Chikungunya is a mosquito-borne viral disease, very similar to dengue. The mosquitoes which spread it are Aedes aegypti and Aedes albopictus. These mosquitoes acquire the virus when they feed on an infected person. The virus spreads in the system of the mosquito and reaches its salivary glands. Soon after, when the mosquito feeds on a person, it infects him. The infection lasts for 2 to 12 days.
The word ‘chikungunya’ is believed to have been derived from a description in the Makonde language, meaning “that which bends up”, of the contorted posture of people affected with the severe joint pain and arthritic symptoms associated with this disease. The disease was first described by Marion Robinson and W.H.R. Lumsden in 1955, following an outbreak in 1952 on the Makonde Plateau, along the border between Mozambique and Tanganyika (the mainland part of modern-day Tanzania).
According to the initial 1955 report about the epidemiology of the disease, the term ‘chikungunya’ is derived from the Makonde root verb kungunyala, meaning to dry up or become contorted. In concurrent research, Robinson glossed the Makonde term more specifically as “that which bends up”. Subsequent authors apparently overlooked the references to the Makonde language and assumed the term to have been derived from Swahili, the lingua franca of the region. The erroneous attribution to Swahili has been repeated in numerous print sources. Many erroneous spellings of the name of the disease are also in common use.
Since its discovery in Tanganyika, Africa, in 1952, chikungunya virus outbreaks have occurred occasionally in Africa, South Asia, and Southeast Asia, but recent outbreaks have spread the disease over a wider range.
The first recorded outbreak of this disease may have been in 1779. This is in agreement with the molecular genetics evidence that suggests it evolved around the year 1700
The geographical distribution of chikungunya fever has changed in recent years. Initially found in Africa, there were at first few cases reported. In 2005, this strain underwent mutation and spread across the islands of the Indian Ocean. By 2006-2007, the outbreak had reached India and other parts of Asia and Southeast Asia, as well as parts of the Pacific region.
In 2013, there was first notification of locally acquired chikungunya fever in the Caribbean and since that time there have been a huge number of cases in the Caribbean and the Americas. More than 1.2 million cases have been reported in 44 countries or territories in the Americas since.
There have been no locally acquired cases in the UK, as the temperature is not warm enough for this mosquito to breed; however, cases acquired in travellers have increased since the spread of the virus to the Caribbean and Americas. In 2014, there were 295 reported cases in England, Wales and Northern Ireland, with 88% having been acquired in the Caribbean or South America. Prior to this geographical spread, there were few cases and these had mostly been acquired in India or Southeast Asia. There were a few locally acquired cases in the South of France in 2014.
Regions affected are those with warm tropical or subtropical climates. Risk is highest in the rainy season when numbers of mosquitoes are at their greatest. The infection is not transmitted directly between humans but only through the bite of a mosquito which has bitten another infected individual. Vertical transmission from mother to child has been reported, and neonates have been reported to contract the disease from infected mothers, with severe consequences.
It affects all age groups but more than 50% of those with severe disease are over the age of 65 years – of which a third will die. Usually those with the severe form of the disease and complications have underlying morbidity. Severe illness also occurs in children.
Incidentally, both Dengue and Chikungunya are caused by Aedes aegypti and Aedes albopictus mosquitoes, two species that are playing havoc in the country. It is transmitted from one person to another with the bite of the female specie of the mosquito. These mosquitoes are known to typically bite during the daylight hours. During the daylight hours, the risk of getting bitten is the highest at two points of time, early morning and late afternoon. Though, typically these mosquitoes are known to bite outdoors, aedes aegypti can also bite indoors.
The signs and symptoms typically start with one or more of the following – chills, fever, vomiting, nausea, headache, joint pain, etc. There is also a high possibility that the fever may touch 100 to 104 degree Celsius. The attack is sudden, sometimes accompanied with rashes. However, in children, the infection causes no symptoms at all.
Some of the major physical symptoms of Chikungunya are as follows:
Redness in the eye: This typically means that one is likely to suffer from conjunctivitis and face difficulty in looking towards the light.
Headache: Frequent and severe headache is a common symptom of Chikungunya that may continue for days together at a stretch.
Severe joint and body pain: This type of pain is frequent and keeps increasing as the days pass. Sometimes, the joints also get swelled up due to severe pain.
Appearance of rashes usually on limbs and trunks: Symptoms of Chikungunya are also known to cause rashes on entire body which keep coming back frequently.
Bleeding: The person suffering from this disease, is at a high risk of suffering from bleeding. Haemorrhage may occur at times too.
Some of the clinical symptoms of chikungunya seen in children are as follows:
- Retro – orbital pain,
- Diarrhoea, and
- Meningeal syndrome.
Some complications of chikungunya include:
- Neurological imbalances
- Myocarditis or inflammation of the heart muscle
- Ocular disease or eye disease (uveitis, retinitis)
- Hepatitis caused by liver damage
- Acute renal disease when kidneys get affected
- Severe bullous lesions
- Neurological diseases, such as meningoencephalitis, Guillain-Barré syndrome, myelitis, or cranial nerve palsies
Diagnosis and test
Currently, there is no preventive vaccine available against Chikungunya. But looking at the situation and the potential threat for severe morbidity, there is a need for prompt, proper and accurate diagnosis and treatment. Some of the available tests include – Viral culture, serologic and polymerase chain reaction (PCR)-based tests, etc.
Serum or plasma Test: Usually the laboratory diagnosis is accomplished by examining the patient’s serum or plasma to detect the virus, the viral nucleic acid or virus-specific immunoglobulin (Ig) along with neutralizing antibodies. The viral RNA of Chikungunya virus can also be identified in serum, during the initial first eight days of illness.
Viral Culture: Viral Culture can also detect the virus in the first three days of the illness.
Treatment and medications
There is no medicine or vaccination available for treating Chikungunya Virus. But some of the precautionary measures include:-
- Taking plenty of rest.
- Drinking ample amount of fluids to prevent dehydration.
- Taking medicines such as- Acetaminophen or paracetamol for fever and pain.
- The only method to counter the virus is to avoid being stung by mosquitoes, especially when traveling in areas where the disease is in a great amount.
- If one is in a situation of high risk of complications, such as- being pregnant or suffering from any serious medical problems, he/she must try to avoid visiting the places with an outbreak of Chikungunya.
The usual treatment for the severe form of chikungunya consists of:
- Providing Intravenous (IV) fluid and electrolyte replacement
- Monitoring blood pressure
- Blood transfusion to replace blood loss, if any
In order to prevent mosquito bites:-
- One must wear long or full sleeved shirts and pants before going out. If possible, apply permethrin, a type of insecticide to repel mosquitoes.
- A mosquito repugnant must be applied on the exposed parts of the skin, preferably one that contains DEET ((N, N-diethyl-3-methylbenzamide), picaridin, IR3535 (3-[N-acetyl-N-butyl]-aminopropionic acid ethyl ester), oil of lemon eucalyptus or paramenthane-diol (PMD).These are some of the suggested ointments as they are highly effectiveness and stay for long.
- One should make sure that the windows and doors are duly locked. Also, it is suggested that one must use insecticide treated mosquito nets, not only at night but most importantly during the day time as it’s the time of the day when the chances of one being stung by an infected mosquito are the highest.