Economic and social impact
More than any other disease, malaria hits the poor. Malaria endemic countries are some of the world's poorest. Rural communities are particularly affected. In rural areas, the rainy season is often a time of intense agricultural activity, when poor families earn most of their annual income. Malaria can make these families even poorer. In children, malaria leads to chronic school absenteeism and there can be impairment of learning ability. Urban malaria is increasing due to unplanned development around large cities, particularly in Africa and South Asia.
Costs to countries include costs for control and lost workdays - estimated to be 1-5% of GPD in Africa. For the individual, costs include the price of treatment and prevention, and lost income.
The estimated costs of malaria, in terms of strains on the health systems and economic activity lost, are enormous. In affected countries, as many as 3 in 10 hospital beds are occupied by victims of malaria. In Africa, where malaria reaches a peak at harvest time and hits young adults especially hard, a single bout of the disease costs an estimated equivalent of 10 working days.
Research indicates that affected families clear only 40 per cent of land for crops compared with healthy families. Knowledge about malaria is markedly low among affected populations. In one recent survey in Ghana, for example, half the respondents did not know that mosquitoes transmit malaria.
The direct and indirect costs of malaria in sub-Saharan Africa exceed $2 billion, according to 1997 estimates.
Biological Impact
Malaria is transmitted by Anopheline mosquitoes, the number and type of which determine the extent of transmission in a given area. Transmission of malaria is affected by climate and geography, and often coincides with the rainy season.
Symptoms of malaria include fever, shivering, and pain in the joints, headache, repeated vomiting, generalized convulsions and coma. Severe anaemia (exacerbated by malaria) is often the attributable cause of death in areas with intense malaria transmission. If not treated, the disease, particularly that caused by P. alciparum, progresses to severe malaria. Severe malaria is associated with death.
Prevention of malaria encompasses a variety of measures that may protect against infection or against the development of disease in infected individuals. Measures that protect against infection are directed against the mosquito vector. These can be personal (individual or household) protection measures e.g., protective clothing, repellents, bednets, or community/population protection measures e.g., use of insecticides or environmental management to control transmission. Measures that protect against disease but not against infection include chemoprophylaxis.
In spite of drug resistance, malaria is a curable disease, not an inevitable burden. Although there is only a limited number of drugs, if these are used properly and targeted to those at greatest risk, malaria disease and deaths can be reduced, as has been shown in many countries.
Disease management through early diagnosis and prompt treatment is fundamental to malaria control. It is a basic right of affected populations and needs to be available wherever malaria occurs. Children and pregnant women, on whom malaria has its greatest impact in most parts of the world, are especially important.
In many countries, most cases of malaria are diagnosed and treated in the home or by private sector practitioners, often incompletely and with irrational regimens. This speeds up the spread of parasite resistance to antimalarial drugs, which poses another problem - a dramatic rise in the cost of treating uncomplicated malaria (which has been seen in some parts of the world).
Whereas formerly malaria control depended on insecticide spraying, now the selective use of protection methods, including vector control, is proving cost-effective and more sustainable. So, whereas house spraying is now restricted to specific high-risk and epidemic-prone areas, increasing use is being made of insecticide-treated bednets.
The disease
AIDS (Acquired Immune Deficiency syndrome) is caused by a virus, HIV (human
Immunodeficiency virus) first isolated in 1983. It has been identified in over 200 countries and territories worldwide and is spreading rapidly in many affected populations, particularly in developing countries.
HIV belongs to an unusual group of viruses called retroviruses, which include viruses causing leukaemia in humans, cats, cattle and other animals, and certain other virus found in monkeys and apes, sheep and goats. Retroviruses also belong to a subgroup called lentiviruses, because they are slow to cause disease.
Economic and social impact
At the end of 1999, an estimated 34.3 million people around the world were living with HIV/AIDS and 95% of these live in the developing world. It is also estimated that during 1999, 5.4 million people (including 620 000 children under 15 years of age) became infected. With 15000 new infections each day, HIV/AIDS is quickly becoming one of the major causes of death and disease worldwide.
While HIV/AIDS is a serious threat to people in all areas of the world, sub-Saharan Africa is most at risk. Of the 5.6 million people infected with HIV in 1999, 4 million live in this region where there were an estimated 2.2 million HIV/AIDS deaths during 1999 (85% of the global total), although only one tenth of the world population lives there. In addition, there are now more women infected than men among the 24.5 million adults and 1 million children estimated to be living with HIV/AIDS in sub-Saharan Africa.
The total spent on HIV prevention in sub-Saharan Africa (excluding South Africa) last year was $165 million from all sources. Current estimates now suggest that sums in the order of $ 2.5 billion are needed for prevention alone. Add the costs of care, and the figure rises dramatically.
Biological Impact
HIV is easily killed outside the human body and therefore can only be transmitted directly from person to person, either by sexual contact, exchange of blood or body fluids or from mother to child. Sexual transmission of the HIV is relatively inefficient and repeated unprotected exposures are normally required. HIV incidence and prevalence can vary greatly from country to country and even within countries, depending on several risk factors and risk behaviors. Since the HIV epidemic is driven mainly by sexual transmission, the level and intensity of risk behaviors (vaginal or anal unprotected sex) in a given community are the main determinants of the spread of the virus. These factors may determine the probability of exposure to HIV infection (e.g.: level and sextent of risk behaviours, high HIV prevalence in the community). Others may influence the probability of HIV transmission per exposure (e.g.: the prevalence of other sexually transmitted infections (STIs), levels of condom use, circumcision). In view of the importance of these determinants, information on risk factors obtained from behavioural surveillance studies and STI incidence and prevalence can help better explain epidemic curves and monitor the impact of interventions. The concept of 2nd generation HIV surveillance, introduced by WHO and UNAIDS, integrates AIDS and HIV surveillance with additional sources of essential data to better monitor the epidemic.
HIV is accelerating the spread of TB! HIV and TB form a lethal combination, each speeding the other's progress. HIV weakens the immune system. Someone who is HIV-positive and infected with TB is many times more likely to become sick with TB than someone infected with TB who is HIV-negative. TB is a leading cause of death among people who are HIV-positive. It accounts for about 15% of AIDS deaths worldwide. In Africa, HIV is the single most important factor determining the increased incidence of TB in the last ten years
The disease
TB, or tuberculosis, is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria can attack any part of your body, but they usually attack the lungs.
Tuberculosis kills 2 million people each year. The global epidemic is growing and becoming more dangerous. The breakdown in health services, the spread of HIV/AIDS and the emergence of multidrug-resistant TB are contributing to the worsening impact of this disease.
Economic and social impact
TB is spread through the air from one person to another. The bacteria are put into the air when a person with TB disease of the lungs or throat coughs or sneezes. People nearby may breathe in these bacteria and become infected.
TB attacks many of the poorest and socially disadvantaged because it is spread by airborne droplets and people who sleep close together in large are particularly at risk. The disease primarily attacks the homeless and people who live in poor, substandard housing, and for this reason was prevalent in the 19th century. Those with low immunity, because of malnutrition or becoming HIV+ are also particularly vulnerable. Social factors such as homelessness, neglect of primary health care and urban decay, contribute to the spread of TB and this need to be address if the pandemic is to be curbed.
With the statistical amount of HIV/AIDS cases this diseases has capabilities of becoming an epidemic the cost at drugs become expensive and as an out come of drug resistance mutation which takes place the random frequency increases.
Biological Impact
The treatment of choice for prevention and for active cases is the antimicrobial drug isoniazid (INH), available since 1956. In infected individuals it is usually used in combination with other antituberculosis drugs such as rifampin, pyrazinamide, and ethambutol. Tuberculosis drugs have to be taken regularly, typically for 6 to 12 months. Many patients abandon their treatment when they feel better; similarly, preventive treatment is often abandoned because of the inconvenience. Such noncompliance is believed to be the main reason for the upsurge in drug-resistant strains of the TB bacilli, many of which are resistant to more than one drug. Drug-resistant TB is difficult to treat and has a much higher death rate.
Preventive measures include strict standards for ventilation, air filtration, and isolation methods in hospitals, medical and dental offices, nursing homes, and prisons. If someone is believed to have been in contact with another person who has TB, preventive antibiotic treatment may have to be given. Infected persons need to be identified as soon as possible so that they can be isolated from others and treated.
An antituberculosis vaccine, bacille Calmette-Guérin, or BCG vaccine was developed in France in 1908. Although there is conflicting evidence as to its efficacy (it appears to be effective in 50% of those vaccinated), it is given to over 80% of the world's children, mostly in countries where TB is common; it is not generally given in the United States. Federal health officials in the United States have stated (1999) that a new vaccine is essential to TB prevention. It is hoped that the determination of the complete DNA (genome) sequence of Mycobacterium tuberculosis, achieved in 1998, will hasten the development of an effective vaccine
People who are infected with TB do not feel sick, do not have any symptoms, and cannot spread TB. But they may develop TB disease at some time in the future. People with TB disease can be treated and cured if they seek medical help. Even better, people who have TB infection but are not yet sick can take medicine so that they will never develop TB disease.
TB bacteria become active if the immune system can't stop them from growing. The active bacteria begin to multiply in the body and cause TB disease. Some people develop TB disease soon after becoming infected, before their immune system can fight the TB bacteria. Other people may get sick later, when their immune system becomes weak for some reason. The combination drug rifater (rifampin, isoniazid, and pyrazinamide) has simplified drug administration. Directly observed treatment, where health-care workers watch patients take each dose of medicine, has proved effective in eliminating the problem of noncompliance in the United States, but monitoring has been less effective in many other parts of the world.
Babies and young children often have weak immune systems. People infected with HIV, the virus that causes AIDS, have very weak immune systems. Other people can have weak immune systems, too, especially people with any of these conditions:
- substance abuse
- diabetes mellitus
- silicosis
- cancer of the head or neck
- leukemia or Hodgkin's disease
- severe kidney disease
- low body weight
- certain medical treatments (such as corticosteroid treatment or organ transplants)
Symptoms of TB depend on where in the body the TB bacteria are growing. TB bacteria usually grow in the lungs. TB in the lungs may cause
- a bad cough that lasts longer than 2 weeks
- pain in the chest
- coughing up blood or sputum (phlegm from deep inside the lungs)
Other symptoms of TB disease are
- weakness or fatigue
- weight loss
- no appetite
- chills
- fever
- sweating at night
Conclusion
Cholera is a disease linked to poverty, and continues -- directly and indirectly -- to impede development. By supporting countries world-wide in their preventive and control measures for cholera, WHO and its partners aim to alleviate the suffering and high burden caused by this intimidating disease.
- Malaria control is everybody's business and everyone should contribute to it, including community members and people working in education, environment, water supply, sanitation, and community development. It must be an integral part of national health development and community action for control must be sustained and supported by intersectoral collaboration at all levels and by monitoring, training and evaluation, and operational and basic research.
- In relation to AIDS at a global level, WHO has established incentives to stimulate research and development into new technologies – particularly vaccines and cost-effective drugs. WHO is working for international regulatory and legal systems, which balance the need to protect intellectual property and the need to ensure more equitable access to essential medicines.
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The incidence of tuberculosis of the lungs, the white plague that formerly affected millions of people, declined from the 1950s until 1984; sanatoriums were closed and routine screening was abandoned in the United States. Then, between 1984 and 1992, the incidence increased by 20%, chiefly because of immigration from a country where it is common and because of AIDS, which leaves people particularly vulnerable to the disease. Renewed efforts at control and advances in treatment have been rewarded with incidence declines each year, amounting to a total decline of 31% from 1992 to 1998.
The roles of antibiotics and vaccines in the treatment of infectious diseases
Vaccination, means of producing immunity against pathogens, such as viruses and bacteria, by the introduction of live, killed, or altered antigens that stimulate the body to produce antibodies against more dangerous forms was introduced in the West in 1796 by Edward Jenner. Jenner demonstrated that rubbing or scraping the cowpox virus (the term vaccine comes from the Latin vacca, cow) into the skin produced only a local lesion but was sufficient to stimulate the production of antibodies that would defend the body against the more virulent smallpox.
Antibiotics are natural chemotherapeutic agents produced by microorganisms and are used to inhibit growth of pathogenic organisms. Most of which are only effective against bacteria.
Vaccination has eradicated smallpox worldwide and prevents such diseases as cholera, rabies, and typhoid fever. Vaccines works with the immune system’s ability to recognize and destroy foreign proteins (antigens) that it determines to be "nonself. Scientists are using this same principle to help the body recognize antigens peculiar to cancer cells. It is also applied in an experimental birth control vaccine that tricks the immune system into believing that human chorionic gonadotropin (HCG), a hormone secreted by a developing fertilized egg, is foreign, thus inactivating it and inducing menstruation even if fertilization has occurred. Vaccines are also used to control animal pests by conferring temporary infertility.
The ability of an organism to resist disease by identifying and destroying foreign substances or organisms is it’s immunity. Although all animals have some immune capabilities, little is known about nonmammalian immunity. Mammals are protected by a variety of preventive mechanisms, some of them nonspecific (e.g., barriers, such as the skin), others highly specific (e.g., the response of antibodies
The widespread and indiscriminate use of antibiotics has led to growth and resistant strains of bacteria, which in turn could cause a health harzard in years for such diseases such as TB.
- http://www.who.int/inf-fs/en/fact094.html
WHO Press Releases, Fact Sheets and Features as well as other information on this subject can be obtained on Internet on the WHO home page http://www.who.ch/
See I. Cohen et al., ed., Auto-Immunity (1986); S. Sell, Immunology, Immunopathology, and Immunity (1987); R. Langman, The Immune System (1989); E. Sercarz, ed., Antigenic Determinants and Immune Regulation (1989); J. Kreier, Infection, Resistence, and Immunity (1990)
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http://www.cdc.gov/health/diseases.htm- control of disease and center.
- Human Health and disease By Richard Fosbery-Cambridge University Press
