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Being aware of the “Chik” sign in the current arbovirus renaissance

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By Warren R. Heymann, MD
April 24, 2016

As the world focuses its attention on the Zika virus, with its profound complications of microcephaly in neonates and Guillain-Barré in adults, we cannot ignore other arboviruses that may cause devastating illness – Dengue Fever and Chikungunya Fever.

All of these are transmitted by the same vectors, predominantly Aedes aegypti but also by Aedes albopictus. While the former is distributed in the tropics, the latter is found in temperate climates. This has the potential to allow emergence of these infections to larger, more widely disseminated populations.

Admittedly, when I went to the American Dermatological Association last October, before ever have heard of the Zika virus, I was truly concerned about the risk of Chikungunya, as there had been more than 10,000 cases reported in Puerto Rico the year before. It was not the fever and rash that worried me – it was the potential for severe arthritis that could last for months. This was compounded by the fact two weeks prior to the meeting, I had just diagnosed (and confirmed) that a woman admitted to Cooper with high fever and a morbilliform rash had the disease. At conference I put so much DEET on myself, I’m surprised that I did not have a seizure!

The fact is that anytime we see a patient with fever and rheumatologic complaints, we must include Chikungunya in our differential diagnosis.

I read a fascinating case report (1) and two outstanding commentary/review (2,3) about Chikungunya. They offer excellent reviews about the multiple dermatologic and systemic findings of the disorder. The purpose of this comment is to inform you of a dermatologic finding that I had never heard of — the “Chik” sign.

Varsani et al reported a 12 day old neonate who presented with ill-defined dark centrofacial pigmentation with flagellate pigmentation on the trunk and patchy pigmentation on the extremities. The mother had fever in the peri-partum period. It was the pigmentation in the child that was the only clue that suggested (and subsequently confirmed) the diagnosis of Chikungunya. The cause of the hyperpigmentation remains an enigma – presumably it is post inflammatory in nature (1).

Hyperpigmentation has been reported in 42% of cases in a series from South India. There are three types of hyperpigmentation — centrofacial, freckle-like and diffuse. Flagellate pigmentation may occur. (2) The Chik sign itself refers to pigmentation on the nose, and may persist for up to 6 months. Although it clearly helped suggest the diagnosis in the case report about the neonate, most often the sign would be useful in considering the diagnosis retrospectively.

As the world has been warmer, and controlling mosquito populations more difficult, all of these arbovirus infections should be front and center in our clinical considerations. Be on the lookout for the Chik sign in the appropriate clinical context.

1. Vasani R, et al. Congenital Chikungunya – a cause of neonatal hyperpigmentation. Pediatr Dermatol 2016; 33: 209-212.
2. de Chiara Macarenco A. Chikungunya: What we need to know. Pediatr Dermatol 2016: 33: 238-240.
3. Sehgal VN, et al. Chikungunya. SKINmed 2016; 14: 12-15.

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