Chikungunya

Has three genotypes, which behave as a single seotype.

Circulates in forested regions of sub-Saharan Africa.

Like or RNA viruses, it is constantly evolving, allowing the virus to spread and cause disease, including the emergence of novel lineages.

With climate change, global travel and the ability to infect the Aedes albopictus  mosquito, it is likely the infection that it will move north.

A mosquito borne alpha virus found in tropical and subtropical regions of the world that has caused outbreaks in more 100 countries with disease characterized by fever and disabling joint symptoms.

Chikungunya viruses primarily transmitted to humans through bites from infected mosquitoes and humans are the primary host during outbreaks.

The transmission cycle continues with mosquitoes become infected after biting a viremic human and then transmit the virus to other humans.

Less commonly chikungunya virus can be transmitted in utero, during labor and delivery, via percutaneous, needle stick or laboratory exposure.

Vector Aedes aegypti mosquito.

Incubation time is between two and six days, resulting in a febrile illness characterized by arthralgias, polyarthritis, and rashes.

Transmission cycles involving nonhuman primate hosts and arboreal mosquito vectors.

Has caused large epidemics affecting millions of people across Africa, Asia, South Africa, the Caribbean and the Americas.

In addition to causing disease and residence, living in risk areas, infections may occur in travelers to these areas.

Global travel, sequence variations that improve viral infectivity, dissemination, and transmission and climate related warming that enhancs factors related to transmission have led to increases in cases and geographic areas affected.

Infection usually provides long lasting immunity.

Infection follows a short incubation period, fever, hedache, maculopapular rash, joint and muscle pain.

Most patient with chikungunya virus infection (65-85%) have symptoms usually sudden onset of fever, polyarthralgia after an incubation period of 3 to 7 days.

The acute febrile illness lasted of seven days.

Joint pain is present in more than 90% of cases and is often severe and disabling.

Other frequent symptoms include rash, headache, myalgia, nausea, vomiting, and non-purulent conjunctivitis.

Joint symptoms are usually bilateral and symmetrical and involves hands and feet.

Complications occurring less than 1% of cases and include myocarditis, ocular disease, hepatitis, and neurologic events.

Risk for hospitalization include those younger than six months and older than 65 years and those with comorbidities.

Death is rare, 0.1–0.5% occurring primarily in young infants and older individuals with comorbidities.

More than half of patients have persistent or recurrent symptoms, especially joint pain, stiffness, and fatigue.

Endemic in East Africa to Southeast Asia.

Up to 35 million chikungunya virus infections are estimated to occur annually worldwide.

Severe arthralgia is hallmark of Chikungunya fever.

Between 30-50% of patients can experience debilitating arthritis and fatigue for years afterward.

Typically has a rapid onset febrile disease, associated with intense myalgias, headache, fever, rash, arthralgias, inflammatory arthritis, malaise,headache, conjunctivitis, or other systemic symptoms.

Up to 60% of infected patients develop chronic arthritis, which can persist for months or years.

Complications include cardiomyopathies, autoimmunity, and neurologic disease.

Fever fellows a mean incubation period of three days and the highest temperature is usually higher than 39°C.

In contrast to other arboviral diseases the majority of infected have symptoms with less than 15% of patients being asymptomatic.

An infection caused by the Chikungunya virus.

Manifests with sudden onset of fever usually lasting two to seven days, along with a joint pains typically lasting weeks, months and sometimes years.

The mortality rate is a little less than 1 in 1000.

Elderly most likely to die from Chikungunya.

The virus is passed to humans by two species of mosquito of the genus Aedes: A. albopictus and A. aegypti.

Animal reservoirs of the virus include: monkeys, birds, cattle, and rodents.

During periods of epidemics humans are the reservoir of the virus.

Chikungunya is mostly present in the developing world.

In dengue only humans and primates are hosts.

The best means of prevention is overall mosquito control, and avoidance infected mosquito bites.

The immunologic response is characterized by the appearance of IgM anybodies  within 2 to 5 days following infection and IgG after several weeks.

No specific treatment.

Incubation period ranges from two to twelve days.

Incubation period typically three to seven days, and between 72 and 97% of those infected will develop symptoms.

Symptoms include: sudden onset, sometimes biphasic fever, fevers typically lasting from a few days to a week, fever usually above 102 °F, joint pains, rash, headache, fatigue, nausea, myalgias and vomiting may occur.

Joint pains or stiffness usually lasting weeks or months but sometimes lasting years.

Iridocyclitis, uveitis, and retina lesions may occur.

Typically, the fever lasts for two days and then ends abruptly.

Headache, insomnia and prostration last about five to seven days.

May cause long-term symptoms following acute infection in more than 50% of patients.

Prolonged symptoms are associated with increased age and history of prior rheumatological disease.

An alphavirus with a positive-sense single-stranded RNA genome of about 11.6kb,

A member of the Semliki Forest virus complex.

Three genotypes of this virus: West African, East/Central/South African, and Asian genotypes.

Replicates in fibroblasts, skeletal muscle progenitor cells, and muscle fibers.

Generally spread through bites from A. aegypti mosquitoes.

The most definitive diagnosis is by virus isolation provides, but takes one to two weeks for completion and must be carried out in biosafety level III laboratories.

Differential diagnosis can include dengue, Zika and other infectious and non-infectious diseases, such as septic arthritis and autoimmune disorders.

The disease can be identified by chikungunya viral RNA in the serum, typically detectable until about 5 to 8 days after symptom onset or virus specific IgM antibodies usually detectable by 4 to 5 days after symptom onset and detectable for months to years after.

Serological diagnosis uses an ELISA assay to measure chikungunya-specific IgM levels.

Serological false positives can occur with infection via other related viruses, such as o’nyong’nyong virus and Semliki Forest virus.

The differential diagnosis includes infection with other mosquito-borne viruses, such as dengue, and influenza.

Chronic recurrent polyarthralgia occurs in at least 20% of patients one year after infection.

Prevention of infection by protection against contact with the disease-carrying mosquitoes by mosquito control with insect repellents, and wearing protective clothing, and clothing with repellent properties, and securing the home from mosquito entry.

No specific treatment is available, but includes fluids, and NSAIDs.

Chronic arthritis may be treated with ribavirin and chloroquine.

Steroids are not helpful.

Since 2006 over 200 cases have been reported in the United States, and recently for the first time the virus was passed by mosquitoes to individuals on the U.S. mainland.

Vaccine approved for adult 18 years or older, who are at high risk of exposure to chikungunya virus.

Vaccine associated, however, with neurologic and cardiac events.

Prevention of mosquito bites, offers the best protection against chikungunya.