Diarrhea commonly affects international travelers. Episodes are usually short-lasting, but in some patients, symptoms may persist. Clostridium difficile infection should be excluded in travelers with prolonged disease. We report what is, to our knowledge, the first reported study of patients with C. difficile-associated diarrhea after receipt of antibiotic treatment for traveler's diarrhea.
Populations of T. allius increased to levels nine times higher in Glurk tobacco plants infected with California tobacco rattle virus than in healthy plants of the same variety and age. Populations of T. christiei increased with applications of Hoagland's nutrient solution diluted up to 50-percent concentration, whereas population densities were low at the highest concentration (100 percent), and in water alone. Trichodorus allius did not seem to be affected to a large extent by similar applications of Hoagland's nutrient solution. Soil type influenced populations of T. allius; lighter soils were conducive to development of higher populations while soil, coarse sand, and white quartz sand used separately were not favorable for reproduction. Temperature proved to be one of the most important ecological factors in nematode reproduction. The optimum temperatures for the reproduction of each species was as follows: T. christiei, 16° to 24° C; T. porosus, 24° C; and. T allius, 21° to 24° C. Extremes of temperatures at which the different species could reproduce also varied. Populations of T. christiei were affected by an undetermined disease or condition which seemed to slow movement but did not have any apparent effect on rate of reproduction. Host ranges of three species of Trichodorus were studied. All three nematode species seemed to be polyphagous because 90 percent, 90 percent and 95 percent of the plant species tested were hosts of T. christiei, T. porosus, and T. allius, respectively. Twenty-five plant species were tested for T. porosus, 50 for T. christiei and 38 for T. allius. A method is described for keeping populations of T. allius alive in water for extended periods of time.
The reniform nematode which comprises five described and several undescribed species has been recognized as a dangerous plant parasite. It is undoubtedly one of the most common nematode types in our soils and its populations are usually very high. It has been found associated with most of our agricultural crops including pineapple, coffee, pigeonpea, tobacco, sugarcane, ornamentals, and vegetables. Increasing interest in the study of this parasite has suggested the existence of several other species which still remain undescribed. In Puerto Rico, it is now evident that several species are present. This statement is based on differences observed in relation to morphological and pathogenic characteristics among different populations. A list of 201 different host plants from 15 countries, including Puerto Rico and Caja de Muertos, an adjacent Island south of Puerto Rico, is given. Most of them are the result of field observations, but in many cases the susceptibility of the host has been corroborated on greenhouse inoculation trials. Eighty-nine host plants were found in Puerto Rico, 15 of which are new hosts to Rotylenchulus spp., and 74 to R. reniformis. Differences in degrees of susceptibility have been recognized, pigeonpea being the most susceptible, and ornamental crotalaria only a carrier. In Puerto Rico, the nematode has been located in 40 localities in some of which several plants have been found to be hosts. Humidity, elevation, temperature, and soil pH do not seem to be limiting factors in relation to the occurrence and distribution of the nematode. It occurs more in loamic soils but clay or sandy soils with little organic matter harbor large numbers if a suitable host plant is present. A general list of publications regarding this nematode citing 89 papers is also included.
In a greenhouse experiment, a population consisting of 1,500 Pratylenchus zeae in 20-cm pots were pathogenic on sorghum, and suppressed top and root growth. Pronounced necrosis of the roots resulted. Top growth was retarded by combinations of P. zeae-Curvularia spp., P. zeae-Fusarium moniliforme, P. zeae-Rhizoctonia solani, and P. zeae-Macrophomina sp., and by F. moniliforme and R. solani, alone. All nematode-fungi combinations and all fungi alone suppressed root growth. The combination P. zeae-Curvularia spp. produced most damage. P. zeae-R. solani, Curvularia spp., and F. moniliforme produced severe necrosis of sorghum roots. An initial inoculum of 750 P. zeae in 20-cm pots was not pathogenic on sorghum in a second experiment. Only the combination of P. zeae-F. moniliforme affected the fresh root weights; dry root weights were retarded significantly by P. zeae-F. moniliforme and by F. moniliforme, alone. The intensity of necrosis also varied with the different inocula.
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