Babesiosis is an infectious tick-borne caused by protozoa of the genus Babesia.
The symptoms manifested in cases of babesiosis are similar to symptoms of malaria. The extent of the symptoms depends on the extent of RBC destruction due to the parasite. The range can be from no overt symptoms to severe haemolysis which can be fatal. The affected patients may give a history of travel to the endemic areas. In patients with subclinical infection, there may be spontaneous development of the symptoms after splenectomy or after immunosuppressive therapy. Patients who are healthy and have a strong immune system, may remain asymptomatic or may suffer from mild to moderate symptoms.
The incubation period for patients bitten by the infected tick is about one to four weeks, while the incubation period for patients affected due to contaminated blood transfusion is about one week to six months. The most common symptoms include high grade fever ranging up to 40.9 °C (105.6 °F). In a study of 139 patients of babesiosis hospitalised at New York, the commonest symptoms noted were – fatigue/malaise/weakness (91%), fever (91%), shaking chills (77%), diaphoresis (69%) . Splenomegaly is also detected. Along with fever there is severe malaise, fatigue, severe chills, sweating, anorexia, nausea, vomiting, weight loss, headache, myalgia, arthralgia, cough, sore throat, photophobia and depression. Haemoglobinuria is also one of the accompanying symptoms. The fatigue continues for several months even after other symptoms have subsided.
Immuno-suppressed patients, patients with HIV infection, the elderly patients and who have undergone splenectomy suffer from more severe and prolonged infections with relapses needing frequent hospitalisation.
The patients can experience certain complications which include disseminated intravascular coagulopathy and acute respiratory distress syndrome. Other complications may include liver, kidney or congestive heart failure, coma and death. Asplenic patients have a more prolonged disease course, higher morbidity and mortality and more overwhelming infection . Shock, relapse and spontaneous splenic rupture too have been observed .
One must suspect babesiosis infection in patients with fever of unknown origin who reside in or have recently travelled to or from an endemic area or who have recently received a blood transfusion. The diagnosis detection depends on the extent of the infection and on the skills of the laboratory technician.
In patients who are asymptomatic the laboratory findings may not be conclusive. Laboratory testing includes a complete blood count (CBC). It may reveal haemolytic anaemia, lymphopenia, and thrombocytopenia. The erythrocyte sedimentation rate (ESR) may be increased.
Peripheral blood smears can be used to diagnose Babesiosis by microscopic examination of Giemsa-stained or Wright-stained blood smears which reveal the different forms of parasites in the RBCs. In patients suffering from an asymptomatic infection, the smear results may not be positive.
Serum chemistry shows elevated levels of serum creatinine and blood urea nitrogen. Liver function tests (LFTs) show elevated levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatise. It also reveals high bilirubin levels and reduced haptoglobin level1. Elevated Lactate dehydrogenase (LDH) levels reveal the extent of the severity of the infection.
Serological testing which includes Indirect immunofluorescent Antibody (IFA) assay of immunoglobulin M (IgM) or immunoglobulin G (IgG) can also be useful in confirming the diagnosis. However, Immunoblot antibody testing has greater sensitivity and specificity as compared to IFA testing.
Hamster inoculation includes intraperitoneal inoculation of Ethylene Diamine Tertraacetic Acid (EDTA) whole blood from the patient into the peritoneum of a hamster followed by antibody analysis of the animal blood. This test helps in diagnosis when above mentioned tests are non-conclusive.
Polymerase chain reaction (PCR) can help in confirming the diagnosis by detecting Babesia DNA in the patient's blood. A study found that PCR could detect babesial DNA as late as 27 months after an untreated infection . PCR testing is more specific as compared with peripheral smear evaluation and hamster inoculation.
Urinalysis may reveal haemoglobinuria.
The goal of medical therapy is to reduce morbidity and mortality, eradicate infection and prevent sequelae. Antimicrobial agents like atovaquone and azithromycin are administered to treat mild to moderate infection of babesiosis.
In a prospective study, it was noted that atovaquone plus azithromycin are as effective as clindamycin plus quinine in giving clinical relief and reducing parasitemia . Treatment of severe infection includes oral quinine and intravenous clindamycin.
Doxycycline too has been used along with clindamycin and azithromycin in patients who were allergic to cinchone derived quinine. Parasitemia may continue to persist even after treatment with either drug regimen.
The prognosis of the disease is dependent on the species of the parasite and the general immune status of the patient. Most patients with a strong immune system have excellent recovery.
Animals that act as reservoirs are horses, cattle and cats. Such cases have often been reported where the blood donor resided or travelled to an endemic area  . The protozoan can easily be transmitted through transfusion of contaminated blood or blood products. Very rarely, it can be transmitted through the placenta from an infected mother to the foetus.
Prevalence of Babesiosis all over the world is not clearly known. It is commonly reported in The United States of America. Babesiosis is less common in other areas of the world like in Europe, Asia, Africa, Australia etc.
Since most patients who are infected with babesiosis are asymptomatic, the actual prevalence of the illness is unknown. Babesiosis is more common in asplenic patients, immune-compromised patients and elderly patients.
Babesiosis is transmitted from animals to humans by tick bite.
The ticks have 3 phases i.e. larva, nymph, and adult. Each of these feed on a blood meal to develop into the next phase. The larva and nymph feed on rodents while an adult feeds on other animals.
The signs and symptoms depend on RBC parasitemia. During the feed, the tick ingests Babesia from the host animal. Then these multiply in the gut wall of the tick and are stored in the salivary glands. These are then inoculated in the new host when the ticks feed on the host.
Once in the blood stream, the parasite infects the RBCs producing trophozoites. These then divide to form merozoites. While leaving the RBC, they damage the RBC membrane. This leads to decreased RBC conformability and increased RBC adherence causing pulmonary edema and acute respiratory distress syndrome in severe cases.
Haemolytic RBCs cause capillary blockage or micro-vascular stasis affecting the liver, spleen, kidneys and the CNS. Haemolytic anaemia is produced due to the rapid RBC destruction. Spleen aids in removal of the damaged RBCs. This explains the high occurrence and increased severity of this disease in asplenic patients .
There are no guidelines for prevention of Babesiosis.
Babesiosis is caused by a protozoa Babesia. It is a tick-borne malaria-like parasitic illness that infects the red blood cells. The symptoms can vary from no overt illness to highly fatal consequences.
It is a zoonotic disease that is transmitted from animals to humans by ticks. It can also be caused due to transmission of contaminated blood. The severity of the disease is higher in patients who are immuno-compromised or patients with HIV infection.
The incidence of the disease is high in patients who have undergone splenectomy. The signs and symptoms of this disease depend on the extent of RBC destruction due to the parasite. It takes about one to four weeks for the symptoms to appear in patients bitten by the infected tick. In cases where the disease is caused due to blood transfusion it may take one week to six months for the symptoms to appear.
The most common symptom is high grade fever ranging up to 40.9 °C that is 105.6 °F. The parasite enters the RBCs causing severe destruction. This leads to haemolytic anaemia. The damaged RBCs are trapped by the spleen. Hence, splenomegaly is also detected.
Along with fever there is severe malaise, fatigue, severe chills, sweating, anorexia, nausea, vomiting, weight loss, headache, muscle and joint pains, cough, sore throat, photophobia and depression. Blood in urine is also one of the symptoms. The fatigue continues for several months even after the symptoms have healed.
Complications due to Babesiosis are disseminated intravascular coagulopathy and acute respiratory distress syndrome.
Elevated Lactate dehydrogenase (LDH) and a well stained peripheral blood help in the diagnosis of the disease. Polymerase Chain Reaction Assay is a specific test for the diagnosis.
Patients with a strong immune system experience a complete recovery from the disease as compared to patients who are immuno-compromised.