Chikungunya virus (CHIKV) is a flavivirus virus, a family of viruses that also includes dengue virus, zika virus, yellow fever, etc. Diseases transmitted by these viruses are arboviruses, so called because these viruses are arboviruses (short for ar thropod- bo rn virus es), that is to say, they are transmitted by arthropods, sucking insects blood like mosquitoes.
CHIKV was identified for the first time during an outbreak in 1952/1953 on the Makondé Plateau in Tanzania. Its name comes from a word of makondé language that means “curved”, because of the leaning forward attitude that some people adopt. CHIKV may have been responsible for fever epidemics with joint pain well before this date when it was identified.
After Africa, and Southeast Asia, it colonized the Indian Ocean in 2004, with in particular an exceptional epidemic in Réunion in 2005/2006 (300 000 people affected), then the American continent (including including the Caribbean), Asia and Oceania. CHIKV is now present in Southern Europe since 2007, when a localized outbreak occurred in northeastern Italy. Since other outbreaks have been recorded in France and Croatia.
It is now considered that all countries with a warm season or climate may be subject to epidemics.
In September 2015, it is estimated that the mosquito Aedes albopictus is implanted in 22 French departments of metropolitan France which are put under a regional surveillance device strengthened. With a drop in imported cases, 30 cases in 2015 were imported against more than 400 in 2014. On October 21, 2014, France confirmed 4 cases of infection with chikungunya contracted locally in Montpellier (France).
The epidemic continues in Martinique and Guyana, and the virus circulates in Guadeloupe.
The islands of the Pacific Ocean are also concerned and cases of chikungunya appeared in 2015 in the Cook Islands and Marshall Islands.
What are the causes of the disease, the mode of transmission of the virus?
CHIKV is transmitted to humans through the bite of mosquitoes of the genus Aedes, which are also the agents responsible for the transmission of dengue, zika and yellow fever. Two mosquitoes of the Aedesfamily are able to transmit the Zika virus, Aedes aegypti in tropical or subtropical zone, and Aedes albopictus (the “tiger” mosquito) in more temperate zones.
The mosquito (only the female stings) contracts the virus by pricking an infected person or animal and can then transmit this virus by pricking another person. These Aedes are essentially active at the beginning and end of the day.
The CHIKV virus, when injected by the saliva of the mosquito in a man or a woman, diffuses in the blood and the ganglia, then reaches certain organs, mainly the nervous system and the joints.
The person infected with chikungunya is not directly contagious to another human being. On the other hand, if she is bitten again by a mosquito of the Aedes genus , she transmits the virus, and this mosquito can then transmit the disease to another person.
The transmission of the chikungunya virus by blood transfusion or organ transplant would be possible, hence the precautionary measures taken to rule out the donation of blood among people with the disease. The virus can also be transmitted from the mother to her child during pregnancy or childbirth.
What are the symptoms ? When to consult
Long considered benign, the disease has attracted most attention since the outbreak of 2006 in Reunion, with the appearance of serious forms.
Classically CHIKV infection occurs between 1 and 12 days after the bite by the infected mosquito, usually between the 4th and 7th day, with:
– the sudden onset of high fever (above 38.5 ° C ),
– significant muscular and articular pains concerning essentially the extremities (wrists, ankles, fingers), and concerning less often the knees, the shoulders, or the hips.
– a rash on the trunk and limbs with red spots or slightly raised spots.
– bleeding from the gums or nose can also be observed.
– swelling of certain nodes,
– conjunctivitis (inflammation of the eyes)
The infection can also go completely unnoticed, but more rarely than in the case of zika.
It is important to see a doctor if there is:
– Sudden fever, associated or not with headaches, muscle and joint pain, skin rash, people living in an epidemic area or who have not returned for less than 12 years days must consult.
– The notion of travel or stay in an epidemic area if they are associated with fatigue or persistent pain.
During the consultation, the doctor looks for symptoms of chikungunya, and also other diseases, especially those that can be transmitted by the same mosquitoes as dengue or zika.
How is the diagnosis made?
During acute CHIKV infection, there is a decrease in lymphocytes (white blood cells) and platelets in the blood and an increase in transaminases (liver enzymes).
The specific diagnosis of CHIKV is done on a blood test by:
– the assay of antibodies in the blood, present from the 4th or 5th day and persisting for several years.
– the detection of the virus itself in the blood is rarely requested.
What is the evolution of the disease? Its complications?
Infection with CHIKV results in long-lasting immunity, ie the same person will only be able to do it once the disease.
The spontaneous course of the disease is most often favorable, but it can progress to a chronic form, with for several months’ prolonged fatigue and / or the persistence of joint pain (in 20% of cases) for months or years. sometimes very embarrassing in everyday life.
The involvement of other organs is possible:
– Neurological disorders such as Guillain-Barré syndrome (involvement of the peripheral nerves responsible for paralysis, muscle weakness or sensory disturbances with eg tingling in the arms and legs). Some cases of meningoencephalitis were observed during the outbreak in Reunion.
– Eye damage: spontaneously healing conjunctivitis, loss of vision.
– complications in the kidney, liver or heart are exceptional.
It seems that the pain related to CHIKV focus mainly on organs or areas already previously weakened by a pathology, trauma, and anterior intervention.
What are the treatments ?
There is currently no specific treatment for chikungunya and there are no drugs that can cure it.
The treatment addresses the symptoms of the disease, with analgesics, such as paracetamol;
Caution : Nonsteroidal anti-inflammatory drugs and aspirin are contraindicated during the acute phase of infection, the possible coexistence with the dengue virus exposes to the risk of bleeding. People suffering from severe forms are hospitalized for specific care.
The existence of chronic forms of chikungunya has led doctors confronted with these new forms of diseases that were poorly known to reflect on the methods of care at the initiative of the University Hospital of Fort de France. This led to the development of recommendations that now constitute the benchmark for international treatment. In the
.epidemic zones, teams bringing together doctors in charge of rehabilitation or pain, infectiologists, neurologists, rheumatologists, psychiatrists, etc. manage persons with chronic forms of incapacitating disease by combining antalgics and / or non-steroidal anti-inflammatory drugs with rheumatological, neurological and functional re-education.
In all countries where CHIKV has been conducted, people have used traditional methods of care that may or may not include the use of plants. Research programs are underway on traditional uses of medicinal plants. While waiting for the results, it is disadvised to treat oneself. It is better to seek advice from your doctor, the plants having like drugs their own efficiency and their contraindications.