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Table of Contents
Year : 2022  |  Volume : 18  |  Issue : 3  |  Page : 100-101

An unusual presentation of filariasis as pyrexia of unknown origin: Case report

1 Department of General Medicine, Amrita Institute of Medical Sciences, Kochi, Kerala, India
2 Department of Gastroenterology, Amrita Institute of Medical Sciences, Kochi, Kerala, India
3 Department of Geriatric Medicine, Amrita Institute of Medical Sciences, Kochi, Kerala, India
4 Department of General Medicine, Armed Forces Medical College, Pune, Maharashtra, India
5 Department of Clinical Microbiology, Aster Medcity, Kochi, Kerala, India

Date of Submission22-Jul-2022
Date of Acceptance09-Sep-2022
Date of Web Publication13-Dec-2022

Correspondence Address:
Nimitha K Mohan
Department of Clinical Microbiology, Aster Medcity, Kochi, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/AMJM.AMJM_27_22

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Filariasis is a common, yet neglected tropical disease and has a wide spectrum of clinical presentations. It is particularly endemic in certain regions of India. We report this case due to the rare isolation of Microfilariae from the bone marrow aspirate preparation. Here, we report a patient with a history of pyrexia of unknown origin (PUO). The relevant investigations done failed to identify the causative organism. After ruling out routine causes of fever, bone marrow analysis was done and it revealed Microfilariae in the aspirate. The surprising aspect of the case is the absence of eosinophilia in the complete blood picture. The patient was treated with anthelmintics and the fever subsided within 48 h. This case emphasizes the importance of bone marrow study in patients with PUO and the presence of microfilaria in the absence of eosinophilia.

Keywords: Bone marrow, microfilaria, PUO

How to cite this article:
Hakeem SC, Valsan A, Srivatsa N, Shrutiraaj KA, Khajuria SP, Mohan NK, Kohli K. An unusual presentation of filariasis as pyrexia of unknown origin: Case report. Amrita J Med 2022;18:100-1

How to cite this URL:
Hakeem SC, Valsan A, Srivatsa N, Shrutiraaj KA, Khajuria SP, Mohan NK, Kohli K. An unusual presentation of filariasis as pyrexia of unknown origin: Case report. Amrita J Med [serial online] 2022 [cited 2023 Jun 4];18:100-1. Available from: https://ajmonline.org.in/text.asp?2022/18/3/100/363501

  Introduction Top

Filariasis is one of the major public health problems in tropical countries, including India. It is caused by parasitic nematodes belonging to the superfamily Filarioidea. It is mainly caused by Wuchereria bancrofti, Brugia malayi, and B. timori. Adult worms live in the lymphatic system, cutaneous tissues, or body cavity of humans and are transmitted through vectors. Wuchereria bancrofti and B. malayi are responsible for cases of lymphatic filariasis (LF) in India, with the former being responsible for 99.4% of the cases. Diagnosis of filariasis is based on the demonstration of microfilaria in peripheral blood or in body fluids.[1] The demonstration of Microfilariae in bone marrow aspirate smears is unusual.[2] Hence, we report a case of filariasis which presented to us as a case of pyrexia of unknown origin (PUO) that was diagnosed based on demonstration of microfilaria in bone marrow aspirate.

  Case Presentation Top

A 23-year-old boy, resident of Chapra district of Bihar state, presented to our hospital with moderate-to-high-grade intermittent fever of 3 weeks duration. He was treated on outpatient department basis for the same at a peripheral hospital and was referred to our center in view of non-improvement. In spite of broad-spectrum antibiotics and supportive measures, his fever persisted. He also complained of sore throat, global headache along with generalized malaise. On examination, he was moderately built and had bilateral axillary lymphadenopathy. Oral cavity examination revealed an aphthous ulcer over the anterior faucial pillar with congestion of the posterior pharyngeal wall. The rest of the systemic examination revealed no abnormality. Routine investigations were essentially normal. His blood cultures were sterile. Mantoux test was negative. His serum angiotensin-converting enzyme levels were low. fine needle aspiration cytology from the axillary lymph node was reported as reactive hyperplasia. As a workup for PUO, bone marrow aspiration and cytology were done, which revealed a reactive cellular marrow with Microfilariae incidentally detected in the smear.

The patient was administered antifilarialial therapy consisting of diethylcarbamazine 6 mg/kg/day to which he responded dramatically. His fever subsided in 48 h and thereafter had an uneventful recovery.

  Discussion Top

The clinical spectrum of LF ranges from asymptomatic microfilaraemia to the later stages of acute, chronic, and occult clinical manifestations such as lymphedema, chyluria, hydrocele, and filarial granulomata to name a few. Man is the natural host and both genders, as well as all age groups, can be affected. Culex mosquito is the vector and intermediate host. The larvae enter through the skin and reach lymph nodes via the lymphatic channel. They mature and produce new larvae in 15–18 months. Through the thoracic duct, these then enter the venous system and reach the peripheral circulation. The exact mechanism by which they reach bone marrow is not known, lymphatic obstruction and subsequent extravasation have been postulated as possible mechanisms.[3] Pradhan et al.[4] first reported the presence of microfilaria in bone marrow in seven patients with asymptomatic filariasis. The classical presentation of filariasis is often missing in patients in whom the parasite has been shown in bone marrow. The absence of peripheral blood eosinophilia in such patients has been a finding worth consideration as reported in various case reports[5],[6] and the same was observed in our case also. Bone marrow picture in cases of Microfilariae infection may vary from hypoplastic marrow or aplastic marrow to hyperplastic marrow with a normoblastic or a megaloblastic maturation. In our case, it was a normal cellular marrow. Treatment is mainly diethylcarbamazine 6 mg/kg in absence of onchocerciasis or loiasis. Doxycycline (200 mg/day for 4–6 weeks) can also be used as an alternative first-line therapy in cases where diethylcarbamazine is not available or contraindicated. Diethylcarbamazine should not be used for onchocerciasis or loiasis in view of severe adverse reactions.

PUO is one of the most challenging cases for physicians. In tropical countries, the possibility of vector-borne diseases should always be kept as a differential for PUO. This case highlights the uncommon presentation of a common disease. Bone marrow biopsy was the clinching investigation to confirm the diagnosis. This case highlights the importance of bone marrow biopsy in the evaluation of PUO.

  Conclusions Top

Filariasis is an uncommon cause of PUO; however, this should be considered in residents from an endemic region. Low yield of peripheral smear in detecting microfilaria, absence of peripheral blood eosinophilia leads to low suspicion and delayed diagnosis in these cases. This index case highlights importance of bone marrow study in pyrexia evaluation.

Financial support and sponsorship

Not applicable.

Conflicts of interest

There are no conflicts of interest.

  References Top

Adhikari A Incidental demonstration of filaria saved a child from pyrexia of unknown origin: Report of an interesting case. Indian J Health Sci2015;8:153-5.  Back to cited text no. 1
Tummidi S, Balakrishna P, Gupta Y Microfilariae in a bone marrow aspirate. BMC Res Notes 2016 9:256.  Back to cited text no. 2
Walter A, Krishnaswami H, Cariappa A Microfilariae of Wuchereria bancrofti in cytologic smears. Acta Cytol 1983; 27:432-6.  Back to cited text no. 3
Pradhan S, Lahiri VL, Elhence BR, Singh KN Microfilaria of Wuchereria bancrofti in bone marrow smear. Am J Trop Med Hyg 1976;25:199-200.  Back to cited text no. 4
Sharma S, Rawat A, Chowhan A Microfilariae in bone marrow aspiration smears, correlation with marrow hypoplasia: A report of six cases. Indian J Pathol Microbiol 2006;49:566-8.  Back to cited text no. 5
Debanjali S, Sumantro M, Tony E, Arijit N, Kaushik B, Sattik S, et al. Filariasis presenting with pancytopenia diagnosed by microfilaria in bone marrow aspirate - report of a rare entity from India. Int J Med Sci Public Health 2014;3:638-9.  Back to cited text no. 6


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