Shigellosis

Shigellosis
Synonyms Bacillary dysentery, Marlow syndrome
Shigella seen in a stool sample
Specialty Infectious disease
Symptoms Diarrhea, fever, abdominal pain[1]
Complications Post infectious arthritis, sepsis, seizures, hemolytic uremic syndrome[1]
Usual onset 1-2 days post exposure[1]
Duration 5-7 days[1]
Causes Shigella[1]
Diagnostic method Stool culture[1]
Prevention Handwashing[1]
Treatment Drinking fluids and rest[1]
Medication Antibiotics (severe cases)[1]
Frequency >80 million[2]
Deaths 700,000[2]

Shigellosis is a type of diarrhea caused by a bacterial infection with Shigella. Symptoms generally start one to two days after exposure and include diarrhea, fever, abdominal pain, and pain with passing stool. Blood may be present in the stool. Symptoms typically last five to seven days. Complications can include post infectious arthritis, sepsis, seizures, and hemolytic uremic syndrome.[1]

Shigellosis is caused by four specific types of Shigella.[2] These are typically spread by exposure to infected feces. This can occur via contaminated food, water, or hands. Contamination may be spread by flies or when changing diapers. Diagnosis is by stool culture.[1]

Prevention is by properly washing the hands. There is no vaccine. Shigellosis usually resolves without specific treatment. Sufficient fluids by mouth and rest is recommended. Bismuth subsalicylate may help with the symptoms; however, medications that slow the bowels such as loperamide are not recommended. In severe cases antibiotics may be used but resistance is common. Commonly used antibiotics include ciprofloxacin or azithromycin.[1]

Globally shigellosis occurs in at least 80 million people and results in about 700,000 deaths a year. Most cases occur in the developing world.[2] Young children are most commonly affected. Outbreaks of disease may occur in childcare settings and schools. It is also relatively common among travelers. In the United States about half a million cases occur a year.[1]

Signs and symptoms

Signs and symptoms may range from mild abdominal discomfort to full-blown dysentery characterized by cramps, diarrhea, with slimy-consistent stools, fever, blood, pus, or mucus in stools or tenesmus.[3] Onset time is 12 to 96 hours, and recovery takes 5 to 7 days.[4]

Infections are associated with mucosal ulceration, rectal bleeding, and drastic dehydration. Reactive arthritis and hemolytic uremic syndrome are possible sequelae that have been reported in the aftermath of shigellosis.

Shigella can be transmitted through food, including salads (potato, tuna, shrimp, macaroni, and chicken), raw vegetables, milk and dairy products, and meat. Contamination of these foods is usually through the fecal-oral route. Fecally contaminated water and unsanitary handling by food handlers are the most common causes of contamination. Apart from hand-to-mouth infection, shigellosis is transmitted through fomites, water and mechanical vectors like houseflies.

The most common neurological symptom includes seizures.[5]

Diagnosis

The diagnosis of shigellosis is made by isolating the organism from diarrheal fecal sample cultures. Shigella species are negative for motility and are generally not lactose fermenters, but S. sonnei can ferment lactose.[6] They typically do not produce gas from carbohydrates (with the exception of certain strains of S. flexneri) and tend to be overall biochemically inert. Shigella should also be urea hydrolysis negative. When inoculated to a triple sugar iron slant, they react as follows: K/A, gas -, and H2S -. Indole reactions are mixed, positive and negative, with the exception of S. sonnei, which is always indole negative. Growth on Hektoen enteric agar produces bluish-green colonies for Shigella and bluish-green colonies with black centers for Salmonella.

Prevention

Simple precautions can be taken to prevent getting shigellosis: wash hands before handling food and thoroughly cook all food before eating. The primary prevention methods are improved sanitation and personal and food hygiene, but a low-cost and efficacious vaccine would complement these methods.[7]

Since shigellosis is spread very quickly among children, keeping infected children out of daycare for 24 hours after their symptoms have disappeared, will decrease the occurrence of shigellosis in daycares.[8]

Vaccine

Currently, no licensed vaccine targeting Shigella exists. Several vaccine candidates for Shigella are in various stages of development including live attenuated, conjugate, ribosomal, and proteosome vaccines.[7][9][10] Shigella has been a longstanding World Health Organization target for vaccine development, and sharp declines in age-specific diarrhea/dysentery attack rates for this pathogen indicate that natural immunity does develop following exposure; thus, vaccination to prevent the disease should be feasible. Shigellosis is resistant to many antibiotics used to treat the disease,[11] so vaccination is an important part of the strategy to reduce morbidity and mortality.[7]

Treatment

Treatment consists mainly of replacing fluids and salts lost because of diarrhea. Replacement by mouth is satisfactory for most people, but some may need to receive fluids intravenously. Antidiarrheal drugs (such as diphenoxylate or loperamide) may prolong the infection and should not be used.[12]

Antibiotics

Antibiotics should only be used in severe cases or for certain populations with mild symptoms (elderly, immunocompromised, food service industry workers, child care workers). For Shigella-associated diarrhea, antibiotics shorten the length of infection,[13] but they are usually avoided in mild cases because many Shigella strains are becoming resistant to common antibiotics. Furthermore, effective medications are often in short supply in developing countries, which carry the majority of the disease burden from Shigella. Antidiarrheal agents may worsen the sickness, and should be avoided.[14]

In most cases, the disease resolves within four to eight days without antibiotics. Severe infections may last three to six weeks. Antibiotics, such as trimethoprim-sulfamethoxazole, ciprofloxacin may be given when the person is very young or very old, when the disease is severe, or when the risk of the infection spreading to other people is high. Additionally, ampicillin (but not amoxicillin) was effective in treating this disease previously, but now the first choice of drug is pivmecillinam.[15]

The severity of the symptoms and the length of time the stool contains Shigella are reduced with antibiotics. However, many strains of Shigella are becoming resistant to common antibiotics, and effective medications are often in short supply in developing countries.[5]

Epidemiology

Insufficient data exist,[16] but it is estimated to have caused the death of 34,000 children under the age of five in 2013, and 40,000 deaths in people over five years of age.[7] Shigella also causes about 580,000 cases annually among travelers and military personnel from industrialized countries.[17]

An estimated 500,000 cases of shigellosis occur annually in the United States.[11] Infants, the elderly, and the critically ill are susceptible to the most severe symptoms of disease, but all humans are susceptible to some degree. Individuals with acquired immune deficiency syndrome (AIDS) are more frequently infected with Shigella.[18] Shigellosis is a more common and serious condition in the developing world; fatality rates of shigellosis epidemics in developing countries can be 5–15%.[19]

Orthodox Jewish communities (OJCs) are a known risk group for shigellosis; Shigella sonnei is cyclically epidemic in these communities in Israel, with sporadic outbreaks occurring elsewhere in among these communities. "Through phylogenetic and genomic analysis, we showed that strains from outbreaks in OJCs outside of Israel are distinct from strains in the general population and relate to a single multidrug-resistant sublineage of S. sonnei that prevails in Israel. Further Bayesian phylogenetic analysis showed that this strain emerged approximately 30 years ago, demonstrating the speed at which antimicrobial drug–resistant pathogens can spread widely through geographically dispersed, but internationally connected, communities." [20]

See also

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 "General Information| Shigella – Shigellosis | CDC". www.cdc.gov. 3 August 2016. Retrieved 20 April 2017.
  2. 1 2 3 4 Guidelines for the control of shigellosis, including epidemics due to Shigella dysenteriae type 1 (PDF). WHO. 2005. p. 2. ISBN 924159330X. Retrieved 20 April 2017.
  3. ↑ "Shigellosis". The Merck Manual Home Health Handbook. Retrieved 10 February 2012.
  4. ↑ "Symptoms Of Shigella Infection". About Shigella. Marler Clark. Retrieved 10 February 2012.
  5. 1 2 "Diarrhoeal Diseases: Shigellosis". Initiative for Vaccine Research. World Health Organization. Retrieved 11 May 2012.
  6. ↑ Ito, Hideo; Kido, Nobuo; Arakawa, Yoshichika; Ohta, Michio; Sugiyama, Tsuyoshi; Kato, Nobuo (1991). "Possible mechanisms underlying the slow lactose fermentation phenotype in Shigella spp". Applied and Environmental Microbiology. 57 (10): 2912–7. PMC 183896 Freely accessible. PMID 1746953.
  7. 1 2 3 4 Mani, Sachin; Wierzba, Thomas; Walker, Richard I. (2016). "Status of vaccine research and development for Shigella". Vaccine. 34 (26): 2887–2894. PMID 26979135. doi:10.1016/j.vaccine.2016.02.075.
  8. ↑ mayo clinic http://www.mayoclinic.org/diseases-conditions/shigella/basics/prevention/con-20028418
  9. ↑ "WHO vaccine pipeline tracker". World Health Organization. Retrieved 2016-07-29.
  10. ↑ "Vaccine Research And Development: New strategies for accelerating Shigella vaccine development" (PDF). Weekly Epidemiological Record. World Health Organization. 72 (11): 73–80. 14 March 1997. Retrieved 10 February 2012.
  11. 1 2 US Centers for Disease Control and Prevention. "Shigella – Shigellosis". Retrieved 2016-07-29.
  12. ↑ "How can Shigella infections be treated?". Shigellosis: General Information. Centers for Disease Control and Prevention.
  13. ↑ Christopher, Prince RH; David, Kirubah V; John, Sushil M; Sankarapandian, Venkatesan; Christopher, Prince RH (2010). "Antibiotic therapy for Shigella dysentery". The Cochrane Database of Systematic Reviews (8): CD006784. PMID 20687081. doi:10.1002/14651858.CD006784.pub4.
  14. ↑ "How can Shigella infections be treated?". Shigellosis: General Information. Centers for Disease Control and Prevention. Retrieved February 11, 2012.
  15. ↑ Katzung, Bertram G. (2007). Basic and Clinical Pharmacology. New York, NY: McGraw Hill Medical. p. 733. ISBN 978-0-07-145153-6.
  16. ↑ Ram, PK; Crump JA; Gupta SK; Miller MA; Mintz ED (2008). "Analysis of Data Gaps Pertaining to Shigella Infections in Low and Medium Human Development Index Countries, 1984–2005". Epidemiology and Infection. 136 (5): 577–603. PMC 2870860 Freely accessible. PMID 17686195. doi:10.1017/S0950268807009351.
  17. ↑ World Health Organization (2006). State of the art of new vaccine research and development (PDF).
  18. ↑ Angulo, Frederick J.; Swerdlow, David L. (1995). "Bacterial Enteric Infections in Persons Infected with Human Immunodeficiency Virus". Clinical Infectious Diseases. 21 (Supplement 1): S84–S93. doi:10.1093/clinids/21.supplement_1.s84.
  19. ↑ Todar, Kenneth. "Shigella and Shigellosis". Todar's Online Textbook of Bacteriology. Retrieved 10 February 2012.
  20. ↑ Baker, K et. al (September 2016). "Travel- and Community-Based Transmission of Multidrug-Resistant Shigella sonnei Lineage among International Orthodox Jewish Communities". Emerg Infect Dis. 22 (9): 1545–1553. doi:10.3201/eid2209.151953.
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