ABSTRACT
Human health is affected by weather elementssuch as temperature, rainfall, relative humidity, wind direction and others. The aim of this study was to examine the effect of rainfall, temperature and relative humidity on the occurrence of malaria, typhoid and tuberculosis in Onitsha North LGA, Anambra State, this was achieved through the following objectives; determine the pattern of occurrence of rainfall, temperature and relative humidity, determine the pattern of distribution of cases of malaria, typhoid and tuberculosis, determine the pattern of distribution of cases of malaria, typhoid and tuberculosis and to determine the seasonality of malaria, typhoid and tuberculosis (2004-2013).Records of rainfall, temperature and relative humidity was obtained from Anambra State NIMET office, Awkaand the records of malaria, typhoid and tuberculosis cases from the selected hospitals(2004-2013) were also used to carry out this study. Time series analysis was used to analyze the trends of each of the data collected. Pearson Product Moment Correlation analysis was used to analyze the relationship between the occurrenceof the three diseases and the climatic parameters. The seasonal occurrence of the diseases was analyzed by dividing the year into cold dry season, hot dry season and rainy season. The analysisshowed that rainfall, relative humidity and malaria exhibited decreasing trends while temperature, typhoid and tuberculosis exhibited increasing trendswithin the period 2004-2013. The correlation analysis indicated that malaria, typhoid and tuberculosis are influenced differently by the various weather elements. Rainfall showed a significant relationship with malaria with an r value of 0.646 and an insignificant relationship with typhoid and tuberculosis having r values of 0.519 and -0.341 respectively, while temperature showed no significant relationship with any of three diseases with malaria having an r value of – 0.194, typhoid; -0.253 and tuberculosis; -0.102. Relative humidity showed a significant relationship with malaria and typhoidwith r values of 0.852 and 0.807 respectively and an insignificant relationship with tuberculosis with r value of -0.427. The seasonal analysis showed that malaria and typhoid had their highest number of occurrences in the rainy season with 84.87 and 2.46 cases and their lowest in the cold dry season with 76.62 and 1.75 cases relatively, while tuberculosis had its highest number of occurrence in the cold dry season with 16.97 cases and the lowest reported case reported in the rainy season with 11.31 cases. The hypothesis was tested and accepted in the case of tuberculosis and rejected in the case of malaria and typhoid in the study area. It was recommended that all the three tiers of government should come up with enlightenment programs should be conducted to educate people on the effect of climate change on the occurrence of diseases; to also provide safe and adequate drinking water for the masses; and provide free mosquito nets for the residents of the area. The people on the other hand should improve on their sanitation in their environment.
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Human health is affected by natural environmental factors such as temperature, rainfall, relative humidity, wind direction and others. Weather isthe state of the atmosphere at a specific time and place while climate is the long-term manifestations of weather and other atmospheric conditions in a given area. Disease is an abnormal condition of the body or mind that causes discomfort or dysfunction (English 1.2.2 dictionary, 2011).Global warming which is defined by Oxford Dictionary of Science (2005) as an increase over time of the average air temperature of the earth.
Climate affects health in a number of ways;this was reported by Tong (2002) who performed an ecological time series analysis to examine the ecological association between climate variability and the transmission of Ross River Virus (RRV) diseases between 1985 and 1996 in Queensland. The result indicated that although many factors can affect the RRV transmission cycles, RRV is generally sensitive to climate variability and that rainfall, temperature and tidal level appeared to be important meteorological determinants in the transmission cycles of RRV diseases at macro level. According to Thorpe, Frieden, Laserson, Wells and Khtri(2004);in the pre-antibiotic era, tuberculosis mortality rate was higher in the late winter and early spring than any other time of the year, it was suggested that environmental and social factors such as temperature, humidity, sunlight as well as crowding and person-to-person contacts are a source of tuberculosis seasonality particularly in the winter time. Continuous research into the influence of meteorological parameters on infectious diseases is a veritable strategy for proffering sustainable solution to their morbidity; this is because climate affects infectious diseases more than most other disease categories especially in Africa, where the burden of infectious diseases is highest (Wilkinson, 2006). Of the 56 million deaths per annum estimated by WHO as the global burden of diseases, infectious diseases accounted for more than 26percent. Tuberculosis and other respiratory infections are two of the four major contributors to these diseases (WHO 2004a). Going by a recent WHO Global TB Report (2010) approximately 4,700 people die of TB infection daily and a total of 1.7 million deaths in 2009 were due to human infection by the disease.
Researchers like Sawa and Bukhari, (2010); Brunkard, Cifuentes and Rothenberg, (2008); Ayoade (1982) among others have found that there is a close link between local climate and the occurrence or severity of some diseases. Ayoade (1982) stated that weather has the potential to alter the average exposure of condition that is suitable for the vector and disease pathogen. Weather and climate can influence host defenses, vectors, pathogens and habitat, (Epstein, 2002). The temporal and spatial changes in temperature, precipitation and humidity expected to occur under different climatic scenario could affect the biology and ecology of the vectors and intermediate hosts and consequently the risk of disease transmission, WHO (2002). Brunkard, Cifuentes and Rothenberg (2008) stated that climate affects health in a number of ways. These effects may be direct as with heat stress, or indirect as with infectious diseases such as malaria and meningitis (Climate and Health Resources Room, 2008; Griffiths, 1976). The effect may also be either directly on the human body or indirectly through effects on disease-causing organism or their vectors (Checkley, Epstein, Gilman, Figueroa, Cama, Patz and Black, 2000; Chew, Doraisingham, Ling, Kumarasinghe and Lee, 1998; Sung, Murray, Chan, Davies and French, 1987). Temperature and rainfall are climatic causal factors of diseases and a small change in these parameters is likely to have a significant impact on the spread of diseases (Epstein, Diaz, Elias, Grabhern, Graham and Martens, 1998; Bate, 2004). The effects of high temperatures on human health are modified by the amount of moisture in the air. Furthermore, the importance of examining the role of weather on human health cannot be over emphasized. Abrupt changes in weather, such as those associated with the passage of a weather front have been implicated in human discomfort with symptoms such as headache.Changes in weather have been demonstrated to be associated with changes in birth rates, sperm counts, outbreaks of pneumonia, influenza and bronchitis (Kalkstein and Valimont, 2008). Certain levels of humidity are ideally suited to the survival and reproduction of pathogens such as bacteria, viruses, parasites, and their vectors (Nathanson and Martin, 1979). Precipitation leads to increased humidity with consequent effects on humans (Greenwood, 1987) and cold weather adds to chilling of human body, thereby making it more susceptible to disease or aggravating chronic diseases. Scott-Evans (2007), for example noted that some people have symptoms that worsen with cold weather while others suffer more in hot weather. Kalkstein and Valimont (2008) also traced the larger increases of mortality to hot weather extremes which brings about several illnesses. According to Kalkstein and Valimont (2008), low humidity leads to excessive dehydration of nasal passages and the upper respiratory tract during winter and increases the chances of microbial and viral infections. Depending on the amount and timing, it may modify the ecological habitat of parasites, their hosts, and insect vectors such that their growth and survival are affected. Moreover, there is evidence that weather changes may be related to the onset of some diseases, such as common colds and upper respiratory tract infectio Wind in combination with temperature and humidity can affect human thermo-regulation. It can also be a means of spreading the causative agents of disease, insect vectors and allergens (Kalkstein and Valimont, 2003). Winter weather has been linked with increased rates of morbidity and mortality of respiratory diseases including tuberculosis (Nakaji, Parodi, Fontana, Umeda Suzuki and Sakamoto, 2004). The seasonal variability of tuberculosis is quite clearly demonstrated by the epidemiological data; showing mostly a peak in early spring and summer months, (Fares, 2011). Similarly, Abeku (2007) observed that rainfall is considered to be a major factor influencing malaria cases in Africa. Small, Hay and Goetz (2003) found that rainfall rather than temperature was the primary influencing factor in malaria transmission trends in Africa during most of the twentieth century. At least, most of today‟s human malaria population P. falciparum and P. vivax may have had their origin in West Africa and Central Africa respectively (Joy, Feng, Mu, Chotivanich and Kretti, 2003). Nigeria is known for a high prevalence of malaria (Federal Ministry of Health, 2001; Onwujekwe, Chima and Okonkwo, 2000) and it is a leading cause of morbidity and mortality in the country (Federal Ministry of Health, 2001).
As earlier mentioned, climatic variations and extreme weather events have profound impacts on infectious disease. Air temperature dependencies are seen in correlations between disease rates and weather variations over weeks, months, or years (Omonijo and Oguntoke, 2009; Kuhn, Campbell-Lendrum, Armstrong and Davies, 2003; Omonijo, 2008) and in close geographic associations between key climatic/weather variables and the distributions of important vector-borne diseases (Hales, Wet and Maindonald, 2002; Rogers and Randolph, 2000). Impacts of global weather patterns on the environment and living beings are now more visible than ever before, as glaciers shrink, ice breaks up on lakes and rivers at faster rates, trees and animal population shift irregularly, and natural and devastating calamities become a common occurrence.
The rate of reproduction, spread and bites by many pests and disease pathogens depends on weather patterns and are usually high in warmer and wetter conditions. Warming also increases the number of pests and microorganisms due to the creation of optimal circumstances for both metabolism and reproduction at the interface of temperate conditions; this is directly correlated to the transmission and spread of diseases (Robert, 2012).Humans have long recognized that climatic conditions influence the appearance and spread of epidemic diseases (NRC, 2001). Hippocrates observation of seasonal illnesses in the fifth century B.C.E. formed the basis for his treatise on epidemics. Hippocratic medicine which attempted to predict the course and outcome of an illness according to its symptoms also considered winds, waters and seasons as diagnostic factors. Ancient notions about the effects of weather and climate on disease remain in the medical and colloquial lexicon, in terms such as “cold” for rhinovirus infections, “malaria” derived from the Latin word for “bad air” and the common complaint of feeling “under the weather”.
Today, evidence that the earth‟s climate is changing is leading researchers to revisit the long standing relationship between climate and disease from a global perspective (IPCC, 2007b). Increased atmospheric and surface temperatures are already contributing to the world wide burden of disease and premature deaths, and are anticipated to influence the transmission dynamics and geographic distribution of malaria, dengue fever, tick-borne diseases and diarrhea diseases such as cholera (IPCC, 2007a). Global warming is also accelerating the world wide hydrological cycle, increasing the intensity, frequency and duration of droughts; heavy precipitation events and flooding (IPCC, 2007a). These weather events may in turn contribute to and increase the risk for a wide range of vector and non-vector-borne diseases in humans and animals (IPCC, 2007b).
1.2 STATEMENT OF THE RESEARCH PROBLEM
A study carried out by Climate and Health Resources Room (CHRR, 2008) on climate and malaria in Africa showed that where malaria is not adequately controlled, its distribution and seasonality are closely related to seasonal characteristics of the weather, and where there were cases of anomalies such as rainfall anomalies, malaria which is seasonally endemic becomes epidemic in warm semi-arid regions of Africa. Akinbobola and Omotosho (2004) looked at the relationship between meteorological variables and the occurrence of malaria, measles, chicken pox, meningitis and pneumonia in Ikeja, Akure and Kaduna and their results showed that there is a relationship between diseases and the seasons. It showed that malaria and pnuemonia are associated with the rainy season while measles, chicken pox and meningitis are common during hot periods. Adefolalu (1984); Sawa and Bukhari (2010) investigated how temperature relates with respiratory diseases in northern Nigeria and discovered that the diseases thrive more when the temperature is very low.
Ilemona (1983) studied the occurrence of pneumonia among children below the age of 5 years in Zaria and reported that the occurrence of pneumonia widely depends on the variability of weather, indicating that colder months recorded more cases of the disease. Ogbaji (2006) studied the role of temperature in the distribution of malaria in Zaria. The researchers result showed that there is a positive relationship between temperature extremes and the prevalence of malaria. December to February recorded less cases of malaria while March to May recorded more cases. Kaplan (2009) researched into the effects of the weather patterns on head ache and it was clear that patients were sensitive to a combination of temperature and humidity changes, demonstrating that there is a relationship between weather and migraine. Malek (1999) showed that high humidity can aggravate arthritis and a warm wind might bring on migraine and emphasized that the effect of temperature on human health is more when compared to humidity and air pressure. Oshaji (2000) studied the effect of weather in the distribution of some common diseases in Zaria and discovered that there is a relationship between temperature extremes and cerebro-spinal meningitis. Bukhari (2009) studied temperature and rainfall variability and the outbreak of cerebro-spinal meningitis and measles in Zaria Local Government Area and observed that there is a strong positive relationship between temperature and outbreak of cerebro-spinal meningitis. Measles showed a negative relationship with rainfall while meningitis had no significant relationship with rainfall. Bako (2012) investigated the influence of weather elements on the occurrence of some common diseases in Kafanchan, Kaduna state using correlation and regression analysis. The researcher observed that malaria showed a significant relationship with both rainfall and relative humidity and also that there is a significant relationship between typhoid fever and relative humidity and rainfall and that the occurrence of typhoid is higher when relative humidity is higher during the rainy season. The researcher concluded that although various diseases are influenced by different weather elements, humidity has a high impact on malaria, pneumonia and diarrhea, temperature on measles and meningitis, rainfall on typhoid and cholera. Ayanlade, Adeboye and Babatimehin (2013) found out that
malaria transmission based on climatic parameters occurred between April and October in their zone B classification of Nigeria of which Anambra State was part of. Using Principal Component Analysis (PCA), Non-hierarchical Clustering and GIS raster techniques, they concluded that seasonality of climate influences the variation in malaria transmission in Anambra State and Nigeria as a whole.
Most of the cited studies were carried out in the northern part of Nigeria and they focused mainly on the effect of some weather elements on the occurrence of malaria, pneumonia, meningitis and migraine.Only few studies e.g. Ayanlade, Adeboye and Babatimehin (2013) focused on the south eastern part of the country (Anambra State as a whole), and they only looked at malaria. To the best of the researcher‟s knowledge, there is no study that has correlated weather elements of temperature, rainfall and relative humidity with Malaria, Typhoid and Tuberculosis especially in this study area. It is this gap in knowledge that this study intends to fill. Thus, this study attempted to answer the following questions:
- What is the pattern of occurrence of temperature, rainfall and relative humidity in the study area?
- What is the pattern of occurrence of cases of malaria, typhoid and tuberculosis in the study area?
- What is the effect of temperature, rainfall and relative humidity on the occurrence of these diseases?
- Is there seasonality in the occurrence of malaria, typhoid and tuberculosis in the study area?
1.3 AIM AND OBJECTIVES
The aim of this study was to examine the effectof rainfall, temperature and relative humidity on the occurrence of Malaria, Typhoid and Tuberculosis in Onitsha North Local Government area of Anambra State from 2004 to 2013.
This research aim was achieved through the following objectives which are to:
- determine the pattern of occurrence of rainfall, temperature and relative humidity between 2004-2013 in the study area.
- determine the pattern of distribution of cases of malaria, typhoid and tuberculosis in the study area for the same period.
- determine the pattern of distribution of cases of malaria, typhoid and tuberculosis in the study area.
- determine the seasonality of malaria, typhoid and tuberculosis in the study area.
1.4 RESEARCH HYPOTHESIS
The hypothesis for this study is that there is no significant relationship between weather elements (rainfall, temperature and relative humidity) and the occurrence of malaria, typhoid and tuberculosis in the study area.
1.5 SCOPE OF THE STUDY
This study examined the effects of rainfall, temperature and relative humidity on the occurrence of malaria, typhoid and tuberculosis in Onitsha North Local Government Area of Anambra State from 2004 to 2013. It is concentrated more in the inland Onitsha North local government area because this is the area where a large proportion of the population is concentrated and also where most of the hospitals are situated. This study focused on some selected hospitals in the study area which have records of up to 10 years (2004 to 2013) of the common diseases in the study area because most of the hospitals do not have complete hospital records of up to 10 years
1.6 JUSTIFICATION OF THE STUDY
Weather has profound effect on human health and well-being. The importance of determining the role of weather in human health cannot be understated. Although there has been remarkable progress in medical science, reports of large increases in mortality during heat and cold waves are usually more common in developing countries because they have the lowest coping capabilities due to underdevelopment and poverty. It is good to know the climatic conditions that favour the persistence of the vectors that transmit most of the diseases in order to know the best time to carry out mitigation measures. This study would show the role if any weather elements play in the prevalence of some diseases. This study also serves as a source of enlightenment/additional information to fellow researchers, health workers, policy makers and the general public on the season in which certain diseases are more prevalent so as to check the spread of these diseases as well as reduce mortality rate in Onitsha North local government area of Anambra state.
