**1. Introduction**

Conflict and war can have obvious and profound effects on the transmission and severity of infectious diseases. Although poverty is often listed as the most important external influence on disease rates, the impacts of war and conflict are also important and can lead not only to damaged public health infrastructure, displaced populations and disrupted habitats of zoonotic reservoirs and vectors, but also to the economic perturbations that increase poverty rates within affected populations [1]. Sedentary rural populations are particularly vulnerable to the disruptions of conflict due to their limited ability to adapt after the destruction or confiscation of their crops and arable land [2]. After initial losses, limited access to seeds, tools or draft animals also leads to a vicious cycle of decreasing production, resulting in increased starvation and decreased health status. This is complicated even further by dysfunctional distribution caused by lack of transportation and fuel, damaged roadways, road blocks and local violence. Malnutrition is the inevitable result of these disruptions to the food security of affected populations. Children under the age of five are the most vulnerable to nutritional deficits and thus they frequently suffer disproportionately from the effects of violence and conflict. Pregnant and breast-feeding women are also vulnerable to the effects of disrupted food supplies due to their increased nutritional needs. Increases in malnutrition in turn lead to compromised immune systems, leaving individuals susceptible to many conflict-associated infectious diseases.

Populations that are impacted by violence are often forced or choose to leave their traditional family homes to migrate to a safer environment. Public health workers have known for many years that displaced populations are particularly vulnerable to epidemics of infectious disease [3]. This increased vulnerability can be due to a variety of factors including compromised immune systems as a result of malnutrition, decreased sanitation, insufficient housing or protection from disease vectors, exposure to regional diseases to which immigrants have little or no immunity, and other factors. Thus conflict and poverty are related, and can work

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synergistically to increase disease risks in affected populations, especially those that are displaced.

Conflict can also increase disease risk in populations of warfighters (referred to as "soldiers" here even though it is acknowledged that not all warfighters are soldiers). Soldiers often deploy to regions that are endemic for diseases to which they have no previous exposure. As a result of their lack of exposures, the soldiers are often immunologically naïve to the endemic diseases of the areas to which they deploy, rendering them vulnerable to outbreaks of exotic diseases. Although modern militaries often have sophisticated immunization programs, there are no effective vaccines for many diseases of military importance, including malaria, dengue and leishmaniasis. In such situations, the soldiers must rely on other means of protection including strictly enforced hygiene, anti-vector measures, chemoprophylaxis and personal protection such as mosquito netting and repellents. Disease risk to soldiers is especially high during the initial stages of a conflict when the soldiers may live in rudimentary shelters that provide inadequate protection from vectors, vermin and the elements. Food safety, good water quality, and adequate general hygiene are particularly difficult to maintain during this phase of the conflict. As the conflict ages, the soldiers often acquire better housing and protection from the environmental hazards; however, the protracted stresses associated with war fighting, accompanied by more mundane factors such as boredom and separation from families, can also contribute to immune system dysfunctions and increased disease transmission.

Paradoxically, the impact that conflict-associated diseases have on militaries can improve the success of programs to lower the risk of acquiring those diseases. This observation does not imply in any way that wars are beneficial to public health, but only that the efforts that militaries put toward protecting their troops can improve treatment and prevention of those same diseases in other environments free of conflict or war. For instance, the impact of malaria during WWI and the need to acquire more dependable supplies of the anti-malarial quinine stimulated efforts by the U.S. military to develop cheaper synthetic substitutes like meparene and chloroquine. Similarly, the military's use of insecticidal chemicals such as DDT and BHC served as models for subsequent successful civilian programs to control the disease vectors of malaria and dengue. Also, effective vaccines are often developed initially in response to military need. Finally, one of the most effective repellents used as a personal protective measure against mosquitoes and other vectors, N,N-diethy-meta-toluamide or DEET, was developed by the U.S. Army in large part as a result of its experiences with malaria and other vector-borne diseases during WWII [4]. Such developments are direct results of the attention to the disease during military operations in endemic areas, as well as the medical and scientific expertise and relatively large sums of money available to develop disease interventions for the population of soldiers.

Many of these general conclusions about the impact of conflict on disease rates have particular significance to the disease leishmaniasis. This chapter provides a review of conflict leishma‐ niasis, especially as related to two events: (a) the civil war in Sudan and, (b) recent conflicts in the Middle East involving the militaries of the U.S. and its allies.

#### **1.1. General background on the disease and its vector**

synergistically to increase disease risks in affected populations, especially those that are

Conflict can also increase disease risk in populations of warfighters (referred to as "soldiers" here even though it is acknowledged that not all warfighters are soldiers). Soldiers often deploy to regions that are endemic for diseases to which they have no previous exposure. As a result of their lack of exposures, the soldiers are often immunologically naïve to the endemic diseases of the areas to which they deploy, rendering them vulnerable to outbreaks of exotic diseases. Although modern militaries often have sophisticated immunization programs, there are no effective vaccines for many diseases of military importance, including malaria, dengue and leishmaniasis. In such situations, the soldiers must rely on other means of protection including strictly enforced hygiene, anti-vector measures, chemoprophylaxis and personal protection such as mosquito netting and repellents. Disease risk to soldiers is especially high during the initial stages of a conflict when the soldiers may live in rudimentary shelters that provide inadequate protection from vectors, vermin and the elements. Food safety, good water quality, and adequate general hygiene are particularly difficult to maintain during this phase of the conflict. As the conflict ages, the soldiers often acquire better housing and protection from the environmental hazards; however, the protracted stresses associated with war fighting, accompanied by more mundane factors such as boredom and separation from families, can

also contribute to immune system dysfunctions and increased disease transmission.

Paradoxically, the impact that conflict-associated diseases have on militaries can improve the success of programs to lower the risk of acquiring those diseases. This observation does not imply in any way that wars are beneficial to public health, but only that the efforts that militaries put toward protecting their troops can improve treatment and prevention of those same diseases in other environments free of conflict or war. For instance, the impact of malaria during WWI and the need to acquire more dependable supplies of the anti-malarial quinine stimulated efforts by the U.S. military to develop cheaper synthetic substitutes like meparene and chloroquine. Similarly, the military's use of insecticidal chemicals such as DDT and BHC served as models for subsequent successful civilian programs to control the disease vectors of malaria and dengue. Also, effective vaccines are often developed initially in response to military need. Finally, one of the most effective repellents used as a personal protective measure against mosquitoes and other vectors, N,N-diethy-meta-toluamide or DEET, was developed by the U.S. Army in large part as a result of its experiences with malaria and other vector-borne diseases during WWII [4]. Such developments are direct results of the attention to the disease during military operations in endemic areas, as well as the medical and scientific expertise and relatively large sums of money available to develop disease interventions for the

Many of these general conclusions about the impact of conflict on disease rates have particular significance to the disease leishmaniasis. This chapter provides a review of conflict leishma‐ niasis, especially as related to two events: (a) the civil war in Sudan and, (b) recent conflicts in

the Middle East involving the militaries of the U.S. and its allies.

displaced.

148 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

population of soldiers.

Leishmaniasis is a result of a parasitic infection by any of several species of the protozoan *Leishmania.* The parasite genus is somewhat catholic in distribution, infecting up to 12 million people on all continents except Australia and Antarctica [5]. Parasites have been identified in Australia but, to date, have not infected humans, only kangaroos and wallabies [6]. The disease manifests in a variety of pathologies depending on the species of parasite and perhaps other factors, with effects ranging from mild scarring to severe disfiguration to death [7]. Localized cutaneous leishmaniasis usually affects body parts that are typically uncovered such as the face and hands. An initial papule lesion often develops into a circumscribed ulcer that may elicit little pain or itching. However, secondary infections are common. Many smaller lesions of the cutaneous form will self-heal, providing incomplete immunity for the person to further infections with the same parasite species; however, multiple lesions may occur. Diffuse cutaneous leishmaniasis may occur when lesions disseminate and this form of the disease often resembles lepromatous leprosy.

A more severe form of the disease usually associated with infections in the New World is mucocutaneous leishmaniasis. This infection often develops in the nasal septum and can result in severe mutilation of the lip, gums, tonsils, pharynx and palate. Damage may be severe enough to cause death through malnutrition and acute respiratory pneumonia.

The most severe form of the disease is visceral leishmaniasis, or kala-azar. This form is usually fatal if left untreated and most deaths from this disease are due to the visceral form. Victims progress through fevers, malaise, and weight loss that are associated with anemia, hepatome‐ galy and spleenomegaly. Secondary bacterial infections are also common and may lead to tuberculosis, pneumonia or diarrhea; these conditions contribute to the high mortality associated with this form of leishmaniasis.

The *Leishmania* parasites spend part of their development cycles in a variety of reservoirs depending on parasite species. For example, for *L. infantum,* a cause of visceral leishmaniasis, researchers believe the reservoirs are domestic dogs, jackals, foxes and perhaps certain rodents. Conversely, humans are considered to be the reservoir for another parasite associated with visceral leishmaniasis in China, *L. donovani*. [5, 8]. More complete reviews of the various forms of the disease are found in other chapters of this book.

Leishmaniasis is a vector-borne disease and the primary means of transmission from reservoir to host is via the phebotomine sand fly, though there have been reports of transmission by blood transfusion [9]. Common names associated with this insect can be misleading because they are known as 'straw mosquitoes' in some parts of their range even though they are not mosquitoes. Also, non-vector insects, such as certain midges, are sometimes known as sand flies so it is important to understand the difference between this vector and other insects. The phlebotomine sand fly is a small, delicate insect which typically flies in short hops close to the surface of the ground. Knowledge about the larval development sites is incomplete so attempts to control the disease through larval control have been frustrating. The adult sand flies are usually less than 3.5 mm in length and are covered with dense "hairs". When at rest they hold their wings in a characteristic "V" shape over their backs. Only the female sand fly takes a blood meal as the blood is essential to complete the development of egg batches. Like the male, her primary source of nutrition is carbohydrates from plant juices. The acquisition of the *Leishma‐ nia* parasite, then, is incidental to taking blood meals. The sand flies usually feed at night or in the early evening. In the New World, they are mostly encountered near forested environments, often being found near particular types of trees or tree buttresses. However, in the Old World, they are mostly associated with rodent burrows in dry or desert environments. Unlike mosquitoes, the larvae do not develop in water, though they do require a moist, warm environment in which to grow. This explains their association with rodent burrows as this environment provides the organic matter needed for nutrition of the growing larvae as well as a degree of protection from extremes in heat and moisture.

There are no vaccines or chemoprophylactic drugs to prevent leishmaniasis, so any focus on the prevention of the disease is usually associated with preventing the bite of an infective sand fly. Such efforts are obviously impeded when the public health infrastructure is disrupted, including during times of conflict.
