• Cause: Schistosome spp
• Signs: often subclinical, but signs may include weight loss, diarrhea and anemia.
• Diagnosis: clinical signs, fecal examination and post-mortem examination.
• Treatment: anthiomaline, praziquantel and/or triclabendazole. Fence off water sources that harbor snails.
• Prognosis: good with treatment.

• Often subclinical but may result in production losses such as poor weight gain or increased susceptibility to other diseases.

• S. mattheei: Southeastern Africa and south Africa and North towards Tanzania and Zambia.
• S. bovis: Mediterranean, Africa and Middle East.
• S. curassoni: Senegal, Mauritania, Mali, Niger, and Nigeria.
• S. spindale: India, Sri Lanka, Indonesia, Malaysia, Thailand, and Vietnam.
• S. indicum: Indian subcontinent, Bangladesh.
• S. incognitum: India, Thailand, and Indonesia.
• S. japonicum: Far East.
• S. nasale: India, Sri Lanka, Bangladesh, and Myanmar.
  • S. nasalei: affects the nasal passages only Schistosoma nasale infection .

• All ages may be affected but young, naïve animals may be worst affected.
• Older animals in endemic areas may develop a degree of immunity to the parasite.

• A number of Schistosome species have hybridized with human variants (S. haematobium, S. mattheei, S. bovis and S. curassoni) and this is causing serious public health concerns around the world. This is particularly of concern on the African continent.
• Research has indicated that cattle are now a reservoir host for S. haematobium and S. bovis x S. haematobium. The consequences of these results on the epidemiology of the disease, the transmission to humans, and the control of the disease is significant.
• Schistosomiasis in humans is known as Bilharzia and is estimated to affect approximately 240 million people worldwide. It is considered to be a disease of poverty that affects those without access to clean water.

• The financial implications of this often subclinical disease may in fact be substantial due to loss of productivity in affected herds and increased susceptibility to other diseases.

• There are 8 species of Schistosome that affect cattle and all of these, except for S. nasale, affect the viscera.

• The adult schistosome worms are obligate parasites of the hosts vascular system and live in the mesenteric and hepatic veins. Here they feed on the host’s blood and produce eggs:
  • It is the eggs that cause the pathology and clinical signs in the final host.
  • The eggs have a sharp terminal or lateral spine and as they pass through, or become trapped in, the gut wall, liver, blood vessels (and even lungs, pancreas and bladder) they result in granulomatous lesions developing in these regions.
• Eggs are released via host’s feces and will only hatch if deposited into water:
  • The intermediate hosts are aquatic snails (Bulinus, Biomphalaria, Indoplanorbis or Lymnaea spp). After the eggs have hatched the miracidia invade the water snail host, where they develop to become cercariae.
  • Mature cercariae leave the snail and infect the bovine host either via drinking the contaminated water or via penetration of mucous membranes.
  • Within the host, the cercariae develop into schistosomula, these travel in lymph and blood to the develop into adults in the mesenteric/hepatic veins.

• Prepatent period is 45-70 days.

• Schistosoma spp are widely distributed in Africa, the Mediterranean, the Middle East, India, Sri Lanka, Indonesia, Malaysia, Thailand, Vietnam and the Far East.
• The overall prevalence of Schistosoma spp in cattle is highest during the rainy season and winter and is lowest during summer, but in monsoon zones, seasonality is less marked.
• Warm, moist climatic conditions are favorable for the growth of intermediate host snails and the development of immature fluke, hence more cercariae are shed by snails during the warm, rainy seasons.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Adeyemo P, Léger E, Hollenberg E et al (2022) Estimating the financial impact of livestock schistosomiasis on traditional subsistence and transhumance farmers keeping cattle, sheep and goats in northern Senegal. Parasites Vectors 15 (1), 101 PubMed.
• Mamane S, Jeyathilakan N, Latha B R et al (2022) Histopathological changes in visceral schistosomosis caused by Schisosoma spindale in cattle. Indian J Vet Anim Sci Res. 50 (4), 75-78 Academia.
• Giovanoli Evack J, Kouadio J N, Achi L et al (2020) Accuracy of the sedimentation and filtration methods for the diagnosis of schistosomiasis in cattle. Parasitol Res 119, 1707–1712 SpringerLink.
• Savassi B A, Mouahid G, Lasica C et al (2020) Cattle as natural host for Schistosoma haematobium (Bilharz, 1852) Weinland, 1858 x Schistosoma bovis Sonsino, 1876 interactions, with new cercarial emergence and genetic patterns. Parasitol Res 119 (7), 2189–2205 PubMed.
• De Bont J & Vercruysse J (1998) Schistosimiasis in Cattle. Adv Parasitol 41, 285-364 PubMed.
• De Bont J & Vercruysse J (1997) The epidemiology and control of cattle schistosomiasis. Parasitology Today 13 (7), 255-262 SciDirect.

Other sources of information

• World Health Organization (online) Schistosomiasis (Bilharzia). Website: www.who.int.
• Yogeshpriya S (2022) Schistosomiasis in Cattle. In: MSD Manual. Website: www.msdvetmanual.com.