The Sting of The Sand Fly Essay

Admittedly, since the beginning of time, disease has played a drastic role in the history of society. It has affected economic conditions, wars, and natural disasters. The impact of any disease can be far greater than some far better known catastrophes. In 1918, an epidemic of influenza swept the globe, killing between 20 million and 40 million people. Within a few months, more than 500,000 Americans had died. This is a number far greater than the number of people killed during World War I, World War II, the Korean War, and the Vietnam War combined.

Over one quarter of the world’s population are at risk from parasitic infections, and the majority of these infections are confined to the world’s poverty belt, the tropics and sub-tropics. Low income levels are greatly associated with debilitating disease patterns. Kala Azar, Black Fever, Sand Fly Disease, and Dum Dum Fever; all different names for one fatal, flesh-eating disease, spread by the almighty bite of the vicious female sand fly. The common name for this deadly disease is Leishmaniasis.

Approximately 350 million individuals in 88 countries; including Afghanistan, Syria, Saudi Arabia, Peru, Iran, Brazil and parts of China, are at great risk of contracting Dum Dum Fever. Leishmania is a genus of Trypanosomatid protozoa, the parasite responsible for the disease Leishmaniasis. Protozoa are single-celled and considered to be the simplest of all organisms in the animal kingdom. The types of blood-sucking protozoa which cause the Sand Fly Disease are in coincidently carried by the blood-sucking sand fly. The sand fly is referred to as the disease vector, meaning that the infected protozoan is now being carried by the sand fly.

Over time, it will soon be passed on to other animals or humans, in which the protozoan will set up shop and wreak havoc. Risk factors mainly include climate change and other environmental changes, that have the potential to expand the geographic range of Leishmaniasis transmission in the future. Cases in the United States are mostly imported from other countries, by travelers or immigrants, and are more commonly found in our canine friends. It has been estimated that there are 2 million new cases of Leishmaniasis every year in the world, of which 1. 5 million are categorized as cutaneous Leishmaniasis and 0. million are visceral Leishmaniasis. Less commonly, transmission of this disease can also occur from direct transmission between dogs and from dogs to humans. Therefore, direct contact with open wounds or exudates of dogs with Leishmaniasis and contaminated objects should be avoided to prevent potential contact transmission of Leishmania. Leishmaniasis is classified as one of the most neglected diseases, based on the limited resources invested in diagnosis, treatment and control, and its strong association with poverty. Digging into this a little deeper, I will give a brief history lesson on Leishmaniasis.

Canine Leishmaniasis was first identified in Europe in 1903, and in 1940, nearly half (40%) of all dogs in Rome were determined to be positive for Leishmaniasis. Traditionally thought of as a disease only found near the Mediterranean basin, 2008 research claims new findings are evident that Leishmaniasis is currently expanding in continental climate areas of northwestern Italy, far from the recognized disease-endemic areas along the Mediterranean coasts. Cases of Leishmaniasis began appearing in North American in 2000, and Leishmania-positive foxhounds have been reported in 22 states and two provinces of Canada as of 2008.

Furthermore, on the human side of it, descriptions of conspicuous lesions have been discovered on tablets form King Ashuranipal from the 7th century BC, some of which may have been derived from even earlier texts from 1500 to 2500 BC. Muslim physicians in the 10th century AD gave detailed descriptions of what was called Balkh sore. Physicians in the Indian subcontinent would describe it as Kala-Azar. More recently, evidence of the cutaneous form of the disease was found in the Ecuador and Peru in the pre-Inca potteries depicting king lesions and deformed faces dating back to the first century AD.

Additionally, 15th and 16th century texts from the Inca period and from the Spanish colonial mention “Valley Sickness,” “Andean Sickness,” or “White Leprosy” which are likely to be Cutaneous Leishmaniasis. Following this a little further, Leishmaniasis is usually transmitted in many tropical and subtropical countries, and is found in certain parts of about 88 countries. Currently, approximately 350 million people are living in these areas. It affects as many as 12 million people worldwide, with around 2 million new cases each year.

Leishmaniasis is also found through much of the Americas from northern Argentina to southern Texas, though not in Uruguay or Chile, and has recently been shown to be spreading to north Texas. During 2004, it is estimated that around 3,400 Colombian troops, operating in the jungles near the south of the country, were infected with Leishmaniasis. Within Afghanistan, Leishmaniasis occurs commonly due to bad sanitations and waste left uncollected in the streets. Additionally, Leishmaniasis has been reported by U. S. troops stationed in Saudi Arabia and Iraq since the Gulf War of 1990.

Also, in some areas of southern Europe, Leishmaniasis is becoming an important disease which infects people with weakened immune systems. In particular, individuals with AIDS are at greater risk of this infection. Moreover, like earlier stated, Leishmaniasis is not limited to just one form, with some being more harmful than others. There are 21 species of the parasite in two different forms: Cutaneous Leishmaniasis, which affects the skin and mucus membranes and Systemic or Visceral Leishmaniasis, which affects the entire body. First off, Cutaneous Leishmaniasis is often times broken down in to localized and diffuse Leishmaniasis.

Localized Cutaneous Leishmaniasis mostly occurs in China, India, Asia, Africa, the Mediterranean Basin, and Central America. It is perhaps the least drastic type of disease caused by any of the Leishmania. Wherever the bite occurred, the host may notice an itchy bump or lesion several weeks or months after being bitten by the infected sand fly. Lymph nodes in the area of this bump may be swollen. Within several months, the bump develops a crater or ulceration in the center, with a raised, reddened ridge around it. There may be several of these lesions near each other, and they may spread into each other to form one large lesion.

On one hand, localized cutaneous Leishmaniasis will usually heal on its own but it may take as long as one year. At times, a light colored scar is left behind. On the other hand, some lesions never heal and may invade and destroy the tissue below. For example, lesions on the ears slowly invade and destroy the cartilage which supports the outer ear. Secondly, Diffuse Cutaneous Leishmaniasis occurs most often in Ethiopia, Brazil, Dominican Republic, and Venezuela. The lesions of Diffuse Cutaneous Leishmaniasis are very similar to those of Localized Cutaneous Leishmaniasis, except they are spread all over the body.

The body’s immune system fails to battle the protozoa, which are free to spread throughout. It is often said that the characteristics of these lesions, resemble those of the dread biblical disease, leprosy. Third, Mucocutaneous Leishmaniasis occurs primarily in the tropics of South America. This disease begins with the same sores in Localized Cutaneous Leishmaniasis. Sometimes these lesions heal, and when they don’t, they spread and become larger. Once in a blue moon, years after the first lesion is gone, new lesions appear in the mouth and nose, and occasionally in the area between the genitalia and the anus.

These new lesions are known to be particularly destructive and extremely painful. They erode underlying tissue and cartilage, frequently eating through the septum. If the lesions spread to the roof of the mouth and the larynx, they have been known to prevent speech. Other symptoms include fever, weight loss, and anemia. Also, there is always a large danger of bacteria infecting the already open sores and causing further problems. Finally, last but not least, this brings me to Visceral Leishmaniasis.

This occurs in India, China, the southern region of Russia, throughout Africa, the Mediterranean, and South and Central America. This is where it is frequently referred to as Kala-Azar or Dumdum fever. Kala-Azar, when translated, means, “black fever. ” The protozoa in this disease use the bloodstream to travel to the liver, spleen, lymph nodes, and bone marrow. Fever may last for as long as eight weeks, disappear, and then reappear again. Often times the lymph nodes, spleen, and liver are enlarged. Common symptoms include; weakness, fatigue, loss of appetite, diarrhea, and weight loss.

Furthermore, diagnosis for each of these types of Leishmaniasis involves taking a scraping from a lesion and examining it under a microscope, to determine which parasite is causing the disease. Other methods that have been used include; culturing a sample piece of tissue in a laboratory to allow the protozoa to multiply for easier microscopic identification, injecting a mouse or hamster with a solution made of scrapings from a patient’s lesion to see if the animal develops a Leishmaniasis-like disease, and demonstrating the presence in macrophages of the characteristic-appearing protozoan.

Moreover, for certain forms of Leishmaniasis, a skin test may be used. In this test, a solution containing a small bit of the protozoan antigen is injected or scratched into a patient’s skin. In a positive reaction, cells from the immune system will race to this spot, causing a characteristic skin lesion. However, not all forms of Leishmaniasis cause a positive skin test. Granted, the prognosis for Leishmaniasis is quite variable, and depends on the specific strain of infecting protozoan, as well as the individual patient’s immune system response to infection.

Localized Cutaneous Leishmaniasis may not require any treatment. Although it may take many months, these lesions usually will completely heal by themselves. Only rarely do these lesions fail to heal and become more destructive. In rare cases Cutaneous Leishmaniasis may smolder on for years without treatment, ultimately causing death when the large, open lesions become infected with bacteria. Oddly enough, Mucocutaneous Leishmaniasis is often relatively resistant to treatment. Untreated Visceral Leishmaniasis has a 90% death rate, but only a 10% death rate with treatment.

The aim of therapy is to eliminate the parasite and definitively cure the patient. Unfortunately, this is the exception rather than the rule, when it comes to our canine friends, as reoccurrence rates are very high. It has be stated that infected dogs have 75% probability of surviving at least four years if they are given a course of 21 to 42 days of meglumine antimonite and subsequent treatments at ever recurrence. Consequently, often times euthanasia of infected dogs is performed in order to prevent the transmission of the disease.

In addition, prevention of Leishmaniasis involves protection against sand fly bites. Insect repellents used around homes, on clothing, on skin, and on bed nets can be effective measures. Reducing the population of sand flies is also an important preventive measure. In areas where Leishmaniasis is very common, recommendations include; clearing the land of trees and brush for at least 300 meters around all villages, and regularly spraying the area with insecticides. Because rodents often carry the protozoan which causes Leishmaniasis, careful rodent control should be practiced.

Canines, which also carry the protozoan, can be given a simple blood test and then either treated or put to sleep. All in all, Leishmaniasis is just one of the many dangerous diseases throughout the world. Disease is everywhere we look and everywhere we don’t! Like danger, this “pain in the ass” is lurking in the shadows of the night, right behind us in every corner. Quietly, awaiting for its chance to leap on us and attack our body’s immune system. Though, if certain precautions are taken, we can greatly minimize the risk and spread of disease.

Millions of people each year have perished as a result of one of any number of seemingly unstoppable diseases. Throughout history, mankind has suffered the crippling blows of a ravaging disease brought on by any number of target factors, ranging from animals to one single human host. I guess as humans we just need to be cautious and deal with it, as disease will continue to reluctantly grow and wreak havoc on all of man kind, as it did the previous million millennia.