Timeline of Immune Response After Pathogen Entry
| Time After Exposure | Event | Type of Immunity |
|---|---|---|
| 0 seconds | Skin/mucous membrane barrier engaged | Innate — Physical |
| Minutes | Complement activated; stomach acid neutralizes ingested pathogens | Innate — Physiological |
| 1-4 hours | Neutrophils arrive at infection site; phagocytosis begins | Innate — Cellular |
| 4-24 hours | Macrophages arrive; NK cells activated; interferons secreted | Innate — Cellular + Cytokine |
| 24-96 hours | Macrophages present antigen to CD4+ T-helper cells (APC function) | Bridge: Innate → Adaptive |
| Day 4-7 | T-helper cells activated; B-cells begin activation; clonal expansion starts | Adaptive — Primary Response Begins |
| Day 7-14 | Peak primary antibody response (IgM dominant, then IgG class switch) | Adaptive — Humoral Peak |
| Day 14-21 | Cytotoxic T-cells eliminate infected cells; pathogen cleared | Adaptive — CMI Peak |
| Day 21+ | Effector cells die; memory B and T-cells persist long-term | Memory Formation |
| Second exposure (months-years later) | Memory cells activated within 1-3 days; large IgG response | Secondary (Memory) Response — ADAPTIVE |
Timeline: Plasmodium Life Cycle in Humans
| Time | Stage | Location |
|---|---|---|
| Day 0 | Sporozoites injected by mosquito | Bloodstream |
| Day 1-14 | Liver schizogony (pre-erythrocytic) | Liver hepatocytes |
| Day 14+ | Merozoites infect RBCs; erythrocytic cycle begins | Red blood cells |
| Every 48h | RBC lysis; haemozoin + merozoites released; fever spike | Blood |
| Week 3-4 | Some merozoites → gametocytes | Red blood cells |
| Mosquito bite | Gametocytes taken up; sexual cycle begins in mosquito | Mosquito midgut |