Waterborne Diseases

Shigellosis pertains to the bacterial infection caused by the pathogen Shigella spp. The infection generally results in a severe condition characterized by diarrhea, as well as abdominal cramps (Geo et al. , 2007). The infection may become life-threatening if the medical attention is not given to the patient immediately. Shigellosis is still currently considered as a public health concern because it is often reported in places where poor hygiene and unsafe practices are implemented with regards to water supply.

The bacteria species Shigella only affects human beings and thus it is important that this pathogen be detected and controlled as soon as possible. Shigella is taxonomically classified under the family Enterobacteriaceae, which are small Gram-negative bacteria. This bacterial species is classified further into four serotypes, based on the lipopolysaccharide moiety on its cell membrane, namely S. dysenteriae, S. flexneri, S. boydii and S. sonnei.

The case report involving toddlers developing gastroenteritis after visiting a local water park is most possibly caused by S.dysenteriae, as this bacterium has already spread around the world. Shigellosis has been reported to generally affect children, with the highest incidence among toddlers of approximately one to four years old (Niyogi, 2005). The infection is often observed to be more complicated if the infected child is malnourished because the bacterium may cause dysfunctional nutritional pathways, as well as a recurrence to the infection. The bacterium may also trigger the retardation in the growth of the child.

Aside from these bacterial infections from unhygienic water supply, the Shigella bacteria may also be transmitted in day care centers, as well as during migration to developing countries where hygienic practices are generally substandard. Shigella may also be transmitted between homosexuals (Watson, 2005). The major route of transmission of this bacterium is through the fecal-oral route. Shigellosis can be received from a very small amount of inoculum and thus this bacterial infection is highly transferable and contagious.

The main symptom for shigellosis is diarrhea and thus it is important to determine whether an individual has shigellosis. Improper handling of food and water products is the common route for the transmission of the bacteria and this is one of the features of the case study involving the toddlers suffering from gastroenteritis after visiting a water park. The bacterium has the ability to survive in water and food items and thus its propagation to humans can be easily completed.

The Shigella bacteria can also be further propagated through insect vectors such as flies that have been in contact with fecal material that has not been properly disposed. The common housefly can then come in contact with food or water products that are left exposed or uncovered. All humans can be infected by this bacterium, yet there are particular individuals that appear to be at an increased susceptibility to be infected with this bacterial pathogen. The incident report of gastroenteritis among at least 30 young children who visited a local water park represents approximately 44% of the total visitors of the park.

This high figure can render this infection as an epidemic because it has affected a huge proportion of the visiting population of the local water park (Global Health Council, 2009). The incubation period of Shigella has been determined to be within the range of 1 – 4 days after exposure to contaminated water or food. It may also be possible that the incubation can reach 8 days after exposure to unclean water or food. Symptoms of the infection include simple to severe diarrhea and this is due to the ingestion of the bacteria through the mouth.

The infected child may progressively present from the symptom of diarrhea to bloody feces, as well as abdominal cramps. In severe cases, dysentery is observed, which is characterized by scant amount of fecal matter, yet with higher frequency within the day. It is possible that the individual may have as frequent as 20 bowel movements in one day. The child may also lose approximately 300 milliliters of serum protein through the bowel movement. This loss may trigger the significant loss of nitrogen resources in the body, resulting in malnutrition, as well as growth retardation.

The patient may also experience a loss in his immune response, resulting in an increased incidence in other infectious disease and ultimately, death. An infection person with Shigella may be initially observed to undergo anorexia, which is specifically associated with extreme malnutrition. Aside from intestinal symptoms, shigellosis may also be associated with seizures, which results from high fever. It is also possible that the patient experiences anemia and this is due to the toxins that the bacterium has produced inside the body (Sansonetti, 2001).

Among healthy individuals, shigellosis is generally observed to be self-limiting, wherein the person recovers from the infection within five to seven days. However, if a malnourished child is infected, the symptoms are usually more complicated due to the lack of nourishment and poor immune reaction to the infection. This often occurs among children from developing countries and these young patients are dehydrated and hypoglycemic. It is also possible that a prolapse of the rectum could occur among these individuals, as well as perforation of the intestinal wall.

Among individuals infected with the human immunodeficiency virus (HIV), Shigella may enter the bloodstream, resulting in bacteremia. Since these individuals carry a compromised immune system, the symptoms of this infection become more severe and even deadly. The bacterium may also cause arthritis, as well as urethritis or Reiter’s syndrome. It is thus important that control measures and the appropriate antimicrobial treatment be immediately provided to patients showing the symptoms of Shigella infection. The disease is actually treatable, yet can still be deadly if left unattended.

As an epidemiologist, it is important to determine which specific pool in the water park has caused this bacterial infection among the young children. Water samples from each pool will be collected and brought to the laboratory for testing for microbial pathogens. The water samples will be streaked onto agar plates and kept for a few days for incubation. It is expected that if bacteria is present in the water, it will grow on these agar plates because these contain nutrients that are optimal for bacterial growth. Once bacterial colonies arise on the agar plate, a colony will be scraped out and tested for Gram staining.

Shigella is a Gram-negative bacterium and thus additional tests will also be conducted in order to further characterize and differentiate this species from Escherichia coli. These two bacterial species belong under one family, yet Escherichia coli is less damaging to the human body. In addition, the sugar moiety on the cell membrane of Shigella may positively identify this bacterial species. In order to control future epidemics of Shigellosis, it is important that clean water be used in all activities including cooking and swimming.

Proper waste disposal, especially for feces, should also be implemented. In the case of developing countries, it is important that fecal matter be hygienically handled and thus proper toilet facilities should be constructed in strategic areas. More importantly, the public should be educated with regards to proper hygiene. Information could be dissemination through the media and the simple tips should be explained, such as washing hands after using the toilet and before and after handling food.

Lactating mothers can also be encouraged to breast feed their babies in order to do away with the use of feeding bottles that may be improperly washed and even not sterilized. Breastfeeding can also equip the infant with antibodies that are important in conquering any bacterial exposures that the infant may encounter as he goes through growth and development. Since infection with Shigella generally results in diarrhea or dysentery, it is important that the public be educated with regards to oral rehydration measures which will replenish the lost fluids of the child.

The loss of significant amounts of water from the body can result in dehydration and in severe cases may cause the death of the patient. It is also important to educate mothers with regards to providing additional food to convalescing children because the nutrients in food may also help in making the child feel better and combat the current infection in their bodies. With regards to the operators of the water parks, it is important the routine chlorination of the water be conducted in order to disinfect the pools and prevent future epidemics (Sur et al.

, 2004). The water in the pools should also be routinely changed in order to prevent any new bacteria to further proliferate in the pools. The operators may also hire microbiologists who could regularly test the water of each pool and determine whether the pool is safe for swimmers, both young and old. The bacterium Shigella is commonly reported to infect young children because these individuals do not carry active immune systems that would react to pathogens that are present in the environment.

Adults are not affected by this bacterium because their immune system is already familiar with environmental exposures that that their immune system has built a battery of antibodies that could combat different types of foreign invaders of the human body. It is thus a general observation that individuals with poor immune systems, such as young children and human immunodeficiency virus (HIV) patients, have higher risks of being infected with this microbial pathogen.

It has also been reported that Shigella may also cause immunity in the human body. This may occur in places wherein the bacteria is commonly present in the environment and the exposure to this microbe for at least five years may result in an immune body, wherein the individual will not suffer from gastroenteritis regardless of the incorporation of the bacteria in the food and water that this person consumes or uses (Hacker and Kaper, 2002). It is therefore suggested that immunity occurs when a continuous exposure to this bacterium happens.

Immunity can thus be observed in developing countries, as well as military camps which may involve chronic exposures to contaminated food and water, and the body has grown a certain immunity to combat the presence of these bacteria in their immediate environment. There are efforts in designing a vaccine that is specifically meant to protect individuals from Shigella (World Health Organization, 2009). The vaccine is based on the lipopolysaccharide or sugar moiety that is presented on the cell membrane of the bacterium.

The lipopolysaccharide is considered as the antigen that is detected in the human body and antibodies are produced based on the structural and chemical properties of this molecule. It has been reported that the immunization of young children with the vaccine has resulted in approximately 80% protection, wherein these children did not suffer from diarrhea or dysentery when exposed to possibly unclean water or food items. Conclusion The bacterium Shigella is a Gram-negative microbe that can cause shigellosis, which is characterized by diarrhea, fever and/or dysentery.

The microbial pathogen is often present in unclean water and food items and the route of entry into the human body is through the mouth. The main route of transmission of this bacterium is through the fecal-oral pathway, wherein poor toilet hygiene and improper techniques for food preparation may result in the spread of the bacteria to other individuals. It is thus important that proper hygiene and prevention measures be instilled in society, in order to prevent future outbreaks, as well as morbidity and mortality.


Geo, B. , Carroll, K. C. , Butel, J. and Morse, S. (2007). Medical Microbiology, 24th ed. Chicago: McGraw-Hill Medical, 832 pages. Global Health Council. (2009). Emergency response to cholera and shigella epidemics. Downloaded from http://www. globalhealth. org/news/article/4195on April 4, 2009. Hacker, J. and Kaper, J. B. (2002). Pathogenicity islands and the evolution of pathogenic microbes, Vol. 1. New York: Springer, 195 pages.

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