Parasite Epidemiology and Control最新文献

Background

Worldwide, >654 million children live in regions where soil-transmitted helminth (STH) infections are endemic. These parasites cause a variety of symptoms, including anemia.

Methods

In May 2023, fecal and blood samples were collected from children aged 6 to 11 years attending government run (public) elementary schools in the Simanindo and Ronggur Nihuta sub-districts of Samosir Island, Indonesia where a twice a year mass drug administration (MDA) program is currently in place. A questionnaire was administered to students' parents or adult family members on possible risk factors for STH infections. Qualitative data were collected through in-depth interviews and focus group discussions.

Results

In total, 187 and 221 children in Simanindo and Ronggur Nihuta provided samples, respectively. The STH infection prevalence in Simanindo was 4.8% (9/187) and the infection prevalence in Ronggur Nihuta was 5.9% (13/221). In Simanindo, all infections were caused by Trichuris trichiura (n = 9), and in Ronggur Nihuta infections were caused by Ascaris lumbricoides (n = 6), Trichuris trichiura (n = 5), and A. lumbricoides + T. trichiura (n = 2). Three children had anemia but were negative for STH infections. While the results of the parent/adult questionnaires indicated access to a generally safe water supply and septic system, information from the in-depth interviews and focus groups revealed that the local water supply becomes greatly diminished during the dry season.

Conclusions

While MDA has been shown to effectively control roundworms and hookworms, additional measures to control trichuriasis are needed. There is also a need for the government to invest in improving the public water supply infrastructure.

Globally, Corona Virus Disease (COVID-19) has significantly affected communities in various aspects. The World Health Organization proposed different measures to prevent the pandemic. However, these measures in some instances have not effectively minimized the impacts of COVID-19, due to innumerable factors, inter alia, considerable “infodemic” related to myths, misinformation, and misconceptions. Knowledge of the “infodemic” on COVID -19 can lead to effective interventions to rid societies of COVID-19, hence reduction of COVID-19-related risks and outcomes. This article explores the “COVID-19 infodemic” that affected community responses to COVID-19 in Africa. The study employed a scoping review approach involving peer-reviewed articles from numerous search engines and databases. The keywords involved in the search query were: “COVID-19 infodemic, COVID-19 false news, COVID-19 in Africa, ‘knowledge of COVID-19, ‘myths, misinformation, and misconceptions on COVID-19, ‘history of COVID-19’, ‘community responses to COVID-19 in Africa”. Findings show that 5G technology transferred coronavirus, high temperature and alcohol can kill coronavirus, blacks are immune to COVID-19, COVID-19 vaccine development has been rushed hence not very effective and safe and also causes infertility. Diverse community responses have been registered which in some ways frustrated efforts in combating the pandemic. Therefore, the “infodemic” consisting of myths, misconceptions, and misinformation have been resulting from the history of COVID-19 which first affected white people more than blacks. Also, low knowledge of how the virus is transmitted and affect human being; and the notion that COVID-19 affects richer than poor people, hence since white people are richer than black people then they were the first to be affected by the pandemic. Obviously in presence of such myths, misconceptions, and misinformation; community responses in combating COVID-19 have not been very effective in Africa. For these interventions to be effective, collective efforts involving various stakeholders to raise awareness of COVID-19 are needed.

Background

Loiasis is an endemic filarial infection in the rainforest zone of West and Central Africa. Repeated annual community-directed treatment with ivermectin (CDTI) delivered for several years to control onchocerciasis has been shown to reduce the prevalence and intensity of Loiasis in some Loa loa-Onchocerca volvulus co-endemic areas. However, the impact of these multiple rounds of CDTI on entomological indicators of loiasis transmission is not known, and was therefore assessed in this study in areas with contrasting histories of CDTI.

Methods

The study was conducted in the East, North-west and South-west 1 CDTI project sites of Cameroon. Two communities per CDTI project were selected for fly collection and dissection. Ivermectin treatment coverage was documented in these areas, and this was correlated to Chrysops infection and infective rates. A total of 7029 female Chrysops were collected from 6 communities of the 3 CDTI projects (East, North-west, and South-west 1) and from 2 communities in a non-CDTI district (East).

Results

Chrysops biting densities and parous rates were significantly reduced in the North-west and South-west sites post-CDTI, while in the East, biting densities were similar in non-CDTI and CDTI sites, with higher parous rates observed in the non-CDTI site. Infection and infective rates in the East non-CDTI site were 4.4% and 1.8% respectively, as compared to 3.3% and 1.3% in the CDTI site after 10 ivermectin rounds (there were no baseline data for the latter). In the North-west site, significant reductions in Chrysops infection and infective rates from 10.2% and 4.2% respectively, to 3.5% and 1.2 (after 9 rounds of ivermectin treatment), were recorded following CDTI. In the South-west, infection rate significantly increased from 1.74% to 2.8% and infective rate remained statistically unchanged after 14 rounds of CDTI (0.45% - 0.40%). Similar trends in Mean Head L3 were observed except in the East site where this indicator was similar in both CDTI and control sites. Only in the North-west site did monthly transmission potentials decrease significantly.

Conclusion

This study demonstrated that the impact of repeated annual treatment with ivermectin for the control of onchocerciasis using community directed delivery approach on the entomological indicators of loiasis varies with bioecological zones. Community directed treatment with ivermectin induced a significant reduction in the entomological indicators of loiasis in the North-West project site which lies in forest savanna area. A non-significant decrease was observed in the East project site and in contrast, a significant increase was observed in the South-West 1 project site which both lies in the rainforest zones.

Dengue viruses are a significant global health concern, causing millions of infections annually and putting approximately half of the world's population at risk, as reported by the World Health Organization (WHO). Understanding the spatial and temporal patterns of dengue virus spread is crucial for effective prevention of future outbreaks. By investigating these patterns, targeted dengue surveillance and control measures can be improved, aiding in the management of outbreaks in dengue-affected regions. Curaçao, where dengue is endemic, has experienced frequent outbreaks over the past 25 years. To examine the spatial and temporal trends of dengue outbreaks in Curaçao, this study employs an interdisciplinary and multi-method approach. Data on >6500 cases of dengue infections in Curaçao between the years 1995 and 2016 were used. Temporal and spatial statistics were applied. The Moran's I index identified the presence of spatial autocorrelation for incident locations, allowing us to reject the null hypothesis of spatial randomness. The majority of cases were recorded in highly populated areas and a relationship was observed between population density and dengue cases. Temporal analysis demonstrated that cases mostly occurred from October to January, during the rainy season. Lower average temperatures, higher precipitation and a lower sea surface temperature appear to be related to an increase in dengue cases. This effect has a direct link to La Niña episodes, which is the cooling phase of El Niño Southern Oscillation. The spatial and temporal analyses conducted in this study are fundamental to understanding the timing and locations of outbreaks, and ultimately improving dengue outbreak management.

Background

Pediatric schistosomiasis has been recognized as a public health concern in schistosomiasis endemic areas of sub-Saharan Africa, including Tanzania. However, there is limited epidemiological information relating to pediatric schistosomiasis in Tanzania. Therefore, this current focused on assessing the geographical prevalence of S. mansoni infection and its associated risk factors in pre-school children (PreSAC) in southern and north-western Tanzania.

Methods

A total of 1585 PreSAC aged 1–6 years were enrolled in a cross-sectional study. A single urine and stool sample were obtained from each child and processed using point-of-care circulating cathodic (POC-CCA) antigen and Kato Katz (KK) technique. The overall prevalence of S. mansoni infection based on KK technique and POC-CCA test were 18.6% (95%CI:16.7–20.6) and 28.3% (95%CI:26.1–30.6), respectively. The overall geometrical mean eggs per gram of faeces was 110.38epg (95% CI:97.3–125.3). The age group 4–6 years had the highest prevalence (P < 0.01) of S. mansoni in both diagnostic tests and infection intensity (t = −2.8398, P < 0.005) using KK technique. On multivariable analysis, only Ukerewe district was associated with S. mansoni infection based on KK technique (aOR = 2.8 (95%CI:2.1–3.9), P < 0.001). Based on POC-CCA test, age group (4–6 years), aOR = 1.7, 95%CI:1.3–2.2, P < 0.001), Nyasa (aOR = 6.2, 95%CI:3.0–12.5, P < 0.001), Geita (aOR = 4.2, 95%CI:2.1–8.2, P < 0.001) and Ukerewe (aOR = 28.9, 95%CI:15.0–55.8, P < 0.001) districts remained independently associated with S. mansoni infection.

Conclusion

Schistosoma mansoni is a public health concern among PreSAC in the study districts and its prevalence varies from one geographical setting to another. These findings strongly support the need to include pre-school aged in preventive chemotherapy.

Background

Asymptomatic malaria during pregnancy is a significant public health concern in malaria-endemic regions, which worsens the various effects of malaria on the mother and fetus and increases maternal and neonatal mortality. To date, no meta-analysis has been conducted on asymptomatic malaria in pregnant women in Ethiopia. Thus, we aimed to estimate the pooled prevalence of asymptomatic malaria and its associated factors in pregnant women in Ethiopia.

Methods

PubMed/Medline, Google Scholar, Web of Science, Cochrane, AJOL, and Ethiopian University repositories were systematically searched to identify studies reporting the prevalence of asymptomatic malaria infection among pregnant women in Ethiopia. A random effects model was used to perform the analysis. The heterogeneity of the studies was assessed with the I-squared tests, and subgroup analyses were performed to identify the sources of heterogeneity.

Results

Ten articles with 3277 study participants were included in this review. The pooled prevalence of asymptomatic malaria infection among pregnant women in Ethiopia was 7.03% (95% CI: 6.23–9.12); I² = 81.2%). In the species-specific pooled prevalence estimate, Plasmodium falciparum prevalence was 5.34% (95%CI: 3.38–7.3; I2 = 87.8%), and Plasmodium vivax prevalence was 1.69% (95%CI: 1.2–5; I2 = 91.5%).Not using insecticide-treated bed nets [OR = 7.36, 95% CI (2.75, 19.73)], being primi-gravida [OR = 1.86, 95% CI (1.23, 2.82)]; lack of health education about malaria prevention [OR = 6.86, 95% CI (2.90, 11.44)] were predictors of asymptomatic malaria infection during pregnancy.

Conclusion

This study revealed that asymptomatic malaria was prevalent among pregnant women in Ethiopia. This suggests that relying merely on reported symptoms may result in missed malaria cases. Therefore, regular screening and treatment protocols for malaria are recommended in antenatal care. It is also crucial to ensure that pregnant women have access to insecticide-treated bed nets and other effective malaria prevention measures.

Tick-borne diseases have a major adverse effect on livestock worldwide, causing enormous economic losses in meat and milk production as well threatening animal and public health. In this study, we aimed to detect and characterize piroplasms isolated from cattle and buffalo in southern Egypt, using molecular techniques. Three hundred blood samples were collected from cattle and buffalo in two governorates in southern Egypt. All 300 samples (100%) were confirmed to contain DNA, as they exhibited bands of bovine β-actin gene at the expected 227 bp for cattle and buffalo. The samples were analyzed by PCR for the presence of piroplasms, specifically Babesia bovis, Babesia bigemina, and Theileria annulata. Samples positive for the piroplasma 18S ribosomal RNA gene were further examined for two additional genes, spherical body protein 4 gene, to provide an enhanced degree of specificity for the identification of B. bovis and B. bigemina, and the major merozoite surface antigen gene for T. annulata. The infection rate for piroplasma spp. was 60/300 (20%). The positivity rates were 10.7% (32/300) for T. annulata, 5.3% (16/300) for B. bovis, and 4% (12/300) for B. bigemina. By host species, 42/150 (28%) cattle and 18/150 (12%) buffalo were positive for piroplasms. None of the isolates sequenced for the B. bovis isolates from buffalo in this study showed 100% identity with any sequence deposited in GenBank for the small subunit ribosomal RNA gene (maximum identity value = 99.74%). Similarly, no T. annulata small subunit ribosomal RNA gene sequence identified in this study exhibited 100% identity with any sequence deposited in GenBank (maximum identity value = 99.89%). The current study provides a partial sequence of the T. annulata merozoite-piroplasm surface antigen gene, as well as the B. bovis and B. bigemina spherical body protein 4 genes, in cattle and buffalo in southern Egypt, and is the first report on these piroplasma genes in cattle and buffalo in southern Egypt.

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.