Preliminary assessment of the potential role of urbanization in the distribution of carbamate and organophosphate resistant populations of Culex species in Ghana

Background: Besides its role as a pathogen vector, Culex species also indirectly promotes the transmission of malaria if the use of bed nets or indoor residual spraying is discontinued due to a lack of insecticide efficacy against it. A recent survey revealed widespread occurrence of pyrethroid resistance among urban populations of this mosquito in Ghana. In order to plan and implement insecticide-based resistance management strategies, this study was carried out to assess resistance status of Culex species to organophosphate and carbamate in urban areas in Ghana and the possible mechanisms involved as well as environmental factors associated with its distribution. Methods: Mosquito larvae were sampled from various land use and ecological settings and in different seasons. In adults, susceptibility to organophosphates (fenitrothion, malathion) and carbamates (propoxur, bendiocarb) were determined. Mixed function oxidase (MFO) and alpha- and beta-esterase assays, as well as a PCR diagnostic assay to determine ace1 mutation were performed in individual mosquitoes. Results: Culex quinquefasciatus as well as C. decens and other unidentified Culex species were found breeding in polluted water bodies in the study sites. Across all sites and seasons, carbamate induced mortality was 94.1% +/- 15.4 whereas mortality caused by organophosphate was 99.5% +/- 2.2. In addition, ace1 mutation and high levels of esterases were detected in some of the mosquito populations. There was a strong correlation between susceptibility status of the mosquitoes and the level of absorbance of beta-esterase (Pearson r = -0.841, p = 0.004). Conclusions: The study found low prevalence of resistance to carbamate and organophosphate insecticides among Culex species from Ghana. However, there were populations with ace1 mutations and high levels of esterases, which can confer high resistance to these classes of insecticides. Thus, it is important to monitor activities or behaviour that has the potential to select for carbamate and organophosphate resistance populations

Limited Range of Genetic Variation in \u3ci\u3eEchinococcus multilocularis\u3c/i\u3e

DNA sequencing of 1.3 kb of rDNA containing both internal transcribed spacers (ITS1, ITS2) and adjoining rRNA coding regions in each of 11 Echinococcus multilocularis isolates from Germany, Japan, and Alaska resulted in identical nucleotide sequences except for a single polymorphic locus 54 bp upstream of the 3\u27 end of the 18S coding region, separating Eurasian isolates from an Alaskan isolate. The same base substitution was found in each of two additional isolates from Alaska. The distribution of the resulting genotypes with regard to their origin is highly significant (\u3e99.9%) and corresponds to the traditional subspecies Echinococcus multilocularis multilocularis and Echinococcus multilocularis sibiricensis

Value of histopathology, immunohistochemistry, and real-time polymerase chain reaction in the confirmatory diagnosis of Encephalitozoon cuniculi infection in rabbits

Morphological lesions in kidneys and brain are all too often considered diagnostic for confirmation of encephalitozoonosis in rabbits. The current study evaluated the diagnostic value of histology versus other etiological tests, including immunohistochemistry and real-time polymerase chain reaction (PCR) for Encephalitozoon cuniculi infection diagnosis. Samples of brain, heart, lungs, intestine, liver, and kidneys from 81 rabbits were examined for morphological lesions attributed to E. cuniculi infection as well as for the presence of spores and E. cuniculi antigen. Of these, 55 rabbits were tested for E. cuniculi DNA. Histological changes consistent with E. cuniculi infection were seen in 33 rabbits (41%, 33/81) representing 87% (33/38) of all rabbits with confirmed E. cuniculi infection. Brains of these rabbits displayed 6 different types of focal lesions corresponding to the stage of infection and specific tissue response. In 5 rabbits that were tested positive, histology was either inconclusive or inconspicuous. Etiological diagnosis was based on histological spore detection in 16% (6/38) of infected rabbits. Immunohistochemistry was more sensitive (42%, 16/38) than histological spore detection, and real-time PCR proved to be the most sensitive of all investigated methods (30/35, 86% of the examined rabbits with E. cuniculi infection). Encephalitozoon cuniculi infection rarely occurs without characteristic kidney and brain lesions. However, the spectrum of brain changes is wider than previously reported. Based on these findings, confirmation of pathogenic E. cuniculi infection should include standard histology of the predilection sites and a specific etiological assay, preferably real-time PCR

Zoonotic Potential of Enterocytozoon bieneusi

The reservoirs and the modes of transmission of the most frequent microsporidial species in humans, Enterocytozoon bieneusi, are still unknown. We have examined fecal samples of 26 humans and 350 animals from 37 species to find 18 samples containing this parasite from humans, cats, pigs, cattle, and a llama. Genotypic characterization of the internal transcribed spacer of the rRNA gene resulted in 14 different genotypes, 6 of them previously undescribed. Phylogenetic analysis revealed the lack of a transmission barrier between E. bieneusi from humans and animals (cats, pigs, and cattle). Thus, E. bieneusi appears to be a zoonotic pathogen

Baseline characteristics of patients, N = 326.

a<p>1 missing information.</p>b<p>2 missing informations.</p>c<p>One case without DST result for all 2^nd line drugs.</p>d<p>Exclusion of 15 patients with mixed or double infection.</p><p>E: ethambutol; S: streptomycin; H: isoniazid; MDR: multidrug resistance; XDR: extensively drug-resistance.</p