Fasciolosis

This article is about the infection. For the organism, see Fasciola.
Not to be confused with Fasciolopsis.
Fasciolosis
Other namesFascioliasis, fasciolasis, distomatosis, liver rot
Fasciola hepatica
SpecialtyInfectious disease, hepatology
SymptomsAbdominal pain, nausea, yellow skin
ComplicationsPancreatitis, anemia[1]
CausesFasciola flatworms
Risk factorsEating raw watercress
Diagnostic methodStool sample[2]
PreventionProper food preparation
MedicationTriclabendazole[1]
Frequency2 millions[1]

Fasciolosis is a parasitic worm infection caused by the common liver fluke Fasciola hepatica as well as by Fasciola gigantica. The disease is a plant-borne trematode zoonosis,[3] and is classified as a neglected tropical disease (NTD).[4][5] It affects humans, but its main host is ruminants such as cattle and sheep.[4] The disease progresses through four distinct phases; an initial incubation phase of between a few days up to three months with little or no symptoms; an invasive or acute phase which may manifest with: fever, malaise, abdominal pain, gastrointestinal symptoms, urticaria, anemia, jaundice, and respiratory symptoms.[6] The disease later progresses to a latent phase with less symptoms and ultimately into a chronic or obstructive phase months to years later.[7][8] In the chronic state the disease causes inflammation of the bile ducts, gall bladder and may cause gall stones as well as fibrosis.[4] While chronic inflammation is connected to increased cancer rates, it is unclear whether fasciolosis is associated with increased cancer risk.[9]

Up to half of those infected display no symptoms,[4] and diagnosis is difficult because the worm eggs are often missed in fecal examination.[4] The methods of detection are through fecal examination, parasite-specific antibody detection, or radiological diagnosis, as well as laparotomy. In case of a suspected outbreak it may be useful to keep track of dietary history, which is also useful for exclusion of differential diagnoses.[4] Fecal examination is generally not helpful because the worm eggs can seldom be detected in the chronic phase of the infection. Eggs appear in the feces first between 9–11 weeks post-infection. The cause of this is unknown, and it is also difficult to distinguish between the different species of fasciola as well distinguishing them from echinostomes and Fasciolopsis.[4] Most immunodiagnostic tests detect infection with very high sensitivity, and as concentration drops after treatment, it is a very good diagnostic method.[4] Clinically it is not possible to differentiate from other liver and bile diseases. Radiological methods can detect lesions in both acute and chronic infection, while laparotomy will detect lesions and also occasionally eggs and live worms.[4]

Because of the size of the parasite, as adult F. hepatica: 20–30 × 13 mm (0.79–1.18 × 0.51 inches) or adult F. gigantica: 25–75 × 12 mm (0.98–2.95 × 0.47 inches), fasciolosis is a big concern.[4] The amount of symptoms depend on how many worms and what stage the infection is in. The death rate is significant in both cattle (67.55%) and goats (24.61%),[10] but generally low among humans.[citation needed] Treatment with triclabendazole has been highly effective against the adult worms as well as various developing stages.[4][6] Praziquantel is not effective, and older drugs such as bithionol are moderately effective but also cause more side effects. Secondary bacterial infection causing cholangitis has also been a concern and can be treated with antibiotics, and toxaemia may be treated with prednisolone.[4]

Humans are infected by eating watergrown plants, primarily wild-grown watercress in Europe or morning glory in Asia. Infection may also occur by drinking contaminated water with floating young fasciola or when using utensils washed with contaminated water.[4] Cultivated plants do not spread the disease in the same capacity. Human infection is rare, even if the infection rate is high among animals. Especially high rates of human infection have been found in Bolivia, Peru and Egypt, and this may be due to consumption of certain foods.[4] No vaccine is available to protect people against Fasciola infection.[11] Preventative measures are primarily treating and immunization of the livestock, which are required to host the live cycle of the worms. Veterinary vaccines are in development, and their use is being considered by a number of countries on account of the risk to human health and economic losses resulting from livestock infection.[4] Other methods include using molluscicides to decrease the number of snails that act as vectors, but it is not practical.[4] Educational methods to decrease consumption of wild watercress and other waterplants has been shown to work in areas with a high disease burden.[4]

Fascioliasis occurs in Europe, Africa, the Americas as well as Oceania.[4] Recently, worldwide losses in animal productivity due to fasciolosis were conservatively estimated at over US$3.2 billion per annum.[12] Fasciolosis is now recognized as an emerging human disease: the World Health Organization (WHO) has estimated that 2.4 million people are infected with Fasciola, and a further 180 million are at risk of infection.[13]

  1. ^ a b c "CDC - Fasciola". Retrieved December 31, 2018.
  2. ^ "Fascioliasis - Infectious Diseases - MSD Manual Professional Edition". Richard D. Pearson. Retrieved 18 August 2020.
  3. ^ Mas-Coma S, Bargues MD, Valero MA (October 2005). "Fascioliasis and other plant-borne trematode zoonoses". Int. J. Parasitol. 35 (11–12): 1255–78. doi:10.1016/j.ijpara.2005.07.010. PMID 16150452.
  4. ^ a b c d e f g h i j k l m n o p q r Farrar J, Hotez P, Junghanss T, Kang G, Lalloo D, White NJ (2013-10-26). Manson's Tropical Diseases. Elsevier Health Sciences. ISBN 9780702053061.
  5. ^ "Neglected Tropical Diseases". cdc.gov. June 6, 2011. Retrieved 28 November 2014.
  6. ^ a b "CDC - Fasciola - Treatment". www.cdc.gov. Retrieved 2015-07-17.
  7. ^ Mas-Coma S, Bargues MD, Esteban JG (1999). "Human fasciolosis.". In Dalton, JP (ed.). Fasciolosis. Wallingford, Oxon, UK: CABI Pub. pp. 411–34. ISBN 0-85199-260-9.
  8. ^ Esteban J, Bargues M, Mas-Coma S (1998). "Geographical distribution, diagnosis and treatment of human fascioliasis: a review". Res. Rev. Parasitol. 58: 13–42.
  9. ^ "Fasciolosis and tumour growth" (PDF). Göteborgs universitetsbibliotek: Logga in via proxy. Retrieved 2015-07-17.
  10. ^ Rahman AK, Islam SK, Talukder MH, Hassan MK, Dhand NK, Ward MP (8 May 2017). "Fascioliasis risk factors and space-time clusters in domestic ruminants in Bangladesh". Parasit Vectors. 10 (1): 228. doi:10.1186/s13071-017-2168-7. PMC 5422951. PMID 28482863.
  11. ^ "CDC - Fasciola - Prevention & Control". www.cdc.gov. Retrieved 2015-07-17.
  12. ^ Spithill TW, Smooker PM, Copeman DB (1999). "Fasciola gigantica: epidemiology, control, immunology and molecular biology". In Dalton, JP (ed.). Fasciolosis. Wallingford, Oxon, UK: CABI Pub. pp. 465–525. ISBN 0-85199-260-9.
  13. ^ Anonymus (1995). Control of Foodborne Trematode Infections. WHO Technical Series No. 849. WHO, Geneva, 157 pp.