Canine soil-transmitted helminths (STHs) cause important zoonoses in the tropics, with varying degrees of intensity of infection in humans and dogs. This study aimed to investigate the prevalence and associated risk factors for STHs in community dogs residing in Grenada, West Indies. In May 2021, 232 canine fecal samples were examined for zoonotic helminths by microscopy (following flotation), and genomic DNA from a subset of 211 of these samples were subjected to multiplex qPCR for the detection and specific identification of hookworms, Toxocara spp. and Strongyloides. Microscopic examination revealed that 46.5% (108/232, 95% CI 40–52.9), 9% (21/232, 95% CI 5.35–12.7) and 5.2% (12/232, 95% CI 2.3–8) of the samples contained eggs of Ancylostoma spp., Toxocara spp. and Trichuris vulpis, respectively. Multiplex qPCR revealed that, 42.2% (89/211, 95% CI 35.5–48.8) were positive for at least 1 zoonotic parasite. Of these, 40.8% (86/211, 95% CI 34.1–47.3) of samples tested positive for Ancylostoma spp., 36% (76/211, 95% CI 29.5–42.9) were positive for A. caninum, 13.3% (28/211, 95% CI 9–18.6) for A. ceylanicum, 5.7% for T. canis (12/211, 95% CI 2.97–8.81) and 1% (2/211, 95% CI 0–2.26) for Strongyloides spp. (identified as S. stercoralis and S. papillosus by conventional PCR-based Sanger sequencing). Using a multiple logistic regression model, a low body score and free-roaming behaviour were significant predictors of test-positivity for these parasitic nematodes in dogs (P < 0.05). Further studies of zoonotic STHs in humans should help elucidate the public health relevance of these parasites in Grenada.

Soil-transmitted nematodes (STNs) place a tremendous burden on health and economics worldwide with an estimate of at least 1.5 billion people, or 24% of the population, being infected with at least 1 STN globally. Children and pregnant women carry the heavier pathological burden, and disease caused by the blood-feeding worm in the intestine can result in anaemia and delays in physical and intellectual development. These parasites are capable of infecting and reproducing in various host species, but what determines host specificity remains unanswered. Identifying the molecular determinants of host specificity would provide a crucial breakthrough towards understanding the biology of parasitism and could provide attractive targets for intervention. To investigate specificity mechanisms, members of the hookworm genus Ancylostoma provide a powerful system as they range from strict specialists to generalists. Using transcriptomics, differentially expressed genes (DEGs) in permissive (hamster) and non-permissive (mouse) hosts at different early time points during infection with A. ceylanicum were examined. Analysis of the data has identified unique immune responses in mice, as well as potential permissive signals in hamsters. Specifically, immune pathways associated with resistance to infection are upregulated in the non-permissive host, providing a possible protection mechanism that is absent in the permissive host. Furthermore, unique signatures of host specificity that may inform the parasite that it has invaded a permissive host were identified. These data provide novel insight into the tissue-specific gene expression differences between permissive and non-permissive hosts in response to hookworm infection.

Various host and parasite factors interact to determine the outcome of infection. We investigated the effects of two factors on the within-host dynamics of malaria in mice: initial infectious dose and co-infection with a helminth that limits the availability of red blood cells (RBCs). Using a statistical, time-series approach to model the within-host ‘epidemiology’ of malaria, we found that increasing initial dose reduced the time to peak cell-to-cell parasite propagation, but also reduced its magnitude, while helminth co-infection delayed peak cell-to-cell propagation, except at the highest malaria doses. Using a mechanistic model of within-host infection dynamics, we identified dose-dependence in parameters describing host responses to malaria infection and uncovered a plausible explanation of the observed differences in single vs co-infections. Specifically, in co-infections, our model predicted a higher background death rate of RBCs. However, at the highest dose, when intraspecific competition between malaria parasites would be highest, these effects of co-infection were not observed. Such interactions between initial dose and co-infection, although difficult to predict a priori, are key to understanding variation in the severity of disease experienced by hosts and could inform studies of malaria transmission dynamics in nature, where co-infection and low doses are the norm.

Definitive diagnosis of hookworm infection is usually based on the microscopic detection of eggs in a stool sample; however, several cases display a low or irregular egg output. Serodiagnosis can be a useful tool to identify these cases, but conventional tests do not differentiate past from active infections. The aim of this study was to obtain and apply egg yolk polyclonal immunoglobulin (IgY) antibodies to detect immune complexes (ICs) in serum samples from patients infected with hookworm. Hens were immunized with Ancylostoma ceylanicum saline extract, their eggs were collected and then IgY antibodies were extracted and purified. Antibody purity was tested by 12% sodium dodecyl sulphate polyacrylamide gel electrophoresis and specificity was assessed by immunoblotting and immunofluorescence. IgY production was evaluated by kinetics enzyme-linked immunosorbent assay (ELISA). Sandwich ELISA tested the ability of IgY to detect ICs in serum samples, from which diagnostic parameters were calculated. Antibody responses increased steadily from day 7 to 42. In the immunoblotting assay, IgY recognized two protein complexes. The immunofluorescence assay showed no staining in control samples. The sandwich ELISA presented a very high diagnostic value, with a sensitivity of 90% and a specificity of 86.7%. Our pioneer strategy highlights the potential use of egg yolk IgY as a diagnostic test to detect active hookworm infection.

There is a paucity of information on hookworm species in humans, domestic animals and wildlife in southern Africa. Our study aimed to identify hookworm species from stray dogs, humans, and selected wildlife from South Africa. A total of 356 faecal samples were screened for the presence of hookworm-like eggs and subsequently coproculture from the positive samples was carried out to obtain larvae. Hookworm-like eggs were detected in 23.03% (82/356) of samples. Of these samples, 78/296 were from dogs, 3/50 from humans and 1/10 from wildlife. DNA was then isolated from the larvae of 55 positive samples, which were subjected to polymerase chain reaction (PCR), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing of the nuclear ribosomal internal transcribed spacer (ITS1) and 5.8S rRNA region. Presence of Ancylostoma caninum, A. braziliense and A. ceylanicum-like species was recorded in stray dogs and A. caninum was recorded in wildlife and humans, using PCR-RFLP. Although PCR-RFLP results pointed to the presence of A. ceylanicum, we did not get a sequence that matched with A. ceylanicum from GenBank. This may have been due to the low proportion of A. ceylanicum larvae in our samples. Twenty-two of the 27 positive amplicons from stray dogs matched with A. caninum, three with A. braziliense and two had mixed infections of A. braziliense and A. caninum. Sequences from a lion and three humans matched with A. caninum. This is the first confirmation of a patent A. caninum infection in humans as evidenced by the presence of eggs in faeces, with the subsequent larvae from coproculture being identified as A. caninum.

Despite the profound health implications of Necator americanus infection in humans, many aspects of its interaction with the host immune system are poorly understood. Here we investigated the early events at the interface of N. americanus larvae (L3) and human dendritic cells (DCs). Our data show that co-culturing DCs and the larvae trigger ex-sheathing of hookworms rapidly where a majority of DCs are sequestered onto the larval sheath allowing the ex-sheathed larvae to migrate away unchallenged. Intriguingly, DCs show negligible interaction with the ex-sheathed larvae, alluding to differences between the surface chemistry of the larva and its sheath. Furthermore, blocking of two key C-type lectin receptors on DC surface (i.e. DC-SIGN and mannose receptor) resulted in inhibition of ex-sheathing process and DC sequestration, highlighting the importance of C-type lectins on DCs in the induction of the ex-sheathing. Analyses of DC phenotype and cytokine profile after co-culture with the N. americanus larvae showed an immature phenotype as evidenced by the low expression of the maturation markers and cytokines. These data provide new insights into early events at the interface of human DCs and N. americanus larvae and could explain how L3 evade immune recognition upon initial interaction with DCs.

This longitudinal study explored whether aspects of subsistence agriculture were associated with presence and intensity of Ascaris and hookworm in preschool children in rural Panama. Questionnaires were used to collect data on household socio-demographics, child exposure to agriculture and household agricultural practices. Stool samples were collected from children (6 months–5 years) at 3 time points, with albendazole administered after each to clear infections, resulting in 1 baseline and 2 reinfection measures. A novel Agricultural Activity Index (AAI) was developed using principal components analysis to measure the intensity of household agricultural practices. Zero-inflated negative binomial regression models revealed baseline hookworm egg counts were higher if children went to the agricultural plot and if the plot was smaller. Baseline and reinfection Ascaris egg counts were higher if children went to the plot and households had higher AAI, and higher at baseline if the plot was smaller. Caregiver time in the plot was negatively associated with baseline Ascaris egg counts, but positively associated with baseline hookworm and Ascaris reinfection egg counts. Children who spent more time playing around the home were less likely to be infected with Ascaris at baseline. We conclude that preschool child exposure to subsistence agriculture increased Ascaris and hookworm intensity.

This study explored whether the yard environment and child hygiene and play behaviours were associated with presence and intensity of Ascaris and hookworm in preschool children and with eggs and larvae in soil. Data were collected using questionnaires, a visual survey of the yard, soil samples and fecal samples collected at baseline and following re-infection. The presence of eggs/larvae in soil was associated negatively with water storage (eggs) but positively with dogs (eggs) and distance from home to latrine (larvae). Baseline and re-infection prevalences were: hookworm (28·0%, 3·4%); Ascaris (16·9%, 9·5%); Trichuris (0·9%, 0·7%). Zero-inflated negative binomial regression models revealed a higher baseline hookworm infection if yards had eggs or larvae, more vegetation or garbage, and if the child played with soil. Baseline Ascaris was associated with dirt floor, dogs, exposed soil in yard, open defecation and with less time playing outdoors, whereas Ascaris re-infection was associated with water storage, vegetation cover and garbage near the home and not playing with animals. Our results show complex interactions between infection, the yard environment and child behaviours, and indicate that transmission would be reduced if latrines were closer to the home, and if open defecation and water spillage were reduced.

The motility assay is the current gold standard for evaluating drug effects on hookworm larvae and adults, however, among other drawbacks the assay is time consuming, and prone to individual subjectivity. We evaluated six alternative in vitro assays, namely the feeding inhibition assay, the colourimetric AlamarBlue®, MTT formazan and acid phosphatase activity assays, as well as isothermal calorimetry and the xCELLigence System using Ancylostoma ceylanicum third-stage larvae, stimulated third-stage larvae and adults. The performances of the assays were compared to the motility assay using three standard drugs: albendazole, levamisole and ivermectin (100–1 μg/ml). None of the assays investigated offered an advantage over the motility assay, because they were all inapplicable to third-stage larvae, which were presumably metabolically and physically too inactive. Among all assays tested the xCELLigence System performed best on adult worms as the test was accurate, simple, required a minimal number of worms and offered the possibility for conducting a medium-throughput screening.

This study quantifies the rate and intensity of re-infection with human hookworm and Schistosoma mansoni infection 12 months following successful treatment, and investigates the influence of socio-economic, geographical and environmental factors. A longitudinal study of 642 individuals aged over 5 years was conducted in Minas Gerais State, Brazil from June 2004 to March 2006. Risk factors were assessed using interval censored regression for the rate and negative binomial regression for intensity. The crude rate and intensity of hookworm re-infection was 0·21 per year (95% confidence interval (CI) 0·15–0·29) and 70·9 epg (95% CI 47·2–106·6). For S. mansoni the rate was 0·06 per year (95% CI 0·03–0·10) and intensity 6·51 epg (95% CI 3·82–11·11). Rate and intensity of re-infection with hookworm were highest among males and positively associated with previous infection status, absence of a toilet and house structure. Rate and intensity of S. mansoni re-infection were associated with previous infection status as well as geographical, environmental and socio-economic factors. The implications of findings for the design of anti-helminth vaccine trials are discussed.

In 1994 and 2002, respectively, the World Health Organisation proposed that treatment for hookworm and schistosomiasis could be provided during pregnancy. It was hoped that this might have benefits for maternal anaemia, fetal growth and perinatal mortality; a beneficial effect on the infant response to immunisation was also hypothesised. Three trials have now been conducted. Two have examined the effects of benzimidazoles; one (the Entebbe Mother and Baby Study) the effects of albendazole and praziquantel. All three were conducted in settings of high prevalence but low intensity helminth infection. Results suggest that, in such settings and given adequate provision of haematinics, the benefit of routine anthelminthics during pregnancy for maternal anaemia may be small; none of the other expected benefits has yet been demonstrated. The Entebbe Mother and Baby Study found a significant adverse effect of albendazole on the incidence of infantile eczema in the whole study population, and of praziquantel on the incidence of eczema among infants of mothers with Schistosoma mansoni. Further studies are required in settings that differ in helminth species and infection intensities. Further research is required to determine whether increased rates of infantile eczema translate to long-term susceptibility to allergy, and to explore the underlying mechanisms of these effects. The risks and benefits of routine anthelminthic treatment in antenatal clinics may need to be reconsidered.

An attempt was made to identify the human hookworm involved in failed-treatment cases using abnormal hosts and scanning electron microscopy. Thirty-seven, 2 to 6 month old Chinese hamsters (Cricetulus griseus) from a closed, outbred, conventional colony, were each given between 20 and 120 filariform larvae per os. The larvae were cultured from faeces from mebendazole (Vermox®) 500 mg single-dose, failed-treatment cases living in the lowveld farming area of the Transvaal Province, South Africa. About 60 to 78 days after inoculation, the animals were killed and adult worms were removed from their small intestines. Eleven (30%) of the 37 hamsters harboured a total of 31 adult worms (19 males and 12 females), while 26 hamsters were refractory to infection. The greatest number of worms recovered from a single animal was six. A total of 27 worms (17 males and 10 females) were subjected to examination by scanning electron microscopy. Micrographs showed male and female worms to be morphologically all of the Necator americanus species, as identified by a pair of ventral and dorsal cutting plates, a dorsal tooth and the fused terminus of spicules in the male bursa. The transverse cuticular striations were distinct and smooth. Several points of interest arose from the results of this study and are discussed.

Of 756 dog faecal deposits collected from the road side and public places in five Jordanian Governorates 466 (61·6%) harboured parasite ova, oocysts and/or larvae. Of these, 67·7%, 26·8%, 4·1% and 1·4% revealed one, two, three and four different types of parasite ova, oocysts or larvae in the same sample, respectively. Examination of the infected samples revealed that 44·1% contained taeniid ova, 19·8% Dipylidium caninum, 19% Toxocara canis, 8% Sarcocystis spp. oocysts, 5% hookworm larvae, 1·5% Diphyllobothrium latum, 0·1% Capillaria spp. and 0·1% Trichuris vulpis eggs.

Reinfection with hookworm (Necator americanus) following chemotherapy was studied over 2 years in a rural village in Madang Province, Papua New Guinea. The prevalence of hookworm infection had returned to pre-treatment levels after 2 years, and the geometric mean hookworm burden had returned to 58 % of the pre-treatment value. The rate of acquisition of adult worms was independent of host age, and was estimated as a geometric mean of 2·9–3·3 worms/host/year (arithmetic mean 7·9–8·9 worms/host/year). There was significant predisposition to hookworm infection; the strength of this predisposition did not vary significantly between age or sex classes.

An epidemiological survey of intestinal helminthiases was conducted on 766 primary school children aged 5–16 years from Ile-Ife, Nigeria. On the basis of stool examinations, the prevalence of Ascaris lumbricoides, Trichuris trichiura, hookworm and Strongyloides stercoralis was 88·5, 84·5, 33·1 and 3% respectively. Intensity of infection was measured indirectly by egg counts for each species of helminth and also by counting worms passed after chemotherapy in the case of A. lumbricoides. The influence of host age and sex on infection levels was assessed. Relationships between the intensities of A. lumbricoides, T. trichiura and hookworm in individual children were identified. After anthelmintic treatment with levamisole, the frequency distribution of A. lumbricoides per host and the relationship between parasite fecundity and worm burden were investigated.