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Genes and human disease


Genes and communicable diseases

In addition to diseases which have an inherent genetic component or a genetic influence, there are some major communicable diseases which can be treated with genetic based interventions, HIV/AIDS, tuberculosis, and malaria.give some examples of what you mean by genetic based interventions.

For each of these diseases, genomic interventions are being conducted in all over the world. In the Health Professionals Resources section, one can find examples of best practices in genomics applications to these common diseases.

This section is a brief characterization of infectious diseases that have genetic interventions in the diagnosis/treatment stages. It serves to inform the public about the disease characteristics and to provide links for further resources. However, please note that this is no claim of any genetic component involved in the actual disease process, but rather possible genetic interventions in containing or treating the disease.

Acquired Immune Deficiency Syndrome (AIDS)
Tuberculosis
Malaria


Acquired Immune Deficiency Syndrome (AIDS)

Acquired Immune Deficiency Syndrome (AIDS) is a collection of infections and cancers that people with HIV develop. Human Immuno deficiency virus (HIV) is a retrovirus which takes over the body cells and produces new HIV retrovirus. When someone becomes infected with the HIV virus it begins to attack their immune system. The body’s immune system cells are destroyed, allowing pathogens and cancers which the body might have fought off normally to pose a serious threat to infected individuals due to a significant drop in their resistance levels. This process is not visible and a person who is infected can look and feel perfectly well for many years and they may not know that they are infected. As their immune system weakens they become more vulnerable to illnesses that their immune system would normally have fought off. As time goes by they are likely to become ill more often.

HIV can be transmitted via a variety of means, from unprotected sex (most common method of transmission) to blood transfusions to sharing of needles. Pregnant mothers may also transmit the virus to their unborn child.

HIV symptoms (which often appear many times months after the infection) are similar to flu symptoms, and may disappear after some time. HIV may remain dormant and asymptomatic for years until it surfaces suddenly. A common first symptom of HIV is enlarged lymph nodes for three months or more. This may be accompanied by weight loss, yeast infections, memory loss, skin rashes, etc. According to the Center for Disease Control and prevention (CDC)in the United States, AIDS is the advanced stage of the HIV infection in which a person has less than 200 T4 immune cells per cubic millimetre of blood.

There are two types of HIV viruses, both resulting in forms of AIDS which are indistinguishable from each other. In addition to the two major types, HIV-1 and HIV-2. The genetic composition of these different types distinguishes one from the other.

Prevalence:

There are an estimated 42 million people in the world living with HIV/AIDS, of which 19.2 million are women, and 3.2 million are children below 15 years of age. In 2002, there were 5 million newly infected HIV individuals and 3.1 million deaths relating to AIDS. In the United States, HIV/AIDS is more prevalent in African American and Hispanic communities than Caucasians.

Diagnosis / prognosis:

HIV/AIDS can be diagnosed via a blood test to see the presence of antibodies to the HIV virus. Blood given for donation in many places is screened for HIV before it is administered to patients, as blood transfusion can be one mode of transmission of the HIV virus. HIV/AIDS patients face many serious health conditions. For example, they are more prone to cancers which can be aggressive and devastating. Sometimes, individuals may not be able to carry out their normal lifestyles, while in other cases, individuals may experience bouts of illness and then a calm. There are two general classes of drugs used to treat HIV/AIDS: nucleoside reverse transcriptase inhibitors and protease inhibitors. The first class works during the replication of the virus while the second influences the virus life cycle later on.

Additional resources:


Tuberculosis

TB, or tuberculosis, is a disease caused by bacteria called Mycobacterium tuberculosis that can affect anyone at any age. The bacteria usually attacks the lungs. Particular groups of individuals, however, are shown to be at a higher risk of acquiring the disease than others. These include HIV/AIDS patients, individuals in close contact with TB patients, diabetics, individuals with suppressed immune systems, foreign-born individuals in countries with high TB incidences, healthcare workers, alcoholics, and others. Symptoms of the disease include a persistent cough, fatigue, weight loss, fever, coughing blood, and sweating at night. When an infected individual coughs or sneezes, others nearby are at risk for breathing in the bacteria.

Prevalence:

It is a fact that someone dies of TB every 15 seconds and eight million people develop active TB every year. Each one can infect between 10 and 15 people in one year just by breathing. As mentioned in the WHO Report on Global Tuberculosis Control 2003, the global incidence rate of TB is growing at approximately 0.4%/year, but much faster in sub-Saharan Africa and in countries of the former Soviet Union. Tuberculosis kills more people in India and throughout the South-East Asia Region than any other infectious disease more than HIV, STD, malaria, and tropical diseases combined. In India, more than 1,000 people die from TB every day more than 450,000 per year, 1 every minute

Diagnosis / prognosis:

Tuberculosis is diagnosed with the Mantoux test, in which a small sample of tuberculin is placed under the skin in an arm, and if a bump persists in the area, the individual may have TB. If the person is suspected positive for TB, the doctor may advise a chest x-ray and a mucous analysis as a follow-up. The treatment and prognosis vary for individuals who are TB infected and individuals who are experiencing symptoms of the TB disease. Various drugs therapies are used to treat both individuals. Tuberculosis can be cured if treated well. The best way to prevent TB is to treat and cure people who have it.

Additional resources:


Malaria

Malaria an infective disease caused by parasites that are transmitted through the bite of an infected female Anopheles mosquito. It is caused by four different pathogens Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale , and is present in over 100 countries.

It is transmitted when this female anopheles mosquito bites a infected person and ingests the parasite which grows in its body. When this mosquito bites another healthy person, the parasite is transferred and the person gets infected. These parasites now travels to the person’s liver where they grow and multiply, eventually causing the blood cell to burst open, releasing the parasite throughout the blood stream. Symptoms mock those of the flu and include chills, headaches, muscle aches, and fatigue. Jaundice and anaemia may follow. Individuals may begin experiencing symptoms a little over a week up until a month after infection.

Prevalence:

Malaria occurs in over 100 countries and territories. More than 40% of the people in the world are at risk. Large areas of Central and South America, Hispaniola (Haiti and the Dominican Republic), Africa, the Indian subcontinent, Southeast Asia, the Middle East, and Oceania are considered malaria-risk areas. The World Health Organization estimates that yearly 300-500 million cases of malaria occur and more than 1 million people die of malaria. About 1,200 cases of malaria are diagnosed in the United States each year. Most cases in the United States are in immigrants and travelers returning from malaria-risk areas, mostly from sub-Saharan Africa and the Indian subcontinent.

Diagnosis / prognosis:

The diagnosis for malaria is conducted by analyzing blood for malarial parasites. Prescription drugs can be used to cure individuals of malaria depending on the type of malarial infection, severity of infection, and other factors.

Additional resources:


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