Babesiosis
Encyclopedia
Babesiosis is a malaria-like
parasitic disease
caused by infection with Babesia
, a genus
of protozoa
l piroplasms
. After trypanosome
s, Babesia are thought to be the second most common blood parasites of mammals and they can have a major impact on health of domestic animals in areas without severe winters. Human babesiosis is uncommon, but reported cases have risen recently because of expanded medical awareness.
. Equine
babesiosis is also known as piroplasmosis (from the Latin piro, meaning pear
+ German
plasma, a thing formed).
tick
s. Babesia microti uses the same tick vector as Lyme disease
and Ehrlichiosis
, and may occur in conjunction with these other diseases. The organism can also be transmitted by blood transfusion
.
In North America, the disease is primarily found in eastern Long Island
, Fire Island, Nantucket Island and Martha's Vineyard
off of the coast of Massachusetts. More generally it can be found in the northern midwestern and New England states.
It is sometimes called "The Malaria of The Northeast." Cases of babesiosis have been reported in a wide range of European countries. Disease in Europe is usually due to infection with Babesia divergens
, while in the United States Babesia microti and Babesia duncani are the species most commonly associated with human disease. Babesiosis has also been observed in Korea
.
Babesiosis has emerged in Lower Hudson Valley, New York since 2001.
, with fevers up to 40.5°C (105°F), shaking chills, and severe anemia (hemolytic anemia). Organ failure may follow including adult respiratory distress syndrome. Severe cases occur mostly in people who have had their spleen removed surgically
. Severe cases are also more likely to occur in the very young, very old, and persons with immunodeficiency
, such as HIV/AIDS patients.
A reported increase in babesiosis diagnoses in the 2000s is thought to be caused by more widespread testing and higher numbers of people with immunodeficiencies coming in contact with ticks, the disease vector. Little is known about the occurrence of Babesia species in malaria-endemic
areas, where Babesia can easily be misdiagnosed as Plasmodium
.
Babesia parasites reproduce in red blood cell
s, where they can be seen as cross-shaped inclusions (4 merozoites asexually budding but attached together forming a structure looking like a "Maltese Cross
") and cause hemolytic anemia
, quite similar to malaria
.
Note that unlike the Plasmodium
parasites that cause malaria, Babesia species lack an exo-erythrocytic phase, so the liver is usually not affected.
In animals Babesia canis rossi, Babesia bigemina, and Babesia bovis
cause particularly severe forms of the disease that include a severe haemolytic anaemia, with positive erythrocyte-in-saline-agglutination test indicating an immune mediated component to the haemolysis. Common sequelae include haemoglobinuria "red-water", disseminated intravascular coaguation (DIC) and "cerebral babesiosis" caused by sludging of erythrocytes in cerebral capillaries.
In the Bovine species, the organism causes a hemolytic anemia. Due to this the animal will show pale mucus membranes initially. As the levels of billirubin (a byproduct of red blood cell lysis) continue to increase, there will be a yellowing of the visible mucus membranes (icterus) due to the failure of the liver to metabolise the excess bilirubin. Hemoglobinuria will be seen due to excretion of red blood cell lysis by-products via the kidneys. Fever of 40.5 °C (104.9 °F) develops due to release of inflammatory by-products.
within the preceding 9 weeks, so this aspect of the medical history is vital. Babesiosis may be suspected when a person with such an exposure history develops persistent fevers and hemolytic anemia. The definitive diagnostic test for babesiosis is the identification of parasites on a Giemsa-stained
thin blood smear
. So-called "Maltese cross formations" on the blood film are essentially diagnostic of babesiosis, since they are not seen in malaria, the primary differential diagnosis. Careful examination of multiple blood smears may be necessary, since Babesia may infect less than 1% of circulating red blood cells and thus be easily overlooked.
Serologic testing
for antibodies
against Babesia (both IgG and IgM
) can detect low-level infection in cases where there is a high clinical suspicion but negative blood film examinations. Serology is also useful for differentiating babesiosis from malaria
in cases where people are at risk for both infections. Since detectable antibody responses require approximately one week after infection to develop, serologic testing may be falsely negative early in the disease course.
A polymerase chain reaction
(PCR) test has been developed for the detection of Babesia from the peripheral blood. PCR may be at least as sensitive and specific
as blood film examination in diagnosing babesiosis, though it is also significantly more expensive. Most often, PCR testing is used in conjunction with blood film examination and possibly serologic testing
.
Other laboratory findings include decreased numbers of red blood cells and platelets on complete blood count
.
In animals Babesiosis is suspected by observation of clinical signs (haemoglobinuria and anaemia) in animals in endemic areas. Diagnosis is confirmed by observation of merozoites on thin film blood smear examined at maximum magnification under oil using Romonovski stains (methylene blue and eosin). This is a routine part of the veterinary examination of dogs and ruminants in regions where babesiosis is endemic.
Babesia canis and Babesia bigemina are "large babesias" that form paired merozoites in the erythrocytes , commonly described as resembling "two pears hanging together", rather than the "Maltese Cross" of the "small babesias". Their merozoites are approximately twice the size of small babesias.
Cerebral babesiosis is suspected in-vivo when neurological signs (often severe) are seen in cattle that are positive for Babesia bovis on blood smear, however this has yet to be proven in any scientific arena. Outspoken red discolouration of the grey matter on post-mortem further strengthens suspicion of cerebral babesiosis. Diagnosis is confirmed post-mortem by observation of babesia infected erythrocytes sludged in the cerebral cortical capilaries in a brain smear.
and clindamycin
has been used, but is often poorly tolerated; recent evidence suggests that a regimen of atovaquone
and azithromycin
can be equally effective. In life-threatening cases, exchange transfusion is performed. In this procedure, the infected red blood cells are removed and replaced with fresh ones.
Veterinary treatment of Babesiosis does not normally use antibiotics. In animals diminazen (Berenil), imidocarb
or trypan blue
would be the drugs of choice for treatment of Babesia canis rossi (Dogs in Africa), Babesia bovis, and Babesia bigemina (cattle in Southern Africa).
There is a vaccine that is effective against Babesia canis canis (dogs in the mediterranean region) but this is ineffective against Babesia canis rossi. Babesia imitans causes a mild form of the disease that frequently resolves without treatment (dogs in South East Asia).
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
parasitic disease
Parasitic disease
A parasitic disease is an infectious disease caused or transmitted by a parasite. Many parasites do not cause diseases. Parasitic diseases can affect practically all living organisms, including plants and mammals...
caused by infection with Babesia
Babesia
Babesia is a protozoan parasite of the blood that causes a hemolytic disease known as Babesiosis. There are over 100 species of Babesia identified; however only a handful have been documented as pathogenic in humans....
, a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
l piroplasms
Piroplasmida
Piroplasms are protozoan parasite of the phylum Apicomplexa. They divide by binary fission and as sporozoan parasites they possess sexual and asexual phases...
. After trypanosome
Trypanosoma
Trypanosoma is a genus of kinetoplastids , a monophyletic group of unicellular parasitic flagellate protozoa. The name is derived from the Greek trypano and soma because of their corkscrew-like motion. All trypanosomes are heteroxenous and are transmitted via a vector...
s, Babesia are thought to be the second most common blood parasites of mammals and they can have a major impact on health of domestic animals in areas without severe winters. Human babesiosis is uncommon, but reported cases have risen recently because of expanded medical awareness.
Terminology
The disease is named for the genus of the causative organism, which was named after the Romanian bacteriologist Victor BabeşVictor Babes
Victor Babeș was a Romanian physician, biologist, and one of the earliest bacteriologists. He made early and significant contributions to the study of rabies, leprosy, diphtheria, tuberculosis, and other infectious diseases....
. Equine
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
babesiosis is also known as piroplasmosis (from the Latin piro, meaning pear
Pear
The pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
+ German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
plasma, a thing formed).
Epidemiology
Babesiosis is a vector-borne illness usually transmitted by Ixodes scapularisIxodes scapularis
Ixodes scapularis is commonly known as the deer tick or blacklegged tick , and in some parts of the USA as the bear tick. It is a hard-bodied tick of the eastern and northern Midwestern United States...
tick
Tick
Ticks are small arachnids in the order Ixodida, along with mites, constitute the subclass Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and sometimes reptiles and amphibians...
s. Babesia microti uses the same tick vector as Lyme disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...
and Ehrlichiosis
Ehrlichiosis
Ehrlichiosis is a tick-borne disease of dogs usually caused by the organism Ehrlichia canis. Ehrlichia canis is the pathogen of animals. Humans can become infected by E. canis and other species after tick exposure. German Shepherd dogs are thought to be particularly affected by the disease, other...
, and may occur in conjunction with these other diseases. The organism can also be transmitted by blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
.
In North America, the disease is primarily found in eastern Long Island
Long Island
Long Island is an island located in the southeast part of the U.S. state of New York, just east of Manhattan. Stretching northeast into the Atlantic Ocean, Long Island contains four counties, two of which are boroughs of New York City , and two of which are mainly suburban...
, Fire Island, Nantucket Island and Martha's Vineyard
Martha's Vineyard
Martha's Vineyard is an island located south of Cape Cod in Massachusetts, known for being an affluent summer colony....
off of the coast of Massachusetts. More generally it can be found in the northern midwestern and New England states.
It is sometimes called "The Malaria of The Northeast." Cases of babesiosis have been reported in a wide range of European countries. Disease in Europe is usually due to infection with Babesia divergens
Babesia divergens
Babesia divergens is an intraerythrocytic protozoan parasite, transmitted by the tick Ixodes ricinus. It is the main agent of bovine babesiosis, or "redwater fever", in Europe. Young cattle are less susceptible...
, while in the United States Babesia microti and Babesia duncani are the species most commonly associated with human disease. Babesiosis has also been observed in Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
.
Babesiosis has emerged in Lower Hudson Valley, New York since 2001.
Symptoms and signs
Most cases of Babesia infection are asymptomatic but can include mild fevers and diarrhea. The symptoms are often unnoticed or unexplained. In more severe cases, there are symptoms similar to malariaMalaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
, with fevers up to 40.5°C (105°F), shaking chills, and severe anemia (hemolytic anemia). Organ failure may follow including adult respiratory distress syndrome. Severe cases occur mostly in people who have had their spleen removed surgically
Splenectomy
A splenectomy is a surgical procedure that partially or completely removes the spleen.-Indications:The spleen, similar in structure to a large lymph node, acts as a blood filter. Current knowledge of its purpose includes the removal of old red blood cells and platelets, and the detection and fight...
. Severe cases are also more likely to occur in the very young, very old, and persons with immunodeficiency
Immunodeficiency
Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
, such as HIV/AIDS patients.
A reported increase in babesiosis diagnoses in the 2000s is thought to be caused by more widespread testing and higher numbers of people with immunodeficiencies coming in contact with ticks, the disease vector. Little is known about the occurrence of Babesia species in malaria-endemic
Endemic (epidemiology)
In epidemiology, an infection is said to be endemic in a population when that infection is maintained in the population without the need for external inputs. For example, chickenpox is endemic in the UK, but malaria is not...
areas, where Babesia can easily be misdiagnosed as Plasmodium
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
.
Pathophysiology
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s, where they can be seen as cross-shaped inclusions (4 merozoites asexually budding but attached together forming a structure looking like a "Maltese Cross
Maltese cross
The Maltese cross, also known as the Amalfi cross, is identified as the symbol of an order of Christian warriors known as the Knights Hospitaller or Knights of Malta and through them came to be identified with the Mediterranean island of Malta and is one of the National symbols of Malta...
") and cause hemolytic anemia
Hemolytic anemia
Hemolytic anemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells , either in the blood vessels or elsewhere in the human body . It has numerous possible causes, ranging from relatively harmless to life-threatening...
, quite similar to malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
.
Note that unlike the Plasmodium
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
parasites that cause malaria, Babesia species lack an exo-erythrocytic phase, so the liver is usually not affected.
In animals Babesia canis rossi, Babesia bigemina, and Babesia bovis
Babesia bovis
Babesia bovis is a single-celled protozoan parasite of cattle which occasionally infects humans. It is a member of the phylum Apicomplexa, which also includes the malaria parasite. The disease it and other members of the genus Babesia causes is a hemolytic anemia known as Babesiosis and...
cause particularly severe forms of the disease that include a severe haemolytic anaemia, with positive erythrocyte-in-saline-agglutination test indicating an immune mediated component to the haemolysis. Common sequelae include haemoglobinuria "red-water", disseminated intravascular coaguation (DIC) and "cerebral babesiosis" caused by sludging of erythrocytes in cerebral capillaries.
In the Bovine species, the organism causes a hemolytic anemia. Due to this the animal will show pale mucus membranes initially. As the levels of billirubin (a byproduct of red blood cell lysis) continue to increase, there will be a yellowing of the visible mucus membranes (icterus) due to the failure of the liver to metabolise the excess bilirubin. Hemoglobinuria will be seen due to excretion of red blood cell lysis by-products via the kidneys. Fever of 40.5 °C (104.9 °F) develops due to release of inflammatory by-products.
Diagnosis
A high index of suspicion is necessary to diagnose babesiosis. Babesiosis develops only in patients who live in or travel to an endemic area or receive a contaminated blood transfusionBlood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
within the preceding 9 weeks, so this aspect of the medical history is vital. Babesiosis may be suspected when a person with such an exposure history develops persistent fevers and hemolytic anemia. The definitive diagnostic test for babesiosis is the identification of parasites on a Giemsa-stained
Giemsa stain
Giemsa stain, named after Gustav Giemsa, an early German microbiologist, is used in cytogenetics and for the histopathological diagnosis of malaria and other parasites.-Uses:...
thin blood smear
Blood film
A blood film or peripheral blood smear is a thin layer of blood smeared on a microscope slide and then stained in such a way to allow the various blood cells to be examined microscopically...
. So-called "Maltese cross formations" on the blood film are essentially diagnostic of babesiosis, since they are not seen in malaria, the primary differential diagnosis. Careful examination of multiple blood smears may be necessary, since Babesia may infect less than 1% of circulating red blood cells and thus be easily overlooked.
Serologic testing
Serology
Serology is the scientific study of blood serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum...
for antibodies
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
against Babesia (both IgG and IgM
IGM
IGM as an acronym or abbreviation can refer to:* Immunoglobulin M , the primary antibody against A and B antigens on red blood cells* International Grandmaster, a chess ranking* intergalactic medium* Intragroup medium - see: Intracluster medium...
) can detect low-level infection in cases where there is a high clinical suspicion but negative blood film examinations. Serology is also useful for differentiating babesiosis from malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
in cases where people are at risk for both infections. Since detectable antibody responses require approximately one week after infection to develop, serologic testing may be falsely negative early in the disease course.
A polymerase chain reaction
Polymerase chain reaction
The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....
(PCR) test has been developed for the detection of Babesia from the peripheral blood. PCR may be at least as sensitive and specific
Sensitivity and specificity
Sensitivity and specificity are statistical measures of the performance of a binary classification test, also known in statistics as classification function. Sensitivity measures the proportion of actual positives which are correctly identified as such Sensitivity and specificity are statistical...
as blood film examination in diagnosing babesiosis, though it is also significantly more expensive. Most often, PCR testing is used in conjunction with blood film examination and possibly serologic testing
Serology
Serology is the scientific study of blood serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum...
.
Other laboratory findings include decreased numbers of red blood cells and platelets on complete blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
.
In animals Babesiosis is suspected by observation of clinical signs (haemoglobinuria and anaemia) in animals in endemic areas. Diagnosis is confirmed by observation of merozoites on thin film blood smear examined at maximum magnification under oil using Romonovski stains (methylene blue and eosin). This is a routine part of the veterinary examination of dogs and ruminants in regions where babesiosis is endemic.
Babesia canis and Babesia bigemina are "large babesias" that form paired merozoites in the erythrocytes , commonly described as resembling "two pears hanging together", rather than the "Maltese Cross" of the "small babesias". Their merozoites are approximately twice the size of small babesias.
Cerebral babesiosis is suspected in-vivo when neurological signs (often severe) are seen in cattle that are positive for Babesia bovis on blood smear, however this has yet to be proven in any scientific arena. Outspoken red discolouration of the grey matter on post-mortem further strengthens suspicion of cerebral babesiosis. Diagnosis is confirmed post-mortem by observation of babesia infected erythrocytes sludged in the cerebral cortical capilaries in a brain smear.
Treatment
Most cases of babesiosis resolve without any specific treatment. For ill patients, treatment is usually a two-drug regimen. The regimen of quinineQuinine
Quinine is a natural white crystalline alkaloid having antipyretic , antimalarial, analgesic , anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine which, unlike quinine, is an anti-arrhythmic...
and clindamycin
Clindamycin
Clindamycin rINN is a lincosamide antibiotic. It is usually used to treat infections with anaerobic bacteria but can also be used to treat some protozoal diseases, such as malaria...
has been used, but is often poorly tolerated; recent evidence suggests that a regimen of atovaquone
Atovaquone
Atovaquone is a chemical compound that belongs to the class of naphthalenes. Atovaquone is a hydroxy-1,4-naphthoquinone, an analog of ubiquinone, with antipneumocystic activity. Its average wholesale price is about US$2.13 per standard 250 mg. tablet...
and azithromycin
Azithromycin
Azithromycin is an azalide, a subclass of macrolide antibiotics. Azithromycin is one of the world's best-selling antibiotics...
can be equally effective. In life-threatening cases, exchange transfusion is performed. In this procedure, the infected red blood cells are removed and replaced with fresh ones.
Veterinary treatment of Babesiosis does not normally use antibiotics. In animals diminazen (Berenil), imidocarb
Imidocarb
Imidocarb is a urea derivative used in veterinary medicine as an antiprotozoal agent for the treatment of infection with Babesia and other parasites....
or trypan blue
Trypan blue
Trypan blue is a vital stain used to selectively colour dead tissues or cells blue. It is a diazo dye.Live cells or tissues with intact cell membranes are not coloured. Since cells are very selective in the compounds that pass through the membrane, in a viable cell trypan blue is not absorbed;...
would be the drugs of choice for treatment of Babesia canis rossi (Dogs in Africa), Babesia bovis, and Babesia bigemina (cattle in Southern Africa).
There is a vaccine that is effective against Babesia canis canis (dogs in the mediterranean region) but this is ineffective against Babesia canis rossi. Babesia imitans causes a mild form of the disease that frequently resolves without treatment (dogs in South East Asia).
External links
- http://www.dpd.cdc.gov/dpdx/HTML/Babesiosis.htm - Public domainPublic domainWorks are in the public domain if the intellectual property rights have expired, if the intellectual property rights are forfeited, or if they are not covered by intellectual property rights at all...
source from which the first version of this article was derived. - Babesiosis - Homer MJ, Aguilar-Delfin, I, et al., Clinical Microbiology Reviews, July 2000, p. 451-469, Vol. 13, No. 3
- "Babesiosis: Overview" The Merck Veterinary Manual