Leishmaniasis: The Parasitic Infection That "Flies"

Most of the infections I have presented to all of you have been fairly rare conditions.  Transmissions have included being in contact with infected sharp objects and ingesting contaminated food or material.  However, today I came across an article, few years old, talking about an infections that was becoming a problem in the world.  This emerging infection is called leishmaniasis and what I find most unusual about this infection is that it is transmitted by sand flies.
At least in my opinion, I only hear about mosquitoes being the main vector of certain diseases, but hearing that a fly can transmit infections sparks my curiosity.  I am sure there are many species of flies that transmit diseases and I may not know about, but nevertheless, it is useful to know about the many types of insect vectors certain parasitic infections may use to spread. This infection strikes me as an unusual infection that I believe everyone should know about, especially when traveling.

General Description:
Leishmaniasis is a parasitic infection caused by a protozoa from the genus Leishmania.  The main areas of infection are the skin and visceral organs, and this leads to the different types of leishmaniasis infection.  This infection is transmitted by a bite from an infected female phlebotomine sand fly.  There is a presence of this infection in almost all the continents, primarily in the tropics and subtropics.  Symptoms begin to show in a few weeks to months and some cure themselves while other cases need medical treatment.

Locations:
This infection is spread throughout the globe, affecting about 90 countries in tropic and subtropic regions.  It is more common in rural areas and depends on the population of sand flies in the area.  Some specific areas include Africa, Asia, the Middle East, Mexico, and some parts of South America.  There are a few cases in North America, specifically in the United States.

Infection Method:
Infection begins with a sand fly biting a human host and promastigotes, which can be seen as larvae, become trapped in the immune cells of the body.  These larvae begin to transform and become the adult parasites, infecting other surrounding tissues.  The type and severity of the infection depends on the area the parasite infects and the host.  Then, a new, uninfected sand fly bites onto an infected human and now more sand flies become carriers.  This is the way the infection cycles through sand flies and humans.

Life cycle of leishmaniasis.

Symptoms:
Symptoms range from no pain at all to life threatening conditions.  There are two main types of leishmaniasis infection: cutaneous and visceral leishmaniasis.  Cutaneous leishmaniasis is when the skin becomes infected with sores.  These sores begin to appear in the infected area within a few weeks or months and can change appearance as well; becoming more of a nodule shape.  Visceral leishmaniasis causes more serious symptoms than cutaneous.  

Cutaneous leishmaniasis skin sore.

The parasite infects internal organs like the liver, spleen, and bone marrow and the symptoms begin to show in a few months.  Symptoms include:

• weight loss
• swelling of the infected organs
• fever
• anemia

There is also a third type of leishmaniasis, mucosal leishmaniasis, however this form is uncommon and there has only been a few cases in Latin America.  In this form, the infection occurs in the mouth, nose, or throat and usually is caused by already having cutaneous leishmaniasis and not treating it properly.

Treatment:

The infection is diagnosed with simple laboratory tests.  However, tests and treatments need to be individualized.  The treatment that an infected person will receive depends on the type of leishmaniasis, the health of the patient, and the species of protozoa that caused the infection.  Cutaneous leishmaniasis can heal on its own, but can take months and leave scars.  It is important to also make sure that mucosal leishmaniasis will not occur, since this form begins to show symptoms months after cutaneous leishmaniasis.  Visceral leishmaniasis needs to be treated quickly since most advanced cases are fatal.

Final Thoughts:

I find this infection to be particularly interesting.  As I mentioned earlier, this infection is transmitted by a sand fly.  This fly does bite like a mosquito, but most people do not associate flies with carrying parasitic infections.  The scary thing is that this fly is present in most of the world, which is why this infection is so widespread.  The most unusual aspect of this infection is the pattern of transmission.  The fly bites a person, the parasite grows and spreads, then another fly bites an infected person and the parasite moves to the fly to restart the cycle.  The protozoa needs both vectors to reproduce, and in some cases it is recommended to prevent more contact with other sand flies if you are infected.

The symptoms of this infection should not be taken lightly.  If traveling to any part of the world where sand flies are present, it would be best to take insect repellent and cover your body appropriately.  If you are camping, backpacking, or hiking, you can take the tiny, portable bug net hoods you can buy at any outdoor store or online.  Personally, I took one on a camping trip and they work perfectly!  These are great if you do not want to wear repellent or wear too many layers of clothes.

As with any other infection, be cautious about the environment you are in.  Insects are an abundant vector for parasitic infections and should not be taken lightly.  Leishmaniasis is not much of a rare infection as people may think.  Remember that if bitten by a sand fly and you are in an area where Leishmaniasis may be prevalent, pay attention to symptoms.  These symptoms begin to show in a few weeks and if you see sores on your skin, then see a doctor immediately.  If the Leishmaniasis infection can be diagnosed early, then you will not have to go through the troubles of having skin problems.  Also, if you suspect that you or someone may be infected, get a full diagnosis to make sure you do not have visceral or mucosal leishmaniasis. 

I hope you enjoyed and found this information useful!  Leave a comment or recommendation for any future posts.  I am always excited to learn about new unusual parasitic infections!

References:

https://rarediseases.info.nih.gov/diseases/6881/leishmaniasis

https://www.cdc.gov/parasites/leishmaniasis/

https://www.livescience.com/56883-parasitic-infection-leishmaniasis-united-states.html