What is Chikungunya?

Chikungunya fever is an acute infectious disease caused by Chikungunya virus (CHIKV), transmitted by Aedes mosquito, and characterized by fever, rash, and joint pain. The chikungunya epidemic was first confirmed in Tanzania in 1952, and the virus was isolated in 1956. The disease is mainly prevalent in Africa and Southeast Asia, and has caused a large-scale epidemic in the Indian Ocean in recent years.

Basic Information

English name: chikungunya fever
Visiting department: Infectious Diseases
Common causes: Chikungunya virus (CHIKV), transmitted by Aedes mosquito

Common symptoms: Chills, fever, headache, nausea, vomiting, loss of appetite, enlarged lymph nodes, etc.
Contagious: Have
way for spreading: Aedes aegypti and Aedes albopictus

Chikungunya fever transmission pathway

Aedes aegypti and Aedes albopictus are the main vectors of transmission of the disease. It is transmitted mainly by the bite of the infected Aedes mosquito. It may be transmitted through aerosols in the laboratory, and no direct human-to-human transmission has been reported.

Population susceptibility: People are generally susceptible to CHIKV, and infection can be manifested as a dominant infection or a recessive infection.

Chikungunya fever clinical manifestations

The incubation period for this disease is 2 to 12 days, usually 3 to 7 days.

Acute phase

(1) Fever patients often have sudden onset, chills, fever, body temperature up to 39 ° C, accompanied by headache, nausea, vomiting, decreased appetite, and enlarged lymph nodes. Generally, fever can be reduced within 1 to 7 days, and some patients have mild fever (bimodal fever) after about 3 days, which returns to normal after 3 to 5 days. Some patients may have conjunctival congestion and mild photophobia of conjunctivitis.

(2) 80% of patients with rash develop rashes on the trunk, extremities, palms, and soles of the limbs 2 to 5 days after the onset of skin rash, pimples, or purpura. The skin between the rashes is mostly normal, and some patients have itching sense. It fades after a few days and may be accompanied by slight desquamation.

(3) Joint pain and fever At the same time, multiple joints and spine appear pain, joint swelling, and may be accompanied by systemic myalgia. Joint pain is mostly migratory, which increases with exercise and is more severe in the morning. The condition develops rapidly, often with joint function loss and inability to move within minutes or hours. It mainly involves small joints, such as the hand, wrist, ankle, and toe joints, and may also involve large joints such as knees and shoulders. The severe pain caused by compression of the wrist joint is a characteristic of this disease. Joint effusion is rare. X-ray examination is normal.

(4) Meningoencephalitis, liver damage, myocarditis, and skin and mucous membrane bleeding can occur in a very small number of other patients.

2. Recovery period

After the acute phase, joint pain and stiffness can be fully recovered in most patients. Some patients have persistent joint pain and stiffness for weeks to months, or even more than 3 years. Individual patients have sequelae such as impaired joint function.

Chikungunya fever check

General inspection

(1) The white blood cell count of the routine blood test is mostly normal, and the total number of white blood cells, lymphocytes, and platelets are slightly reduced in a few patients.

(2) Serum ALT, AST, and creatine kinase (CK) increased in some patients during biochemical examination .

(3) Cerebrospinal fluid examination Cerebrospinal fluid examination of patients with meningoencephalitis is consistent with changes in viral injury.

2. Serological examination

(1) Serum-specific IgM antibodies are detected by ELISA, immunochromatography and other methods. The results of capture method to detect IgM antibodies are more reliable. Generally, IgM antibodies appear on the first day after onset, and most patients are positive on the fifth day.

(2) Serum-specific IgG antibodies were detected by ELISA, immunofluorescent antibody assay (IFA), and immunochromatographic methods. Generally, IgG antibodies appear on the 2nd day after the onset, and most patients are positive on the 5th day.

3. Etiological examination

(1) Nucleic acid detection is detected by nucleic acid amplification methods such as RT-PCR and Real-timePCR. Viral nucleic acid can be detected in the serum of most patients within 4 days after the onset of disease.

(2) Virus isolation . Serum specimens from patients within 2 days of onset were collected, and the virus was isolated with sensitive cells such as Vero, C6 / 36, BHK-21 and HeLa.

Chikungunya fever diagnosis

Diagnose based on:

Epidemiological information

Living in an endemic area of Chikungunya or having a history of travel within the epidemic area within 12 days and a history of mosquito bites within 12 days before onset.

2. Clinical manifestations

Acute onset, with fever as the first symptom, a rash over 2 to 5 days, and severe joint pain.

3. Laboratory inspection

(1) Positive for serum-specific IgM antibodies;

(2) The serum specific IgG antibody titer in the recovery phase is more than 4 times higher than that in the acute phase;

(3) Detection of chikungunya virus RNA from patient specimens;

(4) Chikungunya virus was isolated from patient specimens.

Diagnostic criteria: Suspected diagnosis: those with the above epidemiological history and clinical manifestations; those without epidemiological history, but with the typical clinical manifestations described above. Confirm the diagnosis: Anyone who has any of the laboratory tests in the diagnostic basis on the basis of the suspected diagnosis.

Chikungunya fever differential diagnosis

Dengue fever

Chikungunya fever and dengue fever are transmitted through the same media, and the endemic areas are basically the same. The clinical manifestations are also similar, and it is difficult to distinguish between dengue fever and dengue fever. Chikungunya fever has a shorter fever period, joint pain is more pronounced and lasts longer, and bleeding tendency is lighter. Identification depends on laboratory-specific testing.

2. O'nyong-nyong and other alpha virus infections

O'nyong-nyong virus, Mayaro virus and other alpha virus infections have similar clinical manifestations to chikungunya fever, and are not easy to distinguish based on clinical manifestations and general laboratory tests. Differential diagnosis is required through specific tests. Because of the antigenicity of these viruses, the results of serological tests need careful analysis. Nucleic acid detection and virus isolation are the main methods to identify these viral infections.

3. Infectious erythema

Caused by parvovirus B19, erythema of the palate appears first, with pale mouth circumference, and maculopapular rash on the trunk and limbs 2 to 5 days later. Joint damage is manifested as polyarticular periarthritis, which mostly occurs in the proximal knuckles and palm joints and can invade the wrist, knee and ankle joints. Parvovirus B19-specific antibodies and nucleic acids tested positive.

4. Other

This disease also needs to be distinguished from diseases such as influenza, measles, rubella, infectious mononucleosis, rheumatic fever, and bacterial arthritis.

Chikungunya fever treatment

There is no specific drug treatment for this disease, mainly symptomatic treatment.

General treatment

Fever period should be bed rest, should not go to the ground too early to prevent the disease from getting worse. Take anti-mosquito isolation measures.

Symptomatic treatment

(1) Cooling For patients with high fever, physical cooling should be adopted first. Patients with obvious bleeding symptoms should avoid alcohol rubbing bath. Non-steroidal anti-inflammatory drugs can be used, avoiding the use of aspirin drugs.

(2) Analgesics can be used for those with severe joint pain.

(3) The main points of treatment for meningoencephalitis are prevention and treatment of cerebral edema. Cranial pressure can be reduced by using drugs such as mannitol and furosemide.

(4) Rehabilitation treatment Joint pain or mobility disorders can be rehabilitated.

Chikungunya fever prevention

The prevention of chikungunya fever mainly adopts the following measures.

Control the source of infection

Try to treat locally to reduce the chance of transmission. Patients should be protected against mosquitoes during viremia. The isolation period was 5 days after the onset of illness. Suspected and confirmed cases should be reported in a timely manner.

2. Cut off the transmission route

There should be mosquito nets, screens, screens and other anti-mosquito equipment in the ward. Eliminate mosquitoes and clear mosquito breeding grounds.

3. Protect vulnerable people

No vaccine is currently available. Mainly take personal anti-mosquito measures.