Veterinary Public Health and Epidemiology- ICAR JRF/SRF 2024

• Epidemiology of Relative Risk (RR):
• Definition: Relative risk (risk ratio) measures the strength of association between an exposure and a disease outcome in prospective/cohort studies [Statement A is TRUE].
• Formula: Calculated as the incidence in the exposed ($I_e$) divided by incidence in the unexposed ($I_u$):

Statement B erroneously states it divides unexposed risk by exposed risk [Statement B is FALSE].

• Interpretation: $\text{RR} \gt 1$ signifies increased risk among exposed individuals compared to unexposed [Statement C is TRUE].
• Case-Control Inapplicability: Because case-control studies select subjects based on disease status rather than population denominators, true incidence cannot be computed, making RR uncalculable directly (the Odds Ratio, OR, is used as an estimate) [Statement D is TRUE].

Correct option: (2) (A), (C) and (D) only.

• Diagnostic Test Accuracy Metrics:
• Negative Predictive Value (NPV) is defined as the mathematical probability that an animal testing negative in a diagnostic assay is truly free of the disease:

• Definitions of Other Parameters:
• Diagnostic Sensitivity (DSe): Probability that a diseased animal tests positive ($\frac{TP}{TP+FN}$).
• Diagnostic Specificity (DSp): Probability that a healthy animal tests negative ($\frac{TN}{TN+FP}$).
• Positive Predictive Value (PPV): Probability that an animal testing positive truly has the disease ($\frac{TP}{TP+FP}$).

Correct option: (4) Negative Predictive Value

• Foundational History of OIE: The Office International des Epizooties (OIE)—now known as the World Organisation for Animal Health (WOAH)—was established on January 25, 1924 in Paris, France.
• Historical Catalyst: The impetus was an international catastrophe caused by Rinderpest (cattle plague). In 1920, a shipment of zebu cattle from India transiting through the port of Antwerp (Belgium) en route to Brazil introduced rinderpest into Western Europe, devastating livestock herds and prompting 28 nations to unite to create an international veterinary surveillance agency.

Correct option: (2) Rinderpest