Coccidioidomycosis as a Fungal Infection - Research Paper Example

? Coccidioidomycosis Coccidioidomycosis Introduction Coccidioidomycosis is a fungal infection, which occurs in humans and other animals as a result of inhaling fungal spores of the Coccidioides species. The two main species that cause Coccidioidomycosis are Coccidioidesimmitis and Coccidioidesposadasii. The etiological agents are almost always found in the environment and can infect numerous species of mammals and a few reptiles. Epidemiological studies show that the etiological agent occurs in soils found in regions of the southwestern United States, Mexico, and some regions of Central and South America. In areas regarded as Coccidioidomycosis “hot spots”, statistics indicate that over 70% of the populations in those areas have suffered from the infection. Coccidioidomycosis is relatively mild or even asymptomatic, but it can turn to be severe when it affects the elderly or immunocompromised. Etiology Coccidioidomycosis is caused by dimorphic, soil-borne, ascomycete fungi Coccidioidesimmitis and C.posadasii, which are soil-borne microorganisms. The two species differ in characteristics such as tolerance to heat and salt, but there is no any significant difference in their pathogenicity. The two species are soil saprophytes that propagate in semiarid regions that have sandy, alkaline soils. In the mold stage, Coccidioides species can survive under extreme environmental conditions such as alkaline, temperatures and high salinity conditions. However, these organisms fail to thrive well in the presence of other soil fungi and bacteria in conditions that do not make up their usual niche (Clemons, 2007). Growth of Coccidioides species is facilitated by two asexual reproductive structures, which are the arthrospore and endospores. The molds growing in the environment produce the arthrospore that are later dispersed by wind. In favorable environmental conditions, arthrospore germinate into new mycelia. In some occasions, arthrospore are infectious to both humans and animals, but in such situations animals are the accidental hosts. Nearly all incidences of Coccidioidomycosis infections occur through inhalation of the fungal spores. Disturbance of contaminated soils by humans and animals increases the aerosolization of arthrospore. Epidemics are highly likely to occur when periods of heavy rains, which promote the growth of mycelia, are succeeded by seasons of drought and winds. Fully developed arthrospore are extremely resistant to harsh environmental conditions and remain viable in the environment for years in the soil and dust (Clemons, 2007). The arthroconidia infects the lungs to become spherules. The spherules increase in size creating a room for endospores to develop. After the spherules attain maturity, they rapture to release the endospores which form new spherules. In some cases, endospores can spread to other body parts through blood and lymph fluid causing systemic infection (Acton, 2011). In extremely rare occasions, Coccidiodomycosis can be spread directly between persons or from animals to human beings. Studies have shown that infections spread from one person to another are systemic in nature, which increases the chances of spreading. In other occasions, Coccidioides species can be transmitted through organ transplant (Clemons, 2007). Epidemiology Coccidioides species are endemic in certain regions of the Western Hemisphere. Nearly all the areas that are endemic lie between latitudes 400 North and 400 South (Friis & Sellers, 2009). The endemic areas have semiarid climates marked with hot summers and alkaline soils suitable for propagation of Coccidioides spores. Studies have found out that Coccidiodomycosis infections are not only affecting people living in the endemic regions, but have found their way to other non-endemic regions. This phenomenon is attributed to the increased travel of populations of people to the endemic regions. Persons from non-endemic regions get Coccidioidomycosis infections, but it becomes difficult to diagnose the condition in those areas since medical experts fail to consider it in the differential diagnosis (Friis & Sellers, 2009). In the United States, the highest numbers of infections occur within key endemicity regions found in southern Arizona, California, Southern New Mexico, and West Texas. Current statistics show that the number of infections per year has increased to over 150, 000 due to an increase in population of people living in Southern Arizona and Central California (Tabor, 2009). Historically, many have believed that people bearing the greatest risk of contracting coccidioidal infections were the farmers, construction workers, and archaeologists. However, healthy persons who get exposed to high doses of coccidioidal spores are also at risk of getting infected. The nature of coccidioidal infections in the majority of persons is either asymptomatic or subclinical making it difficult to know the actual incidence. In United States alone, an estimate of 25,000 new clinically proved cases of coccidioidal infections are reported annually. Out of these new infections, an estimate of 75 deaths occurs per year. Studies indicate that over 80% of residents living in endemic areas will test positive for coccidioidal infections after five years of stay in the endemic regions (Booth, 2000). Over the past several decades, a number of sharp upsurges in coccidioidal infections have occurred. During the western migration of the 1930s and the military influx of the 1940s, a significant increase in coccidioidal infections was noticed. However, a real epidemic was not experienced until 1978 when an unexpected dust storm struck endemic regions of United States (Friis & Sellers, 2009). California experienced a coccidioidal epidemic in 1991-1994. In 1992, the epidemic was at its peak producing approximately 4200 cases, which was an increase of over 14 fold from baseline. The epidemic occurred after a 5 year drought that had struck the endemic region and was suddenly terminated by short rainfalls (Tabor, 2009). Occurrence of the short rains allowed the arthrospore to germinate and disperse when the summer winds struck. In areas that have the highest endemicity, infection rates are approximately 2-4% per year. However, prevalence in endemic regions varies from time to time. In endemic regions of California and Arizona, 30-40% of populations living in these regions get infected annually (Friis & Sellers, 2009). Cases of coccidioidomycosis in endemic regions are highest during the late summer, and in early rainfalls, after the soils dry up. The spread of the infectious agents usually begins after tampering with the soils, which may occur naturally or through human activities. Such occurrences increase the level of infectious agent in the air that is easy to inhale leading to infection (Booth, 2000). The 1994 Northridge earthquake that occurred in California is documented as one of the factors that caused coccidioidomycosis outbreaks of that year. Arizona has the highest prevalence of coccidioidomycosis, which are symptomatic in nature. In the state of Arizona, over 5,000 cases occur annually. A steady increase in prevalence has emerged since 1990 where 7 cases per 100,000 persons were reported in 1990, 15 cases per 100,000 persons in 1995 and an estimated 75 cases per 100,000 persons in 2007 (Tabor, 2009). Continued surveillance on cases of coccidioidomycosis point out that the infection do occasionally occur, especially after events that loosen up large quantities of soils (Friis & Sellers, 2009). Last experienced outbreaks occurred among military trainees, archeologists, and people living in the earthquake and dust storm struck endemic regions. In the endemic regions, coccidioidomycosis has had significant socioeconomic impacts on those regions. Healthy persons diagnosed with symptomatic condition are likely to miss school or work more than once in a month. In the recent past, costs of antifungal drugs for the treatment of coccidioidomycosis have risen to a range of $5000-$20,000 per person per annum. In Arizona, scholarship athletes attending their train in that region frequently get coccidioidal infections, which further complicate their performance on truck (Friis & Sellers, 2009). Interventional measures Over time, coccidioidomycosis has proved to be a difficult condition to deal with in the endemic regions. However, various interventions are currently in use in an attempt to reduce airborne dust that leads to the occurrence of the infections (Acton, 2011). Majority of the interventions have focused on controlling dust through paving dusty roads, seeding lawns as well as dampening dust with oil. These interventions have shown positive results in reducing incidences of coccidioidomycosis in military personnel. People at high risk of getting the infection have managed to thrive in endemic regions through the use of prophylactic treatment. During organ transplant procedures conducted in endemic regions, medical experts conduct thorough screening programs for coccidioidomycosis (Acton, 2011). Status of the disease and treatment today Currently, medical researchers are working hard to develop a vaccine that can offer immunity to populations living in endemic regions (Booth, 2000). To date, there is no any available vaccine, but studies from previous infections show that it is possible to get a vaccine to offer immunity against coccidioidomycosis. People living in endemic regions have some preventative measures that enable them reduce the chances of getting the infection. Some of the measures include the use of N95 mask while working construction zones, avoiding activities that cause the disturbance of soils, use of air filters such as HEPA filters within houses, taking prophylactic antifungal drugs, and thorough cleaning of wounds, especially when exposed to dust (Tabor, 2009). HIV/AIDS infections increase the risk of getting coccidioidomycosis. Therefore, HIV positive persons should keep off from endemic environments in order to avoid contracting the infection (Booth, 2000). Treatment There is a wide range of antifungal medications that are available for the treatment of coccidioidomycosis. Azoles such as fluconazole, itraconazole and ketoconazole, as well amphotericin B, are effective in the treatment of coccidioidomycosis. Other interventions include surgical removal of affected lung tissues and it is effective in cases systemic infections or enlarged pulmonary cavitary (Friis & Sellers, 2009). References Acton, Q. A. (2011). Mycoses: Advances in Research and Treatment: 2011 Edition, ScholarlyBrief. Atlanta: Scholarly Editions. Booth, S. J. (2000). Microbiology: Pearls of Wisdom. Sudbury: Jones & Bartlett Learning. Clemons, K. V. (2007). Coccidioidomycosis: Sixth International Symposium, Volume IV. Birmingham: Blackwell Pub. Friis, R. H. & Sellers, T. A. (2009). Epidemiology for Public Health Practice. Massachusetts: Jones & Bartlett Learning. Tabor, J. A. (2009). Epidemiological Study of Coccidioidomycosis in Greater Tucson, Arizona. Michigan: ProQuest. Read More