Parasite最新文献

Gastrointestinal infections caused by protozoan parasites remain a significant public health concern worldwide, particularly during the health crisis caused by the COVID-19 pandemic, which led to severe economic and social crisis that highlighted the inadequacy of healthcare services in many countries. In this study, we analyzed changes in the incidence of cases of amebiasis, giardiasis, and other gastrointestinal protozoal infections before (2017-2019) and during (2020-2022) the pandemic. Our findings indicate a decrease in the incidence of these infections, with no significant variations in incidence by gender or age, and a higher incidence during months with elevated temperature and humidity. Sociodemographic factors, including residence in homes with earthen floors, poverty, limited access to healthcare services, inadequate nutrition, unemployment, and overcrowded living conditions, were associated with an increased risk of infection. Additionally, our results highlight the impact of public health policies on disease control, demonstrating that COVID-19 containment measures - such as international travel restrictions, workplace closures, event cancellations, stay-at-home mandates, and enhanced hand hygiene - also contributed to reducing parasitic infections. The persistent prevalence of protozoal infections in both periods underscores the urgent need to improve sanitation, personal hygiene, and public health education, particularly in developing countries, to mitigate their high burden.

The nematode Nematodirus oiratianus is associated with major economic losses in the livestock industry, as it is a common gastrointestinal parasites of cattle, sheep, and other ruminants. These parasites primarily obtain nutrients by consuming the blood of their host. This study aimed to investigate changes in the intestinal microbiota of lambs infected with N. oiratianus before and after infection, using 16S rDNA sequencing technology. We aimed to reveal the impact of N. oiratianus infection on lamb intestinal microecology and to provide scientific evidence for the prevention and control of related diseases. Compared with the infected group, the control group had more bacterial species. Chao, Ace, and Shannon indices were significantly lower in the infected group (p < 0.05), while the Simpson index showed no significant difference (p > 0.05). These findings collectively indicate significant divergence in the composition of bacterial taxa between the infected and control groups. The phylum with the highest relative abundance in both groups was Firmicutes, followed by Bacteroidetes. Linear Discriminant Analysis Effect Size (LEfSe) identified significantly enriched taxa, including Proteobacteria, Bacteroides, and Campylobacteria in the control group, and Clostridiales, Firmicutes, and Ruminococcaceae in the infected group. Functional predictions indicated that the altered microbiota was associated with metabolic pathways such as carbohydrate, amino acid, and vitamin metabolism. Infection with N. oiratianus led to significant alterations in the diversity and composition of the intestinal microbiota in lambs.

The invasive hornet Vespa velutina Lepeletier, which first invaded South Korea in 2003, has spread throughout the country, significantly affecting apiaries, ecosystems, and human health. Xenos spp. (Xenidae, Strepsiptera) are primarily parasitic to social wasps, with V. analis being the only known host in Korea. Until recently, no parasites or parasitoids on V. velutina had been discovered. In 2020, strepsipteran parasites were discovered on 11 hornet workers in Andong City, South Korea. These parasites, comprising four larvae and seven pupae, were all male, except for one individual of an undetermined sex. Molecular analysis and morphological examination identified the parasites as Xenos moutoni (du Buysson, 1903) and X. oxyodontes Nakase & Kato, 2013. This marks the first recorded instance of strepsipteran parasites on V. velutina in regions invaded by this hornet. Although the exact infection rate of these parasites could not be determined, it appears that native strepsipteran parasites have adapted to a non-native Vespa species. Stylopization, the condition caused by these parasites, is known to negatively affect hornet colonies: infected workers do not contribute to nest activities, hindering nest development, and infected reproductive individuals (males and new queens) do not mate, which impedes the establishment of new colonies. However, due to the hornet's high reproductive rate and compensatory mechanisms, the overall control effect of the parasites is likely to be minor.

The Milu deer, or Père David's deer (Elaphurus davidianus), a rare endemic species in China, represents a case of successful reintroduction of a species previously considered extinct in the wild. Trichomonads, protozoan symbionts capable of infecting vertebrates, are transmitted via the fecal-oral route; they are a subgroup of Parabasalia and include some pathogenic species that pose zoonotic risks. Until now, data on the diversity and prevalence of trichomonads in Chinese Milu deer have not been reported. To better understand the colonization status of trichomonads, fecal samples from 112 Milu deer across five nature reserves in China were collected. The ITS-1/5.8S/ITS-2 sequences were amplified using PCR to investigate the colonization rate of trichomonads and to assess evolutionary relationships and genetic characteristics through phylogenetic analysis. An occurrence of 38.39% was recorded in Milu deer, with sample collection sites (OR = 55.159, 95% CI = 3.166-961.113, p = 0.006), high relative humidity and average annual rainfall (OR = 11.675, 95% CI = 1.747-77.781, p = 0.011) identified as significant risk factors for trichomonads colonization. Undescribed trichomonads from four genera were identified, including Simplicimonas spp., Hypotrichomonas spp., Hexamastix spp., and Tetratrichomonas spp. To our knowledge, this is the first study to report on trichomonads in Milu deer in China. This study aims to enhance understanding of trichomonad colonization and associated risk factors, providing scientific guidance for the ex-situ conservation of Milu deer.

Cryptosporidiosis, caused by a Cryptosporidium infection, is a serious gastrointestinal disease commonly leading to diarrhea in humans. This disease poses a particular threat to infants, young children, and those with weakened immune systems. The treatment of cryptosporidiosis is challenging due to the current lack of an effective treatment or vaccine. Ongoing research is focused on understanding the molecular pathogenesis of Cryptosporidium and developing pharmacological treatments. In this review, we examine the signaling pathways activated by Cryptosporidium infection within the host and their role in protecting host epithelial cells. Additionally, we also review the research progress of chemotherapeutic targets against cryptosporidia-specific enzymes and anti-Cryptosporidium drugs (including Chinese and Western medicinal drugs), aiming at the development of more effective treatments for cryptosporidiosis.

Amblyomma maculatum, the Gulf Coast tick, is a species of significant veterinary and public health importance, especially because it is a vector of important diseases, such as American canine hepatozoonosis and tidewater spotted fever. Amblyomma maculatum infests a wide range of vertebrates including livestock, dogs, cats, and humans. Two experimental studies were conducted to evaluate the efficacy of afoxolaner formulated in an oral tablet (NexGard^®) against induced infestations of A. maculatum in dogs. These Good Clinical Practice (GCP) studies used a randomized, negative controlled and masked design. In each study, 10 dogs were allocated to an untreated group and 10 dogs to a treated group, dosed once on Day 0 with a combination of tablets targeting the minimum therapeutic dose (2.5 mg/kg afoxolaner). Dogs were infested with 50 unfed adult A. maculatum on Days -2, 7, 14, 21, 28, and 35 (Study #1), or on Days -1, 14, and 28 (Study #2). Seventy-two (72) hours after treatment and subsequent infestations, ticks were removed and the numbers of live ticks in each group were used for efficacy calculations. At each time-point, all untreated dogs were adequately infested (i.e., with more than 12 live ticks), demonstrating a vigorous tick population and an adequate study model. The curative efficacy against established infestations, 72 hours after treatment, was 100% in Study #1 and 99.5% in Study #2. The preventive efficacy, 72 hours after the post-treatment infestations, ranged from 94.6% to 98.9% for five weeks in Study #1, and was ≥98.8% for four weeks in Study #2.

The introduction of non-native pet-traded species poses potential threats to global biodiversity, particularly in freshwater ecosystems. This study investigated the seasonal dynamics of microsporidian infections in an established feral population of cherry shrimp (Neocaridina davidi) and the coexisting populations of crustaceans, comprising both native and non-native species, inhabiting the thermal waters of the Fontcaude Park and the nearby Mosson River in southern France. Our aim was to assess the potential occurrence of spillover and/or spillback events between N. davidi and co-occurring crustaceans, as well as the influence of seasonal dynamics on these interactions. The prevalence and diversity of microsporidian parasites exhibited strong seasonal variations. Although parasites associated with the pet trade were not detected, we highlight the acquisition of native parasites by feral N. davidi, which seems to be a suitable alternative host for native host-generalist microsporidians. Our findings indicate that all prerogatives for spillback events to occur are met. Feral N. davidi may establish and survive year-round in European rivers with natural thermal regimes. Thus, human-mediated introductions can potentially alter parasite transmission dynamics in these ecosystems.

Babesia ovis is a tick-transmitted intraerythrocytic apicomplexan parasite that causes ovine babesiosis, a disease with high economic impact in endemic regions. Although Rhipicephalus bursa is a known biological vector of B. ovis, the dynamics of vertical (transovarial) transmission are poorly understood. In the present study, the transovarial transmission of B. ovis was investigated experimentally in four continuous generations of R. bursa under laboratory controlled conditions. A total of 11 sheep were used during the study. An initial stabilate co-infected with B. ovis and Theileria ovis was inoculated into a splenectomized sheep, followed by an infestation with Babesia-free adult R. bursa. Study of dead tick bodies and larval pools by molecular methodology confirmed the elimination of T. ovis and the vertical transmission B. ovis. Rhipicephalus bursa ticks derived vertically from F₁ to F₄ generations kept high levels of infection (98% in F₃ adults), and consistently led to severe clinical babesiosis in both immunosuppressed and immunocompetent sheep. Although all feeding stages became infected while feeding on their hosts, only adult ticks were able to transmit the parasite to vertebrate hosts. Our findings demonstrate that B. ovis can be transmitted vertically through several tick generations, while preserving its ability to cause severe disease, even without selective pressure. The virulent, mono-infected B. ovis strain developed in this study will provide an infectious challenge model for future vaccine and pathogenesis studies under field-relevant conditions.

The 11th International Symposium on Phlebotomine Sand flies (ISOPS XI) took place in Portorož, Slovenia, in September 2024 and brought together experts from around the world to discuss recent advances in the biology, ecology and control of phlebotomine sand flies and the pathogens they transmit. This report summarises the key findings of the symposium and is organised thematically by session. Key topics included the development of refined experimental models of Leishmania transmission, new insights into the interactions between vector, parasite and microbiota, and the detection of Leishmania donovani in new geographic regions. Advances in molecular diagnostics and surveillance technologies were emphasised, as were emerging concerns about insecticide resistance. The potential of paratransgenesis and symbiont-based vector control approaches was also emphasised. In a separate session, the CLIMOS project was presented, which integrates climate monitoring, ecological modelling and public health tools to develop an early warning system (EWS) for sand fly-borne diseases. Overall, the contributions to the symposium reflect the dynamic development of sand fly research in response to global environmental change and emphasise the importance of international collaboration in combating emerging vector-borne diseases.

Tick-borne pathogens, particularly Babesia and Theileria species, are major threats to cattle production, causing economically significant diseases such as babesiosis and theileriosis. In this study, a real-time SYBR Green PCR assay was developed to detect Babesia and Theileria species in hard ticks (N = 65) and cattle blood samples (N = 143) from Thailand. Using primers targeting the mitochondrial cytochrome b gene for Babesia and the nuclear 18S rRNA gene for Theileria, the assay measured specific melting temperatures (Tm) for each species. The results showed distinct Tm values for Babesia bigemina (74.38 ± 0.04 °C), Babesia bovis (75.7 ± 0.06 °C), Theileria orientalis (74.61 ± 0.03 °C), Theileria sinensis (75.84 ± 0.03 °C), and Theileria annulata (74.06 ± 0.03 °C). The assay demonstrated high specificity, with a cutoff cycle threshold of < 35 cycles and a minimum detectable concentration of 10 copies/μL. Significant species differences in melting curves were confirmed using Tukey's HSD test (p < 0.05). Theileria orientalis was detected in 8.4% of cattle blood samples, while T. sinensis was found in 25.9%, and B. bigemina in 0.7%. Theileria orientalis was also detected in 7.7% of tick samples, T. sinensis in 16.9%, and B. bigemina in 6.1%. The assay returned negative results for all non-target blood and tissue pathogens tested for specificity. This robust, high-throughput assay is highly effective for monitoring Babesia and Theileria infections, facilitating close surveillance and intervention efforts against tick-borne diseases in cattle.