Parasite Epidemiology and Control最新文献

Background

Bed bugs are hematophagous insects with a long history of presence in human communities. Over the last three decades, infestations by bed bugs in human dwellings have drastically increased, leading to a rise in bed bug concerns. Nevertheless, very little is known about the bed bug species and their population diversity in Algeria.

Method

A pilot entomological inventory was performed in May 2019 in Tizi Ouzou, in northern Algeria. The gathered bed bug specimens were identified by morphological and molecular approaches, followed by neighbor-joining and network phylogenetic analyses.

Results

A total of seven out of 12 requested locations were allowed to inspect for bed bug infestation. Of these, three locations were found with active bed bug infestations. A total of 145 specimens belonging to different life stages [egg (21), nymph (74), adult male (17), and female (33)] were collected and analyzed using morphological and molecular approaches. The adult specimens were identified as Cimex lectularius according to specific morphological criteria, most importantly the pronotum laterally expanded with more flattened extreme margins. Morphological identification of the adults was confirmed further by conventional PCR targeting 450 bp fragment of the COI gene. All the nymphs and eggs were also molecularly identified as C. lectularius. Neighbor-Joining phylogenetic tree reconstructed with the collected specimens provides clues on the presence of two closely phylogenetic groups. The first one gathers our samples of Algeria with previously reported COI haplotype sequences from Asian, European, and North American countries. The second group encompasses a lesser-documented haplotype reported in Europe and Central America. These findings were further confirmed by network analysis.

Conclusions

These results provide evidence of established C. lectularius infestation in Algeria and its potential dispersal capacity by travelers or immigrants and will help future management of these ectoparasites.

Rodents may serve as reservoirs of zoonotic species of Cryptosporidium; however, data from molecular surveys in support of this hypothesis are still scarce. In this study, we screened faeces and rectal content from murid and cricetid rodents (N = 58) caught around three farms in Zealand, Denmark, for Cryptosporidium spp. by amplicon-based next-generation sequencing (NGS) of ribosomal genes. Selected samples were further examined using nested conventional PCR targeting SSU rRNA, gp60, and actin genes. Cryptosporidium-specific DNA was identified in 40/58 (69%) samples, and in 12 (30%) of the 40 positive animals, mixed cryptosporidial infections were observed. Cryptosporidium ditrichi was the species most commonly identified, found in 28 (48%) of the animals. Cryptosporidium parvum was identified in 4 (7%) of the animals, all of which were co-infected with C. ditrichi. The present study is the first to utilize NGS-based screening for Cryptosporidium species in wild rodents. Moreover, it is the first study to provide molecular data on Cryptosporidium in rodents sampled in Denmark and to detect DNA of C. ditrichi in Mus musculus, Myodes glareolus, and Microtus agrestis. The NGS approach was successfully applied to yield new knowledge, and the results showed that zoonotic species of Cryptosporidium are common in murid and cricetid rodents in Zealand, Denmark.

Monieziasis is a parasite-borne production-limiting disease of livestock. Moniezia expansa is the most important species having cosmopolitan distribution. Despite of numerous prevalence reports, very little information is available about the evolutionary biology and population genetics of M. expansa. To close this research gap, this study was undertaken to recognize and inspect the genetic variation of M. expansa populations around the world using the cox1 and nad1 genes and deduce phylogenetic relationships with M. expansa populations. The cox1 and nad1 gene sequences were downloaded from the NCBI GenBank database. Followed by sequence alignment, median-joining networks were constructed using PopArt software. Diversity and neutrality indices were computed through DnaSp software while MEGA software was used to draw the maximum-likelihood phylogenetic tree. Thirty-two cox1 sequences, from five different countries, and 9 nad1 sequences from three different countries, were among the sequences used in this study. The cox1 and nad1 gene sequences had mutations in 97 and 36 different places, respectively. Twenty and 7 unique haplotypes were discovered for the cox1 and nad1 gene sequences, respectively. Comparable haplotype diversities were observed for both the genes under study (cox1 = 0.950; nad1 = 0.944). Negative Tajima's D and Fu Fs were found for the cox1 gene while these indices were positive for the nad1 gene. Phylogenetic analysis also showed the existence of unique haplotypes for both the cox1 and nad1 genes. The results of this study indicate that there is the existence of a huge genetic diversity in M. expansa isolates. For future studies, it is recommended that longer gene sequences should be used to describe genetic variation among M. expansa isolates as the length of the gene under study affects the genetic variation. Moreover, additional mitochondrial markers should also be investigated because the assertive strength of a group of gene targets is superior to defining genetic diversity.

A free-roaming dog population remains one of the major public health problems in many developing countries. In this study, we investigated the potential impact of owned roaming and stray dogs on the persistence and possible eradication of Guinea worm disease (GWD) in Chad. We developed and analysed a multi-host of Guinea worm; and considered dogs as the definitive hosts, and fish as the intermediate hosts. Currently, GWD cases in the human population are low; hence, we ignored the human population in this study. We derived the reproduction number and explored how it depends on different model parameters that define it. We calibrated the proposed model with data from literature and validated it with recently reported GWD monthly data for dog infection in Chad from 2019 to 2022. Results show that detection and tethering of infectious owned free-roaming dogs combined with culling of stray dogs are effective disease management strategies. Hence, attainment of certain threshold levels for these interventions could lead to disease eradication. Overall, the study revealed how different factors could be applied to effectively manage GWD transmission in the dog population. Findings from this study could be used to support decision-making in GWD control strategies.

Mathematics Subject Classification (2010): 92B05, 93A30, 93C15.

Geohelminthiases are endemic in Chad and constitute a serious public health problem. This study aimed at determing the prevalence and risk factors of intestinal geohelminthiasis in children aged 5–15 years in the city of Moundou, Chad. This was a cross-sectional and descriptive study carried out in the city of Moundou. A total of 333 pupils participated in this study and it included children aged from 5 to 15 years attending three public primary schools in Moundou. A questionnaire was administered to each student after obtaining Informed Consent from either parent. Stool samples were collected in a sterile container and, the formalin-ethyl ether concentration technique was used to identify parasite. Parasitic load was assessed using the Mc Master cell method. The collected data were analyzed using Excel; Word 2016 and SPSS 20 software. An overall prevalence of 16.52% was obtained, 9.3% for Trichuris trichiura, 6.9% for Ascaris lumbricoides, and 1.2% for Hookworms. Male participants were more infected (67.24%) than females (32.76%). The age group]9–13] was the most infected (53.44%), followed by the age group [5–9](44.83%) and finally the age group]13–15] (1.73%). The Ouhoud school was the most infected (55.17%) followed by the Adoum Dallah school (39.66%) and finally the Centre school (5.17%). However, no statistically significant difference between gender and geohelminthiasis infection was recorded (p > 0.05). Regarding risk factors, statistical analysis showed that age group]9–13] (OR = 1.997 at 95% CI at [1.085–3.677]), Central Public School (OR = 1.55 at 95% CI at [0.63–2.46]), tap water (OR = 29 at 95% CI at [20.89–38.70]), not maintaining latrines (OR = 2.37 at 95% CI at [0.62–3.78]), and maintenance of latrines by pupils (OR = 1.5 at 95% CI at [0.63–2.46]) were risk factors. This study shows a high prevalence of geohelmenthiasis among children of three primary schools in Moundou, Chad. Although males were more infected than female there was no significant difference between gender and geohelminth infections (p = 0.114). was no gender difference. Identified risk factors of geohelmenthiasis infections among the study population were: age between 9 and 13 years, school water consumption, the use of unmaintained latrines and latrines maintained by students. Surveillance of geohelminthiases and hygiene should be intensified to reduce the pathological risk related to these parasites in Chad.

Foodborne diseases now represent one of the most important public health problems. The objectives were to analyze the leafy vegetables and crop soil to detect parasitic species and evaluate the factors that increase the risk of parasitic contamination in the productive units in La Plata horticultural area. The study included 261 leafy vegetable and 87 crop soil samples that were processed using washing, sedimentation, and flotation techniques. Socio-environmental characteristics and agricultural practices were surveyed, and a generalized linear model was used to assess the change in parasitic prevalence with different predictor variable. The 58.6% of leafy vegetable and 31.0% of crop soil samples contained parasitic species, the most prevalent being Blastocystis sp. and oocysts of Cryptosporidium spp. Risk factors were the limited access to health, dirt roads, children and dogs circulating in crops, field cultivation, furrow irrigation and lettuce cultivation. The high prevalence of intestinal parasites in the vegetable crops was mainly associated with the conditions of structural precariousness in the production units. These results elaborated with the participation of the population, provide valuable knowledge for the planning of epidemiological programs that include environmental health as a fundamental nexus in health campaigns.

This study aimed to develop maps for Fasciola hepatica infection occurrence in dairy cattle in the districts of Matahuasi and Baños in the Peruvian central highlands. For this, a model based on the correlation between environmental variables and the prevalence of infection was constructed. Flukefinder® coprological test were performed in samples from dairy cattle from 8 herds, during both the rainy and wet season. Grazing plots were geo-referenced to obtain information on environmental variables. Monthly temperature, monthly rainfall, elevation, slope, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), normalized difference water index (NDWI), distance to rivers, urban areas and roads were obtained by using remote sensor images and ArcGIS®. Multilayer perceptron Artificial Neural Networks modeling were applied to construct a predictive model for the occurrence of fasciolosis, based on the relationship between environmental variables and level of infection. Kappa coefficient (k > 0.6) was used to evaluate concordance between observed and forecasted risk by the model. Coprological results demonstrated an average prevalence from 20% to 100%, in Matahuasi, and between 0 and 87.5%, in Baños. A model with a high level of concordance between predicted and observed infection risk (k = 0.77) was obtained, having as major predicting variables: slope, NDWI, NDVI and EVI. Fasciolosis risk was categorized as low (p < 20%), medium (20% < p < 50%) and high (p ≥ 50%) level. Using ArcGIS 10.4.1, risk maps were developed for each risk level of fasciolosis. Maps of fasciolosis occurrence showed that 87.2% of Matahuasi area presented a high risk for bovine fasciolosis during the dry season, and 76.6% in the wet season. In contrast, 21.9% of Baños area had a high risk of infection during the dry season and 12.1% during the wet season. In conclusion, our model showed areas with high risk for fasciolosis occurrence in both districts during both dry and rainy periods. Slope, NDWI, NDVI and EVI were the major predictors for fasciolosis occurrence.

Schistosomiasis is a tropical disease that widely neglected. Schistosoma mansoni reproduce asexually within the freshwater snail, Biomphlaria alexandrina. Sodium hypochlorite (NaOCl) is a widely used disinfectant, so its effect against gainst B. alexandrina snails was evaluated. The present results showed that NaOCl has a molluscicidal activity against adult B. alexandrina snails at LC₅₀ 1.25 ppm. Hemocytes displayed varied morphological forms after being exposed to the LC10 and LC25 concentrations of NaOCl in B. alexandrina snails, and the phagocytic index of B. alexandrina snail's hemocytes significantly increased. The phagocytic potency of exposed hemocytes to charcoal showed ruptured plasma membrane, engulfed particles, vacuolation in the cytoplasm and degeneration of nuclei. When B. alexandrina snails were treated with sublethal concentrations of NaOCl, transaminases (AST & ALT), alkaline and acid phosphatase activities were significantly increased. In contrast, the total protein, albumin concentrations, Testosterone (T) and 17β Estradiol (E) showed a significant decrease (p ≤ 0.05) as compared to the control groups. The molecular docking interaction showed high efficiency for the ligand, NaOCl against the receptor binding sites of the acid phosphatase, alanine aminotransferase, estrogen and testosterone. The present results showed that NaOCl could be used as an effective molluscicide against B. alexandrina snails but more attention should be paid to investigate the side effects on the non-target organisms living in the freshwater environment.

By the end of 2022, the nationwide incidence of stunting remained high, including in Lampung Province, where it was 15.8%, above the target of 14% to be achieved by 2024. Since 2019, stunting has become a national priority due to suspected factors such as low nutrition intake, especially from animal protein sources, high rates of worm infections, and low compliance of under-fives in consuming deworming drugs. Therefore, this research aimed to analyze the relationship between deworming consumption, adequacy of animal protein intake, and stunting incidence in children aged 12–59 months in Bandar Lampung in 2022.

This research used an analytic survey with a cross-sectional approach to analyze the relationship between deworming consumption, adequacy of animal protein intake, and stunting in under-fives at two priority stunting handling neighbourhoods in Bandar Lampung, namely Way Gubak and Karang Maritim. The sample consisted of 262 under fives and their mothers who visited the integrated health post in the selected neighbourhoods from November to December 2022, and the data obtained were analyzed using logistic regression.

The results revealed a relationship between the consumption of an deworming and varying animal protein consumption with stunting incidence. This indicated a need to promote the importance of consuming deworming and adequate consumption of animal protein with variation to prevent stunting in children in Bandar Lampung.

Livestock, mainly goats, are crucial for animal protein, household income, economic security, and wealth creation in the pastoral areas of eastern Ethiopia. However, gastrointestinal parasitosis poses a substantial challenge in this sector. A cross-sectional study was conducted in the Gursum district of the Somali region, Ethiopia, to investigate the prevalence and intensity of gastrointestinal nematodes in goats and their associated risk factors. A total of 384 goat fecal samples were collected and examined using flotation and McMaster egg counting techniques for GIT nematodes. Coprological cultures have also been conducted for nematode identification. Fecal samples showed an overall parasite prevalence of 54.17%, with identified nematodes including Haemonchus (24%), Strongyloides (10.4%), Trichostrongles (6.5%), Nematodirus (6%), Oesophagostomum (5.5%) and Trichuris (1.87%). Older and poor body condition animals had higher chances of hosting nematodes than younger (OR = 0.245; CI = 0.144–0.417) and good body condition animals (OR = 0.069; CI = 0.030–0.157), according to multivariate logistic regression analysis. Quantitative examination of eggs revealed light 75(36.06%), moderate 99(47.60%), and heavy infection (n = 34, 16.35%). Analysis of the different study variables indicated that the age and body condition of the animals and the season of the year had a statistically significant association with the prevalence of GIT nematode infections (P-value <0.05). The high prevalence and intensity of GIT nematodiasis in goats from the study area warrants immediate attention and the implementation of strategic control and prevention measures.