Therapeutic management of pseudomalaria in a flock of pigeons with chloroquine

Abstract

Two Indian rock pigeons aged 2–3 months presented to the Referral Veterinary Polyclinic and Teaching Veterinary Clinical Complex, Indian Veterinary Research Institute, Utter Pradesh with a history of decreased feed intake, twisting of the neck, and inability to fly. The same symptoms also caused the deaths of two other birds from the same flock. The bird seemed dull and depressed during a clinical examination, had ruffled feathers, a tilted head and circling. Examination of a faecal sample showed no intestinal parasites. Upon observation of a blood smear, many intracytoplasmic characteristic halter-shaped Hemoproteus columbae gametocytes could be detected. The case was diagnosed as pigeon pseudomalaria. The treatment was initiated with chloroquine@10 mg/kg body weight in drinking water for 5 days along with the multivitamin supplementation for one week. Permethrin spray was applied externally to the whole flock in the house to get rid of the fly vector. The clinical state of the birds was evaluated one week after initiation of the therapy. The pigeon had an uneventful recovery and the blood smear examination revealed no haemoparasites.

Introduction

Pigeons are one of the most attractive birds, and over thousands of years, people have kept them as pets and revered them as cultural and religious symbols. Nonetheless, pigeons encounter a range of health issues, with parasitic infections being the most prevalent. These infections can significantly compromise their immune systems, egg production, growth rate, weight gain, and can even lead to fatal outcomes (Palinauskas et al. 2009; Cellier-Holzem et al. 2010; Joshi et al. 2017). In rock doves, including domestic pigeons Haemoproteus columbae (H. columbae) is the representative cause of the haemosporidian infection worldwide (Rosyadi et al. 2021). In tropical regions, pigeons are frequently afflicted by the haemoprotozoan H. columbae (Bennett and Peirce 1990; Joshi et al. 2017). The vector of the disease is haematophagous fly known as Pseudolynchia canariensis, a hippoboscid fly. (Bennett et al. 1993; Valkiunas 1997). The diagnosis of Hemoproteus infection often involves the identification of intraerythrocytic gametocytes in thin blood smears when examined under a microscope. The illness induced by H. columbae in pigeons is occasionally termed “pseudomalaria” or “pigeon malaria” due to the parasite's resemblance to a type of Plasmodium species (Friend and Franson 1999). Although it typically doesn't cause any harm to adult birds, H. columbae can trigger a deadly illness in young, stressed pigeons. Clinical signs of this infection may include circular movements, lethargy, loss of appetite, depression, difficulty breathing, and diarrhoea (Varshney et al. 2014; Maharana and Kumar 2017; Joshi et al. 2017). There have been relatively few studies conducted on hemoprotozoans, even though the existence and impact of helminth parasites in pigeons are well-documented. H. columbae infections are commonly observed in pigeons in several Indian states, including Kerala, Uttar Pradesh, Mumbai, and Gujarat (Ravindran et al. 1999; Raval et al. 2016; Shinde et al. 2008; Jahan et al. 2011; Maharana and Kumar 2017). However, evidence on the incidence of pseudomalaria in Indian subcontinent is lacking. This study deals with the diagnosis and management of a severe H. columbae infection in a flock of domestic pigeons.

Case description

Case history and clinical observation

From a flock of 35 pigeons, two pigeons were presented as a representative to the ICAR-Indian Veterinary Research Institute's Referral Veterinary Polyclinic in Izatnagar with a history of decreased feed intake, lethargy, circling motions, torticollis, weakness, and inability to fly. Two pigeons from the same group died earlier exhibiting identical clinical symptoms. However other pigeons of the flock were having variable degree of morbidities with related symptoms as of the presented pigeons. The whole flock of pigeons had received the recommended Ranikhet disease vaccinations. During clinical examination, the subjects were found to be depressed, having continuous circling movement with torticollis (Fig. 1). However, the PLR reflex was intact in both eyes. Rectal temperature was 105°F and breathing movements indicate mild dyspnoea. There were no ectoparasites found over body of animal.

Fig. 1.

Pigeons manifesting torticollis

Laboratory investigation and diagnosis

There were no intestinal parasites found in the faecal sample examination. Blood was drawn from the peripheral wing vein using a vein puncture, placed in vials containing potassium EDTA for routine haematology and thin blood smears were prepared for blood smear examination. The thin blood smears were stained using the Giemsa technique in line with the standard approach (Soulsby 1982), and viewed in an oil immersion lens (Lawrence & Mayo, binocular microscope) to identify hemoprotozoan parasites. Haemoprotozoa parasite was identified by the presence of halter- or crescent-shaped, light-blue gamonts located partly intraerythrocytic around the host cell's nucleus (Soulsby 1982) (Fig. 2). The typical morphology of gamonts confirms the parasite as H. columbae. Based on clinical signs and morphology of parasites in blood smear the case was diagnosed as pseudomalaria or pigeon malaria.

Fig. 2.

Peripheral blood smear revealing halter shaped gamonts of Haemoproteus columbae

Haematological parameters revealed low haemoglobin, packed cell volume and red blood cell count, whereas total leucocyte count, heterophils, lymphocytes, eosinophils, and basophils percent were within normal limits (Table 1).

Table 1.

Haematological parameters of pigeons

Parameters	Pigeon 1	Pigeon 2	References*
Hb (g/dl)	7.5	7.9	7.76–16.0
PCV (%)	28	30	32–55
TEC (106/mm3)	1.35	1.65	2.12–3.95
TLC (× 103/mm3)	12.8	17.3	12.5–35.5
Heterophils	47	48	18–50
Lymphocyte	38	40	32–58
Monocyte	12	8	5–19
Eosinophils	3	4	4–17
Basophils	0	0	0–5

*Ihedioha et al. (2016)

Therapeutic intervention

The treatment for whole flock was initiated with Chloroquine at dose rate of 10 mg/kg body weight in drinking water (Karamba and Mukhtar 2012) for 5 days. Multivitamins (Vitamin-B complex, Vitamin E, Vitamin D₃ and Vitamin A) were supplemented @0.2 ml/bird for 7 days, due to their ability to reduce stress and boost immunity. To manage flies, the owner was instructed to regularly clean the litter and spray the pigeon home with Permethrin (0.25% spray) (Permin and Hansen 1995). A follow-up blood smear after 7 days of testing confirmed that the pigeons had fully recovered. After one week of regular assessment and monitoring, no obvious clinical signs are evident (Fig. 3).

Fig. 3.

Healthy pigeons after one week of chloroquine treatment

Discussion

While many cases of H. columbae infections in pigeons go unnoticed and pose no significant health threats, young pigeons and those with weakened immune systems can experience typical neurological and humoral disease symptoms when infected. Treatment is only given when a flock is fatally infected, and the parasitaemia rate is usually high (Nematollahi et al. 2012; Raval et al. 2016; Joshi et al. 2017). A deficiency of pantothenic acid may be the reason for the clinical symptoms seen in the birds, which most likely resulted from host and malarial parasite competition for pantothenic acid (Margret and Petrak 1969). Recent studies have shown that H. columbae induces significant necrosis and the development of exo-erythrocytic megalomeronts in muscle, heart, liver, and lungs, which can result in a fatal infection. After severe infections meront block the capillaries and build up in the lungs of birds. As a result, symptoms like pneumonia appear, which could result in the bird's death (Marques et al. 2007). The destruction of parasitized erythrocytes may be hypothesized as the cause of the decline in haemoglobin, packed cell volume and red blood cell count. The uneventful recovery of pigeons receiving Chloroquine medication for 5 days, proves chloroquine to be a potential candidate for management of pigeon malaria. The anti-malarial drug chloroquine is a 4-amino-quinoline which hampers action of heme polymerase due to which toxic heme component build in parasite leading to death of the parasite. Researchers from different countries have documented cases of H. columbae infection in pigeons, often exhibiting similar clinical symptoms with varying approaches to treatment and management (Murata 2002; Marques et al. 2007; Varshney et al. 2014; Chand et al. 2018).

To sum up the findings from the present study, H. columbae is a common blood parasite in pigeons, leading to illness and mortality, particularly in young pigeons with weakened immune systems or those experiencing stress. Management of the disease can be effectively done by Chloroquine however more exhaustive studies need to be conducted for validating the drug as a drug of choice for haemoproteus infection. The disease must always be considered in differential diagnosis of neurological diseases. Early identification of the disease can save the valuable animals of interest.

Authors’ contributions

This is an uncommon clinical case of H. columbae infection in a pigeon, being reported by VKS. UKD guided to build the manuscript. DPP helped in microscopic examination of H. columbae. HS, SM, PS and SKP helped in correction of manuscript.

Declarations

Conflict of interest

None of the authors have any financial or personal affiliations with individuals or organizations that might unduly influence or prejudice the content of the paper.