naphthoquinones and Zoonoses

Zoonotic babesiosis has received increased attention recently, due mainly to the interest in tick-borne zoonotic diseases generated by the emergence of Lyme borreliosis and to increased awareness of diagnostic and treatment difficulties associated with co-infection cases. The vast majority of European cases have been caused by Babesia divergens in splenectomised patients, and although rare, this disease is very dangerous, requiring aggressive treatment. The use of atovaquone, a recently developed anti-protozoan agent for human treatment, may be considered in future cases. Most human babesiosis caused by B. microti have occurred in the north-eastern states of the USA and can affect spleen-intact as well as asplenic patients. The majority of infections are subclinical or follow a mild chronic course, but dangerous acute infections can occur in immunocompromised patients. The role of B. microti in apparently unresponsive cases of Lyme borreliosis and treatment of co-infections require further investigation. The zoonotic potential of B. microti in Europe is still unresolved, but the vector competence of Ixodes ricinus for at least some European (and American) strains has been demonstrated.

Topics: Animals; Antiprotozoal Agents; Arachnid Vectors; Atovaquone; Babesia; Babesiosis; Europe; Humans; Ixodes; Naphthoquinones; United States; Zoonoses

Naphthoquinones and other compounds with antimycobacterial activity against Mycobacterium tuberculosis have previously been isolated from Euclea species. In this study, several constituents of Euclea natalensis and E. undulata, as well as organic extracts of the leaves, were assessed for efficacy against the zoonotic pathogen, Mycobacterium bovis. Also included in the battery of test organisms were M. bovis BCG and the fast-growing species M. smegmatis and M. fortuitum. The acetone extract of E. natalensis had potent activity against M. bovis (MIC=26 microg/ml). The naphthoquinone 7-methyljuglone was the most active compound, with an MIC as low as 1.55 microg/ml against pathogenic M. bovis. M. bovis BCG was not as susceptible to the test compounds as the pathogenic strain, but similar patterns of activity were observed between all the strains tested. M. smegmatis appeared to be a better predictor of antimycobacterial activity against pathogenic M. bovis (and M. tuberculosis), while MIC values obtained using M. fortuitum correlated well with those of M. bovis BCG.

Topics: Animals; Anti-Bacterial Agents; Cattle; Ebenaceae; Microbial Sensitivity Tests; Mycobacterium; Mycobacterium bovis; Mycobacterium fortuitum; Mycobacterium smegmatis; Naphthoquinones; Plant Extracts; Plant Leaves; Structure-Activity Relationship; Zoonoses