ABSTRACT
Filarial fever should always be kept in mind as a key differential diagnosis of febrile illnesses in endemic areas.
Keywords: filaria, microfilaria, peripheral blood smear, wet‐mount microscopy
A 74‐year‐old man residing in a coastal town of Eastern India presented with non‐productive cough, chest pain, fever, tingling sensation and body ache for the last 5 days. A complete hemogram revealed a highly elevated differential eosinophil count of 28.2%, an extremely high absolute eosinophil count of 3.62 × 109/L and a high serum Immunoglobulin E level of 697.27 IU/mL. A wet‐mount microscopic examination of the centrifuged whole blood specimen demonstrated microfilaria dancing amongst the red blood cells (Video 1 and Figure 1A) identified as the filarial species Wuchereria bancrofti (with the pointed tail‐end free of nuclei) on Giemsa stain (Figure 1B). A rapid immune‐chromatographic assay was also positive for W. bancrofti antigen. A diagnosis of acute filarial fever was made and the patient was advised a complete course of diethylcarbamazine along with albendazole. Follow‐up telephonic call after 3 months of presentation revealed dramatic improvement with complete subsidence of all symptoms within 1 month of completing the medications, with no further complaints even after 6 months. The filarial worm W. bancrofti is the causative agent of lymphatic filariasis and transmitted through the bite of an infected mosquito, mostly of the genera Culex, Anopheles, Aedes, and Mansonia depending on the geographic location [1]. Acute episodes often present as lymphangitis, lymphadenitis and lymphoedema while chronic infections may result in hydrocele and elephantiasis. The larvae, known as microfilaria (born as tiny juvenile young babies in an ovo‐viviparous mode), can sometimes be seen wriggling in the peripheral blood specimen similar to their parental counterparts in the dilated lymphatic channels, as observed in the current case [2]. In case of W. bancrofti, rapid antigen tests (that can be performed on blood samples collected at any period of time) are more sensitive for detection of filariasis infection compared to microscopic tests that detect nocturnally periodic microfilariae in samples collected at night. Filarial fever should always be kept in mind as a key differential diagnosis of febrile illnesses in endemic areas.
VIDEO 1.
Wet‐mount microscopy showing microfilaria dancing amongst the red blood cells (400×). Video content can be viewed at https://onlinelibrary.wiley.com/doi/10.1002/ccr3.72444.
FIGURE 1.
Microfilaria observed on (A) wet‐mount microscopy (400×) and (B) Giemsa‐stained peripheral blood smear, with tail‐end free of nuclei (1000×).
Author Contributions
Srujana Mohanty: conceptualization, data curation, formal analysis, investigation, methodology, project administration, resources, software, supervision, validation, visualization, writing – original draft, writing – review and editing. Mohd Nadeem: data curation, formal analysis, investigation, methodology, software, writing – review and editing. Monalisa Dey: data curation, formal analysis, investigation, methodology, visualization, writing – review and editing. Prasanta Raghab Mohapatra: data curation, resources, writing – review and editing.
Funding
The authors have nothing to report.
Consent
A written informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy.
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgments
We acknowledge the technical support provided by Mr. Pradyumna Sahoo for this work, especially in the preparation of the wet‐mount and performing the Giemsa staining.
Data Availability Statement
The data that support the findings of this study are available within the article.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available within the article.