In the red-earth villages of Ghana’s middle belt, a silent parasite is moving between pets and people at a rate that has startled researchers. A new surveillance study, published in Discover Animals, has delivered the first molecular evidence that Toxocara cati—the cat roundworm—circulates in dogs in Ghana, alongside a sobering snapshot of how widely its canine cousin, Toxocara canis, is entrenched in the country’s dog population. The team, led by Papa Kofi Amissah-Reynolds of Kwame Nkrumah University of Science and Technology, screened 505 people and 442 dogs across the Ashanti and Bono East regions between January and October 2025, and what they found is a textbook case of a neglected tropical disease thriving wherever sanitation infrastructure and veterinary care lag behind human-dog contact.
The headline numbers are stark. Human seroprevalence of anti-Toxocara IgG antibodies, measured by enzyme-linked immunosorbent assay, stood at 14.5 percent overall, with a 95 percent confidence interval of 11.4 to 17.5 percent. Among children aged 6 to 15 years, seropositivity climbed to 23.9 percent, the highest of any age band, while the 16-to-30-year group registered just 4.5 percent. Males, at 18.6 percent, carried significantly more antibodies than females, and rural residents recorded 27.5 percent seropositivity—nearly five times the urban figure. The dog data were even more dramatic: 56.1 percent of sampled canines were infected, a figure that dwarfs the 5.8 to 18.8 percent rates previously documented in Ghanaian dogs and rivals the puppy-heavy prevalences above 40 percent reported in parts of Europe.
Toxocariasis is caused by ascarid nematodes whose eggs are shed in prodigious quantities by adult worms living in the small intestines of dogs and cats. Under warm, moist tropical conditions, these eggs embryonate in soil over several weeks and become infective. Humans are accidental, dead-end hosts: after ingesting embryonated eggs from contaminated soil, unwashed vegetables, untreated water, or even the fur of pet dogs, larvae hatch in the small intestine and penetrate the gut wall, migrating through the bloodstream to the liver, lungs, eyes, and central nervous system. The parasite never matures in humans, but its wandering larvae provoke granulomatous inflammation wherever they lodge, producing the syndromes clinicians know as visceral larva migrans, ocular larva migrans, and common toxocariasis—a spectrum that ranges from elevated liver enzymes, cough, wheezing, and marked eosinophilia to irreversible retinal damage and vision loss in advanced cases.
The Ghanaian team’s diagnostic architecture reflected this biology. Because larvae never develop into adult worms in the human body, stool examination is clinically useless for toxocariasis, so the researchers turned to the serology that global reviews consider the method of choice. Venous blood was drawn from participants, clotted, centrifuged at 3,000 rpm, and the resulting serum was aliquoted and stored at minus 20 degrees Celsius before being screened with the NovaTec Toxocara IgG ELISA. Every sample was tested in duplicate, diluted 1:100, incubated with antigen-coated wells at 37 degrees Celsius for one hour, and developed with an HRP-conjugated anti-human IgG detection system and TMB substrate, with absorbance read at 450 nanometers on a calibrated microplate reader. Positive and negative controls accompanied every run. The authors are candid about the method’s limits: cross-reactivity with antibodies against other soil-transmitted helminths endemic in Ghana, particularly Ascaris lumbricoides, cannot be fully excluded, and confirmatory Western blotting was not performed, so the figures should be read as population-level exposure rather than individual clinical diagnosis.
For the dogs, the story was resolved at the molecular level. Fresh fecal samples, collected immediately after defecation or from consenting owners and transported on ice to the Noguchi Memorial Institute for Medical Research, yielded roughly 200 milligrams of material each for DNA extraction. The team then deployed species-specific polymerase chain reaction assays targeting the internal transcribed spacer 2 (ITS-2) region of the parasites’ ribosomal DNA—a genetic barcode short enough to amplify reliably but variable enough to distinguish the two Toxocara species. The T. canis reaction paired the forward primer Tcan1 with the conserved reverse primer NC2, while T. cati detection used the forward primer Tcat1 with the same NC2 anchor, which binds a region downstream of ITS-2 shared by both species. Amplicons, generated through 35 thermal cycles peaking at a 58-degree annealing step, were resolved on 1.5 percent agarose gels stained with ethidium bromide and visualized under ultraviolet light against a 100-base-pair ladder.
The molecular breakdown contained the study’s most striking revelation. Of the infected dogs, 87.9 percent harbored Toxocara canis, the classic canine roundworm, but 12.1 percent were shedding Toxocara cati—the feline roundworm—marking the first time this species has been molecularly confirmed in Ghanaian dogs. The finding matters because it hints at cross-species transmission dynamics that have gone unmeasured in the region. Cats and dogs shareyards, soil patches, and in many communities food scraps and shelter, and T. cati eggs defecated by cats can persist in the same environments where dogs forage. Whether dogs are mere mechanical hosts or can sustain T. cati transmission cycles remains an open question the authors explicitly flag as warranting further investigation.
Regression analysis sharpened the risk profile on both sides of the human-dog interface. Among people, being male nearly doubled the odds of seropositivity, with an adjusted odds ratio of 2.06 (95 percent CI 1.22–3.48), while rural residence multiplied the odds more than fourfold (AOR 4.13; 95 percent CI 2.47–6.92). Lack of formal education also significantly raised the likelihood of exposure, a signal the researchers attribute to differences in occupational soil contact, hygiene knowledge, and household sanitation. Among the dogs themselves, age and provenance told the story: young adult dogs were dramatically less likely to be infected than puppies (AOR 0.18; 95 percent CI 0.10–0.30), consistent with the epidemiology of an infection in which puppies acquire larvae through the placenta and milk and harbor the heaviest worm burdens early in life. Foreign-breed dogs, meanwhile, had only about a quarter of the infection odds of local breeds (AOR 0.26; 95 percent CI 0.10–0.68), likely reflecting differences in housing, feeding, deworming access, and the degree of free-roaming behavior.
The sampling design gives the findings real epidemiological weight. Twenty-four communities were selected—twelve each in the Kumasi area of Ashanti Region and the Techiman area of Bono East—split evenly between urban and rural settings and chosen for high dog ownership, frequent human-dog contact, and visible animal defecation in public spaces. Households were enrolled by simple random sampling, dogs were sampled both from consenting owners and free-roaming animals identified with the help of community informants, and each animal was marked with washable chalk to prevent repeat sampling. The study’s ethical credentials are solid: clearance came from KNUST’s Committee on Human Research, Publications and Ethics, the work followed the Declaration of Helsinki, and animal handling adhered to World Organisation for Animal Health welfare standards.
What emerges is a picture of a parasite perfectly adapted to its niche. Ghana’s middle belt offers a tropical climate with 1,200 to 1,500 millimeters of annual rainfall and temperatures between 21 and 35 degrees Celsius—ideal conditions for egg embryonation—combined with free-roaming dog populations, irregular deworming, and a farming culture that keeps people, especially children, in constant contact with contaminated soil. Previous work in the country had already sounded alarms: a study of 566 children in the Central Region found a Toxocara seroprevalence of 53.5 percent, and research in Kintampo linked high antibody levels to active convulsive epilepsy. The new study extends that concern across a broader geography and, for the first time, anchors it in molecularly confirmed canine reservoirs.
The authors argue that their findings demand integrated, One Health responses rather than piecemeal fixes. Regular strategic deworming of dogs, particularly puppies and local-breed animals that the data identify as key reservoirs, would shrink the egg input into the environment. Hygiene education targeting children, who are both the most exposed and most vulnerable group, could interrupt the oral-fecal route through which eggs reach human hosts. Sanitation improvements, leash and roaming policies, and better access to veterinary services would compound those gains. Because the same conditions that sustain toxocariasis also sustain other soil-transmitted helminths and zoonoses, the interventions pay dividends across a whole family of neglected infections.
For now, the study stands as a rare example of paired human and canine surveillance in a neglected tropical disease, conducted with methods rigorous enough to satisfy the growing demand for molecularly grounded zoonotic data from sub-Saharan Africa. Its message travels well beyond Ghana’s borders: wherever dogs roam freely, deworming is sporadic, and children play in shared soil, Toxocara is quietly writing its signature into human immune systems. The 14.5 percent of Ghanaians in this study carrying anti-Toxocara antibodies are a visible fraction of a global burden estimated at nearly 19 percent of humanity. As the authors put it through their data, the transmission loop between village dogs and village children is not a historical curiosity—it is running now, and it can be broken.
Subject of Research: People and dogs
Subject of Research: Biology
Article Title: Molecular and serological surveillance of toxocariasis in humans and dogs in Ghana
Article References: Amissah-Reynolds, P. K., Addo, K. A., Ofori, S. A., Owusu, C. M., Abdul-Karim, Z., & Opoku, F. B. (2026). Molecular and serological surveillance of toxocariasis in humans and dogs in Ghana. Discover Animals, 3(1), Article 43. https://doi.org/10.1007/s44338-026-00180-4
Image Credits: AI Generated
DOI: 10.1007/s44338-026-00180-4
Keywords: toxocariasis, Toxocara canis, Toxocara cati, seroprevalence, ELISA, PCR, Ghana, zoonosis, neglected tropical disease, One Health
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William Thompson. (September 10, 2026). Human and dog toxocariasis in Ghana revealed by molecular and serological surveillance. Scienmag. https://scienmag.com/human-and-dog-toxocariasis-in-ghana-revealed-by-molecular-and-serological-surveillance/
William Thompson. “Human and dog toxocariasis in Ghana revealed by molecular and serological surveillance.” Scienmag, 10 September 2026, https://scienmag.com/human-and-dog-toxocariasis-in-ghana-revealed-by-molecular-and-serological-surveillance/. Accessed 10 September 2026.
William Thompson. “Human and dog toxocariasis in Ghana revealed by molecular and serological surveillance.” Scienmag. September 10, 2026. https://scienmag.com/human-and-dog-toxocariasis-in-ghana-revealed-by-molecular-and-serological-surveillance/
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Tags: canine Toxocara canis prevalencechildhood risk of toxocariasisdog and human parasite transmissiondog population infection rates in Ghanadog-human transmission of Toxocaraenzyme-linked immunosorbent assay forhuman toxocariasis seroprevalenceimpact of sanitation on parasitic infectionsmolecular detection of Toxocara cati in dogsmolecular detection of Toxocara in dogsneglected tropical diseases in West Africaneglected tropical parasitic diseases in Ghanaparasitic infection epidemiology in rural communitiesrural vs urban Toxocara prevalenceserological surveillance of Toxocara antibodiesseroprevalence of Toxocara antibodiesToxocara cati in GhanaToxocara infection in childrenToxocariasis in Ghanaveterinary and public health surveillanceveterinary publiczoonotic transmission of roundwormszoonotic transmission of Toxocara
