Drought and Health Implications in MozambiqueMiguel Aragón, MD; Avertino Barreto, MD, Msc.; Paul R. Epstein, MD, MPH The consequences of drought in Mozambique and the negative health implications to populations include famine, starvation, and epidemics. El Niño (ENSO) events are consistently related to drought in Southern Africa. Current capabilities can provide climate forecasting for Southern Africa with a lead time of up to one year. Thus, Mozambique and Southern African countries should utilize climate forecasting to improve prediction of upcoming anomalous wet or dry periods and to facilitate planning in the fields of agriculture, hydroelectric power, water management, and health. Technological progress in understanding the environment and climate dynamics becomes a matter of development, where poorer countries are disadvantaged. This raises ethical and scientific issues, as well as international policy issues. Governments, UN agencies, scientists, and professionals have an opportunity to improve partnerships among technically advanced nations and the large regions of the globe where the effects of climate and climate changes are exerting severe impacts on populations. It is well understood that drought presents a great potential for human suffering in Africa [1,2]. In southern Africa, drought and flood are the major effects of the variability in temperature and precipitation associated with the El Niño Southern Oscillation (ENSO) phenomenon. In Mozambique, which is regularly affected by droughts, the severe drought during 1991-1992 was related to ENSO and contributed to epidemics and rodent infestation [3]). The objectives of this paper are:
El Niño and Global Warming Global warming and ENSO have been identified as the climatic phenomena responsible for most important weather patterns in the world [4,5,6]. The oceans are the primary memory for the climate system, absorbing heat and circulating it both laterally and vertically. Since 1877, El Niño events [see sidebar, “The El Niño Southern Oscillation”] have occurred every two to seven years (average 4.2 years). Since the mid 1970s, ENSO events have come more often and persisted longer than any previous period [7]. The 1982-83 El Niño was the strongest of the century. Whether or not the increase in El Niño events is due to global warming is a matter of speculation. But there is increasing evidence that deep ocean warming and changes in ocean circulation may be occurring. Deep ocean warming has been reported from subtropical transects in the Atlantic [8], in the Pacific [9], and in the Indian Oceans [10], in the Arctic Tundra and near the poles [11,12]. Ocean warming increases the hydrological cycle [13], thus altering precipitation patterns that affect the timing of disease outbreaks. Several models suggest that El Niño events will increase with global warming [14,15,16,17]. The events of the past two decades are consistent with these projections. In addition, shifts in the ocean “conveyor belt”--which includes the Gulf Stream--may have been historically associated with rapid climate change events, according to ice-core records [18,19,20,21,22,23]. Shifts in the Atlantic ocean temperatures and circulation patterns are now being reported [24]. The world’s oceans may indeed be the main repository (capacitor) for the past century’s global warming; and changes in El Niño patterns may signal instability in the dynamics of the climate system as a whole. One climate phenomenon, drought, is recognized as an extreme event that can generate new explosions of activity in the emergence and distribution of diseases. El Niño is consistently related to drought in Southern Africa. “La Niña,” a cold Pacific Ocean upwelling that often occurs in years subsequent to El Niño events (e.g., in August 1995), creates opposite, “teleconnected,” patterns (1), such as rains and floods in areas that were previously dry [25]. These climatic phenomena--aggravated as they are by human-caused degradation of nature, such as water and ocean contamination, air pollution, deforestation, over-harvesting of fish, soil erosion, and uncontrolled urbanization--represent a serious threat to the global ecosystem and to population health.
Drought in Mozambique A 1960-1988 study carried out by the National Institute of Meteorology [26] showed that drought is a persistent phenomenon: every year there are periods of drought in some parts of the country, mostly in the southern and central regions. This study enabled researchers to identify the most affected districts of the country, and those that are permanently affected by drought. The last two severe droughts in Mozambique occurred during the 1982/84 El Niño (the largest El Niño of the century, with a temperature anomaly 3-4 degrees C warmer than average) and during the 1991/92 El Niño, the latter initiating the most prolonged El Niño (1991-1995) since record keeping began in 1877. The drought of 1982 to 1984 affected one-third of the country’s population and eight of 11 provinces. The most seriously affected provinces were Inhambane, Gaza, and Maputo, in the southern region of Mozambique [27,28]. The drought in Inhambane persisted into 1984. Since then, the annual rainfall in the southern region of the country has been less than the normal average. The drought of 1991 to 1992, which strongly affected both Mozambique and the entire southern African region, aggravated even more the precarious living conditions of Mozambicans, who also were affected at that time by civil war [28,29]. A peace agreement was signed in October 1992 and democratic elections were held in October 1994. Despite the fact that there was now some political stability, the situation with regard to population health was exacerbated by a drought in 1994-1995, affecting several districts of the southern and central regions of Mozambique [30]. Drought and Its Impact on Health Status in Mozambique Drought has negative consequences on the health status and socioeconomic well being of populations. Drought is strongly related to limited food supplies, whether cultivated or taken from pastoral production, and thus has a direct impact on the nutritional status of populations and on increased population vulnerability to epidemics.
Nutritional
Impacts Famine and food shortage are outcome variables in an equation with multiple inputs, namely political, social, technological, meteorological, and economic. Famines are generally classified as slow-onset disasters that may be precipitated by factors such as prolonged drought, flood, cyclone, or civil strife. In Mozambique, famine has been related to natural disasters, primarily drought. As a consequence of the drought of 1982-1984, 4,000,000 people (one-third of the total population at that time) were directly affected and an estimated 100,000 people died. This drought was described as the worst in 50 years [27,28]. During the drought of 1991-1992 an estimated 1,320,000 people were directly affected, forcing them to seek refuge in urban areas and causing accelerated population growth in the major urban centers of the country. The goverrnment launched an emergency appeal for an additional 300,000 tonnes of food in the form of cereals [26,31]. This drought also killed more than 370,000 cattle in Zimbabwe; crop production was reduced by more than 70%; and 625,000 people required assistance in Namibia. Botswana’s maize crop failed and South African farmers required drought aid: with a previous average of eight millions tonnes of maize produced annually, only two million tonnes were delivered to the grain marketing board [32]. Cassava Related to Thiocyanate Intoxication A spastic paraparesis (Konzo) epidemic occurred in Mozambique in 1981 related to thiocyanate intoxication. A total of 1,102 cases were reported [33]. This epidemic--and the succeeding one--were associated with consumption of insufficiently processed bitter cassava during drought. Serial measurement of urinary thiocyanate concentrations showed a marked seasonal variation, with a peak coincident with the cassava harvest [34]. Since 1981, further “konzo” outbreaks have occurred during war and drought in cassava-staple districts. In 1992, a total of 186 cases were reported and, in 1993, a total of 108 cases. These epidemics occurred frequently in Nampula and Cabo Delgado in the north, at that time experiencing a severe drought. Other provinces of the country namely, Manica and Gaza in the center and south, have reported cases of spastic paraparesis. All these epidemics were associated with bitter cassava consumption and drought [35]. Water-Borne
Diseases Since 1973, when the first cases were diagnosed in Maputo city, Mozambique has been affected by the seventh and current cholera pandemic (2). A cholera outbreak occurred during the drought in 1983-84, at which time seven of the eleven provinces--mostly the central and southern provinces in the most drought-stricken area--were affected. Thereafter, cholera occurred cyclically, but in 1989 the largest (i.e., having the widest geographical spread, the greatest number of cases, and the most severe mortality) and longest epidemic in the country began, ending in June 1994. The highest incidence of cholera in the history of Mozambique was reported in 1992: more than 31,000 severe cases and 750 deaths. This last outbreak was precipitated by the severe drought that occurred in 1991-1992, compounded by precarious and vulnerable conditions under which people live in the major urban centers of the country [36]. At that time, the major urban centers affected by cholera suffered a very significant shortage of water supply. The Pongue river, which supplies water to Beira city in Central Mozambique, was reduced to one percent of the normal flow. Flow was also very low in the Limpopo, Incomati, Maputo, and Umbeluzi rivers, all located in the southern region of the country. People were forced to improvise new sources of water--some shared with animals--and for multiple purposes (consumption, washing, and bathing). Wells were unprotected and well water was untreated and uncontrolled [36]. In June 1992, an outbreak of dysentery (Shigella dysenteriae type 1) hit the country. Zambézia, Tete, Manica, and Sofala were the most affected provinces. In 1993, 80% of the country’s districts were affected and more than 47,000 cases of dysentery were reported. In 1994, about 77,000 cases were reported. Although the epidemic was related to population movements after war and to poor levels of sanitation and poverty [37], the dysentery epidemic was contemporaneous with the cholera epidemic. Drought played an important role in the dissemination of cholera [36] and, while there are no statistical data confirming a causal relationship, the authors believe it probable that drought contributed to the spread of Shigella dysenteriae type 1 in Mozambique (3). Vector-Borne
Diseases The first plague outbreak reported in Mozambique occurred in 1976, in Mutarara district, Tete province, with 15 cases and six deaths. The second outbreak followed in 1977 with 97 cases and 14 deaths. In 1978 12 cases and no deaths were reported [38]. In September 1994, an outbreak of plague was reported in Mutarara district, with 226 cases and three deaths. These outbreaks were related to severe drought in southern Africa associated with ENSO in both periods, 1976 and 1994. Centripetal movement of wild rodents toward domestic rodents looking for sustenance, and centrifugal movement of people hunting for rodents, were considered important to the origin of the outbreak [25,39]. Drought conditions also reduce populations of predators of rodents and alter food sources for these opportunistic species [40]. Rodent infestation can also ravage crops. The Need for Climate Forecasting One may describe three levels of responses to emerging diseases. The first is the need for greater surveillance and response capability; training, and better communication systems, such as the Program for Monitoring Emerging Diseases (PROMED). The second level (midstream) involves the integration of health surveillance with ecological monitoring and improved climate and weather forecasting. The third (upstream) involves addressing the underlying environmental conditions that increase vulnerability, and energy policies that impact the climate system. Integration of health and environmental monitoring and the use of climate forecasting and health early warning systems (HEWS) of climate and weather conditions conducive to outbreaks [41] may become more feasible and can facilitate early, environmentally sound public health interventions (e.g., vaccinations, cleanups, Bti applications, etc.). The El Niño signal can provide early warning of conducive weather conditions for specific regions of the globe. Much of the impact of global environmental change will fall on poorer nations, such as Mozambique, that are more vulnerable to the consequences due to their compromised socioeconomic conditions. Technological progress in understanding the environment and climate dynamics becomes a matter of development, where poorer countries are disadvantaged. This raises ethical and scientific issues, as well as international policy issues. Governments, UN agencies, scientists, and professionals have an opportunity to improve partnerships between the technically advanced nations and the large regions of the globe that are less equipped to deal with climate change and extreme climatic variability [42]. Better understanding of the connections between the environment and disease emergence can promote broader awareness among scientists and policy makers as to the nature of environmental and social vulnerabilities to the spread of emerging infectious diseases and the role of human activities (e.g., land-use change, excessive use of chemicals and antibiotics, and others) in altering the biological controls over opportunistic pests and pathogens. An Urgent Need for Planning The Mozambican government--conscious of drought and other natural disasters and interested in diminishing the impact of these phenomena--established the Department for the Prevention and Combat of Natural Disasters (DPCCN) in 1980 to carry out relief operations in the regions of the country affected by drought. With the beginning and the intensification of the civil war, however, DPCCN was diverted from this mission and was transformed into an agency that could respond only to acute emergency situations. Time and resources were unavailable to develop a real planning process for emergency management as a whole. In addition, the five sites established for seismology surveillance were destroyed during the war and while more than 500 sites had been established for hydrological surveillance, only 16 are now functioning. Thus, the longer term activities aimed at prevention, mitigation, and preparedness for disasters were not consolidated [43]. DPCCN did, however, define some early warning systems in the country: for example, the National Institute of Meteorology provides rainfall surveillance, while the National Institute of Agriculture monitors crop production. The Ministry of Health also defined two early warning systems to cope with natural disasters, namely the Nutrition Surveillance and the Epidemiological Surveillance systems. These systems provide an overall view of health problems related to emergencies and disasters, including drought. Despite these early warning systems, the efforts have not been sufficient to cope with drought in Mozambique. The elaboration of a multi-sectoral plan on preparedness and emergency management in the country is urgent. The key components of this plan should include:
1) Identification of risk areas for drought: This is the first step in preventing serious consequences for the population, for agriculture, and for the environment. The national plan on preparedness and emergency management should define the role that each institution is expected to play and specify channels for data collection, analysis, and distribution. Greater integration of efforts to collect data on health and the global environment is needed. The problem of drought in Mozambique is affected by global and regional issues. First, the ENSO phenomenon, interacting with regional sea surface temperatures and wind patterns, strongly affects weather patterns in the region. Improved regional modelling, taking into account local phenomena, are needed for enhanced predictability. Using numerical models, for example, scientists predicted the 1991-1992 ENSO one year in advance. Current capabilities can provide ENSO forecasting for southern Africa with a lead time of up to one year [44]. Other international initiatives and programs are helping to develop a multinational network of research and application centers to produce and distribute forecast guidance products. Thus, southern African countries should prioritize initiatives addressed to utilize climate forecasting to improve prediction of upcoming anomalous wet or dry periods, for planning in the fields of agriculture, hydroelectric power, water management, and health. Most global circulation models project that El Niño episodes will become more frequent and endure longer with a continued global warming trend. 2) Multinational agreements for managing and sharing rivers and other waterways: Many waterways are shared among the 11 neighboring nations that make up the southern African region. Mozambique should establish agreements with neighboring countries for the control of international rivers that supply water used for agriculture, hydroelectric power, and water consumption for the main urban centers of the region. Further, integrated development projects should be elaborated for the risk areas most affected by drought. Footnotes
1. “Teleconnected” refers to the statistically
significant correlation--beginning in 1877--between ENSO conditions and regional
weather patterns (e.g., drought in northeast Brazil and Southern Africa and excess
rains in southeast Brazil. [Return to text] References
1. Parker DJ, Thompson PM. Floods and Tropical Storms. In:
The challenge of African disasters. UNITAR/WHO 1991:38-59. [Return
to text] SidebarClimate Change and Human HealthThe influence of the environment on health has been considered since the earliest days of medical practice. Hippocrates discussed the distribution and occurrence of diseases influenced by interactions between humans and the earth’s climate. Today there is a worldwide scientific consensus that humans have altered global climate in substantial and, perhaps, detrimental ways. Global environmental change affects health either directly (e.g., heat waves increasing mortality from cardiovascular diseases) or indirectly (e.g., effects on vector- and water-borne diseases [45,46,47]. Climate changes, including alterations in temperature and rainfall, play an important role in the emergence of new diseases and in the reemergence of diseases that had been brought under control through immunization and other public health measures [48,49,50]. Vector-borne diseases (e.g., dengue and yellow fever, malaria, trypanosome, plague, and hantavirus) and water-borne diseases (e.g., cholera) are reemerging and spreading [51,52,53,54,55,56, 57,58]. SidebarThe El Niño Southern OscillationThe Southern Oscillation refers to the difference in sea-level atmospheric pressures between Tahiti and Darwin, Australia. A negative Southern Oscillation Index (SOI) is associated with slackening of easterly winds (westerly-blowing); allowing the western warm pool (WWP) to shift to the east. Thus a negative SOI is associated with an El Niño event in which anomalously warm water reaches the west coast of South America. This usually occurs around Christmas time (thus El Niño has been dubbed “The Christ Child”). El Niño events affect the jet stream and are statistically related to extreme weather events in specific areas of the globe [59]. For example, northeast Brazil usually experiences drought, while southeast Brazil and Peru experience heavy rains and often flooding. Southern Africa has a strong “signal,” and usually experiences drought. The opposite pattern is associated with a cold ENSO event (“La Niña”). Thus a positive SOI and anomalously cold water appear near South America and Southern Africa often experiences heavy rains and flooding during La Niña or cold ENSO events. The event that began in August, 1995, for example, was associated with flooding in Mozambique and South Africa, and there were upsurges in malaria.
*MA is WHO-Associated Professional Officer CDD/ARI in Mozambique. |
