Lymphatic filariasis: the importance of screening all peripheral blood smears in low power for detection of asymptomatic cases


  • Sneha P. Chavarkar Department of Pathology, MUHS, Nashik, Maharashtra, India



Filariasis, Low cost, Low power scanning, Peripheral blood smear


Lymphatic filariasis caused by the mosquitoborne, lymphatic-dwelling nematodes Wuchereria bancrofti and Brugia malayi is still a common tropical parasitic disease and 120 million people are affected in the world, of which two-third are in Asia. They cause high morbidity and mortality among humans. Irreversible “elephantiasis” is the major clinical manifestation for LF. Detection of microfilaria in peripheral blood is important. In addition to simple thick and thin blood smear tests, concentration techniques are used: mainly density gradient centrifugation, haemolysis and filtration of the blood through a polycarbonate membrane, which retains the parasite. Diagnosis has been revolutionized with the availability of circulating filarial antigen (CFA) tests which are easy to perform but are costly. Diethylcarbamazine (DEC) is the drug of choice for treating lymphatic filariasis. In the light of this information, hereby presenting a case series of 4 asymptomatic patients who were diagnosed with filariasis on peripheral blood smear examination. The article emphasizes the importance of low power scanning of every peripheral blood smear, especially when the laboratory is not facilitated with costly methods to detect microfilaria.


Denham DA, McGreevy PB. Brugian filariasis. Adv. Parasitol. 1977;17:243-308.

Arora VK, Gowrinath K. Pleural effusion due to lymphatic filariasis. Indian J Chest Dis Allied Sci. 1994;36:159-61.

Palumbo E. Filariasis: diagnosis, treatment and prevention. Acta Biomed. 2008;79:106-9.

Leeuwin RS. Microfilaremia in Surinamese living in Amsterdam. Trop. Geogr. Med. 1962;14:355-60.

Nanduri J, Kazura J. Clinical and laboratory aspects of filariasis. Clinical Microbiology Reviews. 1989;2(1):39-50.

Fernando SD, Rodrigo C, Rajapakse S. Current evidence on the use of antifilarial agents in the management of bancroftian filariasis. J Trop Med. 2011;2011:175941.

World Health Organization. Weekly Epidemiol Rep. 2012;37:345-56.

World Health Organization. Preparing and implementing a national plan to eliminate lymphatic filariasis. Geneva: WHO. 2000.

Addiss D. The global alliance to eliminate lymphatic filariasis. The 6th Meeting of the global alliance to eliminate lymphatic filariasis: a half-time review of lymphatic filariasis elimination and its integration with the control of other neglected tropical diseases. Parasit Vectors. 2010;3:100.

Sabesan S, Palaniyandi M, Das PK, Michael E. Mapping of lymphatic filariasis in India. Ann Trop Med Parasitol. 2000;94:591-606.

Freedman DO, de Almeida Filho PJ, Besh S, Maia e Silva MC, Braga C, Maciel A. Lymphoscintigraphic analysis of lymphatic abnormalities in symptomatic and asymptomatic human filariasis. J Inf Dis. 1994;170:927-33.

Rosenblatt JE. Laboratory diagnosis of infections due to blood and tissue parasites. Clin Infect Dis. 2009;49:1103-8.

John DT, Petri WA. "Wuchereria bancrofti." Medical Parasitology. 9th ed. St. Louis, Missouri: Saunders Elsevier. 2006:274-85.

Ottesen EA. "Filariases and tropical eosinophilia" in Tropical and Geographic Medicine (K.S. Warren and A.A.F. Mahmoud, eds). McGraw-Hill Book Co., New York. 1984;390-412.

Desowitz RS, Hitchcock JC. Hyperendemic bancroftian filariasis in the Kingdom of Tonga: the application of the membrane-filter technique to an age-stratified blood survey. Am. J. Trop. Med. Hyg. 1974;23:877-79.

Amaral F, Dreyer G, Figueredo-Silva J, Noroes J, Cavalcanti A, Samico SC, et al. Live adult worms detected by ultrasonography in human bancroftian filariasis.Am J Trop Med Hyg. 1994;50:735-57.

McCarthy J. Diagnosis of lymphatic filarial infection. In: Lymphatic Filariasis, ed. Nutman TB, Imperial College Press, London. 2000;127-41.

Weil G, Lammie PJ, Weiss N. The ICT filariasis test: A rapid format antigen test for diagnosis of bancrofitian filariasis. Parasitol Today. 1997;13:401-4.

McCarthy J. Diagnosis of lymphatic filarial infection. In: Lymphatic Filariasis, ed. Nutman TB, Imperial College Press, London. 2000;127-41.

Sharma S, Rawat A, Chowhan A. Microfilariae in bone marrow aspiration smears; their correlation with marrow hypoplasia: a report of six cases. Indian J Pathol Microbiol. 2006;49:566-68.

Pradhan S, Lahiri VL, Elhence BR, Singh KN. The microfilariae of Wuchereria bancrofti in bone marrow smears. Am J Trop Med Hyg. 1976;25:199-200.

Shenoi U, Pai RR, Pai U, Nandi GK, Adhikari P. Microfilariae in bone marrow aspiration smears. Acta Cytol. 1998;42:815-16.

Pal BK, Kulkarni S, Bhandari Y, Ganesh BB, Goswami K, Reddy MV. Lymphatic filariasis: a possible pathophysiological nexus with oxidative stress. Trans R Soc Trop Med Hyg. 2006;100:650-55.

Hemachandran M, Varma N, Varma S. Aplastic anaemia following a varicella infection with a coexistent microfilaraemia of Wuchereria bancrofti- a case report. Indian J Pathol Microbiol. 2003;46:662-63.

Weekly epidemiological record. Geneva: World Health Organization. 2007;82(42):361-80.

Park K. Textbook of Preventive and Social Medicine. 21st ed. Jabalpur: Banarsidas Bhanot Publishers; 2011. Epidemiology of communicable disease. 244-50.

Azad K, Arora R, Gupta K, Sharma U. Lymphatic filariasis: Aspiration of adult gravid female worm from a soft tissue swelling. J Cytol. 2010;27(4):156-7.




How to Cite

Chavarkar, S. P. (2016). Lymphatic filariasis: the importance of screening all peripheral blood smears in low power for detection of asymptomatic cases. International Journal of Research in Medical Sciences, 5(1), 350–353.



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