or newborn – during pregnancy or during childbirth. In the USA in 2014-2015, vertical infection of the fetus during pregnancy occurred in 1,3%. cases, and during childbirth in 25 percent. Most infected newborns are born healthy, but symptoms may appear in the first week of life.

Infection in newborns can manifest as encephalitis or other neurological diseases, hemorrhagic symptoms, and involvement of the heart muscle. The risk of the baby being infected is greatest if the mother becomes infected at the end of pregnancy and is viremic during delivery. The impact of the virus on the health of perinatally infected newborns is not yet known. There have been reports of miscarriages in women infected with Chikungunya virus during the first trimester of pregnancy. However, the virus has not yet been detected in human milk. Transmission by organ transplantation or blood or blood products transfusion has not been confirmed, although cases of infection of laboratory workers who come into contact with the blood of patients infected with this virus have been documented.

How long does it take from a mosquito bite to the first symptoms to appear?

Chikungunya has a breeding time of one to 12 days, but is usually three days to a week. Symptoms occur in most people who are infected; in about 70 – 95 percent

I know the disease owes its name to one of the symptoms.

The most characteristic symptom is very severe joint pain, which affects approx. 80 percent. patients. The name of the virus in the language of the Makonde tribe of Tanzania, where the first epidemic of this disease was recorded, translated into English is “that which bends up”. It refers to the bent position of patients due to severe pain. In many people (approx. 30-65%) joint pain may persist for several months or even several years.

What about other symptoms?

You can mention a fever above 39 degrees Celsius, headaches and muscle pains, joint swelling, general weakness and conjunctivitis. A macular-papular skin rash may appear on the trunk and extremities. Very rarely, the infection can be fatal, but it applies rather in people with comorbidities (e.g. hypertension, diabetes, cardiovascular diseases).

How long have we been sick?

The disease lasts from 7 to 10 days, up to two weeks, and may resemble a Zika virus or dengue infection. In some regions of the world, these diseases occur in a given area at the same time. All three viruses are transmitted by the same species of mosquitoes, so laboratory diagnosis is required to confirm the diagnosis. The disease is usually mild. Complications in the form of myocarditis, inflammation of the eyeball, hepatitis, acute kidney failure, blistering skin lesions, as well as neurological complications (meningitis and encephalitis, spinal cord inflammation, cranial nerve paralysis or Guillain-Barré syndrome) occur rarely. But there is also good news – immunity after being infected with Chikungunya virus probably lasts for life.

Do we have any medications for qigungunia?

There are currently no antiviral drugs to inhibit viral replication. Treatment is symptomatic. Patients are given antipyretics and analgesics. It is recommended to rest and hydrate the body. In more severe cases, anti-inflammatory drugs such as corticosteroids are used.

Returning to the European backyard, should we be afraid of a new disease?

According to an assessment by ECDC, the conditions for the spread of vectors carrying Chikungunya virus in continental Europe are currently not favorable, so the risk of infection is negligible. As I have already mentioned, for several years this virus has been present in various regions of the world in countries with a temperate climate, also in Europe, beyond the areas of its current occurrence. It turned out that other mosquitoes, including the tiger mosquito – Aedes albopictus, can also transmit it due to the mutations that have taken place in this virus.

Unfortunately, this poses a threat to Europe, as the tiger mosquito can survive and reproduce in a temperate climate, especially in the Mediterranean, but also in cooler places. Currently Ae. albopictus is already present in many European countries. It has been observed, among others at our neighbors – in Germany, the Czech Republic and Slovakia. In 2007, outbreaks of Chikungunya virus infections spreading locally in Italy with the involvement of the Ae mosquito were found. albopictus, in people who have not recently reported their travels to other regions of the world (so-called native cases). However, it should be emphasized that the virus is transmitted by mosquitoes, and not from person to person (with the exception of perinatal infections of the fetus or newborn), so to prevent infection, you should carefully protect yourself from mosquito bites.

So if the climate doesn’t warm, are we safe?

Mosquitoes like a warm climate, so their habitat is expanding with global warming. The temperature in the mountains is also increasing, which means that the area of ​​occurrence of carriers (the so-called vectors) of many infectious diseases (e.g. malaria, some viral diseases) is increasing. Unfortunately, it has been shown that people in the upland and mountain areas of South America and Africa are now at greater risk of arthropod-borne diseases than in the 90s. According to ECDC data, by 2030 the area with conditions for the multiplication of the tiger mosquito in Europe will significantly increase, also to the north to cooler areas, such as the Baltic countries or the south of Sweden. It can be assumed that if global warming is stopped, then the area of ​​mosquito-borne viruses will not increase as it does today.

Probably the best weapon against infection would be a vaccine. Has the research started?

There is currently no registered vaccine against this virus. But such a prophylaxis option will be possible after completing the research of preparations based on various technologies that are under development. In early March this year, it was announced that the Phase 3 single-dose live attenuated (live virus) vaccine (VLA1553) clinical trials had been successfully completed. After a month, 98,9 percent. vaccinated study participants had a protective level of neutralizing antibodies, and after 6 months – 96,3 percent. Similar results were obtained in August last year. Moreover, the vaccine was also found to be effective in older adults (over the age of 65) who have had as good a protective antibody response as younger participants. By mid-year, the pharmaceutical company that developed the vaccine plans to apply to the FDA (Food and Drug Administration in the United States) for its registration. Other vaccines are under development (at various stages) – inactivated, recombinant and others. A vaccine based on virus-like particles (VLP) is very promising. In clinical trials, up to 98 percent. participants developed antibodies neutralizing the Chikungunya virus within 7 days after a single dose, and the immune response was maintained after one year of follow-up.

How can we protect ourselves now, before an effective vaccine is on the market?

Avoid exposure to mosquitoes by wearing appropriate clothing and using repellants and mosquito nets. In the area where Ae mosquitoes occur. aegypti and Ae. albopictus, measures are needed to reduce their population in the human environment, mainly through the use of insecticides. There are attempts to use biological methods consisting in introducing a population of sterile males in a given area. Outbreaks tend to occur during the rainy season, but can also occur in droughts if there are ponds of water in the vicinity of human habitats that allow mosquitoes to breed (including buckets and pots). Therefore, people at risk of severe Chikungunya infection, suffering from hypertension, diabetes or heart disease, should verify their travel plans to regions where there are currently cases or even epidemics of this disease.

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