Chikungunya fever is a viral disease that is spread to humans by the bites of infected Aedes aegypti mosquitoes. This article discusses the transmission, clinical manifestations and treatment guiding principles by National Vector Borne Disease Control Programme (NVBDCP).

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Chikungunya

Chikungunya virus (CHIKV) is a member of the family togaviridae, genus Alphavirus. In the Swahili language, chikungunya means that which contorts or bends up or illness of the bended walker. This refers to the deformed (or stooped) posture of individuals suffering from significant joint pain (arthritis), the most prevalent symptom of the condition. It is a disabling virus that is not lethal.

A cycle of human-mosquito-human transmission maintains the chikungunya virus in the human population. Chikungunya fever outbreaks exhibit seasonal and cyclical patterns. In the post-monsoon season, when the vector density is extremely high and transmission is amplified, outbreaks are most probable. Humans act as the reservoir for the chikungunya virus during epidemics.

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Transmission

The bite of an infected mosquito deposits the chikungunya virus (CHIKV) in the subcutaneous tissue of humans, resulting in viremia. Viral replication is signalled by the production of inflammatory cytokines during a feverish reaction. Perivascular lymphocytic cuffing and biopsies of a cutaneous rash reveal the extravasation of erythrocytes from capillaries. Experimental research on similar flaviviruses has shown that the virus reproducing in the synovial fluid is infectious.

The endosteum and periosteum of afflicted bones stimulate complement-mediated immune responses. Arthritis with complicated aetiology In the latter stages, the involvement of synovial joint spaces results in a full-blown case of arthritis. No synovial lymphocytosis, bone, or cartilage degeneration is seen. Other alpha viruses' neurovirulence and neuroinvasiveness (neurotropism) have been demonstrated. CHIKV is also capable of causing CNS symptoms such as encephalitis, encephalomyelitis, and optic neuritis.

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Diagnosis

Probable or suspected case: A patient only if they fulfil the prerequisites.
Confirmed (definitive) case: a patient meets both the clinical and laboratory criteria.

Clinical criteria: 

Acute onset of fever and severe arthralgia/arthritis, with or without rash, and residence or departure from an epidemic region 15 days previous to the beginning of symptoms.

Laboratory criteria:

At least one of the following tests done in the acute phase of illness
Direct evidence -Virus isolation / Presence of viral RNA by RT-PCR
Indirect evidence - Presence of virus-specific IgM antibodies in a single serum sample collected in the acute or convalescent stage. Four-fold increase in IgG values in samples collected at least three weeks apart.

Differential diagnosis
Fever with or without arthralgia is a frequent symptom of a number of different disorders. Among the disorders that may be evaluated in the differential diagnosis are the following:

1. Dengue fever: Extreme low back discomfort accompanied by purpura or active bleeding may indicate dengue illness. Laboratory diagnosis confirmation is feasible.
2. Reactive arthritis: Any kind of arthritis that develops within six months after a febrile illness of the gastrointestinal or genitourinary tract (caused by infectious agents) is labelled reactive acute inflammatory arthritis. Enthesitis is characterised by the involvement of collagenous structures that enter into bone, such as tendons and ligaments. Oral mucosal ulcers are seen
3. Serum sickness illness: Polyarthritis may be connected with a serum sickness-like reaction brought on by vaccination, medicine, or other viral diseases.
4. Rickettsial disease: It can present with fever, rash and joint pains. Confirm by serology.
5. Rheumatic fever: More prevalent in youngsters and characterised by transient (migratory) polyarthritis affecting mostly the major joints. The modified Jones criteria should serve as the diagnostic standard. In addition to an elevated ASO titre and a history of recurrent sore throat are generally observed.
6. Malaria: Patients may manifest with high fevers and musculoskeletal discomfort. Periodicity of fever and altered consciousness/convulsions should suggest a malaria diagnosis.
7. Leptospirosis: In a person with a history of skin contact with polluted water, severe myalgia confined to the leg muscles with conjunctival congestion/or subconjunctival haemorrhage with or without oliguria or jaundice would imply Leptospirosis.

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Clinical manifestation 

Incubation period:
The CHIK virus produces an acute febrile disease with a 3-7 day incubation period (maybe 2- 12 days). Viraemia may last up to 5 days after symptoms appear. Chikungunya fever is characterised by arthralgia and fever.

Clinical features:
Chikungunya's clinical appearance is split into three stages. Chikungunya symptoms usually appear suddenly, with a high temperature, single or many joint aches, skin rashes, headache, and myalgia. Chikungunya generally manifests itself in three stages.

Those are listed below:

1. Acute phase: Less than 3 weeks
2. Sub-acute phase : > 3 weeks to 3 months
3. Chronic phase : > 3 months

Clinical manifestations might be mild, moderate, or severe, and the majority of symptoms resolve within three weeks after start. Some of the symptoms may last for three months or more. Typically, 10 to 15% of patients who present with severe chikungunya advance to the subacute or chronic phases.

Common symptoms observed are as follows: 

• Fever
• Arthralgia/Arthritis
• Backache
• Headache
• Skin rash/Itching

Rare in adults but seen sometimes in children

• Photophobia
• Retro-orbital pain
• Vomiting
• Diarrhea
• Meningeal syndrome
• Acute encephalopathy

The course of illness:
The majority of patients' symptoms and indicators are self-limiting. Some indications and symptoms develop in the subacute or chronic phases.

1. Arthralgia
2. Myalgia
3. Arthritis
4. Persistent joint stiffness
5. Restricted joint movement
6. Painful joint movement
7. Enthesopathy
8. Tendinitis
9. Skin pigmentation
10. Skin rash

Clinical classification of severity of chikungunya:
The severity of chikungunya is divided into three categories based on clinical presentation; however, this category may change over time throughout the disease.
Mild-

• Low-grade fever
• Mild Arthralgia
• Mild focal Myalgia
• General weakness
• Skin rash/itching

Moderate-

1. Low to high-grade persistent fever
2. Moderate joint pain
3. Generalised myalgia
4. Hypotension
5. Mild bleeding
6. Retro-orbital pain
7. Oliguria

Severe-

• Persistent high-grade fever
• Severe Joint pain
• Persistent vomiting / diarrhoea
• Altered sensorium
• Bleeding (GI bleeding due to the use of Analgesics)
• Shock due to persistent vomiting and diarrhoea

High-risk group
Patients who have chikungunya infection plus one of the following illnesses may be termed high-risk group patients because they are more prone to have severe manifestations and bad outcomes.
Co-morbid condition:

1. Hypertension
2. Diabetic
3. CAD/CVD
4. Geriatric age
5. Pregnancy
6. COPD
7. Hypothyroid

Fever: The fever ranges from mild to high grade and generally lasts 24 to 48 hours. It has a sudden onset and normally responds to antipyretics.
Arthralgia/Arthritis: Arthralgias are polyarticular and mainly impact the peripheral joints. The joint discomfort is worst in the morning and improves with little physical exercise. In other people, the discomfort may subside for 2-3 days before reappearing in a saddleback pattern. It is often polyarticular and symmetrical, affecting mostly small joints of the hands and feet. Ankles, wrists, and tiny hand joints are the most severely afflicted. In larger joints, such as the knee and shoulder pain is also possible.

With some prior damage or degeneration, there is a propensity for earlier and more substantial involvement of joints. According to accounts, fever rash usually appears within five days after the commencement of the condition. While a tiny percentage of individuals may have diarrhoea towards the end of the week. The majority of the Scarring (exfoliation of the skin in children and residual arthralgia in adults) occurs most often between the sixth and tenth day of infection.

Backache: One of the most prevalent chikungunya symptoms is a characteristic posture. Back pain may be significant in the early stages of the illness.

Headache: One of the early warning signs could last for the first week of illness.

Rash: Up to 50% of individuals get a transient maculopapular rash. In almost 10% of instances, the maculopapular eruption lasts longer than 2 days. Photosensitive hyperpigmentation and nasal blotchy erythema are more commonly seen. In around 5% of patients, exfoliative dermatitis affecting the face and limbs was seen. Children with epidermolysis bullosa have been seen. Except in situations where the photosensitive hyperpigmentation lingered, the majority of skin lesions fully healed. Vesiculbullous eruptions and intertriginous aphthous-like ulcers were seen in individuals. A few people experienced purpuras and fewer had angiomatous lesions.

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Neurological manifestations

Meanigeal syndromes and encephalopathy are uncommon chikungunya symptoms. But sometimes, toes that point up and neck stiffness may be observed. Similar to this, encephalopathy in extremely rare situations may cause unconsciousness to manifest. These are often temporary.

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Occular manifestations

There have been reports of neuroretinitis and uveitis in one or both eyes. Additionally seen are anterior uveitis, optic neuritis, retrobulbar neuritis, and dendritic lesions. In general, the visual prognosis is favourable.

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Chikungunya in elderly

Because of their already weakened physical defences, which increase the risk of aggravating any existing medical condition, older persons are more vulnerable to chikungunya. Elderly people recover more slowly from chikungunya infections, which may be severe and can include oedema. In senior individuals, chikungunya may result in neurological issues including dementia, paralysis, and renal abnormalities. In line with this, children are more susceptible to the devastating effects of chikungunya than adults since they are less able to articulate specific symptoms and it may take longer to detect the illness in them. In comparison to individuals in other age groups, elderly patients with co-morbidities may have higher problems and psychological side effects.

Sequelae:
Although chikungunya is a self-limiting illness, it may have serious consequences. Joint pain has been shown to fully disappear in 90% of cases. However, some have either of the following:

• Episodic stiffness and pain.
• Persistent stiffness without pain.
• Persistent painful restriction of joint movements.

Up to 53% of those with musculoskeletal involvement also experienced enthesopathy and tendinitis of the tendon Achilles. The effects of Chikungunya fever are worse in older patients (>45 years), those with significant first joint pain symptoms, and patients who already have osteoarthritis. Chikungunya infection also has neurological, emotional, and dermatological consequences that are discussed.

Mortality:
Chikungunya is often not lethal, and dying from it is quite uncommon. Due to concurrent illnesses, chikungunya infections may increase both morbidity and death. From 2006 to 2009, there were no reports of chikungunya-related deaths in India. 

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Clinical management

As per National Vector Borne Disease Control Programme (NVBDCP), the guiding principles of clinical management are as below:

1. Management during acute and sub-acute phases of the illness and management during chronic phase or sequelae:

1. There are no antiviral drugs against CHKV
2. Most of the signs and symptoms are self-limiting.
3. Treatment for chikungunya is purely symptomatic - supportive care and rest and nutrition.
4. Analgesics, antipyretics and fluid supplementation are important aspects of managing this infection.
5. Supportive or Palliative Medical Care With Anti-inflammatories
6. Supportive care with rest is indicated during the acute joint symptoms.
7. Movement and mild exercise tend to improve stiffness and morning arthralgia, but heavy exercise may exacerbate rheumatic symptoms.
8. There Is no vaccine currently available.

2. Disabling peripheral arthritis/ arthropathy refractory to NSAID:

• Short-term corticosteroid may be used.
• Long-term anti-inflammatory therapy.
• Physiotherapy
• Chloroquine phosphate

3. Management of chikungunya with the high-risk group:

Proper management of Co-morbid conditions and co-infection.
Acute stage: Clinical Management of CF during the acute stage can be in ambulatory settings. Hospitalisation is rarely indicated.

(a) Domiciliary (Home care)

1. Adequate rest or activity as tolerated.
2. Paracetamol 500 mg TDS/QID ( dose not to exceed 3 Gm24 hours).
3. Antacids like PPI/H2 blockers to counter gastritis.
4. Antihistaminics, if required in consultation with doctors.
5. Tepid water sponging for high fever.
6. Ensure adequate intake of water orally to maintain a urine output of at least more than a litre per day.
7. Cold compresses involved painful joints. Avoid hot fomentation in acute stages as it can worsen the joint symptom.
8. Physiotherapy in form of mild exercises in recovering patients.
9. Avoid self-medication, particularly antibiotics, steroids, and other painkillers especially overdosing.
10. Avoid Aspirin.

(b) Clinic based

At the OPD level:  The differential diagnosis of dengue fever, malaria, and other pertinent disorders must be ruled out in all instances of fever by a medical officer via a history-taking process, clinical examination, and fundamental laboratory tests. If chikungunya fever is clinically confirmed (probable case)

Paracetamol can be used to treat the patient's symptoms. If the pain is intractable then NSAIDs like ibuprofen (400 mg three times daily), naproxen (250 mg twice daily), diclofenac (50 mg twice daily) and other NSAIDs. Paracetamol needs to be continued. To minimise gastric intolerance, H2 blockers ranitidine 150mg bd or proton pump inhibitor like Omeprazole 20 mg od may be used. There is no definite role of steroids in the management of CF including arthralgia.

An NSAID should typically be used for two weeks before patients are moved to a different NSAID if it proves unsuccessful. For individuals with contraindications, such as known liver disease or increased aminotransferases, acetaminophen and NSAIDs should both be taken in the lowest dosage and for the shortest time required and avoided.

Aspirin and other NSAIDs should not be used in patients who may have dengue virus infection until dengue has been ruled out or until 14 days after the onset of symptoms, with the patient afebrile for at least 48 hours and no warning signs for severe dengue (severe abdominal pain, persistent vomiting, mucosal bleeding, pleural effusion or ascites, lethargy, enlarged liver, and increased hematocrit with decrease in platelet count).

This is significant given the possibility of Reye syndrome in children using salicylates and the danger of bleeding issues linked to dengue infection, which may be exacerbated by aspirin or other NSAIDs. Even if chikungunya infection is established, acute dengue illness must be ruled out since the two viruses may coinfect people.

Only paracetamol or mefenamic acid is safe to use during pregnancy; avoid NSAIDS throughout the third trimester. According to the degree of dehydration, the patient should be rehydrated.

Criteria for referral to a secondary centre:

1. If the person has hemodynamic instability (frequent syncopal attacks, hypotension with a systolic BP less than 100 mmHg or a pulse pressure less than 30 mmHg),
2. Oliguria (urine output less than 500 ml in 24 hours),
3. Altered sensorium or bleeding manifestations.
4. It may be advisable to refer persons above sixty years and infants (below one year of age0. 
5. Severe incapacitating arthritis not responding to paracetamol or NSAIDS for more than 15 days.

Guiding principles for managing chronic pain (Chronic chik arthritis)

1. Since an immunologic aetiology is suspected in chronic cases, a short course of steroids may be useful.
2. Non-weight bearing exercises may be suggested.
3. Contractures and deformities with physiotherapy/surgery
4. NSAIDS
5. Short course of steroid ( In case of refractory to NSAID after 2-3 weeks))
6. HCQS ( During sub-acute stage)
7. Physiotherapy
8. Surgery

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Prevention 

For the prevention of chikungunya fever, there is no specific therapy and no vaccination. The sole method for preventing and managing epidemics is vector control. When a patient is afflicted, mosquitoes may carry the virus and transfer it to others. By reducing the vector density via community involvement and implementing the necessary control measures in the hospital environment, it is crucial to stop this transmission reduce the spread of infection reduce the number of insects

Reduce the amount of time that the vector and patient are in touch (Aedes mosquitoes mostly bite early in the day and late at night) warning the home members about risks. Lower larval habitats in and around homes; eliminate standing water from any clutter in the home and the peri-domestic regions. This will help to reduce the vector population. Various types of residential / home containers containing Aedes mosquito breeding water. Reduce the amount of interaction between the vector and the patient by using insecticide sprays, wire-mesh/nets on doors and windows, and wearing long sleeves to protect your extremities, especially in bright colours.

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This is the next article of our monsoon series. To read the earlier articles of the series, click here:Managing dengue fever: What you should know; Malaria in monsoon: Recent updates ;Leptospirosis: A commonly misdiagnosed disease; Know cholera: Diagnosis and treatment approach

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Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

About the author of this article: Dr Monish Raut is a practising super specialist from New Delhi.