Tuesday, July 22, 2014

Tick borne diseases for the nephrologist - Babesiosis

The following few posts are a summary of tick borne illnesses that can cause renal failure and/or electrolyte problems. 

First identified on Nantucket Island in 1969 and was initially know as Nantucket fever.

Endemic areas.
CDC map. Reported cases in 2012
Cases have been reported in Europe (Croatia, France, Great Britain, Ireland, Portugal, Spain, Sweden, Switzerland)(Babesia divergens).

The tick.
Ixodes scapularis. The Blacklegged tick.

The pathogen.
Babesia microti and B. duncani (USA). B divergens (Europe). Protozoan parasites infecting red blood cells
Humans are not a natural host. Infection by blood transfusion has been reported.

Incubation period 1 – 9 weeks

Clinical features.
Fever, chills, sweats, Malaise, fatigue, Myalgia, arthralgia, headache, Gastrointestinal symptoms, such as anorexia and nausea (less common: abdominal pain, vomiting)
Dark urine
Less common: cough, sore throat, emotional lability, depression, photophobia, conjunctival injection
Mild splenomegaly, mild hepatomegaly, or jaundice may occur in some patients

Lab features
Haemolytic anemia, thrombocytopenia, renal failure, transaminitis.

Diagnosis - Light microscopy of blood cells, serology and PCR for B. microti or B. duncani

Treatment - Atovaquone plus azithromycin or quinine plus clindamycin orally for 7 to 10 days.
Atovaquone plus azithromycin is preferred as this combination is better tolerated.

The source for this review is mainly from the CDC website as well as various references cited in the posts. The tick pictures provided may differ from what might be found on a bitten human. Ticks become larger and engorged after feeding and will look different.

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