A longitudinal study was conducted to assess the clinical manifestation, response to treatment, and biochemical alterations to bovine trypanosomosis in some selected Local Government Areas of Niger State. A total of 343 cattle from thirty nine (39) herds were examined for infection with trypanosomes. Parasitological, haematological and biochemical tests were carried out on their blood and serum samples. Clinical signs, changes in haematological and biochemical values were monitored post treatment with diminazene aceturate and isomethamidium chloride. The most prevalent clinical signs observed were emaciation (75%), weakness (71%) intermittent anorexia (65%), pale mucous membrane (58%), epiphora (45%), and dark/rough hair coat (41%). Three species of trypanosomes were identified in the infected animals, Trypanosoma vivax (5.5%), T. congolense (5.5%), and T. brucei (2.0%). The mean body weights of infected animals (257.94 ± 74.13kg) were significantly lower than that of the control (386.96 ± 62.69kg). The mean rectal temperature of infected animals (39.82 ± 1.79ºC) differed significantly from the control (38.490.84ºC) (P<0.05). The mean PCV (23.27 ± 6.82%), platelet (93.23 ± 42.02 x103 μl), and total leukocyte counts (4.40 ± 1.64×103 μl) of infected cattle before treatment were significantly lower than those of the control (32.47 ± 8.35%, 209.67 ± 55.75 x103 μl and 8.14 ± 3.34 x103 μl respectively). Lymphocyte counts (64.64 ± 12.19%) were significantly higher in the infected cattle when compared to the control (58.19 ± 15.29%). The mean neutrophils count (32.62 ± 12.25%) of the infected cattle was significantly lower than the control (39.46 ± 15.05%). The mean values of Alanine amino transferase (34.62 ± 20.57 IU/L), alkaline phosphatase (105.48 ± 37.97 IU/L), Creatinine kinase (265.71 ± 21.25 IU/L) of the infected cattle were significantly higher than the control (16.60 ± 3.73 IU/L, 65.60 ± 18.90 IU/L, and 254.12 ± 11.32 IU/L respectively). The mean total proteins (51.50 ± 18.28 mg/dL), glucose (31.94 ± 13.68 mg/dL), cholesterol (2.62 ± 1.33 mg/dL) of the infected cattle were significantly lower than the control (77.20 ± 14.46 mg/dL, 46.80±13.59 mg/dL, 3.25 ± 1.66 mg/dL) respectively. The levels of albumin (24.84 ± 8.31 mg/dl) and globulins (29.34 ± 15.31 mg/dl) of the infected cattle were significantly lower than the control (27.60 ± 6.73 mg/dL and 49.80 ± 15.05 mg/dL) respectively. The mean triglycerides levels of the infected cattle (2.32 ± 1.08 mg/dL) were significantly higher than the control (1.90 ± 0.58 mg/dL). The mean levels of sodium (111.82 ± 28.84 mg/dL), chloride (91.76 ± 25.59 mg/dL) and bicarbonates (17.46 ± 6.76 mg/dL) of the infected cattle were significantly lower than the control (127.80 ± 34.95 mg/dL, 98.60 ± 19.48 mg/dL, and 20.6012.58 mg/dL) respectively. The levels of calcium (2.98 ± 0.84mg/dL), iron (1.55 ± 0.60 mg/dL), copper (0.49 ± 0.36 mg/dL) and zinc (2.08±1.42 mg/dL) were significantly lower in infected cattle compared to the values of the control (4.16 ± 0.54 mg/dL, 4.45 ± 2.07 mg/dL, 0.81 ± 0.08 mg/dL, and 7.88 ± 2.52 mg/dL) respectively. All values were held at P≤0.05 confidence interval. This study has suggested for the first time the clinical signs of natural cases of trypanosomosis in cattle in selected Local Government Areas in Niger State. Diminazene aceturate and isomethamidium chloride were effective in the treatment of naturally occurring trypanosomosis. However, relapse infection was observed using both drugs. The study has shown that the current trend in diagnosis, treatment and management of trypanosomosis is important to avoid treatments that will potentiate drug resistance. Further work should be done to establish the parasitological and pathological bases for each of the clinical signs that were observed in this study.



1.1 Background to the study

Trypanosomosis is a complex disease caused by trypanosomes, a group of unicellular protozoan parasites found in the blood and other tissues of vertebrates including livestock, wildlife (Tesfaye, 2002) and man (Franco et al., 2014). The disease is commonly known as “Nagana”, “Samore” or Tsetse fly disease in the bovines (Radostits et al., 2006), and sleeping sickness in man (Franco et al., 2014).The disease is characterized by anorexia, anaemia, diarrhoea, excessive epiphora, emaciation, weakness and eventual death, in addition to leucopaemia, thrombocytopaenia, serum biochemical changes and lesions in some tissues and organs (Igbokwe, 1989; Esievo and Saror, 1991; Uilenberg, 1999; Rodosttis et al., 2006).

The most important trypanosome species infecting livestock are Trypanosoma (T) congolense, T. vivax and T. brucei, primarily for ruminants (Igbokwe, 1995; Onyiah, 1997; Takeet et al., 2013) and T. simiae which primarily infects pigs (Sarkey, 1998). Trypanosoma evansi and T. equiperdum infects equidae (Moloo et al., 2000; Getachew, 2005; OIE, 2013) while Trypanosom brucei rhodesiense and T. brucei gambiense are known to infect man (Dumas et al., 1999; Franco et al., 2014). Trypanosomes are commonly transmitted biologically by tsetse flies (Glossina SPP), but some cases of mechanical transmission by other haematophagus flies and trans-placental transmission have been reported (Ikede and Losos 1972; Ogwu et al., 1986).

Trypanosomosis is widespread and endemic in Nigeria, occurring in all areas infested by tsetse flies (Onyiah et al., 1983) as well as the tsetse-free arid zones of the north that is infested by other biting flies (Nawathe et al., 1988, 1995; Ahmed et al., 1994).

The tsetse flies are found between latitudes 14ºN and 29ºS covering about 10 Million km² stretching across 37 countries in Africa (Seifert, 1996; WHO, 1998; Mulumba, 2003).

1.2 Statement of the Research Problem

The annual production losses due to Africa Animal Trypanosomosis (AAT) morbidity and mortality are valued at $4.5 billion across Africa while the indirect annual costs of AAT are estimated to be $134 billion (Kristjanson et al., 1999; Fadiga et al., 2013). In the Sub Saharan Africa over 3 million cattle and other domestic livestock are lost annually through deaths caused by trypanosomosis (ILRAD, 1990; Mulumba, 2003; Abenga et al., 2003; FAO, 2005). The disease costs the Nigerian economy $135 million per annum due to its negative effects on weight gain, growth rate, milk yield, reproduction in cattle and discouragement of the use of draught animals in arable farming (Omotainse et al., 2004).

Trypanosomosis has been shown to reduce calving rates by 11-20% and increases calf mortality by 10-20% in susceptible breeds of cattle. Similarly, it is known to reduce milk off take in trypanotolerant breed of cattle by 10-20% and off take for sale or slaughter by 5–30%. The work performance of draught oxen in susceptible cattle can drop by 38% in high risk areas (PAAT, 2000; Shaw, 2004). Generally, trypanosomosis reduces total stock of livestock by 10–60% (Kristjanson et al., 1999; PAAT, 2000; Gilbert et al., 2001) with consequent reduction in meat and milk output by 50% and reduction in total agricultural production by 2–10 per cent (PAAT, 2000). Trypanosomosis is one factor that has constrained the development of specialized dairy enterprises in sub Saharan Africa (Swallow, 2000). The overall impact of the disease extends from restricted access to fertile and cultivable areas, imbalances in land use and exploitation of natural resources and compromised growth and diversification of crop-livestock production systems (Mattioli et al., 2004).

1.3 Justification of the Study

The management of clinical disease due to trypanosomes through diagnosis and treatment remains difficult under field conditions (Nantulya, 1990; Schlater and van den Bossche, 2004), because of its protean manifestations and lack of pathognomonic signs (Eisler et al., 2004; Rodostits et al., 2006).Simultaneous infections with more than one Trypanosoma species (Nyeko et al., 1990) and their ability to co-infect with other parasites (Babesia spp., Theileria spp., Anaplasma spp., Ehrlichia spp., and helminths) (Thumbi et al., 2014) further complicate the prognosis and clinical manifestations of the disease (Van Wyk et al., 2014). It has also been estimated that close to 50% of all cases of trypanosomosis are not diagnosed and a large proportion of the infected animals remained untreated (Picozzi et al., 2002). Poor and inadequate tools for the diagnosis of the disease in the field make it difficult to conclude which clinical signs are attributable to a given parasite (Machila, 2004).

There is the need therefore to document clinical signs due to natural Trypanosoma infection with the view aiding field personnel and farmers in the recognition of animals suffering from the disease in the field to enable rapid and accurate diagnosis of the disease and subsequent monitoring of the incidence of infection. This would assist in management decisions; provide basis for disease surveillance, monitoring and control programmes. It will also assist in the control and eradication of tsetse and trypanosomosis which would eventually benefit and promote human and livestock health, diversify agricultural production and allow for optimum exploitation of the abundant fodder and water resources for large scale livestock production.

1.4 Aim of the Study

The aim of the study was to determine the clinical manifestations, blood parameters, response to treatment of naturally occurring cases of bovine trypanosomosis in Niger State, Nigeria.

1.5 Objectives of the Study

The objectives of the study were to:

i. Determine the species of trypanosomes infecting cattle in Niger State

ii. Determine the clinical signs naturally infected cattle manifest in Niger State, Nigeria;

iii. Determine the haematological and serum biochemical parameters in the naturally infected cattle in Niger State, Nigeria;

iv. Evaluate the treatment response to selected trypanocides by naturally infected cattle during the study period in Niger State, Nigeria.

1.6 Research Questions

i. What are the species of trypanosomes infecting cattle in Niger State?

ii. What are the commonly observed clinical signs that naturally infected cattle manifest in Niger State, Nigeria?

iii. What are the haematological and serum biochemical profiles of natural trypanosomosis in cattle in Niger State, Nigeria?