Himalayan glaciers, source of water for the innumerable rivers that flow across the Indo-Gangetic plains, are receding. And that too at a phenomenal rate. As they continue to recede, incidents of landslides, changes in river regimes and floods will increase. But only while the glaciers last. If global warming is the cause of this decline, then we can expect glaciers to disappear one day. In the long run, with large sections of these glaciers gone, the rivers will dry up. Impacts on the flora and fauna, and the 500 million people inhabiting the great Indian plain are hard to imagine. All we can conjecture today is, a few decades from now, the nation will experience a great thirst
Glaciers beating retreat
On august 4, 1985, a moraine-dammed glacial lake, Dig Tsho, burst in the Khumbu Himal area of Nepal. Within four to six hours, the lake had emptied into Lagmoche valley, one of the tributary valleys of the river Bhote Kosi, which flows along many Sherpa settlements. For more than 90 km, the flood waters -- 10 to 15 metres high -- surged through the valley in the form of a huge "black" mass of debris.
Trees and boulders were dragged and tossed around, causing landslides of varying sizes. Entire trails of the nearly complete Namche Small Hydel Project, 14 bridges and numerous houses that dotted the river disappeared in a few hours.
Swiss scientists Daniel Vuichard and Marcus Zimmermann studied the catastrophe in detail. They concluded that the incident was one of several possible disasters which resulted from the thinning and receding of glaciers.They even warned about the frequency of such outbursts in the Himalaya in the future.
" Glaciers in the Himalaya are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 is very high," says the International Commission for Snow and Ice ( icsi ) in its recent study on Asian glaciers. "But if the Earth keeps getting warmer at the current rate, it might happen much sooner," says Syed Iqbal Hasnain of the School of Environmental Sciences, Jawaharlal Nehru University, New Delhi. Hasnain is also the chairperson of the Working Group on Himalayan Glaciology ( wghg ), constituted in 1995 by the icsi.
"The glacier will be decaying at rapid, catastrophic rates. Its total area will shrink from the present 500,000 to 100,000 square km by the year 2035," says former icsi president V M Kotlyakov in the report Variations of snow and ice in the past and present on a global and regional scale (see table: Receding rivers of ice ).
With the end of the Little Ice Age (1430 to 1850), glaciers have been retreating with the rise in atmospheric temperatures. "In the last 100 years alone, the global mean temperature has increased by about 0.5 to 1 c ... and the rapid receding of glaciers, to a major extent, is a consequence of global warming," says Jagdish Bahadur, a leading glaciologist and former joint advisor at the Department of Science and Technology, New Delhi.
In geological terms, the Dig Tsho lake burst was a very recent event. But, despite warnings and several reports of receding glaciers in India, there has been no attempt to study the glaciers that dot the northern and eastern part of the country.
Himalayan glaciers cover about three million hectares or 17 per cent of the mountain area as compared to 2.2 per cent in the Swiss Alps. They form the largest body of ice outside the Polar caps. The 15,000-odd Himalayan glaciers form a unique reservoir which supports mighty perennial rivers such as the Indus, Ganga and Brahmaputra which, in turn, are the lifeline of millions of people. The Gangetic basin alone is home to 500 million people, about 10 per cent of the total human population.
But whenever disaster strikes in the form of floods or landslides, no one thinks beyond the immediate damage control and rescue operation. The tragedy is forgotten by the end of the monsoons. Another year, another string of tragedies follow. There is no effort to study the problem in detail. And policymakers are yet to comprehend the gravity of the problems caused by receding glaciers.
This not only implies more Dig Tsho-like tragedies in the near future. It means more water in the rivers. "But, in the long run, the melting of glaciers also means drying up of rivers," says Hasnain. "Most of the rivers in northern India originate from glaciers. About 70 to 80 per cent of the water in these rivers come from snow and glacial melts, and the rest from monsoonal rains." Does this mean that the Ganga, Indus, Brahmaputra and the innumerable rivers that criss-cross the entire northern Indian plain will become seasonal rivers in the near future? "This is not unlikely," warns Hasnain.
receding rivers of ice
Record of retreat of some glaciers in the Himalaya
||Retreat of Snout (metre)
||Average retreat of Glacier (metre/yr)
Glacier (Himachal Pradesh)
Pindari Glacier (Uttar Pradesh)
Glacier (Uttar Pradesh)
Glacier (Uttar Pradesh)
Shigri Glacier (Himachal Pradesh)
Shigri Glacier (Himachal Pradesh)
Glacier (Uttar Pradesh)
Melting into thin air
B etween 40 and 50 million years ago, the Indian subcontinent collided with the rest of the Asian landmass. This collision caused the Earth's crust to buckle and rise forming the Himalaya. The uplift of the Himalaya was a gradual process over a long period. As the elevation of the mountains rose above the permanent snowline, it was transformed into "the abode of eternal snow and ice" forming the glaciers. For over two million years, these glaciers have sculpted the Himalayan landscape and influenced the course of human history.
"Himalayan glacial snowfields store about 12,000 cubic kilometres of freshwater and have a significant cooling affect in the entire region," says Bahadur. "The moisture-laden environment acts as a coolant for the region, thus creating an area of mega-biodiversity in flora and fauna."
"These glaciers are, in turn, affected by various factors such as changes in the energy output from the Sun and anthropogenic (or human-induced) changes," says Bahadur. But the receding and thinning of glaciers can be blamed primarily on the increase in emission of greenhouse gases.
Scientists had expected the five-kilometre-long Dokriani Bamak glacier in Himachal Pradesh to grow after a severe winter in 1997. Instead, it retreated by 20 m in 1998, compared to an annual average of 16.5m over the past five years. "This is a phenomenal melt rate," says Joseph Gergan, a geologist at the government-run Wadia Institute of Himalayan Geology ( wihg ) at Dehradun.
But Dokriani Bamak is just one of several glaciers that feed the Ganga. The Gangotri glacier, too, has been receding alarmingly in recent years, says Bahadur. "From observations dating back to 1842, the rate of recession of the snout -- the point at which the glacier ice ends -- has been found to have increased more than two-and-a-half fold per year," he says. Between 1842 and 1935, the glacier was receding at an average of 7.3m every year, whereas between 1935 and 1990, the rate of recession had gone up to 18 m a year. "The increase can be ascribed in part to the phenomenon of global warming and also to the environmental impact of increasing human activities in the Himalaya," he says. All these affect precipitation which is the source of nourishment for the glaciers, says Hasnain.
The glaciers in the Western Himalaya are fed by winter and summer precipitation. But those in the eastern and central Himalaya get their nourishment only from summer precipitation. "With only the summer precipitation to depend on, the glaciers in the eastern and central Himalaya have the dual problem of receding snowline and decreased precipitation due to global warming," says Hasnain. "Besides, accumulation and melting of snow takes place at the same time in these glaciers."
Hasnain has another dimension to add, "The recession is also the highest in the central and eastern Himalayan glaciers because, compared to the rest of the world, the population density near these glaciers is very high." Most of the people living in this area are economically backward and the consequent deforestation has adversely affected the glaciers, adds Bahadur.
It is important to understand that, in summer, there is a higher probability of precipitation resulting in rain than in winter, explains Hasnain. In cases where temperatures are higher than normal years, there are three negative effects on glaciers: increased proportion of rain in the precipitation which reduces accumulation by snowfall; higher temperatures increase melting; and decreased albedo due to decrease of snowfall.
The wghg , of which Hasnain is chairperson will submit its final report to icsi in July 1999. "Ironically, we have very little information on India because, apart from the possible causes of recession, we do not have many weather monitoring stations near glaciers to collect information and create a database," says Hasnain. "The glaciers in Nepal are better monitored. Our government is totally blind to the urgency of the problem. Just one glacier monitoring station has been set up and that stopped functioning within two months," he says.
Hasnain is also a member of the Flow Regime from International Experimental and Network Data ( friend ), an organisation recently launched by Nepal, Bhutan, Pakistan, China and Bangladesh to study the glaciers. "Strangely, India is not participating in this very important regional activity supported by unesco ," says Hasnain. "It is beyond my comprehension why the government is ignoring these initiatives, though the Himalayan waters are the lifeblood of millions of Indians."
Droughts after deluges
Glaciers , the huge and seemingly sedate rivers of ice, are the source of life and, ironically, death too. These masses not only add to the serene and pristine beauty of the higher reaches of the Himalaya, they are also the source of north Indian rivers. Thus, with global warming on the rise and many glaciers retreating at an alarming rate, it is time to assess the potential of the glaciers, which are one of the least studied natural phenomena in India.
The rather crowded mountain regions of north India are vulnerable to the consequences of receding glaciers. "Cloudbursts, avalanches, landslides, glacial lake outburst floods ( glof s), mudflows and earthquakes. These natural hazards could increase in frequency," says Bahadur. "If a glof occurs it can change the course of a river which can rise more than 10 feet and cause untold misery to all life forms in the Himalayan region."
The thinning and retreat of Himalayan glaciers is resulting in the formation of new moraine-dammed lakes and the enlargement of existing ones. Small ponds on the surface of lower glacier tongues are also increasing in size and coalescing. The retraction of the glaciers leads to influx of huge quantities of water into glacier lakes. When the water level in the glacial lake rises, it breaches the dam formed of ice, boulders and sand (see diagram: Ready to burst ) .
Since 1956, a new lake has been noticed on the lower part of the Imja glacier below Lhotse. It has grown to about 50 hectares. There are now at least 50 ice-dammed and moraine-dammed lakes in the Dudh Kosi and Arun catchment area in eastern Nepal-southeastern Xizang in China. But while little is known about the frequency of collapse of these dams, their sheer number is impressive. A study of the Dig Tsho glof gives an idea of the extent of damage caused by such a disaster.
Several Himalayan glaciers are retreating, thus increasing the chances of glof s. Such hazards will, perhaps, hit India the hardest. Their effect on a ancient civilisation formed around the Indus and the Gangetic basins is anybody's guess. Vikram Chandra Thakur, wihg director, predicts that if the Himalayan glaciers continue to retreat at their current pace over the next 25 years, the Ganges will swell and then -- with the most vulnerable portions of the glaciers gone -- touch perilously low levels in summer.
Most of the major north Indian cities have sprung up around rivers. The Ganga, mother of all rivers and venerated by Hindus, flows through many pilgrimage sites such as Rishikesh, Varanasi and Allahabad, also some of the most populated areas in the entire country. Agriculture is the primary source of income for the population living in these areas. "Since socio-ecology in these areas is directly linked to water, it is difficult to imagine the impact of seasonal or no rivers at all. One thing is for sure, it will be an ecological disaster," says Hasnain.
The impact on dams is also noteworthy. Since the Himalayan glaciers carry the maximum amount of silt and sediment (compared to glaciers elsewhere), "more water may mean siltation of dams. The lifespan of dams may also be shortened considerably. There is also a danger of breaching of dams in case of cloudbursts and glof s", says Bahadur.
Gergan notes that projects such as the massive Tehri Dam, under construction on the Bhagirathi river, the main tributary of the Ganga in Uttar Pradesh, are not taking into account glacier-induced fluctuations in the river's flow. "More glacial melting means much higher silt loads, which reduce the life of dams and reservoirs," he says. "This is exactly what is happening to the Bhakra-Nangal dam in the Punjab which receives meltwater from several glaciers," says Hasnain.
Melting of glaciers will also affect the diverse flora and fauna of the mountain region. Says A R K Sastry, director, Biodiveristy Hotspot Conservation Programme, Worldwide Fund for Nature, "As the glaciers, recede there will be a change in the moisture level of the region which could lead to hydrological imbalance. This could pose a potential danger to the high altitude wetlands that support various life forms." However, very little study has been done on the impact of receding glaciers on the flora and fauna of the Himalaya.
Need for monitoring
"In India, there is very poor database on glaciers. And whatever exists is in the form of snapshots. On the other hand, excellent studies have been conducted on Nepal's glaciers. So we presume their conclusions would also be applicable for glaciers in our country, particularly those in Sikkim, Garhwal and Kumaon Himalaya," says Hasnain.
Bahadur calls for an integrated study of the country's glaciated regions and projects in cooperation with neighbouring countries. "There is a need to monitor high-altitude glaciated regions to understand the natural processes and the magnitude of anticipated natural hazards for relief measures," he says.
Suitable blends of traditional and modern concepts are needed to contain damage to glaciers and to ensure more harmonious environmental conditions are created in the mountains. "This becomes even more important in the light of global warming due to the greenhouse effect and scientific knowledge of glacier-climate relationship is insufficient to address the effect and consequences of these climate changes in the high terrain," says Bahadur.
Based on papers by Jagdish Bahadur, former joint advisor, Department of Science and Technology, and Ajay K Naithani, department of geology, Garhwal University. Reportage by Samyabrata Ray Goswami. Written by Mridula Chettri
Is the alarm justified?
According to data from the National Institute of Communicable Diseases ( nicd ), Delhi, and the government of Bihar, 54,650 cases were reported in Bihar in 1990 and 59,611 cases of kala-azar in 1991. However, the numbers were placed close to 250,000 by an expert team constituted by the government of India in 1991. The team was chaired by C P Thakur, head of the Kala-azar Research Centre of Balaji Utthan Sansthan, Patna, who is now a member of Parliament.
With only one in five cases being recorded, discrepancies in statistics are to be expected, adding to the difficulty of assessing the magnitude of the problem. The most recent government data for Bihar records 15,485 cases for 1997 and 6,750 cases in 1998 (till May). Whatever the exact numbers may be, Bihar is definitely the worst-hit state (see table: Bihar: a state of turmoil ).Kala-azar cases are coming in not just from northern Bihar, which has invariably been the worst hit area in the past, but from all the districts of the state. "While northern Bihar is in the grip of kala-azar, southern Bihar is suffering from malaria. Both the diseases are poised to reach epidemic proportions," says Mahabir Das, former director-in-chief of Bihar's department of health. "The next epidemic will be a more virulent type as the disease has spread in all directions," says Thakur.
Kala-azar is now crossing geographical boundaries. From the plains of northern Bihar, it has spread to most parts of Bihar. In West Bengal, 1,647 cases were officially reported in 1991. A study by nicd , the principal national research authority for diseases such as malaria and kala-azar, shows that 181 cases were brought to Delhi hospitals in 1995. Uttar Pradesh, Mahrashtra, Tamil Nadu and Assam have also been affected, and Karnataka reported its first case in 1990. It is possible that kala-azar spread to these states through migrant labour populations from Bihar. But how the disease actually spread remains open to debate.
Earlier considered limited to villages, urban areas are also reporting cases of kala-azar now, nicd data shows. nicd officials point out that all cases reported in Delhi pertained to people residing outside the city. They claim kala-azar poses no threat to Delhi because urbanisation leads to a decline in kala-azar, using the reasoning that development leads to a decline in disease.
However, N L Kalra, kala-azar expert and consultant to the Malaria Research Centre in Delhi and also to the World Health Organisation, differs. "It is hard to say whether they are impor-ted cases or not. nicd has only collected data [in Delhi]. It is regrettable that they stopped there. They should have conduc-ted epidemiological studies and traced the origin of the cases."
" P argentipes (the sandfly) is prevalent throughout the country," Kalra points out. And urbanisation can mean an increased risk of transmission, he says. "Chances of picking up infection and transmitting it to another person are very high. In an urban area, risks are much higher [than in rural areas]." Kalra postulates that the lack of cattle in urban areas means that humans will be the source of blood for the sandfly.
From a global perspective, kala-azar remains in the background as a poor person's disease. Economic and political agendas determine which diseases are researched and those that are to be left out. Tropical diseases get a backseat in international research ventures. Tore Godal of who 's Tropical Disease Research ( tdr ) programme in Geneva sheds some light on the situation: "Despite the fact that 90 per cent of the global disease burden occurs in the tropics, only about 5 per cent of global health research and development investment is directed at reducing that burden."
Besides, most drugs to treat kala-azar are not reliable any more. About 40-50 per cent of the patients have developed resistance to drugs available in the market, says T K Jha, medical director of Kala-azar Research Centre, Muzaffarpur. Another worrying aspect about chemical drugs is their toxicity and side-effects.
The first line of treatment is the drug sodium antimony gluconate ( sag ), to which patients have stopped responding. The second-line drugs - pentamidine, amphotericin B or allopurinol - are more toxic than sag .
P R Arbani of the South East Asia Regional Office of who in New Delhi points out that the transmission dynamics of kala-azar are not clear.
He questions why a cluster of houses in Bihar can be found affected by kala-azar while houses 50 metres away have no kala-azar. But, before international attention comes, the national programme must also be strengthened. At present, there is no separate government programme for kala-azar. Control of kala-azar falls under the National Malaria Eradication Programme ( nmep) , and is seen simply as a side-benefit of malaria control.
state of tumoil
cases of kala-azar in India are reported from Bihar
||Number of cases reported in India
||Number of cases reported in Bihar
||Percentage of cases in Bihar
Ecological changes have contributed to the emergence of kala-azar in some areas. Dams and irrigation projects create ideal conditions for sandflies to breed. Between 1966 and 1976, 29 cases of kala-azar from five districts in south Gujarat adjoining Tapi, Mahi and Narmada rivers were admitted to the Baroda Medical College (bmc ). The state had just introduced new irrigation projects (see box: Kala-azar in Gujarat ).
Epidemiological studies conducted by the bmc in 1977 reported that over 62 per cent of the cases of kala-azar were among agricultural labourers and farmers. Since 1976, however, there have been no references to the disease in health department reports. As malaria is endemic in the area and the epidemiology of kala-azar is quite complex, it is possible that deaths due to kala-azar are ascribed to malaria."Whether deaths are due to kala-azar or malaria, they get a single label of death due to malaria," Kalra said on July 7, 1998, at the National Conference on Health and Environment organised by the Delhi-based Centre for Science and Environment.
The lack of investigations after 1977 has proved to be a major impediment. Kalra says that the origin of cases of kala-azar that came up in Vadodara was not investigated, hence a great opportunity was lost to understand the transmission dynamics of the disease in an area that does not have ideal physical conditions for its spread. It is for this reason that it is difficult to say whether kala-azar could emerge at other irrigation sites.
Deforestation can also lead to the introduction of kala-azar in previously unaffected areas. Sub-Himalayan belts have reported sporadic cases of kala-azar. This defies a precondition for the presence of kala-azar: an altitude of less than 600 metres (m) above sea level. In Jammu and Kashmir, the disease has been detected at an altitude of 2,000 m, and in Himachal Pradesh at altitudes ranging between 300 m and 1,800 m. Nine cases were reported in 1989 and nine more in 1995 in Uttar Pradesh's Garhwal region.
All the above-mentioned areas have lost their forests. Deforestation causes increased contact between humans and sandflies as in the absence of wild animals, sandflies shift their attention to humans. Increased host-parasite contact in turn increases the rate of transmission, often leading to an epidemic.
This has been the case in Assam. The state's hospitals recorded 27 cases of kala-azar between 1974 and 1979. No investigation was conducted thereafter. At present, kala-azar is under control in Assam due to spraying of the pesticide dichloro diethyl trichloroethane ( ddt ). "But as soon as ddt is withdrawn, in all likelihood there will be a flare-up of kala-azar because it has not been eradicated; it is just simmering," Kalra says.
How did it get so bad?
The story began over a century ago. Between 1862 and 1872, 'Burdwan' fever was reported in what is now West Bengal, and this was most likely the first report of kala-azar. Early epidemics were often confused with malaria. Only in 1903 did W B Leishman and C H Donovan trace the parasite, hence the name Leishmania donovani . Kala-azar hit the Garo Hills of Assam in 1863, and subsequent epidemics hit Assam from 1890 to 1900. Bihar's first case was reported in 1882, and there were severe epidemics between 1933 and 1937. Although most cases came from northern Bihar, other areas such as Assam, Bengal, Uttar Pradesh, and Tamil Nadu also suffered from kala-azar outbreaks.
By the end of the 1950s, most epidemics were thought to be over following the spraying of ddt under nmep . According to C P Thakur, there were three reasons for the decline of kala-azar in the 1950s:
l ddt sprays led to a decline in populations of the sandfly;
l Use of chemical drugs; and
l Increased immunity among people arising from sub-clinical infections of kala-azar. Thakur says for every person infected with kala-azar in a village, there are four to five people with sub-clinical infections.
Assuming that kala-azar had been eradicated, spraying of ddt was discontinued in 1964, along with surveillance of the disease. But in the 1970s, kala-azar re-emerged in Bihar, and, continues to haunt the state to this day. Although nicd 's data for 1977 shows only 18,589 cases in Bihar, Thakur says the peak of the epidemic in 1977 saw 100,000 cases with 4,500 deaths. In response to the epidemic, spraying of ddt was once again undertaken from 1977 to 1980, and then stopped. After its discontinuation, there was another peak in the epidemic in Bihar in 1991-92, with 250,000 cases. In 1992, ddt was used once again and continued in 1993 and 1994, after which it was discontinued. From the end of 1995, there has once again been a rise in the number of cases.
The inference drawn: ddt can only be considered a short-term solution to the problem. Though the number of cases declined when ddt was sprayed, kala-azar cropped up again when the spray was discontinued. One reason for this is the occurrence of post kala-azar dermal leishmaniasis ( pkdl ), a relapse situation in which papules and nodules containing a high percentage of parasites appears on the skin. These serve as reservoirs of infection that can easily be picked up by sandflies. As pkdl occurs one to three years after the apparent cure of kala-azar, the rise in vector density is dangerous because sandflies have a source of infection from which they can spread the disease. This explains why spraying of ddt has failed to eradicate kala-azar (see graph: History of kala-azar in Bihar ). Finding and treating cases of pkdl is integral for eradicating the reservoir of infection.
In 1985, the Union government constituted an expert committee on kala-azar. Among other things, the committee "strongly recommended that a national kala-azar control programme should be launched immediately... failing which, besides the loss of human lives during epidemics, the problem of kala-azar in India may attain gigantic proportions and large amounts of money will be required for its control. It may even go beyond our resources." But the warning went unheeded.
Devil and the deep blue sea
With a large number of big and small rivers running through northern Bihar, floods and waterlogging are annual phenomena in the state, especially in the northern areas. Since the 1950s, succeeding state governments began building embankments along rivers to check flooding. Today, after spending Rs 764 crore on embankments in Bihar, the area of flood-prone land in the state has actually increased. This trend was first documented by Anil Agarwal and Sunita Narain in the State of India's Environment, A Citizen's Report, Floods, Flood Plains and Environmental Myths published by the Centre for Science and Environment in 1991. Along with this has increased the incidence of kala-azar. People from several walks of life say there is a direct link between the two that has not been explored. If that is true, then government policies and the money it has spent have not only failed to check flooding but have actually contributed to death and disease.
Waterlogged lands lead to a proliferation of disease vectors such as mosquitoes and sandflies. "After the flood and waterlogging in our area, more people die due to diseases carried by the sandfly , " says Sirtia Devi of Sirgati village. "Constructing a large number of embankments is total mismanagement of water," says Nalini Kant, who works with the Indo-German Social Service Society in Patna. He has recently studied traditional irrigation systems in Madhubani district of northern Bihar. The unpublished study points out that there are 20,000 ponds in the district that formerly irrigated 45,000 hectares of land. As water management was taken up by the government, these structures, which were earlier managed by communities, fell into neglect. "Today these ponds are the sources of diseases like cholera, malaria and kala-azar," says Kant.
"There is definitely a link between waterlogging and kala-azar," says Mishra. But it is yet to be explored, he adds. "Flood or waterlogging give rise to humidity which is important for the growth of sandfly," says Kamal Kishore, assistant director of Rajendra Memorial Research Institute of Medical Sciences ( rmrims ) in Patna . Embankments, irrigation canals, roads and railways built in the plains north of the Ganga often run against the grain of natural drains. The outcome is severe drainage congestion and waterlogging. Land that earlier would have been flooded only for a week or two is now inundated for months due to the embankments.
In a paper entitled Patna, Delhi and Environmental Activism: Institutional Forces Behind Water Conflict in Bihar , Dipak Gyawali of the Royal Nepal Academy of Science and Technology traces the mismanagement of rivers in northern Bihar. He points out that the rivers coming from Nepal carry great quantities of sediment. Due to this the rivers change courses periodically. Also, the flood plains have very high groundwater tables. These two factors contribute to increased waterlogging and promote an increase in the breeding areas of the sandfly. Gyawali questions the efficacy of embankment technology in this type of hydro-ecological region.
The government's policy of building embankments needs to be reviewed, and the link between waterlogging and incidence of kala-azar should be studied in detail. The time for this is now. Any delay would cost the people dearly, especially with the best drugs in the market slowly losing their efficacy.
Need for an integrated approach
While considering the strategy to deal with kala-azar, it has to be remembered that the disease affects the poorest of the poor (see box: Inheritance of the meek ). It is essential to find non-chemical vector control measures to control kala-azar, such as environmental management methods. So far, emphasis has been limited to ddt and drugs. What are the lessons to be learnt from the history of epidemics in this century.
As vectors gain resistance to ddt , the only alternative is to switch to other compounds such as organophosphates, which are more expensive to man ufacture and need to be applied more frequently. Switching from ddt to malathion, for example, would result in a five-fold increase in costs. And what will happen when the sandfly develops resistance to stronger insecticides.
In Chennai environmental management has helped to reduce the incidence of kala-azar. Between 1945 and 1952, a total of 17,932 cases were reported, and 1,264 cases between 1958 and 1961. In the past decade, the number has fallen to 11 cases. Kalra explains that the declining trend after 1961 is due to improved housing facilities and better conditions in cattlesheds, as well as due to a cleaner environment. The breeding areas of sandflies were reduced, thereby decreasing the means of its transmission. These changes, together with improved health facilities and access to medical care, were the key to Chennai's control of kala-azar in the absence of ddt .
It has been over a century now since kala-azar was first detected in India. How much longer will it continue to ravage the land? Unless authorities get their act together now and structure a multi-faceted national programme, the answer to this question could certainly be a hopeless one.
Based on research papers by CPThakur, Head, Balaji Utthan Sansthan, Patna and NLKalra, consultant, Malaria Research Centre, Delhi, with inputs from Radhika Sarin, research student at Stanford University, USA, and reports by Jitendra Verma in Patna, Kazimuddin Ahmed in New Delhi and Manish Tiwari in Vadodara
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