A serological study of Babesia caballi and Theileria equi in Thoroughbreds in Trinidad

Ninety-three (93) horses were investigated for serum antibodies to Theileria equi (T. equi) and Babesia caballi (B. caballi) using the immunofluorescent antibody test (IFAT). Seventy-seven (82.8%) horses were seropositive; 31 (33.3%) were positive to T. equi compared to 64 (68.8%) to B. caballi while 18 (19.4%) horses were seropositive to both parasites. No significant differences in antibody frequencies among females and males for either T. equi or B. caballi were noted. Differences in seropositivity to B. caballi among age groups were not significant. Antibodies to T. equi were more frequent than to B.caballi in the age group 5 years and over than in the 1-2 and 2-4 years age groups (p<0.05). Unlike T. equi antibodies, B. caballi antibodies in horses in the county of Caroni were significantly less frequent when compared to other counties (p<0.05). Of 18 (19.4%) clinically ill horses, seven (42.9%) had clinicopathological evidence of anemia. Only one-third (6 of 18) horses were positive for the parasite on Wright-Giemsa stained blood smears and anemia was present in only 2. We report here that B. caballi and not T. equi may be the more common agent of piroplasmosis in Trinidad.     

Calcium chelate is as effective as phosphite in controlling Phytophthora root rot in glasshouse trials

Species in the genus Phytophthora cause significant economic losses in crops and damage to forests and natural ecosystems worldwide. Currently, phosphite is the most effective chemical for disease management, but excessive phosphite concentrations can result in phytotoxicity in plants and the development of tolerance by the pathogen. Two newly developed metal chelates and phosphite (alone and in combination) were tested for their in vitro and in planta efficacy against Phytophthora cinnamomi. In glasshouse trials, 0.25% and 0.5% of each chemical treatment (phosphite, Ca chelate, Zn chelate) and Ca chelate + phosphite were used as a foliar application on 3-month-old seedlings of Banksia grandis (experiment not repeated) and Eucalyptus marginata, prior to inoculation with P. cinnamomi. All noninoculated control plants remained healthy, while significant root damage and reduction of dry root weights were observed for inoculated untreated plants. Individually, phosphite and Ca chelate significantly reduced root lesion development of P. cinnamomi compared to the control, with Ca chelate attaining superior results to phosphite at the same concentration. In combination, Ca chelate + phosphite had the largest reduction in root lesion development in both plant species; however, this result has not yet been replicated but did reflect previous in vitro results. The Zn chelate applications were not effective. Ca chelate has the potential to be developed as a fungicide to control Phytophthora species.     

Potassium permanganate elicits a shift of the external fish microbiome and increases host susceptibility to columnaris disease

The external microbiome of fish is thought to benefit the host by hindering the invasion of opportunistic pathogens and/or stimulating the immune system. Disruption of those microbial communities could increase susceptibility to diseases. Traditional aquaculture practices include the use of potent surface-acting disinfectants such as potassium permanganate (PP, KMnO₄) to treat external infections. This study evaluated the effect of PP on the external microbiome of channel catfish and investigated if dysbiosis leads to an increase in disease susceptibility. Columnaris disease, caused by Flavobacterium columnare, was used as disease model. Four treatments were compared in the study: (I) negative control (not treated with PP nor challenged with F. columnare), (II) treated but not challenged, (III) not treated but challenged, and (IV) treated and challenged. Ribosomal intergenic spacer analysis (RISA) and pyrosequencing were used to analyze changes in the external microbiome during the experiment. Exposure to PP significantly disturbed the external microbiomes and increased catfish mortality following the experimental challenge. Analysis of similarities of RISA profiles showed statistically significant changes in the skin and gill microbiomes based on treatment and sampling time. Characterization of the microbiomes using 16S rRNA gene pyrosequencing confirmed the disruption of the skin microbiome by PP at different phylogenetic levels. Loss of diversity occurred during the study, even in the control group, but was more noticeable in fish subjected to PP than in those challenged with F. columnare. Fish treated with PP and challenged with the pathogen exhibited the least diverse microbiome at the end of the study.     

Diversity of bacterial pathogens and their antimicrobial resistance profile among commensal rodents in Qatar

Rodents are sources of many zoonotic pathogens that are of public health concern. This study investigated bacterial pathogens and assessed their antimicrobial resistance (AMR) patterns in commensal rodents in Qatar. A total of 148 rodents were captured between August 2019 and February 2020, and blood, ectoparasites, and visceral samples were collected. Gram-negative bacteria were isolated from the intestines, and blood plasma samples were used to detect antibodies against Brucella spp., Chlamydophila abortus, and Coxiella burnetii. PCR assays were performed to detect C. burnetii, Leptospira spp., Rickettsia spp., and Yersinia pestis in rodent tissues and ectoparasite samples. Antimicrobial resistance by the isolated intestinal bacteria was performed using an automated VITEK analyzer. A total of 13 bacterial species were isolated from the intestine samples, namely Acinetobacter baumannii, Aeromonas salmonicida, Citrobacter freundii, Citrobacter koseri, Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Hafnia alvei, Klebsiella pneumoniae, Providencia stuartii, Proteus mirabilis, Pseudomonas aeruginosa, and Salmonella enterica. The majority of them were E. coli (54.63%), followed by P. mirabilis (17.59%) and K. pneumoniae (8.33%). Most of the pathogens were isolated from rodents obtained from livestock farms (50.46%), followed by agricultural farms (26.61%) and other sources (22.94%). No antibodies (0/148) were detected against Brucella spp., C. abortus, or C. burnetii. In addition, 31.58% (6/19) of the flea pools and one (1/1) mite pool was positive for Rickettsia spp., and no sample was positive for C. burnetii, Leptospira spp., and Y. pestis by PCR. A total of 43 (38%) bacterial isolates were identified as multidrug resistant (MDR), whereas A. salmonicida (n?=?1) did not show resistance to any tested antimicrobials. Over 50% of bacterial MDR isolates were resistant to ampicillin, cefalotin, doxycycline, nitrofurantoin, and tetracycline. The presence of MDR pathogens was not correlated with rodent species or the location of rodent trapping. Seven (11.86%) E. coli and 2 (22.2%) K. pneumoniae were extended-spectrum beta-lactamases (ESBL) producers. These findings suggest that rodents can be a source of opportunistic bacteria for human and animal transmission in Qatar. Further studies are needed for the molecular characterization of the identified bacteria in this study.

     

Seasonal trends in epidemiological and entomological profiles of malaria transmission in North Central Nigeria

The influence of seasonal changes on epidemiological and entomological indices of malaria transmission in North Central Nigeria was elucidated in a series of studies carried out between January 2004 and December 2009. The climate in the study area was divided into three seasonal periods namely, rainy (May-October), dry (December-March) and transitional (April and November), during which larval and adult anopheline mosquito collections were carried out and assessed for densities, sporozoite infection and parity rates and potentials for malaria transmission. The results indicated that the climate in the study area was clearly seasonal, with close similarities in the patterns of distribution of the climatic factors in the study sites. Mosquito densities, both at the adult and larval stages (i.e., 29.35 +/- 5.10 adult mosquitoes/man/night and 10.36 +/- 3.34 larvae/dip, respectively), were significantly (p<0.05) highest during the rainy season. However, while the former varied significantly in the three seasonal periods, the latter was not significantly different during the dry and transitional seasons. Malaria transmission risks, in terms of sporozoite rates and entomological inoculation rates, was significantly (p<0.05) least in the dry season (i.e., 2.89 +/- 1.25% and 0.37 +/- 0.21 infective bite/man/night, respectively) but the two variables were not significantly (p>0.05) different during the transitional and rainy seasons. Adult mosquito daily survival rate and adult longevity were least in the dry season (26.52 +/- 11.80% and 6.80 days, respectively) and significantly (p<0.05) highest during the rainy season (72.28 +/- 4.00% and 16.95 +/- 4.20 days, respectively). Parous rates of the mosquitoes and duration of sporogony had distinct distribution pattern from the other variables investigated. While, significantly highest parous rates were recorded in the transitional season (86.00 +/- 4.30%), duration of sporogony was not significantly (p>0.05) different during the three seasons. The epidemiology of urban malaria in North Central Nigeria was discussed from the view points of the these results and concluded that the findings should promote the development of informed temporally-targeted vector control programs for the area.     

An Assessment of the Biodegradation of Petroleum Hydrocarbons in Contaminated Soil Using Non-indigenous, Commercial Microbes

A study was conducted to determine the efficiency and effectiveness of two commercial microbial based bioremediation products compared to indigenous tropical microorganisms in a small-scale trial. The oil and grease content of the samples was monitored as an indication of the levels of petroleum hydrocarbon during the experiment. The indigenous enriched culture generally biodegraded the petroleum hydrocarbon to a greater extent than the commercial products and media controls early in the bioremediation process (0–5 days). However, as time progressed the extents of biodegradation were not significantly different between treatments until late in the bioremediation process (after 18 days). Of the two commercial products, one was more effective, reducing the level of oil and grease by 52.5% over the 3 week study. However, neither commercial product was able to meet the manufacturer’s stated level of 95% removal within three weeks. Commercial microbial-based bioremediation products may be used with some success in tropical environments, however location-specific trials may be required to ensure that the best commercial product is selected. As an alternative, the selective enrichment of indigenous microorganisms may result in similar performance at a reduced cost.     

Soil application of Trichoderma asperellum strains significantly improves Fusarium root and stem rot disease management and promotes growth in cucumbers in semi-arid regions

European Journal of Plant Pathology - To improve biocontrol approaches in Saudi Arabia, it is necessary to collect and screen suitable native Trichoderma strains. In this study, the biocontrol...     

The Hymenopteran parasitoid complex associated with Coniesta ignefusalis (Hampson) (Lepidoptera: Crambidae) on Pearl millet in Mali

Phytoparasitica - Moths of Coniesta ignefusalis (Hampson) were collected by automatic light traps on millet field near Bamako in 2018. The light trap data shows three periods of moth flight. The...