ABSTRACT
Hantavirus is an emerging zoonotic virus, cause of fatal diseases in humans. Brown rats (Rattus norvegicus) are known reservoir host for Seoul hantavirus. This is the second report of prevalence of antibodies against hantavirus in brown rats in Grenada. Sera from 169 brown rats were tested using ELISA for antibodies against hantavirus. Prevalence of antibodies was found in 47 rats (27.5%). There was no significant difference related to age and sex of seropositive rats. Although no case of hantavirus infection in humanshas been recorded in Grenada, the presence of moderate infection in reservoir host should be considered a risk factor for disease transmissi on in humans.
ABSTRACT
Aim: Brown rats (R. norvegicus), a natural intermediate host for Cysticercus fasciolaris, are widely distributed in Grenada. C. fasciolaris causes cysts in a number of organs, but with greater frequency in the liver. The purpose of this study was to investigate the alterations of serum chemistry particularly serum proteins and activity of liver enzymes associated with liver cysts in brown rats infected with C. fasciolaris, as well as to assess their performance in the diagnosis of Cysticercus fasciolaris. Study Design: In this cross sectional study, 170 brown rats were anesthetized and blood was obtained directly from the heart and collected in red-top tubes. The rats were then euthanized, and dichotomously classified as positive or negative for Cysticercus fasciolaris based on the presence or absence of Cysticercus fasciolaris-associated cysts, grossly and/or histopathologically. Methodology: For both groups of rats (positive or negative), the concentrations of each specific protein (g/dL), selected liver and pancreatic enzymes (U/L), metabolic waste products (mg/dL) and electrolytes (mg/dL) were measured using Vet Test (IDEXX, USA). Cut-off points for test values of liver enzymes were set at 2-fold or greater than upper reference limit. For all other analytes, test values that were outside the reference interval were considered to be diagnostically relevant. In order to determine the diagnostic performance and agreement between liver enzymes and Cysticercus fasciolaris-associated liver cysts, predictive values and Cohen’s kappa statistics, respectively were calculated. Results: The activity of AST significant increased among the infected brown rat population. The sensitivity and specificity of AST in detecting Cysticercus fasciolaris in brown rats was 76% and 59%, respectively. The positive and negative predictive values of AST were (80%) and (35%) respectively. Based on Cohen’s kappa, AST showed good agreement to gross/histopathology [0.4, 95% CI 0.16 – 0.53, SEkappa 0.42] in the detection of Cysticercus fasciolaris-associated liver cysts. Conclusion: AST is the most reliable enzyme in detecting Cysticercus fasciolaris in brown rats, and thus C. fasciolaris should be included among the differential diagnoses whenever increased serum activity of AST are observed in brown rats.
ABSTRACT
The aim of the study was to determine the serum antibodies and coproantigens for Cryptosporidium spp. in brown rats from Grenada. Intestinal contents from 99 and serum from 169 brown rats (Rattus norvegicus) during May to July 2017 were examined for coproantigens and antibodies for Cryptosporidium spp. respectively. Giardia/Cryptosporidium Quick Chek (Tech Lab Inc, USA) was used to detect Cryptosporidium coproantigens in intestinal contents. Prevalence of antigens was 2.02%, signifying active infection. Serum anti-Cryptosporidium antibodies against Cryptosporidium were tested using commercial “qualitative rat Cryptosporidium antibody (Anti-CRY) ELISA kit (My BioSource, Santiago, CA, USA). Serum antibodies were present in 29.5% of the rats indicating a heavy exposure of Cryptosporidium in brown rats from Grenada. The prevalence rate of antibodies in younger rats (up to100g weight) 42.1%, was statistically significant compared to adults (> 100 g) 28.0%. Infected rats in nearby human dwellings may prove a potential Cryptosporidium source of infection to man and animals. This is the first report of Cryptosporidium infection in brown rats in Grenada, West Indies.