THE HIGH ROAD OR THE LOW ROAD?

DR. G. STRICKLAND

Some attention has lately been excited by the circumstance that in the eastern Himalaya porters accompanying travellers have taken malarial infection and developed it on the march. The porters are usually recruited in Darjeeling, whence they come, down to the valley of the Tista by Temi (3,000 feet) to Singtam (1,400 feet), where they halt. Both these places are most malarious. Moreover, infection hereabouts in late years has become exalted in virulence and is mainly of the malignant type, especially during the autumn.

It is hoped, therefore, that the following notes will not only excite more people to greater care, but also help them technically. Mine are, of course, not the first remarks printed on the subject. Many a traveller has told of the malarious nature of the Terai and lower valleys of the Himalaya. J. G. White, for example, in his Sikkim and Bhutan, wrote (p. 2):

The first zone includes the whole of the outer ranges for a depth of twenty to thirty miles. ... In this zone the valleys are unhealthy and very feverish.

Again, citing Risley (1894), he wrote (p. 10):

No one wishes to explore that tangle of jungle and fever-stricken hills, and again (p. 42):

We had to cross the Teesta below Temi. It was towards the end of the rains and we had come in for one of the last heavy downpours, and the river was in heavy flood. We could not stay in the steamy wet valley, a hot-bed of fever, so we were obliged to make the attempt to cross. Finally:

Marching at the foot of the hills at this time of the year was very trying, mosquitoes swarmed at night. ... A little place called Dorunga lies at the foot of the hills and is used as a temporary mart in the cold weather, but at this time of the year it is merely a collection of deserted thatched huts in the midst of a sea of grass, and by no means healthy, so instead of halting there I pushed on up the hills, beyond the fever-zone.

As for others, Edmund Candler, in his Unveiling of Lhasa, noted that during the rains the climate was relaxing and malarious along the foothills (p. 115), and that the road avoided the low malarious valleys of Sikkim (p. 247). Percy Brown records his opinion in his Tours in Sikhim in these words: 'The angler should be warned that the river valleys are not considered healthy.'

The Gazetteer (1907) described the Terai as 'a low malarious belt skirting the base of the Himalayas' and as a 'tract of reeking moisture and rank vegetation that Nature has marked out as a home of fever'. It goes on:

The Nepalese say that any child born to them here will not live to the age of 2 years. The tract has always been dreaded by Europeans, who used, in the days before the railway, to hurry through it as fast as they could travel, and if possible in the early morning, in order to get beyond the fatal fever zone. That such speed was necessary was proved by the fate of Lady Canning, who caught the fever which ended in her death while halting to sketch by the road-side on her return journey from Darjeeling.¹ The people who live in this tract have their energies sapped by fever and are far from virile. The death-rate is appalling, the average mortality being nearly 60 per 1,000 per annum, in the 10 years ending with the year 1900, while in this year it exceeded 71 per 1,000, and, on the other hand, the average birth-rate in the decade was only 19-4 per annum. It is an unhealthy marshy tract, formerly covered by dense malarious jungle.

The above quotations then definitely incriminate the valleys, but as the reports have all been excited by travels in the eastern sector, it is necessary now to state that a narrow tract following the whole length of the Himalayan outworks and buttresses is equally affected, the foothills and Duars of northern Assam, including the Mishmi, the Abor, and the Daphla country, to the west of the Sankosh; the foothills of Bhutan; then west of the Tista along the Terai south of Sikkim (Darjeeling district) up to the Mechi; along the Nepal Terai and beyond this along the foothills of the United Provinces and the Punjab. All along this tract the terrain must be feared just as White and the others have said that the low valleys of Sikkim must be feared. For it is a fact that this zone is uniformly subject to a very high or hyperendemic rate of malaria. This epithet, it may be explained, is the term applied to a condition of the community when over 50 per cent, of the children have some degree of enlargement of the spleen due to their infection with malaria parasite. This high infection rate in a comparatively narrow belt is the fact that the pathfinder should have emblazoned on his bandobast file.

It is usually considered that country like the Nepal Terai is so malarious because of the seepage from the enormous filtration beds of the hinterland, which crops out in a long line from east to west. But this topographical conception is not quite correct. The amount of seepage is, of course, tremendous, but it follows the contours of the hills where they delimit the valley-beds; it has, in fact, the same dendritic topography. In the seepage breeds the bad malaria-carrying mosquito, Anopheles maculatus, and its cousins. Hence the ill-reputation of the 'low, steamy valleys'. Between these are the upland ridges left by the corrading and ramifying streamlets. In the Provinces westwards the valleys become less swampy, for one reason because the rainfall in the hills is less, and possibly because the absorbent alluvium overlying the bed-rock is deeper, but the conditions, nevertheless, still favour the prevalence of the malaria-carrying mosquitoes, and malaria incidence is equally hyperendemic.

To the south this long foot-hill zone is demarcated from 'the deltaic plains' by a dry belt in which all but the greatest of the rivers disappear underground into a sponge of thousands of feet of alluvium which fills the Indo-Gangetic trough.¹

At the southern boundary of this dry belt subsoil water again crops out in a line of springs. The dry belt is comparatively free from malaria, but south of it is a particularly dangerous tract, where black- water fever is also rife, and through this zone one has often to travel in order to start on expeditions.

Before now recounting some of the hackneyed advice as what to do to cope with the danger, it may be of some interest to analyse the matter further in case it may betray some hitherto undiscovered joint in the armour which may be assailed.

In the first place one must confirm the common experience that as one ascends the hills malaria becomes a less serious menace. Thus at Yatung (10,000 feet) in the Chumbi valley there was no 'scientific’ evidence of any malaria, and at Darjeeling (7,000 feet) it may also be said to be non-existent, while at Gangtok, in 1931, at 5,800 feet, and at Marik, in 1934 (5,500 feet), there was also none.¹ On the other hand, at Kalimpong (4,100 feet) there have been slight epidemics; in 1932, during a survey of Sikkim, a great deal of malaria was found at 3,700 feet; while below this, evidence of malaria gradually became still more marked. One may therefore conclude that, from the point of view of altitude only, even 5,000 feet may not be high enough for safety: perhaps 6,000 feet should be aimed at. Anyway, generally speaking, above 6,000 feet anti-malarial precautions need not be taken.

Now within this putative malarial zone depending on altitude there are places which show no evidence of malaria, that is, there are exceptions to the rule, Rongli, for example, at about 2,200 feet on one of the eastern tributaries of the Tista, and it may be said here at once that this is apparently an example of the benefit of jungle in saving a locality from becoming malarious. Jungle has often been blamed for the incidence of malaria when probably it should not have been. Generally speaking, we know now that swampy places in the Tropics covered with jungle do not breed malaria-carrying mosquitoes.

The relative safety of travellers' bungalows in the eastern sector has not generally been ascertained, but Dr. Sur has given some relative figures for the following places in the Kalimpong sub-division.

As a rough and ready guide, however, at any level, the more a place is covered with jungle the safer it may be expected to be, and the more exposed the rivers and streams, and the more broken they are with irregular alluvia, and the more capricious their stream-level, then the more dangerous the place is likely to be, largely because of the anopheline maculatus, whose larva thrives in temporary pools of sunny, clear water.

Another factor in the matter must now be mentioned, only shortly, for it is too technical to go into fully in this place. It is that the temperature and, to a less extent, the humidity are very important. If these physical conditions be unsuitable, no mosquito that at other times can become infective will show the infection. Thus in the plains during the hot months, say from February to May, one may say that not a single anopheline becomes infected with malaria, and all the cases of the disease that are seen at this season are only relapses of an infection contracted previously. Antithetically, in the high hills, such as at Yatung in the Ghumbi valley, the temperature never rises high enough to enable the malaria parasite to develop in the mosquito.

What joy! Since in the hot-weather months mosquitoes cannot become infected either in Calcutta or, at the same time, in the high hills, as at Yatung, perhaps there is no potential malaria in the country between. Unfortunately this is not the case; between Calcutta and the high hills the physical conditions become suitable for infection, and there is an intermediate point where the infection reaches a maximum. This point, from a technical review of the evidence, is at about the 16,000-foot level. At this level, then, during the season from February to May, the physical conditions are at an optimum for the development of malaria in the mosquito.

This is an important practical matter, for obviously at this season it follows that it is the level from which to keep farthest away either below or above; one must not presume that it is necessarily safer to get to a higher level as quickly as possible. If one cannot rise quickly above 1,600 feet it is just as well to stop in the hot valley below. If, however, one is obliged to go up, the climb should be made—at this season— as quickly as possible to say 5,000-6,000 feet. Toiling up the Devil's Stairway at 13,000 feet near Gnatong in two days out of Calcutta may not seem to the jaded dweller of the plains to possess many advantages, but in the light of this thesis he may now be more pleased about it than he was.

In the autumn it is a different matter, for the plains are now becoming increasingly subject to malaria up to a maximal intensity of 100 per cent, infectivity in the proper mosquitoes. In Calcutta, in the cold weather, the same anopheline that did not in the hot weather become infected at all will now show a 100 per cent, infection rate; however, the high hills remain, as in the hot weather, passive in their disinfectivity, so now one has to do a bolt all the way as quickly as possible, knowing that the risk is declining every inch upwards from the sea-level.

Thus one may conclude that the high road is not necessarily better than the low road. It depends upon the season.

Apart from this choice of roads, mention of the hackneyed precautions, where at all necessary, will bear repetition. If one be going up to railhead by train it may be assumed that the countryside will become more or less malarious according to the season, but the mosquito-proof shutters should always be utilized and the compartment thoroughly sprayed with some mosquito repellant, such as 'Tell-shox', not forgetting some blasts under the seats; 'cosmito- quoils', those that will burn for a whole night, would also be effective: the organization of any good expedition in all its aspects needs so much thought and care, and the consequences of illness in but a single member of a party are so serious that the addition of a spray-gun and the proper fluid represents an infinitesimally small part of the total trouble that must be taken. Suitable wearing apparel is perhaps an even more important matter, because mosquitoes usually bite with greater avidity at nightfall, and if one's limbs be bared, e.g. by shorts or short-sleeve shirts, one is particularly vulnerable. By the same token people with long ears might have little bags made to draw over them!

Along the bungalow-routes in the malarious valleys a mosquito- net must certainly be used. After they have been left behind it will come in useful as an extra bed-covering, for it is very warm, better than the new-fangled blankets with meshes like a tennis net. A bag of about the size of a bed, in which to pack it up, should also be taken. This bag can be used for soiled linen as long as the net is being slung up nightly, and when the valleys have been left behind and the net stowed away there will be no soiled linen for which a bag is required. Quinine or other drugs as prophylactics are useless against infection by mosquitoes; for example, a volunteer in Calcutta was given 80 grains of quinine within the 48 hours before feeding some infected mosquitoes upon him, and yet he developed an attack of malaria at the appointed time afterwards: moreover, these drugs are vital poisons, and if given to a man on the march would depress his strength when he needs all he has got.

Much of what has been said above is scarcely applicable to the faithful 'bearers of the burden' whose health and strength is, of course, so vital a matter. One point with regard to the men, however, is that they should be overhauled before starting, a little native internal fauna predispose considerably to malaria, not to mention lassitude. The most practicable suggestion with regard to them is the selection of the best route for the time of year; in the spring they can follow the valley-casinos, in time autumn march as high as possible. The Sahiblog may, perhaps, b—y dint of taking the care suggested above, survive a halt in a bungalow near a malarious bazaar, but the bearers will not, and it must be remiembered that they are, as a rule, highly susceptible, having beren reared in the high hills. Nevertheless, though unctions like citronella oil for their ears and knees in the evenings or cheap mosquito- nets may not lead to much good, they can at least do no harm and do not cost much—at any rate less than the expense of employing casual labour to make good losses from malaria.

Was it Shelley who said that all doctors and chemists ought to be thrown into the sea? It was certainly he who wrote:

And so the Hills , here too, transcend all morbidity.

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