March 20, 2017
The Syrian civil war has resulted in a public health emergency marked by a rising incidence of infectious diseases, including cutaneous leishmaniasis (CL). Historically endemic in Syria, the number of CL cases has significantly increased as a consequence of the country’s deteriorating health care systems amid the current civil war. Public health officials in Syria and neighboring countries should be concerned as the influx of refugees may facilitate the spread of disease throughout the region. Effective monitoring and treatment offer the best strategy towards reducing the burden of CL among this population.
In March 2011, sectarian violence erupted in Syria resulting in one of the world’s most pressing humanitarian crises that continues to affect millions of Syrians today (1). Recent violence has exacerbated negative health outcomes not only in terms of injury and violence, but also communicable diseases. Notably, cutaneous leishmaniasis (CL), which has been historically endemic in Syria, has seen its incidence of infection increase again amid the current civil war (2).
CL presents public health officials with a unique challenge because of its prolonged treatment schedule, making compliance difficult in a setting that suffers from resource scarcity and social unrest. The current standard of care is daily injections of pentavalent antimonial drugs administered for 20 to 28 consecutive days (3). To complicate the situation, CL is a neglected tropical disease placing the disease among the ranks of other debilitating diseases that affect 1.6 billion of the world’s most disenfranchised people (4). Even though the disease disproportionately affects poor populations in endemic regions, such as the Middle East, the implications are far-reaching as CL can reach epidemic proportions if left unchecked.
The disease is not fatal, but can cause significant morbidity and reduce the quality of life. Transmitted by the female phlebotomine sandfly, parasites of the Leishmania genus are responsible for infection, which manifests itself in ulcerative lesions on the skin (3). Depending on the species of Leishmania, transmission can be zoonotic or anthroponotic (5), thus requiring different approaches to disease control depending on which species are endemic to the region.
The Health Effects of War: Risk Factors and Determinants
The combination of deteriorating health care systems, severe hunger, and a complete lack of sanitation services predisposes Syrians to suffer from infectious diseases like CL at an alarmingly high rate (6). Epidemiological bulletins from 2016 report incidence to be over 25,000 nationally, though it should be noted that not all districts have been able to report their cases each week (7). Recent developments in the conflict would suggest an even greater burden of disease, but CL monitoring efforts have been difficult amid current violence.
Despite the many risk factors for infectious disease, CL still cannot spread without the presence of a vector. The species primarily responsible for the disease in Syria is L. tropica. Unlike many other species of Leishmania, the reservoir for L. tropica is humans (6). Accordingly, the disease is “anthroponotic” and transferred between humans and sandflies without relying on an animal reservoir to continue the parasitic life cycle (5). Therefore only two populations are necessary for CL to become endemic in a region—humans and sandflies. Consequently, mass migration does not result in a decrease in infections. As long as the sandfly vector is still present, the disease follows groups of people to continue the cycle of infection.
Because the sandfly vector does not respect national borders, public health officials in Syria and neighboring countries should be alarmed. As large numbers of refugees seek asylum in neighboring countries, like Lebanon, they may continue to suffer from diseases prevalent back in Syria. The relatively long incubation period for CL ranges from approximately two to six months (8) with reported instances of incubation periods up to four years long (9). The long incubation period complicates disease control because cases could be left undetected during initial screenings (2). Treating people for CL is one of the most effective methods of prevention since humans also act as reservoirs for the disease (5), so failing to detect it early on can lead to significantly higher incidence. In fact, a recent study conducted among Syrian refugees in Lebanon showed that approximately 85% of the cases were caused by L. tropica, rather than other species more prevalent in Lebanon. Further, the study revealed that the incidence of CL in this population was significantly greater than that of Lebanon, which has a better established monitoring system (10). The risk factors identified by the team—malnutrition, inadequate housing, and poor sanitation—were just as relevant in the refugee camps as they were back in war-torn Syria.
As the incidence of CL continues to climb and new cases are reported in neighboring countries, CL has become a regional issue that extends beyond Syria’s borders. Most notably, the number of new CL cases in Lebanon underscores the severity of the outbreak over the past few years. Between 2000 and 2012, less than 6 cases of CL were reported each year. In contrast, 1,033 CL cases were reported in 2013, 998 of which were of Syrian refugees in Lebanon (11). The actual number of cases is likely much greater due to underreporting, given the barriers to health care services that refugees face. The vast majority of cases were caused by L. tropica, which causes the majority of Syrian CL cases, but the presence of other vectors—including L. major and L. infantium—and individuals infected by them could result in outbreaks of zoonotic CL due to other species outside of endemic areas (6,11).
Moving Forward: The Importance of Refugee Health
Current efforts to reduce the burden of CL in Syria have primarily consisted of vector control programs, relying on insecticides to reduce the number of phlebotomine sandflies (12). Under the auspices of the WHO, Syrian health officials also initiated the Early Warning Alert and Response System in 2012 to monitor epidemic prone diseases, including CL (7). Both of these developments are certainly steps in the right direction, but the complexity of the situation demands further action. Vector control programs should continue to remain central to the effort against CL, but the importance of effective diagnosis and treatment cannot be emphasized enough. As is the case for any infectious disease, treatment and prevention go hand in hand. Furthermore, future studies ought to consider the potential for comorbidity with other infectious diseases because of the observed increase in cholera, measles, and tuberculosis among Syrian refugees (10). Public health workers could combine treatment for CL with attention for other infections, reducing the burden of disease in their communities and preventing further infection.
A number of countries now face a critical decision regarding refugees: they can choose (1) to fully accept them and their health-related implications or (2) to deny them asylum. The nationalistic argument for limiting refugee healthcare and directing resources towards citizens is seductive, but deeply flawed. Migration is not going away and ignoring this reality does not serve national or international interests (13). CL and other diseases defy borders, affecting the health of entire regions whether refugees are accepted or not. To receive refugees and offer treatment proactively combats the spread of disease. Turning them away may delay the presence of disease, but cannot prevent it. Controlling diseases in any population, regardless of immigration status, upholds the health of all people.
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