Objective:To do the systematic comparison of prevalence of anaplasmosis byPCR andGiemsa stained thin blood smear (GSTBS) based parasitological assays in dairy cattle ofPunjab, which has not been reported yet.To analyse the haematobiochemical alterations in infected animals to arrive at the conclusion regarding the pathogenicity induced byAnaplasma marginale (A. marginale) in latent and patent infection.Methods:Study was conducted on320 animals (236 cows,62 calves and22 buffaloes) ofPunjab,India.PCR on genome ofA. marginale was performed by targeting msp1β gene using specific primersBAP-2/AL34S, amplifies products of size407 bp.Questionnaires based data on the characteristics of the infected animals and management strategies of the farm were collected and correlated.Results:Higher prevalence and more significant association was observed in thePCR based molecular diagnosis (P=0.00012) as compared to that inGSTBS (P=0.0288) based diagnosis with various regions under study.With respect to the regions, highest prevalence was recorded inFerozepur byPCR based diagnosis, while that inJalandhar byGSTBS examination.Similar marked significant association of thePCR based diagnosis with the age of the animals under study (P=0.00013) was observed elucidating no inverse age resistance toA. marginale in cow calves.Haematobiochemical profile of infected animals revealed marked anemia, liver dysfunction and increase globulin concentrate indicating rise in immunoglobulin level to counteract infection.Conclusions:PCR is far more sensitive in detecting the disease even in latent infection which may act as nidus for spread of anaplasmosis to susceptible animals in endemic areas.Severity of anaemia and liver dysfunction were comparable both in patent as well as latent infection indicating pathogenicity of both.