In Britain we no longer expect to suffer from illnesses associated with malnutrition, poverty and the dark ages of medicine. But news last week that the incidence of rickets among children is increasing suggests that our confidence may have been misplaced. Dr Zulf Mughal of St Mary's hospital in Manchester believes that many cases are missed by doctors unfamiliar with a condition not routinely seen in Britain for more than 50 years. "If you are attuned to the problem, if you walk around any area with high immigration, you often see children walking with a funny-looking gait that could well be rickets," he says.
Rickets is not the only "dead" ailment to be undergoing a revival.
There are 30 diseases which must be reported to the authorities under the public health (infectious dis eases) regulations of 1988: alongside cholera and the plague are conditions such as measles and rubella, which were declining thanks to immunisation.
However, an outbreak of measles in Dublin this year showed how these "declining" diseases can escape medical control: two people died and 100 were hospitalised. Concerns about the safety of the MMR (measles, mumps and rubella) vaccine led to some parents deciding not to immunise their children and so measles returned. The World Health Organisation states that a vaccination rate of 95% is necessary to guarantee protection of the population. In Britain, the rate has fallen to 88.4%.
"All nutritionists learn about rickets, but it's taught that it's pretty much a Third World problem," says Sarah Schenker of the British Nutrition Foundation. This disorder - the result of vitamin D deficiency which causes growing bones to weaken and bend - was thought to have been eliminated in the 50s. Professor Barbara Mawer of the Manchester Royal Infirmary is one expert who has noted its return. She has seen around 30 cases in the past two years and believes that, nationally, there may be hundreds. Asian children are thought to be most at risk: vegetarian diets could be partly to blame (vitamin D occurs naturally only in animal products, although it is, by law, added to margarine), as could dress codes which hide the skin from sunlight, a crucial source of vitamin D. "Our advice is to make sure that you get at least half an hour of daily exposure, at least on the face, hands and arms," says Schenker. "It's quite worrying to think that children might not be getting even that. If we're developing into a nation that simply sits inside, it is bound to have detrimental effects."
A survey by the public health laboratory service (PHLS) of medical professionals has placed TB fifth on the list of health priorities in the UK today, above E coli and hepatitis. "We do see cases and the numbers are rising," says Marjorie Monnickendam of the PHLS. "It became less common, so people don't think that TB could be a possible explanation of their symptoms." Some of these, particularly a persistent cough, can be misdiagnosed as a more common complaint, such as asthma. Between 1948 and 1987, TB cases dropped tenfold; since, the decline has stopped and numbers are rising: from 5,204 reported cases in 1990, to 6,144 last year, killing around 400. Around 70% of children are vaccinated, but in the mid-90s many escaped the needle due to a lack of BCG vaccine. As the TB bacterium can survive in the body for years before stress - caused by homelessness, age or illness, for example - activates it, a decline in vaccination levels could be just what the germ has been waiting for.
Tetanus can never be eradicated. The only effective guard against the disease, which attacks the central nervous system causing painful muscular contractions and lockjaw, is immunisation. Tetanus jabs, along with those for diptheria, pertussis (whooping cough), polio and meningococcal type C, are given to babies from the age of two months, and are - or should be - reinforced with booster injections every 10 years. Three cases of tetanus were reported to the PHLS last year.
Earlier this month, however, 10-year-old Tyla Green was admitted to hospital with tetanus, the first child in Britain to contract the disease for more than a decade. "It's very rare," says Monnickendam. "We don't see very many cases, and most of those tend to be in elderly people who were not vaccinated when they were younger." Ninety-six percent of children are now immunised thanks to widespread vaccination programmes, but then so was Tyla Green.
Ten years ago, in England and Wales, there were two reported cases of diphtheria, which was supposed to have been "conquered" after mass immunisation began 60 years ago. By last year, there were 23. Time to panic? No, says Monnickendam. "Diphtheria is basically a throat infection, and can produce toxins which damage the heart and nerves. But many [diphtheria] bugs don't produce these toxins." In 1998, for example, of 23 recorded cases, 21 were non-toxic, a variant thought to account for the steady increase in cases since 1992.
The number of reported cases of pertussis, to give it its technical name, has fallen from 15,286 in 1990 to 1,139 last year. The fatality ratio, though, has crept up from 0.05 deaths per 100 notifications in 1990, to 0.25 per 100 by the end of the decade. So why has it become more dangerous? Monnickendam says that it is most serious under six months and most of those who die have not been immunised. Some doctors believe that official figures do not reflect the prevalence of whooping cough: one 1997 study in a large suburban practice identified enough cases to indicate a nationwide rate of 330 per 100,000 people; the official rate is fewer than four per 100,000.
Another study in 1996 suggested that as many as two-thirds of whooping cough cases go unreported.