''Schistosoma indicum'' is a species of
digenetic trematode
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive h ...
in the family
Schistosomatidae
Schistosomatidae is a family of digenetic trematodes with complex parasitic life cycles. Immature developmental stages of schistosomes are found in molluscs and adults occur in vertebrates. The best studied group, the blood flukes of the genus ...
. The parasite is widespread in domestic animals in India and other Asian countries.
''Schistosoma indicum'' was discovered by the British scientist
R. E. Montgomery, in 1906, from a horse from Mukteswar,
Uttar Pradesh
Uttar Pradesh (; , 'Northern Province') is a state in northern India. With over 200 million inhabitants, it is the most populated state in India as well as the most populous country subdivision in the world. It was established in 1950 ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. This blood-fluke causes hepato-intestinal
schistosomiasis in many domestic animals (sheep, goat, water buffalo, cattle, camel, horse, donkey, dog, but not pigs).
It was responsible for an outbreak of pulmonary schistosomiasis, in 1981, in sheep in
Rajasthan
Rajasthan (; lit. 'Land of Kings') is a state in northern India. It covers or 10.4 per cent of India's total geographical area. It is the largest Indian state by area and the seventh largest by population. It is on India's northwestern s ...
, leading to considerable mortality. ''S.indicum'' caused considerable mortality in the sheep flocks in Andhra Pradesh and Karnataka but it was misdiagnosed as Rinder Pest, highlighting the problem of proper diagnosis of the infection in domestic animals. ''S.indicum'' has been detected from almost all the states of India and is more widespread than ''
Schistosoma spindale''.
Intermediate hosts
The parasite's most important
intermediate host is a
freshwater snail ''
Indoplanorbis exustus''
that is the sole natural intermediate host for ''S. indicum'' (and other two ''Schistosoma'' species) on the Indian sub-continent.
Earlier another snail (''Lymnaea luteola'') was also implicated in
transmission of ''S. indicum'', but subsequent research refuted that possibility.
Gimvi village dispute
A variant of ''S. indicum'', rather than ''
Schistosoma haematobium
''Schistosoma haematobium'' (urinary blood fluke) is a species of digenetic trematode, belonging to a group (genus) of blood flukes (''Schistosoma''). It is found in Africa and the Middle East. It is the major agent of schistosomiasis, the most ...
'', was suggested to be responsible for human schistosomiasis in Gimvi village, Ratnagiri district, India,
but was later disputed by other scientists. The main reasons were the use of a different intermediate host (''Ferrissia tenuis'') and final host (humans) with difference in location (urinary system) which is not possible for any variant.
Terminal-spined ''S. indicum''-like eggs have been detected in human stools. Dr. M. C. Agrawal demonstrated cross-immunity against ''
Schistosoma incognitum
''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed ''schistosomiasis'', which is considered by the World Health Organi ...
'' by immunising the host against ''S. indicum''.
References
Further reading
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{{Taxonbar, from=Q7431529
Diplostomida
Animals described in 1906
Parasites of equines
Parasitic animals of mammals