Disease Patterns

The foregoing sketch suggests a distinctive ecological disease pattern for the Middle East and North Africa. Pastoralism and the farmers' reliance on animals for transport, power, fertilizer, and dung fuel have made these occupational groups, living in close proximity to their livestock, vulnerable to zoonoses and to insect-borne diseases, some of which infest domestic or wild animals. Another important disease complex has developed out of the necessity for irrigation: the widespread incidence of parasitism due to favorable conditions for proliferation of the insect carrier and an intermediate host where required. At an agricultural conference in 1944, it was reported that expanding irrigation in one area of Egypt had raised the incidence of both malaria and schistosomiasis from 5 to 45 or even 75 percent of the population in that area (Fisher 1971). This survey, therefore, will begin with those ailments most closely related to the rural environment: arthropod-borne diseases and parasitic infestations. Next it shall consider the "crowd diseases," most characteristic of urban societies, but also found in crowded villages and oases. Last it shall sketch the diseases caused by nutritional deficiencies among rural and city people. Within those categories, diseases are listed in descending order of their prevalence or importance as death- or disability-threatening experiences.

Major Arthropod-Borne Diseases Because the many species of anopheline mosquitoes have adapted to breeding in the widest variety of hydrological conditions - from swamps and stagnant irrigation pools to fast-moving mountain streams, and from freshwater springs to brackish marshland - they are found throughout the region except in stretches of desert lacking any surface collection of water. From 9 to 19 species of anopheline mosquitoes exist in each Middle Eastern and North African country, of which 3 or 4 have been identified as vectors of malaria.

Although mosquitoes cannot survive dry, hot weather, their proliferation in oases in Libya's Fezzan Desert and in the Arabian Peninsula demonstrates their tenacity. One species of Anopheles endemic in southwestern Arabia has caused recurrent epidemics of malaria under favorable rainfall conditions. The last such epidemic was reported in 1950-1, when this species spread inland from Jidda along the road to Mecca, carried by the increased traffic of the Muslims' annual pilgrimage.

Malaria has been reported in all the countries of the Middle East and North Africa. Since World War II the World Health Organization (WHO) has carried out extensive mosquito eradication projects. Nonetheless, malaria continues to break out periodically, and in 1950 a public health survey in Morocco reported that it was still the most prevalent disease in the country (Simmons et al. 1954; Nosologie maro-caine 1955; Kanter 1967; Benenson 1975).

The Aedes Aegypti mosquito that transmits dengue fever also is a potential vector of yellow fever, but that infection has not been reported in the Middle East and North Africa. Dengue is endemic in the eastern Mediterranean area but has not been observed at heights exceeding 600 meters (2,000 feet) and has been largely confined to coastal areas. Most countries in the Middle East have sporadic outbreaks of dengue fever, and a few cases are reported in Libya every year; whereas in Morocco, Algeria, and Tunisia, the infection has remained only a potential threat (Simmons et al. 1954; Kanter 1967; Benenson 1975).

Because early symptoms of Bancroftian filariasis may be simply fever and lymphadenitis, the disease was not reported historically until prolonged and repeated infection caused elephantiasis of the limbs or outer genitalia. Today, although the most common mosquito vector of filariasis is abundant throughout the region, the threat of the disease has remained potential. In Lebanon, filariasis appears occasionally. There is one focus of infection in the southwestern Arabian Peninsula and another in Egypt, where the mosquito vector proliferates in numerous brackish wells in Rosetta (Simmons et al. 1954; Benenson 1975).

Bubonic plague is transmitted by the bite of an infective flea, usually Xenopsylla cheopis, and marked by acute lymphadenitis forming buboes, at the site of the infection; septicemic plague occurs in severe and advanced bubonic plague, causing petechial hemorrhages; pneumonic plague, the most infectious and fatal form, is airborne, spread by inhalation of exhaled droplets from infected patients.

The Middle East and North Africa suffered se verely in the sixth-century plague of Justinian, and repeatedly thereafter. Because Procopius had placed the origin of that pandemic in Egypt, the Nile Valley became identified in Europe's popular and professional imagination as "the cradle of plague." However, the recurring epidemics of bubonic plague in this region were initially imported. Infected fleas on rats infesting the holds of cargo ships transmitted the infection to domestic rats in Mediterranean port cities and established endemic loci for the disease. Only the coast is naturally vulnerable to plague. Inland areas are too hot or too cold, and above all too dry to be susceptible to enzootic plague. However, irrigation systems acted as networks for transmitting infective fleas by providing harborage for rats in the embankments of canals. Epidemics flared periodically whenever optimum weather conditions - high humidity and moderate temperatures - coincided with an adequate rat-flea density. After the adoption of quarantine measures in the southern and eastern Mediterranean in the nineteenth century, followed by the discovery of the rat-flea nexus, most areas of the world including the Middle East and North Africa managed to bring plague under control until the epidemic of 1894, which originated in northern China.

Plague, however, continues to be a potential danger in the Middle East and North Africa. A reservoir of sylvatic (wild rodent) plague in the mountains of southwestern Arabia and the Kurdish highlands, shared by Iran, Iraq, and Turkey, may spread infection by contact with domestic rats. In Libya sporadic cases transmitted by steppe rodent fleas broke out almost annually from the time of World War I until 1940. In Morocco as well, plague recurred sporadically until 1946, and it was also reported in Tunisia, Algeria, and Egypt up to the early 1950s (Hirsch 1883; Hirst 1953; Pollitzer 1954; Simmons et al. 1954; Nosologie marocaine 1955; Kanter 1967; Benenson 1975; Gallagher 1983).

Characteristic of colder climates, typhus is not common in this region and has occurred chiefly during the winter among nomads who wear the same heavy clothing day and night. The human body's humid microclimate provides a favorable environment for the louse to deposit eggs (nits) that hatch into young lice in a few days. Warm dry weather is unfavorable for breeding because humans dress more lightly, exposing the lice to high temperatures and sunlight. Displacement of people and crowding during World War II contributed to a series of epidemic outbreaks of typhus in North Africa, but delousing campaigns appeared to eliminate the dis ease. Nonetheless, occasional outbreaks have been reported in Iran, Iraq, Syria, and Jordan, from congested villages and town quarters as well as from refugee camps (Rodenwaldt 1952; Simmons et al. 1954; Nosologic marocaine 1955; Kanter 1967; Benenson 1975).

Other Arthropod-Borne Diseases

Although foci for endemic tick-borne relapsing fever (alternating febrile and afebrile periods) exist throughout the region, the disease is rare. Epidemic louse-borne relapsing fever is more common; between 1942 and 1945 a series of epidemics spread throughout North Africa from Morocco through Egypt and extended into Turkey, but it has occurred only sporadically since then. Boutonneuse fever is a mild to moderately severe febrile illness widely distributed in countries adjacent to the Mediterranean, Caspian, and Black seas. The disease, which is transmitted by the bite of an infected dog tick, occurs occasionally in Morocco, Algeria, Tunisia, Libya, and Turkey, and rarely in Israel and Lebanon. Also, another tick-borne disease, tularemia, a plaguelike infection of wild and domestic animals, especially rodents and rabbits, is found only in Turkey (Rodenwaldt 1952; Simmons et al. 1954; Benenson 1975).

Of the three types of leishmaniasis, only cutaneous leishmaniasis (Leishmania tropica) is common in the Middle East and North Africa. In 1756 Patrick Russell named the affliction the "Aleppo boil," and today it is also known as "Baghdad boil" in Iraq and "Jericho boil" in Jordan. In Israel it is most common in the Haifa area. It also occurs sporadically in the Arabian Peninsula and in southeastern Turkey, where it is known as "Urfa sore." In North Africa cutaneous leishmaniasis is endemic and prevalent in Algeria and Morocco, widespread in Tunisia and Egypt, but rare in Libya (Russell 1794; Rodenwaldt 1952; Omran 1961; Kanter 1967; Benenson 1975).

Kala-azar, or visceral leishmaniasis, is a chronic systemic infection disease characterized by fever, enlargement of the liver and spleen, anemia, and progressive emaciation and weakness. Untreated, it is a highly fatal disease. Although the vectors of kala-azar are not common in this region, three species of sandflies are suspected of transmitting visceral leishmaniasis that appears sporadically in the northern and western coastal provinces of Turkey, and the littoral of Algeria and Morocco (Simmons et al. 1954; Benenson 1975).

Sandfly fever or pappataci fever (phlebotomus fever) is a viral 3- or 4-day fever that resembles influenza and is carried by the same phlebotome -Phlebotomus papatasii - transmits cutaneous leishmaniasis. Sandfly fever reportedly is endemic in Syria, Lebanon, Israel, Iraq, Iran, and sporadic in Jordan and Saudi Arabia (Simmons et al. 1954; Benenson 1975).

Finally, numerous species of flies are abundant throughout the Middle East and North Africa; among the most common of these are species of the Muscidae family, thought to be implicated in the mechanical transmission of intestinal and eye infections. For example, gastroenteritis causing infantile diarrhea and dehydration, which has been held responsible for more than half the infant deaths in Egypt, shows a striking peak of incidence during the hot, dry, fly season (Labib 1971). Several species cause myiasis in livestock and occasionally in humans, but cases of these invasions are rare (Simmons et al. 1954).

Helminth-Transmitted Diseases Of the four species of blood flukes infecting humans — Schistosoma haematobium, Schistosoma mansoni, Schistosoma intercalatum, and Schistosoma japonicum - only the first two are endemic in the Middle East and North Africa. Persistence of the disease depends upon the presence of freshwater snails as the intermediate hosts.

The evolution of schistosomiasis probably occurred during the period when human populations were shifting from hunter-gathering economies to societies based on settled agriculture. Parasitism requires a stable relationship between host and parasite, such as is available in settlements close to slow-moving water in which snail hosts of the disease dwell. Vesical or urinary schistosomiasis probably existed in both ancient Mesopotamia and Egypt. Babylonian inscriptions and Egyptian papyri (Ebers, Kahun) refer to hematuria and prescribe remedies. In 1910 Marc Ruffer discovered ova in Egyptian mummies dating from 1200 B.C., and J. V. Kinnear-Wilson considers the finding of shells of the most common host snail, Bulinus truncatus, in the mud brick walls of Babylon evidence that S. haematobium was the cause of hematuria described in Babylonian texts. French soldiers suffered with hematuria during the occupation of Egypt in 1798-1801, but the causative parasite was not identified until 1851 when Theodor Bilharz recovered adult worms from the portal system during an autopsy in Cairo. The life cycles of the intermediate molluscan hosts were demonstrated early in the twentieth century.

Studies and clinical records between 1931 and 1961 reported schistosomiasis in all the countries of the Middle East and North Africa. However, because of prevailing desert conditions, North Africa, except for Egypt, has not harbored parasites that require surface water or moist soil for survival. A notable exception is the Fezzan in Libya, where in some oases with shallow wells, up to 86 percent of the inhabitants have been infected. However, outside a relatively small radius the groundwater available to oases has too high a salt content to support the host snail. The highest incidence, up to 100 percent in some villages, has occurred in Iraq and especially in Egypt where the inhabitants of the Nile Valley have maintained irrigation systems for millennia.

The widespread species has been S. haematobium; infection with S. mansoni has appeared only in Egypt and among Yemeni and Iraqi immigrants to Israel, although the host snail exists in the Arabian Peninsula and North Africa (Ruffer 1910; Simmons et al. 1954; Nosologie marocaine 1955; Malek 1961; Farooq 1964; Kanter 1967; Kinnear-Wilson 1967; Benenson 1975; Sandbach 1976; Sandison 1980).

Ancylostomiasis, or hookworm disease, is probably quite old. A chronic disease of the digestive system described in the Ebers Papyrus of 1550 B.C. has been interpreted as hookworm disease. In 1838 Angelo Dubini discovered a worm that he called Ancy-lostoma duodenale, during autopsies in Egypt, and a colleague found the same parasite during autopsies in 1845, but neither related them to specific diseases. In 1853, Wilhelm Griesinger identified ancylostomiasis as the cause of the endemic anemia, called "Egyptian chlorosis," and observed that 25 percent of the causes of death were traceable to the effects of this infestation.

Ancylostomiasis occurs in all Mediterranean countries, but the Nile Valley has been a particular locus of the infection (Khalil 1932; Simmons et al. 1954; Nosologie marocaine 1955; Benenson 1975).

Ascariasis (infection of the small intestine caused by Ascaris lumbricoides, the large intestinal roundworm) may cause digestive and nutritional disturbances. Pictorial evidence demonstrates the presence of Ascaris in ancient Mesopotamia, and numerous prescriptions for roundworm in the Ebers Papyrus indicate that the ancient Egyptians complained of this parasite as well. In the twentieth century, ascariasis has been most common among school children, who may suffer anemia and eosinophilia from high infestation. Serious complications among children may include bowel obstruction and occasionally death due to the migration of adult worms into liver or gallbladder (Simmons et al. 1954; Kanter 1967; Kinnear-Wilson 1967; Benenson 1975; Sandison 1980).

Other worm-related diseases include trichinosis, which, because of the Muslim and Jewish prohibition against pork, is rare in the Middle East and North Africa, and has been reported only in Lebanon. Taeniasis, an infection with the beef tapeworm, Taenia saginata - causing anorexia, digestive disturbances, abdominal pain, and insomnia - occurs where the larvae are ingested with raw beef. It is particularly frequent among herding peoples whose sheep, cattle, and dogs have a high rate of infection, which may be passed to humans. In Libya, for example, the government hospital at Benghazi reported the existence of the larval form of tapeworm in 20 to 28 percent of the patients annually between 1960 and 1963 (Kanter 1967; Benenson 1975).

Zoonoses

The zoonoses that occur in the Middle East -brucellosis, anthrax, and Q fever - are all occupational diseases of herders, farm workers, veterinarians, abattoir workers, and industrial workers who process hides, wool, or other animal products. Brucellosis, which causes a generalized infection, also known as undulant fever, has been reported in Morocco, Algeria, Tunisia, Iran, Turkey, Syria, and Lebanon. Anthrax, an infectious disease of ruminants, occurs only in Turkey. Q fever rarely infects humans in areas where the disease exists enzo-otically in animals. Occasional cases, however, have been reported in Morocco that were suspected of having been transmitted by tick vectors.

Also increasingly rare is rabies or hydrophobia, an acute, almost invariably fatal viral infection of the central nervous system, transmitted to humans by the bite of a rabid animal. At mid-twentieth century, James Simmons and colleagues (1954) reported rabies in Iran, Syria, and Jordan; however, most countries in this region have controlled rabies by quarantining and licensing pets and by destroying stray animals (Benenson 1975).

Food- and Waterborne Enteric Diseases Acute diarrheal disease in early childhood, most prevalent after weaning, is important in the Middle East and North Africa as in all developing countries. Although it may include specific infections, infantile diarrhea frequently is a clinical syndrome of unidentifiable etiology caused by bacteria, viruses, helminths, or protozoa. Common in areas of poor sanitation and prevailing malnutrition, infant diarrhea may produce as many as 275 attacks per 100 children per year, more than 50 deaths per 1,000 per year in preschool children. Protein—calorie malnutrition is commonly associated with acute diarrheal episodes, which may precipitate kwashiorkor. The highest incidence tends to occur in hot, dry periods, calling for oral rehydration therapy, which has become a high priority program for the WHO in recent years (Simmons et al. 1954; Benenson 1975).

At mid-twentieth century, Simmons reported "dysenteries" for all Middle Eastern countries, but provided no data. All North African countries, including Egypt, reported higher incidence rates for shigellosis then amebiasis, except in Morocco and Libya, where amebiasis was reported more prevalent. Between 1900 and 1950 comparative mortality rates were 8.7 percent for amebic dysentery and 11.8 percent for bacillary dysentery (Rodenwaldt 1952; Simmons et al. 1954; Kanter 1967).

In the Middle East and North Africa, raw fruits and vegetables handled by infected persons are important vehicles of the transmission of typhoid fever, and flies are often vectors for spreading contamination. At mid-twentieth century, the disease was reported in all countries considered in this survey but was reported as rare in Libya (Rodenwaldt 1952; Simmons et al. 1954). Paratyphoid infection due to Salmonella of all groups except S. typhosa is a generalized bacterial enteric infection, clinically similar to but with a lower fatality rate than typhoid fever; it occurs only sporadically in this region.

Cholera did not appear in the Middle East and North Africa until the great pandemics of the nineteenth century that were caused by troop movements in the lands bordering India, Afghanistan, and Iran, and by accelerated sea transport linking Asia with the rest of the world. Six pandemic waves of cholera swept around the world between 1817 and 1923, invading all settled communities in Asia, Africa, Europe, and the Americas. Middle Eastern and North African countries were vulnerable to invasion by the disease because returning Muslim pilgrims carried the infection from the holy cities of Arabia, where it was introduced by Muslims from South Asia. After discovery of the cholera vibrio and the rationalization of quarantine practices, as well as nineteenth-century sanitary reform programs, cholera receded as a major threat. The adoption of efficient control techniques, particularly since the Second World War, has effectively neutralized the danger of dissemination from the Muslim pilgrimage sites. The last major outbreak, which occurred in Egypt in 1947, was due to relaxation of quarantine regulations during the Second World War. However, since 1961 a new strain of cholera, El Tor, has spread extensively from a focus in Sulawesi in Indonesia, through most of Asia and the Middle East into Eastern Europe and Africa, and from North Africa into the Iberian Peninsula and Italy (Hirsch 1883; Simmons et al. 1954; Pollitzer 1959; Kanter 1967; Benenson 1975).

Diseases Transmitted Through the Respiratory Tract

Tuberculosis is widespread in the Middle East in the pulmonary form that was known earlier as phthisis or consumption. Egyptian wall paintings depict humpbacks typical of bone tuberculosis of the spine, known as Pott's disease, and tuberculous bones have been found in tombs dating to 3000 B.C. In modern times, tuberculosis appeared to accompany the rise of industrialization and urbanization in the nineteenth century, succeeding smallpox as the most common affliction in city life. In congested slums tuberculosis assumed epidemic proportions because the infection is transmitted by exposure to the bacilli in airborne droplet nuclei from the sputum of infected persons. In the mid-twentieth century, tuberculosis was reported in all Middle Eastern and North African states. Wartime displacement had caused a steep rise in incidence. In Libya, for example, many uprooted nomads from the Fezzan emigrated to shanty towns on the coast. Because food was scarce and sanitary installations were nonexistent, tuberculosis spread rapidly among these desert people in a severe form that was often fatal. In the 1950s, the WHO and UNICEF supported immunization programs with the result that tuberculosis in the Middle East has become similar to the European type, milder and chronic (Simmons et al. 1954; Nosologie marocaine 1955; Kanter 1967; Benenson 1975; Sandison 1980).

By contrast, pneuomococcal pneumonia was reported to have a significant mid-twentieth-century incidence only in Egypt and Turkey. This may suggest susceptibility among the ill-housed, undernourished poor inhabiting the overcrowded metropolises, as well as an above-average involvement among the coal miners in Turkey (Simmons et al. 1954; Benenson 1975).

Diphtheria typically has been a disease of colder months in temperate zones. It was reported in Egypt, Israel, Jordan, and Iraq in the mid-twentieth century; in Morocco it was identified as one of several diseases that accompanied an influx of Europeans during the Second World War (Simmons et al. 1954; Nosologie marocaine 1955; Benenson 1975).

Meningitis occurs more frequently in children and young adults and more commonly in crowded living conditions. In the mid-twentieth century, meningococcal infection was reported in Turkey, Iraq, Lebanon, and Egypt (Simmons et al. 1954; Benenson 1975).

Smallpox had been a recognized scourge in the Middle East since the sixth-century epidemic struck Ethiopian invaders threatening Mecca. The Islamic scholar-physician Rhazes, in the tenth century, wrote the classic clinical description of the disease, implying that smallpox was very common and endemic to the entire Islamic world from Spain to Persia at that time. It is true that plague overshadowed smallpox in the Mediterranean for several centuries, but the latter remained widespread and continued to claim great numbers of victims until the early nineteenth century when Europeans began introducing Edward Jenner's vaccination into their colonies in Africa and Asia. Nevertheless, although most countries in the Middle East adopted immunization procedures during the nineteenth and early twentieth centuries, smallpox continued to break out in all of them until systematic vaccination campaigns coordinated by WHO eradicated the disease in Libya by 1949 and elsewhere in the region by 1977 (Simmons et al. 1954; Kanter 1967; Hopkins 1983; Fenner et al. 1988).

At about midcentury, measles was recorded only in Egypt, Algeria, and Morocco (Simmons et al. 1944; Benenson 1975).

Diseases Transmitted by Human Contact

Eye diseases are widespread in the Middle East and along the Mediterranean littoral. The most serious, trachoma (earlier called "Egyptian ophthalmia"), is a bacterial infection that progresses clinically from tiny follicles on the eyelid conjunctiva to invasion of the cornea, with scarring and contraction that may lead to deformity of the eyelids and blindness. It is often accompanied by acute bacterial conjunctivitis, a highly contagious form of conjunctivitis, most often caused by the Koch-Weeks bacillus, characterized by inflammation, lacrimation, and irritation, followed by photophobia, purulence, and edema of the eyelids.

Both trachoma and conjunctivitis are transmitted through contact with fingers or articles contaminated by discharges of infected persons. Flies or eye gnats often spread the infection, and lack of water and exposure to dry winds, dust, and sandstorms are thought to aggravate the problem.

Between 1928 and 1936, trachoma morbidity was very high in the Middle East. Egypt was considered the principal focus, where about 90 percent of the population was reported to have suffered trachoma, often combined with acute bacterial conjunctivitis or occasionally gonococcal conjunctivitis. In Syria, Lebanon, and Palestine, about 60 percent of the Arab schoolchildren and 10 percent of the Jewish children from rural areas were infected with trachoma. In Turkey, 60 percent of the population in the southeast steppe area with no forestation was reported affected. In Iran, the highest incidence also was reported in steppe and desert areas near the Persian Gulf and in the interior south of Isfahan. In Iraq, the high incidence of trachoma in Baghdad -80 percent - was attributed to susceptibility to infection from exposure to the loess dust from the Tigris and Euphrates flood areas during the hot dry season.

In Algeria and Morocco about 10 percent, and in Tunisia 40 percent, of the population were infected with trachoma. According to practitioners in Morocco, trachoma was not an independent nosological entity; bacterial conjunctivitis accompanied 80 percent of the cases. In Libya trachoma was most common in the Fezzan oases, where morbidity was estimated at 60 percent of the inhabitants. In the post-World War II migration of desert people to the coastal cities, incidence ranged from 30 percent to 70 percent in the shanty towns outside Tripoli. In spite of preventive programs, the disease was still widespread in 1963, when 4,126 cases were recorded in Tripolitania Province (Rodenwaldt 1952; Simmons et al. 1954; Nosologie marocaine 1955; Kanter 1967; Benenson 1975).

Among North Africans, leprosy was believed to have been imported from the eastern Mediterranean by many peoples. In the ninth century B.C., Phoenicians were blamed for it. Jews driven from Jerusalem in A.D. 135 were believed to have reintroduced it, as were Arab invaders in the eighth century. In addition, it was probably periodically reintroduced by Saharan caravans as well. By mid-twentieth century, however, leprosy had effectively disappeared in North Africa, except among the Berbers, where there were an estimated 8,000 cases, and in Egypt where 30,000 cases were reported (Rodenwaldt 1952; Simmons et al. 1954; Nosologie marocaine 1955; Kanter 1967; Benenson 1975).

Finally, in the mid-twentieth century, scabies was reported in Egypt, Morocco, Iran, Syria, and Jordan, perhaps aggravated by wartime displacement and crowding, as in refugee camps, with consequent lack of water for bathing (Simmons et al. 1954; Benenson 1975).

Venereal Diseases

Because leprosy was often confused with venereal diseases in antiquity, it is not clear when syphilis first appeared in the Middle East and North Africa. Following the Crusades, however, when all Europeans were referred to generically as "Franks," syphilis was associated definitively with Europeans as "il-franji" - that is, the Franks' disease. Gonorrhea reportedly is relatively rare, but occurs fairly frequently as blennorrhea or gonococcal conjunctivitis among infants or very young children. In the mid-twentieth century, nevertheless, venereal diseases were acknowledged public health problems in all the countries of the Middle East and North Africa (Rodenwaldt 1952; Simmons et al. 1954; Kanter 1967; Benenson 1975).

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