The pathogenic potential of endophytic Botryosphaeriaceous fungi on Terminalia species in Cameroon

In Cameroon, native Terminalia spp. represent an important component of the forestry industry, but limited information is available regarding the fungal pathogens that affect them. The Botryosphaeriaceae are endophytic fungi and latent pathogens that can result in wood stain, cankers, die‐back and death of trees, particularly when trees are under stress. The aim of this study was, therefore, to identify and characterize the Botryosphaeriaceae occurring as endophytes of Terminalia spp. in Cameroon, as part of a larger project to identify potential pathogens of these trees in the country. Samples were collected from three Terminalia spp. in the Central, Southern and Eastern Regions and the resultant Botryosphaeriaceae were identified using morphology and DNA sequence comparisons for the ITS and tef 1‐α gene regions. Furthermore, inoculation trials were conducted to consider the relative pathogenicity of the isolates collected. The majority of isolates (88%) represented species of Lasiodiplodia, including L. pseudotheobromae, L. theobromae and L. parva. The remaining isolates were identified as Endomelanconiopsis endophytica. Pathogenicity trials on young T. mantaly and T. catappa trees revealed that L. pseudotheobromae was the most pathogenic species followed by L. theobromae.     

Tick- and flea-borne rickettsial emerging zoonoses

Between 1984 and 2004, nine more species or subspecies of spotted fever rickettsiae were identified as emerging agents of tick-borne rickettsioses throughout the world. Six of these species had first been isolated from ticks and later found to be pathogenic to humans. The most recent example is Rickettsia parkeri, recognized as a human pathogen more than 60 years after its initial isolation from ticks. A new spotted fever rickettsia, R. felis was also found to be associated with fleas and to be a human pathogen. Similarly, bacteria within the family Anaplasmataceae have been considered to be of veterinary importance only, yet three species have been implicated in human diseases in recent years, including Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis, Anaplasma phagocytophilum, the agent of human anaplasmosis (formerly known as "human granulocytic ehrlichiosis agent", E. equi and E. phagocytophila), and finally Ehrlichia ewingii, which causes granulocytic ehrlichiosis in humans. We present here an overview of the various tick- and flea-borne rickettsial zoonoses described in the last 20 years, focusing on the ecological, epidemiological and clinical aspects.     

Poultry, pig and the risk of BSE following the feed ban in France--a spatial analysis

A spatial analysis was carried out in order to analyse the reason why the risk of Bovine Spongiform Encephalopathy (BSE) was spatially heterogeneous in France, during the period following the feed ban of Meat and Bone Meal to cattle. The hypothesis of cross-contamination between cattle feedstuff and monogastric feedstuff, which was strongly suggested from previous investigations, was assessed, with the assumption that the higher the pig or poultry density is in a given area, the higher the risk of cross-contamination and cattle infection might be. The data concerned the 467 BSE cases born in France after the ban of meat and bone meal (July 1990) and detected between July 1st, 2001 and December 31, 2003, when the surveillance system was optimal and not spatially biased. The disease mapping models were elaborated with the Bayesian graphical modelling methods and based on a Poisson distribution with spatial smoothing (hierarchical approach) and covariates. The parameters were estimated by a Markov Chain Monte Carlo simulation method. The main result was that the poultry density did not significantly influence the risk of BSE whereas the pig density was significantly associated with an increase in the risk of 2.4% per 10 000 pigs. The areas with a significant pig effect were located in regions with a high pig density as well as a high ratio of pigs to cattle. Despite the absence of a global effect of poultry density on the BSE risk, some areas had a significant poultry effect and the risk was better explained in some others when considering both pig and poultry densities. These findings were in agreement with the hypothesis of cross-contamination, which could take place at the feedstuff factory, during the shipment of food or on the farm. Further studies are needed to more precisely explore how the cross-contamination happened.     

Epidemiology of microsporidiosis: sources and modes of transmission

Microsporidia are single-celled, obligate intracellular parasites that were recently reclassified from protozoa to fungi. Microsporidia are considered a cause of emerging and opportunistic infections in humans, and species infecting humans also infect a wide range of animals, raising the concern for zoonotic transmission. Persistent or self-limiting diarrhea are the most common symptoms associated with microsporidiosis in immune-deficient or immune-competent individuals, respectively. Microsporidian spores appear to be relatively resistant under environmental conditions, and species of microsporidia infecting humans and animals have been identified in water sources, raising concern about water-borne transmission. Sensitive and specific immunomagnetic bead separation and PCR-based methods are being developed and applied for detecting microsporidia in infected hosts and water sources for generating more reliable prevalence data. The most effective drugs for treating microsporidiosis in humans currently include albendazole, which is effective against the Encephalitozoon species but not against Enterocytozoon bieneusi, and fumagillin, which has broader anti-microsporidia activity but is toxic in mammals, suggesting a need to identify better drugs. Strategies to capture and disinfect microsporidia in water are being developed and include filtration, coagulation, chlorination, gamma-irradiation, and ozonation.     

Evaluation of porfimer sodium in dogs and cats with spontaneous tumors

The effect of photodynamic therapy is a function of several variables, including selective retention of the drug in tumor tissue with reduced drug concentration in surrounding normal tissue. A study was designed to determine the pharmacokinetic profile and variability of porfimer sodium in dogs and cats with spontaneous tumors and to thereby determine the optimal timing of its photoactivation in these species. The results of this study indicate that there is marked variability among species in the distribution of porfimer sodium between highly proliferating tissues, which requires careful attention in the design of human and veterinary application of photodynamic therapy with porfimer sodium, as determined in rodent models.     

Is acetyl/butyrylcholine specificity a marker for insecticide‐resistance mutations in insect acetylcholinesterase?

Substrate specificity has been widely studied in vertebrate cholinesterases and it has been shown that two phenylalanines in the acyl pocket of acetylcholinesterase govern the acceptance of the acetyl/butyryl moiety of the choline esters. As an insecticide‐resistance mutation has been evidenced in the acyl pocket of Drosophila melanogaster and Musca domestica acetylcholinesterase we investigated the possibility of linking changes in acetyl/butyrylthiocholine specificity with mutations in insect acetylcholinesterase. We thus analyzed the effect of 28 mutations in Drosophila enzyme on acetyl/butyrylthiocholine, N‐methyl/N‐propyl‐carbamates and ethyl/methyl‐paraoxon preference. It appeared that the highest changes on acetyl/butyrylthiocholine and N‐propyl/N‐methyl‐carbamates preference were due to mutations in the acyl pocket. Nevertheless, other insecticide‐resistance mutations, not located in the acyl pocket, also modified these substrate preferences. Moreover, the effect of mutations in the acyl pocket was hidden when some other insecticide‐resistance mutations were combined in the enzyme. Consequently, acetyl/butyrylthiocholine preference alteration cannot be used as a marker to localize a mutation in the insect AChE. © 2000 Society of Chemical Industry     

The Leptosphaeria maculans – Leptosphaeria biglobosa species complex in the American continent

Stem canker of oilseed rape (canola, Brassica napus ) is associated with a species complex of two closely related fungal species, Leptosphaeria maculans and L. biglobosa . Of these, L. maculans is the most damaging and develops gene-for-gene relationships with the host . Here, a wide scale analysis of the L. maculans - L. biglobosa species complex was performed throughout the American continent (23 locations from Chile to Canada) plus several locations in Western Australia for comparison purposes, based on a collection of 1132 isolates from infected tissues of a susceptible cultivar. Fungal species were discriminated on the basis of morphological, phytopathological and molecular criteria and showed that L. biglobosa was closely associated with L. maculans in most of the locations. Multiple gene phylogeny using sequences of ITS, actin and β-tubulin confirmed the prevalence of the L. biglobosa 'canadensis' sub-clade in Canada, whereas up to three different sub-clades of L. biglobosa were found in Georgia (USA). Race structure of L. maculans was investigated using a combination of pathogenicity tests and PCR amplification of avirulence alleles AvrLm1 , AvrLm4 and AvrLm6 . Three contrasting situations were observed: (i) race structure in Ontario, Chile and Georgia was related to that of European and Western Australian populations, with a low race diversity; (ii) only one race was found in Mexico, and not found outside of this country; (iii) a large diversity of races was observed in central Canada (Manitoba, Alberta and Saskatchewan) with very specific features including maintenance of avirulence alleles absent from Europe, absence of the AvrLm7 allele common in Europe (or eastern Canada) and wide location-to-location variability.     

Neutrophil myeloperoxidase measurements in plasma, laminar tissue, and skin of horses given black walnut extract

OBJECTIVE: To compare measurements of myeloperoxidase (MPO) in plasma, laminar tissues, and skin obtained from control horses and horses given black walnut heartwood extract (BWHE). ANIMALS: 22 healthy 5- to 15-year-old horses. PROCEDURES: Horses were randomly assigned to 4 groups as follows: a control group given water (n = 5) and 3 experimental groups given BWHE (17) via nasogastric intubation. Experimental groups consisted of 5, 6, and 6 horses that received BWHE and were euthanatized at 1.5, 3, and 12 hours after intubation, respectively. Control horses were euthanatized at 12 hours after intubation. Plasma samples were obtained hourly for all horses. Laminar tissue and skin from the middle region of the neck were harvested at the time of euthanasia. Plasma and tissue MPO concentrations were determined via an ELISA; tissue MPO activity was measured by use of specific immunologic extraction followed by enzymatic detection. RESULTS: Tissues and plasma of horses receiving BWHE contained significantly higher concentrations of MPO beginning at hour 3. Laminar tissue and skin from horses in experimental groups contained significantly higher MPO activity than tissues from control horses. Concentrations and activities of MPO in skin and laminar tissues were similar over time. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, BWHE administration causes increases in MPO concentration and activity in laminar tissue and skin and the time of increased MPO concentration correlates with emigration of WBCs from the vasculature. These findings support the hypothesis that activation of peripheral WBCs is an early step in the pathogenesis of acute laminitis.