What do you know about Hepatitis A Infection?

 

 

                                                          Abstract

Hepatitis A Infection is caused by or hepatitis A virus (HAV). It is one of the most frequently occurring food-borne or water-borne diseases. Even though it is usually non-fatal it might lead to acute liver failure leading to high mortality. Infection by this virus during the early child hood is usually asymptomatic and leads to the development of life long immunity to this virus. The rate of this infection depends largely on the socioeconomic conditions of a place. The rate is very low in developed countries with good sanitary and hygienic conditions and more in developing countries with very poor sanitary conditions. However, people living in developing countries with transitional economies are considered to be at a higher risk of developing this infection Thus, conducting large-scale immunization programs against HAV is essential in these regions. This virus gets transmitted through the oral fecal route and can be prevented by adopting personal hygiene practices.

 

Introduction

Hepatitis is characterized by the inflammation of the liver and is caused by various factors like, attack of viruses, overconsumption of alcohol, as a side effect of certain medicines and trauma. Out of the four major types of viruses causing hepatitis, HAV or hepatitis A virus, causes acute, usually self-limiting infection of the liver. The attack by this virus is followed by the sudden and sharp rise of symptoms which persist for a short duration (less than two months) with no long-term impacts. Even though this infection is not fatal, it can cause debilitating symptoms and acute liver failure leading to high mortality. Hepatitis A infection is one of the most frequently occurring food-borne or water-borne diseases and occurs both sporadically and epidemically across the world. For example, an epidemic of hepatitis A was reported in Shanghai in 1988 which affected about 300,000 people. Approximately 1.4 million clinical cases of hepatitis A are reported across the world every year (Hepatitis A, 2013). This infection causes jaundice-like or flu-like symptoms. People suffering from this infection often need hospitalization and cannot continue with their normal work until a month. This leads to substantial medical and economic burden. The frequency of death due to this infection is approximately 3-6 deaths per 1000 reported cases (Centers for Disease Control and Prevention, 2011). The aim of this research paper is to provide information about the epidemiology, mode of transmission, symptoms, diagnosis and management of the disease. This paper also provides information about the efficiency of vaccines in prevention of the disease.

 

Epidemiology of Hepatitis A Infection

The rate of hepatitis infection depends on the socioeconomic development of a particular area. This disease usually does not lead to any symptoms in children and induces lifelong immunity in them, if affected by this disease during childhood. In the areas of low endemicity, for example, developed countries with good sanitary and hygienic conditions, the occurrence of this infection is noticed only in high risk group persons or as outbreaks involving a small number of people. This infection shows intermediate levels of endemicity in developing countries with transitional economies, where the sanitary conditions vary. Even though people living in these areas escape the infection during their early child hood due to the improvised sanitary conditions, they succumb to this disease during their older ages because they haven’t acquired adequate immunity. This leads to large outbreaks of HAV infections in these areas. High endemicity of HAV infection is noticed in developing countries with very poor sanitary conditions. Most of the children in these areas are affected with HAV infection with no upsurge of symptoms and acquire life long immunity, hence making clinical cases of hepatitis A uncommon (Hepatitis A vaccine, 2003).

HAV virus is a non-enveloped virus which belongs to the Picornaviridae family. Currently, four vaccines are internationally available, which are safe and effective in providing long lasting protection from this microbial disease (Centers for Disease Control and Prevention, 2011).

 

Mode of Transmission

HAV infection gets transmitted through the oral fecal route when a healthy person consumes food or drinks contaminated by the feces or stool of HAV infected person. This usually happens when an infected person does not adopt healthy hygienic habits such as washing hands after using the toilet, washing hands and food ingredients before preparation of food etc. Travelers are usually infected when they consume infected water or chilled beverages. Having sex with an infected partner or illegal drug use can also spread the disease. Casual contacts, as observed in schools or office, do not spread the disease (Hepatitis A: Questions and Answers, Information about the disease and vaccines, 2012).

 

Symptoms of Hepatitis A Infection

The prodromal phase or the onset of the disease is marked by flu-like symptoms including: gastrointestinal problems like nausea, vomiting, anorexia and abdominal discomfort, occasional headache, constipation, diarrhea, itchiness, cough and pharyngitis. There are no specific symptoms for the identification of this disease during the initial stages. It generally takes 15-50 days for the symptoms to appear after a person comes in close contact with an infected person.  This phase is followed by jaundice, which is marked by yellowing of the skin and eyes, dark urine and pale stools. Symptoms like fatigue, nausea, and vomiting increase with the progression of jaundice. Abnormal enlargement of the liver, spleen and lymph nodes is often observed during examination. These symptoms usually last for two months but, in rare cases can also continue till 6 months. Symptoms observed during the convalescent stage include physical discomfort, hepatic tenderness, and irregularities in liver functioning (Hepatitis A -Summary, 2010) (Hepatitis A: Questions and Answers, Information about the disease and vaccines, 2012).

 

Diagnosis of Hepatitis A Infection

The diagnosis of this disease is based upon symptoms observed and laboratory tests. A blood test is carried to test the presence of IgM antibodies to hepatitis A virus (anti- HAV antibodies). This test is known as “IgM class antibody to hepatitis A virus”. Blood tests also help to detect if the person was infected with this virus in the past. This test is known as “total hepatitis A antibody test”. Hence, infection by this virus in the past or a mere suspicion due to exposure to the virus can also be ruled out by this test. Elevated levels of Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum, due to jaundice can also be detected through liver function tests. The levels are usually higher than 1000 IU/L. An elevated level of Bilirubin (up to 500 micromoles/L) also indicates the presence of infection (Hepatitis A: Questions and Answers, Information about the disease and vaccines, 2012) (Hepatitis A –Investigations, 2010).

 

Treatment of Hepatitis A Infection

HAV infection cannot be directly cured as there are no medicines available which can treat this disease. An infected person is managed with only supportive care, which includes bed rest, pain relief medications like ibuprofen and treatment of nausea and itch. Therapy also focuses on rehydration and nutritional support as water and nutrients lost through vomiting and diarrhea should be replaced. The liver function and prothrombin time (time taken by plasma to clot) needs to be monitored from time to time. The patient needs to be hospitalized when symptoms become very severe (Hepatitis A: Questions and Answers, Information about the disease and vaccines, 2012) (Hepatitis A -Summary, 2010).

 

Why is prevention of hepatitis A infection through vaccines essential?

                        Even though hepatitis A is usually self-limiting and case-fatality rate is generally low, the suffering of the patient as a result of the infection is a point of concern. Moreover, an individual is put to a huge economic burden as, direct and indirect medical costs including the infection control measures are high. This infection imposes huge economic burden on the society, especially in countries showing low or intermediate endemicity. The chances of infection being spread to healthy individuals from an infected person are more during the first two weeks before the infected person develops symptoms like yellowing of skin and eyes. This makes it difficult to arrest the transmission of the infection from the infected person, as the person does not even realize that he/she has been infected. None of the currently available drugs have the potency to cure HAV infection and an effective antiviral medication which can arrest this virus has not yet come up as a realistic option. Socioeconomic development can control the transmission of this disease to some extent, as it is associated with improved sanitation and health education. But socioeconomic development is relatively low in some parts of the world (Hepatitis A vaccine, 2003) (Hepatitis A: Questions and Answers, Information about the disease and vaccines, 2012).

 

The above discussed factors make the prevention of hepatitis A infection through immunization very essential. The protective role of anti-HAV antibodies developed in response to infection which persist for life has been well studied. These antibodies protect an individual from the re-occurrence of the disease for the rest of the life. Hence, immunization through vaccines along with improved sanitation and food safety are highly efficient in combating HAV infection. Both pre- and post-exposure prophylaxis of the disease is possible with the help of immunoglobulins. For example, a person can be immunized shortly before entering a disease-endemic area or after being exposed to hepatitis A virus (Hepatitis A vaccine, 2003).

 

WHO’s Recommendations on Hepatitis A Vaccine

According to WHO, all the currently available vaccines against hepatitis A are absolutely safe as they contain an inactivated virus and none of the parts of the vaccine is live. However, these vaccines cannot be administered to children below one year of age. This vaccine can be safely injected to children between their first and second birthdays. Children and adolescents living in highly endemic areas should be essentially vaccinated. Apart from this, people who are frequent travelers, men who have sex with men, people who use injectable or non-injectable illicit drugs, people suffering from chronic liver diseases, people suffering from blood clotting disorders, persons treated with clotting factor concentrates and persons handling hepatitis A virus in research laboratories should get immunized with hepatitis A vaccine. Under special situations like outbreaks of hepatitis A infection or exposure to the virus, unvaccinated children and adolescents are recommended to get hepatitis A vaccine. WHO recommends two doses of hepatitis A vaccine with a 6 months gap between the two doses of vaccine. People who show severe life-threatening allergic reaction to hepatitis A vaccine should avoid the second dose of vaccine. Pregnant women should take the opinion of the doctor before getting vaccinated. The risks associated with this vaccine are very mild like soreness, loss of appetite, headaches and tiredness (Centers for Disease Control and Prevention, 2011). These problems persist for 1 or 2 days, hence making this vaccine much safer.

 

Criteria behind Large-Scale Immunization Programmes against HAV

Large-scale immunization programs against HAV should be carefully planned based upon factors like endemicity of the diseases in the targeted area and number of people susceptible to this infection. In highly endemic areas, almost everyone gets infected during the early childhood without showing any symptoms. As a result, they acquire natural immunity against this infection hence preventing clinical hepatitis A during adolescence and adulthood. In these areas, large-scale immunization programs or inclusion of the vaccine in routine childhood immunizations is not recommended. The risk of hepatitis A infection in adults is relatively high in the areas of intermediate disease endemicity, making it a significant public health burden. Large-scale childhood vaccination is considered to be the apt method of prevention along with health education and improved sanitation in these areas. Hence, countries like U.S., Israel, China, etc have introduced this vaccine in routine childhood immunizations.

 

Conclusion

Hepatitis A is a preventable disease and in case of out breaks, the transmission of the virus can be arrested by taking care of few factors like, supply of safe drinking water, providing education about personal hygiene practices and proper disposal of sewage within communities.

 

References

 

Centers for Disease Control And Prevention. (2011) Hepatitis A Vaccine, What You Need to Know. Vaccine Information Statement. U.S. Department of health and human services.

Hepatitis A. (2013). Who.int. Retrieved Aug 26, 2013, from

http://www.who.int/mediacentre/factsheets/fs328/en/

Hepatitis A vaccine. (2003). Who.int. Retrieved Aug 26, 2013, from

http://www.who.int/vaccines/en/hepatitisa.shtml

Hepatitis A: Questions and Answers, Information about the disease and vaccines. (2012). Retrieved Aug 26, 2013, from. www.immunize.org

Hepatitis A - Summary. (2010). Nice.org.uk. Retrieved Aug 26, 2013, from

http://cks.nice.org.uk/hepatitis-a#!topicsummary

Hepatitis A - Investigations. (2010). Nice.org.uk. Retrieved Aug 26, 2013, from

http://cks.nice.org.uk/hepatitis-a#!diagnosissub:2

 

Impact of Nanotechnology on Medicine

The curiosity of the human brain knows no limits, and fabrication of materials at the nanometer scale (One meter = 1 billion nanometers) is an outcome of such supreme power of the human brain. Ever since the concept of nanotechnology has been introduced by Richard P Faynman in 1959, various nanoparticles of dimensions ranging from 1 nm to 100 nm have been designed and used in multiple areas related to human life. Nanotechnology involves the use of nanoparticles made by the perfect arrangement of molecules in such a way that these dwarf particles gain all the desired chemical and physical properties. High precision and functional perfection of these devices make them very helpful to mankind (Khan, 2007) (Patil et al., 2008). Applications of nanotechnology in the form of cheaper solar energy collectors, environmentally-friendly batteries and supercapacitors that store energy help us to protect our precious environment. Nanobiotechnology refers to the use of nanotechnology in the field of health and medicine to promote earlier detection and better diagnosis of diseases. The application of nanomedicine has made it possible to carry out a highly targeted delivery of drugs making the concept of personalized medicines a dream come true (Wojnicz, 2011).

Disadvantages of Conventional Medicines

The major limitations of the current medicines are their non-specific action and decreased efficacy. Anticancer chemotherapeutic drugs are a good example of non-specific action of drugs as they damage the adjacent healthy cells along with the cancerous cells, leading to adverse effects like bone marrow suppression, cardiomyopathy, hair loss, etc. This decreases the efficiency of these drugs. Sophisticated techniques to detect the presence of disease at an early stage are not available for all known diseases. These diagnostic techniques are very lengthy in some incidents, as they involve the extraction of a sample and its analysis at a different location. Some conventional surgical procedures are intensive and demand a long stay of the patient in the hospital affecting the patient’s life in multiple ways (Surendiran et al., 2009).

Advantages of Nanobiotechnology

Nanoscale-structured materials promise to revolutionize multiple sub-disciplines of medicine. Nanoparticles made up of tiny fluorescent 'quantum dots” make the early detection of diseases feasible. As these quantum dots fluoresce brightly, the precise area of the diseases can be pinpointed at a very early stage with the help of sophisticated imaging techniques. Devices like 'lab-on-a-chip' are nanotechnological devices that make the instantaneous diagnosis of certain diseases feasible. Nanorobots can facilitate the targeted delivery of the drug precisely at the cellular or molecular level, hence increasing the efficacy of the drugs (5).

Applications of Nanotechnology

Some of the current applications of nanotechnology in the field of medicine include:

Targeted drug delivery system. Nanorobots can target the drugs to a precise area of the human body and reduce the chances of side-effects. The amount of drug and the time of the drug release can also be controlled with the help of an electric pulse. These robots can also monitor the sugar levels in blood (Khan, 2007). Liposomes are spherical nanoparticles made up of bi-layer membranes. They can be used in the delivery of liposomal drugs. Nanoshells, which absorb the infrared radiations of the electromagnetic spectrum, prevent the destruction of the healthy tissues during cancer treatment. Fullerenes, also known as “bucky balls”, act as free radical scavengers as they contain a large number of conjugated double bonds at the core. They help in the transport of anticancer agents and antibiotics, and protect the mitochondria from injury. Nanopore devices can act as semi-permeable membranes. They can be designed to allow the entry of oxygen and glucose to protect the transplanted tissues from unwanted host immune responses. At the same time, immunoglobulin and cells are blocked by this device.

Regenerative medicine. Manipulation of the cell proliferation and differentiation has become possible due to nanotechnology. Nanoparticles similar to the human tissues can be designed. For example, bone-like nanoparticles can be introduced to supplement the degraded bone tissues (Khan, 2007). Experiments are being carried out to replace the damaged nerve cells also.

Prevention of disease. Unwanted fat deposits in the arteries and veins are the cause of heart attacks. Specialized nanorobots capable of removing these unwanted fats can help in the prevention of heart diseases. Iron nanoparticles, which specifically attach to the tumors, help in the treatment of cancer. When magnetic field is applied these particles, they get heated up due to which the tumor cells get cooked and die (Khan, 2007).

Use of nanorobotics during surgery. A programmed surgical robot can replace the necessity of the conventional invasive techniques of traditional macro-surgery. They can guide the surgeon in detecting the site of pathology. These nanorobots can also correct lesions by manipulating them in a minimally invasive manner. A supervising surgeon is guided by ultrasound signals and an onboard computer during these manipulations (Patil et al., 2008) (6).

Use of microbivores against pathogens. Microbivores are artificially designed phagocytes that have the potency to circulate in the blood stream and engulf various foreign pathogens like bacteria, viruses, or fungi. They function like white blood cells (WBCs) and possess a greater efficiency than WBCs. These devices can clear septic infections in less than an hour (Patil et al., 2008) (Surendiran et al., 2009).

Application of nanotechnology in gene therapy. Gene therapy uses viral vectors to deliver desirable DNA to the host. These viral vectors are often considered non-self and a host immune response is triggered against them, due to which they get rejected. Under such conditions, the delivery of genetic material with the help of nanoparticles can act as an effective gene delivery system. Liposomes target the liver cells and can be used to cure various liver disorders (Surendiran et al., 2009).

Limitations of Nanotechnology

            Even though nanoparticles have immense potential to revolutionize the field of medicine, their application is very limited as they pose a serious threat to the environment when produced in large quantities. Upon disposal into water bodies, these nanoparticles can kill the bacteria impacting the base of the ecosystem. They also affect the ozone layer. As these particles are very small in dimension, they can also affect the health of the lungs. Further research is required in this line so that healthy, environmental friendly nanoparticles are created which can prove to be efficient solutions to many diseases.

 

References

 

Coombs, R. (1996). Nanotechnology in Medicine. Informa Healthcare.

Khan, A (2007). NANOTECHNOLOGY: Applications in medicine and possible Side-Effects. Faculty.kfupm.edu.sa. Retrieved January 28, 2014, from http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCcQFjAA&url=http%3A%2F%2Ffaculty.kfupm.edu.sa%2FMATH%2Fsdkhan%2FARCHIVE%2Fnanotech-214.pdf&ei=F3HnUoPOCsTRrQemuoHwDA&usg=AFQjCNExFSnNyk3SzUH1TwK2vtInbN0aUQ&sig2=WeiztTQ-UU5e3hmFu1Jj-w&bvm=bv.59930103,d.bmk

Nanotechnology for Medical Applications and Environment. (2014). Nano.org.uk. Retrieved January 28, 2014, from http://www.nano.org.uk/nano/what-is-nanotechnology-2

Patil, M., Mehta, S, Dhoom., Guvva, Sowjanya. (2008). Future impact of nanotechnology on medicine and dentistry. Indian Soc Periodontol, 12(2), 34–40.

Surendiran, A., Sandhiya, S., Pradhan, C, S., and Adithan, C. (2009). Novel applications of nanotechnology in medicine. Indian J Med Res, 130, 689-701.

Wojnicz, R. (2011). Nanomedicine as the basis of personalised medicine. Kardiol Pol, 69(10), 1107-8.