Preliminary Investigations on Occurrence of Haemoproteus spp. in Pigeons (Columba livia)

Introduction

India is blessed with a wide range of mammals, reptiles and avian species. The domestication of such species has been practiced from a long period of time where animals such as cattle, buffalo, sheep, goat etc. are kept for milk and draft purposes; dogs and cats as pets/companions; birds such as pigeons, budgerigars, cockatiels etc. are kept as pets [1] . Out of all birds, pigeons have been kept by many bird enthusiasts as pets. A wide variety of pigeons are available in pet markets which include some exotic varieties. On the other hand, there is a remarkable population of indigenous free-living pigeons which are often found in urban and rural areas [1] . Such pigeons often seek shelter in human localities because of drastic changes in natural habitats, deforestation and expansion of infrastructure. Moreover, factors such as vector population, climate change etc. also affects disease epidemiology and progression. Sick birds, due to their presence in human localities, are often seen by affectionate people who take them to nearby hospital for treatment while its close proximity to humans also renders them vulnerable to human-associated conflicts (e.g., kite string injuries, attacks by stray dogs, accidental injuries, damage by household hazards etc.). Therefore, pigeon is one of the most commonly reported birds with wide range of infectious and noninfectious conditions at veterinary hospitals [1] . This necessitates initiation of target-specific disease investigations. Various infectious diseases such as pigeon pox, coccidiosis, endoparasitic infestations, ectoparasitic infestations, kite string injuries, paramyxovirus-1 infection, pseudomalaria etc. have been documented in pigeons [1,2,3,4,5] . Out of all, pseudomalaria is a common vectorborne disease which is caused by Haemoproteus spp. infecting the blood of pigeons and other Columbiformes birds. Pigeon fly, viz., Pseudolynchia canariensis, has been described to play important role in transmission of this pathogen [5,6] . So far, Haemoproteus spp. infection has not been studied thoroughly in hospital population of pigeons. Hence, an attempt was made to screen Haemoproteus spp. infection in 59 Columbiformes birds. The details of the study have been elaborated in the present paper. Moreover, this could have been also due to variations in strains of NDV viruses; however, there was no evident outbreak (e.g., more number of birds with similar signs and symptoms at a time) during the period of study. Generally, Haemoproteus spp. infection is termed as pseudomalaria or pigeon malaria which is transmitted by pigeon fly (Pseudolynchia canariensis). Role of slender pigeon louse (Columbicola columbae) is also suspected for transmission of the disease. Upon infection, this agent is observed to infect red blood cells of the pigeons forming a horse-shoe shaped structure around the nucleus. The protozoa can affect both, young and adult pigeons where stress factors (e.g., parasitic infestation, nutritional deficiencies, environmental stress etc.) contribute to development of clinical symptoms. The affected pigeons are often found to have weakness, dullness, ophthalmic discharge, abnormal neck deviation, reduced appetite, abnormal droppings, difficulty to fly, circling movements in some cases, inability to protect against predators and death in severe cases. The diagnosis of Haemoproteus spp. is comparatively easy in field condition and is often made by blood smear examination.

Materials & Methods

Here, blood samples can be directly collected from wing veins of the bird while impression smears can be prepared from ongoing hemorrhages in case of injuries to screen the birds.

Advanced diagnostic tests such as Polymerase Chain Reaction (PCR) has been used for molecular confirmation of species. Drugs such as chloroquine, primaquine and buparvaquone have been described for use as suitable treatment options with variable clinical outcome [5,6,7] . Diamond doves are smaller in size as compared to pigeons and are mostly kept as pets.

Conclusion

The overall presence of Haemoproteus spp. was observed to be 35.19% among screened population of pigeons (n=54) where subclinical infection was higher (27.78%) as compared to clinical infection (07.41%). This baseline data indicates that presence of Haemoproteus spp. should be periodically checked in pigeons to ascertain current status of infection, disease progression and epidemiology in larger population.

Conflict of Interest & Ethical Approval

Authors declare no conflicts of interest with regards to funding.

Acknowledgement

AcknowledgementsAuthors acknowledge support from Principal; HoD of VCC and other departments; PG residents and supporting staff of VCC and other departments of College of Veterinary Science & Animal Husbandry, KU, Himmatnagar; authorities of KU, Gandhinagar for provision of necessary working facilities and support.

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