1. Notification of cholera cases

1. Cholera is an endemic in India and several outbreaks of the disease have been reported. Because cholera has the potential of rapid spread leading to an acute public health problem, special attention is required to be given to the surveillance and prompt follow up action on reported cases of cholera.

2. A suspect case of cholera must be notified immediately by messenger, telephone or fax to the local health office. Weekly notification of confirmed cholera cases is required to be made by the state health authorities to the Directorate General of Health Services (Director, Central Bureau of Health Intelligence, Pushp Bhavan, Madangir Road, New Delhi - 110062) and endorsed to Director, National Institute of Communicable Diseases, 22 Shamnath Marg, Delhi -110054, (Phone:- 3971272, 3971060, 3913148; FAX: 3922677; Telegram: COMDIS, DELHI). The age, sex and address of the patient should be included.

3. If appropriate measures are taken, cholera remains restricted to a limited habitation. Therefore, reporting of taluka and district help in identifying the affected area.

4. The first suspect case of cholera in the area must be notified immediately to the local health officer. Laboratory confirmation should be obtained at the earliest opportunity and the results intimated to local health office as soon as these become available.

1. Clinical case description

• In an area where cholera is not endemic :

  Severe dehydration or death from acute watery

  diarrhoea in a patient aged 5 years or more

  or

• In an area where cholera is endemic:

  Acute watery diarrhoea, with or without

  vomiting in a patient aged 5 years or more

Case classification

Suspect : A case that meets the clinical case description.

Probable : Not applicable

Confirmed : A suspected case that is laboratory - confirmed

2. The symptoms of mild cases of cholera are clinically indistinguishable from non-specific acute diarrhoea. In more than 90% of the cases, cholera is mild.

3. It would also be useful to know if:

• there are any other laboratory confirmed cases in area

  OR

• there is a clustering of cases clinically compatible with cholera

Any one of the two above will support the presumptive diagnosis of cholera. It would also facilitate better understanding of the epidemiology of disease and institution of appropriate control measures.

1. There are more than 60 serogroups of Vibrio cholerae, but only serogroup O1 and 0139 cause cholera.

2. V.cholerae O1 occurs as two biotypes - classical and El Tor. Each biotype also occurs as two serotypes - Ogawa and Inaba.

3. Almost all the recent cholera outbreaks have been caused by the El Tor biotype. Cases caused by the classical biotype have not been reported in India since 1980. The El Tor biotype also causes a higher proportion of asymptomatic infections than the classical biotype and survives longer in the environment.

4. In late 1992, large-scale epidemics occurred in India and Bangladesh caused by a new serogroup - V.cholerae O139.

1. Man is the only host. Patients remain infectious usually for a few days after recovery from clinical symptoms. Occasionally the carrier stage may persist for several months. Antibiotics, to which the strain is susceptible, shorten the period of communicability.

2. V.cholerae can survive for long periods in the environment and can live in association with certain aquatic plants and animals, making water an important reservoir for infection.

1. Infection usually spreads through contaminated water and food.

2. The dose of V.cholerae required to produce illness depends on the susceptibility of the individual. It can be affected by the level of acidity in the stomach (the vibrio is destroyed at pH 4.5 or lower) and by immunity produced by prior infection. In endemic areas, breast-feeding protects infants and young children.

1. Incubation period varies from a few hours to 5 days, usually 2-3 days.

1. Early treatment, in most cases by Oral Rehydration Therapy (ORT), can reduce the case fatality of cholera to less than 1%. If treatment is delayed or inadequate, death from dehydration and circulatory collapse may follow rapidly.

2. Rapid loss of fluids and salts can result in dehydration, acidosis and potassium depletion if symptoms of diarrhoea and vomiting persist. Rehydration therapy should continue to replace ongoing loss of fluids and salts. The clinical condition of the patient should be monitored during and after rehydration until diarrhoea stops. Young and malnourished children need special attention.

Note:-To be used in one litre of potable water.

• Unsuitable ORS:

. ORS with high glucose content
. ORS with saccharine and colouring agents

Correct method of preparation of ORS at home is as follows:

3. Nearly 80 to 90% of the patients can usually be adequately treated with oral rehydration salt (ORS) solution alone, without intravenous therapy and antibiotics.

4. In severely dehydrated patients ORS solution should be started as soon as the patients are able to drink, even before the initial Intravenous (I V) fluid therapy has been completed.

Intravenous (I V) Fluid Therapy:

5. Intravenous therapy may be required for those with clinically severe form of cholera. IV fluids should be used only for the initial rehydration of patients with severe dehydration, including those who are in shock. Ringer's lactate solution is the preferred fluid for intravenous rehydration. Normal saline solution is less effective for intravenous rehydration, but can be used if Ringer's lactate solution is unavailable. Plain glucose solutions are ineffective and should not be used.

6. Patients on intravenous fluid therapy should be monitored at regular intervals to check for signs of improvement in the clinical condition of the patient. Care must be taken to ensure that the patient is not overloaded.

7. In severe cases, antibiotics can reduce the volume and duration of diarrhoea and can shorten the period during which the cholera vibrios are excreted. Antibiotics can be given orally as soon as vomiting stops, usually within 3-4 hours of starting rehydration. There is no advantage in giving injectable antibiotics which are expensive.

8. Use of antibiotics for mild cases is not recommended. This will hasten the development of antibiotic resistant strains as well as exhaust supply which may be needed for severe cases.

9. The choice of antibiotics should take into account local patterns of resistance to antibiotics. Knowledge of antibiotic sensitivity patterns in the immediate or adjacent areas is important. Studies conducted at NICD, Delhi; National Institute of Cholera and other Enteric Diseases (NICED), Calcutta and King Institute of Preventive Medicine, Chennai have shown that Vibrio cholerae that are currently prevalent are resistant to furazolidone, cotrimoxazole, ampicillin, nalidixic acid and streptomycin. These continue to be sensitive to tetracycline and norfloxacin.

   No anti diarrhoeal, anti-emetic, antispasmodic, cardiotonic or corticosteroid drugs should be used to treat cholera. Blood transfusion and volume expanders are not necessary. - Guidelines for Cholera Control, WHO 1993

10. Patients should be encouraged to take food, after severe vomiting has stopped, usually within 3 to 4 hours after starting rehydration. Breast-feeding of infants and young children should be continued.

1. Recognition of early warning signals, timely investigations and the application of specific control measures can limit the spread of an outbreak and prevent deaths. Control measures are most effective when selective interventions are applied early.

2. When an increase in the number of cases of diarrhoeal diseases is reported, the areas from where the cases are reported should be checked. Diagnosis should be confirmed of as many cases as possible to check that it is clinically compatible with cholera.

3. Line listing of cases, including age, sex and address should be made. Active search should be made for more cases.

4. Stool samples from a few typical cases may be collected and sent for laboratory examination.

5. Identify sources of drinking water. Check water quality for bacteriological contamination. If piped water supply, check for possible leakage. If a common source of water supply has been identified, inform public not to use the water for drinking purposes or for washing utensils etc.

6. Arrange alternate source for water, including tankers if possible. Chlorinate water source. Distribute chlorine tablets for domestic chlorination of water along with instructions for its proper use (Annex 4). Contact concerned authorities for safe water supply.

7. Alert health facilities and hospitals in the area. Make sure that adequate supplies of ORS, IV fluids, appropriate antibiotics and other essential supplies are available.

8. Arrange health educational activities in the community regarding personal and domestic hygiene, recommended sources of safe water supply, oral rehydration therapy and health facilities where patients can be taken for treatment.

9. Active case reporting should be continued for at least one week (preferably two weeks) after the occurrence of last case.

10. On confirmation of a focal outbreak of cholera, take precautionary measures as indicated in para 11 in other potentially high risk pockets in the district.

11. Notify immediately to the concerned state officer as soon as a clinically compatible case of cholera is reported.

12. The detailed procedures for conducting outbreak investigation, data analysis and report writing are given in a separate document (Outbreak Investigations - A Field Guide). A suggested format for report writing may be seen at Annex 6.

1. Health education and public awareness and co-operation are important to control an outbreak. If the community knows how the outbreak spreads and what measures they can take in their own families, the risks can be considerably reduced. It is also important that the public should know that treatment is simple and effective and there should be no cause for panic. ORS packets should be widely accessible. While the key messages will essentially remain the same for all areas, the language and style may be adapted to local needs.

   The Guidelines for Cholera Control, WHO 1993 have suggested several messages. Some of these are given below:

2. It is particularly important to inform the public that most cases of cholera can be treated with simple measures and that vaccination is not effective.

1. Treatment of cholera does not depend on the results of laboratory examination. However, laboratory examination of specimens from the first few suspected cases is important to confirm diagnosis and to determine the characteristics of the organism.

2. A sufficient number of stool specimens should be examined to identify the causative organism and test its sensitivity to antibiotics. Once the presence of cholera is confirmed, it is not necessary to examine specimens from all cases or contacts. In fact, this should be discouraged since it places an unnecessary burden on laboratory facilities and is not required for effective treatment.

3. Stool specimens or rectal swabs should be sent to the laboratory in a transport medium (e.g. Cary-Blair medium, VR medium, Alkaline Peptone Water). If a transport medium is not available, cotton tipped rectal swab soaked in the liquid stool should be placed in a sterile plastic bag and tightly sealed. Specimens should be collected before the patient has received any antibiotics.

4. Full particulars of the patient(s) from whom samples have been collected must be sent along with the samples as many factors can influence the results of the laboratory tests. The information that should accompany each stool sample is given below:

•   Name, Age, Sex

•   Name of mother or father

•   Address

•   Date of onset of symptoms

•   Provisional diagnosis

•   Clinical outcome (recovered, under treatment, dead, not known)

•   Antibiotic received prior to collection of sample - Y/N/not known

•   Date sample collected

5. Apart from prior treatment with antimicrobials, the conditions of collection and transportation of samples can influence laboratory tests. The recommended practices and precautions to be taken to minimise deterioration in the quality of the sample are given in the box.

6. Keep an inventory of all laboratories in the district which can undertake culture and identification of V.cholerae 01. The names of these laboratories should be known to the medical officers of the peripheral health facilities. Each laboratory must be well stocked with the media and other reagents. The available stocks should be verified well before the expected seasonal increase of cases of diarrhoeal diseases.

7. Districts considered at high risk where outbreaks have been reported in the past, orientation session of the paramedical personnel, laboratory technicians and medical officers is recommended for updating their knowledge and skills in the correct procedures for collection, storage and transportation of laboratory samples.

8. The states could also identify a reference laboratory to perform antibiotic sensitivity tests.

9. More complicated procedures such as phage typing and toxin testing are undertaken by the national reference laboratory at the National Institute of Cholera and other Enteric Diseases (NICED), P-33, CIT Road, Scheme XM, Beliaghata, Calcutta - 700 010, Phone:-3504598, 3505533, 3504478, 3500448 FAX:-3505066.

1. The risk of an outbreak of cholera and its spread can be minimised by taking measures given below. There are no other alternatives for the control of an outbreak of cholera.

•   provision of safe water

•   adopting safe practices in food handling

•   sanitary disposal of human waste

•   personal and domestic hygienic practices

2. The above steps are required both as long-term measures to prevent cholera as well as measures to be taken in a focal area where an outbreak is anticipated. Community participation is essential to prevent an outbreak so that safe practices are followed for storing water and for food handling.

3. When an outbreak occurs or when the risk of such outbreaks is high, the co-operation of other government departments, non-governmental agencies and the community often becomes necessary. Such help will be more forthcoming if mechanisms for interaction have been developed before the onset of an outbreak. It might be useful to convene a meeting of the concerned departments, community representatives and the NGOs before the expected seasonal increase of cases of diarrhoeal diseases. Some mechanism for briefing the press should also be established. Some suggested areas in which the government departments and NGOs can assist, is placed at Annex 5.

4. According to WHO guidelines, chemoprophylaxis, vaccination and travel & trade restrictions have been found to be ineffective and are not recommended for the control of an outbreak of cholera or for the prevention of its spread to other areas.

5. Mass chemoprophylaxis is not only ineffective in preventing the spread of cholera, but it also diverts manpower and resources from effective measures. In several countries, it has contributed to the emergence of antibiotic resistance in the vibrio, depriving severely ill patients from valuable treatment. The value of selective chemotherapy of household contacts is also doubtful. It is not recommended as a routine measure.

6. Vaccines that are currently available do not have high vaccine efficacy rates. 2 doses are required for primary immunization. In those who are immunised, protection lasts for 3-6 months only. Vaccination does not reduce the incidence of asymptomatic infections or prevent the spread of infection. Inadequately sterilised needles and syringes may transmit the parentally transmitted infections such as HIV and Hepatitis B. Vaccination campaigns divert resources and manpower from more useful control activities. Therefore, cholera vaccination is an ineffective measure. At present, no country requires travellers to have a cholera vaccination certificate.

7. Travel and trade restrictions between countries or different areas within a country do not prevent the spread of cholera. Majority of the infected individuals have no symptoms. Setting up check-posts requires massive inputs and diverts attention from other more useful control measures.

1. Alert health personnel and hospitals to report increase or clustering of cases of diarrhoea. If a case of dehydration following diarrhoea is seen in children 5 years or older, cholera should be suspected and notified to the local health office immediately. All health facilities including those having only OPD should maintain records of patients seen. Address of the patients should be recorded and maintained locally for use in case an outbreak occurs. If there is a sudden increase in cases or clustering of cases in an area, field investigations should be carried out and necessary corrective action taken. An effective surveillance system can provide an early warning signal and help in initiating appropriate actions to quickly contain outbreaks of all waterborne diseases, including cholera.

   Particular attention may be given in the pre-monsoon period before the expected seasonal increase of water-borne diseases; however, these measures are expected to be in place round the year.

2. Ensure that the health personnel are adequately trained in oral rehydration therapy and that the recommended guidelines are followed in the hospitals. If necessary, orientation sessions or retraining may be organised. Early treatment can save many lives.

3. Arrange random checks for water quality for coliform organisms (faecal contamination). Special attention may be given to high risk pockets. In places where water is found to be of unsatisfactory quality, follow-up action may be taken with the concerned authorities for water supply. Chlorination should be carried out to render water safe for drinking (Annex 3).

4. Health educational activities should be carried out in the community to promote safe practices especially before the monsoons when the seasonal increase of cases of diarrhoeal diseases can be expected.

5. Check that adequate stocks of essential supplies are available and have been distributed to the peripheral health institutions well in advance of the expected seasonal increase of cases of diarrhoeal diseases. ORS packets should be available in all the health facilities. It is recommended that adequate stocks of bleaching powder, chlorine tablets, IV fluids and appropriate antibiotics are in stock in case of an emergency.

6. A nodal officer should be identified at the state and district levels with the responsibility of collecting and analysing relevant surveillance reports and for ensuring that appropriate follow-up action as required is taken up promptly. The name of the nodal officer should be made widely known so that she/he could be contacted in case of an emergency or if clarifications or additional information is required by the medical and health personnel in the periphery.