CIESIN Reproduced, with permission, from:


Division of Epidemiological Surveillance

and Health Situation and Trend Assessment

World Health Organization, Geneva, 1992


Acquired immunodeficiency syndrome (AIDS) [1]

It is currently estimated that by 1992, cumulatively about 2 million cases of AIDS had occurred worldwide (of which 1.5 million in adults) and a cumulative total of 450,000 cases of AIDS had been reported to WHO from 153 countries worldwide. Such global data remain highly distorted, for three main reasons. Firstly, there are wide intercountry and interregional differences in the completeness of AIDS case detection and reporting, as well as in the delay in reporting cases to national authorities and then to WHO. Secondly, reporting of AIDS cases to public health authorities, and recognition of AIDS as an important public health problem, have occurred at different times in different countries. Finally, paediatric AIDS remains substantially underrecognized and underreported, because of difficulties in establishing the diagnosis of HIV infection in infancy, as well as overlapping clinical features with the other severe diseases of childhood.

10-12 million people were thought to have become infected with HIV worldwide as of early 1992. Around 90% of these are thought to be in sub-Saharan Africa; about half of the remaining HIV-infected individuals are thought to be in Europe and Northern America. The number of persons infected with HIV is increasing rapidly in Latin America and in South and South-East Asia.

By 1992, an estimated 1.6 million HIV infections may have occurred in Oceania, North America and Western Europe. Over 250,000 AIDS cases have been reported from Oceania, North America and Western Europe, but close to 350,000 or more cases may have occurred by 1992.

Estimates of total HIV infections are difficult to make for Latin America and the Caribbean because of the relatively limited data available, but as of 1992 the cumulative total is estimated to be over 1 million. The total number of adult AIDS cases is estimated to be about 150,000.

By 1987, about 2.5 million HIV infections are estimated to have occurred in sub-Saharan Africa. As of early 1992, the cumulative total in adults may conservatively be estimated at more than 6.5 million. It is estimated that about 750,000 HIV-infected infants had been born in Africa by 1992, and the projected total by the end of the 1990s is 4-8 million.

The projections for HIV-infected infants are based on a perinatal transmission rate of about 30%. This rate may increase with time, but it nevertheless suggests that up to 70% of infants of HIV-infected mothers will be born uninfected. These uninfected infants will constitute a growing group of potential orphans, since most of their HIV-infected mothers will die of AIDS within 5-10 years of their birth. During the 1990s, as many as 10 million children under 10 may be orphaned as a result of maternal AIDS in the region.

Projected infant and child deaths from AIDS may increase child mortality rates by as much as 50% in much of sub-Saharan Africa during the 1980s. In many countries this would wipe out the gains in child survival achieved over the past two decades.

During the 1990s, the impact of AIDS will be greatest in large urban areas of sub-Saharan Africa, especially in East and Central Africa. In such cities, AIDS deaths in young children and in those aged 15-49 may well reduce expected population growth by more than 30%. The adult mortality rate may more than triple. However, the population in these countries is expected to continue growing during the 1990s.

As of early 1992, a conservative estimate of HIV infections in South and South-East Asia is over 1 million. The limited data available indicate that the fewer than 700 AIDS cases reported to date represent reasonably accurately the current status of AIDS in East Asia and the Pacific. A large proportion of these are in persons with haemophilia who became infected through HIV-infected blood products in the early to mid-1980s. However, the numbers of HIV-infected persons are estimated to be at least in the tens of thousands, and the numbers of AIDS cases are thus expected to increase markedly during the 1990s.

Although data from only a few studies are available to WHO, they suggest that extensive spread of HIV has begun in some parts of North Africa and the Middle East. Approximately 1,000 cases of AIDS and, in addition, more than 3,000 HIV infections have now been officially reported. It is estimated that by 1992 there may have been about 50,000 HIV infections in this region.

It is currently projected that for the year 2000, there will be a cumulative total of 30-40 million HIV infections in men, women and children, of which more than 90% will be in the developing countries. The projected cumulative total of adult AIDS cases is close to 10 million, of which almost 90% will be in the developing countries. There will be 10 million or more children under 10 orphaned as a result of AIDS, primarily in developing countries.

1. Based on WHO programme information.

Endemic treponematoses 1]

During the 1950s and 1960s, an estimated 50 million cases, mostly children and their contacts, were treated in 46 countries. However, small reservoirs of yaws and endemic syphilis remained undetected or undertreated and in the absence of adequate surveillance have led to a resurgence and spread of clinical cases. Renewed control efforts reduced the prevalence of active cases to below 0.5% in most affected countries. Recent surveys have found a prevalence rate of 5-15% in some areas of Africa.

Today they are an estimated 2 million cases of yaws, endemic syphilis and pinta worldwide, 75% of them in children. More than 50 million additional children are at risk of becoming infected.

1. Based on WHO programme information.

Sexually transmitted diseases [1]

Reliable data on worldwide incidence are not available. Minimal estimates of yearly incidence for four major bacterial STD are: gonorrhoea, 25 million cases; genital chlamydial infections, 50 million cases; infectious syphilis, 3.5 million cases; chancroid, 2 million cases. For viral STD, due to the importance of asymptomatic infections, incidence can only be very roughly estimated: genital herpes, 20 million cases; genital human papillomavirus infection, 30 million cases. Trichomoniasis, which is of much less public health importance than the bacterial and viral STD mentioned above, has an estimated annual incidence of 120 million cases.

1. Based on WHO programme information.

Cholera [1]

The seventh recorded cholera pandemic, after 30 years of westward spread from its origins in the Far East, reached the Americas at the beginning of 1991. Following this extension to Latin America in 1991, endemic El Tor cholera is now likely to affect the populations of the disadvantaged areas of Africa, Latin America and Asia for the foreseeable future.

1. Based on WHO programme information.

Diarrhoeal diseases [1]

In 1990, diarrhoea was associated with about 3.2 million deaths in children under 5, down from an estimated 3.4 million in 1985. About 6% of diarrhoea deaths among children occur in association with measles.

It is estimated that currently 50% of diarrhoeal deaths are due to acute watery diarrhoea, 15% are due to dysentery, and 35% are due to persistent diarrhoea. A 50% reduction in diarrhoeal mortality compared with the 1990 level can be achieved by the year 2000.

A child under 5 years in the developing world (excluding China) suffers on average 3 episodes of diarrhoea per year. This results in approximately 1,400 million episodes of diarrhoea per year in these developing countries (where there are estimated to be more than 500 million children under 5).

See also under Oral rehydration therapy for diarrhoea.

1. Based on WHO programme information.

Dracunculiasis [1]

Dracunculiasis (or Guinea-worm disease) occurs in 16 sub-Saharan African countries and 2 countries in Southern Asia. It is estimated that the total number of dracunculiasis cases worldwide is now probably less than 3 million, rather than in the range of 5-10 million cases as estimated in the mid-1980s.

1. Based on WHO programme information.

Filariasis [1]

It is estimated that about 750 million people live in endemic areas of lymphatic filariasis; 76 countries are affected, and 90 million people are infected (70-75 million with Wucheraria bancrofti and about 6 million with Brugia malayi or B. timori).

1. Based on WHO programme information.

Onchocerciasis [1]

Onchocerciasis is endemic in 26 countries in Africa, 2 in the Eastern Mediterranean Region and 6 in Latin America, and 75-80 million people are at risk. In 11 African countries, the number of people infected with Onchocerca volvulus dropped by about 1 million, from about 17.7 million to about 16.7 million, and the number of blind from onchocerciasis from around 330,000 to 295,000.

1. Based on WHO programme information.

Schistosomiasis [l]

About 200 million persons are estimated to be infected, and the total number of people at risk in the world is estimated at 600 million.

1. Based on WHO programme information.

Intestinal parasitic infections [1]

Attempts to derive estimates of the global prevalences of intestinal parasitic infections have had to be made on the basis of meagre data. These tentative figures should do no more than direct attention to the probable scale of parasitic infections in a comparative manner. As general intestinal parasitic infections are more prevalent in children of slums, shanty towns and squatter settlements than in children living in rural areas, for the next century a significant increase in transmission and prevalence is predicted due to urbanization trends if control measures are not taken.

Ancylostomiasis (hookworm infections). It was estimated in 1977-78 that there were 700-900 million infected, 1.5 million cases of disease and 50,000-60,000 deaths. A tendency of decreasing prevalence rates and incidence of hookworm anaemia in some areas is balanced by population growth, which means that the total number of infected people and cases of disease remain unchanged.

Giardiasis. 200 million people are infected (prevalence), with incidence of 500,000 symptomatic cases per year, but a very low death rate (1977-78). Reported prevalences of Giardia infection range from less than 1% to more than 50% depending on the geographical location of the population and prevailing type of Giardia transmission.

Cryptosporidium infection occurs in both immunocompromised and immunocompetent subjects. In developed countries cryptosporidiosis is reported to develop in 2-10% of AIDS patients. In the general population reported detection rates have varied from <1% to >30% of stools examined and are generally higher in young children and in less developed areas. In developing countries most people acquire the infection early, where it is especially associated with episodes of persistent diarrhoea.

Entamoeba histolytica infection. It was estimated in 1984 that 500 million people were infected, of whom 40-50 million (10%) developed clinical amoebiasis each year, resulting in 40,000 - 100,000 deaths.

Ascariasis. It was estimated in 1977-1978 that there were 800-1,000 million cases of infection, and 1 million cases of disease with 20,000 deaths. A recent review estimated the prevalence of ascariasis in Africa in the decade 1974-1983 to be about 32%.

Trichuriasis. It was estimated in 1977-1978 that there were 500 million cases of infection and 100,000 cases of this non-fatal disease.

1. Based on WHO programme information.

Leptospirosis [1]

Leptospirosis is found worldwide and most of the cases are diagnosed in professionally exposed groups such as slaughterhouse workers, veterinarians, livestock breeders, sewer workers, and in some countries in groups representing a large part of the total population, i.e. paddy-field and sugar-cane workers. Cases are also associated with recreational activities such as swimming and fishing.

In countries where rice cultivation is common, large numbers of farmers involved in watery rice paddy field work throughout the year are affected with leptospirosis. Prevalence in endemic areas in these countries can range from 4 to 100 per 100,000 population.

1. Based on WHO programme information.

Alveolar echinococcosis [1]

Alveolar echinococcosis is observed in Central Europe, North America and Asia. In the central part of Europe, alveolar echinococcosis has been recorded since the XIXth century, although incidence observed remained 20-30 cases annually.

In North America, affected areas had an average incidence of 33 per 100,000 population in 1985-1989, while in parts of Asia in the 1980s, average incidence was 10 per 100,000. In the most intense foci incidence was reported to rise to 170 per 100,000.

1. Based on WHO programme information.

Trypanosomiasis [1]

Recent estimates suggest that some 50 million people in 36 countries are at risk of acquiring African trypanosomiasis (sleeping sickness). Although only the relatively small number of 20,000 new patients is reported annually, this figure is certainly an underestimate. With a case-fatality rate of 100% and the constant risk of epidemics, it represents a serious health problem.

As regards Chagas disease (American trypanosomiasis), some 90 million people in Central and South America are exposed to risk according to recent estimates. Based on epidemiological studies, the number of infected people in Latin America is estimated to be of the order of 15-18 million. Of infected individuals, approximately 25% develop chronic Chagas cardiopathy. According to recent evidence, chronic Chagas disease may be responsible in some areas for up to 10% of deaths among the adult population.

1. Based on WHO programme information.

Toxoplasmosis [1]

Evidence from countries with relatively reliable statistics shows that about 3 out of every 1,000 pregnancies are affected by toxoplasmosis, resulting in fetal deaths, perinatal morbidity or chronic infections.

1. Based on WHO programme information.

Leishmaniasis [1]

Currently, the leishmaniases prevalent in four continents are considered to be endemic in 82 countries (10 developed and 72 developing, of which 13 least developed). The large number of endemic countries illustrates the global importance of the problem, but the situation is far more severe in a few countries. A common estimate of the worldwide incidence per year is 600,000 newly reported clinical cases. Overall prevalence is 12 million cases and the estimated population at risk is about 350 million. There is a great difference between the number of cases actually occurring and the number officially reported.

1. Based on WHO programme information.

Malaria [1]

Of a total world population of about 5,300 million people (1990), about 3,100 million (59%) live in areas free of malaria (it never existed, disappeared or was eliminated by antimalaria campaigns and the malaria-free situation has been maintained). About 1,700 million people (32%) live in areas where endemic malaria was considerably reduced or even eliminated, but there has been a resurgence of transmission and the situation is currently stable or deteriorating. These areas include zones with the most severe malaria problems which developed following major ecological or social changes; these zones comprise only about 1% of the world population. Areas where endemic malaria remains basically unchanged and no national antimalaria programmes were ever implemented are inhabited by roughly 500 million people (9%), mainly in tropical Africa.

Malaria is endemic in some 90 countries or areas and small malaria foci are reported in 8 others. Falciparum malaria does not occur or represents less than 1% of the cases in 13 countries. Of about 2,200 million people considered at risk, 280 million are believed to be infected. Clinical cases are estimated at nearly 120 million per year and mortality at 1-2 million per year. About three-quarters of these deaths are estimated to occur among children under 5.

These figures are crude estimates because accurate information on the global incidence of malaria is difficult to obtain. Reporting is particularly fragmentary and irregular in areas known to be highly endemic; for example, countries in tropical Africa, which are estimated to have more than 80% of all clinical cases and more than 90% of all parasite carriers, report only 4-7% of the estimated global number.

Excluding Africa, 5 million cases were reported to WHO in 1990; 95% of all cases reported originated in only 25 of the some 90 countries or areas with endemic malaria.

Africa, south of the Sahara, with a population of approximately 515 million people, experiences the highest levels of endemicity of malaria in the world. Malaria ranks among the leading causes of morbidity and mortality. About 20-30% of outpatient visits to rural health centres and hospitals relate to malaria, while about 10% of all hospital admissions are due to malaria. Between 12 and 22 million clinical cases of malaria are reported annually to WHO, the majority being falciparum infections. Some 100 million clinical malaria cases are estimated to occur in Africa every year. The prevalence of infection is considered to be in the order of 275 million parasite carriers.

1. Based on WHO programme information.

Dengue and dengue haemorrhagic fever [1]

Of all the arthropod-borne viral diseases, dengue fever is the most common. Estimates of the extent of the disease are in the range of 30-60 million infections each year, and an undetermined percentage of these will show clinical disease. Dengue has been steadily spreading and now occurs in most of the tropical world. Over half of WHO Member States, representing a total population of 2,000 million, are threatened by dengue. During the 1980s the haemorrhagic form of dengue spread to areas where formerly only classical dengue had been reported (Americas, the Pacific).

1. Based on WHO programme information.

Yellow fever [1]

The years 1988, 1989 and 1990 were an extraordinarily active period for yellow fever. The worldwide total of 8,685 yellow fever cases for 1988-1990 represents the greatest number of cases reported to WHO since 1948. However, only a small percentage of yellow fever cases are actually reported. WHO estimates that in 1990 there were at least 200,000 cases and 30,000 deaths due to yellow fever worldwide.

In Africa, 8,133 yellow fever cases and 2,194 yellow fever deaths were reported for 1988-1990. The recent pattern of yellow fever epidemics in Africa shows that children have been predominantly infected.

In South America, yellow fever is predominantly a disease of adult forest workers. For 1988-1990, a total of 552 yellow fever cases and 449 deaths were reported from South America.

4,295 cases were reported to WHO for 1990 (346 deaths). Of these, 4,205 cases occurred in Africa (277 deaths) and the remainder in South America.

1. Based on WHO programme information.

Japanese encephalitis [1]

Japanese encephalitis is a serious public health problem in many Asian countries, where 30,000 - 40,000 cases are reported annually.

Clinically apparent infections occur in about 1 of 300 infections. 10-40% of clinical cases die and 10-20% of the survivors will suffer severe neurological sequelae.

1. Based on WHO programme information.

Bacterial enteric zoonoses [1]

Foodborne infections and intoxications due to zoonotic agents in food of animal origin have become widespread in large parts of the world. For example, at least 1 million persons each in Northern America, Western and Eastern Europe are affected each year by this type of infection. Different phage types of Salmonella enteritidishave become apparent as invasive, egg-transmitted agents of an increasing proportion of human salmonellosis in these areas during the last decade. However, the number of human isolates of S. enteritidis also appears to be increasing in South America, and probably in Africa as well. Outbreaks of disease and infection caused by Escherichia coli and some other related serovars are increasingly reported. These affections are characterized by high morbidity and case-fatality rates, especially among children and the elderly.

1. Based on WHO programme information.

Brucellosis [1]

86 out of 175 countries (49.1%), representing a population of 2.7 billion in all regions, are affected by animal brucellosis and human brucellosis is therefore widespread. Eastern Mediterranean countries have experienced an increase in the number of cases in 1985-1990. In the region as a whole, 82,772 cases were reported in 1988, as compared to 2,873 in 1985. This represented an average incidence of 18.9 per 100,000 in 1988.

1. Based on WHO programme information.

Leprosy [1]

The total number of registered cases in the world at the beginning of 1992 was 3.1 million, giving a global prevalence rate of 5.7 patients per 10,000 population. The estimated number of cases in the world for 1991 was 5.5 million. The total number of newly detected cases was 584,412 with a global detection rate of 1.1 cases per 10,000 population. South-East Asia has the greatest leprosy problem, with over 70% of the total number of cases in the world; the regional registered prevalence and detection rates of 16.3 and 3.7 patients per 10,000 population respectively, are also the highest when compared with other regions. The magnitude of the problem in Africa and the Americas is much less, while Europe, the Middle East, and East Asia together have only 5% of the total number of registered cases. Over the years, there has been a steady reduction in the number of registered cases from 5.4 million in 1985 to 3.1 million in 1990, representing a decrease of 42.5%.

1. Based on WHO programme information.

Tuberculosis [1]

Tuberculosis is one of the most widespread infections; approximately 1,700 million people, or one-third of the world's population, are infected and at a probably lifelong risk of developing the disease. In 1992, 8.4 million new cases will occur, of which 8.1 million (96%) in developing countries. Of these, 2.7 million cases will be in the Western Pacific Region, 2.6 million in the South-East Asia Region and 1.5 million in the African Region, where the present incidence is highest (276 cases per 100,000 population). Tuberculosis will be responsible for over 3 million deaths (of which 400,000-500,000 will be among children and adolescents under 15 years old).

Since 1985 the incidence of tuberculosis has started to increase in some industrialized countries and in many sub-Saharan and Caribbean countries, mainly as a result of the association of tuberculosis and HIV infection. HIV infection is by far the highest risk factor for tuberculosis infection to progress to disease: at least 30% of those infected with both tuberculosis and HIV, but probably an even higher proportion, will develop tuberculosis. By the end of 1991 already close to 4 million people were dually infected, of which 3.1 million in sub-Saharan countries. In the industrialized countries approximately 1.5 million people were infected with HIV, but the prevalence of tuberculosis infection among them was much lower than in Africa so that the number of dually infected persons was relatively low and, moreover, concentrated in certain particular risk groups, notably intravenous drug users.

Since the HIV epidemic is still in its ascending phase and tuberculosis normally does not develop until several years after HIV infection, and since moreover the increase in incidence will entail an increase in transmission of tuberculosis infection, the situation must be expected to worsen dramatically unless control measures are taken forthwith. Asian countries should be on the alert; in many of these countries tuberculosis infection is even more common than in Africa and HIV infection is making inroads.

1. Based on WHO programme information.

Acute respiratory infections [1]

In 1990, there were 4.3 million deaths from ARI, in children under 5 in developing countries including 800,000 neonatal pneumonia, 480,000 post-measles pneumonia and 260,000 ARI-related pertussis deaths.

The annual incidence of pneumonia in children under 5 in developing countries ranges from 10% to 20%.

1. Based on WHO programme information.

Plague [1]

In 1990, 1,250 cases of human plague recorded in 12 countries were notified to WHO; 137 patients died. These figures exceed the corresponding figures for 1989 (770 cases, 104 deaths) and the average figures per year (855 cases, 98 deaths) for the previous 10 years (1980-1989). In 1990, the global case-fatality rate was 10.7% as compared with 13.5% in 1989 and an average of 11.5% per year in the previous 10 years.

1. Based on WHO programme information.

Meningococcal meningitis [1]

Meningococcal meningitis occurs in all parts of the world. In the endemic form it causes sporadic cases or small clusters. In regions of hot dry climates, epidemics which may last 2-3 years occur every 5-8 years. Without epidemics, 1 million cases of bacterial meningitis are estimated to occur every year and at least 200,000 of them die. About 300,000 of these cases and 30,000 deaths are due to meningococcal meningitis. In epidemic years the number of meningococcal meningitis cases may double to 600,000 cases or more with 60,000 or more deaths. In the 1980s an epidemic wave of meningococcal meningitis spread over vast territories in Asia and Africa.

1. Based on WHO programme information.

EPI target diseases [1]

It is estimated that currently about 1.8 million children die each year of vaccine preventable diseases. Estimates for 1991 were as follows:

Neonatal tetanus. 350,000 deaths in the 25 largest developing countries and 83,000 in other developing countries, with a total of 433,000.

Measles. 718,000 deaths in the 25 largest developing countries and 272,000 in other developing countries, with a total of 990,000.

Pertussis. 253,000 deaths in the 25 largest developing countries and 96,000 in other developing countries, with a total of 349,000.

Poliomyelitis. 93,000 cases in infants in the 25 largest developing countries and 32,000 in other developing countries, with a total of 125,000.

1. Based on WHO programme information.

Foodborne diseases [1]

For estimates concerning specific diseases which frequently are or may be foodborne see under Brucellosis, Cholera, Diarrhoeal diseases, Intestinal parasitic infections, and Toxoplasmosis. It should be noted also that even in favourable circumstances only a small fraction of foodborne diseases are recognized and reported. Studies suggest that the ratio of actual to reported cases varies between 25:1 and 100:1.

It is estimated that in possibly up to 70% of cases, food is the vehicle for transmission of diarrhoeal diseases. Also of importance are intoxications due to Bacillus cereus, Clostridium perfringens, Staphyloccocus aureus and infections due to pathogenic Escherichia coli. The latter account for up to 25% of all diarrhoeal episodes and are often related to contaminated weaning foods. Information available from some Latin American countries indicates that many of the foodborne diseases (excluding cholera which has recently devastated the region) have increased by up to 100% (or more), within a few years.

Similarly, many industrialized countries in Europe, North America and Oceania have experienced a succession of major epidemics of foodborne diseases. The current incidence of more than 1,200 reported cases per million inhabitants, as an average for Europe, is about 3 times higher than was recorded in 1984. Poultry has been implicated in many outbreaks, and in some countries investigations have shown that up to 100% of poultry may be contaminated with foodborne pathogens such as salmonella and/or Campylobacter.

Travellers are especially at risk from foodborne diseases. It is estimated that 20-50% of the approximately 400 million travellers who annually cross international borders may suffer from foodborne diseases. With the growing tourism industry, it is expected that the number of foodborne diseases will increase.

1. Based on WHO programme information.

Rabies [1]

Wildlife rabies is present in large areas of the northern hemisphere in many different animal species (e.g. fox, skunk, raccoon, raccoon dog, mongoose, etc.). Although only a small number of human deaths are reported there, rabies remains a permanent public health hazard and represents a major obstacle to the free movements of people and their pets.

Dog rabies is still present in 87 countries and territories (with a total population of 2.4 billion) and where about 35,000 human deaths due to rabies are estimated to occur each year. In these areas a total of 5 million persons would require rabies post-exposure treatment in order to prevent 80% of these deaths. Total current annual expenses related to the prevention and control of the disease in humans and animals is estimated to be in the range of US$ 150 - 250 million. Comprehensive programmes for the control of the disease in dogs have been shown to cost 25-52% less than a programme for improved post-exposure delivery in human beings.

1. Based on WHO programme information.

Hepatitis B [1]

More than 2 billion people have been infected with the hepatitis B virus (HBV) globally; this figure includes some 325 million chronically infected carriers of the virus. Three-quarters of the world's population live in areas where there are moderate to highly endemic levels of infection. In developing countries, HBV infection usually occurs during childhood, while in developed countries it usually occurs among adult members of high-risk groups defined by lifestyle or occupation. HBV infection is directly related to 1-2 million deaths per year. Although acute hepatitis B is an important disease, most of the morbidity and mortality occurs in chronic carriers, approximately one-quarter of whom will die from chronic active hepatitis, cirrhosis or primary liver cancer. Primary liver cancer is a leading cause of cancer death in males in most of sub-Saharan Africa and much of East and South-East Asia and the Pacific Region.

By the year 2000, applying the current prevalence of carriers onto projected year 2000 population data, it is estimated that there will be 400 million HBV carriers in the world if HB vaccine is not widely used.

1. Based on WHO programme information.

Trachoma [1]

Trachoma is still one of the major causes of blindness in the world today, with an estimated 69 million blind and around 500 million people living in areas with endemic blinding trachoma.

1. Based on WHO programme information.