# High Prevalence of Multi-Viral Co-Infections and Low Rabies Seropositivity in Stray Cats of Shenzhen, China

## TL;DR

Stray cats in Shenzhen commonly carry multiple viruses and have low rabies protection, posing a public health risk.

## Contribution

This study reveals high rates of multi-viral co-infections and low rabies immunity in Shenzhen's stray cat population.

## Key findings

- Most stray cats were infected with at least one virus, with frequent co-infections.
- Rabies virus was not detected, but only 6% of cats had rabies antibodies.
- FCV and FPV co-occurred most frequently, suggesting non-random co-infections.

## Abstract

Stray cats (Felis vaga) can carry and spread diseases that affect both other cats and sometimes people. In this study, we wanted to find out how common certain important viruses are among stray cats in Shenzhen, China. We also checked if the cats had protection against rabies, a serious disease that can be passed to humans. We collected samples from 126 stray cats between June and August 2024. Our tests showed that these viruses were very common overall. Most cats were infected with at least one virus, and many were infected with more than one at the same time. We did not find the rabies virus in any cat. However, very few cats had antibodies against rabies, meaning they were not protected from the disease and could potentially spread it if infected. This study tells us that stray cats in Shenzhen commonly carry several cat viruses and have low immunity to rabies. This information is important for planning strategies to manage the stray cat population and to protect both cat and human health.

Stray cats (Felis vaga) are key hosts for feline and zoonotic pathogens. From June to August 2024, we conducted a cross-sectional study across six districts in Shenzhen, China, involving 126 cats sampled from three types of sites. Multiple specimens were tested via quantitative real-time PCR (qPCR) for feline coronavirus type I (FCoV-I), feline calicivirus (FCV), feline herpesvirus type I (FHV-I), feline panleukopenia virus (FPV), and rabies virus (RABV); serum was analyzed for RABV-neutralizing antibodies by the fluorescent antibody virus neutralization (FAVN) assay. The overall pathogen positivity was 89.68%. FPV was most prevalent (61.90%), followed by FCV (57.14%), FCoV-I (46.83%), and FHV-I (23.02%). No RABV nucleic acid was detected. The co-infection rate reached 62.70%, primarily dual infections (33.33%). Geographical variation was observed, with significantly higher FCoV-I in Longgang than Futian (p < 0.05). RABV seropositivity was only 6.00%. FCV and FPV co-occurred most frequently (Jaccard = 0.456). All pathogen pairs had relative risk (RR) > 1, suggesting non-random co-infections, though not significant after correction. In summary, major feline pathogens are widespread with frequent co-infections among Shenzhen stray cats, while low rabies immunity indicates potential public health risk. Targeted control measures are warranted.