The fight against global warming and the need to enhance green initiatives mainly focuses on the ozone depression thus making it possible for some critics to question the existence of global warming. Changing the strategy and involving issues that directly connect the well-being of humans can result in changing the disbelief on the harms that human activities are propagating. The rampant water pollution by industries by dumping their wastes into the rivers or other water sources is a major cause of complex diseases that have escalated in the past decade. Waterborne diseases in the U.S. increased by more than 10% for the past three decades due to the unregulated dumping of wastes and the consumptions of the polluted water by humans (Zahran et al., 2018). However, unlike the waterborne diseases that caused gastrointestinal disorders, respiratory pathogens Legionella pneumophila currently dominate the complex waterborne ailments.
Legionella diseases (LD) have contributed to the rise of the hospitalization and costs of healthcare to over $1 billion as the complexity of the ailment means a person with the pathogen must seek medical care (Zahran et al., 2018). Legionella disease first came to the limelight in 1976 after an outbreak in Philadelphia after over 89 people accessed healthcare for respiratory ailments that were unknown at the time. The incident in Philadelphia discovered that the ailments were caused by bacteria naturally occurring in fresh water that was safe if ingested but caused respiratory disorders if inhaled. The pathogens belonged to the Legionella which is the only genus in the Legionellaceae family (Zahran et al., 2018). The family consists of more than 70 serogroups and 50 species which have about 20 disease-causing agents. However, Legionella pneumophila serogroup 1 was responsible for more than 90% of the LD. The shifting of Flint municipal water from Detroit Water and Sewerage Department (DWSD) to use the Flint River water resulted in an outbreak of LD which consisted of 89 cases and 13 deaths of the patients. The Genesee County in Flint, Michigan were comprising mainly of minorities complained about the odor and color of the water but the municipal government assured the residents that the water was safe for drinking. In 2014 and 2015 most of the studies and investigations on the impact of change the water source mainly focused on water contamination and the lead contamination (Zahran et al., 2018). The high lead content in the water would dominate the media and scholars but in 2016, scholars and water investigations reports demonstrated that the lead poisoning was not the only health issue that the water system caused because of the water contained above U.S. Environmental Protection Agency (EPA) chemical, bacteria, and metals (Zahran et al., 2018). It was evident that the water contained Legionella pneumophila pathogens thus explaining the increased patients over 50 years diagnosed with Legionella pneumonia.
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Thesis
The study intends to determine whether the change in water chemistry in Flint, Michigan lead to the 2015 outbreak of Legionella diseases, the correlation of the chemical markers with the increased Legionella bacteria in the water. Therefore this study uses the Flint outbreak incident as the base in analyzing the Legionella pneumophila pathogen, determining the factors that influence Legionella growth, and the characteristics of the bacteria. The study also focuses on the diseases and the markets of water chemistry tests and treatment that would mitigate LD.
Paper Arrangement
Following the introduction above that has provided the general understanding and trends associated with Legionella disease outbreak in the U.S., the next section is a brief historical background of the Flint Water System. It also reviews the chemical composition of pipes carrying the water to the city and the effects of the changes in the sources of the water. The section is vital since it helps determine the impact of the chemical composition on Legionella growth discussed in chapter three.
Chapter four analyzes the steps that the city health officials failed to implement to prevent the outbreak. The next section discusses the characteristics of Legionella bacteria. This part includes the review of gram stain, shape, special growth habits, aerotolerance, and virulence factors.
Chapter six explores Legionella diseases whereas chapter eight analyzes the markers of water chemistry, tests, and strategies to diminish the harm caused by the naturally occurring pathogen. Lastly, the conclusion details all the key points from the paper.
Historical Background
According to Masten, Davies, & McElmurry (2016), the Flint Water Works Company, a privately owned incorporation distributed the first Flint water in 1883. The City of Flint passed an ordinance that required lead pipes for all connections with any water mains in 1887. In 1912, the city government purchased the water company which enabled the city to treat the Flint River water with alum coagulation before sand filtration (Masten, Davies & McElmurry, 2016). In 1952, the City of Flint began the construction of a new treatment plant completed after two years but at the time the Flint River treatment included pre-chlorination, alum coagulation, softening by using lime-soda ash, carbonation, and filtration. These steps were then followed by adding polyphosphate to mitigate corrosion and post-chlorination. The additional carbon, ammonia and sodium chlorite after the above steps removed the taste and odor (Masten, Davies & McElmurry, 2016). The plant had increased from the 28 mgd rating in the 1930s to 59 mgd and a maximum overload capacity of 86 mgd. The water was 50th percentile pH, color, and turbidity of tap water being 10.3, 2 and 0.1 ppm respectively. The water noncarbonated and total hardness was 49 and 86 mg/Las CaCO3 respectively (Masten, Davies & McElmurry, 2016). However, in 1967 the City of Flint decided to purchase treated water from the Detroit Water and Sewage Department (DWSD) citing the need for sufficient quality water for the growing population. The study states that most scholars concur that the reason for choosing to purchase water from DWSD was because of the contamination caused by the unregulated dumping of industries’ waste in the Flint River (Masten, Davies & McElmurry, 2016). Even after the changes were made, the city maintained the Flint Water Service Center (FWSC) for backup treatment.
In 2013, the Flint officials joined the Karegnondi Water Authority (KWA) that was on the verge of constructing a pipeline from Lake Huron, the same source of water of the DWSD to help the City of Flint to own its facility and end the agreement with the DWSD (Masten, Davies & McElmurry, 2016). The city officials intended to use the DWSD as an interim source of water before the completion of the KWA but after the failure to reach an agreement led to the Flint officials choosing to use water from Flint River supplied under the FWSC. The move to use the Flint River as the source of community water faced critics due to the pollution of the water. However, even after the warnings from water investigators, the city implemented the shift of their water system from DWSD to the Flint River. The switch had immediate adverse effects as the residents complained about the odor, taste, and red color of the water. The red water was later associated with the corrosion of the iron pipes. General Motors would stop using the Flint River water arguing that the water was causing corrosion on its engines.
Chemical Composition and the Effects on the Pipes
Investigations in 2014 discovered the presence of E. coli and violation of other EPA requirements by the Flint officials. The officials would adopt the issuance of three boil-water alerts in the summer of 2014. Lee Ann Walters discovered the lead in her home water which had a concentration of 104 μg/L (Schwake, Garner, Strom, Pruden & Edwards, 2016). The U.S. EPA requires the lead concentration to be below 15 μg/L. Further investigation demonstrated that in over 120 samples from Flint homes the lead concentration was above 30 μg/L. These findings would dominate most studies with children having an increase of 2.5 blood lead levels since the switch.
The city switched back to DWSD as their supplier with the water having 1 mg/L phosphorus to inhibit corrosion but that switch did not reduce the lead levels. Therefore, the FWSC increased ~2.5 mg/L phosphoric acid to diminish the corrosion (Zahran et al., 2018). However, the only significant change was not an adverse effect of the water as Legionella diseases increased from six deaths to 13 and a total of about 89 cases of infections. The removal of the Bench-scale jar testing for trihalomethane (THM) removal made it difficult for investigators to determine the chemical dosage between January and August 2015 thus raising alarms over the reasons for such negligence (Zahran et al., 2018). However, several meaningless changes in a chemical dosage such as the addition of the anionic polymer to the lime softening from 0.05 mg/L to concentrations exceeding the 1.0 mg/L NSF International recommendations. The ozone dosage was unclear whereas the bromate levels were between 0 and 23 μg/L (Zahran et al., 2018). The lack of most dosage levels depicts that bromate levels were likely to be above the MCL of 10 ppb. The FWSC used gaseous chlorine for disinfection with a dosage ranging from ~5 mg/L to 7 mg/L in winter and summer respectively.
The absence of post-chlorination and pre-filter chlorination after August 3, 2015, and the softening bypass steam dropped the chlorine and by 2015 the chlorine levels dropped by 20% to the levels in 2014 (Schwake, Garner, Strom, Pruden & Edwards, 2016). The low levels of chlorine during the switch from DWSW to Flint River led to the detection of the E. coli. The city would increase the chlorine to eliminate the E. coli making piped water to have more chlorine than that from the treatment plant. This action spiked the rate of corrosion in the iron pipes connecting to the homes and hospitals. The change in pH during the switches led to the softening of iron tubercles thus increasing the level of corrosion.
Impacts of the Changes described above on Legionella growth
According to Schwake, Garner, Strom, Pruden & Edwards (2016), the switch to a corrosive portable water source interrupted the corrosion control thus leading to a high release of nutrients, iron and reduced chlorine residual promoted Legionella’s growth. The study argues that the loss of disinfectant residue considering that the FWSC added chlorine to the water from the plant was caused by the iron corrosion. The iron corrosion used most of the chlorine in chemical reactions rather than in disinfecting the water flowing into the homes (Schwake, Garner, Strom, Pruden & Edwards, 2016). The reactions and the reduced chlorine led to the increase of microbial nutrients in the water.
Based on the understanding that Legionella can inhabit other organisms such as amoebae, the increased rates of microbial nutrients enhanced the growth of the Legionella (Schwake, Garner, Strom, Pruden & Edwards, 2016). Lastly, the warm temperature provided the best breeding temperature of the Legionella pathogens. According to Dietersdolfer et al. (2018), water system engineered with elevated temperatures are the most suitable grounds for Legionella growth. The study depicted that the cooling showers, hot and cold water distribution and air conditioning systems are suitable for Legionella to colonize because they are naturally formed biofilms (Schwake, Garner, Strom, Pruden & Edwards, 2016). The lack of corrosion inhibitors due to the lack of any recorded ozone dosage proves that there were no inhibitors thus providing the needed surface for bacterial growth (Schwake, Garner, Strom, Pruden & Edwards, 2016). Samples corrected by investigators demonstrate that the Legionella grows rapidly in conditions with more iron than the chlorine because these conditions reduced the toxicity for microorganisms to develop.
Important Steps that should have been taken by the Flint Health Officials
According to Muylwyk, Sandvig & Snoeyink (2014), the shifting of the water sources and treatment changes was always going to escalate the corrosion of the pipes. The study argues that changes in pH, coagulant, the addition of new recarbonation, and use of lime that was never used in DWSW was always going to cause corrosion (Muylwyk, Sandvig & Snoeyink, 2014). The Flint health officials did not understand the treatments needed to ensure that the factors discussed above would remain unchanged. The city officials were also too lenient and negligent to approve the switch without undertaking a pilot study that would have demonstrated the effects of switching to a polluted river. The city officials ignored the EPA standards thus making it difficult to control corrosion in the aftermath.
The corrosion in General Motors provided the required insight for the officials to investigate the acidity of the water but due to reasons are only known to the leaders, such signs were ignored (Zahran et al., 2018). Negligence was the main reason for most decisions made but benchmarking and training the city officials would have ensured that these did not reach such magnitude. As earlier stated the FWSC increased phosphate to control lead corrosion after it was public that the water contained higher levels of lead but the added phosphate exceeded the recommendations because EPA investigators had stated that the Flint River was never close to being used as a community source of water due to its contamination (Zahran et al., 2018). The rush to end the DWSW agreement before the completion of the KWA was fatal thus making it clear that the only way to diminish the lead and iron corrosion was by changing the entire piping system.
Characteristics of Legionella
Legionella species are naturally occurring species with thin Gram-negative rods. The species is highly diverse and pleomorphic thus making it easier to exist in different environments. These bacteria tend to be naturally occurring in freshwater and soils and can remain alive in the air for more than 30 minutes. Their ability to inhabit amoebae and depend on the host makes them complex to analyze. However, the Legionella pneumophila belonging to monoclonal antibody group is responsible for over 90% of the LD. According to Arslan-Aydogdu and Kimiran (2018), studies on the Legionella virulence focus on type II and IV secretion systems.
The authors argued that type II Legionella secretion pathways were acid and alkali phosphatase, RNase, Phospholipase A and C activities, lipase, and protease (Arslan-Aydoğdu & Kimiran, 2018). Therefore, type II is responsible for the intercellular infection whereas type IV which contains type IVA and type IVB. Type IVA includes Legionella vir-homologues (Lvh) system whereas type IVB consists of defective organelle trafficking (dot) and intracellular multiplication (icm) as the secretory pathways. Thus the Lvh explains the infection of the bacteria or the ability of the Legionella to infect the host while the dot and icm explain the intracellular replication in the host’s cells. The macrophage infection potentiator (Mip) factor and a membrane-associated protein of 24kDA (Arslan-Aydoğdu & Kimiran, 2018). The Legionella has a special characteristic to convert to an avirulent status with a high frequency. The avirulent variations under specialized laboratory media demonstrated that the strain tends to have elongated cell shape, reduced serum resistance and survival in aerosols (Arslan-Aydoğdu & Kimiran, 2018). Being under monoclonal antibody group, Legionella attacks the host’s cells by replicating the intracellular monocytes and macrophages.
According to Dietersdorfer et al. (2018), Legionella strains can infect and replicate in human and amoebae macrophages. The starved viable but non-culturable (VBNC) Legionella strains used in the study demonstrated that they encounter a free-living amoeba (FLA) that is their natural host (Dietersdorfer et al., 2018). The Legionella is dependent on the amoebae for its existence in the different biofilms. The Legionella remains in the amoebae’s cells by using its adaptations that enable it to trigger the selection of grazing resistance. These factors enable the bacteria to avoid being digested by the amoebae while it replicates and exploits the host’s as its nutrients sources. These characteristics enable the Legionella to exist in different environments and once inhaled by the humans it bacteria encounter varied types of phagocytic cells in the lungs which are known as alveolar macrophages (Dietersdorfer et al., 2018). The Legionella uses the specialized adaptation to survive in the alveolar macrophages by replicating to the new host. The multiplication as earlier discussed results in Legionella disease if the Legionella multiplies in an elderly or immunocompromised individual.
Diseases
As stated above, humans inhale Legionella in water droplets making it easier to reach the lungs as inhaled air. Once in the lungs it uses its outer Mip and coats itself with complement C3 (Dietersdorfer et al., 2018). Once in the alveolar macrophages, it inhibits fusion for a period of 2 to 14 days which enabled it to grow to and kill the macrophages by triggering apoptosis by secreting pore-forming toxins (Dietersdorfer et al., 2018). The multiplicity of the Legionella causes Legionella disease at the terminal of the alveoli and bronchioles. The main symptoms are coughing, chest pains, headache, chills, and fever. Other illnesses can lead to liver failure if untreated. The Legionella pneumonia is fatal but similar symptoms without pneumonia, Pontiac fever, disappears without any treatment. It is essential to note that Legionella diseases are not contagious and the only way of getting the legionella pneumonia is through inhaling contaminated droplets. Most people are easily cured by taking antibiotics apart for when a person suffers from liver failure and is attacked by the bacteria. The rates of death for such a patient increased by 15% (Dietersdorfer et al., 2018). Other complications involve respiratory failure, septic shocks and kidney failure leading to increased carbon dioxide, reduced blood flow and accumulating wastes in the body respectively.
Markers of Water Chemistry
In most studies reviewed on legionella’s growth, temperatures between 25-45 0 C with an optimal between 32-42 0 C facilitates the bacteria growth and multiplicity hence the preference of the bacteria to colonize cooling towers of hot and cold water systems. However, the bacteria can survive for less than an hour in environments of 50 0 C to 60 0 C (Schwake, Garner, Strom, Pruden & Edwards, 2016). The corrosion of the pipes also facilitates the multiplicity of the bacteria with the corrosion creating biofilms for the Legionella. Water chemistry entails the treatment of water in accordance with the DEP regulations. The DEP requires that thermal and chlorination of community water is within the safe drinking levels. Therefore hitting the water to higher temperatures of about 50 0 C eliminates the likelihood of the Legionella in the water. The heating regulations argue that the temperatures should be determined by the distance from the source of the water to the exit. Therefore, 50 0 C should be the temperature at the exit (Schwake, Garner, Strom, Pruden & Edwards, 2016). The DEP also states that super-chlorinated water must be flashed and should not be used for human consumption. These guidelines depict that thermal and chemical compositions are markers for Legionella growth but maintain the stated requirement would diminish the growth of Legionella.
Conclusion
Legionella diseases increase in Flint after the water switch was due to the changes that increased corrosion, phosphate acidity and alkalinity which are suitable for the bacteria to multiply. The study demonstrated that Legionella has specialized Mip proteins that enable it to infect the host cells without being digested, replicating and destroying the host cells. Although the fatality of legionella is significantly low it is clear that water safety is an important issue to enhance the health of the population. The study demonstrated that the Legionella is specialized to infect human cells with the possibility of causing organ failures, therefore, enhance water safety is vital to eliminate the markers of water chemistry that promote the bacteria growth.
References
Arslan-Aydoğdu, E., & Kimiran, A. (2018). An investigation of virulence factors of Legionella pneumophila environmental isolates. Brazilian Journal Of Microbiology , 49 (1), 189-199.
Dietersdorfer, E., Kirschner, A., Schrammel, B., Ohradanova-Repic, A., Stockinger, H., & Sommer, R. et al. (2018). Starved viable but non-culturable (VBNC) Legionella strains can infect and replicate in amoebae and human macrophages. Water Research , 141 , 428-438.
Masten, S., Davies, S., & McElmurry, S. (2016). Flint Water Crisis: What Happened and Why? Journal - American Water Works Association , 108 , 22-34.
Muylwyk, Q., Sandvig, A., & Snoeyink, V. (2014). Developing Corrosion Control for Drinking Water Systems. Opflow , 40 (11), 24-27.
Schwake, D., Garner, E., Strom, O., Pruden, A., & Edwards, M. (2016). Legionella DNA Markers in Tap Water Coincident with a Spike in Legionnaires’ Disease in Flint, MI. Environmental Science & Technology Letters , 3 (9), 311-315.
Zahran, S., McElmurry, S., Kilgore, P., Mushinski, D., Press, J., & Love, N. et al. (2018). Assessment of the Legionnaires’ disease outbreak in Flint, Michigan. Proceedings Of The National Academy Of Sciences , 115 (8), E1730-E1739.
