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  Table of Contents  
Year : 2015  |  Volume : 33  |  Issue : 4  |  Page : 595-596

Human dirofilariasis: A fast emerging zoonosis in India

Department of Molecular Parasitology, National Institute of Malaria Research, Bengaluru, Karnataka, India

Date of Submission01-Jun-2015
Date of Acceptance08-Sep-2015
Date of Web Publication16-Oct-2015

Correspondence Address:
S K Ghosh
Department of Molecular Parasitology, National Institute of Malaria Research, Bengaluru, Karnataka
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Source of Support: None, Conflict of Interest: None

PMID: 26470975

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How to cite this article:
Ghosh S K. Human dirofilariasis: A fast emerging zoonosis in India. Indian J Med Microbiol 2015;33:595-6

How to cite this URL:
Ghosh S K. Human dirofilariasis: A fast emerging zoonosis in India. Indian J Med Microbiol [serial online] 2015 [cited 2020 Aug 8];33:595-6. Available from:

In recent years, several cases of human dirofilariasis inflicting different body parts including the present case report of oral dirofilariasis infected with Dirofilaria (Nochtiella) repens have been reported.[1] In the era of elimination of lymphatic filariasis (ELF) in human, recent reports on human dirofilariasis are fast emerging as a zoonotic disease in India.[2],[3]

Dirofilaria (Railliet and Henry, 1911) is a genus of the family Onchocercidae of the superfamily Filarioidea of the order Spirurida of the class Secernentea of the Subphylum Nematoda under the Phylum Nematozoa, which may form together with the Arthropoda, the Superphylum Ecdysozoa.[4] Domestic dogs, cats and wild animals are natural hosts of this nematode that accidentally infect human. Man is the dead-end host as the adult worms cannot produce microfilariae in human system. Different mosquito species are vectors that transmit the parasites.[5] Two species of human dirofilariasis, Dirofilaria immitis and D. repens, are most prevalent. These two species represent a zoonotic mosaic that have adapted to canine, feline and human hosts. They exhibit distinct developmental patterns with biological and clinical implications.[5],[6]

D. repens is the causative agent for subcutaneous dirofilariasis in Asia, and Sri Lanka is endemic for this zoonotic infection.[6]D. immitis is relatively less prevalent and has been reported in Malaysia.[3] In recent years, cases of human dirofilariasis are increasingly reported in India. Cases of D. repens are most commonly reported, followed by D. immtis; a few cases of Dirofilaria tenuis have also been reported.[2],[3] The transmission of the parasite depends mostly on local climate, and the recent trend of climate change favouring mosquitogenic conditions may face more challenging.[3]

In India, most of the cases have been reported from the States of Kerala, Coastal Karnataka and Maharashtra, whereas less number of cases has been reported from North India. Few cases have also been reported from Orissa and Assam.[3] Diagnosis of this disease is very difficult since there is limited expertise available on this subject. In many cases, identification of the parasite has been performed by the expert veterinarians. The diagnosis is performed based on the morphological features of the parasite, and DNA-based polymerase chain reaction method would be the best option.[3]

Anthelmintic chemotherapy is not routinely recommended. However, ivermectin and/or diethylcarbamazine have been used in few demanding cases. A symbiotic relationship between bacteria of the genus Wolbachia and various species of filariae, including D. immitis and D. repens, has provided a new option for the treatment of filariasis. Antibiotic treatment with doxycycline in oncocercosis resulted in complete block of embryogenesis of the filarial worms.[6]

It is evident from the current situation that human dirofilariasis is no more a rare zoonotic disease that has many endemic foci. In a sample survey, Khurana et al reported that 7% dogs were infected with microfilariae of D. repens.[1] Cats and dogs have also been found infected with D. immitis and D. repens in Orissa.[1] Treatment to infected animals and chemoprophylaxis with appropriate anthelmintic drugs are needed to check the zoonotic threat in human. It would not be out of context to say that in future animal species of Dirofilaria may become a species of human if adult worms start producing micorfilariae in human host. If this happens, we may have to recognise such animal, Dirofilaria, as another species of human filariasis. This hypothesis is exemplified with two recent reports. First, human filiarial worm Brugia malayi has been found in dogs in Kerala.[7] Second, Plasmodium knowlesi is a malaria parasite that is found in nature in long-tailed and pig-tailed macaques. Naturally acquired human infections were thought to be extremely rare until a large focus of human infections was reported in 2004 in Sarawak, Malaysian Borneo. Human infections have since been described throughout the Southeast Asia, and P. knowlesi is now recognised as the fifth species of Plasmodium causing malaria in humans.[8] Based on this similarity, 1-day Dirofilaria in human may cause a public health problem. Proper monitoring and awareness are the need of the day. A joint team, both from human and animal departments, needs to be constituted for routine surveillance of dirofilariasis in domestic animals to enumerate the endemicity and contains the enzootic transmission process. It would be important to implement the ongoing mass drug administration with diethylcarbamazine and albendazole under the ELF programme in all the endemic areas of the country. This might be an additional benefit to contain any unrelated cases of human dirofilarias, as observed among school children targeting intestinal helminths.[9]

 ~ References Top

Khurana S. Oral Dirofilariasis: A Case Report. Indian J Med Microbiol 2015;33.593-4.  Back to cited text no. 1
Bhat KG, Wilson G, Mallya S. Human dirofilariasis. Indian J Med Microbiol 2003;21:223.  Back to cited text no. 2
[PUBMED]  Medknow Journal  
Reddy MV. Human dirofilariasis: An emerging zoonosis. Trop Parasitol 2013;3:2-3.  Back to cited text no. 3
[PUBMED]  Medknow Journal  
Horst A. Dirofilaria and Dirofilarioses: Introductory Remarks. Proceedings of Helminthological Colloquium. Vienna; 2003.  Back to cited text no. 4
Pampiglione S, Canestri Trotti G, Rivasi F. Human dirofilariasis due to Dirofilaria (Nochtiella) repens: A review of world literature. Parassitologia 1995;37:149-93.  Back to cited text no. 5
Simón F, Siles-Lucas M, Morchón R, González-Miguel J, Mellado I, Carretón E, et al. Human and animal dirofilariasis: The emergence of a zoonotic mosaic. Clin Microbiol Rev 2012;25:507-44.  Back to cited text no. 6
Megat Abd Rani PA, Irwin PJ, Gatne M, Coleman GT, Traub RJ. Canine vector-borne diseases in India: A review of the literature and identification of existing knowledge gaps. Parasit Vectors 2010;3:28.  Back to cited text no. 7
Singh B, Daneshvar C. Human infections and detection of Plasmodium knowlesi. Clin Microbiol Rev 2013;26:165-84.  Back to cited text no. 8
Sunish IP, Rajendran R, Munirathinam A, Kalimuthu M, Kumar VA, Nagaraj J, et al. Impact on prevalence of intestinal helminth infection in school children administered with seven annual rounds of diethyl carbamazine (DEC) with albendazole. Indian J Med Res 2015;141:330-9.  Back to cited text no. 9
[PUBMED]  Medknow Journal  


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