Chikungunya

The infection is caused by Chikungunya single-stranded RNA virus (CHIKV), an alphavirus of the family Togaviridae. The vectors of its transmission are mainly mosquitoes of the genus Aedes. Characterized by their black bodies with white stripes and the fact that they are active both day and night, they are two species also involved in the spread of other dangerous diseases such as yellow fever and dengue. Aedes aegypti is the main vector and is usually found in tropical and sub-tropical regions. Aedes albopictus is what we call the "tiger mosquito" and is found in more temperate areas of Europe, Asia, and Africa.

The transmission cycle of the disease revolves around the mosquito bite. Having come into contact with the virus by feeding on the blood of an infected animal (in nature, the main reservoir is typically, but not exclusively, the monkey, while during epidemics it is the human being), it carries the virus for life and transmits it during subsequent meals. Transmission of the virus from the infected person is most likely in the first 2-6 days of the acute phase. This most typically occurs with human-mosquito passage, but human-to-human transmission is also possible with direct contact with infected blood or by vertical transmission from mother to fetus during pregnancy.

The Chikungunya virus has been identified in more than 60 countries across Asia, Africa, Europe and the Americas. Italy holds a grisly record in the spread of the disease: the first autochthonous outbreak (i.e., with cases of the disease not contracted during travel) in Europe was found in 2007 in Emilia-Romagna and resulted in more than 200 cases between July and September of that year. The global distribution of Chikungunya shows that the virus is expanding at an accelerated rate due to multiple factors, such as climate change and the subsequent spread of the vector mosquito, urbanization, or interocontinental travel, which can influence the development of disease outbreaks even in areas that had never experienced it.

Source: CDC

The incubation period of Chikungunya is generally 3 to 7 days (which can range from 1 to 12 days, however) after the sting. Usually the onset of the disease is characterized by the onset of fever (above 39 °C) accompanied by severe debilitating joint pain, while other symptoms may include headache, muscle pain, arthritis, nausea and maculopapular rash (similar to measles) .Most patients usually recover completely after a week, but in some cases joint pain may persist for several months or even years.Rarer symptoms include uveitis, retinitis, myocarditis, hepatitis, nephritis (the inflammation of the kidney), hemorrhage, meningoencephalitis, myelitis, Guillain-Barré syndrome, and cranial nerve palsy. More serious complications are not common, but possible particularly in people at risk, such as infants exposed during childbirth, the elderly (over 65 years), and people with conditions such as hypertension, diabetes, or heart disease.

Suspicion for Chikungunya may arise from the patient's clinical examination, with observation of manifested symptoms, or from medical history (e.g., recent travel to endemic area).
Generally, virus detection is based on the search for viral nucleic acid or specific immunoglobulin and neutralizing antibodies. Serological tests, such as enzyme-linked immunosorbent assays (ELISAs), can confirm the presence of anti-chikungunya IgM and IgG antibodies. IgM antibody levels are highest 3 to 5 weeks after disease onset and persist for about 2 months. The virus can be isolated from blood during the first few days of infection. Various reverse transcriptase-polymerase chain reaction (RT - PCR) methods are available, but with variable sensitivity. RT-PCR products from clinical samples can also be used for virus genotyping, allowing comparisons with virus samples from various geographic sources.

There is no specific antiviral treatment for chikungunya and no commercial vaccine. Treatment is directed primarily at relieving symptoms, including joint pain, and on supporting vital functions.The CDC suggests paying attention to personal hydration and using acetaminophen to reduce fever and pain-it recommends never taking aspirin or other nonsteroidal anti-inflammatory drugs until the diagnosis for dengue has been ruled out.

Prevention for Chikungunya transmission begins with proper behavioral prophylaxis, especially during the day, a time when mosquitoes are most active.

1. Use an effective mosquito repellent.
   The Centers for Disease Control and Prevention (CDC) recommends repellents with the following active ingredients: DEET (>25%); Picaridin; IR3535; Eucalyptus Lemon Oil (OLE); Para-menthane-diol; 2- undecanone.
2. Cover yourself
   Use clothing that covers your legs and arms, preferably light colored.
3. Check the environment around you
   Standing water is a perfect habitat for mosquitoes to breed. Make sure there is no stagnant water in: discarded tires or industrial containers, swimming pools, storm drains, and saucers. To reduce the risk ti transmission, systematic control through pest control campaigns against the Aedes population turns out to be a key intervention.