Comparative serum biochemical changes in mongrel dogs following single and mixed infections of Trypanosoma congolense and Trypanosoma brucei brucei.

The serum activities of alkaline phosphatase (AP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the serum levels of conjugated bilirubin (CB), blood urea nitrogen (BUN) and creatinine were studied following single and mixed infections of mongrel dogs with Trypanosoma congolense and Trypanosoma brucei brucei. Twenty mongrel dogs of both sexes aged between 3 and 6 months, and weighing between 2.5 and 5.9 kg were used for the study. The dogs were kept in clean metal cages in a fly-proof house and were fed and given water ad libitum. The twenty dogs were divided into four groups of five dogs each. Group I dogs were uninfected control, group II were infected with T. congolense, group III were infected with T. brucei brucei and group IV were infected with both T. congolense and T. brucei brucei. Each dog in the infected groups II and III was inoculated intraperitonealy (i/p) with 1.0 ml of PBS diluted blood containing 1.0×10(6) trypanosomes whereas each infected dog in group IV (mixed infection) was inoculated with 0.5 ml of the PBS diluted blood containing 0.5×10(6)T. congolense and 0.5 ml of the PBS diluted blood containing 0.5×10(6)T. brucei brucei i/p. Parasites were detectable in the blood of the infected dogs in groups II, III, and IV 10-13 days post infection (PI) with the mean pre-patent period (PP) of 12, 10, and 11 days respectively. Trypanosome infection caused a significant (P<0.05) increase in the serum activities of AP, ALT, AST and the serum levels of creatinine, CB, and BUN. The significant increases in the serum levels of CB, BUN, and creatinine and serum activities of AP and AST became noticeable from day seven PI in all the infected groups whereas that of ALT became noticeable from day 14 PI and increased continuously until the experiment was terminated. These increases however did not differ significantly (P>0.05) between the infected groups in most cases. It was thus concluded that single or mixed infection of mongrel dogs with T. congolense and T. brucei brucei resulted in significant increases in the serum activities of AP, AST, ALT and serum levels of creatinine, CB and BUN which in most cases did not differ significantly (P>0.05) among the infected groups.

Comparative haematological study of single and mixed infections of mongrel dogs with Trypanosoma congolense and Trypanosoma brucei brucei.

The haematological effects of single and mixed infections of Trypanosoma congolense and Trypanosoma brucei brucei were compared in experimentally infected mongrel dogs. Twenty mongrel dogs of both sexes aged between 3 and 6 months, and weighing between 2.5 and 5.9 kg were used for the study. The dogs were kept in clean metal cages in a fly-proof house and were adequately fed and given water ad libitum. The twenty dogs were divided into four groups of five dogs each. Group I dogs were uninfected control, group II dogs were infected with T. congolense, group III dogs were infected with T. brucei brucei and group IV dogs were infected with both T. congolense and T. brucei brucei. Parasitaemia occurred in the infected dogs in groups II, III, and IV; 10-13 days post-infection (PI) with the mean pre-patent period (PPP) of 12, 10, and 11 days respectively. Mixed infection persisted throughout the duration of the experiment. T. brucei predominated T. congolense in the mixed infection constituting about 70% of the trypanosomes. The significant (P<0.05) decrease in the mean haemoglobin concentration (Hb) and packed cell volume (PCV) caused by the infection did not differ significantly (P>0.05) between the infected groups. Also the significant (P<0.05) reduction in the total white blood cell count (TWBC) caused by the infection did not differ significantly (P>0.05) between the infected groups. The decline in the total WBC count was due primarily to significant (P<0.05) reduction in the lymphocyte counts of the infected dogs. It was thus concluded that single or mixed infection of mongrel dogs with T. congolense and T. brucei brucei resulted in anaemia and leucopenia which did not differ significantly (P>0.05) among the infected groups.

Action of isometamidium chloride on the insect vector form of Trypanosoma vivax.

The effect of isometamidium chloride upon developing and mature Trypanosoma vivax occurring in Glossina palpalis palpalis flies was evaluated. Newly emerged G p palpalis flies were infected with T vivax by allowing them to feed on parasitaemic animals. Two experiments were conducted and in each the flies were divided into two groups. One group of infected flies was fed in vitro through a membrane on defibrinated cow blood containing isometamidium chloride at 0.1 mg ml-1, after which they were dissected and examined for trypanosomes, and the other group was fed in the same way on unmedicated blood. The results showed that out of a total number of 129 flies which fed on medicated blood, none was infected, while 55 out of 127 flies which fed on unmedicated blood were infected. The results indicate that isometamidium chloride eliminated the insect vector form of T vivax. These findings are of potential significance in the control of trypanosomiasis in the field, particularly in the operation of the sterile insect technique.

Comparative study of the susceptibility to infection with Trypanosoma simiae of Glossina morsitans and G. tachinoides.

The susceptibility to infection with Trypanosoma simiae of Glossina morsitans and G. tachinoides was compared. A total of 592 G. tachinoides and 348 G. morsitans were used in trying to transmit T. simiae to pigs. G. morsitans were very good at transmitting T. simiae infection to pigs while G. tachinoides were very poor. The epidemiological importance of the results is discussed.

The effect of isometamidium chloride on Trypanosoma vivax occurring within the insect vector (Glossina).

The effect of chemoprophylaxis on developing and mature Trypanosoma vivax in Glossina tachinoides and G. palpalis palpalis was evaluated. Newly emerged G. tachinoides and G.p. palpalis flies were infected with T. vivax by allowing them to feed on parasitaemic animals. Three experiments were conducted and in each the flies were divided into two groups. One group of infected flies was fed on animals treated 1 day previously with isometamidium (1 mg/kg body wt. in a 4% soln.) after which the surviving flies were dissected and examined for trypanosomes. The other group was fed on untreated animals. Out of a total number of 123 flies which fed on treated animals, none were found to be infected, while 51 of 127 flies which fed on untreated animals were infected. It was concluded that prophylactic treatment of animals with isometamidium would eliminate T. vivax infections from the insect vector. The potential significance of this finding in the control of trypanosomiasis in the field is discussed.

Pathogenesis of anaemia in hamsters infected with Leishmania donovani.

The development of anaemia was studied in hamsters infected with Leishmania donovani. Haematocrit studies as well as erythrocyte survival studies using radioactive chromium (51Cr), gave evidence of a progressive anaemia during the course of infection. The erythrocytes were positive in direct antiglobulin tests using antisera to IgG and complement C3. Moreover, erythrophagocytosis as well as increased deposits of haemosiderin in the liver and the spleen, particularly in the areas of proliferating macrophages, were demonstrated. It would appear that the erythrocytes adsorb immune complexes on their surfaces and become liable to enhanced phagocytosis by the macrophages of the liver and the spleen.