Prevalence of cystoisosporosis among cats in Chennai

Introduction

Cystoisospora spp., particularly C. felis and C. rivolta, are common coccidian parasites affecting the intestinal tract of domestic and stray cats worldwide. Infection occurs through ingestion of sporulated oocysts from contaminated environments or paratenic hosts such as rodents and lizards (Dubey & Greene, 2012) [1] . Kittens and stressed animals are more susceptible, often showing diarrhoea, dehydration and poor growth, whereas adults may remain asymptomatic carriers (Lappin, 2010) [2] . Warm and humid climates favour oocyst sporulation, leading to higher environmental contamination and transmission (Dubey, 2018) [3] . Although intestinal parasites in cats are reported from several parts of India, limited information is available from Tamil Nadu, especially Chennai. Increasing urban stray cat populations and close human-animal contact highlight the need for surveillance. Hence, the present study was conducted to investigate the prevalence of Cystoisospora spp. in cats in Chennai and to assess the influence of age, sex, breed, living conditions and seasonal factors.

Materials and Methods

Study period and study area

In the present investigation, 200 faecal samples of domestic and stray cats were collected randomly from various parts of Chennai. Sampling considered different factors such as category (pet/stray), age, gender, breed, and season. The study was conducted from December 2024 to October 2025.

Faecal examination: Fresh faeces were collected and examined within a few hours or stored under refrigeration to prevent sporulation and degradation (Lappin, 2010) [2] .

A measured amount of faeces is emulsified in flotation solution using sheather's sugar solution. The suspension is strained to remove large particles and filled into a flotation chamber or topped to form a meniscus before placing a coverslip (Zajac & Conboy, 2012) [4] . After 10-15 minutes, the coverslip is transferred to a slide and observed microscopically at 10× and 40× magnification (Dubey, 2018) [3] . Cystoisospora felis and C. rivolta oocysts are identified based on size, double-layered wall, and internal sporocyst development in sporulated stages (Dubey & Greene, 2012) [1] . C. felis oocysts are larger, usually spherical to subspherical, measuring approximately 38-51 × 27-39 μm (Dubey, 2018) [3] . C. rivolta oocysts are smaller and typically ellipsoidal, measuring 18-29 × 16-23 μm (Soulsby, 1982) [5] .

Data analysis

Numerical data collected were analysed using IBM-SPSS software version 24.0.

Results and Discussion

Out of 200 cats examined, 19 were positive for Cystoisospora spp., giving an overall prevalence of 9.5% (Fig. 1). All positive samples were subjected to micrometry for specieslevel confirmation (Soulsby, 1982) [5] (Fig. 2). Contrary to the present findings, Borkataki et al. (2013) [6] reported a much higher prevalence (80%) among stray cats in India. In Bengaluru, however, a lower prevalence of 3.47% was reported in cats from mixed populations including stray, owned, and shelter cats (Gautham et al., 2018) [7] .

among cats in Chennai

Age-wise prevalence: Age groups were classified as <1 year, 1-3 years, and >3 years. Prevalence was highest in kittens (<1 year) at 13.51%, followed by 7.41% in 1-3 years and 6.94% in >3 years (Table 1). Although the association between age and infection was not statistically significant, kittens showed higher infection rates. Lappin (2010) [2] stated that young animals are more likely to shed oocysts. Stress factors such as weaning, crowding, and poor hygiene also predispose kittens to infection. A similar trend was reported by Neeraja et al. (2023) [8] , who found 36.76% prevalence in cats below six months of age.

Pet vs stray cats

Of 110 pet cats, 6 (5.45%) were positive, compared to 13 of 90 stray cats (14.44%). A statistically significant association (P<0.05) was observed between living status and prevalence (Table 2). Higher infection among stray cats agrees with Dubey (2018) [3] , attributing increased exposure to predation, scavenging, inter-cat interactions, and limited veterinary care. Statistically significant at 5% level Gender-wise and breed-wise prevalence Among 94 male cats, 11 (11.70%) were positive, while 8 of 106 females (7.55%) were infected. There was no significant association (P>0.05) between sex and prevalence (Table 3). For breed, 95 domestic shorthair cats, 85 purebred cats, and 20 others were assessed. Prevalence was 11.58%, 7.06%, and 10% respectively, with no significant association (P>0.05) (Table 4).

Seasonal occurrence

Prevalence was highest in summer (12.86%), followed by monsoon (10.91%) and winter (5.33%) (Table 5). Although no statistically significant association was observed, higher summer prevalence may be due to increased oocyst sporulation under warm and humid conditions.

Acknowledgement

AcknowledgementsThe authors are thankful to the Department of Veterinary Parasitology, Madras Veterinary College, Chennai, for providing laboratory facilities and technical assistance during sample collection and microscopic examination. The cooperation of pet owners, veterinary hospitals, and animal welfare organizations in Chennai is gratefully acknowledged.

References

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