The untold story of elimination of human schistosomiasis from Gimavi village, Ratnagiri district, Maharashtra State, India: A qualitative study

Materials & Methods

Study setting

The census population of the village of Gimavi marginally increased from 769 in 1951 to 963 in 2011. According to the family health survey conducted in June 2024, there are 319 families, and the village population is 965, including eight infants, 135 adolescents (10–19 yr), and 268 senior citizens. Two rivulets flow through the village and join in the village itself, and the united rivulet flows on the north side (Fig. 2). The village has 10 Wadis/Wadas (clusters of houses). Adjacent to the rivulets, there are 65 houses. The village is on Latitude 17°30′ 36″ N and Longitude 73° 19′ 25″ E.

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Fig. 2.

The span of rivulet from Gimavi village, India. Source: Map generated using Google map (https://www.mapsofindia.com/districts-india/).

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Infrastructure for improved hygiene and sanitation

The responsible government officers constructed area-wise tanks (for washing clothes and animals) and public latrines and also regularly chlorinated water using ‘Tropical Chloride of Lime’ bags. Through the District Planning and Development Committee, two Sakavs (temporary wooden bridges) were approved, and one was constructed between 1975 and 1980 to prevent contact with stream water. Later, bridges were constructed at two sites. The earlier and present scenario is depicted in figure 3.

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Fig. 3.

(A-B)No bridge and indiscriminate use of rivulet water in 1950s. (C) The bridge and the absence of human beings in the rivulet. Source: (A-B) Ref 12, reproduced with permission from the author. (C) Photograph taken by the authors.

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Pharmaceutical interventions

Imidazole mass administration was conducted from 1979 to 1980. A team from WHO visited Gimavi in 1989–90, and then Praziquantel was made available and administered as a single dose to all the residents (about 1,000). It took 10 days to cover the whole population. A scientist from the Haffkine Institute facilitated the administration and assisted with the distribution of iron-folic acid supplementation. The probable event timeline is depicted in figure 4.

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Fig. 4.

Event timeline of Schistosomiasis elimination in village Gimavi.

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Barriers

People were unaware of the pathogenesis and were anxious; hence, initially, they did not share information or provide urine samples. Another reason for initial non-cooperation was the absence of severe disease or death. They were curious why so many people visited the village frequently. Gradually, the situation changed to good cooperation. Overall, there were no long-standing barriers.

Positive reactions

People after realizing the benefits started cooperating. The villagers received water supply and electricity as a priority over other villages. People stopped washing clothes in the stream and drinking water from the rivulet. Elected people's representatives from Gram Panchayat, Zilla Parishad (particularly the CEO for Sakav), and the Legislative Assembly were the trailblazers in the actions. As the then Health Minister was from Ratnagiri district, he took the initiative to eliminate the focus. Other department personnel helped contact the villagers and insisted on cooperation.

Opinions about actions taken

The actions were satisfactory; hence, there were no frank cases after 1990. One senior officer said,

“Prevention of contact with water habilitating snails was enough. The actions were proportionate to the severity of the problem. No other actions were warranted” (W: 76 yr old, male).

However, a few participants commented that the actions were relatively slow. A few reported that IEC should have been a core component of all departments not of the health department alone.

One response was unique. The respondent said,

“As it was the only focus of Schistosomiasis, the government could have relocated the village to some other place” (W: 63 yr old, male).

Another respondent said, “Regular snail studies and Molluscicide might have been used to control the snail population” (W: 80 yr old, male).

Recurrence

Almost all respondents felt the probability of recurrence was ‘nil to negligible’. About 30 to 35 yr have elapsed since the last case was reported. Now, water contact is almost not happening. One officer feels that

“The environment is conducive. We do not know about chronic carriers. The Government must conduct mass urine examination and thoroughly investigate infestation among snails before the final declaration of elimination” (W: 72 yr old, male).

Observations

Presently, there is a constructed bridge at the infamous spot of the stream. People are not wading through the stream.

Discussion

The discourse of this section, apart from the findings, is derived from published articles. Among snails, presence of five types of schistosomiasis has been observed³. In animals, other types of schistosome have been frequently reported from various States^{6, 7}. Endemic cercarial dermatitis is known⁸; sporadically a few cases of other schistosome species have been found in human stools⁹. Almost all sporadic cases of S. haematobium, reported before the detection of the endemic focus, mainly were Muslims and having history of travel to Africa². An episode of haematuria in a large number of children was reported in Madhya Pradesh. But it was most likely animal schistosoma¹⁰. Indigenous haematobium causing urinary involvement was never predicted because this schistosome is transmitted by Bulinus species of snail, which is not found in India. Probably the cases from Gimavi started getting recognized in 1949 with a 19 year old woman resident of Gimavi complaining painless haematuria for nine years and was admitted in JJ Hospital in Mumbai. She passed large numbers of eggs identified as those of Schistosoma haematobium. She did not have any travel history. She informed that a large number of people in Gimavi were affected with the same symptoms. Cystoscopic examination was suggestive of Bilharziasis. She was successfully treated with antimony tartrate¹¹. Although first published evidence was in 1952; the people from the village said that the disease was prevalent since about 1890⁴. The disease existed probably since 1600 century¹².

The clinical features, affected age group and the Wadi/Wadas affected described by the respondents matched the evidence published from 1952. The respondents described that the disease had affected many children, manifesting painless and mild haematuria persisting for some years⁴. Respondents' perception of maximum occurrence among children corresponds to all published studies^{4, 12–14}. The persistence of symptoms is co-terminus mainly with the death of the adult worm (taking 10 to 12 yr); reinfection does not occur due to disease-acquired immunity¹³. Elderly persons were not found to be infected, but they provided a history of past disease⁴. In the absence of knowledge of transmission, people used to wade through the stream water, fetched the water for drinking, and washed their clothes/animals; most likely, indiscriminate urination/defecation might have frequently been occurring.

The proportion of infected persons assessed by the presence of terminally spined ova ranged from 46.1 per cent (incomplete records of ova positivity or haematuria) in the 1950s to about one per cent in 1970 and 1980s^{4, 5, 12–15}. The prevalence of infection was very high in first 10 years, which declined gradually¹². Scientists from the Haffkine Institute conducted the later studies. In their survey in 1976 and 1982 only four and six persons excreted ova in the urine. Frank haematuria almost disappeared, but microscopic presence of haematuria continued. Skin test showed 20 per cent positivity in Gimavi and 1.47 to 3.28 per cent in the surrounding four villages⁵. In the school survey, 21 students out of 40 had microscopic haematuria, but none excreted ova¹⁴. The diurnal variation in excretion of urinary ova (maximum excretion during 12 to 2 PM) was confirmed in the 1980s¹⁶. About 40 per cent of cases were observed in one locality^{4, 12, 15}, adjacent to the rivulet. Many newcomers (31.5%) residing near the stream got infected within five years¹⁵. The mean number of ova excreted by the infected persons was about 2–5 per ml¹⁷.

In the village-stream F. tenuis, Paludomas obesa, Indoplanorbis Exustus, Melanoides tuberculatus, and Pisidium were observed¹⁸. Paludomus obesa and F. tenuis were predominantly found. Laboratory infection was possible only in F. tenuis¹⁹. F. tenuis (sub-genus Pettancylus) is a very small freshwater limpet. Its shell's width is about 1.3 to 2 mm, length 2.5 to 3 mm, and height 0.6 to 0.8 mm. The shells are oval-shaped, bilaterally symmetrical, opaque in colour, and brittle^{14, 20}. The infection rate with cercariae in snails was only 2.6 per cent¹². The snails produce very few (3 to 5) cercariae daily²¹. A large population of snails compensates for the limited cercarial productivity of F. tenuis. It was observed that a single leaf might shelter up to 200 snails²². Hence, the effective cercarial load was substantial. In the laboratory out of Paludomus obesa, F. tenuis, and Indoplanorbis Exustus types of snails observed in Gimavi laboratory, breeding of F. tenuis was only possible²³. The doubts about the role of F. tenuis in the transmission were removed by Gadgil, demonstrating completion of life cycle of Schistosoma haematobium in F. Tenuis in the laboratory¹⁹. In the laboratory, infection of six types of snails was attempted. Only F. tenuis could be infected¹⁹. As a next stage for establishing the life cycle, 75 to 100 batches of F. tenuis and P. obesa were exposed to active and fresh miracidia from a patient. Only F. tenuis got infected. Then, four white mice were exposed to emitted cercaria. One mouse showed the presence of worms²⁴. Later in the laboratory, 30 mice were exposed to cercarial infection; 18 became positive, and out of six hamsters, four became positive, and about 150 adult worms were recovered from infected animals. The eggs and adult worms from Gimvi material matched those of haematobium from Egypt²¹. Attempts to infect a large number of Indian snails did not succeed²⁵. But even in 2015, some scientists differed, and rather than mentioning S. haematobium suggested, Schistosome of Gimavi village²⁶.

From 1958 to 1969, Dr. Gadgil visited Gimavi frequently and, with the help of the community and the public health department, used Copper sulphate to kill the snails.This is most likely reason for declining the population of F. tenuis in the rivulet and consequently patients' number²⁷. Community participated in the construction of Sakav. Other containment measures also contributed to decreased number of patients. The medical officer from the concerned PHC categorically affirmed they did not come across patients complaining of haematuria since his appointment 1973. However, the focus did not disappear. Microscopic haematuria and excretion of ova disappeared only after mass drug administration^{14, 22}.

The vector was detected in 2020 about 150 km away from Gimavi²⁰. However, another focus is not likely to emerge. Similar environmental conditions are rampant in India; still the focus was limited to Gimavi²⁸. It did not spread to other areas for several reasons. The village was small and isolated. People travelled minimally. The rivulet is only eight km long and flows close to two villages, and then meets Vashisti river which meets the sea after flowing for about eight km. The water in estuary of the river is so saline that vector snail cannot survive. A combination of the presence of freshwater bodies, a vulnerable vector population, contamination by human urine, and barefoot wading through the water, all of which are essential for continued transmission. Hence, the recurrence of transmission in the study village (Gimavi) after the elimination initiative was least likely. Various multipronged actions taken by the government, may were probably slow, but eliminated the focus. We hope that the government will officially declare elimination after extensive search for infected vector, and subclinical cases. It should happen at the earliest.

The principal investigator was involved twice in the Government actions of eliminating schistosomiasis and he had first-hand information. This study has some limitations. Most of the people participating in the investigation had forgotten the details. Some healthcare workers (Gramsevaks), and Panchayati Raj's elected representatives were unavailable; either they had migrated or expired. We could not get any official records from the sub-centre, primary health centre, or district health office. It is learnt that the files stored at State level including of Ratnagiri district were destroyed while weeding out old records.