The clinical significance of gastrointestinal helminths--a review

Helminths of captive and free-ranging populations of the mountain gazelle (Gazella gazella): Evidence from faecal examination

BACKGROUND

Understanding parasite diversity in wild and captive animal populations has critical implications for both individual animal health and ecosystem dynamics in a broader sense. In mountain gazelles (Gazella gazella), the gastrointestinal helminth community is poorly understood, limiting our efforts in the conservation of this endangered bovid species. This species has only two remaining populations in the world, including the isolated northernmost population in Türkiye.

OBJECTIVES

To identify and compare the diversity and prevalence of gastrointestinal helminths in captive and free-ranging populations of mountain gazelles in Hatay, Türkiye, and to assess potential zoonotic risks.

METHODS

In total, 105 fresh faecal samples, 45 individual samples and 60 faecal samples, representing 16 pools, from both captive and free-ranging populations were collected and analysed using Fulleborn flotation, Benedek sedimentation and Bearman-Wetzel methods faecal flotation methods, including the McMaster technique to determine the severity of infection.

RESULTS

We detected 12 helminth taxa in our examination of faecal samples, including gastrointestinal nematodes, lungworms and trematodes. Parasites from the Trichostrongyloidea family demonstrated variable hatching stages and rates, potentially influenced by ambient conditions. We also detected one protozoan among the samples. Our results revealed a higher diversity of parasites in free-ranging populations compared to captive ones.

CONCLUSIONS

This study underscores the necessity for regular parasitological surveillance in both captive and free-ranging wildlife populations for effective conservation management. It also contributes to the 'One Health' perspective by highlighting the potential zoonotic risks posed by parasites in wild ruminants. Our results have implications for the conservation and management of the mountain gazelle.

Evolutionary perspectives on substance and behavioural addictions: Distinct and shared pathways to understanding, prediction and prevention

Addiction poses significant social, health, and criminal issues. Its moderate heritability and early-life impact, affecting reproductive success, poses an evolutionary paradox: why are humans predisposed to addictive behaviours? This paper reviews biological and psychological mechanisms of substance and behavioural addictions, exploring evolutionary explanations for the origin and function of relevant systems. Ancestrally, addiction-related systems promoted fitness through reward-seeking, and possibly self-medication. Today, psychoactive substances disrupt these systems, leading individuals to neglect essential life goals for immediate satisfaction. Behavioural addictions (e.g. video games, social media) often emulate ancestrally beneficial behaviours, making them appealing yet often irrelevant to contemporary success. Evolutionary insights have implications for how addiction is criminalised and stigmatised, propose novel avenues for interventions, anticipate new sources of addiction from emerging technologies such as AI. The emerging potential of glucagon-like peptide 1 (GLP-1) agonists targeting obesity suggest the satiation system may be a natural counter to overactivation of the reward system.

Development of Immunochromatographic Test Kit for Rapid Detection of Specific IgG4 Antibody in Whole-Blood Samples for Diagnosis of Human Gnathostomiasis

Human gnathostomiasis is a harmful food-borne zoonosis caused by roundworms of the genus Gnathostoma. The parasite can occasionally migrate to the central nervous system, causing life-threatening disease and death. Here, we report a new point-of-care (POC) test kit, the gnathostomiasis blood immunochromatographic test (GB-ICT) kit. The kit is based on recombinant Gnathostoma spinigerum antigen and detects specific IgG4 antibody in whole-blood samples (WBSs). The GB-ICT kit showed potentially high diagnostic values with simulated WBSs (n = 248), which were obtained by spiking patients’ sera with red blood cells. The accuracy, sensitivity, specificity, and positive and negative predictive values were 95.2%, 100%, 93.8%, 81.5%, and 100%, respectively. Ten WBSs from clinically suspected gnathostomiasis patients were all positive according to the GB-ICT kit, while 10 WBSs from healthy volunteers were negative. The GB-ICT kit is a simple and convenient POC testing tool using finger-prick blood samples: venous blood sampling and serum separation processes are not required. The GB-ICT kit can support clinical diagnosis in remote areas and field settings without sophisticated equipment facilities.

Assessment of oxidative/nitrosative stress biomarkers and DNA damage in Teladorsagia circumcincta following exposure to zinc oxide nanoparticles

Drug resistance to helminth parasites is one of the most serious problems to threaten the livestock industry. The problem also poses a major threat to public health. Therefore, novel and safe agents should urgently be investigated to control parasitic infections. The current study was conducted to evaluate the possible antiparasitic effects of zinc oxide nanoparticles (ZnO-NPs) on one of the most prevalent gastrointestinal nematodes, Teladorsagia circumcincta. The worms were incubated with various concentrations of ZnO-NPs: 1, 4, 8, 12 and 16 ppm for 24 hours. Mobility and mortality of the parasites were recorded at four-hour intervals. At the endpoint, several biomarkers of oxidative/nitrosative stress, including superoxide dismutase, glutathione peroxidase and catalase, as well as lipid peroxidation, protein carbonylation, total antioxidant status, nitric oxide contents and DNA damage, were measured in the homogenized samples. ZnO-NPs showed significant anthelminthic effects, depending on time and concentration. Furthermore, the nanoparticle induced severe oxidative/nitrosative stress and DNA damage. ZnO-NPs could be considered as a novel and potent anthelminthic agent.

Infectious causes of appendicitis

The pathologic spectrum of the inflamed appendix encompasses a wide range of infectious entities, some with specific histologic findings, and others with nonspecific findings that may require an extensive diagnostic evaluation. The appendix is exclusively involved in some of these disorders, and in others may be involved through extension from other areas of the gastrointestinal tract. This review discusses the pathologic features of bacterial, viral, fungal, and parasitic infections affecting the appendix, including adenovirus; cytomegalovirus; Yersinia, Actinomyces, Mycobacterium, or Histoplasma species; Enterobius vermicularis; schistosomiasis; and Strongyloides stercoralis. Pertinent ancillary diagnostic techniques and the clinical context and significance of the various infections are also discussed.

Human gastrointestinal nematode infections: are new control methods required?

Gastrointestinal (GI) nematode infections affect 50% of the human population worldwide, and cause great morbidity as well as hundreds of thousands of deaths. Despite modern medical practices, the proportion of the population infected with GI nematodes is not falling. This is due to a number of factors, the most important being the lack of good healthcare, sanitation and health education in many developing countries. A relatively new problem is the development of resistance to the small number of drugs available to treat GI nematode infections. Here we review the most important parasitic GI nematodes and the methods available to control them. In addition, we discuss the current status of new anthelmintic treatments, particularly the plant cysteine proteinases from various sources of latex-bearing plants and fruits.

Appendicitis and infections of the appendix

The pathologic spectrum of the acutely inflamed appendix encompasses a wide range of infectious and noninfectious entities. The appendix suffers alone in some of these disorders, and in others may be involved through extension from other areas of the gastrointestinal tract. Although the appendix is the most commonly resected and examined intraabdominal organ, the pathogenesis and etiology of acute nonspecific appendicitis (the most common diagnosis made in this organ) remains enigmatic. This review encompasses the pathology, pathogenesis, and bacteriology of acute appendicitis, as well as controversial issues such as the diagnosis of chronic appendicitis and the significance of a morphologically unremarkable appendectomy specimen in the clinical context of appendicitis. In addition, the pathologic features, pertinent diagnostic techniques, and clinical significance of several specific bacterial, viral, fungal, and parasitic infections affecting the appendix are presented, including adenovirus, cytomegalovirus, Yersinia species, actinomycosis, Mycobacteria species, histoplasmosis, pinworms, schistosomiasis, and Strongyloides stercoralis.

Definition of genetic markers in nuclear ribosomal DNA for a neglected parasite of primates, Ternidens deminutus (Nematoda: Strongylida) – diagnostic and epidemiological implications

Ternidens deminutus (Strongylida) is a parasitic nematode infecting non-human and human primates in parts of Africa, Asia and the Pacific islands. The present study genetically characterized T. deminutus and defined genetic markers in nuclear ribosomal DNA (rDNA) as a basis for developing molecular-diagnostic tools. The sequences of the second internal transcribed spacer (ITS-2) of rDNA were determined for adult specimens of T. deminutus (Nematoda: Strongylida: Oesophagostominae) from the Olive baboon and the Mona monkey. The length and G+C content of the ITS-2 sequences was 216 bp and approximately 43%, respectively. While there was no sequence variation among individual T. deminutus specimens from the baboon, 6 (2.8%) nucleotide differences were detected in the ITS-2 between the parasite from baboon and that of the Mona monkey, which is similar to the difference (3.2%) between 2 other species of Oesophagostominae (Oesophagostomum bifurcum and O. stephanostomum) from non-human primates, suggesting significant population variation or the existence of cryptic (i.e. hidden) species within T. deminutus . Pairwise comparisons of the ITS-2 sequences of the 2 operational taxonomic units of T. deminutus with previously published ITS-2 sequences for selected members of the subfamilies Oesophagostominae and Chabertiinae indicated that species from primates (including those representing the subgenera Conoweberia and Ihleia) are closely related, in accordance with previous morphological studies. The sequence differences (27-48.3%) in the ITS-2 between the 2 taxonomic units of T. deminutus and hookworms (superfamily Ancylostomatoidea) enabled their identification and delineation by polymerase chain reaction (PCR)-based mutation scanning. The genetic markers in the ITS-2 provide a foundation for improved, PCR-based diagnosis of T. deminutus infections and for investigating the life-cycle, transmission patterns and ecology of this parasite.

Screening for intestinal parasites in recently arrived children from East Africa

BACKGROUND

Intestinal parasitic carriage is common in East African populations with a wide spectrum of clinical severity. There are scant data on the rates of carriage in East African immigrants to Australia. This study describes the prevalence of and risk factors for intestinal parasite carriage among children recently arrived from East African countries.

METHODS

Children aged 0-17 years, who attended an outpatient clinic, were born in East Africa and had immigrated since 1998 were eligible to participate. A single preserved stool specimen was collected for faecal microscopy, and blood tests were conducted for Strongyloides and Schistosoma serology, full blood examination and serum ferritin.

RESULTS

One hundred and thirty-five children (median age 8.1 years, range 1.0-17.5) participated, of whom 133 (99%) provided a stool specimen. Parasites were detected in 50% of samples, and 18% of children carried a possibly pathogenic species. No child was symptomatic at diagnosis. Positive or equivocal serology occurred in 11% of children for Strongyloides and 2% for Schistosoma. Anaemia and iron deficiency were detected in 16% of all children. Those carrying an intestinal parasite were older (mean age 9.8 vs 7.4 years, P= 0.002) and less likely to be anaemic (odds ratio 0.37, 95% confidence interval 0.14-0.96) than those who were not carriers.

CONCLUSIONS

Carriage of intestinal parasites is common among children from East Africa. Those carrying pathogenic organisms require treatment and follow up to ensure eradication. The results of this survey support the need for routine assessment of newly arrived immigrants from East Africa for intestinal parasites, anaemia and iron deficiency.

Ascariasis in the subdistrict of Cavacos, municipality of alterosa (MG), Brazil: effect of mass treatment with albendazole on the intensity of infection

The clinical and epidemiologic aspects of infection with Ascaris lumbricoides were studied in a random stratified sample of the population of the subdistrict of Cavacos, municipality of Alterosa (Minas Gerais, Brazil). The effect of mass treatment with a single dose of albendazole on the prevalence and intensity of infection was also studied six months later in the same population. During the first phase of the study, a questionnaire was applied to 248 individuals to obtain information about the socioeconomic, sanitary and clinical conditions of the population surveyed. A total of 230 fecal samples were also examined by the Kato-Katz technique in order to determine the intensity of A. lumbricoides infection. Two hundred and two individuals were simultaneously submitted to blood counts and 70 children aged 12 years or less were evaluated for nutritional status. The presence of A. lumbricoides and other helminth eggs was also determined in 22 soil samples collected in the urban zone of Cavacos. Infection with enteroparasitic helminths was detected in 29.1% of the sample, with a predominance of A. lumbricoides (23.9%). Parasitism and/or intensity of A. lumbricoides infection were significantly correlated with age range (15 years or less), social class, sanitary and living conditions (water, sewage and domiciliary area per person), and presence of abdominal pain. However, these parameters were not correlated with nutritional status or hematocrit levels. During the second phase of the study, a slight but not statistically significant decrease in the prevalence of A. lumbricoides infection was detected after treatment with albendazole. However, an important and significant reduction in the amount of A. lumbricoides eggs eliminated through the feces was detected, indicating that the intensity of A. lumbricoides infection was lower in all the age ranges of the Cavacos population, especially among younger individuals, even six months after administration of the anthelminthic agent.

Intestinal parasites in refugees and asylum seekers entering the Stockholm area, 1987-88: evaluation of routine stool screening

In order to evaluate the results of routine screening for intestinal parasites, the medical records of 4592 refugees and asylum seekers arriving in the Stockholm area from January 1987 to December 1988 were reviewed. 3938/4592 (86%) delivered stool specimens for examination and intestinal parasites were demonstrated in 651/3938 (17%). Protozoa, mainly Giardia intestinalis, were found in 403/3938 (10%) and helminths, mainly nematodes, in 277/3938 (7%). Intestinal parasites were most frequently recovered in subjects coming from the Indian subcontinent/Southeast Asia and Africa (infection rates 39% and 25%, respectively). Extensive variations in the prevalence of intestinal parasite infection in various ethnic groups (range 4%-39%) were largely attributable to variations in prevalence of helminthic infections (range 2%-34%). Origin from the tropics or subtropics as well as low age, male sex, rural region of domicile before/during exile and short length of stay in Sweden were related to intestinal parasitic infection. Lack of data on morbidity in untreated asymptomatic carriers, limited risks for transmission of the recovered parasites in Sweden as well as the expenses for screening indicate a need for reconsideration of the present praxis of mass screening in favour of a selective screening of high-risk groups based on country of origin and age.

Gastroenterological emergencies in the tropics

Significant differences exist in the prevalence of most gastroenterological emergencies in tropical compared with temperate countries. Both ethnic and environmental (often clearly defined geographically) factors are relevant. The major oesophageal lesions which can present acutely in tropical countries are varices and carcinoma; bleeding and obstruction are important sequelae. Peptic ulcer disease (and its complications), often associated (not necessarily causally) with Helicobacter pylori infection, has marked geographical variations in incidence. Emergencies involving the small intestine are dominated by severe dehydration, and its sequelae, resulting from secretory diarrhoea, most notably cholera. However, enteritis necroticans ('pig bel' disease), paralytic ileus (sometimes caused by antiperistaltic agents) and obstruction (secondary to luminal helminths, volvulus and intussusception) are other important problems, especially in infants and children. Enteric fever is occasionally complicated by perforation and haemorrhage; the former (which is notoriously difficult to manage) is accompanied by significant mortality. Ileocaecal tuberculosis is a major cause of right iliac fossa pathology--sometimes associated with malabsorption; amoeboma is an important clinical differential diagnosis. The colon can be involved in invasive Entamoeba histolytica infection (which, like complicated enteric fever, is difficult to manage if the fulminant form, with perforation, ensues), shigellosis, volvulus and intussusception. Acute colonic dilatation occasionally follows Salmonella sp., Shigella sp., Campylobacter jejuni, Yersinia enterocolitica and rarely E. histolytica infections. Acute hepatocellular failure is a major cause of morbidity and mortality in the tropics and subtropics. It usually results from viral hepatitis (HBV, sometimes complicated by HDV, and HCV), but there is a long list of differential diagnoses. Hepatotoxicity resulting from herbs, chemotherapeutic agents or alcohol also occurs not infrequently. Chronic liver disease and its sequelae (often long-term results of viral hepatitis) are commonplace. Haematemesis and hepatocellular failure are usually very difficult to manage due to a lack of sophisticated support techniques in developing countries. Invasive hepatic amoebiasis usually responds well to medical management; however, spontaneous perforation can occur and the consequences of this are serious. Pyogenic liver abscess, although far less common than amoebic 'abscess', carries a bad prognosis whatever the method(s) of management. Hydatidosis and schistosomiasis also involve the liver, and helminthiases are important in the context of biliary tract disease. Gall stones are unusual in most tropical settings. Acute pancreatitis is overall unusual, but chronic calcific pancreatitis can present as an acute abdominal emergency.

Use of benzimidazole chemotherapy in human helminthiases: Indications and efficacy

The past two decades have seen some remarkable developments in anthelmintic chemotherapy in clinical medicine. Whereas praziquantel has revolutionized the management of many cestode and trematode infections, Gordon Cook explains how the introduction of the benzimidazoles - most importantly thiabendazole, mebendazole and recently albendazole (flubendazole, cambendazole, ciclobendazole, and triclabendazole have also been used on a very limited scale) - has had a major impact upon the safe and effective management of several important intestinal and systemic nematode and, to a leser extent, cestode infections.

The problem and control of gastrointestinal helminthiases in Zimbabwe

An overview of the problem of gastrointestinal (GI) helminthiases in Zimbabwe is given in terms of prevalence, distribution, clinical significance of individual parasites and their transmission patterns. Although data on these aspects are incomplete, the available information and the results of studies conducted elsewhere should assist in the planning and implementation of effective helminthiasis intervention strategies. Community-based integrated helminthiasis control measures that include mass chemotherapy, improved sanitation and health education are considered to be the most practical interventions and are being evaluated in Zimbabwe. This community-based approach is cost-effective, as most of the control measures are carried out on a self-help basis. Besides, local voluntary health committees provide consistent community-level surveillance to promote and motivate the population to join in the intervention measures that include improved sanitation and health education, aspects which have broader implications for improved health.