Control Of Helminth Infections Research Articles

Refugia, climatic conditions and farm management factors as drivers of adaptation in Nematodirus battus populations

Parasites are known for their ability to rapidly adapt to changing conditions. For parasitic helminths, changes in climate, along with farming and management practices associated with the intensification of livestock farming, provide novel challenges which can impact on their epidemiology and control. The sustainability of livestock production partially relies on effective control of helminth infection. Therefore, understanding changes in parasite behaviour, and what drives these, is of great importance. Nematodirus battus is an economically important helminth in the UK and temperate regions. Its infective larvae typically overwinter in eggs on pasture and hatch synchronously in spring, causing acute disease in lambs. Attempts to control disease typically rely on whole-flock benzimidazole (BZ) treatments. In recent years, the emergence of BZ-resistance, alongside the hatching of eggs without the classical over-winter ‘chill stimulus’, have made N. battus more difficult to control. In three previous studies, after collecting a large number of N. battus populations alongside farm management data from commercial farms, we explored the prevalence of genetic mutations associated with BZ-resistance (n = 253 farms), the ability of eggs to hatch with and without a chill stimulus (n = 90 farms) and how farm management practices varied throughout the UK (n = 187 farms). In the present study, we identify factors which may be acting as drivers, or barriers, to either the development of resistance or the variable hatching behaviour of N. battus eggs. Generalised linear mixed effect models were applied to regress experimental hatching and genotyping data on farm management and additional environmental data. Both variable hatching and resistance development appeared associated with the maintenance of parasite refugia as well as grazing management, particularly reseeding of pasture routinely grazed by young lambs each spring and the practice of set-stocked grazing. Effective quarantine measures were identified as the main protective factor for the development of BZ-resistance whereas set stocked grazing and population bottlenecks, resulting from reseeding heavily contaminated pastures, were risk factors. Spring maximum temperature and other climatic factors were associated with ‘typical’ hatching of eggs following a chill stimulus whilst several management factors were linked with hatching without prior chilling. For example, practices which reduce parasite numbers on pasture (e.g. re-seeding) or restrict availability of hosts (e.g. resting fields), were found to increase the odds of non-chill hatching. Retention of the timing of lambing and infection level of the host within the fitted model indicated that requirement for a chill stimulus prior to hatching may be plastic, perhaps subject to change throughout the grazing season, in response to immune development or parasite density-dependence within the host. Further investigation of the influence of the factors retained within the fitted models, particularly the theme of parasite refugia which was highlighted in relation to both the presence of BZ-resistance alleles and alternative hatching, is required to establish robust, sustainable parasite control and farm management strategies.

Is there any change in the prevalence of intestinal or cardiopulmonary parasite infections in companion animals (dogs and cats) in Germany between 2004-2006 and 2015–2017? An assessment of the impact of the first ESCCAP guidelines

Main objective of the present nationwide study was to assess the impact of the ESCCAP guideline for the control of worm infections in dogs and cats 8–10 years after its first publication in Germany. A secondary aim was to determine the prevalence of canine and feline cardiopulmonary nematodes and intestinal protozoa. Faecal samples of 53,693 dogs and 26,491 cats in 2004–2006 as well as of 129,578 dogs and 45,709 cats in 2015–2017 routinely submitted by veterinarians to a private veterinary laboratory were examined using appropriate parasitological methods.In dogs, the prevalence of Toxocara and taeniid egg shedding was significantly lower in 2015–2017 (3.8 % and 0.16 %, respectively) than in 2004–2006 (4.6 % and 0.27 %, respectively). The prevalence of hookworm and Capillaria eggs was higher in the second study period (2.3 % and 0.77 %, respectively) than in the first (1.3 % and 0.6 %, respectively). For Toxascaris leonina (0.55–0.6 %) and Trichuris (0.8–0.9 %), the difference was not significant between the study periods. Dogs shed more often Angiostrongylus vasorum larvae in the second study (3.1 %) than in the first (1.0 %), whereas the prevalence of Crenosoma vulpis did not change significantly (2.2–2.6 %). Cystoisospora canis and C. ohioensis-like infections were less detected in the second study period (1.0 % and 2.1 %, respectively) than in the first (1.8 % and 2.7 %, respectively). Neospora-like oocysts and Sarcocystis sporocysts were more prevalent in the second study period (0.19 % and 0.13 %, respectively) than in the first (0.13 % and 0.06 %, respectively). The percentage of Giardia or Cryptosporidium coproantigen-positive samples was lower in the second study period (18.9 % and 6.7 %, respectively) than in the first (22.8 % and 10.0 %, respectively).In cats, the prevalence of egg shedding of T. cati, Capillaria and taeniids was significantly lower in 2015–2017 (3.5 %, 0.25 % and 0.1 %, respectively) than in 2004–2006 (4.8 %, 0.54 % and 0.22 %, respectively). No difference was recorded for hookworms (0.12–0.13 %) and Ts. leonina (0.04–0.05 %). Aelurostrongylus-like larvae were detected more often in the second study period (6.5 %) than in the first (2.6 %). Infections with Cystoisospora felis, C. rivolta, Toxoplasma-like coccids and Sarcocystis were less prevalent in the second study period (1.9 %, 0.7 %, 0.24 % and 0.02 %, respectively) than in the first (2.7 %, 1.1 %, 0.36 % and 0.1 %, respectively). The percentage of Giardia or Cryptosporidium coproantigen-positive samples was significantly lower in the second study period (10.6 % and 4.8 %, respectively) than in the first (15.4 % and 8.3 %, respectively).Although these results indicate a decline of the occurrence of most canine and feline intestinal parasites in Germany over the years, a transmission risk of zoonotic parasites remains. Therefore, the control of helminth infections in domestic dogs and cats continues to be a challenge for veterinarians and pet owners.

A prevalence-based transmission model for the study of the epidemiology and control of soil-transmitted helminthiasis.

Much effort has been devoted by the World Health Organization (WHO) to eliminate soil-transmitted helminth (STH) infections by 2030 using mass drug administration targeted at particular risk groups alongside the availability to access water, sanitation and hygiene services. The targets set by the WHO for the control of helminth infections are typically defined in terms of the prevalence of infection, whereas the standard formulation of STH transmission models typically describe dynamic changes in the mean-worm burden. We develop a prevalence-based deterministic model to investigate the transmission dynamics of soil-transmitted helminthiasis in humans, subject to continuous exposure to infection over time. We analytically determine local stability criteria for all equilibria and find bifurcation points. Our model predicts that STH infection will either be eliminated (if the initial prevalence value, y(0), is sufficiently small) or remain endemic (if y(0) is sufficiently large), with the two stable points of endemic infection and parasite eradication separated by a transmission breakpoint. Two special cases of the model are analysed: (1) the distribution of the STH parasites in the host population is highly aggregated following a negative binomial distribution, and (2) no density-dependent effects act on the parasite population. We find that disease extinction is always possible for Case (1), but it is not so for Case (2) if y(0) is sufficiently large. However, by introducing stochastic perturbation into the deterministic model, we discover that chance effects can lead to outcomes not predicted by the deterministic model alone, with outcomes highly dependent on the degree of worm clumping, k. Specifically, we show that if the reproduction number and clumping are sufficiently bounded, then stochasticity will cause the parasite to die out. It follows that control of soil-transmitted helminths will be more difficult if the worm distribution tends towards clumping.

Age-dependent rise in IFN-γ competence undermines effective type 2 responses to nematode infection

The efficient induction of type 2 immune responses is central to the control of helminth infections. Previous studies demonstrated that strong Th1 responses driven by intracellular pathogens as well as a bias for type 1 activity in senescent mice impedes the generation of Th2 responses and the control of intestinal nematode infections. Here, we show that the spontaneous differentiation of Th1 cells and their expansion with age restrains type 2 immunity to infection with the small intestinal nematode H. polygyrus much earlier in life than previously anticipated. This includes the more extensive induction of IFN-γ competent, nematode-specific Th2/1 hybrid cells in BALB/c mice older than three months compared to younger animals. In C57BL/6 mice, Th1 cells accumulate more rapidly at steady state, translating to elevated Th2/1 differentiation and poor control of parasite fitness in primary infections experienced at a young age. Blocking of early IFN-γ and IL-12 signals during the first week of nematode infection leads to sharply decreased Th2/1 differentiation and promotes resistance in both mouse lines. Together, these data suggest that IFN-γ competent, type 1 like effector cells spontaneously accumulating in the vertebrate host progressively curtail the effectiveness of anti-nematode type 2 responses with rising host age.

Increase in the reproductive efficiency of primiparous and multiparous Nellore cows following moxidectin treatment at the onset of a fixed-time artificial insemination protocol

The aim of the present study was to evaluate the effects of moxidectin (MOX – 200 µg/kg/sc) administered on Day Zero of a fixed-time artificial insemination (FTAI) protocol on fecal egg counts and the reproductive efficiency of primiparous and multiparous Nellore beef cows kept in the pasture. A simulation was performed of the possible correlation between the fecal egg count and helminth load per animal (cow versus calf). An economic analysis was performed of the magnitude of the return over investment (ROI) of moxidectin treatment at the onset of the FTAI protocol. Three experiments were performed with a total of 6,320 Nellore females (primiparous and multiparous) and calves approximately 45 days old. The animals were subdivided into two groups: control and treated with MOX subcutaneously on Day 0 concomitant with the reproduction protocol adopted in the first FTAI. Egg counts per gram of feces (EPG) were performed on Days 0 and 11. Resynchronization of ovulation (RO) was performed in cows diagnosed with negative pregnancy 30 days after the first FTAI. Nellore bulls were used for natural service at a proportion of one bull per 25 Nellore cows 10 days after the second diagnosis of gestation (D92). The results of the three experiments indicated that treatment with MOX at the beginning of the FTAI protocol (Day 0) increased the pregnancy rate at the first FTAI and had no effect on the pregnancy rate at the second FTAI (RO), leading to a larger number of pregnant cows at the end of the breeding season, with an ROI of 44.9 and 19.0 for primiparous and multiparous cows, respectively. The mean parasite load (EPG) decreased significantly after treatment with moxidectin in both primiparous and multiparous cows. However, the statement that the difference in the pregnancy rate for the treated cows occurred due to the control of helminth infection should be interpreted with caution. Further studies are needed to gain an understanding the unknown physiological mechanisms of moxidectin that could be affecting the reproductive results.

Time for malaria control in school-age children

School-age children (6–15 years) bear an under-appreciated burden of malaria. Across sub-Saharan Africa, the prevalence of infection peaks in this age group, and an estimated 200 million school-age children are at risk of malaria. 1 Pinchoff J Chaponda M Shields TM et al. Individual and household level risk factors associated with malaria in Nchelenge District, a region with perennial transmission: a serial cross-sectional study from 2012 to 2015. PLoS One. 2016; 11e0156717 Crossref PubMed Scopus (24) Google Scholar , 2 Mwandagalirwa MK Levitz L Thwai KL et al. Individual and household characteristics of persons with Plasmodium falciparum malaria in sites with varying endemicities in Kinshasa Province, Democratic Republic of the Congo. Malar J. 2017; 16: 456 Crossref PubMed Scopus (15) Google Scholar Infection in this age group not only threatens child health and education, but also serves as a source of onward parasite transmission, undermining elimination efforts. 3 Coalson JE Cohee LM Buchwald AG et al. Simulation models predict that school-age children are responsible for most human-to-mosquito Plasmodium falciparum transmission in southern Malawi. Malar J. 2018; 17: 147 Crossref PubMed Scopus (17) Google Scholar Universal malaria interventions, such as bed nets and access to prompt diagnosis and treatment, are assumed to cover this age group. However, school-age children are the group least likely to benefit from these interventions. 4 Olapeju B Choiriyyah I Lynch M et al. Age and gender trends in insecticide-treated net use in sub-Saharan Africa: a multi-country analysis. Malar J. 2018; 17: 423 Crossref PubMed Scopus (19) Google Scholar , 5 Coalson JE Cohee LM Walldorf JA et al. Challenges in treatment for fever among school-age children and adults in Malawi. Am J Trop Med Hyg. 2019; 100: 287-295 Crossref PubMed Scopus (3) Google Scholar Thus, interventions specifically targeting this age group are needed. Schools provide ready access to this population and are successfully involved in addressing other health concerns in children, such as feeding for nutritional deficiencies (see the World Food Programme report on state of school feeding worldwide) and deworming campaigns for control of helminth infections (see the WHO Neglected Tropical Disease progress dashboard for preventive chemotherapy diseases).

Hand hygiene intervention to optimise soil-transmitted helminth infection control among primary school children: the Mikono Safi cluster randomised controlled trial in northwestern Tanzania

BackgroundSoil-transmitted helminth (STH) infections are highly prevalent in resource-limited countries. We assessed the effect of a combination intervention aiming to enhance handwashing with soap on STH reinfection following mass drug administration among primary school children in Kagera region, Northwestern Tanzania.MethodsWe conducted a cluster randomised trial in sixteen primary schools with known high STH prevalence. Schools were randomly assigned in a 1:1 ratio to either receive the intervention or continue with routine health education. The intervention included teacher-led classroom teaching, parental engagement sessions, environmental modifications and improved handwashing stations. The evaluation involved two cross-sectional surveys in a representative sample of students, with the end-line survey conducted 12 months after the baseline survey. The primary outcome was the combined prevalence of Ascaris lumbricoides and Trichuris trichiura infections at the end-line survey. Secondary outcomes included reported handwashing behaviour, the prevalence and intensity of individual STHs, and hand contamination with STH ova and coliform bacteria. End-line STH prevalence and intensity were adjusted for baseline differences of potential confounders.ResultsAt the end-line survey, 3081 school children (1566 from intervention schools and 1515 from control schools) provided interview data and stool specimens. More school children in the intervention group reported the use of water and soap during handwashing compared to school children in the control group (58% vs. 35%; aOR=1.76, 95%CI 1.28–2.43, p=0.001). The combined prevalence of A. lumbricoides and T. trichiura infections was 39% in both trial arms (aOR = 1.19; 95%CI 0.74–1.91). The prevalence of A. lumbricoides was 15% in the intervention and 17% in the control arm (aOR =1.24, 95%CI 0.59–2.59) and that of T. trichiura was 31% in both arms (aOR=1.17, 95%CI 0.73–1.88). No significant differences were found for STH infection intensity in both the main study and the hand contamination sub-study.ConclusionsThe intervention was effective in increasing reported handwashing behaviour at school, but failed to show a similar effect in the home. The intervention had no effect on STH infection, possibly due to infection in the home environment, other transmission routes such as contaminated water or food or limited changes in school children’s handwashing behaviour.Trial registrationThe trial was registered on June 21, 2017, by the International Standard Randomised Controlled Trial Number (ISRCTN45013173).

Situation of and phenotypic markers of susceptibility to helminth infection among sheep on farms in the Brazilian cerrado biome.

This study aimed to determine the intensity, seasonality, and distribution by genera of, as well as to identify phenotypic markers of susceptibility to, gastrointestinal parasites among sheep on farms within the Brazilian savanna (cerrado) biome. We evaluated 1271 sheep, on seven farms, during the rainy season (in December 2017 and December 2018) and dry season (in July 2018 and July 2019). Parasitological evaluation was based on culture and EPG. We calculated hematocrit, as well as the body condition score and feces score. Of the sheep evaluated, 34.15% had moderate-to-severe parasitic infection. The factors of herds' phenotypic characterization about helminth infections were (p ≤ 0.05 for all): anemia (OR = 5.72); leanness (OR = 1.80); loose stools or diarrhea (OR = 1.54); breed other than Santa Inês (OR = 2.31); "weaned lamb" category (OR = 4.76); "lambing ewe" category (OR = 4.66); and dry season (OR = 2.37). Haemonchus, Trichostrongylus, Oesophagostomum, and Cooperia accounted for 76.40%, 20.23%, 2.89%, and 0.47%, respectively, of the helminth genera identified, with their proportional distributions being comparable between the rainy and dry seasons. Changes in health management, with regard to helminth infection control, are urgently needed in order to combat the disease more effectively and sustainably.

Hand hygiene intervention to optimize helminth infection control: Design and baseline results of Mikono Safi-An ongoing school-based cluster-randomised controlled trial in NW Tanzania.

IntroductionSoil transmitted helminths (STH) can affect over 50% of children in some parts of Tanzania. Control measures involve annual deworming campaigns in schools, but re-infection is rapid. This paper presents the design and baseline survey results of an ongoing school-based cluster-randomised controlled trial in Kagera region, NW Tanzania. The trial aims to determine whether the effect of routine deworming on the prevalence of Ascaris lumbricoides and Trichuris trichiura infections among school aged children can be sustained when combined with a behaviour change intervention promoting handwashing with water and soap.MethodsAs part of the trial, a total of 16 schools were randomised to receive the intervention (N = 8) or as controls (N = 8). Randomisation was stratified per district and restricted to ensure pre-trial STH prevalence was balanced between study arms. The combination intervention to be tested comprises class-room based teacher-led health education, improvement of handwash stations, coloured nudges to facilitate handwashing and parental engagement sessions. The impact evaluation involves two cross-sectional surveys conducted at baseline and endline. The objectives of the baseline survey were: (i) to confirm whether the deworming campaign was successful, and identify and treat students still infected about 2 weeks after deworming, (ii) to document any baseline differences in STH prevalence between trial arms, and (iii) to assess handwashing behaviours, and access to water and sanitation at school and home. We randomly sampled 35 students per class in Grades 1–6 (an average of 200 children per school), stratified to ensure equal representation between genders. Assenting students were interviewed using a structured questionnaire and asked to provide a stool specimen.ResultsResults of the baseline survey conducted about 2 weeks after deworming shows balanced demographic and STH prevalence data across trial arms. We observed a low prevalence of ascariasis (< 5%) as expected; however, the prevalence of trichuriasis was still about 35% in both arms.ConclusionThe randomisation procedure was successful in achieving a balanced distribution of demographic characteristics and helminth infections between trial arms. The intervention is being rolled out. The current deworming treatment regimen may need to be revised with regards to the treatment of trichuriasis.

Modeling the Effects of Helminth Infection on the Transmission Dynamics of Mycobacterium tuberculosis under Optimal Control Strategies.

A deterministic mathematical model for the transmission and control of cointeraction of helminths and tuberculosis is presented, to examine the impact of helminth on tuberculosis and the effect of control strategies. The equilibrium point is established, and the effective reproduction number is computed. The disease-free equilibrium point is confirmed to be asymptotically stable whenever the effective reproduction number is less than the unit. The analysis of the effective reproduction number indicates that an increase in the helminth cases increases the tuberculosis cases, suggesting that the control of helminth infection has a positive impact on controlling the dynamics of tuberculosis. The possibility of bifurcation is investigated using the Center Manifold Theorem. Sensitivity analysis is performed to determine the effect of every parameter on the spread of the two diseases. The model is extended to incorporate control measures, and Pontryagin's Maximum Principle is applied to derive the necessary conditions for optimal control. The optimal control problem is solved numerically by the iterative scheme by considering vaccination of infants for Mtb, treatment of individuals with active tuberculosis, mass drug administration with regular antihelminthic drugs, and sanitation control strategies. The results show that a combination of educational campaign, treatment of individuals with active tuberculosis, mass drug administration, and sanitation is the most effective strategy to control helminth-Mtb coinfection. Thus, to effectively control the helminth-Mtb coinfection, we suggest to public health stakeholders to apply intervention strategies that are aimed at controlling helminth infection and the combination of vaccination of infants and treatment of individuals with active tuberculosis.

Bridging research to policy for the prevention and control of parasitic neglected tropical diseases in the Philippines: the War on Worms campaign

BackgroundIn the Philippines, the Department of Health (DOH) is the governing agency for the health system and is mandated to provide national policy direction and develop national plans, technical standards, and guidelines on health. Under the Local Government Code of 1991, local government units (LGUs) were granted autonomy and responsibility for provision of health services. This decentralisation has posed challenges in terms of capacity and coordination. Here, we describe the War on Worms (WOW) campaign, which was developed and implemented to provide technical support to DOH and LGUs in the prevention and control of helminth infections in the Philippines. MethodsIn 2012, the WOW Campaign was implemented in Davao del Norte, Philippines. Advocacy fora were conducted to forge partnerships between different sectors and solicit support of local officials. Health workers received training and resources, and social mobilisation activities were conducted in the community to raise awareness of helminth control. With the endorsement of the Department of Education (DepEd), children in schools aged 5–12 years were given anthelmintics via school-based, teacher-assisted mass drug administration (MDA). Combined MDA for soil-transmitted helminthiasis (STH) and schistosomiasis was eventually implemented in schistosomiasis-endemic sites to simplify and increase efficiency of treatment for both infections. Parasite assessment using the Kato-Katz technique was conducted in sentinel sites at the beginning of the project to provide baseline helminth status in the area. After MDA, we monitored coverage rates, and adherence to the programme. Follow-up parasitological assessment after four rounds of MDA was also conducted to monitor outcomes of the deworming programme. FindingsIn its 5 years of implementation, the WOW Campaign has generated evidence for policy formulation to improve control of intestinal helminthiasis. The combined MDA among school-aged children showed a marked increase from the 31% coverage rate in 2013 to 69% in 2014. This increasing trend continued with the 75% and 90% combined MDA coverage rates in 2015 and 2016, respectively. The baseline and follow-up parasitological assessments conducted in 2012 and 2015, respectively, showed reductions in the prevalence of STH and schistosomiasis. In 2012, the baseline parasitological assessment in school children showed a cumulative STH prevalence and moderate-to-heavy intensity STH prevalence of 14·7% and 0·5%, respectively, with 3·1% schistosomiasis prevalence. In 2015, the follow-up parasitological assessment showed a decrease in the prevalence of STH and moderate-to-high intensity STH to 4·2% and 0·3%, respectively. Schistosomiasis prevalence also showed a reduction to 0·3%, meeting WHO target schistosomiasis prevalence of <1%. Lessons from the WOW Campaign, such as the school-based teacher-assisted combined MDA, increased coverage rates, and decreased prevalence rates, contributed in the formulation of policies for the National School Deworming Day (NSDD), National School Deworming Month (NSDM), and Harmonized Schedule and Combined Mass Drug Administration (HSCMDA). Likewise, a memorandum of understanding among the DOH, Department of Education, Department of Interior, and local governments was developed for the implementation of policies. InterpretationAside from generating evidence to inform programmes and policies, research serves as a good platform to initiate intersectoral collaboration. Support of local governments was crucial in the implementation of the campaign. Initiating intersectoral collaboration and soliciting the support of local officials are key steps in bridging research to policy, particularly in decentralised health systems like the Philippines. FundingAsian Community Trust.

Exploration of extracellular vesicles from Ascaris suum provides evidence of parasite–host cross talk

ABSTRACTThe prevalent porcine helminth, Ascaris suum, compromises pig health and reduces farm productivity worldwide. The closely related human parasite, A. lumbricoides, infects more than 800 million people representing a disease burden of 1.31 million disability-adjusted life years. The infections are often chronic in nature, and the parasites have a profound ability to modulate their hosts’ immune responses. This study provides the first in-depth characterisation of extracellular vesicles (EVs) from different developmental stages and body parts of A. suum and proposes the role of these vesicles in the host–parasite interplay. The release of EVs from the third- (L3) and fourth-stage (L4) larvae and adults was demonstrated by transmission electron microscopy (TEM), and sequencing of EV-derived RNA identified a number of microRNAs (miRNAs) and transcripts of potential host immune targets, such as IL-13, IL-25 and IL-33, were identified. Furthermore, proteomics of EVs identified several proteins with immunomodulatory properties and other proteins previously shown to be associated with parasite EVs. Taken together, these results suggest that A. suum EVs and their cargo may play a role in host–parasite interactions. This knowledge may pave the way to novel strategies for helminth infection control and knowledge of their immune modulatory potential.

A Review on Ecosegregation and Parasitocoenosis of Helminthes: Perspective to Health and Sustainability

The parasitic helminthes are a group of invertebrates and including animals which have been adapted themselves to the parasitic mode of life. These are belonging to two important phyla namely, platyhelminthes and Aschelminthes. The parasites are those organism which lives at the expense of other organism, and in return causes injury or harm to the host. Thus it is an association in which one organism i.e. the parasite, is benefited while another one, the host, is harmed is called parasitism; however, behavior, occurrence, establishment and cuases of of parasitism known as parasitocoenosis. The parasitism has evolved accidently as a result of contact between different forms of animals, mainly for the purpose of obtaining nourishment and receiving shelter. An ideal parasite never causes too much harm to its host because if the host dies the parasite depending upon the host will also have to die. The parasitism and parasitocoenosis is a matter of conflict and ambiguity either it is structured association based on ecosegregation and microhabitat specificity or a stochastic assemblages and accidental contact due to utilization of common habitat and life style. The helminthes zoonotic infections are among the most common on erath and are responsible for major human infectious diseases. Some of the most important and well known human zoonoses are caused by parasitic helminthes including anisakiasis, trichinellosis, cysticercosis, echinococcosis, schistosomiasis, etc. However, along with social, epidemiological and environmental changes, together with improvements in our ability to diagnose helminth infections, several neglected parasite species are now fast-becoming recognized as important zoonotic diseases of humans, e.g., anasakiasis, several fish-borne trematodiasis and fasciolosis. In the present review, we discuss the current status of the primary helminth zoonotic infections with particular emphasis on their ecosegregation and parasitocoenosis. Advances in molecular biology, proteomics and the release of helminth genome-sequencing project data are revolutionizing parasitology research. The authors wish to suppose and hupothesize the application of these powerful experimental approaches, and their potential benefits to helminth biology and definitely these contrivances will be the mile stone to the future control of helminth infections of animals and humans.

Manipulation of the balance between Th2 and Th2/1 hybrid cells affects parasite nematode fitness in mice.

T-helper type 2 (Th2) responses are central to the control of helminth infections, but sensitive to opposing cytokine signals favoring Th1 priming. We previously reported on GATA-3+ T-bet+ Th2/1 hybrid cell differentiation in helminth mono-infections, resulting in a substantial proportion of cells coproducing IFN-γ next to Th2 cytokines. Here, we demonstrate Th2/1 cells as the major source of parasite-specific IFN-γ production in acute and chronic infections with the enteric nematode Heligmosomoides polygyrus. Th2/1 cells differentiated from naive precursors and accumulated in spleen and intestine of infected mice, resulting in increased systemic and mucosal IFN-γ production. IFN-γ supplementation early during infection supported Th2/1 differentiation, associated with elevated parasite fecundity and the maintenance of high worm burdens in the chronic stage of infection, whereas mice lacking IFN-γ signals generated poor Th2/1 responses and restricted parasite fecundity more efficiently. These findings suggest that Th2/1 hybrid responses take part in immune regulation during helminth infection and restrain effective anti-helminth immunity.

Effects of dietary intake of garlic on intestinal trematodes.

The current strategy for the control of helminth infections relies on chemotherapy. However, resistance appearance is promoting the necessity of developing new drugs against trematodes. Herein, potential trematocidal effects of garlic (Allium sativum) are investigated in the context of intestinal foodborne trematodes, employing the Echinostoma caproni-mouse model. Daily administration of dietary doses of garlic was conducted in three groups of mice: (i) before infection (prophylaxis), (ii) after infection (therapeutic) and (iii) both, before and after infection (continuous). A fourth group of mice, not exposed to garlic, was used as control. No differences in worm recovery, fecundity and local cytokine expression profiles were found with respect to control infections. However, considerable alterations in tegument structure, including swelling, furrowing, vacuolization and changes in secretory bodies were detected in garlic-exposed parasites using scanning and transmission electron microscopy. Protein secretion was markedly reduced in response to garlic, whereas up-regulation of several proteins, such as major vault protein and tER-ATPase, was observed in treated worms. The results presented herein provide new insights in the anthelminthic activity of bioactive garlic compounds and the manner that parasites respond to toxins.

Effect of creep-fed supplement on the susceptibility of pasture-grazed suckling lambs to gastrointestinal helminths

This study evaluated the effect of creep feeding a protein supplement on the susceptibility of suckling lambs to infection with gastrointestinal helminths. Male and female lambs were grazed on Brachiaria spp. pastures next to their mothers. Animals were allocated to one of two treatments: creep feeding (261g/d) and control (no supplementation). The trial period was the suckling of lambs during two years of study: May-October 2013 and March-July 2014. Supplementary creep feeding of lambs improved animal performance (P<0.05). Creep-fed lambs reached 18kg body weight in 64 d, but unsupplemented lambs required 77 d to reach the same weight. Lambs were susceptible to helminth infection during lactation; lambs in both treatments had high fecal egg counts (FECs), with means >1000 eggs per gram, as early as 45days of age, when the daily grazing time per animal increased. Creep feeding reduced the FECs of suckling lambs >60days of age in infections dominated by Haemonchus contortus. Totals of 20 and 48 anthelmintic treatments were administered to the supplemented and unsupplemented animals, respectively. The effect of this variable, however, was significant (P<0.05) only after 60days, when nine and 28 treatments had been administered to the supplemented and unsupplemented lambs, respectively. The number of strongyloid larvae recovered from the paddock did not differ significantly (P >0.05) between the two treatments, indicating similar challenges by infective larvae to both groups. The supplementation of lambs by creep feeding can thus be a strategy for the sustainable control of helminth infection, because it reduces the dependence on anthelmintic treatment.

High prevalence of Strongyloides stercoralis in school-aged children in a rural highland of north-western Ethiopia: the role of intensive diagnostic work-up.

BackgroundSoil-transmitted helminthiases (hookworms, Ascaris lumbricoides and Trichuris trichiura) are extremely prevalent in school-aged children living in poor sanitary conditions. Recent epidemiological data suggest that Strongyloides stercoralis is highly unreported. However, accurate data are essential for conducting interventions aimed at introducing control and elimination programmes.MethodsWe conducted a cross-sectional survey of 396 randomly selected school-aged children in Amhara region in rural area in north-western Ethiopia, to assess the prevalence of S. stercoralis and other intestinal helminths. We examined stools using three techniques: conventional stool concentration; and two S. stercoralis-specific methods, i.e. the Baermann technique and polymerase chain reaction. The diagnostic accuracy of these three methods was then compared.ResultsThere was an overall prevalence of helminths of 77.5%, with distribution differing according to school setting. Soil-transmitted helminths were recorded in 69.2%. Prevalence of S. stercoralis and hookworm infection was 20.7 and 54.5%, respectively, and co-infection was detected in 16.3% of cases. Schistosoma mansoni had a prevalence of 15.7%. Prevalence of S. stercoralis was shown 3.5% by the conventional method, 12.1% by the Baermann method, and 13.4% by PCR, which thus proved to be the most sensitive.ConclusionsOur results suggest that S. stercoralis could be overlooked and neglected in Ethiopia, if studies of soil-transmitted helminths rely on conventional diagnostic techniques alone. A combination of molecular and stool microscopy techniques yields a significantly higher prevalence. In view of the fact that current control policies for triggering drug administration are based on parasite prevalence levels, a comprehensive diagnostic approach should instead be applied to ensure comprehensive control of helminth infections.

RELMs in the Realm of Helminths

Resistin-like molecule (RELM) proteins are essential for immunity to helminths. Recently, Chen and collaborators identified a dominant role for RELMα over RELMβ in host immunity to Nippostrongylus brasiliensis using a double knockout system. The study highlighted how important and yet divergent the contributions of these proteins are in the control of helminth infections.

Drugs for cat and dog worm elimination: what do we have now and what do we need?

Parasitic worms (helminths) have accompanied domesticated cats and dogs for thousands of years and are still prevalent. This is true not only in the developed world, but especially where there is wide scale poverty, including large parts of Southeast Asia and the Western Pacific Region. The global strategy for the control of helminth infections is still morbidity control and reduction or elimination of public health risks. Between 1960 and 1980, astonishing success was accomplished in anthelmintic improvement for animals. In those 20 years, drugs with varied structure, innovative activity and privileged safety were produced. The subsequent years have been spent modifying existing molecules with niche activity (parasite-host research), improving delivery systems and combating the relentless spread of drug resistance. For the years to come, existing technologies are required to design and produce new drugs and biological controls. This article considers the current chemical options for deworming pets and points out the knowledge and treatment gaps that need addressing.

Global Health and Tropical Medicine in the Twenty-First Century: A Renewed Interest in the Understanding and the Control of Helminth Infections

The twenty-first century has shown an expansion and renewed excitement in global health, and tropical medicine is one of the critical drivers leading this global health phenomenon. Among the tropical diseases, helminth infections rank first in the list of diseases causing the highest disability adjusted life years. Because of the importance of helminth infections and their impact on global health, we highlight in this commentary an elegant compilation of reviews recently published by Springer, which provide a detailed overview of the biology, pathology, diagnosis, treatment, and prevention strategies for the helminths that can cause human disease and morbidity.