Ascariasis is one of the most prevalent parasitic infections worldwide, particularly in developing countries, and is caused by Ascaris lumbricoides. Diagnosis can be challenging during the early stages of infection, especially when adult helminths have not yet become established in the intestine and routine parasitological examinations yield negative results. A 40-year-old female patient was referred to a hospital in South Tehran, Iran, with various clinical manifestations, including gastrointestinal symptoms, abdominal cramps, respiratory distress, cough, wheezing, localized skin itching, and blood-tinged sputum. Routine laboratory investigations were within normal limits. On November 28, 2024, following the expulsion of an immature helminth, the specimen was sent to the Helminthology Laboratory, School of Public Health, Tehran University of Medical Sciences, for detailed parasitological examination. Three stool samples were examined using direct smear, formalin-ethyl acetate concentration, zinc sulfate flotation, and agar plate culture techniques. No helminth eggs were detected in any of the samples, and all parasitological examinations yielded negative results. Molecular characterization of the immature helminth was performed using conventional polymerase chain reaction (PCR) targeting the Cox1 gene, which yielded the expected 520-bp amplicon and confirmed the diagnosis of A. lumbricoides. This case underscores the importance of a comprehensive laboratory workup for the diagnosis of ascariasis in patients with heterogeneous clinical presentations, particularly during the early stages of infection. The combined use of molecular and parasitological methods can facilitate the early detection of cases in which adult helminths have not yet developed and routine stool examinations are negative.

Ascariasis is a helminthic infection caused by the nematode Ascaris lumbricoides and remains the most prevalent helminth infection worldwide. Although typically asymptomatic or limited to intestinal symptoms, intestinal ascariasis can present unusually as demonstrated in these two cases. The first case involves a 73-year-old male who was being treated for non-steroidal anti-inflammatory drug (NSAID) - induced upper gastrointestinal bleeding (UGIB) and was incidentally found to harbor Ascaris worms in the duodenum during endoscopy. The second case describes a 63-year-old male with decompensated liver cirrhosis who began vomiting and passing large quantities of Ascaris worms while hospitalized. Both patients responded excellently to anthelminthic therapy. The first case highlights the need to consider ascariasis in the differential diagnosis of upper gastrointestinal bleeding, either as a primary cause or in conjunction with other causes of upper GI bleeding. The second case underscores the importance of considering biliary ascariasis or ascariasis co-infection in patients with liver cirrhosis. Ascariasis continues to pose a significant public health challenge. Effective preventive strategies such as improved sanitation, enhanced personal hygiene, and routine deworming programs are crucial for reducing the disease burden and averting potentially severe complications.

We present the case of a 9-year-old girl from the Peruvian Andean Region (Ancash), diagnosed with fascioliasis, who was also suffering from severe malnutrition. Initially, she was referred for treatment of skin necrosis caused by cutaneous visceral loxoscelism, but during hospitalisation she developed persistent vomiting and pancreatitis. Magnetic resonance cholangiography showed dilation of the intrahepatic and common bile ducts. Endoscopic retrograde cholangiopancreatography identified an adult Fasciola spp. specimen. She also expelled adult worms of Ascaris lumbricoides during vomiting. Delivery of triclabendazole was initiated via a nasogastric tube initially and subsequently via the rectal route, although absorption was limited due to persistent oral intolerance. The patient later developed upper gastrointestinal bleeding and sepsis of abdominal origin and died. During this period, the patient remained on broad-spectrum antibiotic therapy, although sepsis was attributed to persistent biliary obstruction. Fascioliasis and ascariasis should remain in the differential diagnosis for pancreatitis and cholestasis in paediatric patients from endemic areas. Oral triclabendazole is the treatment of choice for fascioliasis, but surgical management should be considered in cases of persistent biliary obstruction or treatment failure, usually seen in complicated chronic infections.

Intestinal helminth infections may present with chronic gastrointestinal symptoms and can mimic inflammatory or obstructive bowel pathology, leading to diagnostic challenges. A 27-year-old previously healthy male presented with nine months of intermittent abdominal pain, nausea, and bloating with concern for partial small-bowel obstruction. He reported frequent hunting and environmental exposure associated with field dressing and preparation of wild game. Imaging demonstrated distal ileal wall thickening with upstream dilatation, and laboratory studies revealed marked peripheral eosinophilia. Despite negative stool ova and parasite testing performed after endoscopic retrieval of the parasite, colonoscopy identified a live helminth in the terminal ileum, which was retrieved endoscopically. Histopathologic evaluation demonstrated an intestinal nematode most compatible with Ascaris lumbricoides.​​​​​ Treatment with a single 400-mg oral dose of albendazole resulted in rapid symptom resolution and sustained clinical improvement on follow-up. This case emphasizes the importance of obtaining a detailed exposure history and maintaining suspicion for parasitic infection in patients with chronic gastrointestinal symptoms, eosinophilia, and small-bowel inflammation, even when stool studies are negative.

Recurrent abdominal pain (RAP) is a prevalent paediatric concern, particularly in low- and middle-income countries (LMICs) where parasitic infections are often overlooked as contributors. The aim is to evaluate stool microscopy findings among children with RAP in Enugu, Nigeria, and assess associations with age, sex, and inflammatory markers. This was a retrospective review of 168 children aged 3-15 years presenting with RAP between 2016 and 2022. Stool specimens were examined for yeast cells, Entamoeba histolytica cysts, and helminth ova. Associations with demographics and stool red blood cells/white blood cells were assessed using chi-square tests. The result showed that Yeast cells were found in 96.4% of samples, E. histolytica cysts in 64.9%, and helminth ova in 58.3%, predominantly Ascaris lumbricoides. No statistically significant associations were observed between age, sex, inflammatory markers, and organism presence (P > .05). In conclusion high prevalence of intestinal organisms in children with RAP suggests routine stool microscopy remains essential in LMICs.

Ascaris lumbricoides remains one of the most prevalent soil-transmitted helminths worldwide, with ongoing transmission in endemic regions despite long-standing control programs. This study investigated the genetic diversity, population structure, and benzimidazole resistance of A. lumbricoides across three endemic regions of Thailand using mitochondrial (cox1 and nad1) and nuclear (β-tubulin) markers. Haplotype network analysis identified 13 haplotypes within the Thailand dataset, including three newly identified haplotypes, indicating measurable genetic diversity at the local scale. When analyzed in a global context incorporating reference sequences, substantially higher haplotype diversity was observed, reflecting broad genetic diversity across geographic regions. Despite this diversity, no clear geographic structuring was detected among Thai populations, suggesting ongoing gene flow and population connectivity. Phylogenetic analyses further demonstrated that all isolates clustered within a single major lineage and shared haplotypes with Ascaris suum (infecting pig), supporting genetic overlap and potential zoonotic transmission. Analysis of the β-tubulin gene revealed exclusively wild-type alleles at codons 167, 198, and 200, with no evidence of mutations associated with benzimidazole resistance. Overall, this study demonstrates measurable genetic diversity in Thailand's A. lumbricoides populations, with no evidence of clear geographic structuring. These findings provide baseline molecular data to support future surveillance of transmission dynamics and anthelmintic resistance.

There is conflicting evidence in the literature regarding the association between parasitic infections and human ABO blood groups. Understanding which blood groups may be more susceptible to specific intestinal parasites requires additional data from diverse populations and research settings. Therefore, this study aimed to evaluate the association between intestinal parasitic infections and ABO blood group types in the Amhara region of Ethiopia. A health facility-based cross-sectional study was conducted from February to April 2025 in four cities of the Amhara National Regional State, Ethiopia. A total of 550 study participants were enrolled. Stool specimens were examined for intestinal parasites using direct wet mount microscopy. Blood typing for ABO blood groups was performed using standard agglutination methods. Data were analyzed to assess associations between parasite infection and blood group types. Among 550 participants, the overall prevalence of intestinal parasitic infections was 38.9% (214/550). The distribution of ABO blood groups was as follows: blood type O was the most common (45.3%), followed by type A (30.5%), type B (19.8%), and type AB (4.4%). The highest prevalence of intestinal parasites was observed among individuals with blood type AB (11/24; 45.8%), while the lowest was recorded among those with blood type O (93/249; 37.3%). Species-specific analysis revealed that Entamoeba histolytica was most prevalent in blood type O (93/249; 51.6%), whereas Ascaris lumbricoides showed uniformly low prevalence across all blood groups, ranging from 2.1% to 4.2%. A statistically significant association was found between ABO blood groups and protozoan infections (p < 0.05); however, no significant association was observed with helminth infections (p > 0.05). Overall, individuals with blood type AB demonstrated the greatest susceptibility to intestinal parasitic infections. However, a higher prevalence of Entamoeba histolytica was observed in those with blood type O, suggesting a potential species-specific association that warrants additional investigation. There is a significant link between ABO blood groups and protozoan infections, but this connection does not extend to helminth infections. Future community-based and molecular studies are essential to clarify the mechanisms behind these blood group-related differences in susceptibility.

Anthelmintic drugs are used to control soil-transmitted helminths that infect a third of the world's human population. There is increasing concern about the development of resistance to anthelmintic drugs because of the limited number of compounds available and there is an unmet need for new resistance-busting drugs. Here we describe the presence of a previously unrecognized endogenous acetylcholine analogue, β-alanine betaine, which may serve as an endogenous ligand for an alternate subfamily of nicotinic receptors (DEG-3/DES-2) that could be developed as novel drug targets because their analogues are not present in their human or animal hosts. We collected peri-enteric fluid from female Ascaris suum (a model for the human parasite, Ascaris lumbricoides) and subjected it to chromatography and MS/MS to reveal signals consistent with acetylcholine, choline, and β-alanine betaine but we did not recover betaine. We injected betaine into female Ascaris suum which produced no effect. However, injection of β-alanine betaine, produced characteristic pretzel coiling and injection of levamisole produced a rod-like spastic paralysis. The differences between β-alanine betaine and levamisole suggested that they activate different nAChRs subfamilies. PCR showed that messages of the DEG-3 subfamily of nAChR channels, which are betaine targets and were present in the intestine and body wall of A. suum. Calcium signaling experiments showed that β-alanine betaine increased intracellular calcium of the intestine enterocytes and electrophysiology of the body muscle cells demonstrated that β-alanine betaine produced membrane potential depolarization. In N2 elegans, application of β-alanine betaine produced gradual inhibition of motility, which was reduced in acr-20, acr-23, des-2, deg-3 and lgc-41 null-mutants. These observations suggest that, in addition to acetylcholine, β-alanine betaine - an anaerobic analog of betaine - may function as an endogenous ligand in anaerobic nematodes such as A. suum. An expanded repertoire of nicotinic acetylcholine receptor subfamilies in nematodes relative to mammals may reflect a corresponding need for diversification of cholinergic endogenous ligands in these organisms. This repertoire could allow their simpler neuronal system to perform more complex controls and be exploited for development of different and novel subfamily selective cholinergic anthelmintics.