There may be a century between the last two pandemics, but this does not mean that we will be sunny for the next 100 years. If another pandemic happens soon, scientists at the University of Colorado at Boulder are exploring the secrets of plankton to be proactive rather than reactive.

In a paper published in the journal American Naturalist, the research team stated that the initial immune response of an infected organism is an important part of determining how the pathogen spreads.

"One of the biggest patterns we see in disease ecology and epidemiology is that not all hosts are equal," said Tara Stewart Merrill, the first author of the paper and a postdoctoral researcher in ecology. Merrill) said.

From parasitic flatworms and mosquitoes to pigs and bats, dangerous pathogens can easily be passed from the animal kingdom to humans. It is the same process every time-animals are infected with pathogens and then spread to humans through catalogs or through third-party hosts.

But why must this be the case? Stewart Merrill said, what if the host is likely to overcome the disease and break the chain that transmits it to humans?

"In infectious disease research, we hope to incorporate host immunity into our understanding of how the disease spreads," explains Stuart Merrill.

Ecologists work with zooplankton, a small daphnia, to better understand and describe the response of invertebrates to pathogen infection. First, the researchers exposed zooplankton to the fungal parasite Metschnikowia bicuspidate. Parasites are killed by attacking the animal’s intestines, filling its body, and growing until the host is finally released when it dies.

According to this study, some plankton are good at preventing fungal spores from entering their bodies, while others clear the infection within a limited window after ingesting the spores. However, the most interesting reaction recorded by Stewart Merrill indicates that some plankton that was doomed to fail can recover.

In subsequent experiments, Stewart Merrill proved that the success or failure of pathogen infection depends on the internal defense strength of plankton within a limited window including the onset of exposure.

"Our results show that invertebrates can use multiple defense mechanisms to reduce the likelihood of infection, and we really need to understand these immune defense mechanisms to understand infection patterns," said Stewart Merrill.

Based on the research results, Stewart Merrill and her team developed a simple probabilistic model to measure host immunity, which can be applied to wildlife systems.

Although the direct application of this model is very suitable for invertebrates, such as malaria-transmitting mosquitoes, which account for nearly 20% of global infectious diseases; the researchers said the model can be easily adjusted. For example, similar models can be used to help predict the occurrence and spread of zoonotic spillover events in the future, such as those that triggered the COVID-19 pandemic.

Stewart Merrill said she hopes that a better understanding of infections in simple animals like plankton can be applied to animals that are vital to human health.

She concluded: "We really need to work on understanding the prevention of infection, not just curing the infection."

Photo: A zooplankton infected by the fungal parasite Metschnikowia bicuspidate. The tiny fungal spores that fill the body are visible like black fuzzy spots. Credit: Tara Stewart Merrill Lynch

Laboratory equipment is supported by Labcompare, a purchasing guide for laboratory professionals.