Abstract
A cross-sectional survey of trypanosome infection of pigs was carried out in three randomly selected Local Government Areas (Nsukka, Udenu and Igbo Eze South) out of the six local government areas in Enugu North Senatorial Zone. Blood samples collected at random from a total of 1800 pigs from abattoirs and farms were examined for trypanosomes using standard parasitological methods: wet film, buffy coat and Giemsa-stained thin smear preparations. The sensitivity of trypanosome isolates from infected pigs was evaluated in mice at two dose levels each of diminazene aceturate (7 and 28 mg/kg body weight) and isometamidium chloride (0.25 and 2 mg/kg) by the infection and treatment method. The effects of experimental single and mixed infections of T. brucei and T. congolense on the haematology and serum biochemistry were evaluated in groups of infected pigs. The overall prevalence of porcine trypanosomosis in the zone was 5.2 %. Trypanosoma brucei was the predominant species (84.9%) encountered, followed by T. congolense (15.1%). Prevalence of infection in Nsukka, Igbo-Eze South and Udenu LGAs, respectively, were 4.7%, 4.7%, and 4.0% in the dry season, and 5.7%, 5.7% and 6.3% in the rainy season and did not show any significant variations (p 0.05) with seasons, sex and age groups. Multiple drug resistance was prevalent in the trypanosome isolates, as all 18 isolates (16 T. brucei and 2 T. congolense) tested were resistant to both diminazene aceturate (7 mg/kg b.w) and isometamidium chloride (0.25 mg/ kg b.w,), at the low dose levels tested. Sixteen of the isolates resisted the high dose levels of diminazene aceturate (28 mg/kg b.w), while six isolates were resistant to isometamidium chloride (2 mg/kg b.w). Classical clinical manifestations of trypanosomosis that were observed in the experimentally infected pigs included pyrexia, varying degrees of anaemia, loss of body weight, and anorexia. Comparative evaluation of the haematological profile revealed significant decrease (p < 0.05) in packed cell volume, haemoglobin concentration and red blood cell counts of the infected relative to the uninfected pigs. In contrast, total white blood cell counts in infected groups was significantly (p < 0.05) higher when compared with uninfected group. All the biochemical parameters studied (alanine amino transferase, aspartate amino transferase, albumin, globulin, cholesterol and creatinine) with the exception of total protein and urea differed significantly (p < 0.05) between the xvi infected groups and uninfected control group. Serum concentrations of alanine amino transferase, aspartate amino transferase, creatinine and globulin were higher whereas albumin and cholesterol were lower in the infected groups, except for the T. congolense group whose serum cholesterol levels were not significantly (p > 0.05) different from the control group. There was no significant difference (p > 0.05) in the serum biochemistry parameters between the single and mixed infection groups. It was concluded that porcine trypanosomosis was still endemic in Enugu North Senatorial Zone and outbreaks in the area will most likely be caused by T. brucei. The prevalence of infection was neither dependent on seasons of the year nor sex and age of the pigs. Trypanosome isolates from pigs in the study area exhibited resistance to both diminazene aceturate and isometamidium chloride, the two most commonly used trypanocides in the area. This phenomenon constitutes serious threat to chemotherapeutic control of porcine trypanosomosis in particular and animal trypanosomosis in general in Enugu North Senatorial Zone. Trypanosome brucei and T. congolense as single and mixed infections brought about changes in hematology and some serum biochemical profile of the infected pigs, which could be useful in disease investigation, diagnosis and prognosis.