🐱 FELINE ROTAVIRUS INFECTIONS 🦠
Understanding the Causes and Impact on Cats 🚫🤒
Feline rotaviruses are a type of
virus that belongs to the Reoviridae family, specifically classified as a genus
within this family. These viruses are widely distributed across the globe and
can be distinguished from other viruses when observed under negative-stain
electron microscopy (EM). They possess a distinct morphology, appearing as
70-nanometer-diameter intact virions that resemble a wheel, with a hub-like
core, spokes radiating outward as the inner layer of capsomeres, and a sharply
defined rim forming the outer layer.
Etiology and Epidemiology:
Rotaviruses are classified into
different serogroups (A through G) based on genetic and immunologic
similarities. They have been found in various animal species and are known to
be the primary enteric viral pathogens in humans, as well as in domestic
livestock, causing significant economic losses. However, while feline rotavirus
infection is common among cats, with up to 100% of populations showing
seropositivity, clinical disease is relatively rare.
Differentiation of rotavirus
strains of various origins can be achieved through the analysis of capsid
encoding genes (VP4, VP6, and VP7) using restriction endonuclease assay. Among
these genes, VP7 profiles are particularly efficient in distinguishing strains
of animal and human origin. Moreover, the nonstructural glycoprotein NSP4 of
group A rotaviruses from mice has been identified as a viral enterotoxin. The
amino acid sequences of this protein in rotaviruses isolated from diarrheal and
asymptomatic kittens were found to be similar. However, no consistent
differences were found between isolates from clinically healthy or ill cats.
Clinical Findings and Diagnosis:
Feline rotavirus infection was
first described in 1979 in kittens aged 6 weeks and 8 months who exhibited
semiformed to liquid stools. An experiment involving the transmission of the
virus isolated from the 6-week-old kitten to a 3-day-old, colostrum-deprived
kitten resulted in anorexia and diarrhea. Since then, feline rotavirus has been
more frequently identified in the stools of normal cats. Notably, a
transmission study using a strain isolated from a diarrheic cat failed to
induce disease in adult cats or kittens as young as 10 days.
The presence of rotavirus in
feces can be easily demonstrated using negative-stain EM or by performing
polyacrylamide gel electrophoresis and silver staining of directly extracted
RNA from feces. The latter method is more suitable for screening large numbers
of specimens. Additionally, a more sensitive PCR method has been developed for
the detection of feline rotavirus. Other methods, such as ELISA or latex
agglutination, have been used but are primarily designed for group A viruses,
while many feline isolates belong to other groups. Growing isolates in cell
culture can also be attempted, although this process is time-consuming.
Pathologic Findings:
Histologic findings associated
with feline rotavirus infection include swollen intestinal villi accompanied by
mild infiltration of macrophages and neutrophils. The viral antigen can be
detected through fluorescent antibodies, and virions can be visualized via EM
within epithelial cells.
Therapy, Prevention, and Public Health Considerations:
Symptomatic treatment is
recommended for diarrhea caused by feline rotavirus infection. The signs are
typically mild and transient, with no significant impairment of mucosal
integrity. Fluid therapy can be administered intravenously or subcutaneously,
depending on the severity of dehydration. Currently, no vaccine is available
for cats to prevent rotavirus infection.
Interesting Findings:
Genetic characterization of group
G3 canine rotavirus strains in Italy, the United States, and Japan, along with
human and simian rotavirus isolates, revealed highly conserved genetic
sequences in the VP4 and VP7 genes, indicating close genetic homogeneity.
Rotaviruses from different hosts can infect other species experimentally, but
such cross infections are generally asymptomatic. Notably, there is evidence
from molecular studies suggesting that feline rotaviruses or recombinant
strains involving feline rotaviruses might have infected humans in Japan,
Hungary, and Italy. Similar evidence was found in Thailand, where a human
isolate from an infected infant with diarrhea displayed close genetic and phenotypic
similarities to other human and feline strains.
Feline rotavirus infection is
relatively uncommon compared to its prevalence in other animals, and clinical
disease resulting from this infection is rare in cats. Diagnosing feline rotavirus
can be achieved through various laboratory methods, with PCR being the most
sensitive technique. While treatment is symptomatic and no specific vaccine is
available for cats, ongoing research into the genetic relationships and
transmission of rotaviruses among different species provides valuable insights
into the understanding and management of these viral infections.
NOROVIRUS INFECTION 🦠
Discovering a Novel Enteric Norovirus in Lions 🦁
A novel enteric norovirus,
belonging to the calicivirus family and related to human noroviruses, was
isolated from a lion cub (P. leo) that had succumbed to hemorrhagic enteritis.
This virus was differentiated from feline calicivirus (FCV) using molecular methods
and showed the closest genetic relationship to human noroviruses. Although
noroviruses typically exhibit species adaptation, they can infect other species
with mild or unapparent symptoms. Further research is necessary to determine
the clinical significance of this virus in lions.
TOROVIRUS-LIKE AGENT INFECTION 🦠
Exploring a Mysterious Virus in Cats 😺
During a microbiological survey
of cats displaying the syndrome of protruding nictitating membranes and
diarrhea, a novel virus capable of hemagglutinating rat erythrocytes was
detected. However, conclusive evidence linking this virus to the observed
syndrome remains lacking, as it was only isolated from a small proportion of
affected cats and even from some unaffected cats. While tests such as
hemagglutination inhibition (HI) and immune electron microscopy (EM) suggested
that the virus was torovirus-like, confirmatory findings through PCR and
thin-section EM were inconclusive. Attempts to grow the virus in cultured cells
were unsuccessful. Experimental inoculation of specific-pathogen-free (SPF)
kittens resulted in mild, intermittent diarrhea and pyrexia accompanied by
hematologic changes. While most cats have antibodies against this agent, its
significance as an enteric pathogen remains unclear. Additionally, in another
study, torovirus particles were not detected in the feces of cats with
protruding nictitating membranes.
FELINE REOVIRUS INFECTION 🦠
Uncovering the Role of Reoviruses in Cats 🐈
All mammalian reoviruses are
categorized into three serotypes, and all three have been isolated from cats.
Feline reoviruses have generally been considered minor respiratory or ocular
pathogens, although they can be isolated from both the respiratory and enteric
tracts. Experimental inoculation of kittens with serotype-2 isolates has led to
the development of mild diarrhea. Serological surveys indicate the widespread
presence of feline reoviruses in nature.
OTHER ENTERIC VIRAL INFECTIONS 🦠
Exploring Viral Infections with Unclear Pathogenic Role 🧪
Numerous other viruses have been
detected in the stools of both normal and diarrheic cats, but their
significance as pathogens remains uncertain. These viruses include
parvovirus-like particles (unrelated to feline panleukopenia virus),
picornavirus-like particles, coronavirus-like particles (morphologically
distinct from feline infectious peritonitis viruses and feline enteric
coronaviruses), "togavirus-like particles," and "thornapple-like
particles."
In conclusion, feline rotavirus
infection is relatively uncommon in cats, and clinical disease is rare.
Diagnosis of feline rotavirus can be achieved through various laboratory
methods, with PCR being the most sensitive. Treatment is symptomatic, and no
specific vaccine is available for cats. Additionally, novel viruses such as
norovirus and torovirus-like agents have been discovered, highlighting the need
for further research to understand their clinical significance. Feline reovirus
infection has also been identified, and the role of other enteric viruses in
feline health requires further investigation.
Understanding the role of these
other enteric viruses in feline health is an ongoing area of research. While
they have been detected in the stools of cats, their actual pathogenicity and
clinical significance are not yet fully understood. Parvovirus-like particles,
picornavirus-like particles, and coronavirus-like particles have been
identified, but their relationship to specific diseases or health conditions in
cats remains unclear. Thorough investigation and studies are necessary to
determine their potential impact on feline well-being.
Researchers have also come across
"togavirus-like particles" and "thornapple-like particles"
in cats, but their role in feline health and disease is still a subject of
investigation. More studies are needed to determine their characteristics,
transmission patterns, and any associated clinical manifestations.
In summary, while feline
rotavirus infections are relatively rare in terms of causing clinical disease,
they still play a significant role in veterinary medicine. The diagnosis of
feline rotavirus can be achieved through various laboratory methods, allowing
for appropriate management and treatment. Additionally, ongoing research into
other enteric viruses in cats, such as noroviruses, torovirus-like agents, and
reoviruses, aims to shed light on their impact on feline health.
As our understanding of these
viruses grows, it will enable us to develop more effective diagnostic tools,
prevention strategies, and potential vaccines to protect the feline population.
Further studies are required to uncover the exact role of these viruses and
their potential implications for both feline and human health.
By staying informed about
emerging viral infections and actively supporting research efforts, we can
continue to promote the health and well-being of our beloved feline companions.
Regular veterinary check-ups, responsible hygiene practices, and proper
sanitation measures are crucial in minimizing the risk of viral infections and
ensuring the overall health of our feline friends.
