4th Feb. 2018
Jabalpur
my whole life has been devoted to unravel mystery of schistosomiasis in this South Asian part of the globe. Though the journey of research on this dreaded disease is more than a century old, yet there are some puzzling problems which have still not been solved. Perhaps the most important of them , is origin of schistosomes or evolution of the blood fluke in this part of geographical area. Should we consider it a part of African schistosomes or a separate entity. Again how much it differ from another Asian schistosome -i.e. Schistosoma japonicum.
When we consider them as descended from African schistosomes, its intriguing why the blood fluke has love only to domestic animals and not spreading in human beings like African schistosomes. And when we see it as a sibling of Asian schistosome , we mesmerize with the difference between the two blood flukes S.japonicum and others. This difference is on both sides- S.japonicum is perhaps most pathogenic and secondly it utilizes an altogether a different snail host- Oncomalania.
And when India was able to find a blood fluke which perhaps exclusively affected a human race in Gimvi village of Ratnagiri district, Maharashtra , we were perhaps not capable to explore it fully and hasten to control the infection. Therefore, there remained many unanswered questions. Atleast one thing may be appreciated among we Indians- our complacent attitude. We took for granted that the blood fluke is not present in any other part of the country although geographically this area is similar to many other places; neither we bother to investigate the sequel of cercarial dermatitis , so rampant in rural part of the country.
To complicate the matter, it is not simple to detect schistosomiasis with old methods and we have to combine them with modern methods like schistosome antigen detection test in urine and feces. There are again problems of cross breeding of schistosomes at two stages - one at snail stage where a single snail can harbor more than two , three schistosomes and another is at final host stage where there are four ,five schistosome species that may exist at same time in same host.
What may be the situation in other South Asian countries where only these schistosome species are existing? I know there are some problems in making a collaborating research projects with other countries. The main one is restriction of transfer of biological material to other countries. To me , there appears only one solution under present circumstances. The Research Organizations, universities of other countries including South Asian Countries , may call me as an expert for consultation, delivering lectures, searching fields together for schistosomiasis and other parasitic zoonosis. I think extending my expertise to other countries will not face any problems , and we may throw a new light on the subject.
Though I have retired from University services, my technical interests are still alive resulting in publication of a Reference book "Schistosomes and schistosomiasis in South Asia" published in 2012 by Springer India Pvt Ltd, New Delhi ( if you are interested to know more on South Asian schistosomiasis, you must have a copy of this book ). I have also observed how our talented new research fellows are running from here and there to search literature and what difficulties they are facing in writing a research paper. Hence I have written another book "Research Guidance in Parasitology" which is being publishing by New India Publishing Agency, New Delhi 2018.
Below I am mentioning abstract of my review paper which has been published in Acta Tropica. You may search this paper , free of cost ( or I may send you a copy of the same) till March 2018 . If you think that a discussion with me may be fruitful to resolve some problems of schistosomiasis or if you wish me to have some joint work in the field , you may take my services and may write to me on my mail id . > drmcagrawal@gmail.com>
Presently you may read the paper to know my ideas about South Asian Schistosomiasis.,published in Acta Tropica Volume 180 , April, 2018 Page 76-80
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Some facts on south asian schistosomiasis and need for international
collaboration
M.C. Agrawal , V.G. Rao,⁎ a. College of Veterinary Science & A.H., Jabalpur, Madhya Pradesh, India
b National Institute for Research in Tribal Health, Indian Council of Medical Research, Nagpur Road, P.O. Garha, Jabalpur, 482 003, Madhya Pradesh, India
Keywords:
Schistosomiasis
Schistosome species
Cercarial dermatitis
South Asia
ABSTRACT
In this review, we are discussing South Asian schistosomiasis; more specifically species which are responsible for
schistosomiasis in India or South Asia –Schistosoma indicum, S. spindale, S. nasale, S. incognitum, S. gimvicum
(S.haematobium), Bivitellobilharzia nairi, Orientobilharzia bomfordi, O. dattai, O. turkestanicum and O.harinasutai,
their survival strategies such as mild pathology to the host, producing low egg number and utilizing fresh water
snails (Indoplanorbis exustus and Lymnaea luteola) in stagnant water bodies like ponds, lakes, ditches, low laying
areas, marshy lands and rice fields. Presently, correct identification of blood fluke species, their immature stages,
male schistosomes and their intermediate host details like strain variations, susceptibilities, ecologies are not
well studied. Species like B. nairi, O. bomfordi, O. harinasutai (Lymnaea rubiginosa intermediate host for
O.harinasutai in Thailand) are also not well studied. Moreover, snail species like Oncomalania spp are not from
South Asia, but species of Tricula or Neotricula are reported from this geography, which gives indications of S.
mekongi like blood fluke presence in the area. Although in humans, cercarial dermatitis is rampant in rural
population with occasional reporting of schistosome eggs in stools, human schistosomiasis is considered absent
from this region, despite finding a foci (now dead) of urinary schistosomiasis in Gimvi village of Ratnagiri
district, Maharashtra, India. There is great difficulty in diagnosing the infection in man and animals due to low
egg production, hence development of a single step antigen detection test is the need of the hour. Interestingly,
lethal effect of praziquantel was seen against S.haematobium and S.mansoni. However, this drug failed to cause
significant reduction of S. incognitum and S. spindale experimentally suggesting some differences in the biology of
two groups of the schistosomes. Triclabendazole showed adulticidal effect at a dose rate of 20 mg/kg body
against female schistosome worms, but at lower dose (10 mg/kg body wt) of the drug, a dose that is used in
treating bovine fascioliasis, it is providing chances of drug resistance of the persisting schistosomes against
triclabendazole.
Though the South Asian institutes have all the facilities to tackle issues related to existing schistosomes, it is
recommended to develop an international collaboration by establishing an international centre on schistosomiasis
in India.
1. Introduction
Schistosomiasis is a waterborne, blood flukes infection having huge
impact on morbidity and mortality among tropical parasitic diseases
next to malaria (Bhutta et al., 2014; Colley et al., 2014). Globally, more
than 800 million people are at risk of schistosomiasis and over 240
million people are infected with the parasite (WHO, 2012, 2014;
Angeles et al., 2015). The term, South Asian Schistosomiasis, has been
coined by us and a complete monograph on infection has been published
in recent years by Springer India Private Limited, New Delhi.
(Agrawal, 2012). Existing schistosomes in this region are neither
Schistosoma japonicum, S. mansoni, S. haematobium nor S. intercalatum
or any other species found in vertebrates in African, South American or
East Asian countries (Rasoamanamihaja et al., 2016; Balahbib et al.,
2017). There is no doubt that these existing blood flukes belong to family
Schistosomatidae, but their nomenclature and biology are quite
different from the other blood flukes.
https://doi.org/10.1016/j.actatropica.2017.12.022
Received 15 February 2017; Received in revised form 9 December 2017; Accepted 17 December 2017
2. South Asian Schistosomiasis
2.1. Schistosome species involved
Credit goes to Cobbold (Cobbold, 1882) in reporting schistosome
species (reported as S. haematobium) from Kolkata (earlier Calcutta),
India. and Montgomery reporting three new species namely, S. indicum,
S. spindale and S. bomfordi from this continent for the first time
(Montgomery, 1906). S. bomfordi was recovered from cattle, and was
named to honor Bomford. It however became controversial as Montgomery
described the fluke as tuberculated with more than 16 testes,
though no such parasite was recovered subsequently by any other
worker. Nevertheless, this species was first transferred to Ornithobilharzia
(Price, 1961) and subsequently to Orientobilharzia by Dutt and
Srivastava in 1961. Dutt and Srivastava (1961) discovered another similar
new species Orientobilharzia dattai, where males were atuberculated.
We strongly believe that both O.bomfordi and O.dattai are synonymous
and Montgomery by mistake probably described it
tuberculated, as was also done while describing S.spindale. Further in
1926, Chandler (Chandler, 1926) described S. incognitum from human
stool samples, while S. nasale was described by Rao (Rao, 1933) in 1933
from nasal cavity of bovines. B. nairi (Schistosoma nairi) was described
from Elephants in 1945 by Mudaliar and Ramanujachari (Mudaliar and
Ramanujachari, 1945). Gadgil and Shah (Gadgil and Shah, 1952) described
another schistosome species in man having urinary symptoms
from Gimvi village of Ratnagiri district Maharastra, which was suspected
to be S. haematobium. However, since the geographical area of S.
haematobium is different with absence of Bulinus snail species in Indian
continent, it is difficult to accept it as S. haematobium; neither it is
possible to study the parasite as the focus is dead. Therefore, we suggested
it to be renamed as S. gimvicum (Agrawal, 2012).Another
schistosome species O.harinasutai, has been suspected to exist in India
as its lateral spined eggs in a buffalo are recorded by Srivastava
(Srivastava, 1972) though no further details are reported from the
country. Earlier to this, Srivatava and Trisal (Srivastava and Trisal,
1957) and Dutt and Srivastava (Dutt and Srivastava, 1961) discovered
O.turkestanicum from Jammu and Kashmir. Thus all the four species of
Orientobilharzia (O.bomfordi, O.dattai, O.harinasutai, O.turkestanicum)
have been suspected to be present in India. With the varied biodiversity
and ecological conditions in India, it is difficult to believe that all the
existing schistosome species in the country have been discovered. Due
to lack of interest and man power, the investigations might not have
been carried out fully, otherwise there is all the possibility of identifying
new schistosome species in South Asia. Interestingly, we are not
aware that so many mammalian schistosome species (S.spindale, S.indicum,
S.nasale, S.incognitum, S.gimvicum, Orientobilharzia dattai, O.harinasutai,
O.turkestanicum, O.bomfordi and Bivetellobilha
