Parasite Epidemiology and Control最新文献

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.

Little information is available on the epidemiology of varroosis caused by Varroa mite, Varroa destructor infestation in Ethiopia, although it is a devastating honeybee disease that results in significant economic losses in beekeeping. Therefore, between October 2021 and October 2022, a cross-sectional study was carried out in different agroecology zones in Southwest Ethiopia to determine the prevalence and associated risk factors for varroosis, as well as the effects of this disease on honeybee colonies and honey production. A multivariate logistic regression analysis was performed to identify possible risk factors for the prevalence of V. destructor. A total of 384 adult honeybee and worker or drone brood samples were collected from honeybee colonies and examined using standard diagnostic techniques in the laboratory. The result shows that the prevalence of V. destructor was found to be 39.3% (95% CI 34.44–44.21) and 43.2% (38.27–48.18) in adult honeybees and brood, respectively. The major risk factors for the prevalence of V. destructor in the study areas included agroecology (OR = 5.2, 95% CI 1.75–14.85), type of hive (OR = 2.9, 95% CI 1.17–17.03), management system (OR = 4.3, 95% CI 1.23–14.70), and colony management (OR = 3.5, 95% CI 1.31–9.14). The lower level of colony infestation in adult bees and brood was measured as 1.97 ± 0.14 and 3.19 ± 0.25, respectively. Season, colony status, colony management, and agroecology were among the determinant factors of the level of varroa mite infestation in adult bees and brood. The results of the study demonstrated that honey production losses are largely attributable to V. destructor infestation. Therefore, it is critical to inform the community about the effects of V. destructor on honey production and develop and implement effective management strategies for this disease. In addition, further research should be done to identify and isolate additional factors that contribute to varroosis in honeybees in different regions.

Background

World Health Organization (WHO) recommends periodic praziquantel Mass Drug Administration (MDA) to vulnerable populations, especially school-aged children, to reduce the risk of transmission. In the S. haematobium endemic Lindi region, on the southeastern coast of Tanzania, praziquantel has been distributed for more than a decade (12 rounds) in schools. However, there is a paucity of data on the current burden and factors perpetuating ongoing urogenital schistosomiasis among SAC. The study investigated the prevalence and factors associated with the ongoing transmission of S. haematobium among school-age children (SAC) after 12 rounds of praziquantel in Nachingwea, Southern Tanzania.

Material and methods

A quantitative cross-sectional study was conducted between May and June 2022 among 483 SAC in the Nachingwea district. Macrohematuria, microhaematuria, and S. haematobium eggs were assessed in the collected urine sample for each participant, using macroscopic observation, urine dipstick, and urine filtration techniques, respectively. Infection intensity was quantified for positive S. haematobium urine samples. Knowledge and attitudes towards schistosomiasis were assessed among participants through an interview-administered questionnaire, and water contact practices were registered through an observation checklist. Data were summarized using descriptive statistics, the Chi-square test, and logistic regression.

Results

The prevalence of S. haematobium infection was 10.6%, with 0.6% (3/51) prevalence of heavy infection. The factors associated with S. haematobium persistence transmission were a habit of visiting the water bodies (AOR = 1.62, 95% CI: 0.40–1.96), swimming in the visited water bodies (AOR = 4.58, 95% CI: 1.72–12.19), using water from the river source (AOR = 3.79, 95% CI: 1.51–9.51) and attending Mkumba Primary School (17.4%; AOR = 6.12, 95% CI: 1.64–22.85).

Conclusions

Findings suggest ongoing transmission of urogenital schistosomiasis in the Nachingwea District despite 12 rounds of praziquantel treatment, with a low prevalence of heavy infection (0.6%). Praziquantel distribution should be complemented with health education, especially on the cause and transmission of urogenital schistosomiasis to increase knowledge that will improve a good attitude towards schistosomiasis prevention. An adequate water supply is to be considered to reduce infections due to the visit to water sources for daily use.

The tick-borne encephalitis virus (TBEV) is a zoonotic agent that causes severe encephalitis in humans and is transmitted through the bites of infected ticks. Ixodes ticks are the primary vector for TBEV in Mongolia, and approximately 3.4% carry the TBEV. The ticks are capable of not only transmitting these viruses but also serve as excellent reservoir hosts. The Dermacenter tick species may have similar properties. TBEV is a significant cause of virus-related diseases of the central nervous system in many European countries as well as in China, Russia, and Mongolia. Our objectives were to investigate TBEV seroprevalence and infection risk factors in different biogeographical zones and provinces, especially in the highly endemic areas of Mongolia. Serum samples were collected from individuals who experienced tick bites (n = 993) in Mongolia between 2016 and 2022. Enzyme-linked immunosorbent assay of the samples was performed to evaluate for TBEV-specific immunoglobulin (Ig)M and IgG. We analyzed the risk factors and seroprevalence of TBEV infection among these individuals using a cross-sectional, questionnaire-based study. Statistical analyses were performed using a multistage cluster sampling survey design, and all data were analyzed using the R software. TBEV IgM and IgG antibodies were detected in 8.1% (80/993) and 20.2% (201/993) of all serum samples, respectively. The seroprevalence was significantly higher in men (68%, 95% confidence interval [CI]: 1.63–3.13, odds ratio [OR]: 2.25) than in women (p < 0.001). Additionally, the seroprevalence was significantly higher among unemployed (35.0%, 95% CI: 0.31–0.84, OR: 0.51) than employed individuals (p < 0.001). The seroprevalence was the highest among the 25–29 and 35–39-year age groups (11%, 95% CI: 1.29–5.51, OR: 2.65 and 11%, 95% CI: 0.94–3.87, OR: 1.9, respectively), and the lowest in the 65–69-year age group (4%, 95% CI: 0.46–6.15, OR: 1.83) (p < 0.001). Furthermore, the seroprevalence was the highest in Selenge province and the capital city Ulaanbaatar (40%, 95% CI: 1.73–21.7, OR: 5.07 and 28%, 95% CI: 0.51–6.89, OR: 1.57, respectively) and the lowest in Bayan-Ulgii and Dornod provinces (0.5%, 95% CI: 0.06–12.4, OR: 1.33 and 0.5%, 95% CI: 0.03–6.24, OR: 0.72, respectively). TBEV infection incidence remained low in most regions of Mongolia but increased in endemic areas. Furthermore, in the univariate subgroup analysis, age, occupation status, and residential area were significantly associated with TBEV seroprevalence.