Infectious Disease Found in the Developing World: Typhoid Fever - Research Paper Example

Typhoid Fever Typhoid fever, according to the World Health Organization (WHO, 2009) is a bacterial disease caused by Salmonella typhi. It is also known as enteric fever. If left untreated, this disease can potentially be fatal. Typhoid fever is extremely rare in developed nations, but has a high incidence in developing countries where sanitation is often very poor. This paper shall discuss the causes, the disease process and the different available intervention measures for this disease. Causative Agent Typhoid fever is caused by the bacteria Salmonella enterica typhi or simply Salmonella typhi. It is described as an obligate parasite with humans as its natural reservoir. Salmonella typhi is a gram-negative bacterium from the family Enterobacterioceae. It is a “multi-organ pathogen that inhabits the lymphatic tissues of the small intestine, liver, spleen, and bloodstream of infected humans” (Pollack, 2003). It does not usually inhabit or infect animals and the bacterium is most common in developing nations where sanitation is poor and there is limited supply of antibiotics. It is also described as a motile and facultative anaerobe which is very much susceptible to the action of antibiotics. There are about 107 strains of this bacterium which have already been isolated. Many of these strains have different metabolic characteristics and degrees of virulence; some of them are multi-drug resistant. Scientists studying this bacterium narrate that it contains the typical endotoxin expected of Gram-negative microorganisms as well as the Vi antigen which usually increases the virulence of the bacterium. It is also known to excrete ‘invasin’, a protein that lets non-phagocytic cells take the bacterium, and later enables it to live inside the cell. This ‘invasin’ sometimes also prevents the oxidative burst of leukocytes, thereby preventing the innate immune response to the bacterium (Pollack, 2003). Disease Transmission and Incubation Period Typhoid fever is transmitted through the oral-fecal route. It is transmitted orally through food which is handled by an individual who frequently sheds the salmonella typhi bacterium through his stool or sometimes through his urine. The hand-to-mouth transmission is also possible “after using a contaminated toilet and neglecting hand hygiene” (Brusch, et.al., 2008). It may also be transmitted through sewage contaminated water ingested by humans. Shellfish which is taken from contaminated water, raw fruits and vegetables which are fertilized with contaminated sewage are also possible contaminants. High incidence rates are seen in largely populated areas where water supplies are contaminated with feces. Waterborne transmission usually involves small inocula, whereas foodborne transmission usually has larger inocula and higher attack rates (World Health Organization, 2003). Persons recovering or who have recovered from the disease may be asymptomatic carriers and with poor hygiene, they may pass on the disease to other people through the food they handle. The case of Mary Mallon may be recalled because she was one of the more well-known asymptomatic carriers of the disease. Considering the modes of transmission mentioned above, typhoid fever is common in developing nations because many of these countries have improper or non-existent sewerage systems. Their waterworks also lack proper decontamination or filtration processes. This makes the possibility of their water systems being contaminated with feces high, thereby increasing the possibility of disease transmission. Also, in nations “where open sewerage is accessible to flies, the insects land on the sewage, pick up the bacteria, and then contaminate food to be eaten by humans” (Gale Encyclopedia of Medicine, 2008). The incubation period for the disease is 10-20 days depending on the size of the bacteria (Easmon, 2005). The bacteria usually survive ingestion by the phagocytes and multiply within these cells. When their numbers increase, they now spill out of the cell and enter the bloodstream (Brusch, 2008). Infections with smaller bacteria can have longer incubation periods. Larger bacteria spill out of the cells at shorter time intervals causing earlier manifestation of the disease. In some instances fever can manifest 7-14 days after contact with the bacteria (Brusch, 2008). Disease process or course Medical researchers Brusch, et.al., (2008) discuss the course of typhoid fever. They narrate that the fever that manifests in the patient during the first week may be described as stepwise, that is, it usually increases over the course of each day and then drops at each subsequent morning. They also discuss that during the first week, gastrointestinal manifestations (abdominal pain and tenderness) of the disease develop. The monocytic infiltration causes the Peyer’s patches to inflame, thereby also causing the bowel lumen to narrow. This leads to constipation felt throughout the duration of the illness. During this first week, the patient is likely to develop a dry cough, dull frontal headache and increasing malaise. At about the end of the first week of the illness, the patient usually develops salmon-colored rose spots which are about 1-4 cm in diameter. These usually disappear in about 2-5 days. The researchers further describe that during the second week of the illness, the above-mentioned symptoms progress, the abdomen becomes distended, and soft spleenomegaly is usually seen. There is also bradycardia. At the third week, the patient becomes toxic and sometimes anorexic, exhibiting significant weight loss. The conjunctivae are sometimes infected, the patient is tachypneic, has a thready pulse with crackles heard at the lung base. Some patients may have foul, green-yellow, and liquid diarrhea. The patient may also develop apathy, confusion, and sometimes psychosis. Infected Peyer’s patches can sometimes cause bowel perforation and peritonitis. If symptoms are untreated and are allowed to progress, the toxemia, myocarditis and hemorrhage may possibly bring the death of the patient. However, if the patient is able to survive his fourth week, the fever and the abdominal distention, along with the weakening mental state can improve in a few days. There may still be intestinal and neurologic complications in individuals who are untreated and the weakness felt by the patient may take months to overcome. Worldwide Mortality and Morbidity Rate The mortality rate of typhoid fever worldwide registers at 0.7 deaths per 1 million people or 622 deaths, with South Africa (195 deaths) coming in as the top-most nation with the highest number of deaths for this disease. It is followed by Mexico with 114 deaths; Thailand with 97 deaths; Peru with 56; Egypt with 50; Ecuador with 29; El Salvador with 22; Dominican Republic with 13; Brazil with 12 and Colombia rounding up the top ten with 10 deaths (World Health Organization, 2004). These rates are affected by reporting practices of countries; some of them do not report cases of deaths caused by typhoid fever and may indicate other causes of death in the patients’ death certificates. In general however, the results above reflect that most of the cases of deaths come from developing nations. The latest worldwide prevalence rate for typhoid fever is estimated at 16 million cases. Incidence rates per country extrapolated from incidence rates in the United States and Canada peg China as the country with the highest incidence rate of the disease followed by Indonesia (303 cases), Brazil (234 cases), Pakistan (202 cases, Russia (183 cases), Bangladesh (179 cases), Japan (161 cases), Philippines (109 cases), Vietnam (105 cases, and Germany (105 cases) (Wrong Diagnosis.com., 2009). These nations are mostly developing nations and highly populated. Understandably, under these odds, their infection and transmission rates are high. The more progressive nations like Japan, Germany and Russia have better treatment rates and better treatment options for their citizens. The developing nations do not have as much treatment options and supplies to treat their typhoid patients, therefore, their morbidity and mortality rates are higher as compared to developed nations. Characteristics of an at-risk host Studies have revealed that “antacids, histamine-2 receptor antagonists (H2 blockers), proton pump inhibitors, gastrectomy and achlorhydria decrease stomach acidity and facilitate S typhi infection” (Brusch, et.al., 2008). A host taking any of the medications listed above and who has had gastrectomy is at a greater risk of being infected with typhoid fever. Stomach gases can potentially kill bacteria which in turn prevents absorption of the bacteria in the intestines. Those who have HIV/AIDS are also at an increased risk of being infected with the disease because of their compromised immune systems. Studies however emphasize that this association is minor. Genetic polymorphisms of the PARK2 and PACGR, protein aggregates involved in breaking down bacterial signaling molecules, tend to dampen the macrophage response. These polymorphisms have been found in patients with Mycobacterium leprae and Salmonella typhi. Some mutations also exist to protect the host. The Salmonella typhi bacteria usually bind to cystic fibrosis transmembrane conductance receptor (CFTR), seen and expressed in the gastrointestinal tract membrane. About 2%-5% of white persons are heterozygous for mutation F508del of the CFTR which associates them with a lower risk for typhoid fever, cholera and tuberculosis. School-age children and young adults also have a higher risk of being infected with the disease because of their greater predilection for eating street foods, their increased contact with dirt, and their underdeveloped health consciousness (Brusch, et.al., 2008). People who live in developed nations like the United States place themselves at risk for contracting the disease when they travel to developing nations and do not take any precautions in the water they drink and in the food they eat. Most cases of typhoid fever in the United States indicate a history of travel prior to the disease infection. Environmental and behavioral risk factors The following instances are considered environmental and behavioral risk factors for typhoid fever: “eating food from street vendors, living in the same household with someone who has a new case of typhoid fever, washing the hands inadequately, sharing food from the same plate, drinking unpurified water, and living in a household that does not have a toilet” (Brusch, et.al., 2008). These risk factors are commonly seen in many developing nations stricken with poverty. Most of them have inadequate facilities and are likely to use pit privies for their comfort needs. They also have inadequate water supply, barely enough for them to drink and not enough for their hygiene and hand washing needs. People who work or travel in areas where typhoid fever is endemic are at increased risk for contracting the disease (Mayo Clinic Staff, 2008). During their travel they may unknowingly come in contact with carriers, with people afflicted with or recovering from the disease; or they may ingest food or water contaminated with Salmonella typhi. Prevention Measures: Environment In order to optimize the environment in preventing typhoid fever, adequate water treatment must be carried out on water supplies. People residing in third world nations should make sure that the water they are drinking has properly undergone the filtration process. They should avoid drinking water off the tap or drinking water from rivers, streams, or creeks. Water for drinking should be boiled in order to ensure that bacteria causing the disease are killed. Sewage systems must be closed. Pit privies must also be sealed and, if possible, converted to cleaner and more up-to-date facilities. Solid and liquid waste must also be properly disposed in covered garbage bins in order to prevent the spread of the disease through flies and other insects. Food must not be left uncovered in order to prevent contamination through flies (Lentnek, 2007). Gutters must be kept clean and covered in order to prevent swarming of flies and consequently prevent the spread of the bacteria. Surroundings and the immediate vicinity of households must always be kept clean and free from scattered garbage. A clean environment prevents swarming of flies and ultimately prevents the spread of the disease. Prevention Measures: Increasing the Host’s Resistance In order to increase the host’s resistance to the disease, he can have himself vaccinated. Typhoid fever vaccines are now available in oral and single-dose injection forms. Both forms of the vaccine are more or less equally effective and offer about 65% to 75% protection against the disease. The oral vaccine consists of four capsules taken every other day over the period of a week. It may be given as a first-time or a booster dose to the patient. Protection gained from this vaccine lasts for about 5 years and a booster dose is recommended after. This oral form is however not recommended for children below 6 years of age (Barnas, 2000). This vaccine is highly recommended for people in developed nations who have a travel destination in a developing country. The single-dose injectable vaccine is effective after 2-weeks of being injected and is effective for 2 years. Booster doses are recommended at 2-year intervals. This can be used in children as young as two years of age. A healthy diet of fruits and vegetables also helps increase resistance against this disease; however these fruits must be properly and thoroughly washed before they are eaten. Vegetables must also be properly peeled, washed, and cooked in order to remove and kill the bacteria that may be lodged in the peelings and the leaves (Wrong Diagnosis.com, 2009). Prevention Measures: Preventing contact with agent In order to prevent contact with the causative agent, various precautions may be taken. Contact with persons ill with typhoid fever must be avoided or at least minimized; and if contact cannot be avoided, persons in contact with typhoid fever patients must wash their hands thoroughly while living with the patient. The patient must not be allowed to handle food for other people in order to prevent the spread of the bacteria and the contamination of food items. Eating street foods and beverages must also be avoided in order to decrease possibility of contracting the disease through contaminated foods. It is impossible to ensure that street food handlers would be sanitary and hygienic in handling and preparing the food, therefore, it is best to completely avoid ingesting street foods. Food prepared in restaurants and other food establishments without the necessary health permits and clearances must also be avoided. Food must be thoroughly cooked and when eating in food establishments, food which does not appear to be freshly cooked and steaming must be avoided. As much as possible, food must be personally prepared and handled in order to ensure that proper precautions to keep the food clean are taken (Wrong Diagnosis.com., 2009). Hand washing techniques must be integrated into the lives of people in the developing nations despite limited facilities and water supply. This simple precaution is very much based on personal hygiene and vigilance one’s health. These precautions do not cost much money, and can easily be adopted in developing nations in order to decrease the prevalence of the disease. Works Cited Background Document: The diagnosis, treatment and prevention of typhoid fever. (May 2003) World Health Organization. Retrieved 04 May 2009 from http://whqlibdoc.who.int/hq/2003/WHO_V&B_03.07.pdf Barnas, G. (31 August 2008) Typhoid Fever Vaccines. Medical College of Wisconsin Healthlink. Retrieved 04 May 2009 from http://healthlink.mcw.edu/article/907107823.html Brusch, J., et.al., (3 December 2008) Typhoid Fever. Medscape. Retrieved 04 May 2009 from http://emedicine.medscape.com/article/231135-overview Easmon, C. (4 January 2005) Typhoid fever and paratyphoid fever. Netdoctor. Retrieved 04 May 2009 from http://www.netdoctor.co.uk/travel/diseases/typhoid.htm Lentnek, A. (20 June 2007) Typhoid Fever-Prevention. University of Maryland. Retrieved 04 May 2009 from http://www.umm.edu/ency/article/001332prv.htm Noble, J., et.al., (2006) Mexico. New York: Lonely Planet Publishers. Pollack, D. (30 September 2003) Salmonella enterica typhi. University of Connecticut Department of Molecular and Cell Biology. Retrieved 04 May 2009 from http://web.uconn.edu/mcbstaff/graf/Student%20presentations/Salmonellatyphi/Salmonellatyphi.html Prevalence and Incidence of Typhoid Fever (2009). Wrong Diagnosis.com. Retrieved 04 May 2009 from http://www.wrongdiagnosis.com/t/typhoid_fever/prevalence.htm Typhoid Fever (2008) Gale Encyclopedia of Medicine. Retrieved 04 May 2009 from http://medical-dictionary.thefreedictionary.com/typhoid+fever Typhoid Fever (2009) World Health Organization. Retrieved 04 May 2009 from http://www.who.int/topics/typhoid_fever/en/ Typhoid Fever Prevention (2009) Wrong Diagnosis.com. Retrieved 04 May 2009 from http://www.wrongdiagnosis.com/t/typhoid_fever/prevent.htm Typhoid Fever Risk Factors (10 April 2008) Mayo Clinic. Retrieved 04 May 2009 from http://www.mayoclinic.com/health/typhoid-fever/DS00538/DSECTION=risk-factors Read More