Generally, aspergillosis in chickens is an acute disease causing high mortality in the first few days of life. The disease in some cases can be chronic, with lesions in the lungs, air sacs, and joints . Evidence of clinical signs associated with A. fumigatus infection was quite evident in this study, which is in agreement with literature. Our data indicated that the crude extract of L. alata has certain level of activity against aspergillosis in broiler chicks and could serve as model for the development of safer and effective anti-Aspergillus agents. Plant drugs have been assumed to be safe. However, in recent times, there is evidence that many plants used as food or as medicine can be potentially toxic [24, 25]. All drugs can produce harmful as well as beneficial effects, hence the need for toxicity testing of any substance intended for development into drug for human or animal use . Investigation of the acute toxicity is the first step in the toxicological investigations of an unknown substance . The index of the acute toxicity is the lethal dose 50 (LD50). However, the LD50 is not regarded as a biological constant, since differing results are obtained on repetition . The OECD guidelines for testing chemicals (2000) for toxicity were adapted in testing the safety of the extract of Loxostylis alata. The method is not intended to allow the calculation of a precise LD50, but does allow for the determination of defined exposure ranges where lethality is expected since death or appearance of toxic signs of a proportion of the animals is still the major endpoint of this test. The extract was toxic at the dose of 300 mg/kg based on its effects on different parameters measured and clinical signs noticed on the experimental chicks. Dose is an important factor in drug poisoning and most drugs cause clinical signs of poisoning when administered at relatively high dose .
At lower doses (200 mg/kg and below) the extract had no apparent toxic effects. Although, the chicks treated with 50 and 200 mg/kg had lower weight gain than those in the control group, their weights were within the normal growth rate for broiler chickens expected for the particular research site and reported in literature [29, 30]. The reason for the DMSO treated healthy birds, on average, out-performing the historical growth reported for the facility is not known at this stage.
Clinical signs of aspergillosis observed in our study included ruffled feathers, gasping, dyspnoea, dullness, green watery diarrhoea and anorexia. These signs are in agreement and confirmed the clinical signs observed in previous studies . Although ascites and blindness were observed by Julian and Goryo (1990) and Akan et al. (2002), respectively, we did not observe these clinical features in our study [31, 32]. Chicks in this study started dying 3 days p.i. with mortality reaching as up to 75% in the non-treated group. Furthermore, A. fumigatus was re-isolated from the lungs and airsacs of infected chicks from 3 days p.i up to 12 days p.i. Lesions were seen mainly in the lungs, liver and the airsac. From a clinical efficacy point, the presence of organisms in the lungs after treatment, with either the plant extract or the ketoconazole, may be seen as therapeutic failure. However the failure to clear the organism is most likely linked to the short duration of treatment as opposed to product failure. As such for future studies, it is recommended that treatment extend for longer periods perhaps daily for 2 weeks.
Surprisingly, A. fumigatus was isolated from the lung sample of one chick in the neutral group, which was not infected and also not treated. Since systemic infection with Aspergillus fumigatus results naturally through the inhalation of spores,  it is possible that the chicks in the neutral group were infected naturally from fungal spores inhaled in the air. However, we used a specific histological staining technique to confirm the presence of an infection, and are therefore certain that the positive result was due to contamination during post mortem examination.
Increase AST and GGT activity as well as A/G ratio are indicative of a liver injury. This was supported by the isolation of the agent from liver. In addition, there was presence of lesions on the liver. Compared with the infected untreated group with a mortality rate of 75%, in the entire infected treated group, the mortality rate reduced and death was stopped on 11th day post-infection. Treatment with extract of Loxostylis alata at doses used confer a dose related success in combating infection due to A. fumigatus in broiler chicks and that compared favourably with the reference compound (ketoconazole). Compounds administered i.p. are absorbed primarily through the portal circulation and, therefore, must pass through the liver before reaching other organs. This factor can limit the amount of drug reaching its site of action . Indeed, there are numerous examples in the literature of drugs that are less effective after i.p. administration than when given by other parenteral routes. Such examples include reserpine , phenelzine and phenipramine . It will therefore be reasonable to assume that when the extract is administered via another route that bypasses the portal circulation could result in enhanced action of the extract.