WorldLeish7 Conference: Caratgena, Colombia, August 2022

WorldLeish7, the 7th World Congress on Leishmaniasis, was held in Cartagena, Colombia in August 2022. Leishmaniasis is a parasitic disease transmitted by sandflies, affecting 12-15 million people annually across 98 countries. The congress brought together researchers, clinicians, public health officials, and policymakers to share advances in diagnosis, treatment, epidemiology, and control of this neglected tropical disease.

Key Themes and Research Presentations

The conference covered six major tracks: parasite biology and genomics, vector biology and control, immunology and vaccine development, clinical management and drug development, epidemiology and surveillance, and public health policy. Notable presentations included updates on the leishmaniasis vaccine trials (several candidates in Phase II and III trials), new oral treatment regimens (including fexinidazole and miltefosine combinations), and the impact of climate change on sandfly vector distribution—with models predicting expansion into southern Europe and North America as temperatures rise.

# Climate change and vector distribution model (conceptual)
def estimate_risk_shift(temperature_rise: float, current_range: list) -> dict:
    # Simplified model: sandflies expand ~50km per 0.5°C warming
    expansion_km = temperature_rise * 100  # 100 km per °C
    return {
        "temperature_rise": temperature_rise,
        "range_expansion_km": expansion_km,
        "new_regions_at_risk": expansion_km > 200,
        "recommendation": "Enhanced surveillance" if expansion_km > 200
                          else "Current surveillance adequate"
    }

for delta in [0.5, 1.0, 1.5, 2.0]:
    result = estimate_risk_shift(delta, [])
    print(f"+{delta}°C: {result['range_expansion_km']}km expansion → {result['recommendation']}")

Advances in Diagnosis and Treatment

Rapid diagnostic tests (RDTs) based on recombinant antigen rK39 continue to improve, with new multiplex RDTs that distinguish between visceral and cutaneous leishmaniasis in field settings. Loop-mediated isothermal amplification (LAMP) assays for point-of-care molecular diagnosis were demonstrated, achieving 95% sensitivity and 98% specificity in rural health centers without laboratory infrastructure. On the treatment front, thermotherapy (localized heat application) for cutaneous leishmaniasis showed cure rates comparable to pentavalent antimonials with fewer side effects, and liposomal amphotericin B remains the WHO-recommended first-line treatment for visceral leishmaniasis in East Africa, with newer formulations reducing treatment duration from 28 to 10 days.

Surveillance and Elimination Programs

The WHO’s roadmap for neglected tropical diseases (2021-2030) targets leishmaniasis elimination as a public health problem in the Indian subcontinent and East Africa by 2030. Countries like Bangladesh and Nepal have reduced visceral leishmaniasis incidence by over 90% through indoor residual spraying, insecticide-treated nets, and active case finding with rapid diagnostic tests. Challenges remain in conflict-affected regions of East Africa (South Sudan, Somalia, Ethiopia) where health systems are disrupted, and in the Amazon basin where sylvatic transmission cycles make vector control impractical. The conference emphasized the need for integrated control approaches combining vector control, active surveillance, accessible treatment, and community engagement tailored to local epidemiological contexts.

WorldLeish7 Conference Outcomes and Resolutions

The conference concluded with the Cartagena Declaration, committing signatory nations to strengthen leishmaniasis surveillance, improve access to diagnosis and treatment, and support research into new tools. Key targets included: reducing visceral leishmaniasis case fatality rates below 3%, achieving 100% reporting completeness from endemic districts, and ensuring universal access to WHO-recommended diagnostics and treatments by 2025. The declaration also emphasized the need for pediatric formulations of leishmaniasis drugs (current treatments are primarily tested in adults), integration of leishmaniasis surveillance into existing health information systems, and cross-border collaboration in regions where leishmaniasis does not respect national boundaries, particularly in the Horn of Africa and the Amazon basin. The next WorldLeish congress (WorldLeish8) was scheduled to be held in Addis Ababa, Ethiopia, bringing the conference to the continent most affected by visceral leishmaniasis for the first time.

# Modeling elimination targets
def elimination_progress(current_cases, target_cfr, year):
    years_remaining = 2030 - year
    annual_reduction_needed = (current_cases / (1 + years_remaining * 0.1)) / 100
    return {
        "year": year,
        "annual_target": int(annual_reduction_needed),
        "cfr_target": target_cfr,
        "on_track": annual_reduction_needed > 0
    }
for y in range(2022, 2031):
    print(elimination_progress(50000, 0.03, y))

def estimate_treatment_access(current_coverage, target, annual_increase):
    years = 0
    while current_coverage < target:
        current_coverage += annual_increase
        years += 1
    return years
print(f"Years to reach 100% coverage: {estimate_treatment_access(0.65, 1.0, 0.05)}")

Research Priorities Identified at WorldLeish7

The conference identified five priority research areas. First, development of a pan-species vaccine targeting antigens conserved across all Leishmania species—current vaccine candidates target specific species (L. donovani for visceral, L. major for cutaneous). Second, shorter, safer treatment regimens, including combination therapies that reduce treatment duration from 28 days to 10 days and oral alternatives to injectable drugs. Third, point-of-care diagnostics that distinguish between active infection and past exposure (current serological tests cannot differentiate, leading to unnecessary treatment in endemic areas). Fourth, understanding the role of the microbiome in disease progression—emerging evidence suggests gut and skin microbiota influence sandfly attraction and host susceptibility. Fifth, climate change modeling to predict shifting disease burden as sandfly habitats expand into previously unaffected regions at higher altitudes and latitudes.

def predict_burden(temp_rise, current_cases):
    expansion = temp_rise * 0.15
    return int(current_cases * (1 + expansion))
for t in [0.5, 1.0, 1.5, 2.0]:
    print(f"+{t}C: {predict_burden(t, 50000):,} cases")