Understanding Leishmaniasis: Causes, Symptoms, Treatment, and More

Leishmaniasis may have roots stretching back to the ancient world. Descriptions resembling the disease appear in ancient texts. Leishmania-like fossils have been discovered preserved in amber. The infection is also described in the Ebers Papyrus, a historical Egyptian medical document. 

Here’s a brief history of its discovery in more modern times.

The disease was first discovered in 1903 by a Scottish pathologist, William Boog Leishman, during an autopsy in Calcutta, India. He identified peculiar bodies in the spleen of a patient, which he initially thought were trypanosomes (another type of parasite). At the time, he named the disease ‘dum-dum fever;’ Dum dum was the town where he was stationed.

Shortly after, another British army physician, Charles Donovan, confirmed these findings independently. These organisms are now known as Leishman bodies, named after Dr. William Leishman, who initially discovered the infection.

Around the same time, a British doctor, Ronald Ross, was investigating ‘kala-azar,’ as the disease was called in India and its surrounding regions. He reported on Dr. Leishman and Dr. Donovan’s research and proposed that the pathogen was a parasite. 

Significant outbreaks have occurred throughout history, often linked to environmental changes, wars, and displacement of large numbers of people.

Leishmaniasis is a vector-borne disease with a complex epidemiology, influenced by environmental, socioeconomic, and human behavioral factors. Here’s an overview:

Geographic distribution

• Cutaneous leishmaniasis is more widespread in South America, the Mediterranean, the Middle East, Central Asia, and Africa.
• Visceral leishmaniasis is mainly found in Brazil, East Africa (Sudan, Ethiopia, Kenya), India, and Bangladesh.
• Mucocutaneous leishmaniasis is mostly seen in South America, particularly in Bolivia, Brazil, and Peru.

Notable outbreaks

According to the World Health Organization (WHO), between 600,000 to 1 million new infections occur yearly. 

Notable leishmaniasis outbreaks include: 

• 1985-1986: Sudan: 10,000 cases. This was the first report of a cutaneous leishmaniasis outbreak in South Sudan. 
• 2001-2002: Pakistan: 11,700 cases reported in the Sindh province.
• 2005-2009: Colombia.
• 2012-2013: Syria: 100,000 cases reported during an ongoing civil war.
• 2015: Syria: 64,498 cases during outbreaks in Raqqa and Palmyra provinces.
• 2017: Syria: 33,000 cases of cutaneous leishmaniasis reported.
• 2023: Syria: 14,642 cases of cutaneous leishmaniasis reported.

Source of epidemiology and outbreak data: GIDEON, a leading database for data on infectious diseases. 

Risk factors

• Environmental changes: Deforestation, urbanization, and climate change can affect sandfly habitats and breeding patterns, influencing disease spread.
• Socio-economic conditions: Poor housing, lack of sanitation, and close proximity to sandfly breeding sites increase risk.
• Human behavior: Activities like deforestation, irrigation, and urbanization can create new breeding sites for sandflies.

Leishmaniasis spreads through the bites of infected female phlebotomine sandflies. These tiny insects carry the leishmania parasites, and when they bite someone, they pass the parasites into the person’s skin.

After the leishmania parasite enters the human body through a sandfly bite, it attacks the immune cells, specifically the macrophages, which are supposed to protect us. The parasite then multiplies inside these cells. 

Depending on the type of Leishmania parasite, it can either stay near the skin (causing sores or ulcers) or spread to organs like the liver and spleen, affecting how they work. 

This invasion and growth disrupt the body’s normal functions, leading to symptoms like skin lesions, fever, or organ enlargement and making the person feel sick.

Leishmaniasis symptoms vary depending on the type of the disease:

Cutaneous leishmaniasis

The most common form, it mainly affects the skin. Symptoms include:

• Skin sores or ulcers at the bite site which may take weeks or months to appear.
• The sores can be painless but might become painful over time.

Visceral leishmaniasis (kala-azar)

This form affects internal organs. Symptoms are more severe and include:

• Fever, which can be high and persistent.
• Weight loss.
• Enlargement of the spleen and liver.
• Anemia and other blood abnormalities.
• If untreated, it can be fatal.

Mucocutaneous leishmaniasis

This type affects both the skin and mucous membranes, typically of the nose, mouth, and throat. Symptoms include:

• Skin ulcers similar to cutaneous leishmaniasis.
• Over time, lesions may spread to mucous membranes, causing tissue damage in the nose and mouth, leading to difficulty in speaking and eating.

The severity and progression of symptoms can vary based on the individual’s immune response and the specific species of the parasite.

Leishmaniasis is diagnosed through a combination of clinical evaluation and laboratory tests:

• Clinical assessment: Doctors first look at symptoms and consider the patient’s travel and exposure history, especially to regions where leishmaniasis is common.
• Laboratory tests: These are crucial for confirming the diagnosis:
• Microscopic examination: Samples from sores or tissue (like bone marrow or spleen biopsy for visceral leishmaniasis) are examined under a microscope to detect the parasite.
• Culture: The sample is cultured in a laboratory to grow the parasite for identification.
• Polymerase Chain Reaction (PCR): This test detects the genetic material of the parasite in samples.
• Serology tests: Particularly for visceral leishmaniasis, these tests detect antibodies against the parasite, indicating infection.
• Other tests: For visceral leishmaniasis, blood tests to check for anemia, low white blood cell count, and enlarged liver or spleen can support the diagnosis.

The method chosen depends on the form of leishmaniasis suspected and the resources available. Accurate diagnosis is vital for proper treatment and management of the disease.

Diagnosing leishmaniasis is challenging due to:

• Non-specific symptoms that mimic other conditions
• Limited access to specialized diagnostic tests in endemic regions
• Variability in test accuracy depending on the disease form and stage and 
• The need for skilled personnel to perform and interpret certain tests, like microscopy.

Leishmaniasis treatment varies based on the type and severity of the disease:

Cutaneous leishmaniasis

• Local therapy: Small, uncomplicated skin sores can sometimes heal on their own. Treatments for persistent or larger sores include topical medication, cryotherapy (freezing the lesion), or local injections of antiparasitic drugs.
• Systemic therapy: For more extensive or recurrent cases, oral or intravenous antiparasitic medications (like Pentavalent antimonials, Miltefosine) may be necessary.

Visceral leishmaniasis

This form requires more aggressive treatment due to its severity. Commonly used drugs include Liposomal amphotericin B, Pentavalent antimonials, and Miltefosine. Treatment is usually administered intravenously or orally over a period of several weeks.

Mucocutaneous leishmaniasis

Treatment is similar to that of visceral leishmaniasis, often requiring systemic antiparasitic therapy due to the severity and potential for disfiguring lesions.

The choice of medication depends on factors like the leishmania species, the patient’s overall health, and the drug availability and resistance patterns in the region. 

Monitoring and supportive care are also important, especially for visceral leishmaniasis, to manage complications and prevent relapse. In all cases, early diagnosis and appropriate treatment are crucial for effective management of the disease.

The treatment of leishmaniasis faces a range of significant challenges, each complicating the effective management of the disease:

• Limited drug options: There are a few effective drugs available, and many have serious side effects. This limits the choices for treatment, especially for patients with pre-existing health conditions or those who experience severe side effects.
• Drug toxicity: The most commonly used drugs, like antimonials and amphotericin B, can be highly toxic. They often cause adverse effects like kidney and liver damage, which require careful monitoring and management.
• Drug resistance: There’s an increasing concern about the parasite developing resistance to existing drugs. This is particularly problematic for visceral leishmaniasis, where treatment options are already limited. Drug resistance prolongs treatment duration and decreases its effectiveness.
• Access and cost: Many of the affected regions are impoverished, and access to healthcare is limited. The cost of medication and the need for hospitalization (for drugs administered intravenously) can be prohibitive for many patients.
• Administration challenges: Some treatments require intravenous administration, which is not always feasible in remote or resource-limited settings. This limits the ability to treat patients effectively in areas where leishmaniasis is most prevalent.
• Geographical variability: The efficacy of treatments can vary depending on the geographic region, partly due to different parasite species and strains. This necessitates region-specific treatment protocols, complicating the standardization of care.
• Extended treatment regimens: Some forms of leishmaniasis require prolonged treatment courses, which can be challenging for patients to complete, leading to issues with compliance and, consequently, treatment effectiveness.
• Co-infections and immune status: In patients with compromised immune systems, such as those with HIV/AIDS, leishmaniasis treatment is more complicated and less effective. Additionally, co-infections can complicate treatment choices and outcomes.

Addressing these challenges requires a multifaceted approach, including the development of safer, more effective, and easily administered drugs, improved diagnostic tools, and better access to healthcare services in endemic regions. 

Research into vaccine development and more effective public health strategies also play a crucial role in the broader effort to control and eventually eliminate leishmaniasis.

Preventing Leishmaniasis infections involves both individual protective measures and broader public health strategies:

Individual protective measures

Avoid sandfly bites

• Use insect repellent containing DEET, picaridin, or IR3535.
• Wear long-sleeved shirts and pants, especially from dusk to dawn when sandflies are most active.
• Sleep under insecticide-treated bed nets.
• Use air conditioning or window and door screens in endemic areas.

Environmental management

• Reduce sandfly breeding sites by clearing up waste and rubble near houses.
• Keep domestic animals away from sleeping areas, as they can be reservoirs for the parasite.

Public health strategies

Vector control

• Regularly spray insecticides to kill sandflies, especially in high-risk areas.
• Implement environmental modifications to reduce sandfly breeding and resting sites.

Surveillance and monitoring

• Actively survey and monitor Leishmaniasis cases to identify outbreaks early.
• Map areas at risk to focus prevention and control efforts effectively.

Health education and awareness

• Educate communities in endemic areas about Leishmaniasis, its transmission, and prevention methods.
• Inform travelers to endemic regions about protective measures.

Improved housing and living conditions

• Promote better housing designs that minimize the entry of sandflies.
• Improve living conditions in rural and underdeveloped areas where the disease is more prevalent.

Research and development

• Invest in the development of vaccines (still in research phases) and more effective diagnostic tools and treatments.
• Conduct studies to understand the ecology of sandflies and the parasite.

Collaboration and integration

• Integrate Leishmaniasis control programs with other vector-borne disease control programs.
• Collaborate internationally, especially in border areas and regions where the disease is endemic.

Implementing these strategies requires coordinated efforts from governments, health organizations, and communities. Effective prevention and control of Leishmaniasis not only reduces the incidence of the disease but also improves overall public health and quality of life in affected areas.

In conclusion, Leishmaniasis is a persistent threat that requires our collective efforts. This parasitic disease comes in various forms, causing various symptoms that affect well-being. 

Fortunately, it is preventable and manageable with the right measures.

Prevention strategies like vector control, bed nets, and protective clothing are crucial in reducing Leishmaniasis transmission. Public health interventions, early diagnosis, and treatment are equally vital, along with raising awareness in endemic regions. Investment in research, education, and healthcare infrastructure empowers communities to combat this disease.

Vigilance and monitoring of infected cases are essential to prevent outbreaks. Healthcare professionals, researchers, and governments must work together to track and manage cases effectively.

GIDEON is one of the most well-known and comprehensive global databases for infectious diseases. Data is refreshed daily, and the GIDEON API allows medical professionals and researchers access to a continuous stream of data. Whether your research involves quantifying data, learning about specific microbes, or testing out differential diagnosis tools– GIDEON has you covered with a program that has met standards for accessibility excellence.

Learn more about leishmaniasis and other infectious diseases on the GIDEON platform.