Related Experiment Video

Updated: May 24, 2026

A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness
12:21

A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness

Published on: September 28, 2022

Integrating infection intensity and aggregation into the dynamics of pathogens with within-host replication

Ruijiao Sun1, Jason Cosens Walsman1, Mark Wilber2

  • 1Marine Science Institute, University of California Santa Barbara, Santa Barbara, California, USA.

The Journal of Animal Ecology
|May 23, 2026
PubMed

Insights

Disease aggregation, common in macroparasites, also impacts microparasites like the amphibian chytrid fungus (Bd). Understanding infection intensity and aggregation is key to predicting disease dynamics and outcomes.

Area of Science:

  • Ecology
  • Epidemiology
  • Mathematical Biology

Background:

  • Disease outcomes are influenced by infection intensity, which varies greatly among hosts.
  • This variation, known as aggregation, is well-studied in macroparasites but less so in microparasites.
  • Incorporating aggregation into microparasite models is crucial for understanding disease dynamics.

Purpose of the Study:

  • To investigate mechanisms of aggregation in microparasite systems.
  • To determine how aggregation and load-dependent effects influence host suppression and virulence-transmission trade-offs.
  • To apply these concepts to the amphibian chytrid fungus (Batrachochytrium dendrobatidis - Bd).

Main Methods:

  • Developed differential equation models to dynamically simulate pathogen load distribution.
  • Incorporated both within- and between-host processes.
  • Applied the framework to the Bd-amphibian system.

Main Results:

  • Stronger load-dependent mortality and faster within-host replication reduce aggregation.
  • Aggregation weakens host suppression and flattens the virulence-transmission trade-off.
  • Peak transmission shifts to higher replication rates when aggregation is present.

Conclusions:

  • Mechanisms of infection intensity and aggregation similarly affect microparasite and macroparasite dynamics.
  • Provides a framework for integrating within-host processes into population-level disease models.
  • Advocates for a unified approach to disease modeling across parasite types.
Keywords:
chytrid fungushost–pathogen interactionsinfection intensityload‐dependent mortalitymicroparasitepathogen aggregationpathogen loadvirulence–transmission trade‐off

More Related Videos

Single-cell Quantitation of mRNA and Surface Protein Expression in Simian Immunodeficiency Virus-infected CD4+ T Cells Isolated from Rhesus macaques13:13

Single-cell Quantitation of mRNA and Surface Protein Expression in Simian Immunodeficiency Virus-infected CD4+ T Cells Isolated from Rhesus macaques

Published on: September 25, 2018

Measurement of In Vitro Integration Activity of HIV-1 Preintegration Complexes10:34

Measurement of In Vitro Integration Activity of HIV-1 Preintegration Complexes

Published on: February 22, 2017

Related Concept Videos

Infection01:20

Infection

When a pathogen enters the body and reproduces, it can cause an infection, damage body cells, and cause illness symptoms that eventually lead to disease. Therefore, its prevention requires breaking the chain of infection.
The chain begins with pathogens: bacteria, viruses, fungi, prions, or parasites such as protozoa helminths. These can be present on the skin as transient or resident flora, or they can be acquired from the environment. Identifying and treating the type of infection and...
Colonisation of Pathogens01:25

Colonisation of Pathogens

Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
Viral Replication: Lysogenic Cycle01:16

Viral Replication: Lysogenic Cycle

The lysogenic cycle is a crucial viral replication strategy that allows bacteriophages to persist within host cells without immediately destroying them. This process is primarily observed in temperate phages, such as bacteriophage lambda (λ), which infects Escherichia coli. The cycle allows the viral genome to persist across bacterial generations while keeping host cells viable.Integration of the Viral GenomeUpon infection, bacteriophage lambda attaches to the bacterial surface and injects its...
Viral Recombination00:57

Viral Recombination

Cells are sometimes infected by more than one virus at once. When two viruses disassemble to expose their genomes for replication in the same cell, similar regions of their genomes can pair together and exchange sequences in a process called recombination. Alternatively, viruses with segmented genomes can swap segments in a process called reassortment.
Stages of Infection01:26

Stages of Infection

Stages of infection describe what happens to a susceptible host once a pathogen invades the human body. The stages of infection are incubation, prodromal, illness, stage of decline, and convalescence. The incubation stage is the period from exposure to a pathogen until symptoms start. The infected person is unaware of impending illness as the pathogens grow and multiply within the body. The duration may vary depending on the type of infection. The incubation period of measles averages ten to...
Intracellular Movement of Viruses and Bacteria01:10

Intracellular Movement of Viruses and Bacteria

Intracellular bacteria and viruses often comprise a group of highly infectious pathogens that can cause several diseases. Bacterial pathogens include those belonging to the genus Rickettsia responsible for conditions such as rocky mountain spotted fever and the Mediterranean spotted fever; Chlamydia, a genus responsible for a sexually transmitted disease; Coxiella burnetii, an agent responsible for Q fever. Viral pathogens include vaccinia—a poxvirus, and herpes simplex virus—a virus that...