Sensitivity of poliomyelitis surveillance in India.

OBJECTIVE: To estimate the sensitivity of poliomyelitis surveillance in India. DESIGN: A comparison of two sets of data obtained from lameness surveys and routine surveillance system. METHODS: Lameness surveys were undertaken by the Ministry of Health and Family Welfare in 1981, 1989 and 1992 using 30-cluster sampling technique. These data were compared with the number of polio cases reported through routine surveillance system. RESULTS: Based on the 1981 survey which was undertaken near the initiation of routine immunization with oral polio vaccine (OPV) in India, poliomyelitis incidence was estimated at 25 cases per 100,000 population. Subsequent studies in 1989 and 1992 estimated a decrease in incidence rates to 15.7 and 6.3 cases per 100,000 population, respectively. Comparing the number of reported cases with the survey estimates provided a measure of the sensitivity of (completeness of reporting) surveillance; the sensitivity increased from 8% in 1981, to 20% in 1989, to 32% in 1992. CONCLUSION: The results are encouraging when compared with the global estimates of 10% reporting in 1993. Nevertheless, there is a need for further improvement in the completeness of reporting of poliomyelitis cases to detect all the cases of acute flaccid paralysis to allow epidemiological investigations and effective follow-up action which is critical to interrupt wild virus transmission.

Sensitivity of neonatal tetanus surveillance system in India.

OBJECTIVE: To estimate the sensitivity of neonatal tetanus (NNT) surveillance in India. DESIGN: A comparison of two sets of data obtained from NNT mortality surveys and routine surveillance system. METHODS: NNT mortality surveys were undertaken in 1981, 1989 and 1992 using 30 cluster sampling technique. The data on reported incidence of NNT through routine surveillance system was taken from the published documents of Health Ministry and WHO. RESULTS: In 1981, the incidence of disease in a national survey was estimated to be 4 and 16.4 per 1000 live births in urban and rural areas, respectively. Follow up surveys in 1989 and 1992 estimated the overall incidence as 4 and 1.74 per 1000 live births, respectively. Comparing the reported and estimated by surveys, around 10% of NNT cases were reported. CONCLUSIONS: There is an urgent need to strengthen the routine surveillance system which at present grossly under-reports the NNT incidence in India.

Immunization, oral rehydration therapy and malaria chemotherapy among children under 5 in Bomi and Grand Cape Mount counties, Liberia, 1984 and 1988.

As part of an evaluation of child survival programmes in 13 African countries, cluster surveys were carried out in two Liberian counties in 1984 and 1988 to measure use of three primary health care services: immunization of infants, antimalarial treatment of children with fever, and oral rehydration of childhood diarrhoea. Immunization rates increased (30-53% for DPT-1 and 13-33% for measles), treatment of malaria with drugs available in the home increased from 5 to 35%, and home use of sugar-salt solution to prevent dehydration remained essentially unchanged, 5.9% in 1984 and 3.8% in 1988.

Immunization opportunities taken and missed.

A significant proportion of nonvaccination is the result of the failure of the health system to make use of every opportunity for immunization. Answers to the four questions: Who is not vaccinated? Where could vaccinations have been given? When could vaccinations have been given? and Why were vaccinations not given? are important to understanding the epidemiology of nonvaccination.

Cost-effectiveness of immunization in The Gambia.

Cost-effectiveness studies were carried out in The Gambia to estimate costs of preventing childhood morbidity and mortality through immunization. For the four priority diseases--neonatal tetanus, pertussis, measles and poliomyelitis--costs per case prevented ranged from $1.30 for pertussis to $655.54 for poliomyelitis. In terms of preventing childhood deaths through immunization, measles at $40.83 per death prevented, pertussis at $99.85 per death prevented and neonatal tetanus at $152.53 per death prevented were most cost-effective. For developing countries, immunization is an efficient use of limited health resources.

Evaluating immunization services.

PIP: The purpose of evaluating immunization programs is to measure progress made toward predetermined objectives. These objectives include access, immunization delivery, coverage, and disease reduction. Evaluation should be carried out at the operational level, the district level, and the national level. Guidelines for delivery level examination include: meeting all scheduled immunizations; sufficiency of vaccines; checking and recording refrigeration temperatures on a daily basis; screening of all patients for vaccination status; and comprehensive instructions for guardians of each child as to the need for future immunizations and return visits. Monthly evaluation guidelines concern percentages of target group immunizations and the identification of preventable diseases in the immunized group. The questions of which actions will prevent these diseases, as well as how to better inform the public regarding the importance of immunizations are part of the monthly evaluation. National level evaluation should focus on subunit performance and national progress toward objectives. Direct monitoring is effective in evaluating subunit performance as is indirect monitoring through examination of monthly reports. The 5 areas that should be monitored in evaluating national progress are strategies, training, logistics, coverage, and disease reduction. The data used in these evaluations include: information about the pre-immunization status of a population; epidemiologic data; data on vaccination coverage; and data on vaccine effectiveness; and changes in disease occurrence. Personnel responsible for immunization at different levels should not be given a cumbersome methodology. Clear, simple questions should be developed that allow accurate, easy data collection. This allows for evaluation of progress, identification of problems, and the implementation of solutions.^ieng

Control of poliomyelitis in Africa.

In Africa, an estimated 168,000 children are disabled by poliomyelitis every year. With the use of lameness surveys to estimate incidence before immunization, surveys to measure vaccination coverage, and surveillance to monitor disease trends, poliomyelitis control in Yaound é, Cameroon; The Gambia; and Abidjan, Ivory Coast was examined. Three doses of oral poliovirus vaccine have been administered to 50%-70% of the children. The incidence of poliomyelitis has decreased significantly. Oral poliovirus vaccine administered during the first year of life has been effective in controlling poliomyelitis in tropical Africa.

Measles control in Yaounde: justification of a one dose, nine month minimum age vaccination policy in tropical Africa.

For tropical countries the World Health Organisation recommends a single dose of measles vaccine, administered at a minimum age of 9 months. In some African nations, however, up to 26% of all reported measles occurs before the age of 9 months, and many African nations have been reluctant to follow the WHO recommendation. In 1974 the Ministry of Health of the United Republic of Cameroon made several changes in the existing measles control strategy, including increasing the minimum age for measles vaccination from 6 to 9 months. Surveillance of measles in Yaounde, the capital city, during the five years after the increase in age at vaccination did not reveal a need to return to the minimum age of 6 months. In fact, by 1979, with measles vaccination coverage among children 12-23 months of age at 40%, there had been a 44% decrease in reported measles among children of all ages, including a 64% decrease in the measles attack rate among children under the age of 9 months. These observations support the one dose, 9 month minimum age measles vaccination policy in tropical Africa.

Microtiter determination of measles hemagglutination inhibition antibody with filter papers.

Epidemiological studies of measles and measles immunization frequently require determination of measles antibody status. In developing countries, where venipuncture is frequently unacceptable and where refrigerated storage of serum specimens is often unavailable, microtiter techniques not requiring refrigeration are required. We developed a filter paper technique that measures measles hemagglutination inhibition antibody and meets these criteria. Comparison of separately collected venous blood and peripheral blood collected on filter paper demonstrated 97% agreement in terms of presence or absence of antibody. In 30 of 32 measles specimens, 94% of titers were the same or varied by less than 2 twofold dilutions.

Immunofluorescence staining for detection of variola virus.

In September 1975 Bangladesh was the only country in the world with endemic variola major, and the eradication of the disease was imminent. A rapid and accurate laboratory diagnostic method was required to supplement immunodiffusion in agar gel and culture on chorioallantoic membrane of embryonated egg available at the Institute of Public Health in Dacca, Bangladesh. To determine its effectiveness, a new, improved immunofluorescence (IF) staining technique was introduced. Laboratory specimens (scabs or vesicular or pustular impressions) were collected from patients who had, or were suspected of having, smallpox. Seventy-eight of 144 specimens collected were found to be IF positive for smallpox. As the number of laboratory-positive cases far exceeded the number of clinically diagnosed smallpox cases, IF-positive cases were reinvestigated and subsamples of the IF-positive specimens were tested at a World Health Organization poxvirus reference laboratory at the Centers for Disease Control in Atlanta, Ga. The results indicated 100% sensitivity for the IF technique (no false-negative results) in diagnosing variola major but also showed a high rate of false-positive results. Consequently, IF could not be recommended as a routine screening test for smallpox.

Smallpox surveillance in Bangladesh: I - Development of surveillance containment strategy.

A major epidemic of Variola major with an estimated 90 000 cases and 18 000 deaths occurred in Bangladesh in 1972. During a 3-year period methods of active surveillance (market search, outbreak investigation, and house-to-house search) were developed to supplement the passive reporting system. The percentage of smallpox cases detected increased from 11.8% in 1972 to 83% in 1975. Together with the implementation of improved methods of outbreak control, smallpox transmission was interrupted in October 1975.

Smallpox surveillance in Bangladesh: II - Smallpox facial scar survey assessment of surveillance effectiveness.

A smallpox facial scar survey of 465 892 persons aged 0-19 years was carried out in Bangladesh in 1976, covering approximately 1% of the 0-19 year old population. Of the 4 306 persons found with facial scarring consistent with previous smallpox infection, none had a history of smallpox with onset after the last reported case on October 16, 1975. Histories taken from persons with facial scars allowed smallpox incidence to be estimated for each year from 1972 to 1975. These estimates indicate that completeness of reporting increased steadily from 11.8% in 1972 to 83.0% in 1975, reflecting the increasing effectiveness of surveillance.

Gastroenteritis due to rotavirus in an isolated Pacific island group: an epidemic of 3,439 cases.

In the spring of 1964, 3,439 cases of acute gastroenteritis were reported from Truk District, an island group in the mid-Pacific. The causative agent was not identified in laboratory studies performed in that year. Retrospective serologic studies 15 years later with the complement fixation test and the enzyme-linked immunosorbent assay provided serologic evidence that this outbreak was caused by the human rotavirus that was first isolated in 1973.

Experimental smallpox in chimpanzees.

In an attempt to prepare highly specific antiserum to variola virus, a chimpanzee was inoculated with a virulent human strain of this virus. Three uninoculated chimpanzees were housed in the same room; two of these developed clinical disease with seroconversion, while the third developed no evidence of infection and no antibody. The three animals that became ill also developed antibody to vaccinia and monkeypox viruses. Human contacts during the study and following a break in containment showed no evidence of infection as determined by serological tests and lack of clinical disease.