Arboviral Diseases

Types of Arboviral Diseases

NEUROINVASIVE ARBOVIRAL disease results in severe encephalitis (brain inflammation) or paralysis. An example of a neuroinvasive arboviral diseases is: 

• Japanese Encephalitis Virus (JEV) – Japanese encephalitis virus, transmitted to humans through the bites of infected Culex species mosquitoes, is the leading cause of vaccine-preventable encephalitis in Asia and the western Pacific. For most travelers to Asia, risk for Japanese encephalitis is very low but varies based on destination, length of travel, season, and activities. Most people infected with Japanese encephalitis do not have symptoms or have only mild symptoms. However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including headache, fever, disorientation, seizures, weakness, and coma.
  Sources: CDC – JEV, Military (DHA) Communicable Disease Toolkit for clinical reporting guidance 
  

NON-NEUROINVASIVE ARBORVIRAL diseases are the most common form of arboviral diseases and are associated with acute fever with other possible symptoms such as aches and pains (headaches or eye pain behind the eyes, muscle, joint, or bone pain), nausea/vomiting, and/or rash. Rest, fluids, and pain medications may relieve symptoms, but there are no disease-specific treatments. Examples of non-neuroinvasive arboviral diseases include:

• Chikungunya​ – Chikungunya is a mosquito-borne viral disease spread usually by infected Aedes albopictus and Aedes aegypti mosquitoes. Outbreaks have occurred in Africa, the Americas, Asia, Europe, and islands in the Indian and Pacific Oceans. Most people who are infected will develop symptoms, usually 3-7 days after bitten by the infected mosquito. While a chikungunya vaccine​ has been developed and may be recommended for some travelers, the DOD is not currently requiring it for Service members.
  Sources: DHA Public Health – Chikungunya, CDC – Chikungunya​, Military (DHA) Communicable Disease Toolkit​ for clinical reporting guidance 
  

• Dengue – Dengue is a mosquito-borne arboviral disease caused by any of four related viruses (dengue virus 1, 2, 3, and 4). Dengue viruses are mainly spread to people by the bite of an infected Aedes mosquito. A person can be infected with dengue multiple times in their life. Symptoms usually begin within 2 weeks after being bitten by an infected mosquito and typically last 2–7 days. Most people will recover after about a week. There is a dengue vaccine but only for children who live in high-risk areas.
  Sources: DHA-Public Health – Dengue​, ​CDC – Dengue, Military (DHA) Communicable Disease Toolkit for clinical reporting guidance 
  

• ​Yellow Fever – Yellow fever virus is spread through the bite of an infected mosquito that most commonly occurs in tropical and subtropical areas of Africa and South America. Named for its symptom of yellowish skin or eyes, initial symptoms can be general (fever, chills, severe headache, back pain, general body aches, nausea, vomiting, fatigue, and weakness). Most people infected with yellow fever virus will either have no symptoms or mild symptoms and completely recover. For people who develop symptoms, the time from infection until illness is typically 3 to 6 days. Most people who develop symptoms improve within one week. For some people who recover, weakness and fatigue might last several months. The more severe symptoms that can develop are high fever, yellow skin or eyes, bleeding, shock, and organ failure. There is no specific treatment for yellow fever. Vaccination is recommended for travelers going to yellow fever risk areas. The military requires a vaccines of Service members prior deploying to areas that yellow fever occurs. The vaccine and procedures to reduce or eliminate exposure (mosquito biting) appear to have reduced the rates of this VBD in the U.S. over the last two decades.
  Sources: CDC – Yellow Fever​, Military (DHA) Communicable Disease Toolkit for clinical reporting guidance 
  

• West Nile Virus – West Nile virus is most commonly spread through the bite of an infected mosquito. Its name may not convey the problem that West Nile virus is in the U.S.; West Nile virus is the leading cause of mosquito-borne arboviral disease in the continental U.S. Risks are highest during mosquito season (summer through fall). Symptoms of West Nile virus disease include fever, headache, body aches, vomiting, diarrhea, or rash. Fortunately, most people infected with West Nile virus do not feel sick. About 1 in 5 people who are infected develop a fever and other symptoms. About 1 out of 150 infected people develop a serious, sometimes fatal, illness. Most people infected with West Nile are believed to have lifelong immunity or protection from getting the disease again. Some people who have weakened immune systems from certain conditions or medications might not have a strong immune response to the initial infection or their immunity may wane over time. There are no vaccines to prevent West Nile virus in people, and there is no specific treatment for West Nile virus (antibiotics do not treat viruses). Laboratory testing of blood or spinal fluid is needed to confirm diagnosis.
  Sources: DHA-Public Health – West Nile Virus, CDC – West Nile Virus, Military (DHA) Communicable Disease Toolkit for clinical reporting guidance 
  

• Zika – Zika is a mosquito-borne arboviral disease that is transmitted both through the bite of an infected mosquito (usually the Aedes mosquito) AND may also be passed through sexual activity from a person infected with Zika. Per CDC, people infected with Zika virus (e.g., from an infected mosquito bite) can transmit the disease through sex weeks to months after a bite, even if they do not have symptoms. Zika can be passed from a person before symptoms start, while they have symptoms, and after symptoms end. The virus can stay in semen longer than in other human body fluids. Many people infected with Zika virus will not have symptoms or will only have mild symptoms, and they may not know they have been infected. Symptoms (i.e., fever, rash, headache, joint or muscle pain, red eyes) may be similar to those of other arboviral diseases (dengue and chikungunya). Symptoms can last several days to a week. Most persons do not seek hospital care. However, Zika can cause serious birth defects when transmitted from a pregnant woman to her fetus. Women who are pregnant, or those who do not yet know they are pregnant, may be infected if bitten by a mosquito carrying the Zika virus or by their partner even months after they were infected. Seek advice of an OB/GYN provider if you believe you may be infec​ted with Zika. Zika virus disease risk is reduced by protecting from mosquito bites, and using condoms or not having sex. Timeframes for preventing sexual transmission of Zika start as soon as the person returns from travel, even if they do not have symptoms, or from the start of their symptoms or the date they were diagnosed. Men should use condoms or not have sex for at least 3 months. Women should use condoms or not have sex for at least 2 months. Though the military was able to help CDC and other world-wide public health organizations address the notable Zika virus outbreaks in 2015 and 2016, transmission of Zika continues to be a threat to the military population in certain areas of the world. Threat information for Zika can be inconsistent, so check recent threat information prior travelling to a region.
  Sources: CDC – Zika, Military (DHA) Communicable Disease Toolkit for clinical reporting guidance​.