Urbanization has played an important role in the
development of underdeveloped and developing countries. It is believed that the
developed countries of the world could achieve fast economic progress due to
large — scale urbanization. Urbanization during the industrial revolution
helped fast development of some European Countries. However the environmental
challenges have been quite difficult to deal with. As already highlighted,
urbanization is a process in which overall development of a particular region
takes place.
New industries are set up and this in turn helps to create large —
scale employment which is much needed in developing countries. Due to
employment, the per capita income of the people rises and the region achieves
prosperity. Urbanization provides better infrastructural facilities, medical
facilities and educational opportunities to millions of people. Urbanization
also helps develop a scientific attitude among people. The overall standard of
living of the people rises considerably because of urbanization. It helps the region to prosper and cater to
the needs of a large population. Urbanization provides plenty of opportunities
for people from all sectors of society to excel and achieve their goals.
Despite these advantages, urbanization is usually attached with numerous
challenges among which includes:
Environmental pollution and Degradation: Pollution and degradation of the environment is one of
the most prominent challenges. The increase number of vehicles on the roads and
industrial wastes are the main source of air pollution.
Urbanization also leads to a rise in the noise
pollution level. Contamination of sea, river and lake water due to various
human activities is also a serious issue resulting out of fast urbanization.
Land pollution is also a matter of great concern. These types of pollution can
cause adverse effects on the health and well — being of people.
River pollution is particularly found to be worse
where rivers pass through cites and the most widespread is contamination from
human excreta, and sewage. In many cites in Nigeria for example, there is
limited access to clean drinking water. The quality of several water sources is
poor, with pollutant levels higher than the WHO’ standard (Alex; 2010). Sadly,
pesticide contamination from urban agriculture, residues from sawmills and
manufacturing industries, waste water from urban drains and municipal dumping
of waste especially human excreta pollute drinking water sources that affect
the health of the urban and peri-urban populations.
Population Explosion: this is a great rise in the population of a particular
area over a time. It has been observed that urbanization and
industrialization lead to an increase in the population of the region at a very
fast pace. The population growth results in a situation where the facilities
provided by the government are to be shared among many people. This can further
cause inequitable distribution of wealth and resources. Providing the huge
population with essential resources becomes a big challenge due to population
explosion. It also puts a tremendous strain on the finances of the country.
Sanitation, water and transport problems:
The rise in the number of vehicle puts a huge strain on
the infrastructure available for transport such as roads and railways. Water
problems are quite common in many parts of urban cities. Keeping the cities
clean and well maintained is surely one of the biggest challenges.
Housing: -
providing shelter to a big population is in deed a big challenge posed by
urbanization. The lack of space for construction of houses and building results
in deforestation which causes several environmental problems. The problem of
slums in urban cities is becoming more and more difficult to tackle due to the
issue of displacement that the huge population residing on these slums will
face.
Rising cost of living and wealth inequality: - The cost of living in urban is quite high compelling
many people to live in poverty. Inequalities in the distribution of wealth
which widens the gap between the rich and the poor is also a serious problem to
deal with.
Increase in crime: - One of the biggest challenges is the increase in the crime rate.
Survey conducted suggest by Charlie that the crime rate is much higher in urban
cites as compared to rural settings. The rise in the number of crime is due to
the need to earn wealth which results in people resorting to unfair means. The
average person in the urban areas suffer the most because of the rise in
criminal activities.
Health challenges: - urbanization is one of the major threats to health in the twenty
first century. For the first time in history more than half of the world
population resides in urban areas. Rapid urbanization is more pronounced in low
to middle income countries of South East Asia and sub-Saharan African (WHO;
2010). About 34% of the total population of the South East Asia Region
is urban. According to UN Habitat (WHO; 2010) over 40% of the urban population
of South Asia live in slums. The urban poor suffer disproportionately from a
wide range of diseases and health problems. Lack of safe drinking Water, poor
sanitation and pollution from nearby transportation, factories and industrial
complexes can harm the health of urban workers and their families. This is
partly because of the degraded quality of basic environmental services such as
clean air, water and soil. Poor urban dwellers often also lack access to health
services and the cost of such services can itself be impoverishing. (WH0; 2OO7).
In Nigeria and other Africa countries, most cities are
characterized by inadequate sanitation, poor waste management and poor state of
public health and infrastructure which have led to the spread of wide variety
of water — borne and other communicable diseases. Speaking to Business Day News
Paper recently at the 2010 physician week organized by the Lagos state branch
of Nigerian Medical Association (NMA) Edamisan Temiye, Lagos State Chairman of
NMA, said that the growing urbanization has become one of the biggest health
challenges of the 21st century to Nigeria and the African continent. According
to Temiye health is a major urban policy issue in Nigeria because poverty and
slum conditions pose a serious public health threat to the country’s rapidly
expanding urban population. In his words “those of us who are living in the
mega city of Lagos are very much aware of the constraints for space and the
rapidly disappearing neigbouring meeting places for relaxation. We are well
aware of the slums often located in the vicinity of comfortable living and well
constructed neighbourhood. Our actions as individuals, community, corporate
organizations and government should be focused towards taking actions to
mitigate challenges of urbanization”.
Nigeria as a nation has over the years been
experiencing an accelerated shift of her population from rural to urban areas.
This rapid rate of urbanization has no doubt engendered several challenges and
problems similar to situations in other parts of the world. Sadly most problems
confronting cities, towns and their inhabitants include inadequate financial
resources, lack of employment opportunities, spreading homelessness and
expansion of squatter settlements, increased poverty, growing insecurity and rising
crime rates, inadequate and deteriorating building stock, services and
infrastructure. Other problems include sub standard and inadequate housing,
slums, transportation problems, low productivity, crime, juvenile delinquency,
lack of health and educational facilities, improper land use, insecure land
tenure system rising traffic congestion, increasing pollution, lack of green
spaces, inadequate water supply and sanitation, uncoordinated urban development
and a,n increasing vulnerability to disaster. For Akin Osibogun, Chief
Medical Director, Lagos University Teaching Hospital (LUTH) Idi-Araba, though
urbanization has its positive effects, one of the health problems urbanization
is confronted with is the issue of mental health as evident in the number of
people with stress, depression and anxiety. He noted that urban cities have the
increased risk factors for non- communicable diseases and their risk factors
such as tobacco use, unhealthy diets, physical inactivity, harmful use of
alcohol as well as risks associated with disease out breaks.
Lastly unplanned urban growth has also exacerbated
communicable diseases including water-borne and food-borne diseases. Diseases
like amoebiasis and tuberculosis thrive in overcrowded conditions and are
exacerbated in dusty environments. Other health threats include diarrhea
diseases, viral hepatitis, typhoid fever, HIV/AIDS, and vector -borne
infectious diseases especially dengue fever.
The dynamic growth of cities can be an economic engine
to lift developing countries out of poverty — but unplanned growth can lead to
detrimental health consequences (WHO; 2010).
SPECIFICITY
OF URBAN POPULATION
The close proximity of people is a prominent urban
factor. Due to large number of inhabitants in cities, there is tendency of
living close to each other. The
world’s densest cities are in Asia and with almost 30,000 inhabitants per KM2
which Murbai in India appears to be the highest.(Emilie et al; 2011).
Population density affects diseases, particularly
those transmitted via respiratory and faecal oral routes like Entamoeba
histolytica and Giardia intestinalis. Because
of high — population density there is an increase amount of shared air space,
which leads to increased exposure to influenza, measles, and Mycobacterium
tuberculosis.
Urban centers usually have higher rates of
tuberculosis infection than rural areas (Tienhardt; 2OO1,). For example
in impoverished sub urban areas of Karachi, Pakistan, the prevalence of
pulmonary tuberculosis is 329 per 100,000 people. much higher than the
prevalence of 171 per 100,000 that was reported by Pakistan National Statistics
(Akhtar et al; 2OO7) Densely populated cities also proved favourable
grounds for the spread of emerging diseases, as shown by the severe acute
respiratory syndrome or the recent, HINI
influenza epidemics. Careful urban planning is crucial to restrict
household overcrowding, and provision of parks and open spaces relieves
congestion.
In most low -income countries, urban expansion is due
to natural population growth. However, migration of people from other urban
centers or from rural areas contributes substantially to the growth of cities
(WHO, 2009). Economic migration and forced displacement can contribute to
population movements. In Amman, Jordan, at least 500,000 of the 2 million
inhabitants have moved to the city seeking refuge from conflict or disaster
area (UN- Habitat; 2010). For urban growth, migration is generally more
important in nations with low rates of natural increase. In China for example, the
floating population of rural migrants moving to coastal cities is about 120
million (Emile et al; 2O11). Large population movements are also
occurring between cities, notably in Latin America and the Caribbean. In Sao
Paulo, Brazil, a third of all urban growth can be attributed to migration from
other cities (Harpham et al; 1995).
Migration therefore, affects the transmission of
communicable diseases in several ways: first, cities might provide favourable
conditions for the spread of germs that are imported by migrants.
Schistosomiasis has established itself in urban areas most probably through
infected migrants (Bella et al; 198O). The snail intermediate host of schistosoma
Spp is present in urban water
bodies, and endemic foci occur in large cities such as in Bamako-Mali, Darel Salam-Tanzania and Kampala-Uganda (Dabo et al; 2003).
bodies, and endemic foci occur in large cities such as in Bamako-Mali, Darel Salam-Tanzania and Kampala-Uganda (Dabo et al; 2003).
Second1y, migrants who are infected may also increase
the transmission of diseases that is already present in a city. In Kinshasa,
Democratic Republic of Congo, the massive inflow of internally displaced
persons from provinces where African trypanosomiasis is endemic contributed to
an increase of ten times in the number of cases report.
Finally rural migrants traveling from non-endemic
areas might also change the epidemiology of infectious diseases already present
in cities. Many new comers do not have the specific immunity for these diseases
and are more susceptible to infections and more likely to develop severe forms
than are residents (Huang et al; 2OO5)
Naive migrants also contribute to the spread of latent forms of the disease. In Kabul Afghanistan, where cutaneous leishmaniasis is endemic, most of the populations become infected and immune in early life. Since 1987, rural — to — urban population movements have substantially increased the risk of transmission among new comers, and the spread of this disease has reached epidemic proportion (Reyburn et al; 2OO3).
Naive migrants also contribute to the spread of latent forms of the disease. In Kabul Afghanistan, where cutaneous leishmaniasis is endemic, most of the populations become infected and immune in early life. Since 1987, rural — to — urban population movements have substantially increased the risk of transmission among new comers, and the spread of this disease has reached epidemic proportion (Reyburn et al; 2OO3).
RURAL-URBAN
MIGRATION
Migration of rural people can add to the urban burden
of parasitic diseases in several ways. Firstly, if rural migrants travel from
non endemic area they will be susceptible to parasite infections that are
endemic in the destination city. For example rural migrants were reported to be
at high risk of acute urban schistosomiasis in Cairo and Belo Horizonte, and of
urban Cutaneous Leishmaniasis in afghan cities such as Kabul (Mott et al;
1990,).
Secondly, urban inhabitants may be at risk from new
infections brought in by the rural immigrants. For vector-borne infections, the
exact impact depends on whether (a), migrants themselves are infected by the
pathogens in question. (b) The city is endemic for the disease (c) migrants
carry the vector(s) or intermediate host(s) of the disease.
As the case may be, a non — infected rural migrant may
bring the infected vector or intermediate host of an infection into a non —
endemic city. This vector can then contaminate the urban environment, leading
to infection among city inhabitants. Out break of chagas disease, filariasis,
and schistosomiasis are all thought to have followed entry of their respective
insect vectors or informed late hosts into metropolitan areas. It is also
possible that new species of parasites could be introduced into urban areas if
suitable vectors for their transmission are already present. New species of
Schistosoma, Leishmania and filarial worms and new zyrnodemes of T. cruzi have
been described in urban areas (Mott et al; 199O). However transmission of these
parasites can only be sustained if the urban environment supports survival and
multiplication of their vectors, facilitating continued spread between humans.
A more complex scenario arises when an infected rural migrant or a rural
migrant bringing an infected vector, moves into a non - endemic urban area. In
either cases, transmission of a disease can be initiated or increased. This has
led to the creation of hyper - endemic foci of Schistosomiasis in cities such
as Darel salaam (Sudan), Harare (Zimbabwe) and Sao Paul (Brazil). It has also
facilitated the transmission of chagas disease in the shanty towns of cities in
Latin America and probably contribut to the appearance of malaria in several
African, Asian and South American cities (Saker et al; 2004).
POPULATION
GROWTH AND ITS INFLUENCE ON
PARASITIC INFECTION:
The population of people living in urban
settings has in recent years increased explosively. In 1950, less than
30 percent of the World’s population lived in urban areas, but according to the
World Bank estimates in 2003, population grew to 48 percent. If trends in
migration and population growth continue, urban areas will witness a remarkable
shift with about 60% of people living in urban settings in the world by 2030.
The United Nations predicts that the world’s urban population will almost
double from 3.3 billion in 2007 to 6.3 billion in 2050 and most of this
increase will be in developing countries where health response systems are
weakest (Emilie et al; 2011).
The urban populations of developing countries are
expected to grow from 1.9 to 3.9 billion people, while the number of urban
dwellers in developed countries will remain almost unchanged (Haumsou et al; 2010). For example in
Africa, a number of mega cities have emerged (with more than ten million
inhabitants) such cities are Lagos and Kano in Nigeria, Cairo in Egypt,
Pretoria and Johannesburg in South Africa. In other mega cities of developing
countries, like Mumbai, Mexico City and Sao Paulo, the populations are now
approaching twenty million inhabitants each (Houmsou et al; 2010).
Urban population increase is a function of both rural
emigration and expansion of existing city population, the relative importance
of which varies by region (Saker et al; 2004).
In Latin America, metropolitan growth has largely
reflected increased migration as a consequence of industrialization and the
search for economic opportunities. In sub-Saharan Africa which
is currently the least urbanized region of the world, the region is undergoing the most rapid transition and urbanization which has resulted in rural impoverishment (Michael; 2000).
is currently the least urbanized region of the world, the region is undergoing the most rapid transition and urbanization which has resulted in rural impoverishment (Michael; 2000).
Several factors lead to increased population in cities
of developing countries. These include. interstate war, internal conflict and
political instability which has’ led to mass migration of people who found
themselves as refuges and lived in ad-hoc interim accommodation in slums or
peri-urban areas. Most of the world’s 6.9 million displaced people and refuges
reside in refuge camps or temporary shelters in developing countries. In these
often crowded environments, where provision of sanitation, clean water, food
and health care services are typically inadequate, also where barriers to
vectors and animals carrying infectious diseases are usually absent or
insufficient, and where person to person contact is amplified, parasitic
infections are common and often devastating. For example, after almost one
million people fled from Rwanda to Zaire (i.e. present Dr. Congo) in
l994,around 500 thousand died within a month due to epidemics of cholera and
dysentery which broke out in refuge Camps (Centre for Disease control; 1995).
Conditions in refugee camps also favoured the out
break of vector borne diseases, skin infections as well as intestinal
helminthiasis. Malaria epidemics are well documented in refugee camps. For
instance, in Afghanistan and Pakistan (Houmsou et al; 2O10) reported that the
course of infection anthroponotic cutaneous leishmaniasis (ACL) in an Afghan
refugee settlement in North Western Pakistan, in which over one — third of the
inhabitants developed active lesions was thought to be, infected migrant
carriers from Kabul.
Because urban populations are characterized by much
higher densities of people, poor housing, inadequate sanitation, unsafe
drinking water, more people sharing small spaces, diseases are therefore much
more easily transmitted
Rapid and unplanned population growth places huge
strains on a city’s infrastructure; often designed to protect the public health
of a small urban elites this infrastructure is difficult to expand to meet the
needs of a much larger population especially those living in shanty towns and
slums at urban peripheries, where parasitic infections are shared among people.
In a metropolitan population of Nigeria, it was
reported that school children whose parents live in slums and urban
peripheries, were more prone to intestinal parasitic infection than their
counterparts that live in residential areas and have affluent parents (Housmsou
et al; 2OO9). These slums and peripheries were characterized by
inadequate supply of clean drinking water, poor environmental hygiene with
refuse dumps every where and tenuous health systems.
According to an estimation, about 50% of the
world urban population lives at the level of “extreme deprivation” and about
70% in some cities (Stephen, 1995) At least one quarter of people living
in urban areas in developing countries do not have access to safe water and 30%
to 50% of solid wastes generated in developing countries urban centers
are left uncollected (WHO/UNICEF; 2000). For example in the Eastern
Korogocho slum area of Nairobi, Kenya more than 100,000 people live around a
dumpsite of 13 hectare where children grow up deprived of basic services such
as water and electricity and play on smelly waste ground, around rotting food,
broken bottles, medical waste and much more. A 2007 UN Environmental programme
(UNEP) report highlighted the prevalence of respiratory and gastrointestinal
problems, skin infections among residents living close to the dumpsite
(IRIN;2OO9).