Transmission of Cytauxzoon Felis by Amblyomma Americanum: Engorgement Weight of Nymphs and Attachment Time of Adults for Transmission to Domestic Cats

Cytauxzoon felis causes the most severe tick-borne disease of domestic cats in the United States. The geographic distribution and prevalence of cytauxzoonosis seem to be increasing as the range of Amblyomma americanum expands. However, disease prevalence and life cycle have not been completely understood, and diagnosis and treatment remain challenging. My research focused on determining the prevalence of C. felis, a better understanding of life cycle, and developing supportive diagnostic techniques.To contribute establishing the prevalence of C. felis in domestic cats, blood was collected from 380 free-roaming cats in 2014 in Oklahoma and 292 in 2012�2014 in Iowa. PCR detected C. felis DNA in 3 of 380 (0.8%; 0.22�2.3%) feline samples from OK and 0 of 292 (0.0%; 0.0�1.3%) from IA. Prevalence of C. felis infection was examined in C. felis-exposed A. americanum using staining technique and PCR. Cytauxzoon felis-infected salivary glands were not observed in 350 fed ticks (0.0%; 0.0�1.0%), whereas 54 of 352 (15.3%; 11.7�19.5%) salivary glands from flat ticks were infected with C. felis. PCR detected C. felis DNA in 4 of 358 (1.1%; 0.30�2.84%) ticks. Transmission of C. felis from A. americanum to a domestic cat was demonstrated in <72 hours. Tick morphometric method was examined as a supportive diagnostic technique and shown to be less practical to predict probability of transmission. Additionally, nymphal sexual dimorphism was examined with A. americanum, A. maculatum, Dermacentor andersoni, D. variabilis, and Rhipicephalus sanguineus. The mean body weight of engorged nymphs that became females was significantly greater than that of nymphs that molted to males in A. americanum (t=32.3; P<0.0001), A. maculatum (t=-9.70; P<0.0001), D. variabilis (t=15.7; P<0.0001), and R. sanguineus (t=5.17; P<0.0001), whereas, the mean body weight of D. andersoni engorged nymphs that became males was significantly greater (t=8.71; P<0.0001) than that of nymphs that molted to females. Overall, these studies have contributed to a better understanding of the prevalence of C. felis and life cycle with timing of transmission. Additionally, the findings in nymphal sexual dimorphism may help explain potential differences in prevalence of tick-borne pathogens between female and male ticks.Veterinary Biomedical Science

Prevalence of infection in healthy free-roaming cats in north-central Oklahoma and central Iowa

Case summary Cytauxzoonosis is a tick-borne disease of cats, and Oklahoma (OK), USA, is considered an enzootic state. To determine the prevalence of Cytauxzoon felis , blood was collected from free-roaming cats, as they are frequently exposed to tick vectors. Our objective was to determine the prevalence of C felis infection in free-roaming cats in north-central Oklahoma and central Iowa (IA). Infection with C felis was determined using DNA extracted from blood and PCR amplification. Blood was collected from 380 free-roaming cats between January and April in 2014 in OK. DNA from C felis was detected in 3/380 (0.8%; 95% confidential interval [CI] 0.22–2.3%). In IA, 292 blood samples were collected between 2012 and 2014. No C felis -infected cats were detected (0; 95% CI 0–0%). Relevance and novel information The prevalence of C felis (0.8%) in north-central OK reported herein was lower than the previously reported 3.4% in domestic cats in OK. Our study supports that the prevalence in a given enzootic area can vary by location and from the pool of cats sampled. None of 291 (0%) cats were infected with C felis in central IA. To date, only one case of cytauxzoonosis in a domestic cat has been reported in IA. It is important to monitor cats for C felis infections in northern US states, as geographic distribution of Amblyomma americanum expands northward. As free-roaming cats have more contact with the tick vectors of C felis , this population allows us to monitor the expansion of C felis distribution

Sequential changes in pathophysiology of systemic inflammatory response in a disseminated neonatal herpes simplex virus (HSV) infection

AuthorBACKGROUND: Disseminated neonatal herpes simplex virus (HSV) infection causes a typical systemic inflammatory response syndrome and has a high mortality rate. However, the validity of anti-inflammatory intervention against this condition remains unknown. OBJECTIVES: We sought to demonstrate the sequential changes in the pathophysiology of disseminated neonatal HSV infections. STUDY DESIGN: The HSV serum copy number as well as high-mobility group box 1 (HMGB1) and cytochrome c concentrations, which predict the severity and mortality rate of sepsis, were sequentially evaluated in a patient with disseminated neonatal HSV infection caused by HSV-2. RESULTS: As the patient presented with evidence of hyper-inflammation and severe illness, we empirically undertook anti-inflammatory intervention that included the administration of prednisolone, high-dose immunoglobulin, and blood exchange therapy in addition to high-dose acyclovir (ACV) therapy. The patient survived without significant neurological sequela. We found that (1) the serum concentrations of both HMGB1 and cytochrome c were extremely high, (2) temporal increases in these biomarkers were observed after admission, and (3) interestingly, the increase in HMGB1 level preceded that of cytochrome c. These results suggested that the pathophysiology of this condition changed sequentially in a dramatic manner, and the timing of our anti-inflammatory intervention was prior to the transition of pathological status from hyper-inflammation to massive apoptosis. CONCLUSIONS: Anti-inflammatory intervention may only be effective if it is undertaken during the early phase of disseminated neonatal HSV infections