Infectious diseases or communicable diseases are one of the leading causes of death worldwide. These diseases are spread by pathogenic microorganisms, such as bacteria, viruses, parasites, or fungi. Infectious diseases possess greater risk as these diseases can easily transfer from human to human or by other modes. Generally, people with low immunity, infants, and the elderly population are at greater risk of getting an infectious disease.
The mode of transmission can be divided into two parts, namely direct and indirect transmission. Direct transmission occurs through direct contact with sick individuals, animal to person, or from mother to newborn child. In some cases, the transmission may also occur through sexual contact. While in the indirect method, transmission from contaminated water, food, or by Insect bites occur.
As per the WHO, “Infectious diseases kill over 17 million people a year”.
Over the past 20 years, around 30 new infectious diseases have been discovered. Most of these diseases don’t have any cure or treatment. Sometimes the emergence of new infectious diseases such as Ebola infection, Zika infection, and many others have caused severe social and economic crises in the world. For instance, the most recent and ongoing viral infection, COVID-19, has wreaked havoc on the human race. Not only has it resulted in a loss of life, but also the World economy toppling down. The focus of major pharmaceutical companies has shifted in manufacturing a preventive or therapeutic cure against the virus resulting in neglecting other bothersome diseases. Moreover, the studies of the emergence of these diseases, the vectors that spread them, and the vaccine development process take a huge amount of human and financial resources apart from the cost of lives.
Infectious disease causes a wide range of signs and symptoms. The symptoms of different infectious diseases overlap with each other. The symptoms of infectious disease include fever, pains, night sweats, diarrhea, fatigue, weight loss, muscle aches, loss of appetite, coughing, chills, etc.
Some of the leading infectious diseases in terms of a number of cases and deaths worldwide include:
Tuberculosis affects the lungs and can be transmitted from one person to another through droplets from the lungs (via coming in contact with active respiration of the affected person). WHO has considered Tuberculosis as one of the deadliest infectious diseases in 2015. An estimated 10 million people fell ill due to TB while around 1.5 million people lost their lives in 2018. Around 30 countries with high TB burden comprised around 87% of new TB cases in 2018. India is the leading country in terms of the number of cases followed by other Asian countries such as China, Indonesia, the Philippines, Pakistan, and Bangladesh. Apart from these the leading counties with the highest cases outside the Asia continent include Nigeria and South Africa.
The signs and symptoms of TB include coughing with sputum and blood, weight loss, loss of appetite, fever, and weakness or fatigue. People with all age groups are at risk of developing TB, however, adults in their most productive years are at higher risk. With several months of medications, TB is treatable and curable. Being an infectious disease, during the course of treatment, the concerned patient is usually kept away from other people to avoid the spread of disease.
Malaria is a mosquito-borne life-threatening disease caused by a parasite. Worldwide, around 228 million cases of malaria were recorded in 2018, while the number of deaths stood at 405,000. Children below the age of 5 are the most affected group, which comprises around 67% of all the deaths caused by malaria.
The malaria is transmitted through the bite of infected female Anopheles mosquitoes. The other mode of transmission includes blood transfusion, organ transplant, or sharing blood-contaminated needles or syringes, and also from mother to infant before or during delivery.
The symptoms which usually appear 10–15 days after the mosquito bite include fever, tiredness, headache, flu-like illness, muscle aches and chills. Malaria is treatable and curable, however, the delay in the treatment may often lead to death.
The sub-Saharan Africa region accounted for the highest number of cases and death worldwide in 2018. Apart from the sub-Saharan Africa region, some other regions at great risk of malaria are South-East Asia, Eastern Mediterranean, and Western Pacific regions.
Pneumonia is often referred to as acute respiratory infection and is caused by viruses, bacteria, and fungi. Pneumonia affects the lungs of the individual. As per WHO, 15% of children worldwide under the age of 5 lost their lives due to Pneumonia. In 2017, Pneumonia caused 808,694 casualties in children. In the United States, approximately 3,600 people died due to Pneumococcal meningitis and bacteremia in 2017.
Streptococcus pneumoniae (or pneumococcus), Haemophilus influenzae type b (Hib), and respiratory syncytial virus are the major infectious agents of Pneumonia. People of all ages are at risk for Pneumonia, however children with low immunity, below the age of 2, undernourishment and affected with certain illnesses (such as diabetes, immune compromising conditions, chronic heart, lung, kidney, or liver disease) are at higher risk.
Similarly, people with age 65 years or older, regular smokers, and conditions such as chronic heart, HIV/AIDS, cancer, diabetes, or alcoholism are at higher levels of risk as compared to others.
The treatment option for Pneumonia includes certain antibiotics and vaccines. In some severe cases, the patient may require to get hospitalized. As per the CDC, in the United States, pneumococcal pneumonia causes an estimated 150,000 hospitalizations each year. The disease can be easily prevented by addressing the environmental factors, Immunization, maintaining good hygiene, and uptake of nutritious supplements.
Diarrhoea is one of the leading causes of death among children under the age of 5. In Diarrhoea the passage of 3 or more loose or liquid stools per day occurs. In 2017, worldwide, approximately 8% of all deaths among children under age 5 occurred due to Diarrhoeal disease. As per WHO, around 1.7 billion cases of childhood diarrhoeal disease are registered every year, while around 525,000 children under five lost their lives.
The Diarrhoea is caused by a host of bacterial, viral, and parasitic organisms, which are mostly spread by the contaminated water, food, or objects; also form from person to person under unhygienic conditions. Rotavirus is one of the leading causes of acute diarrhea, which can be prevented by vaccination for rotavirus. Similarly, some other measures to prevent diarrhoea includes adequate sanitation, handwashing with soap, safe drinking water, and hygienic food, providing education about virus spread, etc.
The hepatitis consist of 5 strains of hepatitis viruses, identified as types A, B, C, D and E. Hepatitis is an inflammation of the liver and can cause a wide range of health problems. Hepatitis is one of the deadly diseases in the world, it is largely being ignored, but in recent times it got significant attention from the world health bodies. Around 325 million people live with hepatitis infection globally. As per the WHO’s estimates, in 2015, infections with hepatitis B and C virus caused around 1.34 million deaths. The HBV and HCV accounting for about 96% of the hepatitis deaths. In comparison to other diseases such as HIV, TB, and malaria the morbidity and mortality due to Viral Hepatitis are on a continuous rise.
The mode of transmission of Viral Hepatitis varies from type to type. The Hepatitis A virus (HAV) and Hepatitis E virus (HEV) virus are transmitted through consumption of contaminated water or food, areas with poor sanitation and unsafe water can result in the outbreak of these diseases. Hepatitis B virus (HBV) and Hepatitis C virus (HCV) are blood-borne infections, while Hepatitis D virus (HDV) occurs in the person who is infected with HBV, as HDV requires HBV for its replication.
The hepatitis B virus (HBV) is preventable by vaccines. HBV vaccine is helpful in preventing the hepatitis D virus (HDV) and also significantly reduces the transmission risk from mother to child. As of there is no vaccine for hepatitis C. Some of the people infected with Hep C recover on their own, however, in some cases, the life-threatening infection may occur. Research is going on to find an effective vaccine against hepatitis C.
HIV is one of the most deadly diseases in the world. In 2019, around 38 million people in the world were living with HIV & almost 33 million people had lost their lives due to it. HIV attacks and weakens the body’s immune system. The white blood cells called CD4 cells play an important role in fighting infections that are attacked and destroyed by HIV. To check the health of the immune system of the HIV affected people a CD4 count is conducted.
The signs and symptoms of HIV vary according to the stage of the infections and also from people to people. Within the two to four weeks of infection, the affected person experiences flu-like illness. Similarly, other symptoms include fever, rash, chills, night sweats, sore throat, muscle aches, headache, etc. In the later stages, as the virus progresses other symptoms such as swollen lymph nodes, weight loss occurs. In some cases, the affected person may be unaware of the disease until the later stages.
HIV mainly transfer from infected person to another person by having unprotected Sex, sharing syringes and other injection, from mother with HIV to the newborn child, from donated blood and so on.
The current treatment pattern of HIV includes a combination of 3 or more ARV drugs. Antiretroviral HIV Drugs don’t cure HIV but reduce the amount of virus in the infected person’s body. As per WHO, in 2019, around 25.4 million HIV infected people were receiving ART, which covers almost 67% of the HIV infected person. The WHO is making efforts to expand the access for HIV treatment, in order to end the AIDS epidemic by 2030
What are the major challenges in the eradication of infectious diseases?
Over the past few years, it has been observed that the bacteria and other microbes have developed resistance to antibiotics and drugs. The antibiotics are getting less effective over time. Apart from this, many new infectious diseases have been discovered in the past years. As discussed earlier most of these diseases don’t have any cure or effective treatment option. Till the availability of treatment, a huge loss of capital and human life has already occurred.
The socio-economic development of nations around the world is also affected by infectious diseases. The management of diseases requires a major chunk of public healthcare spending in developing countries. The recent outbreak of Covid-19 has almost pushed the global economy in recession.
The inadequate healthcare infrastructure, contaminated water supply, sewage system, geographical and environmental factors, unavailability of medicines and antibiotics, low health knowledge, population growth, poverty are other major issues in the handling of infectious diseases in the developing countries.
By the continuous effort of World health bodies such as WHO and local governments, some of the infectious diseases such as poliomyelitis, leprosy, neonatal tetanus, guinea-worm infection, and Chagas diseases are eradicated or reduced significantly over the past few years. Various research and vaccination programs at the local and international levels are going on to contain the spread of infectious diseases.