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Biometrics & Vectors

Medical entomology &biometrical modeling tools

Interactive computational and modeling tools crafted for researchers, vector control program managers, and public health entomology scholars.

04Anopheles Species
HWEχ² Test & kdr Alleles
100%WHO SOPs & Standards

05 — Entomology & Resistance

Vector identification explorer& WHO bioassay simulator

Interactive tools for anopheline species identification and standardized WHO bioassay susceptibility modeling.

Gambiae Complex

Anopheles gambiae s.s.

Primary dominant malaria vector in Sub-Saharan Africa

Behavior:Nocturnal biting, highly anthropophilic and endophagic/endophilic
Larval habitats:Temporary, sunlit, shallow freshwater breeding sites (rain pools, tyre tracks)
Resistance mechanisms:kdr (L1014F/S), overexpression of P450 cytochromes (CYP6P3, CYP6M2)
High resistance to standard pyrethroids documented across Benin
Gambiae Complex (formerly M form)

Anopheles coluzzii

Dominant vector across urban, peri-urban, and agricultural rice irrigation schemes

Behavior:Nocturnal biting, sustaining high population densities year-round
Larval habitats:Permanent and semi-permanent water bodies, urban ditches, irrigated rice fields
Resistance mechanisms:kdr and ace-1 (G119S), broad-spectrum metabolic resistance
Exceptional ecological adaptation to anthropogenic polluted water
Funestus Group

Anopheles funestus

Critical dry-season vector extending annual malaria transmission periods

Behavior:Late-night biting, strongly endophilic and anthropophilic
Larval habitats:Large, permanent, semi-shaded water collections with emergent vegetation (marshes)
Resistance mechanisms:Dominant metabolic resistance mediated by CYP6P9a/b duplicated genes
Extremely high vectorial capacity in rural and lakeside environments
Emerging Invasive Vector

Anopheles stephensi

Asian urban vector rapidly spreading across East and West Africa

Behavior:Plastic opportunistic biting behavior, competent for both P. falciparum & P. vivax
Larval habitats:Urban man-made water containers, overhead tanks, concrete basins, construction sites
Resistance mechanisms:Multiple cross-resistance to organophosphates, carbamates, and pyrethroids
Critical public health threat under high-priority WHO surveillance
WHO Tube Bioassay Parameters
65%
Standard WHO Interpretation
Confirmed Resistance
Raw Mortality76.0%
Control Mortality4.0%
Corrected Mortality (Abbott)75.0%
0%90% (Resistance)98% (Susceptible)100%
Operational Recommendation:

Observed mortality is strictly below 90%. Confirmed resistance is established for this insecticide. It is recommended to conduct synergist bioassays (PBO) and molecular characterization of kdr and P450 markers.

06 — Population Genetics & Markers

Allele frequency calculator& Hardy-Weinberg equilibrium

Interactive population genetics model to analyze evolutionary dynamics of resistance markers (<em>kdr</em> L1014F/S, <em>ace-1</em> G119S) in Anopheles vectors.

Entomological Sample Parameters
Susceptible Phenotype
Carriers of R Allele
High Resistance
0.40 (Strong Selection Pressure)
Frequency Statistics
HWE Equilibrium Verified
Total Sample Size (N)100
Allele S Frequency (p)0.310
Allele R Frequency (q)0.690
GenotypeObserved (O)Expected HWE (E)Partial χ²
SS129.610.59
RS3842.780.53
RR5047.610.12
Total χ² (1 df)1.24 (Not significant, p > 0.05)
Genetic Diagnosis:

Resistance allele <em>R</em> frequency is <strong>69.0%</strong>. The vector population adheres to Hardy-Weinberg equilibrium (χ² = 1.24 < 3.84). The allele is advancing toward fixation under intense insecticide selection pressure.

07 — Methodology & Biostatistics

Sample size calculator& statistical power (WHO Bioassays)

Biometric tool to calculate required mosquito sample sizes in bioassay protocols, WHO cone tests, and experimental hut residual efficacy monitoring.

Comparative Study Parameters
%
%
Recommended Sizing
Power 80% Validated
Required Sample / Arm (n)32Mosquitoes per arm
Total Sample Size (2n)64For both comparison groups
Recommended WHO Tubes42 tubes / arm (25 mosq.)
📐 Fleiss biometric formula with continuity correction:

n = [Zα/2 · √(2p̄(1-p̄)) + Zβ · √(p₁(1-p₁) + p₂(1-p₂))]² / (p₁ - p₂)²

Operational Protocol Plan:

To detect a mortality difference of <strong>35.0%</strong> (40% → 75%), expose a minimum of <strong>32 mosquitoes</strong> per experimental arm (rounded to <strong>2 tubes of 25</strong> mosquitoes per arm, 100 total with controls).

04 — Prevention Tools & LLINs

Comparative matrix ofnext-generation mosquito nets

Comparative analysis of long-lasting insecticidal nets (LLINs): modes of action, efficacy against multi-resistant vectors, and WHO prequalification status.

Standard

Standard LLINs (Pyrethroids Only)

Deltamethrin 55 mg/m² or Alphacypermethrin 200 mg/m²
🔬 Mode of action:

Blocks voltage-gated sodium channels (axonal hyperexcitation and mortality via knockdown effect).

🎯 Target resistance:

Effective only against fully susceptible populations (Kisumu). Efficacy compromised in kdr areas.

🌍 Context & Deployment in Benin:

Phased out from mass distribution campaigns in Benin due to high prevalence of kdr L1014F (>80%).

Field efficacyLow (< 50% mortality in kdr zones)
Durability3 years / 20 standard washes
Synergist (PBO)

PBO Synergist Nets (Pyrethroid + Synergist)

Permethrin or Deltamethrin + Piperonyl Butoxide (PBO) 10 g/kg
🔬 Mode of action:

PBO inhibits insect Cytochrome P450 enzymes, restoring susceptibility to pyrethroids.

🎯 Target resistance:

Overcomes metabolic resistance driven by overexpression of CYP6P3, CYP6M2 and CYP6P9.

🌍 Context & Deployment in Benin:

Successfully deployed in Zou and Collines departments during nationwide mass distribution campaigns.

Field efficacyMedium to High (65% - 85% mortality)
Durability3 years (Faster PBO degradation after 15 washes)
Dual-Active (Chlorfenapyr)

Interceptor G2 (Dual-Active Breakthrough Net)

Alphacypermethrin 100 mg/m² + Chlorfenapyr 200 mg/m² (Pyrrole)
🔬 Mode of action:

Pro-insecticide activated in vivo: uncouples oxidative phosphorylation in mitochondria (ATP disruption).

🎯 Target resistance:

No cross-resistance with pyrethroids, carbamates or organophosphates.

🌍 Context & Deployment in Benin:

Demonstrated superiority in Benin (CREC / LSHTM) with significant reduction in clinical malaria incidence.

Field efficacyVery High (> 90% hut mortality)
Durability3 years / Proven Phase III durability
Dual-Active (Pyriproxyfen)

Royal Guard (Pyrethroid + IGR)

Alphacypermethrin 225 mg/m² + Pyriproxyfen 225 mg/m² (Juvenile hormone mimic)
🔬 Mode of action:

Dual-action: adult knockdown coupled with irreversible sterilization of surviving female mosquitoes.

🎯 Target resistance:

Drastic reduction in vector fecundity, egg hatching rate, and lifespan of resistant vectors.

🌍 Context & Deployment in Benin:

Evaluated in Covè and Akron experimental hut stations for multi-generational resistance management.

Field efficacyHigh (Mortality + Sterility > 80%)
Durability3 years / 20 validated washes

12 — Health Economics & Policy

Cost-effectiveness modelerfor vector control strategies

Health-economic model to evaluate unit cost per person protected and cost per malaria case averted across technological interventions in resistance zones.

Health District Parameters
e.g. 150,000 residents
Cases per 1,000 persons / year
85% of population covered
Economic & Health Impact Summary
Highly Cost-Effective Strategy
Estimated Annual Budget187 000 $Total programmatic cost
Malaria Cases Averted23 100Clinical cases prevented / year
Cost / Case Averted8.10 $Cost-effectiveness ratio
Decision-Maker Policy Brief:

Deploying Chlorfenapyr Dual-Active LLINs (Interceptor G2) averts approximately 23,100 clinical malaria cases annually in a district of 150,000 residents, delivering an outstanding unit cost of $8.10 per case averted (well below WHO threshold benchmarks).

Contact

A mission, a consultation,a partnership?

Direct contact form, calendar booking, full contact details, and frequently asked questions are available on the dedicated page.

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