Intensity Of Helminth Infections Research Articles

Hookworm, Ascaris lumbricoides infection and polyparasitism associated with poor cognitive performance in Brazilian schoolchildren

To investigate the relationship between hookworm and Ascaris lumbricoides infection and performance on three subsets of the Wechsler Intelligence Scale for Children - third edition (WISC-III) (Digit Span, Arithmetic and Coding) and Raven Colored Progressive Matrices. Cross-sectional study of 210 children between the ages of 6 and 11 years in Americaninhas, Minas Gerais, Brazil. Separate proportional odds models were used to measure the association between the intensity of helminth infections and poor performance on each of the four cognitive tests. After adjusting for sex, age, socioeconomic status and other helminth infections, moderate-to-high-intensity hookworm infection was associated with poor performance on the WISC-III Coding subtest [OR = 3.20; 95% confidence interval (CI) = 1.43-7.17], low intensity of hookworm infection was associated with poor performance on the WISC-III Coding subtest [odds ratio (OR) = 3.71; 95% CI = 1.80-7.66] and moderate-to-high-intensity A. lumbricoides infection was associated with poor performance on the Raven test (OR = 2.03; 95% CI = 1.04-3.99), all in comparison with uninfected children. Children co-infected with A. lumbricoides infection and hookworm infection had greater odds of poor performance on some WISC-III subtests than children with only A. lumbricoides infection. These findings suggest that hookworm infection may be associated with poorer concentration and information processing skills, as measured on the WISC-III Coding subtest, and that A. lumbricoides infection may be associated with poorer general intelligence, as measured through the Raven Colored Progressive Matrices. This study also presents evidence that polyparasitized children experience worse cognitive outcomes than children with only one helminth infection.

Immune responses during helminth-malaria co-infection: a pilot study in Ghanaian school children

Malaria and helminth infections have a shared geographical distribution and therefore co-infections are frequent in tropical areas of the world. Human populations of helminth and malaria co-infection have shown contradictory results for the course of malarial infection and disease, possibly depending on the type of helminth studied, the intensity of helminth infection and the age of the study population. Although immunological studies might clarify the underlying mechanisms of protection or increased susceptibility, there are very few studies that have looked at immunological parameters in helminth and malaria co-infection. After discussing the available immunological data on co-infection, we describe a pilot study performed in Ghanaian school children where we compare anti-malarial responses in children living in an urban area, where the prevalence of helminth and Plasmodium falciparum infections was low, with that of children living in a rural area with high prevalence of helminth and Plasmodium falciparum infections.

Protective effect of Schistosoma mansoni infection on allergic airway inflammation depends on the intensity and chronicity of infection

Population studies have suggested that chronic and intense helminth infections, in contrast to acute and mild helminth infections, might suppress allergic airway inflammation. We sought to address the question of how the chronicity and intensity of helminth infections affect allergic airway inflammation in a well-defined experimental model. C57/Bl6 mice were infected with Schistosoma mansoni, followed by sensitization and challenge with ovalbumin (OVA), and different stages and intensities of infection were studied. To this end, mice were analyzed at 8, 12, or 16 weeks, representing the acute, intermediate, or chronic phases of infection, respectively. Lung lavage eosinophilia, peribronchial inflammation, and OVA-induced airway hyperresponsiveness were increased during acute infection but significantly decreased when infection progressed into chronicity. Decreases in lung lavage eosinophilia were parasite density-dependent. Similar levels of OVA-specific IgE were found during all phases of infection, whereas both OVA-specific and parasite-specific T(H)2 cytokine levels were significantly reduced during chronic infection. Inhibition of airway inflammation could be transferred to OVA-sensitized recipient mice by B cells and CD4(+) T cells from spleens of chronically, but not acutely, infected mice. This suppression was IL-10-dependent. During chronic, but not acute, helminth infections, suppressive mechanisms are induced that regulate immune reactions to inhaled allergens. These data confirm human epidemiologic observations in a well-controlled animal model. Characterization of chronic helminth infection-induced regulatory mechanisms will help in the development of future therapeutics to treat or prevent allergic disease.

Associations between mild-to-moderate anaemia in pregnancy and helminth, malaria and HIV infection in Entebbe, Uganda

SummaryIt is suggested that helminths, particularly hookworm and schistosomiasis, may be important causes of anaemia in pregnancy. We assessed the associations between mild-to-moderate anaemia (haemoglobin >8.0 g/dl and <11.2 g/dl) and helminths, malaria and HIV among 2507 otherwise healthy pregnant women at enrolment to a trial of deworming in pregnancy in Entebbe, Uganda. The prevalence of anaemia was 39.7%. The prevalence of hookworm was 44.5%, Mansonella perstans 21.3%, Schistosoma mansoni 18.3%, Strongyloides 12.3%, Trichuris 9.1%, Ascaris 2.3%, asymptomatic Plasmodium falciparum parasitaemia 10.9% and HIV 11.9%. Anaemia showed little association with the presence of any helminth, but showed a strong association with malaria (adjusted odds ratio (AOR) 3.22, 95% CI 2.43–4.26) and HIV (AOR 2.46, 95% CI 1.90–3.19). There was a weak association between anaemia and increasing hookworm infection intensity. Thus, although highly prevalent, helminths showed little association with mild-to-moderate anaemia in this population, but HIV and malaria both showed a strong association. This result may relate to relatively good nutrition and low helminth infection intensity. These findings are pertinent to estimating the disease burden of helminths and other infections in pregnancy. [Clinical Trial No. ISRCTN32849447]

Immunocompetence and helminth community of the white-toothed shrew, Crocidura russula from the Montseny Natural Park, Spain

Host immunocompetence assessed by spleen size and response to phytohaemagglutinin (PHA) injection may give some indications on the control of parasite infection and on host mediation effect, through immunity, on parasite community structure. We investigated the helminth community and immunocompetence of the white-toothed shrew in a small area to test the relationship between immunocompetence and intensity of helminth infection. At the proximate level and if spleen mass and PHA response reflect the level of immunocompetence, we expected that individuals with a large spleen or a high PHA response should harbour a lower parasite load than individuals with relatively small spleen or low PHA response. In addition, we predicted that the structure of the helminth community should be mediated by the host’s immune defence. Spleen mass was linked to helminth infection. Nematodes and cestodes were negatively associated within hosts. PHA response was not related to total helminth intensity of infection but was negatively related to cestode intensity and positively to nematode intensity. This result suggests either a differential modulating effect on immunity by the two groups of worms or the existence of an antagonistic association between nematodes and cestodes mediated by the immune response of the host.

Safety of anti‐immunoglobulin E therapy with omalizumab in allergic patients at risk of geohelminth infection

BackgroundAlthough the role of immunoglobulin E (IgE) in immunity against helminth parasites is unclear, there is concern that therapeutic antibodies that neutralize IgE (anti-IgE) may be unsafe in subjects at risk of helminth infection.ObjectiveWe conducted an exploratory study to investigate the safety of omalizumab (anti-IgE) in subjects with allergic asthma and/or perennial allergic rhinitis at high risk of intestinal helminth infection. The primary safety outcome was risk of infections with intestinal helminths during anti-IgE therapy.MethodsA randomized, double-blind, placebo-controlled trial was conducted in 137 subjects (12–30 years) at high risk of geohelminth infection. All subjects received pre-study anthelmintic treatment, followed by 52 weeks' treatment with omalizumab or placebo.ResultsOf the omalizumab subjects 50% (34/68) experienced at least one intestinal geohelminth infection compared with 41% (28/69) of placebo subjects [odds ratio (OR) 1.47, 95% confidence interval (CI) 0.74–2.95, one-sided P = 0.14; OR (adjusted for study visit, baseline infection status, gender and age) 2.2 (0.94–5.15); one-sided P = 0.035], providing some evidence for a potential increased incidence of geohelminth infection in subjects receiving omalizumab. Omalizumab therapy was well tolerated, and did not appear to be associated with increased morbidity attributable to intestinal helminths as assessed by clinical and laboratory adverse events, maximal helminth infection intensities and additional anthelmintic requirements. Time to first infection (OR 1.30, 95% CI 0.79–2.15, one-sided P = 0.15) was similar between treatment groups. Infection severity and response to anthelmintics appeared to be unaffected by omalizumab therapy.ConclusionsIn this exploratory study of allergic subjects at high risk of helminth infections, omalizumab therapy appeared to be safe and well tolerated, but may be associated with a modest increase in the incidence of geohelminth infection.

Breeding status, contaminant burden and helminth parasites of Northern FulmarsFulmarus glacialisfrom the Canadian high Arctic

We studied the relationship between contaminant concentrations in livers, endohelminth prevalence and physiological indices of chronic stress (spleen size, heterophil/lymphocyte ratios) in Northern FulmarsFulmarus glacialiscollected during the breeding season in Nunavut, Canada. No blood parasites were found, similar to reports for other petrel species elsewhere. However, 54% of Fulmars had gastrointestinal helminths, principally cestodes (52% prevalence, mean intensity of 11 worms), nematodes (34% prevalence, 3.6 worms) and acanthocephalans (3%, eight worms). Both prevalence and intensity of helminth infections were lower for Arctic Fulmars than for Fulmars and other petrels found in southern parts of the species’ range. Spleen size was not significantly related to either contaminant concentration or presence of parasites, suggesting that Fulmar health was generally unaffected by contaminant and parasite levels at the colony. However, we cannot rule out the possibility that Fulmars with higher parasitaemias or contaminant loads were in poorer condition and did not attend the breeding colony.

Distribution of gastrointestinal helminths in chicken farms in the Gharb region—Morocco

Gastrointestinal tracts of 300 chickens from three villages of the Gharb region, Morocco, were examined for adult helminths during 2002-2005. Helminth species found were: Notocotylus gallinarum (prevalence 0.7%), Hymenolepis carioca (3.7%), Raillietina echinobothrida (5.7%), Hymenolepis contaniana (7%), Raillietina tretragona (9.3%), Raillietina cesticillus (12%), Capillaria obsignata (6%), Subulura brumpti (15.3%), Heterakis gallinarum (10%), Cheilospirura hamulosa (2.7%), Dispharynx nasuta (5.3%), Ascaridia galli (9%), and Tetrameres sp. (3.3%). The prevalence and mean intensity of helminth infections did not differ significantly between male and female chickens.

Effect of age, sex and season on the prevalence and intensity of helminth infections in domestic pigeons (Columba livia) from Bursa Province, Turkey

The one-year study reported in this paper was carried out from April 2002 to March 2003 in domestic pigeons (Columba livia) of Bursa Province (Turkey) to determine the occurrence of helminth species and to evaluate the effect of host age, sex and season on their prevalence and intensity. A total of 100 (31 young and 69 adult) domestic pigeons were necropsied and examined. The results of necropsies revealed that 74 pigeons harboured helminth infections. Three helminth species were identified: Baruscapillaria obsignata (63%), Ascaridia columbae (42%) and Raillietina echinobothrida (1%). There were no significant differences in the prevalence of B. obsignata and A. columbae by host age and sex. Significantly the highest prevalence rate of A. columbae was observed in the autumn months, but there was no significant difference in the seasonal prevalence of B. obsignata. The mean intensity of B. obsignata and A. columbae was higher in adults than in young pigeons but it did not differ significantly between the two sexes. The highest mean intensity rate of B. obsignata was observed in the autumn, while there was no significant difference for A. columbae with regard to season. From the data obtained in this study it can be concluded that in regions with similar climatic conditions as those in the present study area, pigeon breeders should be cautioned especially of B. obsignata and A. columbae infections of adult pigeons in the autumn months.

Parasitological aspects and biochemical changes of infected cultured tilapia (Oreochromis hybrid)

Background. Fish farming has been developed due to decline of traditional fishing where tilapia culture is one of the principal sources for fish production. This study was aimed to investigate the prevalence and impact of helminth infection on the health of cultured hybrid tilapia, Oreochromis sp.Materials and methods. Prevalence and intensity of helminth infection and histopathological response of infected organs were studied. Changes of biochemical composition, and protein electrophoritic pattern, and heavy metals levels of liver and muscle tissues were determined.Results. Helminth infection was restricted to the liver of 60% of the examined fish. Of this number 33% were infected by undifferentiated nematode larvae and heterophyid metacercariae while 67% showed the metacercarial infection only. Infection caused a noticeable alternation in histological architecture of the liver that was accompanied by depletion in hepatic glycogen, total lipids, and total protein. Moreover, biochemical components of the muscle tissues were significantly decreased along with intensity of infection. Protein fractions of the liver and muscle tissues were highly variable. Intensity of the parasitic infection was directly correlated with Fe and Mn levels in both liver and muscle.Conclusion. s. Cultured fish also suffered from helminth infection that significantly impaired the health and condition of fish as shown by histopathological, biochemical, and protein fractions changes recorded in this study. In additions, intensity of helminth infection might increase the capacity of infected organs in accumulation of heavy metals.

Local variation in helminth burdens of bank voles (Clethrionomys glareolus) from ecologically similar sites: temporal stability and relationships with hormone concentrations and social behaviour.

Populations of bank voles (Clethrionomys glareolus) in a fragmented forest habitat in north-east Poland showed local differences in helminth infection intensity, morphometric measures and organ weights that were consistent with differences at the same locations two years previously. Although overall intensities of infection were lower than previously, and there were some differences in the relative intensities of individual helminth species, site differences remained significant and were consistent across replicated subsites. In keeping with site differences in helminth infection and adrenal gland weight and asymmetry, voles at site 1 (high intensity infection) had higher circulating concentrations of corticosterone than those at site 2 (low intensity infection). Since males were sampled outside the breeding season, and thus non-scrotal, testosterone levels were low and did not differ between sites. As previously, voles at site 1 also showed greater hind foot asymmetry. Dyadic interactions between males from the same and different sites in the laboratory showed that males from site 1 were significantly less aggressive, especially when confronted with intruder males from site 2. There was no relationship between aggressiveness and intensity of infection overall or at site 1, but a significant negative relationship emerged at site 2. Aggression thus appeared to be downregulated at the higher intensity site independently of individual levels of infection. Terminal corticosterone concentrations were greater at site 1 and lower among residents that initiated more aggression. While corticosterone concentrations rose over the period of testing, they did not correlate with the amount of aggression initiated or received.

Helminths of goats in Mongolia

Post-mortem examinations of 236 goats from all provinces in Mongolia were performed for the study of helminths in goats. Thirty-nine helminth species belonging to three classes, 14 families and 23 genera were found. Trichocephalus spiralis and Avitellina centripunctata are reported for the first time in goats in Mongolia. The prevalence and intensity of helminth infections are reported for three age groups of goats in four seasons and three geographic zones in Mongolia. Common helminth infections of goats in all zones of Mongolia were infections of Ostertagia, Marshallagia and Nematodirus. In addition, fecal samples of 15 kids, 15 yearlings and 15 adult goats were examined monthly for eggs. The highest number of eggs per gram (EPG) of feces was counted in March (average 1335.3±405.3) and the lowest count was in November (54±18.6).

Epidemiology of soil‐transmitted nematode infections in Ha Nam Province, Vietnam

Baseline epidemiological data are presented from a parasitological survey conducted in Thuy Loi commune, Ha Nam province, Vietnam; a farming community where night soil is routinely used as fertilizer for crops. 177 households were visited and 543 individuals (aged 1-88 years) recruited to the study. Helminth infection intensity was assessed by Kato-Katz to determine the density of parasite eggs per gram of stool (epg). Ascaris lumbricoides, Trichuris trichiura and hookworm infections were the only species detected. 83% of individuals were infected with A. lumbricoides (mean epg = 11,971), 94% with T. trichiura (mean epg = 793) and 59% with hookworm (mean epg = 302). Age-dependent patterns of infection prevalence and intensity were similar for A. lumbricoides and T. trichiura, but markedly different for hookworm infection. Similarly, age-dependency in the k-values for the three infections was due to covariance with the respective mean intensities with age rather than to independent age effects, with similar patterns for A. lumbricoides and T. trichiura, and a different pattern for hookworm. Three major conclusions can be drawn from the multiple-species analyses: There is positive interaction between A. lumbricoides and T. trichiura infections; high-intensity A. lumbricoides infections are significantly associated with high-intensity T. trichiura infections; and there is positive interaction between these two species such that infection intensity of A. lumbricoides is higher in individuals with concurrent T. trichiura infection than in individuals without and vice versa.

Hemoquant determination of hookworm-related blood loss and its role in iron deficiency in African children.

Iron deficiency remains the most prevalent form of human malnutrition, and current interventions to control it have not decreased the global prevalence. Hookworm control activities are becoming more widely implemented, but the importance of these efforts to prevent anemia in populations is not well-defined. We studied the relationships among hookworm infection, intestinal blood loss, and iron status of 203 Zanzibari school children. Helminth infection intensity was quantified by fecal egg counts, and iron deficiency anemia was defined by low hemoglobin and serum ferritin concentrations. Intestinal blood loss was quantified by measuring fecal heme and heme breakdown products as porphyrin, a noninvasive method that has not been used previously to assess hookworm blood loss. Intestinal blood loss was strongly and linearly related to hookworm egg counts. The degree of degradation of fecal heme indicated that blood loss occurred in the upper gastrointestinal tract, compatible with the behavior of hookworms. Trichuris trichiura and Ascaris lumbricoides infections were also common, but did not contribute significantly to intestinal blood loss in this population. The prevalence of iron deficiency anemia increased steadily as hookworm infection intensity and intestinal blood loss increased. In the context of a poor diet, as exists in Zanzibar and many tropical countries, hookworm-related blood loss contributes dramatically to anemia. In such contexts, hookworm control is a feasible and essential component of anemia control. Determination of fecal heme is relatively simple and noninvasive and may be a useful tool for measuring the impact of hookworm control activities.

Compliance and absenteeism in school children: implications for helminth control

The validity of epidemiological surveys and the success of helminth control programmes based on the diagnosis of infection depend upon an accurate screening procedure. The success of all school-based control programmes, whether they involve prior diagnosis or not, depends on the level of school attendance and school enrolment. The degree to which compliance and school absenteeism may affect estimates of helminth infection and the coverage of treatment was investigated using empirical data from a survey conducted in 3 rural schools in Jamaica. Two sequential stool samples were requested from each child aged 9 to 12 years and screened for the presence and intensity of helminth infection using the Kato thick smear technique. Of the 696 children recruited into the study, 94% agreed to participate but only 90% of these children actually provided a stool sample for diagnosis and only 74% returned the second stool. Children infected with moderate to heavy loads of Trichuris trichiura were less likely to comply fully with the protocol than the uninfected children. They also took longer to comply and were absent from school more often than their uninfected counterparts. Increasing the sampling effort increased the compliance of all infected, and heavily infected, children. By giving them the option to comply, heavily infected children were under-represented by the sampling procedure. This has important implications for the design of control programmes and epidemiological surveys.

Helminths of the Florida Manatee, Trichechus manatus latirostris, with a Discussion and Summary of the Parasites of Sirenians

We examined 215 Florida manatees (Trichechus manatus latirostris) at necropsy to determine the helminth fauna. Six species were identified: Heterocheilus tunicatus (Nematoda: Ascaridoidea); Anoplocephala sp. (Cestoda: Cyclophyllidea); and 4 species of trematodes, Cochleotrema cochleotrema (Digenea: Opisthotrematidae), Chiorchis fabaceus (Digenea: Paramphistomatidae), Nudacotyle undicola (Digenea: Nudacotylidae), and Moniligerum blairi (Digenea: Opisthotrematidae). Seventy-three percent of the manatees examined were infected with at least 1 species of helminth. The mean number of species of helminths per infected manatee was 1.9 with a range of 1-4. Fifty-nine manatees were helminth-free; 30 of these were calves. No associations were found between the intensity of helminth infections and host sex, age class, season, and geographic location of recovery, or cause of death. Differences in parasite prevalence between age classes were highly significant for Chiorchis, Cochleotrema, and Heterocheilus, due to a low number of infected calves. A higher prevalence of Cochleotrema was found in manatees recovered from eastern Florida, and Heterocheilus was evident in significantly more manatees from western and souther Florida. Comparisons in the parasite fauna are made among Florida manatees and other sirenian populations, and a brief review of sirenian parasites is included.

Prevalence and Intensity of Helminth Infections in Southwest Puerto Rico

The present study reveals that in Puerto Rico, despite the general rise in the standard of living, infection with intestinal parasites is still a major human health problem, especially in the younger school age population. Surveys conducted in the past have shown that the highest rates of infection with Ascaris lumbricoides and Trichuris trichiura occur in elementary school children (Maldonado, 1967, Boletin de la Asociaci6n Medica de Puerto Rico 59: 339-352; Greenberg and Ferguson, 1971, Boletin de la Asociaci6n Medica de Puerto Rico 63: 208-211). The last survey by Greenberg and Ferguson of a group of 6,086 first graders from 18 municipalities in Puerto Rico revealed a high prevalence of T. trichiura (75%), A. lumbricoides (13%) and hookworm (12%). A community-based study by Knight et al. (1973, Boletin de la Asociaci6n Medica de Puerto Rico 65: 205-207) revealed that in 1,000 inhabitants the prevalence of T. trichiura was 56% and the prevalence of Entamoeba coli was 11 %. Also, the prevalence of infection with other parasites like A. lumbricoides, Strongyloides stercoralis and Balantidium coli was less than 2%. In the western part of the island, Weller and Dammin (1945, Puerto Rico Journal of Public Health and Tropical Medicine 21: 125-147) reported a high prevalence of schistosomiasis in the towns of Anasco (25%) and Mayaguez (11%). Since that time, no study has been done to evaluate the parasitologic status of the population in the western region. The study population consisted of 852 children (423 males and 429 females) aged 8 to 12 years from 9 rural elementary schools located in 7 towns of southwest Puerto Rico. Single fecal specimens were collected in 1.0-ounce tin boxes and examined in duplicate by the Kato cellophane thick smear technique (Komiya and Kobayashi, 1966, Japanese Journal of Medical Science and Biology 19: 59-64). All parasite eggs and larvae seen by light microscopy at low magnification were counted and the results expressed in eggs per gram of feces (epg), multiplying by 24 the mean of the total number of eggs found. St tistical analysis consisted of chi-square test and Spearman's rank correlation. Five distinct parasitic infections were recorded. Trichuris trichiura was the most prevalent with 13%, followed by A. lumbricoides with 3%. The prevalences of hookworm and S. stercoralis were less than 1%. Enterobius vermicularis eggs were found in the feces of 2 individuals; however, since the diagnosis of this parasite is performed by the examination of perianal swabs, these results undoubtedly were under representative. As shown in Figure 1, the towns with the highest prevalence of Trichuris were Maricao (42%), Anasco (31 %) and Mayaguez (19%). Ascaris also was highly prevalent (Maricao 11%, Anasco 15% and Mayaguez 5%), but not recorded in the other 4 towns. Also found in these 3 towns were 18 cases (17%) of Ascaris-Trichuris combined infections. This great geographical variation in the distribution of parasites in Puerto Rico has been doc-