Cholera

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Causes

Cholera is an acute enteric infection caused by the ingestion of bacterium Vibrio cholerae present in faecally contaminated water or food. Primarily linked to insufficient access to safe water and proper sanitation, its impact can be even more dramatic in areas where basic environmental infrastructures are disrupted or have been destroyed. Countries facing complex emergencies are particularly vulnerable to cholera outbreaks. Massive displacement of IDPs or refugees to overcrowded settings, where the provision of potable water and sanitation is challenging, constitutes also a risk factor. In consequence, it is of paramount importance to be able to rely on accurate surveillance data to monitor the evolution of the outbreak and to put in place adequate intervention measures Coordination of the different sectors involved is essential, and WHO calls for the cooperation of all to limit the effect of cholera on populations.

Key messages

  • Cholera is transmitted through contaminated water or food. 

Symptoms

Cholera is characterized in its most severe form by a sudden onset of acute watery diarrhoea that can lead to death by severe dehydration. The extremely short incubation period – two hours to five days – enhances the potentially explosive pattern of outbreaks, as the number of cases can rise very quickly. About 75% of people infected with cholera do not develop any symptoms. However, the pathogens stay in their faeces for 7 to 14 days and are shed back into the environment, possibly infecting other individuals. Cholera is an extremely virulent disease that affects both children and adults. Unlike other diarrhoeal diseases, it can kill healthy adults within hours. Individuals with lower immunity, such as malnourished children or people living with HIV, are at greater risk of death if infected by cholera.

Key messages

  • Cholera can rapidly lead to severe dehydration and death if left untreated.
  • Prevention and preparedness of cholera require a coordinated multidisciplinary approach.

Diagnosis

The presence of V. cholerae in stools is confirmed through laboratory procedures. However, a new rapid diagnostic test (RDT), now available, allows quick testing at the patient’s bedside. WHO is currently in the process of validating this RDT, to be able to include it on the list of its pre-qualified products.

In the meantime, WHO suggests that all samples tested positive with the RDT are re-tested using classic laboratory procedures for confirmation. Not all cases fitting the WHO clinical case definition need to be tested. Once an outbreak is confirmed, a clinical diagnosis using WHO standard case definition is sufficient1, accompanied by sporadic testing at regular intervals.

Key messages

  • Once Vibrio choleraehas been confirmed, the WHO clinical case definition is sufficient to diagnose cases. After that laboratory testing is required for antimicrobial sensitivity testing and for confirming the end of an outbreak.
  • Rapid diagnostic tests can facilitated early warning and detection of first cases.

Treatment

Oral rehydration salts (ORS)

Efficient treatment resides in prompt rehydration through the administration of ORS or intravenous fluids, depending of the severity of cases. Up to 80% of patients can be treated adequately through the administration of ORS (WHO/UNICEF ORS standard sachet).Use of antibiotics

Rapid and appropriate rehydration is the main management intervention for treating cholera cases, either orally for moderate cases, or intravenously for severe cases

Appropriate antibiotics can reduce the volume of diarrhoea due to cholera, reduce the volume of rehydration fluids needed, and shorten the duration of V. cholerae excretion. The current WHO recommendation is to give antibiotics only to cholera cases with severe dehydration.

Careful and regular laboratory monitoring of the antibiotic sensitivity of circulating strains is recommended in all settings, including during an outbreak, to guide treatment. 

Prevention and control

In 2011, the World Health Assembly adopted resolution WHA 64.15 Cholera: mechanism for control and prevention, recognizing the re-emergence of cholera as a significant public health burden and threat.

Prevention

  • Provision of safe water, proper sanitation, and food safety are critical for preventing occurrence of cholera.
  • Health education aims at communities adopting preventive behaviour for averting contamination.

Control

The main tools for cholera control are:

  • proper and timely case management in cholera treatment centres;
  • specific training for proper case management, including avoidance of nosocomial infections;
  • sufficient pre-positioned medical supplies for case management (e.g. diarrhoeal disease kits);
  • improved access to water, effective sanitation, proper waste management and vector control;
  • enhanced hygiene and food safety practices;
  • improved communication and public information.

Outbreak response

WHO is currently responding to major cholera outbreaks around the world, particularly in the Democratic Republic of the Congo, Haiti, the Horn of Africa, Mozambique, South Sudan and Yemen.

WHO adapts its response to the local context, but the core response is to work with Ministries of Health , local partners and international networks such as GOARN to provide medical supplies, including oral rehydration solutions, IV fluids, cholera kits as well as rolling out OCV campaigns. WHO support strengthening of disease surveillance and investigation through the deployment of rapid response teams, training community health workers to conduct house-to-house case identification, and referral to cholera treatment centres. Much of this is supported by community mobilization and engagement. While the creation of an oral cholera vaccine stockpile has contributed significantly to cholera control, the preventive effect of vaccination is greatest when combined with improvements in water and sanitation, and WHO strongly advocates for combined interventions.

Source: http://www.who.int/cholera/en/

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Disclaimer: The above information has been taken from WHO website. Medlife is permitted to re-share WHO content in official blog and website.

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