LAC DPH Health Advisory
First Probable Case of Chikungunya in LAC in a Returning Traveler
June 24, 2014
• Chikungunya virus infection has been deemed probable in a Los Angeles County (LAC)
resident returning from travel in the Caribbean islands in early May 2014.
• Chikungunya infection should be considered in the differential diagnosis in patients presenting
with acute onset of fever and polyarthralgia who have recently returned from the Caribbean and
other areas with known virus transmission.
• Serum serologic testing for chikungunya antibodies is available at Focus Diagnostics and
California Department of Public Health (CDPH).
• Since December 2013 the Caribbean islands have been experiencing an outbreak-of
chikungunya (over 165,000 cases) with local transmission. Outbreaks have previously been
reported in Africa, southern Europe, southeast Asia, the Indian subcontinent, and islands in the
Indian and Pacific Oceans.
• To date, four confirmed cases have been reported in California. Three additional cases are
being investigated, including the Los Angeles County case.
• Cases of chikungunya should be reported to the Los Angeles County Department of Public
Health (LAC DPH) as an “unusual disease”.
The LAC DPH has recently been notified of a returning traveler with probable chikungunya
infection, caused by a virus transmitted by Aedes aegypti and Ae. albopictus mosquitoes. This is
the first imported chikungunya case reported in LAC this year. The patient presented with fever,
joint aches, and rash while vacationing in the Caribbean islands, including Dominica, St. Kitts,
and Nevus from late April through the first week of May. The patient’s CBC was notable for a
mildly depressed WBC of 3,400. CDPH Viral and Rickettsial Disease Laboratory (VRDL)
serology results confirmed the diagnosis.
Chikungunya virus infection should be considered in patients with acute onset of fever and
polyarthralgia who recently returned from the Caribbean and other areas with known virus
transmission. Laboratory diagnosis is accomplished by testing serum to detect virus, viral nucleic
acid, or virus-specific immunoglobulin M (IgM) and neutralizing antibodies. During the first
week of illness, chikungunya virus infection can often be diagnosed by using viral culture or
nucleic acid amplification on serum. Virus-specific IgM and neutralizing antibodies normally
develop toward the end of the first week of illness. To definitively rule out the diagnosis,
convalescent-phase samples should be obtained from patients whose acute-phase samples test
negative. Chikungunya virus diagnostic testing is performed CDPH, Centers for Disease Control
and Prevention (CDC) and Focus Diagnostics. Healthcare providers can contact LAC DPH to
facilitate testing.
A majority of people infected with chikungunya virus become symptomatic. The incubation
period is typically 3–7 days (range: 2–12 days). The most common clinical findings are acute
onset of fever and polyarthralgia. Joint pains are often severe and debilitating. Other symptoms
may include headache, myalgia, arthritis, or rash. Persons at risk for more severe disease include
neonates (aged <1 month) exposed intrapartum, older adults (e.g., > 65 years), and persons with
underlying medical conditions (e.g., hypertension, diabetes, or cardiovascular disease).
As of June 13, 2014, local transmission had been identified in 19 countries or territories in the
Caribbean or South America. A total of 165,990 suspected and 4,576 laboratory-confirmed
chikungunya cases had been reported from these areas. Outbreaks have been reported in Africa,
southern Europe, southeast Asia, the Indian subcontinent, and islands in the Indian and Pacific
Oceans. California has documented four confirmed and three probable cases of chikungunya
earlier this year who returned from the Caribbean and the south Pacific. LAC DPH has
documented imported chikungunya cases previously in 2006 and 2007 when there was a large
outbreak on the Indian subcontinent.
The Aedes aegypti (yellow fever) mosquito and Ae. albopictus (Asian tiger) mosquito are
important vectors of chikungunya and other arboviruses such as dengue. Ae. albopictus have
been detected in LAC in 2011-2014 in El Monte and Arcadia. Ae. aegypti mosquitoes have been
detected in San Mateo, Fresno and Madera counties in 2013 and 2014. Local vector control
districts are working closely with LAC DPH to enhance surveillance and attempt eradication of
these invasive mosquitoes. The presence of these mosquitoes capable of transmitting dengue and
chikungunya is concerning; at this time, however, there is no evidence of local transmission of
these viruses.
Given the concern for potential local transmission of chikungunya and dengue in or near areas
where Ae. aegypti and Ae. albopictus mosquitoes have been found, suspect cases of chikungunya
and dengue should be reported promptly to LAC DPH. Chikungunya can be reported as an
“Unusual Disease” at this time. California regulations require physicians and laboratories to
report all positive laboratory tests for Dengue to the patient’s local public health department
within one working day (California Code of Regulations, sections 2500 and 2505). To file a
report of a suspect case, a completed Confidential Morbidity Report (CMR), available at
http://publichealth.lacounty.gov/acd/reports/cmr-h-794.pdf, can be faxed to the DPH Morbidity
Unit at (888) 397-3778. You may also report cases by telephone during normal business hours
from 8:00 a.m. to 5:00 p.m. to (888) 397-3993.
For cases among residents of the Cities of Long Beach or Pasadena, please contact their local
health departments:
• City of Long Beach Health Department: 562-570-4302
• City of Pasadena Health Department: 626-744-6000
More information:
• For medical consultation regarding chinkungya, dengue and other arboviral infections
including disease surveillance and test interpretation, contact ACDC at (213) 240-7941 during
normal business hours. Critical after-hours consultation is available by contacting doctor on call
at (213) 974-1234.
• CDPH VRDL Guidelines for Laboratory Services:
http://www.cdph.ca.gov/programs/vrdl/Pages/default.aspx
Countries and Territories Where Chikungunya Have Been Reported
AFRICA
OCEANIA/PACIFIC
AMERICAS
ISLANDS
 Benin
 Anguilla
 Federal States of Micronesia
 Burundi
 Antigua and Barbuda

New
Caledonia
 Cameroon
 British Virgin Islands

Papua
New
Guinea
 Central African Republic
 Dominica
ASIA
 Comoros
 Dominican Republic
 Democratic Republic of
 Bangladesh
 French Guiana
the Congo
 Bhutan
 Guadeloupe
 Equatorial Guinea
 Cambodia
 Guyana
 Gabon
 China
 Haiti
 Guinea
 India
 Martinique
 Kenya
 Indonesia
 Puerto Rico
 Madagascar
 Laos
 Saint Barthelemy
 Malawi
 Malaysia
 Saint Kitts and Nevis
 Mauritius
 Maldives
 Saint Martin
 Mayotte
 Myanmar (Burma)
 Sint Maarten
 Nigeria
 Pakistan
 Saint Lucia
 Republic of Congo
 Philippines
 Saint Vincent and the
 Reunion
Grenadines
 Singapore
 Senegal
 Turks and Caicos Islands
 Sri Lanka
 Seychelles
 US Virgin Islands
 Taiwan
 Sierra Leone
 Thailand
 South Africa
 Timor
 Sudan
 Vietnam
 Tanzania
 Yemen
 Uganda
 Zimbabwe
EUROPE
 Italy
 France