Leishmaniasis: Battle Scars

Aliases: It is currently known as leishmaniasis, but historically it went by the misleadingly adorable name “Jericho buttons”, due to the high number of cases near the city of Jericho.

Leishmaniasis is an old disease that has been made new, thanks to humanity’s propensity for destruction. It originates in the Old World, and while it still wreaks havoc there, it has also found new frontiers. It follows at the heels of poverty, conflict, and environmental disturbance- including urbanization, deforestation, and climate change- and afflicts some of the poorest people on the planet3.

Like many other diseases, leishmaniasis has spread by piggybacking on the effects of suffering. It usually affects the poor and malnourished, and it opportunistically infects the immunocompromised (people with weak or suppressed immune systems), such as those who are HIV positive1. Unfortunately, it has been very successful. There are an estimated 1.3 million new cases of leishmaniasis each year, and 20,000-30,000 fatalities3. The disease is now found in 90 countries, spanning the tropics, subtropics, and southern Europe, and has reached every continent except Antarctica and Australia2.

War has played a significant role in the modern resurgence of leishmaniasis. Armed conflict increases the ranks of susceptible people, by displacing and depriving them. The large-scale deployment of troops to regions where the disease is endemic (normally occurs) has also caused a jump in the number of cases1. Operation Iraqi Freedom exposed many US soldiers to the pathogen; troops reported being repeatedly bitten by sandflies. As a consequence, case numbers in the US reached levels that hadn’t been seen since WWII4. We may finally have an answer to Edwin Starr’s classic question: “War, what is it good for?” 

leishmaniasis
Good god, y’all.

Cause: Leishmaniasis is caused by more than 20 species of protozoan, aptly named Leishmania, that are transmitted by the bite of infected sandflies. This disease knows how to get around: a whopping 90 species of sandfly can transmit the pathogen, and it has about 70 animal reservoir host species, including humans3.

Consequence: There are three forms of leishmaniasis: visceral (aka kala-azar; the most serious form), cutaneous (the most common form), and mucocutaneous. Visceral leishmaniasis (VL) symptoms can be a long time coming. It can take anywhere from months to years after the infected bite for symptoms to emerge2. These include irregular fever, weight loss, enlargement of the liver and spleen, and anemia. VL is fatal, if untreated. There are an estimated 200,000-400,000 new cases a year, with 90% occurring in 6 countries: Bangledesh, Brazil, Ethiopia, India, South Sudan, and Sudan. Cutaneous leishmaniasis (CL) causes skin lesions, usually ulcers, on exposed parts of the body3, which occur within a few months of transmission2, and can leave permanent scars and disability in their wake. Over two thirds of the million or so new cases of CL each year occur in 6 countries: Afghanistan, Algeria, Brazil, Columbia, Iran, and the Syrian Arab Republic. Mucocutaneous leishmaniasis (ML) is generally a secondary infection resulting from untreated CL2. It destroys the mucous membranes of the nose, mouth, and throat. Ninety percent of ML cases occur in 3 countries: Bolivia, Brazil and Peru3.

Cure: Leishmaniasis is very treatable3. VL is most effectively treated with liposomal amphotericin (B L-AMB), however there is growing interest in combination therapy, in the hopes of reaching shorter treatment times1. There are myriad treatments for CL, ranging from topical ointments to cryotherapy4. Which is best remains a matter of debate1. All three forms of leishmaniasis can be combatted with preventative measures, including insecticide treated bed nets, sandfly control, disease surveillance, and control of reservoir hosts3.

References

  1. Antinori, S, L Schifanella, & M Corbellino. (2012). Leishmaniasis: new insights from an old and neglected disease. European Journal of Clinical Microbiology and Infectious Disease. 31: 109-118.
  1. Leishmaniasis. Centers for Disease Control and Prevention. 10 January 2013. Web. 13 March 2015.
  1. Leishmaniasis. World Health Organization. February 2015. Web.13 March 2015.
  1. Weina, PJ, RC Neafie, G Wortmann, M Polhemus, & NE Aronson. (2004). Old world leishmaniasis: an emerging infection among deployed US military and civilian workers. Clinical Infectious Diseases, 39: 1674-1680.

Image source: Creative Commons, http://commons.wikimedia.org/wiki/File:JerichoButtons.jpg

War and Disease: Half the Horsemen

War and disease are the peanut butter and jelly of destruction, together making up half of the horsemen of the Apocalypse. Wherever war goes disease is apt to follow. In fact, historically, more soldiers have died due to disease than at the hands of their human enemies. Although the advent of greater prevention and treatment techniques has quelled the epidemics of the past in recent conflicts, the relationship between combat and disease remains strong. Modern militaries have not only failed to eradicate infectious disease, they have also, much to everyone’s terror, honed the devastating power of pathogens into potential weapons of mass destruction.

Death toll

The conditions of war are ideal for the spread of disease. Training camps, barracks, and refugee camps bring together large groups of people from disparate regions, potentially harboring different infectious agents. The stress, famine and water shortages that occupy war zones along with armed forces suppress the immune systems of soldiers and civilians, leaving them more vulnerable to the attack of pathogens. The unsanitary living conditions that many are forced to endure also foster disease spread7.

Because of its rapid spread among troops, disease was responsible for the majority of deaths in combat zones until the 20th century2,4. The ratio of deaths due to disease and those caused by conflict were truly staggering, getting as high as 7:1 for American troops in the Mexican War. The first war where both armies suffered greater casualities from battle death than from disease was the Russo-Japanese war of 19044. Prior to 1918, the majority of the noncombat deaths (deaths caused by anything other than wounds sustained in combat) in the American armed forces were due to disease2. Infectious diseases, such as dysentery, cholera, typhus, malaria and smallpox, were the most common illnesses to afflict soldiers. The rampages of these epidemics had wide-ranging effects; they not only reduced the fighting ability of the troops, they also impacted the leadership of commanding officers2.

horsemen
Some things just go together.

The development of vaccines and antibiotics dramatically altered the impact of disease on society generally, including in war. In World War II, mass immunizations kept the spread of diseases such as tetanus (a major illness in WWI), and smallpox, exceptionally low compared to previous conflicts. The mass production of penicillin made bacterial illnesses, like typhus, treatable for the first time. While these improvements curtailed the mortality from the common ailments of war, infectious disease continues to afflict servicemen and women. The US forces lost 9 million man-days of active duty to malaria in WWII between 1942 and 1945, and it, along with other vector-borne diseases, continue to affect US soldiers2,5.

Disease as a weapon

The use of biological weapons, the weaponization of disease, is likely nearly as ancient as warfare itself. The Romans described attempting to introduce a man-made malady of bubonic plague and smallpox to enemy soldiers. European and American military commanders intentionally exposed Native Americans to smallpox1. And biological weapons have continued to be used in the modern era; in the 1930s and 1940s, Japanese forces used the plague and other bacterial agents against the Chinese3. In the 20th century, there were 100 confirmed cases of “illicit use of biological agents”, ranging from personal attacks to national terrorism, and as of 1995, 17 countries were suspected of developing biological weapons6.

Despite the fact that so many nations have experimented with biological weapons, there is widespread repugnance at their use. The public aversion probably reflects a major downside of biological weaponry: they are alive (or in the case of viruses, life-like). Inert arms can be targeted on a specific population, and their impact can be controlled. Biological weapons are unpredictable; there is no way to ensure that they will only affect the enemy. Disease doesn’t respect national borders, and will not limit itself to the destruction of combatants. There is no reason to assume that a weaponized pathogen wouldn’t turn on the nation that deployed it8.

All of these complications lead to the conclusion that biological weapons are a catastrophically bad idea. Most governments seem to agree with that, and international treaties, such as the 1972 Biological Weapons Convention, seek to codify that belief. Unfortunately, these agreements have not stopped several countries from continuing work on biological weapons (even some who’ve signed them). Consequently, many countries have sought preventative measures, setting up defensive research and testing programs, and extensive monitoring systems, which may also cause accidental outbreaks. While these efforts are critical in the suppression of biological weapons, we need to fight fire with fire. To stave off the threat of biological weaponry, we need to cultivate our abhorrence of it. Our greatest protection against biological weapons is our own revulsion.

References

1. Appel, JM. (2009). Is all fair in biological warfare? The controversy over genetically engineered biological weapons. Journal of Medical Ethics, 35(7): 429-432.

2. Cirillo, VJ. (2008). Two faces of death: Fatalities from disease and combat in America’s principal wars, 1775 to present. Perspectives in Biology and Medicine, 51(1): 121-133.

3. Cole, LA. (1996). The specter of biological weapons. Scientific American, December: 60-65.

4. Councell, CE. (1941). War and infectious disease. Public Health Reports, 56(12): 547-573.

5. Goldrick, BA. (2004). Emerging infections: Another hazard of war: Infectious diseases. The American Journal of Nursing, 104(12): 64-66.

6. Kortepeter, MG, & GW Parker. (1999). Potential biological weapons threats. Emerging Infectious Diseases, 5(4):523-527.

7. Peterson, RKD. (1995). Insects, disease, and military history. American Entomologist, 147-160.

8. Steinbruner, JD. (1997). Biological weapons: A plague upon all houses. Foreign Policy, 109: 85-96.

Image source: http://en.wikipedia.org/wiki/Four_Horsemen_of_the_Apocalypse