Babesia: Introduction, Morphology, Pathogenecity, Laboratory Diagnosis and Treatment
Introduction of Babesia
Babesiosis is caused by microscopic parasites, Babesia infects red blood cells and is spread by ticks(Ixodes scapularis). There are more than 100 species of Babesia, among them common are –
B. microti,
B. bovis ,
B. divergens.
Named after Babes who first observed in the blood of cattle and sheep. Tick-borne disease is most common in the USA and Europe.
Scientific classification
- Domain: Eukaryota
- (unranked): Diaphoretickes
- Clade: TSAR
- Clade: SAR
- Infrakingdom: Alveolata
- Phylum: Apicomplexa
- Class: Aconoidasida
- Order: Piroplasmida
- Family: Babesiidae
- Genus: Babesia
Habitat
Inside red blood cells (RBCs)
Morphology of Babesia
It has two forms and they are sporozoite and trophozoite.
Sporozoite: It is an infective form, found in ticks.
Trophozoites
- Oval and spindle-shaped having a size of 1 -5 µm.
- Small chromatin dot and scanty cytoplasm
Merozoites: They are oval or round present as pyriform bodies arranged in pairs or multiples of 2.
Life Cycle of Babesia
- Definitive host: Ixodes scapularis (tick)
- Intermediate host: Man and domestic animals
Pathogenicity: They can cause severe complications like-
- Acute tubular necrosis
- Pulmonary oedema
- Respiratory failure
Clinical features
Incubation period: 1 -4 weeks
- Fever
- Mild splenomegaly
- Anaemia
- Jaundice
- haemoglobinuria
Haematological
- Haemolytic anaemia
- WBC count;-normal or decreased
- Reticulocyte count:-increased
- Thrombocytopenia
- ESR:-increased
Risk factors of Babesiosis
Following are the risk factors-
- People without spleen
- weakened immune system
- Older adults, especially those with other health problems
Laboratory Diagnosis
- A thin and thick smear
- Stain: Leishman, Wrights and Giemsa
- Only ring form seen
Features
- Haemozoin and gametocyte are absent
- Merozoite arranged in tetrads or maltese cross form
Serodiagnosis: Immunofluorescence assay (IFA)
Molecular Test: PCR
Other Tests
- Serum protein electrophoresis:-poly clonalgammapathy
- Urine:-haemoglobinuria and proteinuria
- Haptoglobin:-decreased
Treatment
Babesia is a parasite that can not respond to antibiotics alone. Treatment requires antiparasitic drugs, such as those used for malaria and thus a combination of antimicrobial agents are used to treat them. Combination of clindamycin (600 mg 3 times daily) and oral quinine 20 mg/kg body weight daily for children; 650 mg 3-4 times daily for adults. Medication is for 7-10 days.
Keynotes
- Babesiosis often occurs at the same time as Lyme disease. The tick that carries the Lyme bacteria can also be infected with the Babesia parasite.
- Babesia microti is the most common strain to infect humans, according to the Centers for Disease Control and Prevention (CDC).
- Babesia is also called Nuttallia.
Further Readings
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4557164/
- https://www.healthline.com/health/babesia#transmission
- https://en.wikipedia.org/wiki/Babesia
- Atlas of Medical Helminthology and protozoology -4th edn -P.L. Chiodini, A.H. Moody, D.W. Manser
- Merkel and Voge’s medical parasitology-9th edition.
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- District laboratory practice in Tropical countries –Part-I.
By Monica Chesbrough. - Isenberg clinical microbiology procedures Handbook
2nd edition. Vol. 2 - Medical Parasitology by Abhay R. Satoskar, Gary L. Simon, Peter J. Hotez and Moriya Tsuji
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