Babesiosis: It's a Dangerous, Malaria-like, Tick-Borne Disease and it's Increasing!
Updated: Oct 26, 2022
The sweats, chills, chest pain, fevers, cough, and air hunger that occur in many Lyme disease patients are actually classic symptoms for babesiosis, a parasitic infection that can be carried by the same tick that carries Lyme disease.
Babesia are microscopic parasites which are types of protozoans and there are more than one hundred species of them. Most Babesia infections that are transmitted to humans are due to at about a dozen species: Babesia microti and Babesia duncani (Babesia WA-1) are the most common ones in the United States, Babesia divergens which more commonly causes disease in Europe, as well as occasional human cases from types of Babesia that are more common in animals such as B. bovis ( the parasite that causes Texas cattle fever) B. equi, and B. caucasia.2, 3. Some of the species types found to infect people have not yet been given their own name and others, like Babesia microti, are not just one species but a group of similar unidentical subtypes. 2
What is Babesiosis?
"Babesiosis" is the condition of being infected by the Babesia protozoa; it can have a wide range of presentation including hemolytic disease like malaria, where a host's red blood cells become infected and damaged by the protozoa. Babesiosis is known to range in severity from asymptomatic to life threatening and can be spread through tick bites, as well as blood transfusions.
Prevalence of Babesiosis
Human babesiosis has been nationally reportable to the U.S. Centers for Disease
Control and Prevention since 2011. As of 2019, the number of reported cases more than doubled from 1,126 to 2,418. with 88% of cases involving residents of seven states in the Northeast and
upper Midwest, namely, Connecticut, Massachusetts, Minnesota, New Jersey, New York,
Rhode Island, and Wisconsin. 4 But it hasn't just stayed there.
Surveillance data from health departments in several states have demonstrated increasing incidence as well as spread over the past two decades. In New York State, the incidence of B. microti infection increased slightly less than 3-fold from 2006 to 2015, 5 and similar patterns have been observed in other states in which the pathogen is endemic.6 In Pennsylvania, a state not traditionally considered to be at high risk for B. microti transmission, the incidence of disease increased 10-fold between 2005 and 2015 and the geographic expansion of B. microti outside the traditional states in which the pathogen is endemic includes Delaware, Maine, Maryland, New Hampshire, and Virginia.1 Indeed, by 2019 Maine and Vermont reported case rates (10.3 and 5.4/100,000 population, respectively) similar to or higher than those reported by endemic states.4
The true number of cases for when babesiosis is diagnosed is likely far greater than the number of times it is reported! Take for example, the Lyme disease data from the CDC themselves. The CDC have posted on their website that the number of DIAGNOSED cases of Lyme disease is more than ten times over and beyond the number of cases REPORTED to them, with the difference going from approxiamtely 30,000 cases to over 476,000 cases in 2019.6
The matter is only worsened by the often asymptomatic infection present in healthy people, who then may donate blood and transmit the infection unknowingly. There currently is no Babesia test approved by the Food and Drug Administration (FDA) available for screening prospective blood donors. So if you are wondering: 'Can babesiosis be transmitted by transfusion in areas where it’s not spread by ticks?' The CDC themselves state "Yes. Because individuals who donate blood travel, and blood products are shipped around the country, babesiosis can be transmitted in areas that are not considered high risk for infection. In addition, bloodborne babesiosis may occur year-round, not only in warmer months when risk for tickborne infection peaks".7
Given this number of factors, it'd be almost more surprising if babesiosis wasn't spreading! But it is. What is surprising is how ill-informed so many clinicians remain about it. "B. microti infections in healthy individuals are usually silent and asymptomatic, with very low or undetectable levels of parasites, especially in younger age groups, as shown by sero-prevalence data from endemic regions, ranging from about 6% to 16 %, and the numbers of actual reported cases, and as such the disease prevalence is probably underestimated".8
The spread and increase of babesiosis is not unique to this country. In recent years, B. microti has increasingly been detected in rodents and ticks across Europe, Africa and Asia so much so that "[c]urrently, distribution of Babesia in its endemic regions is largely unknown".2 And that these organisms are spreading is no surprise given the similar increase in both black-legged deer ticks and bacteria responsible for Lyme disease. Remember, Babesia are using the same animal vectors and reservoirs as Lyme disease, principally ticks, deer and mice. With that, since Lyme disease is on the rise well beyond the 'REPORTED' range, so too, likely is Babesia. The spread of ticks and Lyme-disease was featured in a previous post and has been, in part, attributed to climate change. "The strongest climate-disease association observed was between warming temperatures and increasing incidence in the Northeast. ... We project that future climate change could substantially increase Lyme disease burden in the Northeast in coming decades under an upper climate change scenario".9
Symptoms of Babesiosis
For starters, the medical profession, as given a voice here using quotes from the Merck Manual Professional Version, readily acknowledges that "[a]symptomatic Babesia infection may persist for months to years and remain subclinical throughout its course in otherwise healthy people, especially those less than 40 years".10 So the inferred message to a clinician-in-training is that 'you will probably not see this much in practice unless dealing with very sick people'. And this is followed with: "When symptomatic, babesiosis usually starts after a 1- to 2-week incubation period with nonspecific symptoms including malaise, fatigue, chills, fever, headache, myalgia, and arthralgia. In healthy people, symptoms usually resolve after a week'".10 So the next inferred message to a clinician-in-training is that 'this infection is not really dangerous unless dealing with very sick people'. Thus most doctors don't look for this infection and it is marginalized to only affecting the immuno-compromised, in whom patients may have hemolytic anemia (due to red blood cells breaking down), jaundice, hepatosplenomegaly (enlargement of liver and spleen), thrombocytopenia (low platelet count), congestive heart failure, renal failure and perhaps even death.
Yet it is these general and non-specific symptoms of fatigue, malaise, and weakness, with an associated fever, shaking, chills, and excessive sweating that are incredibly common and can become the key to a good diagnosis. Some smaller subset of them often persist in patients with babesiosis, with or without Lyme disease, and can ultimately lead a careful clinician to ordering helpful tests to identify the infection. Many doctors, when confronted with these symptoms, might be mistaken and interpret them for the signs of a seasonal flu, as in a new patient this past week, who even experienced a tick bite and developed the symptoms after five days. He had sought help from an urgent care walk-in clinic and then later from an emergency room department, but neither treated him for tickborne illness, and only one of the two even tested him for Lyme disease. And this is written from within Connecticut during 2022!
Beyond just the symptoms this infection can cause on its own, consideration should be given for a more varied presentation for two reasons. One reason is that the complicated genetics of this constantly evolving parasite have shown to be frequently mutating into previously unrecognized forms associated with infections in humans.11,12 Secondly, "[t]his parasite exacerbates all of the typical Lyme symptoms, such as an increase in fatigue, joint pain, paresthesias, headaches, and cognitive dysfunction, often with the malaria-type symptoms listed above. Psychological problems, such as depression, anxiety, and mood swings, are also typically worsened with Babesia, which is why it should always be considered in patients presenting with multiple systemic symptoms and severe emotional issues that do not seem proportionate to their present situation or history of trauma".13
Many clinicians have been lulled into a sense of timidity, not pushing in a proactive way to get answers for their patients, diagnostically or by way of prescriptive treatment. They narrowly interpret laboratory findings without considering how good is the actual data they are looking at, and seem oblivious to the more complicated shifting organic face of medicine, preferring outdated and easier models taught from medical school.
For example, a case report from 2014 out of China found a boy to be infected with not just any type of Babesia, but Babesia venatorum, a species associated with occasional infections in Europe!15 How could this be? Well as several other types of Babesia have been shown to be spreading through rodent populations in Asia, which had previously been primarily associated with North America or Europe, couldn't this species be spreading as well?1,2,11,12
And if the question of geographic boundaries was not enough to get some clinicians thinking more critically, what about that diagnostic stereotype for Babesia largely affecting only immunocompromised people? The unfortunate Chinese youth featured in this study stood that generalization on its head too. "The patient in our study was presumed to be healthy and immunocompetent, which indicates that Babesia species can cause infections even in healthy persons".15
Check back later this summer for another blog on the diagnosis and treatment of babesiosis by Dr. Carney!
*image credits: Westblade LF, et al. Babesia microti: from Mice to Ticks to an Increasing Number of Highly Susceptible Humans. J Clin Microbiol. 2017 Oct;55(10):2903-2912. doi: 10.1128/JCM.00504-17. Epub 2017 Jul 26. PMID: 28747374; PMCID: PMC5625376.
Ron M. Walls MD, in Rosen's Emergency Medicine: Concepts and Clinical Practice, 2018.
https://www.cdc.gov/lyme/datasurveillance/index.html. Accessed 05-28-22.
Ord, Rosalynn Louise, and Cheryl A Lobo. “Human Babesiosis: Pathogens, Prevalence, Diagnosis and Treatment.” Current clinical microbiology reports vol. 2,4 (2015): 173-181. doi:10.1007/s40588-015-0025-z.
Couper LI, MacDonald AJ, Mordecai EA. Impact of prior and projected climate change on US Lyme disease incidence. Glob Chang Biol. 2021 Feb;27(4):738-754. doi: 10.1111/gcb.15435. Epub 2020 Nov 22. PMID: 33150704; PMCID: PMC7855786.
Kim JY, et al. First case of human babesiosis in Korea: detection and characterization of a novel type of Babesia sp. (KO1) similar to ovine babesia. J Clin Microbiol. 2007 Jun;45(6):2084-7. doi: 10.1128/JCM.01334-06. Epub 2007 Mar 28. PMID: 17392446; PMCID: PMC1933034.
Hong SH,et al. Detection and characterization of an emerging type of Babesia sp. similar to Babesia motasi for the first case of human babesiosis and ticks in Korea. Emerg Microbes Infect. 2019;8(1):869-878. doi: 10.1080/22221751.2019.1622997. PMID: 31179860; PMCID: PMC6566668.
Horowitz, R. Why Can't I Get Better? St. Martin's Press, New York. 2013. p.137.
** image credits: https://www.cdc.gov/dpdx/babesiosis/index.html
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