A vector-borne, protozoan parasitic disease, Leishmaniasis is transmitted by the bite of more than 70 different infected phlebotomine sand fly species carrying any of over 20 Leishmanial parasitic variants.8 Additional reservoirs include rodents, canines, and humans. 8 It is prevalent in over 90 countries, tropical and subtropical, throughout the Middle East, North Africa, Central and South America, Southern Europe, and the Indian subcontinent (see Table 1). 8Annually there are 900,000-1,300,000 new cases of Leishmaniasis with 20,000-30,000 cases resulting in death. 8
Three main types of Leishmaniasis:
Cutaneous Leishmaniasis
• The most common form characterized either by silent infection or by painless or painful skin sores, ulcers, and swollen glands (see Figure 1).6
• Incubation period is within two weeks to several months following the initial bite. 7
• 700,000 to 1,200,000 new cases annually. 8
• Treatments individualized with most cases healing spontaneously and resulting in scarring. 3
Visceral Leishmaniasis (Kala-Azar)
• May be life threatening and is characterized by silent infection or infection of the bone marrow, spleen, and liver.6
• Symptoms include swelling of the liver and spleen, weight loss, fever, abnormal blood tests, anemia etc. 6
• Incubation period is within three to eight months following the initial bite. 7
• 200,000 to 400,000 new cases annually. 8
• Untreated, more than 95% of cases are fatal. 8
• Individualized treatment with healing time ranging from 3-18 months. 8
• HIV-Leishmanial coinfection experience disease at maximum clinical level, with higher rates of mortality and relapse. Prevalence is highest in India, Ethiopia, and Brazil. 8
Mucocutaneous Leishmaniasis
• Results from serious cutaneous infection and is characterized by sores in the mucosal membranes. 6
• Incubation period is within one to three months following the initial bite, but may manifest years after the initial cutaneous infection. 7
Diagnosis
• Tissue specimens from cutaneous sores or bone marrow (visceral) analyzed for Leishmanial parasite. 6
• Blood tests examined for blood counts and antibodies. 6
Transmission Patterns
• Seasonal outbreaks from June to October in the Mediterranean region, with vector density at 97%. 2
• Sandfly species are most active during night time hours. 2
• For transmission cycle, see Figure 2
Populations at Risk
• Rural populations
• All ages at risk during epidemics or in areas that are nonendemic, but particularly ages 1-4 in generally endemic areas. 7
• Soldiers, ecotourists, missionaries, outdoor researchers, etc. 6
• Refugee populations. 1
• HIV-positive patients. 7
Risk Factors
• Socioeconomic status
o Increased risk with poverty, unsanitary conditions, crowding, and poor housing8
• Malnutrition
o Deficiency in vitamin A, protein, iron, etc. increase visceral incidence. 8
• Mobility
o Migrants that lack immunity moving into endemic areas have an increased risk8
• Environmental
o Deforestation and Urbanization increase incidence of Leishmaniasis. 8
• Climate change
o Reservoir and vector distribution influenced by changes in humidity, rainfall, and temperature
o Increases in temperature due to global warming have triggered an increase in cases. 2
o Migration due to climate change (floods, droughts, etc.) results in overcrowding, poor nutrition, and unsanitary conditions which spark increased incidence. 8
Recent Outbreaks
Recent outbreaks in refugee populations are attributed to sanitation issues, dirty water, lack of nutrition and inadequate housing in connection with appropriate climate and lack of health care. 1
Syria
• In 2013, about 41,000 new cases of cutaneous Leishmaniasis were documented within areas not endemic to Leishmaniasis. 1
Lebanon
• An alarming emergence of 1,033 cases in 2013, a majority of which occurred in Syrian Refugees. Prior to 2013, only 6 cases were documented in Lebanon from 2000-2012. 1
Sudan
• In 2012, an epidemic of 28,300 new cases resulting in 900 deaths. 9
Afghanistan
Over 25,000 cases emerged in 2015, with 10,000 in Kabul alone. 5
Prevention
• Currently no successful vaccine exists. 6
• Preventative measures include the use of insecticides (particularly those containing pyrethroid) and repellants outdoors and indoors, the use of bed nets (treated or untreated), reducing exposed skin, remaining indoors during most active hours for sandflies, and treating canines with insecticides. 6
• Remain indoors with air-conditioning, to create environments not ideal for sandflies. 6
• To prevent transmission from infected persons, netting is used around the patient
• In HIV Leishmaniasis coinfected individuals, survival is increased and relapse decreased through the use of antiretroviral drugs. 8
• Treatments vary depending on severity, form of disease, and parasitic strain. 8
Outbreak Response
• Identify the vector and Leishmanial species responsible for the outbreak, estimate extent and confirm incidence rates through testing. 4
• Due to longer incubation periods, identify any migration patterns to determine possible transmission where cases are not yet clinically identified. 4
• Determine treatment services availability and ensure adequate treatment supplies are available. 4
• Report cases accurately to provide better surveillance and data. 4
Preparation
• Funds should be allocated and ready for use during outbreaks. 4
• Ensure the necessary supplies and tools are minimally stocked during peak seasons in centers to allow for early treatment and reduce severity of cases and hospitalizations. 4
• Strengthen surveillance systems in place to identify endemic thresholds. 4
• Educate and train healthcare providers on treatment and the public on signs and symptoms. 4
• Utilize various methods to control vectors and reduce outbreaks
• Improve sanitation, water quality, and waste disposal to reduce risk of disease. 1
• When applicable, provide travel advisories to areas with Leishmanial epidemic outbreaks