Introduction
Viral skin diseases are common in humans, with the majority causing infection in children and immunocompromised individuals. According to Acton (2013), viral skin disease and infections occur in almost every community and region in the world. While some infections are common among people living in certain geographic regions, others are distributed worldwide. Among the most common viral infections in humans are plantar warts and hands, foot and mouth disease. Different viruses cause the two infections, but clinical manifestations in both types of infection are characterized with the appearance of wars and marks on the skin. The purpose of this paper is to examine each of the infections, the nature of the viruses involved and make a comparison based on these areas.
Plantar Warts infection
Overview
A plantar wart is a skin disease caused by infection with human papilloma virus (HPV). According to James et al (2006), the common clinical name of the disease is Verruca plantis, which indicates that the disease occurs on toes of the foot. The aim is to distinguish between plantar warts (infection with HPV on toes) from other HPV infections on other parts of the body, where warts are also a major form of manifestation. According to Shulman and Pod (2005), plantar warts are self-limiting, which means that the infection reaches a point at which it heals without clinical attention. However, the lesions involved are painful and can cause the transmission to other persons. As such, treatment is recommended to decrease the rate of transmission and severity of pain.
Epidemiological studies in the US indicate that about 10% of the population suffers from the disease once or more in life. However, some countries like China and India, though with high populations, have lower incidence rates. For instance, according to, James et al (2006), China and India record less than 1% incident rates of the disease every year. According to a study by Mallory, Baugh and Parker (2001), the most probable cause of these differences can be determined genetically. For instance, genetic studies have shown that whites are more susceptible to warts than Asians and blacks.
Causes of the disease: The HPV virus
Human Papilloma Virus (HPV) belongs to the viral family papillomaviridae that includes a number of DNA viruses that affect animals such as humans, birds, turtles and snakes. The family have a naked or non-enveloped DNA as its genome and each species has a number of sub-species. Differences are noted according to the types of animal infected, the part of the body infects as well as genomic sequences. Majority of the HPV are known to cause no harm in humans. However, warts (verrucae) are the most common manifestation in humans. In addition, recent studies have revealed that HPV infection in the genitals is linked with cervical cancer. In addition, other studies have further shown the existence of a strong link between HPV infection and the development and severity of the cardiovascular disease. Moreover, Gillison (2004) has also shown that oropharynx infection with HPV is linked with the development of oroppharyngeal (throat) cancer.
The virology of HPV has extensively been studied over the last two decades. According to Schiller, Day and Kines (2010), HPV infection affects human basal cells of the stratified epithelium. In fact, it has been shown that this is the only type of tissue that the virus can replicate. It also explains why infection with the virus is limited to certain areas of the body, especially those with high content of these cells. It has been shown that HPV cannot bid to live tissues even those with basal cells of stratified epithelium. To enter the cell, the virus has to use micro-abrasions or mechanical traumatised regions of the body that exposes the basal membrane to infections. According to studies, the virus takes a long time to infect the cells. For instance, it has been shown that the virus may take up to 36 hours to produce the first viral transcripts. Some studies have shown that the process is normally slowed down by the active involvement of antibodies that tend to neutralize infection before the virus overcomes them.
After infection, the infected basal keratinocytes tend to proliferate, probably in response to the viral signals produced by the viral DNA products. studies have shown that viral particles are released from the infected cells after these cells degenerate and burst. This means that the virus does not have a mechanism to lyse the cells. However, the virus has been shown to have a long active life even when exposed. For example, it can last for a number of months at low temperatures. This implies that a planter wart patient can spread the disease months after the initial infection, especially if people tend to walk barefoot.
Molecular studies have shown that HPV DNA is relatively short, with about 8000bps organized within a naked structure. Recent studies have shown that the entry of the virus into the host cells is slow because it depends on the cellular differentiation program. The process of differentiation of the host keratinocyte is the key to studying the HVP infection. The virions of HPV are associated with cellular putative receptors when infecting human keratinocytes. Cellular receptor proteins such as laminins and integrins of subtype alpha are important receptors that aid the virus to infect. The virus enters the basal epithelium through two processes- caveolin-mediated endocytosis and clathrin-medicated endocytosis. Depending on the type of HPV involved, a virion can use either of the process or both. The virus dissociates after attaching to the proteins, releasing the outer region. The viral DNA enters the cellular nucleus, but the process is normally limited by the body immune response. Once in the nucleus, a cascade of transcription process is initiated during the proliferation of the cells. This means that the virus must use the cellular mechanisms to replicate. Each cell contains between 10 and 200 viral genomes. Therefore, the replicating cells will have the virus genome.
HPV Infection: symptoms and complications
Identification of plantar wars includes a simple examination of the toes. Warts appear as small lesions on the human sole. In most cases, the warts take a uniform shape- that of a cauliflower with a cluster of mosaic lesions. The lesions are made up of petechiae that look like black spots under the skin. If scratched, the lesions are painful and may bleed. In most cases, the warts may be confused with corns unless a close observation of the striations on the skin is done.
Hand, foot and mouth disease (HFMD)
Overview
Unlike plantar warts, intestinal viruses such as enteroviruses and coxsackie viruses cause HMFD. According to studies, these viruses belong to family picornaviridae, which has a number of members and strains (Frydenberg & Starr, 2003). HFMD is common in humans, especially affecting children and infants. Infection is through human fluids and products such as stool, mucus, blood and saliva of an infected individual. It is also common during hot seasons, especially in areas where individuals are in constant contact with each other such as in schools. Like HPV, the virus has a long incubation period lasting up to one week.
Virology of HFMD
Like other picornavirus members, coxsackie virus is a naked virus with a positive-sense single stranded RNA as its genome. The virus exists in two groups, A and B, depending on their pathogenesis. Viruses in Group A infect the skin and mucous membranes, resulting into an array of diseases such as hand foot and mouth diseases and conjunctivitis (Frydenberg & Starr, 2003). They are cause flaccid paralysis in humans. In addition, there are more than 20 serotypes of group A viruses.
Group B viruses infect the inner organs in humans as well as laboratory mice. For instance, human heart, liver, pancreas and pleura are normally infected with group B viruses. The infection causes inflammation of the organs infected. Recent studies have shown that insulin-dependent diabetes is linked with pancreatic infection with coxsackie viruses of group B (Hagiwara, Tagaya, & Yoneyama, 2008).
Symptoms and complications
The main form of manifestation in a person infected with HFMD is the appearance of rashes on hands, feet, and mouth. However, a number of other areas develop lesions, ulcers or blisters. For instance, the patient experiences painful ulcers, lesions or blisters in various parts of the body such as on the nose, the face and the body. In addition, an infected person may develop body rash that appears before the sores on hands and soles. In children, the blisters and body rashes are not itchy. However, it has been shown that adults who did not contract the disease while young are prone to infection. In such situations, an adult person experiences extremely itchy rashes (Frydenberg & Starr, 2003). Children may develop rashes and blisters on the buttocks, but this is not a common phenomenon. Apart from these manifestations, the disease has a number of other signs. For instance, children develop diarrhea, sore throat, fever and malaise. In addition, some children may develop fatigue. Loss of appetite and difficulty in eating is a common symptom in infected children.
The disease is likely to be confused with other illnesses during its early onset because it produces common symptoms such as fever and sore throat. However, the appearance of painful sores in the mouth and throat should provide enough evidence to suspect the occurrence of the disease. Most clinical setups dwell on these signs as the primary diagnostic process. In fact, the disease is easy to diagnose. In addition, the disease is self-limiting. Analgesics are commonly used to treat sores on all parts of the body.
Conclusion
A large number of differences exist between HFMD and plantar wart viruses. While HPV is a naked DNA virus with two DNA strands, Picornaviruses that cause HFMD are single stranded RNA viruses. Although the two diseases are caused by different viruses from different groups and different viral characteristics, their manifestation in terms of lesions on the body are a common skin disease in humans. Both diseases are classified as common childhood diseases.
References
Acton, A. (2013). Viral Skin Diseases—Advances in Research and Treatment. Atlanta, GA: Scholarly editions.
Frydenberg, A., & Starr, M. (2003). Hand, foot and mouth disease. Australian family physician, 32(8), 594.
Gillison, M. L. (2004). Human papilloma virus-associated head and neck cancer is a distinct epidemiologic, clinical, and molecular entity. Semin Oncol 31(2), 744–54.
Hagiwara, A., Tagaya, I., & Yoneyama, T. (2008). Epidemic of hand, foot and mouth disease associated with enterovirus 71 infection. Intervirology, 9(1), 60-63.
James, William, et al. (2006). Andrews’ Diseases of the Skin: clinical Dermatology. New York: Saunders Elsevie.
Mallory, S. B., Baugh, L. S., & Parker, R. K. (2001). Warts in blacks versus whites. New York, NY: Cengage.
Schiller, J. T., Day, P. M., & Kines, R. C. (2010). Current understanding of the mechanism of HPV infection. Gynecologic Oncology 118 (1), S12.
Shulman, A. B., & Pod, D. (2005). Survey in China and India of Feet That Have Never Worn Shoes. The Journal of the National Association of Chiropodists, 2(2), 342-349.