Evaluation of pyrimethamine and mefloquine antimalarial drugs for the treatment of albino mice co-infected with toxoplasma - gondii and Schistosoma mansoni

ABSTRACT

The mainstay of this work is to elucidate the prophylactic and curative effects of using two different antimalarial drugs [Pyrimethamine+ Mefloquine] in experimental Toxoplasma gondii infection on top of chronic schistosomiasis mansoni. A group of forty Swiss albino mice chronically infected [each with 80 S. mansoni cercariae and kept for seven weeks], was used in the experiment. This group was further subdivided into three subgroups. Subgroup I control group which is further subdivided into two smaller subgroups. Subgroup I [A] control infected untreated animals given S. mansoni cercariae by body immersion and kept for seven weeks [the time needed for the infection to become chronic]. Subgroup I [B] included control doubly infected untreated animals. S. mansoni infected mice were given 100 tachyzoites of T. gondii via an intraperitoneal cannula seven weeks post schistosoma mansoni infection, then sacrificed four days later. Subgroup II prophylactic group, included chronic S. mansoni infected mice [for 7 weeks], given the oral drug combination [Pyrimethamine 25 mg/Kg body weight + Mefloquine 100 mg/ Kg body weight] single daily dose for 14 successive days before Toxoplasma infection. Subgroup III chronic S. mansoni infected mice for 7 weeks, treated 24 hours post Toxoplasma infection with the same oral drug combination [Pyrimethamine 25 mg/Kg body weight + Mefloquine 100 mg/Kg body weight] single daily dose for 14 successive days. Sacrifice was performed two weeks post Toxoplasma infection. The efficacy of both drugs was assessed by worm and tissue egg load and oogram pattern for schistosomiasis, and animal survival, and collecting peritoneal exudates from succumbing mice, then calculation at random for the presence of Toxoplasma gondii parasites. It was found that doubly infected [chronic seven weeks old Schistosoma mansoni followed by Toxoplasma gondii infections] untreated mice died between 6 and 8 days post Toxoplasma infection, while treatment markedly prolonged the survival time of experimental animals. Again, Daraprim and Mefloquine failed to significantly reduce the total number of worms when compared to the infected untreated control group. Moreover, there was complete absence of tachyzoites in the post infection treated group, in comparison with the control infected untreated animals. These data were less conspicuous in the group treated 14 days prior to Toxoplasma infection. This study may be of value in endemic areas, where double parasitic infestation with schistosomiasis and toxoplasmosis is a common occurrence