Mosquitoes are all abuzz in the news lately. The little buggers may look innocuous, but certain species can make you seriously ill, especially in tropical locales.
Worldwide, mosquito-borne diseases account for millions of illnesses annually.
While we usually associate these kinds of things with steamy, equatorial jungles, there are actually a surprising number of mosquito-borne illnesses found all over the United States as well.
You may be wondering…”am I in danger?”.
If you live in or will be traveling to a mosquito hotspot, you definitely need to arm yourself with some information.
Let’s discuss the most common diseases carried by mosquitoes, how they’re transmitted, and how to protect yourself at home and abroad.
Malaria is undoubtedly the most famous of the mosquito-borne diseases, and rightfully so. This devastating illness claims more than a million lives each year.
It originated in sub-Saharan Africa, but, thanks to the age of global travel, has spread to most tropical areas of the world.
Malaria is caused by a protozoan called Plasmodium, carried by the female Anopheles mosquito. The mosquito bites an infected person or animal, the organism matures in her gut, and the infection is reintroduced into another person.
The protozoa infect the red blood cells, causing them to burst open and unleash a violent wave of illness, including high fever, body aches, abdominal pain, vomiting, and diarrhea.
And it doesn’t just go away. Plasmodium can reemerge from dormancy and cause recurrent illness for years, if not treated.
Malaria has developed a broad range, and is found in Africa, parts of south Asia, Central and South America, the Caribbean, and the Middle East.
Urban locales are generally safe, but if you are travelling to any forested or rural areas, be sure to use mosquito protection.
Antimalarial medications are effective, but not without side effects. Check with your doctor to see if meds might be necessary for your particular destination.
2. West Nile virus
West Nile virus is a relatively new disease. As its name implies, it originated in the West Nile district of Uganda in the early 1900s, and has spread globally through both bird and human migrations, landing at the US doorstep in 1999.
The vectors are a couple of different species of Culex (house mosquitoes), a family of mosquitoes that are responsible for several other blood-borne infections as well.
West Nile is common all over the world, but has also invaded almost every state in the continental US, with the greatest concentration in the western states, particularly southern California and southern Arizona.
Although most healthy people can clear West Nile from their system, the virus can cause meningitis-like symptoms in some, including neck stiffness, stupor, lasting fatigue, and severe central nervous system complications.
Elderly people or those with compromised immune systems should take extra precautions to avoid contracting this illness.
You have probably been seeing lots of news about Zika virus in the last couple of years.
Scientists have been aware of the virus for over fifty years in Africa, but its sudden emergence and deep impact in the Americas garnered quite a bit of medical and media attention.
Following an outbreak in Brazil, the virus turned up in a summer outbreak in Miami in 2016, prompting emergency intervention by the CDC and almost frantic mosquito-reduction programs throughout Florida.
Zika virus is both mosquito-transmitted and sexually transmitted. The offending bug can be either Aedes aegypti or Aedes albopictus.
The major concern with Zika is that it has an extra strong potential for neurological damage in healthy victims, and for pregnant women, it can be absolutely devastating.
The virus causes severe deformities in the brain/skull development of unborn children, a condition known as “microcephaly”.
The rise of Zika has definitely impacted travel to the affected regions, especially with the threat presented to expecting families. If you are a pregnant traveler, definitely seek advice before traveling to a Zika-affected area.
Chikungunya virus is one of the milder mosquito-borne infections that you can aquire. Carried by infected Aedes species of mosquitoes, the virus will produce symptoms in most people.
It causes mild flu-like complaints along with its characteristic feature, persistent joint pain and swelling. If you’ve been infected once, you are generally immune to subsequent infections.
Chikungunya is found in parts of Africa, Asia, India, the Caribbean, and heavily throughout the Americas, including most US states.
Not deadly, but not fun.
Dengue fever made the transition from primates in Africa and Southeast Asia to humans approximately 100 to 800 years ago. The mosquito vectors are the same two Aedes species responsible for Zika virus and Chikungunya.
During WWII, major global transport of packaging and troops,along with some stowaway mosquitoes, caused the virus to be disseminated worldwide.
Today, it’s found in over 100 countries across Africa, Asia, the Pacific, South America, the Caribbean, and eastern Australia.
I won’t mince words here. This virus is bad. The mildest form of this disease is quaintly known as “break-bone fever”, which tells you pretty much everything.
Symptoms of severe bone and joint pain accompany a high fever, headache, and malaise. An advanced (but fortunately rare) stage of Dengue is classified as a hemorrhagic fever, which causes bloody vomiting and diarrhea, with possible organ damage and weeks or months of recovery.
This virulent organism sickens about 400 million per year worldwide and conveys a worrisome mortality rate.
The highest risk of Dengue fever occurs during cyclic community outbreaks in its endemic areas, so pay attention to travel advisories if you’re planning on visiting those areas.
A brand new vaccination against Dengue was approved in 2015 by the French pharmaceutical company Sanofi, but so far only Mexico, the Philippines, and Brazil have begun to administer it.
6. St. Louis encephalitis
Its name sounds pretty ominous, but St. Louis encephalitis, or SLE, is not as toothy as some of the other mosquito-borne illnesses.
It’s a viral infection that has the potential to cause headaches, brain swelling, and other neurological symptoms, but only does so in about one percent of those infected, which is good news. Most people never know they have it.
SLE is found from Canada to the tip of South America, but interestingly, the only reports of outbreaks in humans have come from the central and southern United States.
Children and healthy people are usually resistant, but elderly people are at the highest risk of developing the encephalitis part of it, which can be debilitating or even (very rarely) fatal.
7. LaCrosse encephalitis
LaCrosse encephalitis occurs in the American midwest, mid-Atlantic, and southeastern United States. It’s carried by an unusually aggressive mosquito called Aedes triseriatus, the tree-hole mosquito, whose most notable characteristic is a tendency to come out even during the daytime.
LaCrosse encephalitis, like most diseases in its category, is a viral illness that has the potential to invade neurological tissues in its most severe state.
Most people suffering the illness will have mild, flu-like symptoms that go away within a few days, but some may develop the more severe form of the disease, and may need hospitalization.
There is no cure for LaCrosse or any other viral disease, only management of the most dangerous or painful symptoms.
If you are traveling in these states during spring and summer, be sure to extend your mosquito protection beyond the twilight hours to ensure this diurnal critter doesn’t transmit the virus to you or your family.
8. Eastern equine encephalitis
Though fortunately a rare disease, eastern equine encephalitis is caused by a virulent Alphavirus capable of causing severe neurological damage.
EEE virus is transmitted by the bite of the mosquito Culiseta melanura, found in hardwood swamps and other damp areas in the deep south, the eastern seaboard, Michigan, and rural New York, with sporadic occurrences in a handful of other states.
Most people who contract EEE virus will develop symptoms of some kind. They may be only systemic, with no neurological involvement, such as fever, chills, malaise, and general weakness.
Those unlucky enough to progress to encephalitis can experience terrible headaches, seizures, confusion, and even coma.
About one third of people with neurological EEE die from it, and those that recover often have to battle brain damage and neurological deficits afterward.
Only about 7 people per year contract this illness in the US, which means it’s not common to run into it, but EEE is so potentially dangerous that mosquito precautions in these areas must be observed.
9. Yellow fever
Yellow fever strikes in and near the jungles of central Africa and South America. It’s caused by yet another viral infection carried by the mosquito Aedes aegypti, a common culprit.
Most people who come into contact with the virus will clear it without symptoms, but an unlucky few will develop serious illness. The germ attacks the liver, causing liver inflammation, abdominal pain, vomiting, diarrhea, and eventually jaundice, the yellowed skin discoloration from which it gets its name.
Yellow fever is one of the illnesses for which a vaccine is available, and may actually be required for entry into certain areas, especially for an extended period.
Be sure to check the entry requirements for this one if you plan to travel through yellow fever-endemic areas.
10. Japanese encephalitis
Japanese encephalitis can be contracted throughout Asia, including Indonesia and Papua, New Guinea. It is generally milder than some other encephalitis viruses, but a fraction of infected people can go on to develop serious neuroinvasive disease.
The mosquito to blame in this case is Culex tritaeniorhynchus.The good news about Japanese encephalitis is that there is a readily available vaccine to prevent illness.
The virus is pretty much limited to rural areas, where it maintains a complex life cycle with a number of intermediate hosts like birds and pigs, and a few unlucky people.
If you will be traveling to high-risk rural areas in Asia, talk to your doctor about whether or not you need to be vaccinated in advance.
11. Lymphatic filariasis
Lymphatic filariasis is very different type of mosquito-vectored disease. It is caused by microscopic, parasitic worms called Wuchereria bancrofti. Several unrelated mosquito species can transmit it from one infected person to another.
The worms invade the human lymphatic system where they reproduce continually, eventually causing lymphedema, a large collection of fluid in the arms or legs. Antiparasitic treatments are very effective.
The worms are endemic to central Africa, southeast Asia, and a small part of northeastern South America.
According to the CDC, tourists need not fear these little buggers. It takes numerous exposures over several years to develop a pathological state, and short-term visitors are not really at risk.
If you live in or plan to relocate to these areas, though, be advised of the danger.
Tularemia is more commonly known as “rabbit fever” because it’s usually spread by the bites of arthropods to and from infected rodents, and on to people. This is the case in the US and most of the world.
However, if you happen to be headed to Sweden or Russia during the summer months (seriously, who would visit Russia in the winter?), beware the mosquitoes.
Two breeds of the flying menaces, A. cineras and O. excrucians, have evolved the ability to transmit the bacteria as well.
The bacterial agent, Francisella tularensis, infects your lymphatic system, causing swollen and tender lymph nodes, fever, and general misery. Tularemia can become dangerous for children and the elderly.
13. Ross River virus and Barmah Forest virus
This last mosquito-borne infection is pertinent to travelers to Australia. The Ross River and Barmah Forest viruses, carried commonly by Aedes species of mosquitoes throughout Australia, is a major infectious agent down under.
Symptoms are generally mild, and similar to Chikungunya, the biggest complaint is a fever and malaise followed by an extended period of painful inflammation in several joints.
Fortunately, this is not a terribly dangerous bug, but not a great way to spend your time on vacation, either.
Prevention is the greatest cure
Preventing mosquito-borne illnesses involves some pretty basic, universal tactics. Whenever you find yourself in an infested area, at home or abroad, here are some ways to protect yourself from exposure:
- Use mosquito repellant both on your clothing and any exposed skin. The formula should contain DEET to be truly effective. People have also had success with some natural alternative to DEET, such as Avon Skin-So-Soft, and lemon/eucalyptus oil rubs.
- If you are outside at dawn or dusk, wear long sleeves and long pants as well.
- Avoid areas of standing water, such as rainwater collection barrels or swampy wetlands. This is mosquito “ground-zero”.
- Be sure to research travel advisories for the state or country you will be visiting or moving to. Talk to your doctor about any extra precautions, such as vaccines or medications, that might be available for you, or even required.
- If you are camping or sleeping in an open-air setting, be sure to employ mosquito nets and make sure your tent is well-sealed and has a finely meshed screen. Spray some DEET around your tent to keep mosquitoes far away. If you are able to, sleep in the breeze of a fan. Mosquitoes are weak flyers and tend to avoid breezes.
And of course, if you develop symptoms of illness after being bitten by mosquitoes, seek medical help right away.
Remember, too, that as scary as these diseases sound, they are relatively rare. Use a few precautions and some common sense, but don’t let the fear of becoming ill ruin your enthusiasm for your trip.
For more information, visit the CDC website to research mosquito-related infections and prevention.