Black-legged tick nymph.
Professor Maria Duke Wasser’s Environmental Epidemiology Laboratory studies how human activity affects tick-borne diseases, including Lyme disease and babesiosis. Two new papers from current and former members of the lab–one has just been published and the other has been accepted for publication–provide new details about how these diseases incubate and spread. Here, Duke-Wasser discusses the papers’ findings and how they change our understanding of these diseases.
Prenatal transmission of infection from mother to child may lead to an increase in babesiosis (at least in mice).
The lab’s first paper looks at two pathogens: Borrelia burgdorferiwhich causes Lyme disease, and Babesia microti, which causes babesiosis, a disease that has been on the rise in the northeastern United States in recent years. Each of these pathogens is transmitted by the same black-legged tick and can infect the same host.
The pathogen that causes babesiosis can be passed from mother to child, which cannot happen with Lyme.
“One thing we’ve found is that transmission from mother to offspring is really key to Babesia’s ability to spread,” Duke Wasser said. “These findings are important because although our study is looking at mice, prenatal mother-to-child transmission of babesiosis has also been observed in humans.”
Mother-to-child transmission of Babesiosis appears to be responsible for its spread more than co-infection with Lyme disease.
Diuk-Wasser’s lab initially set out to explore how the pathogens that cause Lyme disease and babesiosis interact: do they help or suppress each other? Babesiosis is not as easily transmitted as Lyme, but it is on the rise, so their hypothesis was that the pathogen that causes Lyme promotes or facilitates the onset of Babesiosis.
“I was surprised to see how much more important mother-to-child transmission (among mice) was than co-infection with Lyme, which is what our initial hypothesis focused on,” said Duke Wasser.
The paper uses field data collected in Block Island, Rhode Island, along with laboratory data, to create a mathematical model that estimates the capacity of the pathogen causing Babesiosis to spread.
Climate change may be partly responsible for the emergence of babesiosis.
In the past, in the northeastern United States, many wild outdoor rats would die during the winter, while ticks lived on and transmitted pathogens. But Duke Wasser said, “We think more mice are overwintering now, and incubating Babesia During the winter, this is a minor factor driving the transmission.”
Different strains of Lyme disease thrive in different animal hosts, which may be why so many strains thrive.
There are always many strains of Lyme in the environment, some of which make people sicker than others. One question for the researchers is why Lyme doesn’t behave like other diseases, such as COVID-19, where one strain tends to take over, replicate and cause the vast majority of infections.
In their second paper, Diuk-Wasser’s lab set out to explore the idea that some Lyme strains may be better adapted to some animals than others. What they found is that certain strains of the pathogen that causes Lyme disease are more common in birds and others are more common in mice, which explains at least partly why you see them all in nature.
Birds are more important than known in the spread of Lyme disease.
“We initially thought the Lyme variants that cause the most severe disease in humans were the ones carried by mice, but this study shows that it’s actually more of a mix,” said Duke Wasser. Birds also incubate some strains that are dangerous to humans. This suggests that birds are more important than we thought in the spread of Lyme disease.”
The fact that there are multiple strains (more than 15) circulating simultaneously simultaneously allows us to get Lyme disease frequently, even in the same season. “It’s not like COVID-19, where one dominant strain spreads, and then a few months later another strain spreads,” Duke Wasser said. Because so many strains circulate, and because animals tend to carry multiple strains at once, herd immunity is never attainable, either in humans or animals.
This story originally appeared Columbia News.