Page 139 - Journal of Special Operations Medicine - Winter 2014

An Ongoing Series

Chikungunya

Mark W. Burnett, MD

ABSTRACT
Chikungunya is a rapidly emerging infectious disease person, in utero, and intrapartum have also been re-
caused by a virus of the genus Alphavirus, family Toga- ported (Figure 1).
viridae. Most commonly, patients have an acute onset
of fever with often debilitating symmetric joint discom-
fort that can relapse months after the initial infection. Clinical
This infection is typically transmitted by the bite of an More than three-quarters of patients who are infected with
infected Aedes aegypti or Aedes albopictus mosquito, chikungunya become symptomatic. Following an incuba-
vectors that also transmit dengue and yellow fever. Spe- tion period of typically 3 to 7 days, patients experience an
cial Operations Forces Medical Providers should be acute onset of fever with polyarthralgia, a nonspecific mac-
aware of this disease, which is currently being diagnosed ulopapular rash, headaches, nonexudative conjunctivitis,
worldwide. and nausea and vomiting. Lymphopenia, thrombocytope-
nia, and elevated transaminase levels are the most common
Keywords: Chikungunya, infectious disease, virus, mosquito laboratory findings. Joint pain is symmetric and usually
vector involves the ankles, fingers, and wrists. Typical acute symp-
toms resolve in 7 to 10 days; however, arthralgias can per-
sist for months to years and are a key distinguishing feature
from a dengue infection. Deaths following infection are rare
Background
and typically occur in the very young and very old.
Chikungunya is a mosquito-borne illness that was first
described in a 1952 outbreak in the Makonde region Figure 1 This transmission electron micrograph (TEM)
of what is now Tanzania. Its unusual name comes from depicts numerous chikungunya virus particles, which are
the Makonde language verb kungunyala, meaning “to composed of a central dense core that is surrounded by a viral
become contorted,” “to walk bent over,” or “that which envelope. Each virion is approximately 50nm in diameter.
bends up”—a vivid description of the joint discomfort
that commonly occurs with the disease. It is an arthro-
pod-borne single-stranded RNA virus of the genus Al-
phavirus, family Togaviridae.

The primary vectors that transmit the disease are the
Aedes aegypti and Aedes albopictus mosquitoes, which
also transmit dengue and yellow fever. These mosqui-
toes thrive in an urban environment, breeding in small
stagnant, sheltered collections of freshwater such as
in discarded tires and unused pots that have collected
rainwater. They tend to bite and feed during the day- Photo: Cynthia Goldsmith
time hours—especially during the cooler hours of the
day. Humans are the primary host of the infection
and can infect Aedes mosquitoes as they take a blood Source: http://www.cdc.gov/media/DPK/2014/dpk-
meal. Infections following needlesticks from an infected chikungunya.html#graphics

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