Gh152 blood capacity calculation fix (#153)

Everyone turning 20 now has the same blood capacity whether they are sick or not when they turn 20, the capacity is capped at adult blood capacity (max kid capacity was slightly higher than adult capacity).

Author: stitova-idm

Eradication/SusceptibilityMalaria.cpp

@@ -228,28 +228,9 @@ namespace Kernel
     void SusceptibilityMalaria::Initialize(float _age, float immmod, float riskmod)
     {
         SusceptibilityVector::Initialize(_age, immmod, riskmod);
-
-        // how many RBC's a person should have determined by age
-        if (_age > (20 * DAYSPERYEAR))
-        {
-            // This initializes the daily production of red blood cells for adults to maintain standard equilibrium RBC concentrations given RBC lifetime
-            // N.B. Heavily caveated, because not all adults are same size.  However, this keeps consistent equilibrium RBC densities, allowing study of anemia, etc...
-            m_RBCproduction = ADULT_RBC_PRODUCTION;// 2.0*10^11 (RBCs/day)*(120 days) = 2.4x10^13 RBCs ~= 5 liters * 5x10^6 RBCs/microliter
-
-            // This equation tracks the blood volume separately from the equilibrium number of RBCs, allowing for non-constant RBC concentration.
-            // m_inv_microliters_blood is 1/(microliters of blood in body)--this allows easy calculation of pathogen densities from pathogen numbers
-            m_inv_microliters_blood = float(1 / ( (0.225 * (7300/DAYSPERYEAR) + 0.5) * 1e6 )); // 5 liters
-        }
-        else
-        {
-            // Initializes daily production of red blood cells for children to grow linearly from INFANT_RBC_PRODUCTION to ADULT_RBC_PRODUCTION by age 20
-            // Only approximate due to linear increase in blood volume from 0.5 to 5 liters from birth to age 20 years.  Non-linear growth model might be better...
-            m_RBCproduction = int64_t(INFANT_RBC_PRODUCTION + (_age * 0.000137) * (ADULT_RBC_PRODUCTION - INFANT_RBC_PRODUCTION)); //*.000137==/7300 (linear growth to age 20)
-            m_inv_microliters_blood = float(1 / ( (0.225 * (_age/DAYSPERYEAR) + 0.5 ) * 1e6)); // linear growth from 0.5 liters at birth to 5 liters at age 20
-        }
-
-        m_RBCcapacity = m_RBCproduction * AVERAGE_RBC_LIFESPAN;  // Health equilibrium of RBC is production*lifetime.  This is the total number of RBC per human
-        m_RBC         = m_RBCcapacity;
+        
+        recalculateBloodCapacity( _age );
+        m_RBC = m_RBCcapacity; // initial m_RBC is at capacity
 
         // Set up variable pyrogenic thresholds + fever killing rates
         m_ind_pyrogenic_threshold = SusceptibilityMalariaConfig::pyrogenic_threshold;
@@ -330,11 +311,15 @@ namespace Kernel
 
     void SusceptibilityMalaria::Update(float dt)
     {
-        release_assert( params() );
+        // dt = 0.125 when infected, 1.0 otherwise
+        release_assert(params());
 
         age += dt; // age in days
         m_age_dependent_biting_risk = BitingRiskAgeFactor(age);
-        recalculateBloodCapacity(age);
+        if(age < (20 * DAYSPERYEAR + dt)) // recalculate < 20 every time step and then once when they turn 20
+        {
+            recalculateBloodCapacity(age);
+        }
 
         // Red blood cell dynamics
         if (SusceptibilityMalariaConfig::erythropoiesis_anemia_effect > 0)
@@ -569,28 +554,27 @@ namespace Kernel
     void SusceptibilityMalaria::recalculateBloodCapacity( float _age )
     {
         // How many RBCs a person should have determined by age.
-        // This sets the daily production of red blood cells for adults to maintain 
-        // standard equilibrium RBC concentrations given RBC lifetime
-        if ( _age > (20 * DAYSPERYEAR) )
+        // Sets daily production of red blood cells for people to set their equilibrium RBC concentrations and blood volume given an RBC lifetime
+        // Only approximate due to linear increase in blood volume from 0.5 to 5 liters with age, a better growth model would be nonlinear
+        if (_age >= 20 * DAYSPERYEAR) // 20 years = 7300 days
         {
-            // Update adults every year.  TODO: this presumes DAYSPERYEAR is a multiple of dt
-            if ( int(_age) % DAYSPERYEAR == 0 )
-            {
-                // 2.0*10^11 (RBCs/day)*(120 days)=2.4x10^13 RBCs ~= 5 liters * 5x10^6 RBCs/microliter
-                m_RBCproduction         = ADULT_RBC_PRODUCTION;
-                m_inv_microliters_blood = float(1 / ( (0.225 * (7300/DAYSPERYEAR) + 0.5) * 1e6 )); 
-                m_RBCcapacity           = m_RBCproduction * AVERAGE_RBC_LIFESPAN; // Health equilibrium of RBC is production*lifetime
-            }
+            // This initializes the daily production of red blood cells for adults to maintain standard equilibrium RBC concentrations given RBC lifetime
+            // N.B. Heavily caveated, because not all adults are same size.  However, this keeps consistent equilibrium RBC densities, allowing study of anemia, etc...
+            m_RBCproduction = ADULT_RBC_PRODUCTION;
+            m_inv_microliters_blood = float( 1 / ( ( 0.225 * ( 7300 / DAYSPERYEAR ) + 0.5 ) * 1e6 ) );// adult blood volume 5 liters
         }
         else
-        {
-            // Update children every day.
-            // Sets daily production of red blood cells for children to set their equilibrium RBC concentrations and blood volume given an RBC lifetime
-            // Only approximate due to linear increase in blood volume from 0.5 to 5 liters with age, a better growth model would be nonlinear
-            m_RBCproduction         = int64_t(INFANT_RBC_PRODUCTION + (_age * .000137) * (ADULT_RBC_PRODUCTION - INFANT_RBC_PRODUCTION)); //*.000137==/(20*DAYSPERYEAR)
-            m_inv_microliters_blood = float(1 / ( (0.225 * (_age/DAYSPERYEAR) + 0.5 ) * 1e6 )); 
-            m_RBCcapacity           = m_RBCproduction * AVERAGE_RBC_LIFESPAN; // Health equilibrium of RBC is production*lifetime
+        {   
+            // linear growth from 0.5L to 5L over 0-20 years, not ideal but works for now
+            // 0.000137 = 1/(20*DAYSPERYEAR)
+            m_RBCproduction = int64_t( INFANT_RBC_PRODUCTION + ( _age * 0.000137) * ( ADULT_RBC_PRODUCTION - INFANT_RBC_PRODUCTION ) ); 
+            if(m_RBCproduction > ADULT_RBC_PRODUCTION)
+            {
+                m_RBCproduction = ADULT_RBC_PRODUCTION; // cap at adult production, overrun happens to infected people at age 7299.375-7300 days
+            }
+            m_inv_microliters_blood = float( 1 / ( ( 0.225 * ( _age / DAYSPERYEAR ) + 0.5 ) * 1e6 ) );
         }
+        m_RBCcapacity = m_RBCproduction * AVERAGE_RBC_LIFESPAN; // Health equilibrium of RBC is production*lifetime
     }
 
     void SusceptibilityMalaria::countAntibodyVariations()

Regression/Malaria/101_Malaria_ReportInterventionData/output/InsetChart.json

@@ -8735,7 +8735,7 @@
                 0.007477736100554,
                 0.008269515819848,
                 0.008843364194036,
-                0.007301237434149,
+                0.007301236968488,
                 0.007040482480079,
                 0.006629044190049,
                 0.00649824924767,
@@ -22053,8 +22053,8 @@
     },
     "Header": {
         "Channels": 30,
-        "DTK_Version": "2.29.6 antibody_decay_improvements(7f57409a) Nov  4 2025 11:39:54",
-        "DateTime": "Tue Nov  4 13:39:33 2025",
+        "DTK_Version": "2.30.0 gh152_BloodCapacity_Calculation_Fix(050fe88582) Jan  7 2026 09:48:56",
+        "DateTime": "Wed Jan  7 11:06:41 2026",
         "Report_Type": "InsetChart",
         "Report_Version": "3.2",
         "Simulation_Timestep": 1,

Regression/Malaria/101_Malaria_ReportInterventionData/output/InsetChart.linux.json

@@ -5902,9 +5902,9 @@
                 0.0003566804807633,
                 0.000390064669773,
                 0.0004215698863845,
-                0.0004461080825422,
-                0.0004527047276497,
-                0.0004664439184126,
+                0.0004461080534384,
+                0.0004527046985459,
+                0.0004664438893087,
                 0.000462149415398,
                 0.0004665091109928,
                 0.0004663094587158,
@@ -5920,8 +5920,8 @@
                 0.0004726638144348,
                 0.0004671269853134,
                 0.0004466707468964,
-                0.0004189886385575,
-                0.0003876005939674,
+                0.0004189886676613,
+                0.0003876006230712,
                 0.0003202469379175,
                 0.0002837656065822,
                 0.0002754237793852,
@@ -15153,8 +15153,8 @@
     },
     "Header": {
         "Channels": 30,
-        "DTK_Version": "2.29.6 antibody_decay_improvements(7f57409a) Nov  4 2025 11:39:54",
-        "DateTime": "Tue Nov  4 13:39:25 2025",
+        "DTK_Version": "2.30.0 gh152_BloodCapacity_Calculation_Fix(050fe88582) Jan  7 2026 09:48:56",
+        "DateTime": "Wed Jan  7 11:06:33 2026",
         "Report_Type": "InsetChart",
         "Report_Version": "3.2",
         "Simulation_Timestep": 1,