Rheumatoid Arthritis and Chikungunya Similarities and Differences
An Autoimmune Disease and an Infection
Rheumatoid arthritis is an autoimmune condition in which the body's immune system mistakenly attacks joints in the body. Chikungunya is an infectious disease caused by a virus entering the body through a mosquito bite. At first glance, the two disorders seem completely different. Some of their symptoms are so similar that it may be hard for a doctor to make a correct diagnosis without a very specific type of blood test, however.
Chikungunya infections are present in Asia, Europe, and Africa and on islands in the Indian and Pacific Oceans. Recently, they have also appeared in North, Central, and South America and in the Caribbean. Some health experts suspect that chikungunya will become more common in North America. Distinguishing a chikungunya infection from rheumatoid arthritis is therefore very important.
According to WHO (the World Health Organization), the name "chikungunya" is derived from a word in the Kimakonde language of the Makonde people in Tanzania. The name means "to become contorted". This phrase refers to the stooped posture that some people assume due to the severe joint pain produced by the viral infection.
The Cause of Chikungunya
The chikungunya virus is transmitted through a bite by two species of mosquitoes—Aedes albopictus and Aedes aegypti. These are normally inhabitants of tropical and subtropical areas, but both have been introduced to the United States.
At the moment, most North Americans that have chikungunya have just returned from a trip to a tropical country inhabited by the mosquitoes. Unfortunately, the insects are spreading to new areas. This is especially true for Aedes albopictus, which can survive in temperate climates as well as tropical ones. A few people have developed chikungunya after a mosquito bite in the US as opposed to a bite in another country.
When a female mosquito bites someone to suck up blood, she injects an anticoagulant to stop her victim's blood from clotting. (Only female mosquitoes bite.) The virus enters the victim's blood in the mosquito's saliva. Later, when an uninfected mosquito bites the victim to withdraw blood, she may also withdraw the virus. If the virus survives in the new mosquito, the insect is then capable of infecting someone else. Chikungunya symptoms may develop in as little as two to as long as twelve days after a mosquito bite.
Possible Symptoms and Treatment
Some people never develop symptoms from a chikungunya virus infection, but most do. The most common effects are fever and severe joint pain, which is often disabling. Other possible symptoms include swollen joints, muscle pain, a rash, a headache, and nausea.
At the present time, there is no medication available to treat chikungunya. Antibiotics aren't helpful because they don't destroy viruses. The body is nearly always able to defeat the chikungunya virus by itself, however, and fatalities are rare. They are most common in elderly people.
Even though chikungunya is rarely dangerous, it's very unpleasant and often painful. It can also produce lingering effects that may last for a long time. One of the symptoms which may linger—even for years—is the joint pain.
Anyone with unexplained symptoms should visit a doctor. In the case of chikungunya, the doctor may prescribe pain killers, rest, and fluids. He or she may also offer other suggestions to help the patient.
Incidence of Locally Transmitted Disease
According to the CDC (Centers for Disease Control and Prevention), from 2006 to 2013 all cases of chikungunya in the United States appeared in people who had travelled to other countries and become infected there. This conclusion was based on the illnesses that were diagnosed and reported.
- In 2014, twelve cases of chikungunya acquired from a mosquito bite within the United States were reported. They all occurred in Florida. (As in the following years, a higher number of cases was reported in travellers to other countries.)
- In 2015, another case arising within the United States was reported. This infection occurred in Texas.
- In 2016, no cases of locally transmitted chikungunya in the United States were reported.
- It should be noted that in 2014 to 2016 amost all of the cases in Puerto Rico were locally transmitted.
While the number of cases caused by mosquitoes within the United States may not sound significant, it shows that at least some of the mosquitoes in the country are (or were) capable of carrying the chikungunya virus. The situation needs to be watched carefully.
What Is Chikungunya?
Currently, researchers say that the chikungunya virus isn't transmitted from person to person. There may be one exception, however. According to the CDC, "Chikungunya virus is transmitted rarely from mother to newborn around the time of birth."
Preventing Mosquito-Borne Diseases
The best way to prevent chikungunya or other mosquito-borne diseases is to use insect control and avoidance techniques. Standing bodies of water where mosquito larvae grow should be drained. Even a small puddle is an attractive place for a female to lay eggs. Protective clothing should be worn in areas frequented by mosquitoes. Insect repellents are also helpful. Doors and windows should have screens. Mosquito nets over beds are useful in areas where lots of the insects are found.
How Does Rheumatoid Arthritis Develop?
In rheumatoid arthritis, or RA, the immune system attacks a thin membrane called the synovium. The synovium is also known as the synovial membrane. This membrane lines the capsule around many of our joints, which are known as synovial joints.
The immune system's attack involves inflammation. The inflammation causes the synovium to thicken. Eventually the inflammation from the synovium spreads to the cartilage and bone in the joint and causes these structures to break down. The damage may stop the ligaments, tendons, and muscles around the joint from doing their jobs and may eventually lead to deformity in the affected area.
The trigger for the immune system's attack is unknown. There seems to be a genetic component to the disorder. The possession of a certain gene or genes is thought to make a person more susceptible to an environmental trigger that leads to joint damage. The trigger might be a viral or bacterial infection or a hormonal change. Neither of these theories have been proven, though.
A Rheumatologist Discusses Rheumatoid Arthritis
Possible Symptoms of the Disease
Someone with rheumatoid arthritis will probably find that their joints feel warm, tender, and swollen. The joints may also look red. The person may experience stiffness, especially after getting out of bed in the morning. They may experience fatigue, low energy, and an occasional fever as well.
The joints in the hands and wrists are most commonly affected, usually on both sides of the body. Other joints may also be affected by the disorder, however.
RA may involve symptoms in other parts of the body in addition to joints. A decrease in red blood cells, or anemia, is a possible symptom. The patient may also experience a dry mouth and dry eyes. Rarely, the blood vessels or the membrane around the lungs or heart may become inflamed.
There is considerable variability in the seriousness of rheumatoid arthritis. Some people experience flare-ups (periods when their symptoms are worse) alternating with remissions (periods when their symptoms are much weaker or absent). For other people, the symptoms are constant. The symptoms remain mild for some people, but for many people they are progressive. New medications can weaken this progression, however.
Living With Rheumatoid Arthritis
Possible Treatments for the Disease
Anyone with rheumatoid arthritis or joint pain must be under the care of their doctor, who will prescribe treatment. There are many potentially effective treatments available. Some are more effective for certain patients than others, however.
A relatively new treatment that is often very effective is the use of DMARDS (disease-modifying antirheumatic drugs). These are medications that suppress the patient's overactive immune system, interfering with the inflammation that is damaging the joints. Methotrexate is a commonly prescribed DMARD, but there are others.
One important group of DMARDs is the biologics, which are mentioned in both of the arthritis videos above. Biologics are medications produced by genetic engineering. They are proving to be very useful for some cases of rheumatoid arthritis.
Diagnosing the Disease
One reason that RA may be misdiagnosed—at least in the early stage—is that there is no test that proves that someone has rheumatoid arthritis. Inflammation and painful joints can be part of other diseases. Joint X-rays may look normal or only slightly abnormal in the early stage of RA.
There are blood tests which can strongly suggest that someone has rheumatoid arthritis, but they aren't conclusive. Many people with RA tend to have distinctive factors in their blood. Not everyone with RA has these factors in their blood, however, and some people have the factors without having RA.
Generally, a doctor makes a diagnosis of rheumatoid arthritis based on a combination of a patient's symptoms, an examination, and multiple lab tests.
A Comparison of Rheumatoid Arthritis and Chikungunya
The symptoms of rheumatoid arthritis follow a different pattern of development from those of chikungunya. Chikungunya begins with a fever while rheumatoid arthritis generally doesn't, for example. Symptoms of joint pain caused by the chikungunya virus generally appear suddenly and are severe, while those of rheumatoid arthritis appear more slowly and gradually worsen. After the initial symptoms of chikungunya have subsided and only joint pain remains, however, it can be difficult to tell the two diseases apart.
A blood test is often unhelpful in distinguishing the two diseases. Both disorders involve an elevated blood level of a specific type of T-cell, for example. In order to positively identify chikungunya, a blood test has to show antibodies to the virus in the patient's blood. Unfortunately, at the moment this type of blood test is only available at the CDC and at specific research laboratories.
Why Does it Matter if the Two Diseases Are Confused?
Early and effective treatment of rheumatoid arthritis is very important because it can delay and reduce joint damage. If someone with rheumatoid arthritis believes that their joint pain is a result of a chikungunya infection, they may take pain killers to feel more comfortable but take no medications to help protect their joints. Joint damage could therefore continue unabated.
On the other hand, if someone with a chikungunya infection is diagnosed with rheumatoid arthritis, they may be prescribed immune system suppression drugs that they don't need. All drugs have side effects. While these side effects may be a small price to pay for someone who is trying to prevent permanent joint damage, relieve pain, and and lead a relatively normal life, they may be unpleasant and unnecessarily harmful for someone with chikungunya. Suppressing the immune system may also make the patient more susceptible to infections.
Rheumatoid Arthritis and Chikungunya in the Future
I hope that the blood test that distinguishes chikungunya from rheumatoid arthritis becomes more widespread. I suspect that it will if chikungunya becomes more common in North America. It would also be wonderful if an antiviral drug or a vaccine is developed for the infection.
Studying the way in which the chikungunya virus causes joint pain may help researchers learn more about the pain caused by rheumatoid arthritis. RA can be a major health problem, yet it's still not completely understood. Although there's no evidence that the chikungunya virus causes the same effects inside joints as rheumatoid arthritis, there may be some similarities. Studying the viral infection may be important not only to help people who are infected by the virus but also to help people with other diseases that affect joints, including rheumatoid arthritis.
The CDC (Centers for Disease Control and Prevention) maintains a webpage containing current news about the spread of chikungunya in the United States.
The NIH (National Institutes of Health) maintains a webpage with detailed information about rheumatoid arthritis.
WebMD discusses biologics for rheumatoid arthritis.
This report from the Washington University School of Medicine in St. Louis discusses the shared symptoms of chikungunya and rheumatoid arthritis.
Questions & Answers
© 2015 Linda Crampton