IELTS Academic Reading Practice Test 341

Guinea worm disease, known to scientists as dracunculiasis, is caused by a parasitic worm that has no respect for borders or for the convenience of those who would eradicate it. A person becomes infected by drinking water containing the worm's larvae, and for roughly a year nothing visible happens. Then the female worm, which may be a metre long, begins to emerge through the skin, most often on the lower leg or foot, producing a blister and a burning pain so severe that sufferers will do almost anything to relieve it. Many plunge the affected limb into the nearest pond, which is precisely what the worm requires. There is no vaccine against the disease and no drug that kills the adult worm.

The cycle therefore depends on water. The worm's larvae, released into a pond by an emerging female, are eaten by tiny crustaceans called copepods, or water fleas. Anyone who drinks that water swallows the fleas, and the acid in the stomach digests them. The larvae are then released, penetrate the wall of the intestine and mature in the abdomen, where the male and female worms mate. The male dies; the female migrates to the surface of the skin. Around a year after the original drink of water she emerges, and the whole process can begin again.

In the mid-1980s the World Health Organization estimated that 3.5 million people were infected every year, in 21 countries across Africa and Asia. In 1986 the Organization adopted a resolution calling for the disease to be eradicated, and in the same year the Carter Center, founded by the former American president Jimmy Carter, began leading a campaign in partnership with ministries of health. Carter took a close personal interest in the work and remained the campaign's most prominent advocate for the rest of his life.

The campaign's central insight was that transmission can be stopped at the pond. Where possible, villages were given boreholes and hand pumps so that nobody needed to drink from surface water at all. Where open ponds remained in use, families were issued with cloth filters, and later with a plastic pipe filter that could be worn around the neck and used to drink through. Ponds were also treated with temephos, an insecticide that kills the copepods but is considered safe in drinking water at the doses used. Health education discouraged people from wading in ponds.

The second element was case containment. Volunteers were trained to watch for the tell-tale blister, and patients were taken to a containment centre, where the worm was extracted by winding it a few centimetres a day around a small stick. This is slow and painful, but it prevents the patient from entering a pond while the worm is discharging larvae. Because a person is infectious only during the weeks of emergence, keeping them away from water during that period breaks the chain. Cash rewards were offered to anyone who reported a case.

Progress was dramatic. By the late 1990s the number of reported cases had fallen by more than 90 per cent. Several countries in Asia, including Pakistan and India, eliminated the disease altogether, and so did a growing list of countries in Africa. By 2000 fewer than 75,000 cases were being reported worldwide, and the figure continued to fall. Villagers in remote areas, many of them unpaid volunteers, did most of the surveillance work on which these claims rested.

Yet eradication proved far harder than the early figures suggested. The target of wiping out the disease by 1995 was missed, as later deadlines have been. Conflict in Sudan, South Sudan and Mali interrupted programmes and displaced millions of people. Because the worm is invisible for a year, a single undetected case in a remote settlement can restart transmission long after a country believes itself to be free of it. Nomadic herders and seasonal workers move across borders that surveillance teams cannot easily follow.

Chad presented a new problem. In 2012 the worm was found in dogs, and infections in dogs there now far outnumber human cases. How the animals pick up the parasite has not been settled; one hypothesis is that they are infected by eating fish or fish waste that contains the larvae. Whatever the route, the campaign had to add veterinary surveillance, dog restraints and the burying of fish remains to measures designed for people. Some researchers regard the animal reservoir as the single greatest obstacle to finishing the job.

Even so, the numbers today are extraordinary. In recent years fewer than twenty human cases have been reported annually worldwide, and the countries still reporting them include Chad, South Sudan, Angola and Mali. The World Health Organization certifies a country as free of transmission only after three consecutive years without a case and a thorough assessment of its surveillance. Only then can the disease follow smallpox, the first human infection to be eradicated, into the history books.

For public health, the campaign's lessons are plain. A disease can be pushed to the edge of extinction without a vaccine or a drug, through dozens of unglamorous measures and thousands of local volunteers. The sums involved have been small by the standards of global health campaigns, and most of the labour has been unpaid. But the last cases are the hardest, and the final stage has now lasted longer than anyone involved in 1986 would have predicted. Eradication, it turns out, is not a moment but a long and patient siege.

The surface of the eye is the only part of the body's interior that is permanently exposed to the air, and it must stay both transparent and clean. It manages this without a blood supply: the cornea, the clear front window of the eye, contains no vessels, because vessels would scatter light. Instead, the cornea is nourished by the film of liquid that covers it, renewed with every blink, and this tear film performs a remarkable range of tasks at once. It lubricates the lids, washes away dust and microbes, supplies oxygen and carries nutrients, and smooths the microscopic irregularities that would otherwise blur vision.

Tears are produced mainly by the lacrimal glands, which sit above the outer corner of each eye, and are spread across the surface by the eyelids. Every blink draws a fresh film over the cornea and pushes the used liquid towards the inner corner, where it drains through two tiny openings called puncta. From there it passes down a short channel into the lacrimal sac and then through the nasolacrimal duct into the nose. This anatomy explains a familiar experience: when people cry, their nose runs, because the excess tears are simply draining into it.

The volume involved is tiny. The eye holds only a few microlitres of fluid at any moment, and production falls sharply during sleep, which is why many people wake with eyes that feel dry and uncomfortable. A film a few thousandths of a millimetre thick must therefore be replenished constantly, and it is the eyelids, rather than the glands, that do most of the work of keeping it even.

The film is thin, but it is organised. At the surface, glands in the eyelids called meibomian glands release an oily layer that slows evaporation; without it, the water beneath would disappear within seconds. Beneath the oil lies the watery layer produced by the lacrimal glands, containing salts, proteins and other molecules. Closest to the cornea is mucus, secreted by goblet cells in the conjunctiva, which makes the watery layer stick to a surface that would otherwise repel it. For decades textbooks described these as three distinct layers; recent work suggests that the boundaries are less tidy, with mucus forming a gel-like coating rather than a separate sheet.

Tears are also chemically hostile to invaders. In 1922 Alexander Fleming, later famous for penicillin, noticed that a drop of fluid from his own nose could dissolve bacteria on a laboratory plate, and went on to identify an enzyme that he named lysozyme. It is present in tears, saliva and other secretions, and it works by breaking down the cell walls of certain bacteria, causing them to burst. Tears also contain lactoferrin, which deprives microbes of iron, and antibodies of the type known as immunoglobulin A, together with a mixture of defensive proteins whose roles are still being mapped.

Not all tears are the same. Basal tears keep the eye comfortable all day; reflex tears flood the eye in response to grit, wind, bright light or the fumes released when an onion is cut. Those fumes contain a volatile sulphur compound that stimulates nerve endings on the surface of the eye, and the resulting flow of tears is an attempt to dilute and wash the irritant away. Emotional tears, by contrast, have a different composition, with higher concentrations of proteins and hormones. Emotional crying is thought to be largely, though perhaps not exclusively, a human behaviour.

Why humans weep when sad or moved is still not understood. The popular notion that crying releases tension and restores emotional balance has weak support: studies find that crying often leaves people feeling no better, and sometimes worse, unless they receive comfort from others. A more promising line of research treats tears as a signal. In one much-cited experiment, men who sniffed tears collected from women showed reduced sexual arousal and lower levels of testosterone than men exposed to a salt solution, though what this means for everyday behaviour is disputed. That tears carry a chemical message of some kind is now widely accepted; what the message says remains unclear.

When the system fails, the result is dry eye, one of the commonest reasons for a visit to an eye clinic. Its causes are numerous. Ageing reduces tear production; disease of the meibomian glands, probably the leading cause, allows the film to evaporate too quickly; contact lenses and some medicines interfere with the surface; and autoimmune conditions such as Sjogren's syndrome attack the glands themselves. Sustained attention to a screen matters too, because people blink far less often when reading or watching, so the film is renewed less frequently. Sufferers describe burning, grittiness and a feeling of sand in the eye — and, paradoxically, watering, as the eye produces reflex tears in response to the irritation.

Treatment is rarely a matter of simply adding water. Artificial tears help, but they lack mucus and the proteins of the real film, and they drain away quickly. Warm compresses and careful cleaning of the lid margins can unblock meibomian glands. Small plugs inserted into the puncta keep tears on the eye for longer. Omega-3 supplements have been sold in huge quantities on the assumption that they reduce inflammation, but the largest clinical trial found no benefit over a placebo, a result that surprised many practitioners. Current research is directed at mucus-producing cells, at drugs that calm inflammation of the lid glands, and at the possibility that proteins in tears might one day reveal diseases elsewhere in the body, from diabetes to Parkinson's. No such test is yet routine.

Imagine two employees telephoning their manager on a Monday morning. The first has flu, a temperature and a racking cough. The second has barely slept for a fortnight, cannot concentrate and is fighting a dread with no obvious cause. Most managers would accept the first absence without hesitation. The second is more awkward: the employee is not visibly ill, the condition cannot be confirmed, and there is a nagging suspicion, rarely spoken, that a day off will do no good anyway. This asymmetry is what the campaign for mental health days is designed to correct.

The idea has moved quickly from the margins to the mainstream. Some employers now offer a fixed number of days that may be taken for mental health without explanation; others include mental health within ordinary sick leave and train managers to discuss it. Several countries have altered their labour law, and in some places a right to disconnect outside working hours has been written into statute. The terminology varies, but the claim is the same: distress of the mind deserves the same consideration as distress of the body.

The case for parity is strong. Depression and anxiety are among the leading causes of disability worldwide, and the World Health Organization has estimated that they cost the global economy around a trillion dollars a year in lost productivity. Yet employees routinely invent reasons for absence, offering a stomach upset rather than an anxiety attack, because admitting to the second feels riskier. That silence is costly: managers who never learn why someone is struggling cannot help, and a problem that might have been addressed early is allowed to grow.

Supporters also argue that a day away from work can be an early intervention rather than an indulgence. Presenteeism, the state of being at work but too unwell to perform, is thought to cost employers considerably more than absenteeism, so the person who takes a day to recover may avoid a fortnight of useless attendance. Some evidence suggests that shorter, earlier absences reduce the length of eventual sickness absence, though the research is far from conclusive. Absence that lasts for months is much harder to reverse than a single quiet day.

Opponents raise three objections. The first is definitional: where is the line between ordinary sorrow and illness, and who is to draw it? A policy that invites employees to diagnose themselves may medicalise the unhappiness that is an unavoidable part of life. The second is abuse: if no evidence is required, will the unscrupulous take advantage? The third is cost and complexity, particularly for small firms, in which one person's absence is felt immediately and a formal policy is a burden they can ill afford.

On abuse, the evidence is reassuring but thin. Where paid sick leave has been introduced or extended, take-up has generally risen modestly and has not produced the collapse in discipline that critics predicted. But most of this research comes from a few high-income countries, and little is known about how mental health days specifically are used. The honest position is that the scale of malingering is unknown; what can be said is that fear of it has often been used to justify policies that punish the genuinely ill.

The objection about cost deserves more attention than it usually receives, but the difficulty is not unique to mental health. Every sickness policy must cope with uncertainty, and most already rely on self-certification for short absences, demanding medical evidence only for longer ones. There is no obvious reason why the mind should be held to a stricter standard of proof than the back. What is needed is not a diagnosis but a clear framework: a few short absences on trust, then a conversation and, where necessary, occupational health support.

Yet the argument over labels conceals a larger injustice. In many countries a substantial share of the workforce has no paid sick leave at all, and in some, including the United States, where there is no federal right to paid sick days, the choice is between a day's wages and a day in bed. Millions of people in precarious, part-time and gig work are excluded from protections that professionals are now debating whether to extend. For them the question is not whether a mental health day counts as sick leave, but whether any leave counts at all.

Even for the fortunate, a day off is a weak remedy for a problem often caused by the job itself. Excessive workloads, aggressive management, insecurity and a lack of control over one's own time are all associated with poor mental health, and none is cured by an occasional Monday at home. If employers offer mental health days while leaving these conditions untouched, they risk providing an alibi for inaction. Prevention means redesigning work: predictable hours, reasonable demands, training for managers and a genuine route for employees to raise concerns.

My own view is that mental health should be treated exactly like physical health in sick-leave policy, with the same entitlement, the same absence of interrogation and the same expectation of confidentiality. But the campaign should not stop there. The more important goal is universal paid sick leave, covering the low-paid and the self-employed as well as the salaried; and employers who treat a day off as a substitute for changing how work is organised have misunderstood the problem entirely.