Parasite Epidemiology and Control最新文献

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.

Introduction

Although house flies (Musca domestica) do not directly cause disease in humans, they transmit pathogens to them, which provide the basis for many diseases. The main way to deal with this insect is to use insecticides. Due to the resistance from insecticides, the fight against house flies has been hampered. This study aimed to determine the prevalence of knockdown resistance against organochlorine insecticides in house flies worldwide.

Methods

This study was conducted via a systematic review and meta-analysis to investigate the prevalence of knockdown resistance against organochlorine insecticides in house flies. Accordingly, by searching the databases of Web of Science, PubMed, Scopus, Proquest, Bioone, and Embase, all published articles were extracted, and reviewed until the end of May 2022. Statistical data analysis was performed using the random-effects model in the meta-analysis, meta-regression, and I² index.

Results

Nine studies entered the meta-analysis process. Based on this, the prevalence of knockdown resistance against organochlorine insecticide in house flies was estimated to be 49.1%. Meta-regression showed that the prevalence of knockdown resistance increased with increasing years of study but decreased with increasing sample size.

Conclusion

According to the findings, about 50% of house flies have knockdown resistance against organochlorine insecticide. As a result, it is necessary to adopt effective and combined methods to combat this insect to control it and prevent the transmission of diseases caused by it.

Background

Human cystic echinococcosis, as an emerging neglected parasitic disease, is caused by tapeworms of the genus Echinococcus spp. Because of the medical and economic importance, this study aims to review the epidemiology and clinical features of hydatidosis in patients admitted to medical and surgical wards in three referral teaching hospitals over 15 years in Mazandaran Province, northern Iran.

Methods

Data were collected from hospital records that were accessible via the hospital information system (HIS) between 2005 and 2019 (15 years).The demographic information (age, sex, living area, and occupation), dog contact, number of the cysts, types of organs involved, and history of disease recurrence were assessed.

Results

One hundred twenty-one patients with human cystic echinococcosis (CE) were involved in the study, from whom 58 patients (47.93%) were male and 63 (52.07%) were female. The majority of patients were rural residents (64.46%) and also housewife (28.10%). Based on the results, only about 16.53% of the patients had history of close contacts with dogs. The liver was the organ involved in the most cases of CE. There were statistically significant differences between residence, occupation, history of close contacts with dogs, type of organs involved, number of cysts and history of disease recurrence (P < 0.05).

Conclusions

Our data provides valuable registry-based information about CE in an endemic region. The data highlights that most patients lived in rural areas and were housewives. Additionally, they had a low rate of disease recurrence but a high rate of close contact with dogs. Moreover, further monitoring on registry-based program and strengthening the HIS in the provincial hospitals in the studied area are required.

Schistosomiasis is an aquatic snail borne parasitic disease, with intestinal schistosomiasis (IS) and urogenital schistosomiasis (UGS) caused by Schistosoma mansoni and S. haematobium infections, respectively. School-aged-children (SAC) are a known vulnerable group and can also suffer from co-infections. Along the shoreline of Lake Malawi a newly emerging outbreak of IS is occurring with increasing UGS co-infection rates. Age-prevalence (co)infection profiles are not fully understood. To shed light on these (co)infection trends by Schistosoma species and by age of child, we conducted a secondary data analysis of primary epidemiological data collected from SAC in Mangochi District, Lake Malawi, as published previously. Available diagnostic data by child, were converted into binary response infection profiles for 520 children, aged 6–15, across 12 sampled schools. Generalised additive models were then fitted to mono- and dual-infections. These were used to identify consistent population trends, finding the prevalence of IS significantly increased [p = 8.45e-4] up to 11 years of age then decreasing thereafter. A similar age-prevalence association was observed for co-infection [p = 7.81e-3]. By contrast, no clear age-infection pattern for UGS was found [p = 0.114]. Peak prevalence of Schistosoma infection typically occurs around adolescence; however, in this newly established IS outbreak with rising prevalence of UGS co-infections, the peak appears to occur earlier, around the age of 11 years. As the outbreak of IS fulminates, further temporal analysis of the age-relationship with Schistosoma infection is justified. This should refer to age-prevalence models which could better reveal newly emerging transmission trends and Schistosoma species dynamics. Dynamical modelling of infections, alongside malacological niche mapping, should be considered to guide future primary data collection and intervention programmes.

Background

Ticks cause substantial losses in cattle production, in terms of diseases, and reduced productivity, and are economically the most important ectoparasites of cattle.

Methods

A cross-section study was conducted from January 2022 to August 2022 in the Bedele district to identify genera and species of Ixodid ticks infesting cattle and determine the prevalence concerning host-related factors. Adult ixodid ticks were collected from 384 randomly selected cattle by using forceps and preserved in separate collecting bottles with 70% ethyl alcohol. The collected ticks were identified under stereomicroscope into species based on their morphology.

Results

Out of the 384 cattle examined, 276 (71.9%) were found with being infested by one or more tick species. A total of 3192 ticks were collected and identified. Three genera; namely Amblyomma, Boophilus and Rhipicephalus, and four species (Amb. cohaerence, Boophilus decoloratus, Amb. variegatem, and Rhip. evertsi evertsi) were identified with a prevalence rate of 44.8%, 26.8%, 14.1%, and 14% respectively. The respective prevalence for assessed risk factors was: 71.32%, 68.75%, 74.72%, 72.72%, 82.02%, 68.81%, 72.97%, 69.19%, 75.25%, 72.25%, 71.34%, 72.93%, 67.65%, 75.00% Bedele Town, Haro, Ilike Kararo, Obolo Bachara, Cross Breed, Local Breed, Young, Adult, Old, Male, Female, Poor, Medium, and Good, respectively. Only the association between the breed of cattle is statistically significant in terms of the prevalence of ticks (p < 0.05), and others risk factors (Kebele, age, sex, and body condition) were statistically insignificant (p > 0.05). Tick species were highly distributed on the udder part with a prevalence of (26.3%) and least in the vulva body region of the cattle (2.3%).

Conclusions

The present study indicated there is a high prevalence of ixodid tick infestation, especially in local cattle breeds, adults, males, poor body condition, and Bedele town. In line with this, further studies on factors affecting tick burden and tick control strategies are recommended.

Background

The surge in malaria cases and deaths in recent years, particularly in Africa, despite the widespread implementation of malaria-control measures could be due to inefficiencies in malaria control and prevention measures in malaria-endemic communities. In this context, this study provides the malaria situation report among children in three Municipalities in Northern Ghana, where Seasonal Malaria Chemotherapy (SMC) is implemented by Ghana Health Service (GHS).

Methods

A cross-sectional household survey was carried out to assess the malaria knowledge, attitudes, and practices (KAP) and malaria prevalence in 394 households in 13 rural communities in the Kumbugu, Nanton and Tolon Municipalities, Northern Region, Ghana. This was followed by screening for P. falciparum infection with anti-HRP2 RDT and PCR among children 1–17 years in the households. Plasma levels of IgG specific for crude P. falciparum antigen (3D7) and four recombinant malaria antigens (CSP, GLURP, MSP3, and Pfs230) were assessed by ELISA. The malaria and parasitaemia data were converted into frequency and subgroup proportions and disaggregated by study sites and demographic information of the participants. The ELISA data was converted to arbitrary units (AU) and similarly compared across study sites and demographic information.

Results

The P. falciparum infection rate and frequency of malaria were high in the study areas with significant age-dependent and inter-community differences, which were reflected by differences in plasma levels of P. falciparum-specific IgG. Over 60% of households reported the use of bed nets and indoor insecticide sprays/coils, and 14% mentioned bush clearing around homes (14%) as malaria preventive measures. Community health centres were the preferred place for households (88%) to seek malaria treatment but over-the-counter drug stores were the major source (66%) of their antimalarials. Overall, malaria preventive and treatment practices were sub-optimal.

Conclusions

P. falciparum infection and malaria are still high in the studied communities, indicating that preventive and control measures against the disease in the region remain inadequate. Efforts to ensure high SMC compliance and to improve preventative and treatment practices thus seem cost-beneficial “low-hanging fruits” in the fight against malaria in the Northern Region of Ghana.

Parasite aggregation within hosts is a fundamental feature of parasite distributions, whereby the majority of parasites are harboured by a minority of hosts. Parasite aggregation can influence their transmission and hence control. In this narrative review, possible sources of aggregation of Taenia solium cysticerci in pigs are discussed, along with implications for control of the parasite. While heavy T. solium infections in pigs could most likely be associated with ingestion of high doses of infective parasite eggs, consistent with coprophagic behaviour of pigs, lighter infections indicate a role of indirect routes of transmission to pigs, mostly from lower infection doses. Light infections are likely to be missed by commonly used diagnostic methods - tongue examination or meat inspection - and end up in the food chain. Hence, they entail a ‘hidden’ risk and are of a particular public health concern, especially in areas where meat is consumed raw or undercooked. To be effective and sustainable, control strategies against T. solium likely require a broader understanding of, and consideration for parasite transmission dynamics. More importantly, a holistic One Health approach incorporating interventions on humans, pigs and the environment will likely have a larger, more successful and sustainable impact.

Background

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, an obligate intracellular protozoan responsible for one of the most common congenital infections in the world. This study aimed to determine the seroprevalence and risk factors associated with toxoplasmosis in pregnant women consulted in three health centers in the city of Dschang.

Methods

This study was a cross-sectional study that was conducted, with a total of 242 participants. A questionnaire was administered after obtaining the free and informed consent of the participants. Blood sample was collected to assay IgG and IgM antibodies specific to Toxoplasma gondii using the enzyme-linked immunosorbent assay (ELISA) kit, and potential risk factors were evaluated with the administration questionnaire using a binary logistic regression model. Statistical significance was measured at P < 0.05.

Results

The overall seroprevalence of toxoplasmosis was 82.7%,with a seroprevalence of toxoplasma IgG of 62.8% (152), that of IgM at 11.6% (28) and that of IgG/IgM at 8.3% (20). The Saint Vincent Paul Hospital had a seroprevalence of 43.8% IgG and 8.7% IgM; followed by the Dschang District Hospital (11.6% IgG and 2.1% IgM). The seroprevalence of toxoplasma IgG (35.5%) and IgM (6.2%) was higher in multiparous pregnant women, and in the group of women who performed their first toxoplasmosis serology in the first trimester of pregnancy, 70 (28.9%), 9 (3.7%) respectively for IgG and IgM. The multivariate logistic regression analysis showed that the possession of a cat at home or its presence in the neighborhood, the consumption of undercooked or uncooked meat and having a history of blood transfusion were found to be statistically significant risk factors associated with toxoplasmosis seroprevalence among pregnant women.

Conclusion

The present study revealed a high seroprevalence of toxoplasmosis. Given this high seroprevalence, screening for toxoplasmosis in women of childbearing age should be encouraged.

Ivermectin has emerged as a therapeutic option for various parasitic diseases, including strongyloidiasis, scabies, lice infestations, gnathostomiasis, and myiasis. This study comprehensively reviews the evidence-based indications for ivermectin in treating parasitic diseases, considering the unique context and challenges in Peru. Fourteen studies were selected from a systematic search of scientific evidence on ivermectin in PubMed, from 2010 to July 2022. The optimal dosage of ivermectin for treating onchocerciasis, strongyloidiasis, and enterobiasis ranges from 150 to 200 μg/kg, while lymphatic filariasis requires a higher dose of 400 μg/kg (Brown et al., 2000). However, increased dosages have been associated with a higher incidence of ocular adverse events. Scientific evidence shows that ivermectin can be safely and effectively administered to children weighing less than 15 kg. Systematic reviews and meta-analyses provide strong support for the efficacy and safety of ivermectin in combating parasitic infections. Ivermectin has proven to be an effective treatment for various parasitic diseases, including intestinal parasites, ectoparasites, filariasis, and onchocerciasis. Dosages ranging from 200 μg/kg to 400 μg/kg are generally safe, with adjustments made according to the specific pathology, patient age, and weight/height. Given Peru's prevailing social and environmental conditions, the high burden of intestinal parasites and ectoparasites in the country underscores the importance of ivermectin in addressing these health challenges.