TM7b Vaccination programmes and campaigns in emergencies. Vaccination programmes and campaigns in emergencies

Transcription

1 TM7b Vaccination programmes and campaigns in emergencies General Objective Outline the principles of vaccination programs and the delivery of campaigns in emergency situations. Specific Objectives At the end of the session, participants will be familiar with: Principles of vaccination programs Vaccination campaigns in emergency situations Content Vaccination programmes Vaccination campaigns delivery models in emergency situations: Measles Meningococcal meningitis 1

2 Immunization against diseases of public health importance 1 The benefits of immunization Vaccines which protect against disease by inducing immunity are widely and routinely administered around the world based on the commonsense principle that it is better to keep people from falling ill than to treat them once they are ill. Suffering, disability, and death are avoided. Immunization averted about two million deaths in In addition, contagion is reduced, strain on health-care systems is eased, and money is frequently saved that can be used for other health services. Immunization is a proven tool for controlling and even eradicating disease. An immunization campaign carried out by the World Health Organization (WHO) from 1967 to 1977 eradicated the natural occurrence of smallpox. When the programme began, the disease still threatened 60% of the world's population and killed every fourth victim. Eradication of poliomyelitis is within reach. Since the launch by WHO and its partners of the Global Polio Eradication Initiative in 1988, infections have fallen by 99%, and some five million people have escaped paralysis. Between 1999 and 2003, measles deaths dropped worldwide by almost 40%, and some regions have set a target of eliminating the disease. Maternal and neonatal tetanus will soon be eliminated in 14 of 57 high-risk countries. New vaccines also have been introduced with significant results, including the first vaccine to help prevent liver cancer, hepatitis B vaccine, which is now routinely given to infants in 77% of WHO's Member States. Rapid progress in the development of new vaccines means protection will be available in the near future against a wider range of serious infectious diseases. History Introducing a small amount of smallpox virus by inhaling through the nose or by making a number of small pricks through the skin (variolation) to create resistance to the disease appears to have begun in the 10th or 11th century in Central Asia. The practice spread; in Asia and Africa, the method was nasal, while in Europe it involved skin punctures. Variolation was introduced into England in There, in 1798, Edward Jenner, having studied the success of variolation with cowpox a mild illness in protecting against smallpox, began to carry out inoculations against smallpox, the first systematic effort to control a disease through immunization. In 1885, Louis Pasteur developed the first vaccine to protect humans against rabies. Toxoids against diphtheria and tetanus were introduced in the early 1900s; the bacillus Calmette-Guérin vaccine (against tuberculosis) in 1927; the Salk polio vaccine in 1955; and vaccines against measles and mumps in the 1960s

3 Commonly used vaccines Routine vaccination is now provided in all developing countries against measles, polio, diphtheria, tetanus, pertussis, and tuberculosis. To this basic package of vaccines, which served as the standard for years, have come new additions. Immunization against hepatitis B is now recommended by WHO for all nations, and currently is offered to infants in 147 of 192 WHO Member States. Immunization against Haemophilus influenzae type b (Hib) is recommended where resources permit its use and the burden of disease is established; it is provided in 89 countries (only in selected parts of two of those countries). Yellow fever vaccine is offered in about two-thirds of the nations at risk for yellow fever outbreaks. Routine immunization against rubella is provided in 111 countries. In industrialized countries a wider span of protection is typically provided than in developing countries, often including vaccines against influenza, predominant strains of pneumococcal disease, and mumps (usually in combination with measles and rubella vaccine). Immunization programmes may be aimed at adolescents or adults depending on the disease concerned as well as at infants and children. Global immunization coverage Coverage has greatly increased since WHO's Expanded Programme on Immunization began in In 2003, global DTP3 (three doses of the diphtheria-tetanus-pertussis combination vaccine) coverage was 78% up from 20% in However, 27 million children worldwide were not reached by DTP3 in 2003, including 9.9 million in South Asia and 9.6 million in sub- Saharan Africa. Those who miss out on routine vaccination programmes tend to be people living in remote locations, urban slums and border areas. They also include indigenous groups, displaced populations, those lacking access to vaccination because of various social barriers, those lacking awareness or motivation to be vaccinated and those who refuse. An estimated 2.1 million people around the world died in 2002 of diseases preventable by widely used vaccines. This toll included 1.4 million children under the age of five. Among these childhood deaths, over were caused by measles; nearly by Hib; nearly by pertussis; and by neonatal tetanus. Vaccines under development Numerous new vaccines with major potential for improving health in developing countries are in the research and development pipeline. They include vaccines for rotavirus diarrhoea, which kills to children under age five every year; human papillomavirus, a leading cause of cervical cancer, which afflicts some women each year, 80% of them in developing countries; and pneumococcal disease, which causes a large fraction of the world's approximately two million annual deaths from childhood pneumonia. In addition, a conjugate vaccine now in development should be 3

4 much more effective against Group A meningococcal disease (Men A), a frequently fatal form of meningitis that causes recurring epidemics in a number of countries in sub-saharan Africa. Several of these vaccines those against rotavirus, pneumococcal disease, and Men A may be available in developing countries by How vaccines work Vaccines typically provide the immune system with harmless copies of an antigen: a portion of the surface of a bacterium or virus that the immune system recognizes as "foreign." (An antigen often plays a role in causing disease for example by enabling a virus or bacterium to attach to cells.) A vaccine may also provide a non-active version of a toxin a poison produced by a bacterium so that the body can devise a defence against it. Once an antigen is detected by the immune system, white blood cells called B-lymphocytes create a protein called an antibody that is precisely designed to attach to that antigen. Many copies of this antibody are produced. If a true infection of the same disease occurs, still more antibodies are created, and as they attach to their targets they may block the activity of the virus or bacterial strain directly, thus combating infection. In addition, once in place, the antibodies make it much easier for other components of the immune system (particularly phagocytes) to recognize and destroy the invading agent. Immune systems are designed to "remember" once exposed to a particular bacterium or virus, they retain immunity against it for years, decades, or even a lifetime and so are prepared to defeat a later infection, and to do so quickly. This ability, and the speed with which it occurs, is a huge benefit: a body encountering a germ for the first time may need from seven to 12 days to mount an effective defence, and by then serious illness and even death may occur. Types of vaccines Vaccines come in different forms. The injected polio vaccine is a killed, intact virus; the oral polio vaccine is a live, weakened virus. The vaccine for typhoid is a killed, intact bacteria. Vaccines for measles and the other standard "childhood" diseases mumps, chickenpox, and rubella are live, attenuated (or weakened) viruses. Vaccines for diphtheria and tetanus consist of toxins that have been "inactivated." Influenza vaccines often consist of killed, "disrupted" viruses (that is, the proteins on the coat of the virus have been released into a solution by solvents). Vaccines against Hib, pneumococcal disease, and meningococcal disease consist of highly purified complex sugars taken from bacterial coats or capsules. Vaccines are frequently administered as combinations of antigens. The most widely used combinations are diphtheria-tetanus-pertussis (DTP); diphtheria-tetanus-pertussis-hepatitis B (DTP-HepB); pentavalent vaccine: 4

5 diphtheria-tetanus-pertussis-hepatitis B-Hib; and measles-mumps-and rubella (MMR). Effectiveness and safety All vaccines used for routine immunization are very effective in preventing disease, although no vaccine attains 100% effectiveness. More than one dose of a vaccine is generally given to increase the chance of developing immunity. Vaccines are very safe, and side effects are minor especially when compared to the diseases they are designed to prevent. Serious complications occur rarely. For example, severe allergic reactions result at a rate of one for every doses of measles vaccine. Two to four cases of vaccine-associated paralytic polio have been reported for every one million children receiving oral polio vaccine. The cost-effectiveness of immunization Immunization is considered among the most cost-effective of health investments. There is a well-defined target group; contact with the health system is only needed at the time of delivery; and vaccination does not require any major change of lifestyle. A recent study estimated that a one-week "supplemental immunization activity" against measles carried out in Kenya in 2002 in which 12.8 million children were vaccinated would result in a net saving in health costs of US$ 12 million over the following ten years; during that time it would prevent cases of measles and deaths. In the United States, costbenefit analysis indicate that every dollar invested in a vaccine dose saves US$ 2 to US$ 27 in health expenses. The cost of immunizing a child In mid-1990s, vaccines to provide "basic" coverage for tuberculosis, polio, diphtheria, tetanus, pertussis, and measles cost about US$ 1 per child. Inclusion of vaccines for hepatitis B and Hib, raises the vaccine cost alone to US$ 7-13 per child (not including administration and injection equipment) in the developing world. When vaccine administration is included, the costs amount to between US$ per child. It has become a significant challenge for low-income countries and international health agencies to find ways to introduce more highly-priced vaccines such as those for hepatitis B and Hib, which can greatly increase the costs of national immunization programmes. With many new vaccines expected to be available in the near future, issues of financing and financial sustainability will become ever more important. 5

6 Financing immunization Many developing countries have difficulties affording vaccines. International initiatives such as the Expanded Programme on Immunization and the Global Alliance for Vaccines and Immunization (GAVI) have provided impetus, funding, and technical support that have helped increase immunization coverage and the number of vaccines provided. The proposed WHO-UNICEF Global Immunization Vision and Strategies, intended to run from , would further this existing coordination, aim to expand vaccination coverage, and enable the logistical systems set up for that purpose to provide other health care services as well. The economics of vaccine development have tended to run against the interests of the world's poorer countries. Vaccines are much less profitable than medicines, and pharmaceutical firms understandably have been reluctant to make the high investments necessary to research and develop vaccines against infectious diseases, realizing that the largest pool of potential customers are governments that likely could not afford to pay enough for these products to ensure a profit. For the same reason, when new vaccines have been developed, limited quantities often have been manufactured, increasing the cost per dose. Part of the difficulty for manufacturers is in forecasting demand and in accounting for various market uncertainties. Steps have been taken to deal with these challenges. The UNICEF Vaccine Independence Initiative, established in 1991, sets up a revolving fund for each participating country, allows these countries to buy vaccines through UNICEF's procurement system using local currencies, and enables them to pay for the vaccines only after delivery. A more recent approach is to guarantee a large market and a reasonable price in advance to pharmaceutical firms which develop vaccines that will have great health benefits for poor nations. This "push-pull" approach is being financed and progressively fine-tuned by a coalition of international donors, bilateral aid programmes, private philanthropists, and some governments. WHO immunization work In the field of immunization WHO works with partners including governments, United Nations agencies and other international organizations, bilateral government health and development agencies, non-governmental organizations, professional groups and the private sector. WHO's specific responsibilities include: Supporting and facilitating research and development; Ensuring the quality and safety of vaccines; Developing policies and strategies for maximizing the use of vaccines; Reducing financial and technical barriers to the introduction of vaccines and technologies; and Supporting countries in acquiring the skills and infrastructure needed to achieve disease control and eradication. 6

7 Vaccination campaigns delivery models in emergency situations Measles Measles remains a major cause of childhood mortality throughout the world, especially in developing countries. However, the disease can be prevented by vaccination. Measles immunization has been established since the 70s as part of the Expanded Programme on Immunization (EPI) and has significantly contributed to reducing child mortality. Despite a high level of global vaccination coverage in 1993 (78%, WHO reporting), there were an estimated 45 million cases and 1.2 million deaths through out the world. One reason could be the wide variation for vaccination coverage across regions: 19 countries, most of them in Africa, report vaccine coverage below 50%. Measles is one of the main contributors to child mortality and one of the most urgent health problems in refugee populations. Measles outbreaks are frequent, especially in camp settings as overcrowding is one of the most important risk factor for measles transmission. Complications such as pneumonia, diarrhoea and croup are very common and case fatality rates can reach very high figures, exceeding 10%. However, high mortality due to measles is preventable, and mass immunization against measles, coupled with vitamin A distribution, is one of the top priorities in the initial phase of a refugee influx, even if refugees are coming from areas with high vaccination coverage rates. The vaccine seems to offer good protection but not perfect as it protects 85% of children if administered at the age of 9 months. This means that there is still a significant number of people susceptible to measles and therefore vulnerable to outbreaks, given the extreme infectiousness of the virus. It is therefore essential to aim for a coverage near 100%. Objective The objective of a mass vaccination campaign is to prevent measles outbreaks and in this way to prevent avoidable deaths. To achieve this, it is essential to aim for % coverage in the age group from 6 months to 15 years. If the outbreak occurs before the mass vaccination campaign takes place, the objective is to prevent measles deaths as exposed individuals can experience less severe disease if vaccinated within 3 days of exposure. Target population The vaccine has to be administered when there is no longer risk of interfering with maternal antibodies in order to achieve optimal response. The recommended age of vaccination according to EPI (Expanded Programme of Immunization) in developing countries is from 9 months to 2-5 years. At 6 months vaccine efficacy drops from 85% (at 9 months) to 50%. In refugee settings, overcrowding and other factors, increase the risk of infection in young children and the severity of disease in all age groups. The target group has to be expanded: 6 months to 15 years in the emergency phase. In open situations, the same age group among the local population should also be 7

8 immunized. However, every child that has been vaccinated between 6 and 9 months of age, should receive a second dose after 9 months. Children up to years of age should be included, as they are susceptible and there is a shift to older groups recently. Measles related mortality and morbidity can be quite high in this group, too. If an outbreak occurs, and if age groups older than 15 years of age are affected, the target population can be expanded further. Measles vaccination is only contra-indicated in pregnant women because the vaccine contains a live attenuated virus. Malnutrition, HIV/AIDS, previous vaccination, infection are not contra-indications. A 2 nd dose given to children previously immunized provides an even better protection. Planning an immunization campaign The resources required to implement mass immunization should be available as soon as refugees begin to gather on sites. One agency should take overall responsibility for the programme and coordinate the various efforts involved. Responsibility for each component of the programme needs to be clearly assigned to the different partners involved (health agencies, Ministry of Health and local EPI representatives and refugee leaders). The national EPI of the host country should be involved from the beginning. Main tasks include: Estimation of the target population Obtain a map of the site Define the vaccination strategies Estimation of resources needed: staff, vaccines, equipment Procurement and management of resources Cold chain Mass immunization campaign One immunization team includes 20 people: 1 supervisor, 1 logistics officer, 4 staff preparing vaccines, 2 staff members administering the vaccines, 6 staff members to register and tally, 6 staff members to maintain order (crowd control). Such a team can immunize people/hour. Main aspects of organization are: Training session 2-3 days before the campaign Dissemination of information among the target population Selection and preparation of immunization sites (1 or 2 sites for every 10,000 refugees) Issue of individual cards for each child Daily record of the numbers vaccinated per day Fixed immunization sites should be integrated to existing health structures if available. Evaluation is an integral part of the whole effort. Routinely collected data, vaccination coverage survey and a study for vaccine efficacy (if failures are suspected) are various methods to be used. Routinely collected data must 8

9 always be evaluated, but vaccination coverage survey and a study for vaccine efficacy do not have to be undertaken systematically after each campaign, unless the accuracy of results is under question. Meningococcal meningitis Meningitis is an infection of the meninges, the thin lining that surrounds the brain and the spinal cord. Several different bacteria can cause meningitis and Neisseria meningitidis is one of the most important because of its potential to cause epidemics. Meningococcal disease was first described in 1805 when an outbreak swept through Geneva, Switzerland. The causative agent, Neisseria meningitidis (the meningococcus), was identified in 1887 Large outbreaks of meningitis are exclusively due to meningococcus (Neisseria meningitides). More than 13 serogroups of meningococcus have been isolated and differ in epidemic potential. Only serogroups A, B and C can cause outbreaks. The serogroups are divided into serotypes, sub-types and clones. 90% of outbreaks are due to serogroup A. Serogroup B (in Europe and South America) generally causes only sporadic cases or small outbreaks. Serogroup C has been responsible for a few outbreaks in Africa, Asia and South America. Haemophilus influenza and Streptococcus pneumoniae are other frequent causes of sporadic meningitis cases and other etiologic agents can also be found. Traditionally, most meningitis outbreaks occurred in the region described as the meningitis belt in sub-saharan Africa. Outbreaks used to occur every 8 to 12 years and stopped at the onset of the rainy season. However, epidemiological patterns have changed since the 80s and outbreaks increasingly occur in African countries located outside the meningitis belt. This change may be due to the arrival of a new clone (Neisseria meningitis serogroup A clone III-1), climate changes or increased mobility of the populations, including refugee movements. It is now reported that epidemics occur at any time of the year and in any region. There is increasing evidence of serogroup W135 being associated with outbreaks of considerable size. In 2000 and 2001 several hundred pilgrims attending the Hajj in Saudia Arabia were infected with N. meningitidis W135. Then in 2002, W135 emerged in Burkina Faso, striking 13,000 people and killing 1,500. The African meningitis belt The highest burden of meningococcal disease occurs in sub-saharan Africa, which is known as the Meningitis Belt, an area that stretches from Senegal in the west to Ethiopia in the east, with an estimated total population of 300 million people. This hyperendemic area is characterized by particular climate and social habits. During the dry season, between December and June, because of dust winds and upper respiratory tract infections due to cold nights, the local immunity of the pharynx is diminished increasing the risk of meningitis. At the same time, the transmission of N. meningitidis is favoured by overcrowded housing at family level and by large population displacements due to pilgrimages and traditional markets at regional level. This conjunction of factors explains the large epidemics which occur during this season in the meningitis belt area. Due to herd immunity (whereby transmission is blocked 9

10 when a critical percentage of the population had been vaccinated, thus extending protection to the unvaccinated), these epidemics occur in a cyclic mode. N. meningitidis A, C and W135 are now the main serogroups involved in the meningococcal meningitis activity in Africa. In major African epidemics, attack rates ranges from 100 to 800 per population, but individual communities have reported rates as high as 1000 per While in endemic disease the highest attack rates are observed in young children, during epidemics, older children, teenagers and young adults are also affected. In 1996, Africa experienced the largest recorded outbreak of epidemic meningitis in history, with over cases and deaths registered. Between that crisis and 2002, 223,000 new cases of meningococcal meningitis were reported to the World Health Organization. The countries most affected countries have been Burkina Faso, Chad, Ethiopia and Niger; in 2002, the outbreaks occurring in Burkina Faso, Ethiopia and Niger accounted for about 65% of the total cases reported in the African continent. Furthermore, the meningitis belt appears to be extending further south. In 2002, the Great Lakes region was affected by outbreaks in villages and refugees camps which caused more than 2,200 cases, including 200 deaths. The population at risk is classically the age group below 30, in which 80% of cases occur. Nevertheless, during epidemics in the 90, clone Neisseria meningitis serogroup A clone III-1, high attack rates and case fatality rates were reported in those of over 30 years (Uganda and Burundi, 1992). The overall attack rate ranges from 10 to 1,000 per 100,000 and varies widely. Variability may exist from one epidemiological week to another: a range from cases per 100,000 have been reported. The CFR (case fatality rate), without treatment can reach 70%. With treatment varies from 5-15%. Outbreaks usually last weeks, but can vary from 4 to 20 weeks. The peak is normally reached 4 weeks after the onset (range:2-8 weeks). How is the disease transmitted The bacteria are transmitted from person to person through droplets of respiratory or throat secretions. Close and prolonged contact (e.g. kissing, sneezing and coughing on someone, living in close quarters or dormitories (military recruits, students), sharing eating or drinking utensils, etc.) facilitate the spread of the disease. The average incubation period is 4 days, ranging between 2 and 10 days. N. meningitidis only infects humans; there is no animal reservoir. The bacteria can be carried in the pharynx and sometimes, for reasons not fully known, overwhelm the body s defences allowing infection to spread through the bloodstream and to the brain. It is estimated that between 10 to 25% of the population carry N.meningitidis at any given time, but of course the carriage rate may be much higher in epidemic situations. The disease 10

11 The most common symptoms are stiff neck, high fever, sensitivity to light, confusion, headaches and vomiting. Even when the disease is diagnosed early and adequate therapy instituted, 5% to 10% of patients die, typically within hours of onset of symptoms. Bacterial meningitis may result in brain damage, hearing loss, or learning disability in 10 to 20% of survivors. A less common but more severe (often fatal) form of meningococcal disease is meningococcal septicaemia which is characterized by a haemorrhagic rash and rapid circulatory collapse. Diagnosis The diagnosis of meningococcal meningitis is suspected by the clinical presentation and a lumbar puncture showing a purulent spinal fluid; sometimes the bacteria can be seen in microscopic examinations of the spinal fluid. The diagnosis is confirmed by growing the bacteria from specimens of spinal fluid or blood. More specialised laboratory tests are needed for the identification of the serogroups as well as for testing susceptibility to antibiotics. Treatment Meningococcal disease is potentially fatal and should always be viewed as a medical emergency. Admission to a hospital or health centre is necessary. Isolation of the patient is not necessary. Antimicrobial therapy must be commenced as soon as possible after the lumbar puncture has been carried out (if started before, it may be difficult to grow the bacteria from the spinal fluid and thus confirm the diagnosis). A range of antibiotics may be used for treatment including penicillin, ampicillin, chloramphenicol, and ceftriaxone. Under epidemic conditions in Africa, oily chloramphenicol is the drug of choice in areas with limited health facilities because a single dose of this long-acting formulation has been shown to be effective. Prevention Several vaccines are available to prevent the disease. Polysaccharide vaccines, which have been available for over 30 years, exist against serogroups A, C, Y, W135 in various combinations. A monovalent conjugate vaccine against serogroup C, has recently been licensed in developed countries for use in children and adolescents. This vaccine is immunogenic, particularly for children under 2 years of age whereas polysaccharide vaccines are not. All these vaccines have been proven to be safe and effective with infrequent and mild side effects. The vaccines may not provide adequate protection for 10 to 14 days following injection. Vaccination use Routine vaccination: Routine preventive mass vaccination has been attempted and its effect has been extensively debated. Saudi Arabia, for 11

12 example, offers routine immunization of its entire population. Sudan and other countries routinely vaccinate school children. Preventive vaccination can be used to protect individuals at risk (e.g. travellers, military, pilgrims). Protection of close contacts: When a sporadic case occurs, the close contacts need to be protected by a vaccine and chemoprophylaxis with antibiotics to cover the delay between vaccination and protection (see above). Antibiotics used for chemoprophylaxis are rifampicin, minocycline, spiramycin, ciprofloxacin and ceftriaxone. Vaccination for epidemic control: In the African Meningitis Belt context, enhanced epidemiological surveillance and prompt case management with oily chloramphenicol are used to control the epidemics. Routine immunization is not possible with the current available vaccines as the polysaccharide vaccines provide protection for only three to five years and cannot be used in children under 2 years of age because they lack the ability to develop antibodies. Furthermore, even large scale coverage with current vaccines does not provide sufficient herd immunity. Consequently, the current WHO recommendation for outbreak control is to mass vaccinate every district that is in an epidemic phase, as well as those contiguous districts that are in alert phase. It is estimated that a mass immunization campaign, promptly implemented, can avoid 70 % of cases. Emergence of W135: Bivalent AC vaccine is commonly used in Africa but the emergence of N. meningitidis W135 as an epidemic strain involves revising this control strategy. A tetravalent ACYW135 polysaccharide vaccine exists but its high price and limited availability restricts its use in the African context. In 2003, WHO reached an agreement with a manufacturer to produce an affordable polysaccharide vaccine for Africa which would protect against A, C and W135 strains. WHO s strategy WHO promotes a two-pronged strategy which involves epidemic preparedness and epidemic response. Preparedness focuses on surveillance, from case detection and investigation and laboratory confirmation. This implies strengthening of surveillance and laboratory capacity for early detection of epidemics, the establishment of national and sub-regional stocks of vaccine, and the development or updating of national plans for epidemic management (including preparedness, contingency and response). WHO regularly provides technical support in the field, in the countries facing epidemics. Following large outbreaks in Africa in , WHO was instrumental in establishing the International Coordinating Group (ICG) on Vaccine Provision for Epidemic Meningitis Control to ensure rapid and equal access to vaccines, injection material and oily chloramphenicol, as well as for their adequate use when the stocks are limited. The ICG is composed of partners from the UN, including WHO, nongovernmental organizations, technical partners and the private sector. WHO is committed to eliminating 12

13 meningococcal disease as a public health problem and ensuring control of sporadic cases through routine health services in the shortest possible time. The only way to reach this goal will be with an improved vaccine. WHO supports the development of such a vaccine. Surveillance Meningitis surveillance should always be part of the routine surveillance system to detect any outbreak and initiate control measures at the earliest possible stage. There should be a standard case definition. Lumbar puncture is necessary to confirm the diagnosis, and identify the meningococcus in the first suspected cases. It must be remembered that clinical diagnosis does not differentiate serogroup A meningococcal meningitis from other causes of sporadic meningitis. Suspected case: <12 months with fever and bulging fontanel >12 months and adults with sudden onset of fever with stiff neck and/or petechial or purpular rash Probable case: Suspected case with turbid CSF (with or without Gram stain) Suspected case with ongoing outbreak Confirmed case: Suspected or probable case and CSF antigen detection (positive latex agglutination test) Suspected or probable case with positive culture The number of cases should be followed closely, and the data to be collected for each patient should include full demographic data, onset, type of diagnosis (clinical, CSF etc), treatment, outcome, immunization status and date of immunization. The number of case per week per 100,000 refugees should be computed and compared with epidemic threshold and age of cases is needed in order to define target groups for vaccination campaign. Outbreak identification and control In an outbreak prioritization has to be given to the determination of the aetiology and serogroup, since establishing the presence of serogroup A or C is crucial for planning further steps. Laboratory investigation should always be performed on the first suspected cases and may be done using a rapid test (latex agglutination test CSF), that should be available in all refugee settings. Confirmation by culture is difficult to attain in the field the meningococcus is fragile but could be essential for antibiotic resistance patterns. It is not possible to define a universal epidemic threshold due to variations in incidence rates due to climate, season or geography. Thresholds 13

14 should be defined for each specific setting. In a large refugee population (over 30,000) it is generally recommended to use a threshold of 15 cases/100,000/persons/week during 2 consecutive weeks. In smaller populations it can be as low as 2-3 cases per week. In very large populations the general threshold of 15 cases/100,000/persons/week may be unsuitable due to very low attack rates that could obscure higher attack rates within subgroups of the overall population. Once an epidemic is confirmed, mass immunization and treatment must be rapidly and effectively organized to prevent cases, deaths and reduce CFR. Mass immunization campaign A mass immunization campaign can be effective in controlling outbreaks of meningococcus A and C, but it will only have an impact if implemented early on. It should implemented within the first 4-8 weeks. However, recent data, suggest that this delay might be too long to allow time for protective levels of antibodies. Mass vaccination is not recommended if it is definitely too late and the epidemic curve is clearly decreasing. The appropriateness of a mass vaccination campaign during an emergency phase with high mortality rates or scarce resources should always be questioned and weighed against the alternative strategy of focusing on early case detection and treatment. If an epidemic due to a classic clone (other than the III-1) in the meningitis belt occurs in proximity to the rainy season, might also lead to a decision not to undertake a mass immunization campaign. Immunization should not be limited to the refugee population but should cover the whole area affected, as well the surrounding ones. The same holds of course for open situations with refugees living among the local communities. Target groups should be decided based on age specific attack rates, but it is preferable to consider mass vaccination of the entire population above 6 months. If resources and time are limited, prioritization should be given to the age group 6 months to 30 years of age. Good organization is crucial for a successful campaign. Teams of 20 members can vaccinate people/hour. Immunization starts from the center of the outbreak and includes all contacts spreading out in near locations. Surveillance during an outbreak After confirming an outbreak, surveillance should increase to detect new cases using a case definition on clinical grounds (preferably with visual CSF detection. Weekly compilation of cases allows the drawing of an epidemic curve. Collecting information on vaccination status of cases, allows evaluation of vaccine efficacy to take place. Simplified treatment protocol for bacterial meningitis 14

15 Meningitis is an emergency: the earlier the treatment, the better the chances of a cure. Clinical features Children more than one year old and adults: sudden fever > 38.5 C, stiffness of the neck, headaches, vomiting Children less than one year old: fever > 38.5 C, hypotonia, dehydration and bulging fontanelle Treatment ANTIBOTIC TREATMENT Children more than one year old and adults oily chloramphenicol IM Children: 100 mg/kg Adults: 3 g (6 vials of 500 mg) Age months 2-5 years 6-9 years years > 14 years Dose 1 g 1.5 g 2 g 2.5 g 3 g Volume 4 ml 6 ml 8 ml 10 ml 12 ml This single dose should be administered in 2 injections one in each buttock as the product is viscous. Pregnant and lactating women The use of ceftriaxone or ampicillin is preferred, if available; if not available, oily chloramphenicol can be used, as the priority is to administer treatment quickly. Children between 2 months and one year old ceftriaxone IM: 80 mg/kg once daily (i.e. about 250 mg/day) for 5 days IV solvent can be used by IM route, but never use IM solvent by IV route as it contains lidocaine. 15

16 If ceftriaxone is not available, oily chloramphenicol can be used. Children under 2 months of age ampicillin slow IV: 200 mg/kg/day in 3 divided doses for 5 days Use IV route for 5 days before changing to the IM route (same dosage) or oral route with amoxicillin PO: 100 mg/kg/day) for a further 3 to 5 days. Treatment of fever Either bathe the child or keep him/her damp with a cloth. Administer paracetamol PO: Age 0 2 months 1 year 5 years 15 years Adult Weight 0 4 kg 8 kg 15 kg 35 kg 100-mg tablet 500-mg tablet 1/2 tab x 3 3/4 to 11/2 tab x 3 11/2 to 3 tabs x 3 1/4 to 1/2 tab x 3 1/2 to 11/2 tab x 3 2 tabs x 3 Do not administer aspirin in the presence of purpura. PREVENTION AND TREATMENT OF DEHYDRATION Make the patient drink to avoid dehydration. Use oral rehydration solution (ORS) if dehydrated. Notes: If transfer is necessary, give the first injection BEFORE transferring, with a letter indicating the treatment administered. Oily choramphenicol is the treatment of choice for meningitis and should not be used for other pathologies. Leftover vials should be returned to the regional authorities at the end of the epidemic. In the event that stocks run out, contact the regional authorities. References 16

17 1. MSF. Conduite a tenir en cas d epidemie de meningite a meningocoque, MSF. Refugee Health: An approach to emergency situations. MacMillan, WHO. Control of epidemic meningococcal disease. WHO practical guidelines. Lyon: Editions Fondation Marcel Merieux, Flachet L, Boelaert M, Henkens M et al. Intervention en cas d epidemie de meningite: indications et limites. Etudes des interventions realisees par MSF, Journees scientifiques Paris: Epicentre, AEDES, Medecins Sans Frontieres, CDC. Famine-affected, refugee, and displaced populations: Recommendations for public health issues. MMWR, 1992, 41 (RR-13): Moore, P S, Reeves, M W, Schwartz, B, Gellin, B G, Broome, C V. Intercontinental spread of an epidemic group A Neisseria meningitides strain. The Lancet, 1989, 2(8657): WHO in collaboration with CDC, CRED and FINNPREP. Emergency preperadeness and response: Rapid health assessment in mengitis outbreaks. Emergency Relief Operations, Hussey, G. A discussion document presented at WHO clinical research meeting. Banjul, Gambia: CDC. Famine-affected, refugee, and displaced populations: Recommendations for public health issues. MMWR, 1992, 41 (RR-13): MSF. Conduite a tenir en cas d epidemie de rougeole. Paris: Medecins Sans Frontieres, Measles-Recent trends and futur prospects. Wkly Epidemiol Rec, 1994, 69(33): WHO. Responding to a suspected polio outbreak: Case investigation, surveillance and control. Geneva: WHO, WHO/EPI/POL/ Benenson, A. Control of communicable diseases manual. 16 th edition. Washington DC: American Public Health Association, Van Niekerk, Vries, J B et al. Outbreak of paralytic poliomyelitis in Namimbia. The Lancet, 1994, 344: Study questions 17

18 1. Describe the composition of an immunization team for a mass vaccination campaign 2. An immunization team can immunize /hour 500/day /hour /hour 3. Measles vaccine is 50% protective at age 9 months. True or false? 4. Meningococcal vaccination is effective 1 day after vaccination 5-14 days after vaccination 1 week after vaccination None of the above 5. During a meningitis epidemic the peak is usually reached within 2-8 weeks 1 week 2 months 1-3 weeks 6. During a meningitis epidemic there should always be undertaken a mass immunization campaign. True or false? 7. Which is the target group prioritized in a measles vaccination campaign? 8. Which is the target group prioritized in a mengitis vaccination campaign? 9. Which meningococcal serogroups cause epidemics? 10. Meningitis cases should always be diagnosed by laboratory diagnosis with gram stain and culture. True or false and why? 11. In meningitis epidemics the threshold is always 15 cases/100,000/persons/week. True or false? 12. Attack rate in mengitis epidemics ranges from: cases/100,000 population cases/100,000 population 2-10 cases/100,000 population None of the above 13. CFR in mengitis without treatment can be as high as: 90% 10% 40% 70% 14. CFR in measles is usually: <5% 1-6% 90% 10-20% 15. Measles vaccine is contra-indicated in: Pregnancy Malnutrition HIV/AIDS All of the above dosages of measles vaccination should be given at children at 9 months and 2 years of age. True or false? 17. Routine meningitis vaccination is recommended as routine practice in overcrowding situations in order to achieve herd immunity. True or false? 18. Children 2 months to 1 year of age with meningitis should be treated with: Ampicilline Ceftriaxone Chloramphenicol Amoxicillin 18