Kawasaki disease is a disease that affects children and leads to inflammation of blood vessels (vasculitis). Approximately 85-90% children below the age of 5 years and 90-95% children below the age of 10 years are affected by it. The most common blood vessels affected are the medium sized vessels; however, other blood vessels including large vessels, small arterioles, veins and capillaries can also be affected by the disease. It has a high propensity to affect coronary arteries, especially in untreated cases, leading to the complication of coronary artery aneurysms.
What Is The Most Likely Cause Of Kawasaki Disease?
The cause of Kawasaki disease is not properly understood at this moment and for the most part its etiology still remains unclear. Although, the most probable cause is still unknown, Kawasaki disease has been strongly linked to infections; however, no solid connection has been found with any specific infectious agent. Possible connection with genetics and autoimmunity has also been proposed, but there still exists gap between the thesis and clinical implications. (1)
Infection. Various infectious agents have been implicated in the initiation of Kawasaki disease including, parvovirus B19, adenovirus, rotavirus, EBV, CMV, parainfluenza type 3 virus, measles, human lymphotropic virus, neisseria meningitidis, rickettsia, bacterial toxin-medicated superantigens, Klebsiella pneumoniae, Mycoplasma pneumoniae, tick borne diseases, mite associated bacteria and propionibacterium acnes. Kawasaki disease is more common in late winters and spring, which raises suspicion for an infectious cause. It is also uncommon in infants less than 4 months of age, most likely related to maternal antibodies providing passive immunity. However, what is interesting to know that, it is not a transmissible disease and cannot be passed from one child to another. There is also hypothesis that it has a waterborne vector.
Researchers have found cytoplasmic inclusion bodies containing RNA in about 85% cases of Kawasaki disease. This finding strongly suggests the role of a RNA virus that may lead to the disease in genetically predisposed individuals.
Genetics. There is a strong suspicion for genetic factors playing a role in the etiology of Kawasaki disease. It has been noted that there is 10-20 times greater chance of Kawasaki disease in siblings and twin of affected child. In addition, children born to parents with Kawasaki disease have a severe form of the disease and chances of recurrence are very high. Researchers have also found multiple family members affected by Kawasaki disease. Major histocompatibility complex antigen has also been found in patients with Kawasaki disease. Polymorphism of ITPKC (inositol 1,4,5-triphosphate 3-kinase C) gene has been linked to greater chances of developing coronary artery lesions in both Japanese and American children. Genetic factors have been associated with the development and progression of coronary artery lesions.
Although, the interplay of infectious etiology and genetic factors have been strongly linked to and considered to be the reason for Kawasaki disease, there is still not clear understanding how and which infectious agent is the real culprit. Although, the suspicion for genetic factor in the etiology is very high, the genetic factors application in the diagnosis and treatment of the disease is still not clearly understood. More studies and research are underway and hopefully will provide relevant answers in future.
Kawasaki disease is of two types, complete and incomplete. The diagnosis of complete Kawasaki disease is based on the presence of high fever for at least 5 days along with 4 or 5 principal clinical presentations. Whereas, the diagnosis of incomplete Kawasaki disease is based on the presence of fever for more than 5 days, in addition to 2-3 principal clinical features. Incomplete Kawasaki disease needs further laboratory work up. The principal clinical features of Kawasaki disease include oropharyngeal changes (diffuse erythema, bleeding, fissuring, crusting of lips, strawberry tongue), extremity changes (erythema of palms and soles, desquamation of fingers and toes, Beau’s lines), skin rash (diffuse maculopapular rash), unilateral cervical lymphadenopathy (lymph node size of at least 1.5 cm) and bilateral bulbar conjunctivitis.
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