What is Chikungunya Fever?
Chikungunya fever is a viral disease that spreads through the bites of infected mosquitoes. Between February and October 2006, more than 1.25 million people in India and South Asia were infected with the chikungunya virus. Other large-scale outbreaks of chikungunya have occurred in eastern and central Africa and the countries of the Indian Ocean, including Gabon, Comoros, Mauritius, Madagascar, Mayotte, Maldives, Reunion (France) and the Seychelles. In September 2007, a chikungunyi outbreak was registered in northern Italy as a result of an imported case. The sharp increase in the incidence and expansion of the geogaphic prevalence of chikungunya in recent years demonstrates our vulnerability to emerging infectious diseases spread by insects, and underlines the importance of sustainable programs to combat them as an integral component of health security.
Causes of Chikungunya Fever
Chikungunya (CHIKV) is an arbovirus, that is, a virus transmitted from insects, a kind of alphavirus, transmitted by the bites of mosquitoes of the Kusak kind. It is possible to get infection in the Indian subcontinent, in Africa or Asia, and mosquito carriers have nowadays spread to Europe and North America. The first European outbreak of the disease chikungunya was in Italy. It is believed that the chikungunya virus (the word means “the one that twists”) is of African origin. Like the yellow fever virus, it circulates in nature between monkeys and mosquitoes of the Aedes subgenera Stegomyia, and in urban environments it is transferred from person to person by one of these mosquitoes, Aedes aegypti. The same cycle was established in Asia, where chikungunya spread quite widely. In rural areas of Africa, the incidence is sporadic, and epidemics occasionally occur in cities in Africa and Asia.
Pathogenesis during Chikungunya Fever
A chikungunya virus can be obtained by a human being bitten by a female mosquito, and the virus is transmitted from person to person. The main carriers are Aedes aegypti species and the white-spotted (A. albopictus) nipper (they also carry many other diseases). These mosquitoes can bite throughout the daytime; the peak of aggressiveness is early morning and late afternoon. Both species bite outdoors, but A. aegypti may also indoors. On average, the disease appears 4-8 days after being bitten by an infected mosquito, but the period can be from 2 to 12 days. In Africa, several other species of mosquitoes are also involved in the transmission of the Chikungunya fever, including species from the group A. furcifer-taylori and A. luteocephalus. There is evidence that some animals, including primates, may be carriers.
Symptoms of Chikungunya Fever
Chikungunya fever usually lasts from five to seven days and often causes severe and limiting pain functions in the joints, which sometimes last longer. The detailed clinical picture of the infection is more common in adults. The course can be very heavy.
After the incubation period (2-3 days), fever, severe arthralgia, chills, headache, photophobia, conjunctival hyperemia, loss of appetite, nausea and abdominal pain suddenly occur. Migratory polyarthritis affects mainly the small joints of the hands and feet, wrists and ankles. Large joints suffer less frequently. The rash appears from the beginning or after 2-3 days, during the decline of fever. The most intense rash occurs on the trunk and extremities, peeling is possible. Sometimes there are petechiae and nosebleeds, but in general, bleeding is uncharacteristic, even for children. Some patients have leukopenia.
In the blood, AcAT activity and C-reactive protein concentration are increased, and the number of platelets is slightly reduced. It may take several weeks to recover. In the elderly (especially in carriers of the HLA-B27 antigen), joint stiffness and arthralgia persist for a long time, articular effusion from time to time. Individual cases of ocular, neurological, cardiac complications and disorders of the gastrointestinal tract have been reported. The disease rarely leads to serious complications, but among older people the disease can be fatal. Often the disease occurs with minor symptoms and the infection may not be detected, and in the regions where the Dengue virus spreads, a wrong diagnosis is possible, since the symptoms of chikungunya and Dengue virus are the same.
Diagnostics of Chikungunya Fever
In the diagnosis of Chikungunya fever, various methods can be used. Serological tests, for example, immunosorbent assay using fixed enzymes (ELISA), are able to detect the presence of antibodies to the chikungunya virus IgM and IgG. The highest levels of the presence of IgM antibodies are reached 3-5 weeks after the end of the incubation period and lasts for 2 months. The virus can be isolated during the first days after it enters the blood. There are various methods of reverse transcriptase polymerase chain reaction (PCR-RT), but the sensitivity of these methods is different, and some of them are suitable for clinical diagnosis. PCR-RT products obtained from clinical samples are also used for genotyping a virus, which in turn makes it possible to compare virus samples from different geographic areas.
Chikungunya Fever Treatment
Chikungunya fever rarely takes a life-threatening form.
There is no special treatment for Chikungunya fever, but pain relievers and nonsteroidal anti-inflammatory medications can be used to relieve pain and against swelling. Important: Do not take aspirin!
Treatment of people affected by Chikungunya fever virus is carried out exclusively in a hospital. Patients are shown pathogenetic therapy, by means of which they achieve an improvement in the functions of the organs affected by the disease, normalization of metabolism, increase in nonspecific resistance and immune reactivity of the organism.
As mentioned above, in case of severe symptoms, the main efforts in the treatment of Chikungunya fever should be directed to reducing the temperature, reducing intoxication, getting rid of pain syndrome and other life-threatening manifestations.
The strengthening of the vascular wall is also important in the treatment of the disease, for which hemostatic treatment is prescribed to patients with Chikungunya fever.
With a strong arousal in patients, they are shown sedative drugs.
Chikungunya Fever Prevention
Developed a live vaccine against Chikungunya fever, which has not yet been tested. American scientists have developed a vaccine against chikungunya fever. The study was conducted by a group of specialists from the National Institute of Allergy and Infectious Diseases of the USA (National Institute of Allergy and Infectious Diseases, NIAID). During the study, employees of the Vaccine Research Center at NIAID found several structural proteins of the chikungunya virus, on the basis of which virus-like particles were created in the laboratory. By structure, these particles are similar to the pathogen fever, but can not cause infection. 15 days after the introduction of virus-like particles of rhesus monkeys, scientists infected the animals with the chikungunya virus. It was found that the injection of these particles contributed to the development of antibodies, which provided the animals with complete protection against infection. At the next stage of the study, serum with antibodies obtained from macaques was administered to mice with reduced immunity. After that, the rodents were injected with a lethal dose of chikungunya viruses. However, the introduction of serum prevented the development of fever in mice. Gary Nabel, director of the Vaccine Research Center, said that his colleagues intend to receive permission to conduct clinical trials of the developed vaccine. In addition, the researchers expressed the hope that the method of using virus-like particles could be used to create vaccines against diseases caused by other representatives of the alphavirus genus, in particular, western and eastern equine encephalitis, as well as o’nong-gong fever.
The preventive measures of Chikungunya fever consist in the prevention of mosquito bites, which occur mainly in the daytime, and the destruction of mosquito breeding sites. To prevent mosquito bites: – Wear clothing that covers as much skin as possible; – Spray open skin and clothing with mosquito repellents in accordance with the instructions contained in the annotation; – use mosquito nets to protect children, elderly and sick people, as well as those who rest during the daytime. The effectiveness of mosquito nets can be improved by treating them with WHO-recommended insecticides. – In the daytime, use mosquito coils and insecticide sprayers. Aedes mosquitoes that carry chikunguni virus breed in a variety of rainwater tanks that are usually located near residential buildings and workplaces, such as water storage tanks, potted pallets, pet water bowls, as well as abandoned cars. tires and food containers. To destroy mosquito breeding sites: – remove containers lying around the house; – Keep used containers upside down, and containers with water, including those that are indoors, empty every 3-4 days to prevent mosquitoes from reproducing or close them tightly to prevent mosquitoes from entering them.