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Vertical Transmission of Babesia microti, US

Posted: Mon 2 Jul 2012 16:15
by X-member
"Volume 18, Number 8—August 2012

Vertical Transmission of Babesia microti, United States

Julie T. Joseph , Kerry Purtill, Susan J. Wong, Jose Munoz, Allen Teal, Susan Madison-Antenucci, Harold W. Horowitz1, Maria E. Aguero-Rosenfeld1, Julie M. Moore, Carlos Abramowsky, and Gary P. Wormser" ... rticle.htm

A quote (more to read on the link):
Babesiosis is usually acquired from a tick bite or through a blood transfusion. We report a case of babesiosis in an infant for whom vertical transmission was suggested by evidence of Babesia spp. antibodies in the heel-stick blood sample and confirmed by detection of Babesia spp. DNA in placenta tissue.

Re: Vertical Transmission of Babesia microti, US

Posted: Mon 2 Jul 2012 19:50
by RitaA
Thanks for posting this, Carina.

After a quick survey of the internet, I learned that vertical transmission of Babesiosis is something that has been considered and studied for a number of years -- and especially by veterinarians. This is probably the most concise summary of Babesiosis I came across (even though some of the information may now be slightly out of date):
Pediatric Babesiosis

Updated: Jul 29, 2010

Human babesiosis is an emerging tick-borne zoonotic disease caused by the protozoan parasites of the genus Babesia.[1] Babesial parasites and those of the closely related genus Theileria have worldwide distribution, parasitizing the erythrocytes of wild and domestic animals. These parasites are commonly called piroplasms because of the pear-shaped forms found within infected RBCs. Babesial infections in humans are infrequent and occur in limited geographic locations. Disease manifestations range from asymptomatic infection in healthy individuals to severe illness and death in those who are asplenic, elderly, or immunocompromised.

Babes first described babesiosis in Romanian cattle in 1888. Skrabalo was the first to identify a human infection caused by Babesia in 1957 in the former Yugoslavia. Earlier reports involved splenectomized patients with fulminant babesiosis. In 1969, infection with Babesia microti was described in a patient with an intact spleen from Nantucket Island off the coast of Massachusetts. Babesiosis is endemic in the Northeast, particularly in the areas of Nantucket Island, Martha's Vineyard, Shelter Island, and parts of Long Island. Cases have been reported from the Midwest and West Coast of the United States.

Of the more than 70 species worldwide in the genus Babesia, human infections are largely due to the rodent strain B microti (found only in the United States) and the cattle strains Babesia divergens and Babesia bovis (found only in Europe). Sporadic cases of babesiosis due to Babesia duncani (isolates WA-1 and CA-5) have been reported in Washington and northern California. Genetic sequence analysis of WA-1 strain has revealed piroplasm-specific, small-subunit ribosomal DNA. Phylogenetically, WA-1 strain Babesia is closely related to Babesia gibsoni, a canine pathogen. A fatal case of babesiosis was recently described in Missouri from a strain (MO-1) that was closely related to B divergens. Serologic studies that test for B microti do not detect infections due to these other strains of Babesia.

Babesia species in the host erythrocyte vary in size from 1-5 mm in length. B microti measures 2 X 1.5 mm, B divergens measures 4 X 1.5 mm, and B bovis measures 2.4 X 1.5 mm. They are pear-shaped, oval, or round. Their ring form and peripheral location in the erythrocyte frequently lead to their being mistaken for Plasmodium falciparum.

Babesiosis is a zoonotic disease and requires transmission from an animal reservoir to humans via a tick vector.[2] In the northeastern United States, the black-legged deer tick Ixodes scapularis, also called Ixodes dammini (see the image below), is the principal vector for transmitting the etiologic agent B microti. I scapularis is the same vector that transmits Lyme disease.

Babesia species from rodents, primarily the white-footed deer mouse but also the field mouse, vole, rat, and chipmunk, are transmitted to humans during tick bites in endemic areas. Babesiosis is understandably more prevalent during the periods of tick activity such as spring and summer.

The tick I scapularis has 3 developmental stages, the larva, the nymph, and the adult, with each stage requiring a blood meal for development into the next stage. As a larva and nymph, the tick feeds on rodents; however, as an adult, the tick prefers to feed on the white-tailed deer. Female ticks are impregnated while obtaining their blood meal on the deer, with the formation of up to 20,000 eggs.

Although rodents are infected with Babesia (60% on Nantucket Island), the white-tailed deer does not carry the organism. B microti is transmitted from the larval phase of the tick to the nymphal phase (transstadial transmission) but not transovarially. Human infection is primarily produced by the bite of an infected nymph during a blood meal. Restocking of deer populations and curtailment of hunting has increased deer herds in certain areas. The proximity of deer, mouse, and tick create the conditions for human infection. Babesiosis is rarely acquired through blood transfusion.[3] In transfusion-associated cases, sources of babesiosis have included platelets and frozen erythrocytes. The incubation period in transfusion-associated disease appears to be 6-9 weeks. Transplacental transmission has also occurred rarely.

The hard-bodied cattle tick Ixodes ricinus is thought to transmit bovine babesiosis from the cattle reservoir to humans in Europe.
Babesiosis has been getting a lot of attention lately, and especially when it concerns possible transmission by blood transfusion.

Here are a few abstracts that demonstrate how important it is for people in various professions to work together when it comes to Babesiosis and other tick-borne diseases:
N Engl J Med. 1998 Jul 16;339(3):160-5.

Persistent parasitemia after acute babesiosis.

Krause PJ, Spielman A, Telford SR 3rd, Sikand VK, McKay K, Christianson D, Pollack RJ, Brassard P, Magera J, Ryan R, Persing DH.


Department of Pediatrics, Connecticut Children's Medical Center and University of Connecticut School of Medicine, Hartford 06106, USA.


Babesiosis, a zoonosis caused by the protozoan Babesia microti, is usually not treated when the symptoms are mild, because the parasitemia appears to be transient. However, the microscopical methods used to diagnose this infection are insensitive, and few infected people have been followed longitudinally. We compared the duration of parasitemia in people who had received specific antibabesial therapy with that in silently infected people who had not been treated.

Forty-six babesia-infected subjects were identified from 1991 through 1996 in a prospective, community-based study designed to detect episodes of illness and of seroconversion among the residents of southeastern Connecticut and Block Island, Rhode Island. Subjects with acute babesial illness were monitored every 3 months for up to 27 months by means of thin blood smears, Bab. microti polymerase-chain-reaction assays, serologic tests, and questionnaires.

Babesial DNA persisted in the blood for a mean of 82 days in 24 infected subjects without specific symptoms who received no specific therapy. Babesial DNA persisted for 16 days in 22 acutely ill subjects who received clindamycin and quinine therapy (P=0.03), of whom 9 had side effects from the treatment. Among the subjects who did not receive specific therapy, symptoms of babesiosis persisted for a mean of 114 days in five subjects with babesial DNA present for 3 or more months and for only 15 days in seven others in whom the DNA was detectable for less than 3 months (P<0.05); one subject had recrudescent disease after two years.

When left untreated, silent babesial infection may persist for months or even years. Although treatment with clindamycin and quinine reduces the duration of parasitemia, infection may still persist and recrudesce and side effects are common. Improved treatments are needed.

[PubMed - indexed for MEDLINE]
Free full text
Emerg Infect Dis. 2004 Apr;10(4):622-9.

Babesia divergens-like infection, Washington State.

Herwaldt BL, de Bruyn G, Pieniazek NJ, Homer M, Lofy KH, Slemenda SB, Fritsche TR, Persing DH, Limaye AP.

Centers for Disease Control and Prevention, Atlanta, Georgia, USA.

Most reported U.S. zoonotic cases of babesiosis have occurred in the Northeast and been caused by Babesia microti. In Washington State, three cases of babesiosis have been reported previously, which were caused by WA1 (for "Washington 1")-type parasites. We investigated a case of babesiosis in Washington in an 82-year-old man whose spleen had been removed and whose parasitemia level was 41.4%. The complete 18S ribosomal RNA gene of the parasite was amplified from specimens of his whole blood by polymerase chain reaction. Phylogenetic analysis showed the parasite is most closely related, but not identical, to B. divergens (similarity score, 99.5%), a bovine parasite in Europe. By indirect fluorescent-antibody testing, his serum reacted to B. divergens but not to B. microti or WA1 antigens. This case demonstrates that babesiosis can be caused by novel parasites detectable by manual examination of blood smears but not by serologic or molecular testing for B. microti or WA1-type parasites.

[PubMed - indexed for MEDLINE]
Free PMC Article
Interdiscip Perspect Infect Dis. 2009;2009:984568. Epub 2009 Aug 27.

Update on babesiosis.

Vannier E, Krause PJ.

Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, 800 Washington Street, Box 041, Boston, MA 02111, USA.


Human babesiosis is an emerging tick-borne infectious disease caused by intraerythrocytic protozoan species of the genus Babesia with many clinical features similar to those of malaria. Over the last 50 years, the epidemiology of human babesiosis has changed from a few isolated cases to the establishment of endemic areas in the northeastern and midwestern United States. Episodic cases are reported in Europe, Asia, Africa, and South America. The severity of infection ranges from asymptomatic infection to fulminant disease resulting in death, although the majority of healthy adults experience a mild-to-moderate illness. People over the age of 50 years and immunocompromised individuals are at the highest risk of severe disease, including those with malignancy, HIV, lacking a spleen, or receiving immunosuppressive drugs. Asymptomatic carriers present a blood safety risk when they donate blood. Definitive diagnosis of babesial infection generally is made by microscopic identification of the organism on thin blood smear, amplification of Babesia DNA using PCR, and detection of Babesia antibody in acute and convalescent sera. Specific antimicrobial therapy consists of atovaquone and azithromycin or clindamycin and quinine. Exchange transfusion is used in severe cases. The use of multiple prevention strategies is recommended and consists of personal, residential, and community approaches.

[PubMed - in process]
Free PMC Article
Clin Microbiol Rev. 2011 Jan;24(1):14-28.

Transfusion-transmitted Babesia spp.: bull's-eye on Babesia microti.

Leiby DA.

Transmissible Diseases Department, American Red Cross Holland Laboratory, 15601 Crabbs Branch Way, Rockville, MD 20855, USA.

Babesia spp. are intraerythrocytic protozoan parasites of animals and humans that cause babesiosis, a zoonotic disease transmitted primarily by tick vectors. Although a variety of species or types of Babesia have been described in the literature as causing infection in humans, the rodent parasite Babesia microti has emerged as the focal point of human disease, especially in the United States. Not only has B. microti become established as a public health concern, this agent is increasingly being transmitted by blood transfusion: estimates suggest that between 70 and 100 cases of transfusion-transmitted Babesia (TTB) have occurred over the last 30 years. A recent upsurge in TTB cases attributable to B. microti, coupled with at least 12 fatalities in transfusion recipients diagnosed with babesiosis, has elevated TTB to a key policy issue in transfusion medicine. Despite clarity on a need to mitigate transmission risk, few options are currently available to prevent the transmission of B. microti by blood transfusion. Future mitigation efforts may stress serological screening of blood donors in regionalized areas of endemicity, with adjunct nucleic acid testing during the summer months, when acute infections are prevalent. However, several hurdles remain, including the absence of a licensed blood screening assay and a thorough cost-benefit analysis of proposed interventions. Despite current obstacles, continued discussion of TTB without proactive intervention is no longer a viable alternative.

[PubMed - indexed for MEDLINE]
Free PMC Article
Emerg Infect Dis. 2011 Jan;17(1):114-6.

Babesiosis in immunocompetent patients, Europe.

Martinot M, Zadeh MM, Hansmann Y, Grawey I, Christmann D, Aguillon S, Jouglin M, Chauvin A, De Briel D.

Service de Médecine Interne et Rhumatologie, Hôpitaux Civils De Colmar, Colmar, France.

We report 2 cases of babesiosis in immunocompetent patients in France. A severe influenza-like disease developed in both patients 2 weeks after they had been bitten by ticks. Diagnosis was obtained from blood smears, and Babesia divergens was identified by PCR in 1 case. Babesiosis in Europe occurs in healthy patients, not only in splenectomized patients.

[PubMed - indexed for MEDLINE]
Free PMC Article
Parasit Vectors. 2011 Feb 10;4:17.

Small risk of developing symptomatic tick-borne diseases following a tick bite in The Netherlands.

Tijsse-Klasen E, Jacobs JJ, Swart A, Fonville M, Reimerink JH, Brandenburg AH, van der Giessen JW, Hofhuis A, Sprong H.

Laboratory for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control Netherlands, National Institute for Public Health and Environment (RIVM), Bilthoven, The Netherlands.

In The Netherlands, the incidence of Lyme borreliosis is on the rise. Besides its causative agent, Borrelia burgdorferi s.l., other potential pathogens like Rickettsia, Babesia and Ehrlichia species are present in Ixodes ricinus ticks. The risk of disease associated with these microorganisms after tick-bites remains, however, largely unclear. A prospective study was performed to investigate how many persons with tick-bites develop localized or systemic symptoms and whether these are associated with tick-borne microorganisms.

In total, 297 Ixodes ricinus ticks were collected from 246 study participants who consulted a general practitioner on the island of Ameland for tick bites. Ticks were subjected to PCR to detect DNA of Borrelia burgdorferi s.l., Rickettsia spp., Babesia spp. or Ehrlichia/Anaplasma spp.. Sixteen percent of the collected ticks were positive for Borrelia burgdorferi s.l., 19% for Rickettsia spp., 12% for Ehrlichia/Anaplasma spp. and 10% for Babesia spp.. At least six months after the tick bite, study participants were interviewed on symptoms by means of a standard questionnaire. 14 out of 193 participants (8.3%) reported reddening at the bite site and 6 participants (4.1%) reported systemic symptoms. No association between symptoms and tick-borne microorganisms was found. Attachment duration ≥24 h was positively associated with reddening at the bite site and systemic symptoms. Using logistic regression techniques, reddening was positively correlated with presence of Borrelia afzelii, and having 'any symptoms' was positively associated with attachment duration.

The risk of contracting acute Lyme borreliosis, rickettsiosis, babesiosis or ehrlichiosis from a single tick bite was <1% in this study population.

[PubMed - indexed for MEDLINE]
Free PMC Article
Parasit Vectors. 2011 Oct 3;4:192.

Towards an integrated approach in surveillance of vector-borne diseases in Europe.

Braks M, van der Giessen J, Kretzschmar M, van Pelt W, Scholte EJ, Reusken C, Zeller H, van Bortel W, Sprong H.

Laboratory for Zoonoses and Environmental Microbiology, National Institute for Public Health and Environment (RIVM), Antonie van Leeuwenhoeklaan 9, Bilthoven, the Netherlands.

Vector borne disease (VBD) emergence is a complex and dynamic process. Interactions between multiple disciplines and responsible health and environmental authorities are often needed for an effective early warning, surveillance and control of vectors and the diseases they transmit. To fully appreciate this complexity, integrated knowledge about the human and the vector population is desirable. In the current paper, important parameters and terms of both public health and medical entomology are defined in order to establish a common language that facilitates collaboration between the two disciplines. Special focus is put on the different VBD contexts with respect to the current presence or absence of the disease, the pathogen and the vector in a given location. Depending on the context, whether a VBD is endemic or not, surveillance activities are required to assess disease burden or threat, respectively. Following a decision for action, surveillance activities continue to assess trends.

[PubMed - indexed for MEDLINE]
Free PMC Article
It's very possible that Babesiosis will eventually be found in areas not currently considered endemic. Here is one example from North America: ... /GE-3083.1
Article Citation:

Kerry Clark, Kyla Savick, and Joseph Butler (2012) Babesia microti in rodents and raccoons from northeast Florida. Journal of Parasitology In-Press.

Regular Article

Babesia microti in rodents and raccoons from northeast Florida

Kerry Clark, Ph.D.1, Kyla Savick2, and Joseph Butler3
a University of North Florida, Associate Professor, Public Health, University of North Florida

b Department of BiologyUniversity of North Florida

c Department of BiologyUniversity of North Florida


ABSTRACT: Human babesiosis in the United States is caused most commonly by the intraerythrocytic protozoan parasite, Babesia microti. Although a few reports have described evidence of Babesia species in animals in Florida, to date Babesia microti specifically has not been reported from Florida or most other southern states. To determine if the organism is present in vertebrates in the region, small mammals were trapped and sampled at 2 sites in northeastern Florida, and DNA extracts from blood samples were screened for B. microti DNA via PCR assays targeting portions of the nuclear small subunit rRNA (18S rDNA) and beta-tubulin genes. Amplified fragments from representative samples of PCR positive hosts were sequenced and compared phylogenetically to reference strains of Babesia species. The B. microti strains found in cotton rats most closely resembles B. microti sensu stricto strains that are pathogenic to humans, and strains found in raccoons most closely resemble previously described raccoon-related strains of B. microti sensu lato. The results of this study suggest that B. microti is prevalent among cotton rats and raccoons at some sites in northeast Florida, and may pose a risk to humans in the region.

Received: January 6, 2012; Revised: May 18, 2012; Accepted: May 30, 2012

Re: Vertical Transmission of Babesia microti, US

Posted: Fri 6 Jul 2012 15:45
by Joanne60
[url][/url] Further news article on vertical transmission with quotes from Wormser. It goes on to say' Lyme disease, the most common tick-borne illness, also can be transmitted from mother to unborn baby, but that, too, is rare, experts said.' I wonder which experts said that.
What a pity though that this wasn't properly investigated in 2002 how many other cases could have been helped.

Re: Vertical Transmission of Babesia microti, US

Posted: Fri 6 Jul 2012 18:29
by inmacdonald
Vertical Transmission of babesiosis - Strains other than B. Microti

Current reviews of human babesiosis have called attention to strains of Babesia
which differ from the microti strain.
Babesia duncani ( formerly WA1) first identified in Washington State and later in California
has by reports from practitioners in the States of Pennsylvania and Virginia, relocated to
states where it was previously unknown.
Serology confirmation of babesiosis is dependent on STRAIN specific immunodiagnostic reagents.
The Laboratory testing materials for confirmation of Babesia micoti do not work on babesia
Animal strains of babesia are likewise diverse, and tend to show species specificity.
Babesia divergens infections in humans have been documented in humans, and pose a more
significant threat/mortality outcome when compared with babesia microti infections.
All immunocompromised and asplenic patients are at high risk for morbidity/mortality.
The human fetus in utero is an immunocompromised host.
It is not known what the percentage of fetal loss is in human transplacental babesiosis,
because full autopsies and babesia focused autopsies are not conducted on miscarried fetuses.
Asymptomatic mothers with subclinical babesiosis arefully capable of transmitting the infection
to their fetuses.

In veterinary models, babesiosis was and is a cause of fetal death and death in adult animals.
These studies date to the work of Dr Theobald Smith and colleagues in 1893 in Texas.

Lyme disease and babesiosis may be simultaneously transmitted by a single tick bite.
Transplacetal Lyme disease has a variety of fetal outcomes ( with or without concurrent babesiosis)
Patients who receive prompt penicillin therapy do well. Patients with undiagnosed Gestational
Lyme Disease may experience adverse pregnancy outcomes. An inflammatory reaction to
spirochetal infection by the fetus in utero is often absent, due to the immune modulations of
human pregnancy and due to the immaturity of the fetal immune system while in utero.

The Placenta is not a barrier to the interchange of maternal blood with fetal blood.
It is documented that for male fetuses, the Y chromosome is detectable in maternal blood
for several hours after delivery in a normal uncomplicated full term pregnancy.
Feto-maternal hemorrhage is routine enough that RhoGAm is administered to Rh negative mothers
who bear Rh positive infants to avoid the development of Hemolytic disease of the newborn
in subsequent pregnancies. The Dosage ( Units/number of vials of RhoGAm) is titrated by the
results of the Kleihauer Betke Test of maternal postpartum blood.

Clinical signs of Babesiosis in a newborn may include:

Re: Vertical Transmission of Babesia microti, US

Posted: Sat 7 Jul 2012 3:12
by RitaA
Joanne60 wrote:[url][/url] Further news article on vertical transmission with quotes from Wormser. It goes on to say' Lyme disease, the most common tick-borne illness, also can be transmitted from mother to unborn baby, but that, too, is rare, experts said.' I wonder which experts said that.
What a pity though that this wasn't properly investigated in 2002 how many other cases could have been helped.
Thanks, Joanne.

Here's the article from the link you posted above. I find the content sometimes becomes unavailable after a few months, so I did a quick cut-and-paste:
Tick secret revealed: Westchester researchers first to prove baby got babesiosis before birth

12:40 AM, Jul 6, 2012

Westchester County researchers have confirmed for the first time a case of a pregnant woman passing on babesiosis, an increasingly common tick-borne illness, to her unborn baby.

The finding is important because it gives physicians another cause to investigate when evaluating infants with symptoms that can’t be easily explained.

“Babesiosis shouldn’t be on the top of the list,” said Dr. Gary Wormser, a tick-borne-disease expert at New York Medical College and chief of infectious diseases at Westchester Medical Center. “But it should be on the list — especially in areas like ours where it is becoming increasingly common.”

The finding comes during what is turning out to be a normal tick season despite early indications the mild winter would lead to a bumper tick crop.

In a paper that will be published next month in Emerging Infectious Diseases, a prestigious journal from the Centers for Disease Control and Prevention, researchers from New York Medical College and Westchester Medical Center describe the case of a 6-week-old Yorktown Heights girl admitted to the hospital with unusual symptoms.

It took a sharp-eyed technician to note babesia parasites, which cause babesiosis, in the baby’s blood sample.

The baby recovered after five days in the hospital during which she was given antibiotics. Physicians chalked up her illness to babesiosis infection contracted before birth. But they never really knew for sure.

Years later, when researchers in Westchester were looking into a rise in the number of babesiosis cases in the Lower Hudson Valley, they re-examined the case. By tracking down samples saved from the placenta as well as blood from the baby and mother, researchers showed that the infant was born with babesiosis, said Wormser.

“The results were definitive,” Wormser said.

There have been four previously cited incidences where doctors suspected a baby had been infected with babesiosis before birth. But the case of the Yorktown Heights child was the first time it was proved.

The disease first was seen in the Lower Hudson Valley in 2001 . The Yorktown Heights girl was born in summer of 2002.

(Page 2 of 2)

Pregnant women should be especially vigilant about checking themselves for ticks when they have been outdoors, said Dr. Julie T. Joseph, lead author of the paper.

“Babesiosis is an emerging infectious disease in the Hudson Valley,” she said. “Pregnant women should be aware of the risk and should check for ticks.”

Passing the disease on to an unborn baby is possible, but likely doesn’t happen often, she said.

“People shouldn’t panic,” she said.

Two other deer-tick-borne diseases are identified in humans in the region: Lyme disease and human granulocytic anaplasmosis, also known as ehrlichiosis. Lyme disease, the most common tick-borne illness, also can be transmitted from mother to unborn baby, but that, too, is rare, experts said.

Tick experts in the Lower Hudson Valley report seeing the usual number of ticks and tick-related diseases this year.

“Nothing out of the ordinary,” said Amy Albam, senior horticulturist and diagnostic lab educator at Cornell University Cooperative Extension of Rockland County in Stony Point.

Some had theorized the warm winter might encourage an overabundance of ticks. But health experts said that does not appear to be the case.

“I expected the numbers would have risen,” said Tom Daniels, co-director of the Vector Ecology Laboratory at Louis Calder Center in Armonk. “But we’re not seeing it. It’s a bit of a mystery.”

Most people who contract babesiosis don’t even know it. The mother of the baby born with the disease told investigators that she did not recall getting a tick bite and never had any symptoms of a tick-related disease.

It is too early in the season to tally the number of Lyme disease cases, experts said. Checking for ticks remains the best way to prevent getting a tick-borne disease.

Re: Vertical Transmission of Babesia microti, US

Posted: Thu 17 Sep 2015 5:06
by RitaA
Getting back to the original post and some research carried out in mice:
X-member wrote:"Volume 18, Number 8—August 2012

Vertical Transmission of Babesia microti, United States

Julie T. Joseph , Kerry Purtill, Susan J. Wong, Jose Munoz, Allen Teal, Susan Madison-Antenucci, Harold W. Horowitz1, Maria E. Aguero-Rosenfeld1, Julie M. Moore, Carlos Abramowsky, and Gary P. Wormser" ... rticle.htm

A quote (more to read on the link):
Babesiosis is usually acquired from a tick bite or through a blood transfusion. We report a case of babesiosis in an infant for whom vertical transmission was suggested by evidence of Babesia spp. antibodies in the heel-stick blood sample and confirmed by detection of Babesia spp. DNA in placenta tissue.
This latest research does seem to confirm that vertical transmission of Babesia microti is very possible in mammals -- including mice and human beings.
PLoS One. 2015 Sep 15;10(9):e0137731. doi: 10.1371/journal.pone.0137731. eCollection 2015.

Vertical Transmission of Babesia microti in BALB/c Mice: Preliminary Report.

Bednarska M1, Bajer A1, Drozdowska A1, Mierzejewska EJ1, Tolkacz K1, Welc-Falęciak R1.

Author information

1Department of Parasitology, Institute of Zoology, Faculty of Biology, University of Warsaw, 1 Miecznikowa Street, Warsaw, Poland.


Babesia spp. (Apicomplexa, Piroplasmida) are obligate parasites of many species of mammals, causing a malaria-like infection- babesiosis. Three routes of Babesia infection have been recognized to date. The main route is by a tick bite, the second is via blood transfusion. The third, vertical route of infection is poorly recognized and understood. Our study focused on vertical transmission of B. microti in a well-established mouse model. We assessed the success of this route of infection in BALB/c mice with acute and chronic infections of B. microti. In experimental groups, females were mated on the 1st day of Babesia infection (Group G0); on the 28th day post infection (dpi) in the post- acute phase of the parasite infection (G28); and on the 90th and 150th dpi (G90 and G150 group, respectively), in the chronic phase of the parasite infection. Pups were obtained from 58% of females mated in the post-acute phase (G28) and from 33% of females in groups G90 and G150. Mice mated in the pre-acute phase of infection (G0) did not deliver pups. Congenital B. microti infections were detected by PCR amplification of Babesia 18S rDNA in almost all pups (96%) from the experimental groups G28, G90 and G150. Parasitaemia in the F1 generation was low and varied between 0.01-0.001%. Vertical transmission of B. microti was demonstrated for the first time in BALB/c mice.

[PubMed - in process]