Abstract
Filariasis is a major public health hazard in tropical and subtropical countries and is endemic among the Indian population. Asymptomatic microfilariaemia, elephantiasis, acute adenolymphangitis, hydrocoele and chronic lymphatic disease are its common manifestations. We hereby report a case of microfilaria found in the bone marrow presenting as pancytopenia. There was no classical feature of elephantiasis or lymphoedema present.
Case report
A 32-year-old woman, resident in northern India, presented with the following symptoms of three months' duration: generalised weakness; lethargy; fatigue; and breathlessness on moderate exertion. She had a weight loss of 5 kg during this period. There was no history of smoking, alcohol consumption or prolonged use of drugs.
On examination, she was moderately pale. She had a grade II ejection systolic murmur heard in the left second intercostal space, but the remaining examination was within normal limits.
Laboratory tests revealed a pancytopenia (Hb 60 g/L, total leucocyte count of 3.3.109/m3 and platelet count of 65.109/m3). Peripheral smear showed normocytes, some microcytes and normochromic red blood cell morphology. The erythrocyte sedimentation rate was 45 mm/h. Urine routine and microscopy, liver and renal function tests were within normal limits. Serum lactase dehydrogenase, level of vitamin B12 and levels of folic acid were within normal limits. The Coomb's tests (direct and indirect) were negative. Serology for viral hepatitis and HIV was likewise negative, as were mantoux and antinuclear antibody tests. No abnormality was detected on chest radiography or computed tomography (CT) thoraco-abdominal scanning. Bone marrow aspiration revealed microfilariae of Wuchereria bancrofti with tail ends free from nuclei in the buffy coat of peripheral smear (Figure 1).
Bone marrow aspiration smear showing microfilariae of Wuchereria bancrofti with tail end free from nuclei in the buffy coat of peripheral smear (Giemsa stain, 100 X).
A single dose of albendazole (400 mg) and diethyl carbamazine citrate (6 mg/kg) daily for 12 days were administered. A total of 4 units of packed cells and 2 units of platelet-rich plasma were transfused during her hospital stay. On review after one month, she was totally asymptomatic with normal blood counts and haemoglobin levels.
Discussion
The exact mechanism of the transit of microfilariae to extravascular tissue spaces is not completely elucidated. Possible hypothesis include microfilariae crossing the vessel wall by their boring ability to reach the tissue spaces. 1 In filariasis, peripheral blood eosinophilia is a common haematological finding, but paradoxically, in a majority of reported cases, microfilariae were demonstrated in the bone marrow in which eosinophilia was absent.1,2 In view of pancytopenia and relative decrease of myeloid cells and megakaryocytes in bone marrow, it is possible that liberation of some toxic metabolites by growing larvae, i.e. microfilariae, might cause toxic bone marrow suppression. 3
There are very few reported cases of pancytopenia, hypoplastic or aplastic anaemia as a presenting feature of filariasis:2,4–6 among six cases where microfilariae were found in bone marrow aspirates, five had bone marrow hypoplasia or aplasia. In two of those cases, the aetiology was considered idiopathic. In another case, microfilariae were present in the bone marrow but not in the peripheral blood. Thus, any patient with pancytopenia in a region endemic to filaria should also be evaluated with bone marrow aspiration for microfilariasis, especially as this is eminently treatable.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
