Chikungunya Fever (CHIKV)

 

 

Overview

Chikungunya (CHIKV) is a viral illness transmitted primarily by mosquito bites. Like dengue and Zika virus, the most common mosquito vectors are Aedes aegypti and Aedes albopictus. Both mosquito species prefer urban environments and are considered “day-biters,” although they are most active in the early mornings and evenings. While seldom fatal, severe and persistent joint pain and swelling after infection can be disabling.  Outbreaks have occurred in countries in Africa, the Americas, Asia, Europe, the Caribbean, and the Indian and Pacific Oceans, but there is also risk for spread to unaffected areas by infected travelers. Imported cases and small outbreaks have occurred in the Southeastern U.S. Regional explosive outbreaks have potential to disrupt military operations.

Prevention is mainly mosquito-bite avoidance, which is best accomplished by careful use of the DoD Insect Repellent System and Insect Repellent Treatment of Military Uniforms and mosquito breeding site elimination. There are now two recently licensed CHIKV vaccines available in the United States: IXCHIQ® is a live-attenuated chikungunya vaccine (CHIK-LA). VIMKUNYA™ is a non-live virus-like-particle chikungunya vaccine (CHIK-VLP). Recommended use remains limited to specific circumstances (e.g. locations with a current, active outbreak per CDC or a prolonged (>6 month) stay in an area of elevated risk). More detailed information may be found at CDC Chikungunya Vaccine Information for Health Care Providers.
 
Locations with active CHIKV can be found here: CDC Chikungunya Risk Areas

Regional outbreaks of chikungunya have potential to disrupt military operations due to intense transmission and potentially disabling cases. In the event of operational cases, early consultation with the supporting Navy Environmental and Preventive Medicine Unit (NEPMU) and the unit’s operation medical command is critical to ensure that prevention activities are optimized.
 

Clinical Features

CHIKV has an incubation period of 4-7 days, with up to 50% of infections being asymptomatic.  Clinically, CHIKV is characterized by the abrupt onset of fever, rash, and joint pain, which can be severe and may include joint swelling. The joints most often affected are fingers, knees, ankles, and feet, often on both sides.  While CHIKV can be confused with dengue and zika, the joint pain and swelling are much more pronounced in CHIKV.  Mortality is very low.  Most patients recover in under 2 weeks, but up to half of patients continue to have joint pain after 6 weeks and some patients have persistent, disabling joint pain for months or even years.  
There is no specific treatment for CHIKV.  Since aspirin and NSAIDs (e.g. Motrin) can be dangerous with dengue, acetaminophen (Tylenol) should be used preferentially for fever and pain control until diagnostic testing rules out dengue.
 

CDC Clinician Fact Sheet (Note: Fact Sheet pre-dates Vaccine availability) 

CDC Clinical Management in Dengue-endemic Areas 

Diagnostic Testing

CHIKV infection should be considered in patients with acute onset of fever and polyarthralgia travelers who recently returned from areas with known virus transmission. Laboratory diagnosis is generally accomplished by testing serum or plasma to detect virus, viral nucleic acid, or virus-specific immunoglobulin (Ig) M and neutralizing antibodies.The Biofire Global Fever Panel contains a test for CHIKV. Confirmatory diagnostic testing can be performed within the DoD at NIDDL (Sept 2023): ChikV-Dengue-Zika Testing 
 

Operational Public Health 

Because up to half of chikungunya cases are asymptomatic, a single known case in an operational environment is a red flag for a larger number of cases. This likely indicates widespread exposure with current undiagnosed cases and imminent symptomatic cases. Operational leaders should be advised of the increased threat, and strict adherence to proper uniform wear and repellent use as described in DoD Insect Repellent System and Insect Repellent Treatment of Military Uniforms is essential to limit future cases.  Mosquito management measures should be implemented, to include larval breeding site reduction (i.e., removal of standing water) and pesticide application if possible and appropriate.  

Public Health Case Management: 

• Ensure appropriate clinical testing is being conducted.  

• Segregate chikungunya patients. House and treat in a screened area away from non-chikungunya patients during their infective period (up to 7 days, which may coincide with fever and viremia) to break the mosquito-human transmission cycle.  While CHIKV is not spread person-to-person, mosquitos become infected by feeding on a chikungunya patient and then transmitting the virus by feeding on another person.  

• Initiate enhanced surveillance for febrile illness, and a line list should be prepared and populated with confirmed and suspected cases. 

• Cases should be reported through DRSi (see <internal link to Diagnostic Testing>). 

• A DHA Case Investigation Worksheet may be used to track individual cases. 

Risk Communication: Work with Public Affairs to implement a dengue public awareness campaign. 

Contact local Preventive Medicine (if available) for support.  The cognizant  Navy and Environmental Unit (NEPMU) can advise and/or assist with case investigation activities, laboratory testing, and vector control measures.

Mosquito Bite Avoidance-Vector Control

• Apply 25-30% DEET or 20% picaridin based repellents on exposed skin and treat clothing with a permethrin-containing product.
• Wear long-sleeved light-colored shirts and pants whenever outdoors or in places where mosquitoes may be present.
• Reduce the number of breeding mosquitoes by removing water from any containers around buildings.
• Limit vegetation around buildings to prevent overgrowth and potential mosquito harborages.

• Aedes Surveillance and Control Plan for US Navy and Marine Corps Installations (NMCPHC)
• NAVMED P-5010-8 Navy Entomology and Pest Control Technology
• DoD Insect Repellent System and Insect Repellent Treatment of Military Uniforms
• AFPMB TG 47- Aedes Mosquito Vector Control
• AFPMB TG 36- PPM against Insects and other Arthropods

Reporting

CHIKV is a nationally notifiable disease.  BUMEDINST 6220.12D requires that all cases of chikungunya must be reported to Preventive Medicine authorities.  Notify your Public Health Emergency Officer, cognizant  Navy Environmental and Preventive Medicine Unit (NEPMU), and state or local health department so that measures can be taken to mitigate the risk of local transmission. NEPMU staff can advise on and/or assist with case investigation activities, laboratory testing, and vector control measures. NMCFHPC Medical Surveillance and Reporting Resources 

Case Classification per Armed Forces Medical Reportable Events Guide

Probable:
A case that meets the clinical description as described above with ALL of the following:  
Confirmed:
A case that meets the clinical description as described above with any of the following:  
Critical Reporting Elements:  Travel and/or deployment history during the incubation period, circumstances of exposure if known (e.g. duty, occupation, environmental factors).

Web Resources

Center for Disease Control and Prevention (CDC):  Chikungunya Virus
Center for Disease Control and Prevention (CDC) “Yellow Book”, 2026: Chikungunya
World Health Organization: Chikungunya
NECE Chikungunya Fact Sheet
 

Policy and Guidance

 

• BUMED Chikungunya Medical and Mosquito Vector Surveillance Message
• OPNAVINST 6250.4C- Navy Pest Management Programs
• DoD Inst 4150.07 DoD Pest Management Program
• NAVMED P-5010-8 Navy Entomology and Pest Control Technology
• AFPMB TG 47- Aedes Mosquito Vector Control
• AFPMB TG 36- PPM against Insects and other Arthropods 

Epidemiology and Publications

NMCFHPC- EpiData Center: *CAC required*   EDC Case Finding Profile
AFHSD MSMR December 2023 Vol. 30 No. 12 Surveillance Snapshot-1Dec2023: Chikungunya in U.S. Servicemembers; 2016-2022
AFHSD MSMR Feb 2021 Vo1 28 No. 2  Surveillance for Vector Borne Diseases among AD, 2016-2020
AFHSD MSMR 2018 Vol 25 No. 2 Surveillance for Vector Borne Diseases among AD, 2010-2016
AFHSD MSMR October 2015 Vol. 22 No. 10 Chikungunya Infection in DoD Healthcare Beneficiaries Jan 2014-Feb2015: Chikungunya infection in DoD Beneficiaries Jan 2014-Feb 2015
Frickmann H, Herchenröder O. Chikungunya Virus Infections in Military Deployments in Tropical Settings-A Narrative Minireview. Viruses. 2019 Jun 14;11(6):550. doi: 10.3390/v11060550. PMID: 31197085; PMCID: PMC6631184. Chikungunya Virus Infections in Military Deployments
Pollett S, Hsieh H-C, Lu D, Grance M, Richard S, Nowak G, et al. (2024) The risk and risk factors of chikungunya virus infection and rheumatological sequelae in a cohort of U.S. Military Health System beneficiaries: Implications for the vaccine era. PLoS Negl Trop Dis 18(8): e0011810. https://doi.org/10.1371/journal.pntd.0011810. IDCRP Article