Packed cell volume and bone marrow cytological responses in Trypanosoma vivax-induced acute trypanosomosis in Nigerian Sokoto Red goats

Bone marrow responses have been identified as key determinants of trypanotolerance in cattle as they determine the ability for hemopoietic cell regeneration and control of anemia. However, not much is known about such responses in Nigerian breed of goats known to show different susceptibilities to trypanosome infections. Early bone marrow events associated with pathogenesis of Sokoto Red goats to Trypanosoma vivax were investigated in six goats to assess their role in susceptibility of this goat breed to trypanosomiasis. A total of six Sokoto Red goats of mixed sexes were used. While four of the goats randomly selected were infected with Trypanosoma vivax, the remaining two served as control. The parameters examined included packed cell volume (PCV) and differential bone marrow cytology. Cytological changes in the bone marrow of goats with acute trypanosomosis were compared to the controls. T. vivax caused an acute disease course in the goats resulting to mild drop in PCV and death 2–3 weeks post infection (PI). Associated bone marrow (BM) cytological changes were characterized by moderate erythroid hyperplasia with a resultant lower myeloid:erythroid (M:E) ratio, while the granulocytic maturation rate was 3.15 ± 0.6 and 2.42 ± 0.0 for infected and control animals, respectively. However, significant macrophage (MC) numbers (hyperplasia) were detected in the BM of the infected group. Most of the MCs phagocytized mature red blood cells (RBC) and band or mature white blood cells (WBC) only while no MC phagocytized immature cells. The MCs in BM of control goats phagocytized no blood cells. The study confirmed that mature blood cells form the first cell types to be phagocytized by MCs of BM in the pathogenesis of anemia in T. vivax-infected Sokoto Red goats while early onset of MC hyperplasia and erythrophagocytosis are indicators of susceptibility to trypanosomosis in this breed of goats and perhaps other susceptible ruminants.