CHOLERA EPIDEMIOLOGY IN ZAMBIA FROM 2000 TO 2010: IMPLICATIONS FOR IMPROVING CHOLERA PREVENTION AND CONTROL STRATEGIES IN THE COUNTRY.

OBJECTIVE: To review the cholera epidemiology in Zambia from 2000 to 2010 in order to highlight the key lessons learned. Based on our findings, we make recommendations for improving cholera prevention and control in country. DESIGN: Ten years descriptive cholera data was extracted from the national IDSR database and analysed. SETTING: The study was conducted in Zambia using national epidemiology data which were disaggregated by Province. SUBJECTS: None. RESULTS: Starting from 2003, there has been a progressive increase in yearly incidence of cholera in the country. In 2010, 6794 cases (500% increase compared to 2003) and 115 deaths (CFR 1.6%) of the disease were reported with Lusaka Province accounting for 85% of the total cases. Outbreaks start between epidemiological weeks 40 to 45 of the year and ends between weeks 20 to 25 of the following year (which corresponds to the Zambian rainy season). Outbreaks are largely confined to the peri-urban areas of Lusaka, Luapula, Southern and Copperbelt Provinces. CONCLUSION: In the last 10-20 years, the epidemiology of cholera in Zambia has changed; Laboratory confirmation of Vibrio cholerae in the country on a yearly basis in the last ten years suggests that the country is now endemic for cholera hence the need to review current cholera prevention and control strategies.

District specific correlates for hypertension in Kaoma and Kasama rural districts of Zambia.

INTRODUCTION: Hypertension a major risk factor for cardiovascular disease and is the most widely recognized modifiable risk factor for this disease. There is little information on the prevalence and risk factors for hypertension in Zambia, and in particular in rural areas of the country. In order to contribute to the existing global literature on hypertension, particularly in rural Zambia, this study was conducted to determine the prevalence of hypertension and its correlates in two rural districts of Zambia, namely Kaoma and Kasama. METHODS: A cross-sectional study using a modified World Health Organization (WHO) global non communicable diseases (NCD) surveillance initiative NCD-STEPwise approach was used. Proportions were compared using the Yates' corrected χ2 test, and a result yielding a p-value of less than 5% was considered significant. Bivariate and multivariate logistic regression analyses were conducted. Factors that were significantly associated with the outcome in bivariate analyses were considered in a multivariate logistic regression analysis using a backward variable selection method. Adjusted odds ratios (AOR) and their 95% confidence intervals (CI) were reported. RESULTS: In total, 895 participants from Kaoma and 1198 participants from Kasama took part in the surveys. Overall, 25.8% participants (27.5% male, 24.6% female; p=0.373) in Kaoma and 30.3% (31.3% male, 29.5% female; p=0.531) in Kasama were hypertensive. In Kaoma, age and BMI were independently associated with hypertension. Compared with participants aged 45 years or older, participants aged 25-34 years were 60% (AOR=0.40, 95% CI [0.21, 0.56]) less likely to be hypertensive. Participants with BMI <18.5 and 18.5-24.9 were 54% (AOR=0.46, 95% CI [0.30, 0.69]) and 31% (AOR=0.69, 95% CI [0.49, 0.98]) less likely to be hypertensive compared with participants with BMI ≥30. In Kasama, age, smoking and heart rate were significantly associated with hypertension in multivariate analysis. Participants 25-34 years were 49% (AOR=0.51, 95% CI [0.41, 0.65]) less likely to be hypertensive compared with participants 45 years or older. Compared with participants who were non-smokers, smokers were 21% (AOR=1.21, 95% CI [1.02, 1.45]) more likely to be hypertensive. Participants who had heart rate >90 beats/min were 59% (AOR=1.59, 95% CI [1.17, 2.16]) more likely to be hypertensive compared with participants who had heart rate 60-90 beats/min. CONCLUSIONS: The findings reveal that hypertension is prevalent among rural residents in Kaoma and Kasama, Zambia. The disease is highly associated with age, BMI, smoking and heart rate. Efficient preventive strategies are needed to halt the growing trend of non-communicable diseases through the control of risk factors highlighted in this study.

Ultrasound elastography using a regularized modified error in constitutive equations (MECE) approach: a comprehensive phantom study.

Many of the current techniques in transient elastography, such as shear wave elastography (SWE) assume a dominant planar shear wave propagating in an infinite medium. This underlying assumption, however, can be easily violated in real scenarios in vivo, leading to image artifacts and reconstruction errors. Other approaches that are not bound to planar shear wave assumption, such solutions based on the partial differential equation, can potentially overcome the shortcomings of the conventional SWE. The main objective of this paper is to demonstrate the advantages of the modified error in constitutive equations (MECE) formulation with total variation regularization (MECE + TV) over SWE in reconstructing the elastic moduli of different tissue-mimicking phantoms. Experiments were conducted on phantoms with inclusions of well-defined shapes to study the reconstruction of specific features relevant to practical applications. We compared the performances of MECE + TV and SWE in terms of quantitative metrics to estimate reconstruction accuracy, inclusion shape recovery, edge preservation and edge sharpness, inclusion size representation, and shear elasticity and contrast accuracies. The results indicate that the MECE + TV approach outperforms SWE based on several of these metrics. It is concluded that, with further development, the proposed method may offer elastography reconstructions that are superior to SWE in clinical applications.

Age at first dose of measles vaccination in Ethiopia.

BACKGROUND: Although measles vaccination is recommended to be given at nine months of age in Ethiopia and in most of sub-Saharan Africa, no information is available about the age at which children actually receive their first dose of measles vaccine. This has important implications in terms of preventing infection and averting epidemics of measles. OBJECTIVE: To determine the age at which Ethiopian children actually receive their first dose of measles vaccine. DESIGN: Cross sectional study. SETTING: All major vaccination facilities including private and non-governmental health facilities that were registered with the Addis Ababa city Administration Health Bureau. SUBJECTS: A total of 17,674 records of children who received measles vaccination in health facilities were reviewed and in rural areas 615 children were surveyed over one year period September 2004 to August 2005. RESULTS: In both the urban and the rural settings the median age of children at first dose of measles vaccination was nine months. In the rural areas only 19.8% of children had vaccination cards. Measles coverage by card and history in rural areas was 84.4%. Many children from the rural site received measles vaccination during supplemental immunisation activities (SIAs) rather than from routine vaccination programmes. Measles coverage significantly varies among sub-cities in Addis Ababa. CONCLUSION: Vaccination practices and measles coverage levels do not support delaying the first measles vaccine dose. Strengthening the routine vaccination programmes must receive priority before changing recommended age for the first dose of measles vaccine.

Polio outbreak response in Ethiopia.

BACKGROUND: Ethiopia had been polio-free for almost four years until December 2004. However, between December 2004 and February 2006, 24 children were paralysed as a result of infection with wild poliovirus imported from the neighbouring country of Sudan. In response, the country has attempted to document the impact of various response measures on the containment of wild poliovirus transmission. OBJECTIVES: This study aims at systematic and epidemiological assessment of the extent of the outbreak, its determinants, and the lessons learned as well as the implications for future control strategies to interrupt wild poliovirus transmission. DESIGN: A cross-sectional study design with qualitative and quantitative data collection approaches was used to conduct the epidemiologic assessment. SUBJECTS: All confirmed wild poliovirus cases, and reported acute flaccid paralysis cases in close proximity to the confirmed polio cases were the study subjects. Child caretakers and health service providers were interviewed as part of the investigation. RESULTS: Between December 2004 and February 2006, eight children from Tigray Regional State, nine children from Amhara Regional State and seven children from Oromia Regional State were paralysed as a result of infection with wild poliovirus type 1. Genetic sequencing demonstrated two separate importations to Ethiopia. Risk factors that may have facilitated spread of the outbreak within the country included gaps in vaccination coverage and interruption of the cold chain system, gaps in acute flaccid paralysis surveillance performance, high population mobility, poor environmental sanitation, crowded living conditions and unsafe drinking water. In response to the outbreak, Ethiopia conducted detailed outbreak investigations within two days of confirmation of the index cases. Large-scale, house-to-house vaccination campaigns were also implemented. As a result, the three regions interrupted the wild poliovirus transmission within the regions within one year of confirmation of the index case. CONCLUSION: Outbreak response activities were successful in interrupting the imported wild poliovirus transmission in Tigray, Amhara and Oromia Regional States of Ethiopia within a one-year period of time. In Ethiopia, programme strategies should be intensified to contain further spread and prevent future importation of wild poliovirus. Large-scale immunisation campaigns should reach every child, including those isolated by geography, poverty and security.

Malaria epidemics in the highlands of Ethiopia.

OBJECTIVE: To confirm the occurrence and describe the patterns of the 2003 malaria epidemics reported in the highlands of Ethiopia. DESIGN: A retrospective descriptive study. SETTINGS: Fifty epidemic affected districts between altitude ranges of 1500 and 2500 m in three regions in Ethiopia. RESULTS: Exaggerated seasonal transmission was observed in 25 districts, 16 in Oromia region and 9 in SNNPR. A sustained upward trend with 3-4 consecutive abnormal seasonal transmissions, which has started since 2002, has been identified in 22 districts. True explosive epidemic malaria was recorded at exceptionally high altitude (around 2500m) in at least one of the health facilities in seven districts. The incidence of malaria in 2003 epidemic has showed a six fold increase on average (range 2-20) from the threshold level. CONCLUSION: Occurrence of a malaria epidemic was confirmed in all studied districts showing that the level of malaria endemicity and magnitude of the problem is increasing. The findings suggest the strategic importance of taking well-timed and appropriately targeted preventive and control interventions.

Safety and efficacy of artemether-lumefantrine in the treatment of uncomplicated falciparum malaria in Ethiopia.

OBJECTIVE: To document baseline data on the efficacy and safety of artemether-lumefantrine for the treatment of uncomplicated falciparum malaria in Ethiopia. DESIGN: Patients diagnosed for P. falciparum, who were treated with six doses of artemether-lumefantrine over three days, were followed for 28 days and treatment outcomes classified based on the WHO (2003) protocol. SETTING: Four health facilities located in malarious areas in two regions: Alamata and Humera hospitals in Tigray region and Assendabo and Nazareth in Oromia region. SUBJECTS: Patients with body weight of more than 10 kgs, excluding pregnant women, who or their guardians consented to participate in the study after fulfilling the inclusion criteria were enrolled in the study for a follow-up period of 28 days. MAIN OUTCOME MEASURES: Proportion of treatment success and adverse drug effects that required discontinuation of treatment and/or follow-up. RESULTS: A total of 213 patients who fulfilled the enrolment criteria completed the 28 days follow-up after treatment with artemether-lumefantrine. A treatment success rate of 99.1% (95% confidence interval [CI] 96.9, 99.8) and no adverse effects or complaints related to the drug that required discontinuation of treatment or withdrawal from follow-up was reported. Treatment success was not achieved in 213 (0.9%) subjects for whom fever and peripheral parasitaemia was demonstrated on day 21 and 28. The day 21 and day 28 blood samples of the treatment failure cases were not PCR corrected. CONCLUSION: The artemisinin based combination drug artemether-lumefantrine has shown very high (99.1%) clinical and parasitological cure for the treatment of uncomplicated falciparum malaria with no reports of adverse reaction that required withdrawal of treatment or discontinuation of follow-up. In the presence of the low efficacy of sulfadoxine-pyrimethamine, chloroquine and amodiaquine, the use of artemether-lumefantrine for the treatment of uncomplicated falciparum malaria is the best choice for Ethiopia.

Efficacy of sulfadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria in Ethiopia.

OBJECTIVE: To assess the status of the therapeutic efficacy of sulfadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria to enable evidence based policy decisions. DESIGN: The study used the new WHO (2003) protocol for the assessment of the therapeutic efficacy of anti-malarial drugs. SETTING: Eleven health facilities located in malarious areas with seasonal transmission. SUBJECTS: Patients aged six months and above who presented to the health facilities for febrile illness and for whom consent was obtained to participate in the study after fulfilling the inclusion criteria were enrolled in the study. MAIN OUTCOME MEASURES: Proportion of treatment failures. RESULTS: In eleven (90.9%) of the sites, where adequate sample was collected, a total of 598 subjects were enrolled and 487 (81.4%) completed the follow-up. A mean treatment failure rate of 35.9% (95% confidence interval [CI] 31.8, 40.3) on the 14 days follow-up and 71.7% (95% CI 67.5, 75.9) on the 28-days follow-up was recorded (not PCR corrected). The mean clinical failure on the 14-days follow-up was 20.9% (95% CI 17.5, 24.7) and 70% (n=10) sites had aggregated clinical failure rates higher than 15%, while in 80% (n=10) sites the total treatment failure exceeded 25%. There was no significant difference in treatment failure rates in areas with malaria transmission duration of six months and above as compared to areas with below six months of transmission (odds ratio [OR] = 0.9, 95% CI 0.43,1.83 p = 0.75). The difference in mean treatment failure between the <5 and > or =15 years of age was not significant (OR 0.8, 95% CI 0.39,1.67 P = 0.54). CONCLUSION: The level of treatment failure detected is much higher than the WHO recommended tolerable levels. The findings, therefore, strongly indicate the need for an immediate review of the existing national anti-malarial treatment guideline.

Cluster survey for poliomyelitis and neonatal tetanus in Ilorin, Nigeria.

The incidence of poliomyelitis and neonatal tetanus in Ilorin Local Government Area was estimated using a 40-cluster, retrospective survey of neonatal tetanus deaths and lameness from poliomyelitis in March and April 1988. The survey identified 19 neonatal tetanus deaths among 1601 livebirths, giving an incidence rate of 14.9/1000 livebirths. Some 31 residual paralytic polio cases were identified among 4576 children aged five to nine years, giving a prevalence rate of 6.8/1000 children in this age group and an annual incidence rate of 38.3/100,000 general population. Immunization of pregnant women with tetanus toxoid, had a greater impact on mortality from neonatal tetanus than delivery in hospital or birth at home attended by a traditional birth attendant. Antenatal coverage with two doses of tetanus toxoid was 62.6%. Poliomyelitis and neonatal tetanus still constitute important causes of childhood morbidity and mortality in Ilorin and antenatal tetanus immunization coverage is not yet sufficient to control neonatal tetanus in this population. The target age for immunization with tetanus toxoid should be extended to include all women of childbearing age. Further retrospective surveys from other Nigerian states are needed to determine the magnitude of the neonatal tetanus problem throughout the country.

Prevalence of paralytic poliomyelitis in children of Kwara State, Nigeria: report of a house-to-house survey.

During March 1988, a house-to-house survey was carried out to determine the prevalence of poliomyelitis in Ilorin Local Government Area (LGA) of Kwara State, Nigeria. The survey identified 4576 children aged 5 to 9 years old in the households visited from forty randomly selected clusters in the area. Of the 41 lame children, lameness compatible with paralytic poliomyelitis was found in 31, of these 87% had their condition before the age of 3 years. Thirteen percent needed a stick support for walking while 16% were unable to walk even with support. The prevalence rate of residual polio paralysis was 6.8/1000 children 5-9 years old. When all cases of residual paralysis, deaths and recoveries are taken into account, this translates to an incidence of 8.4/1000 children aged 5-9 years old and an annual incidence of 38.3/100,000 general population.

Management of diarrhoea at the household level: a population-based survey in Suleja, Nigeria.

Home management of diarrhoea was studied in 1,638 children under 5 years of age whose 1,160 mothers we randomly selected in Suleja local government area (LGA) in November 1991. The sampling method used was a cluster scheme based on "probability proportionate to size", with 40 clusters randomly selected. Prevalence of diarrhoea during the two preceding weeks was 20.8%; 73.8% of the cases were in children under two years of age; 32% of the children had received no treatment, and 56% of the mothers had used health facilities (Government and private). The estimated annual incidence rate of diarrhoea disease was 4.6 episodes per child. During episodes of diarrhoea, almost all mothers continued breast-feeding and giving other available home fluids, but 42.2% stopped solid food. Forty-four percent of mothers gave sugar-salt-solution (SSS) at home for diarrhoea; nearly half (45.3%) of them could not prepare the solution correctly. Mothers treated at home with SSS, herbs and fluids significantly more often when the diarrhoea was perceived as severe. Mothers sought help outside the home (at a health facility or traditional healer) significantly more often for severe cases. The survey provides important information about what happens at home - the place where diarrhoeal disease control programmes succeed or fail. The findings highlight the communication messages that need to be devised for mothers. Since government health facilities remains the commonest (87%) source of information on diarrhoea, health workers need to be equipped with the skills for advising mothers on management of diarrhoea in the home.

Monitoring impact of oral poliovirus vaccine on poliomyelitis trends from physiotherapy records, Ilorin, Nigeria, 1981-1988.

During the eight years of a poliomyelitis control programme in Ilorin Local Government Area, Nigeria, 85% of children aged 12-23 months were estimated to have received three doses of trivalent oral polio vaccine. The estimated incidence of paralytic poliomyelitis decreased by 59%, indicating a low vaccine efficacy for the currently used TOPV. This has a serious implication for the World Health Organization's global poliomyelitis eradication strategy of immunizing at least 80% of children aged one year by the year 2000, that eradication may not be achieved by this strategy alone in tropical Africa. Supplementary strategies of mass OPV campaigns, combined IPV/OPV vaccine regimens, or the introduction of new generation of poliomyelitis vaccines may be needed. Similar low-cost efforts at documenting the impact of TOPV on the incidence of poliomyelitis using physiotherapy clinics as independent sentinels, are needed from other states of Nigeria. To increase the efficacy of the primary series of TOPV in Nigeria, the number of doses constituting the primary series should be increased to four (including one at birth). There is now reason to consider a properly timed combination of both IPV and OPV in Nigeria.

Reasons for non-use of family planning methods at Ilorin, Nigeria: male opposition and fear of methods.

This study reports the main reasons given for non-use of contraception by non-pregnant women aged 15-44 years, who are at risk of unplanned pregnancy and living in the Ilorin Local Government Area of Kwara State, Nigeria. Six hundred and forty-six women were derived from a stratified cluster sample and interviewed using a questionnaire. Almost one-third (31.4%) of respondents gave male opposition to family planning as the reason for current non-use. Another 13.3% expressed fear of methods, 6.3% did not want to use contraception until the first child was born, and 13.6% until the desired number of children were born. Sociodemographic variables including age, educational level, religion, and residence as reasons for non-use were reported. Other important findings included a high awareness of, low availability of, or poor accessibility to contraceptive methods. Short and long term intervention strategies using information, education and communication materials are proposed to combat low levels of contraceptive use in this area.

PIP: This study addresses the main reasons for non-use of contraception by non-pregnant sexually active females. A survey was carried out in Ilorin area of Nigeria where household units were randomly selected by using a clustering method sampling frame. Data was collected from personal interviews on 646 women. 79% of the women were between 20-39 yrs, 77% were Moslems, 67% had no formal education and 84% of the women were married. The average total fertility rate was 4.8 live births per woman, and a mean abortion rate of 1 per woman. All women reported to be knowledgeable on the use of contraceptives and the supply source, although only 27% of the women had previously used contraceptives. Reasons for non-use of contraceptives included 1) husband's rejection of contraceptive method, and 2) fear of method of contraceptives. Also a higher % did not use contraceptives until the first baby born. Thus it was proposed that long and short term methods needed to be used to combat non-use of contraception. A long term strategy should address the male perception of family planning and womanhood, whereas the short term strategy could address issues concerning the safety of contraceptives and dispel myths and negative rumors with regards to contraceptives.

Use of physiotherapy records to monitor the efficacy of a poliomyelitis vaccination programme in Ilorin, Nigeria 1981-1988.

During the 8 years of a poliomyelitis control programme in Ilorin Local Government Area, Nigeria, a maximum of 85% of children aged 12-23 months were estimated to have received three doses of trivalent oral polio vaccine (TOPV). The estimated incidence of paralytic poliomyelitis decreased by 65%, suggesting a low vaccine efficacy of approximately 76% for the currently used TOPV. A more detailed study of TOPV efficacy (eg case control or cohort study) is required, however, to provide a more accurate estimate. Similar low-cost efforts at documenting the impact of TOPV on the incidence of poliomyelitis, using physiotherapy clinics as independent sentinels, are needed from many other centres. To increase the efficacy of the primary series of TOPV in Nigeria, the number of doses constituting the primary series should be increased to four (including one at birth), as recommended by the World Health Organization.

EPI sentinel surveillance for Kwara, 1982-1987.

A comprehensive review of the EPI sentinel surveillance data for Kwara State, Nigeria was conducted for the years 1982--1987 to evaluate programme impact. Measles vaccination coverage moved up from 26 percent in 1984 to between 54 percent and 58 percent in Ilorin, LGA, Kwara State, Nigeria from 1986 to 1988. During the period of review, the annual number of measles cases and the incidence rate of measles reported by the surveillance system has continued to fall from 1985, the year the revised EPI programme was launched in Ilorin LGA. There was infact a forty-one percent reduction in measles incidence in Ilorin LGA in 1987, but measles is still an important cause of preventable morbidity and mortality in the area. Twenty-two percent of reported measles cases occurred in children under nine months of age, children who are younger than the recommended age of vaccination. Two results expected in a partially vaccinated population, a reduction in measles incidence greater than the level of vaccination coverage and a shift in the age-distribution of measles to older children, have not been observed. Measles control in Ilorin LGA will require a vaccination coverage higher than 58 percent. Also, given the age-specific risk of measles infection there, a measles vaccine that would be effective when given before nine months of age would be an important element in controlling measles transmission. Because the epidemiology of measles in Ilorin is a likely consequence of its urban environment, such a vaccine would represent a significant advance toward the control of measles in urban Africa.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral rehydration of children with diarrhoea in Nigeria: a 12-year review of impact on morbidity and mortality from diarrhoeal diseases and diarrhoeal treatment practices.

Diarrhoea diseases continue to be one of the most important causes of morbidity and mortality in the developing world, particularly among young children. Recognizing the importance of the diarrhoeal problem, the World Health Organization has established a global programme for the control of Diarrhoeal Diseases (CDD). The widespread use of ORT is an important part of this programme. In Nigeria, a nationwide execution of the CDD began in 1986. In view of the huge population of Nigeria, an evaluation of the efficacy of the CDD programme at reducing morbidity and mortality from diarrhoeal diseases has national and global importance. Analysis of the available data shows that there has been clear reduction in reported morbidity from dysentery since 1982, with a sharp decline in 1988, and that the incidence of cholera, typhoid, and paratyphoid are all on the increase since 1982. An analysis of community-based CDD survey data revealed minimal, but insignificant impact on diarrhoeal diseases incidence and diarrhoeal treatment practices in Nigeria from 1986 to 1989. Using the technique of decision analysis, the total annual number of acute diarrhoeal episodes for children under 5 years old in Nigeria was estimated to be 83.2 million and this may have been responsible for at least 314,200 deaths in this age group in 1989 alone, despite the implementation of the CDD programme. CDD interventions, by their very nature, are problematic to evaluate. In fact, evaluation may be one of the most challenging and frustrating aspects of the whole programme. Thus far, CDD in Nigeria is short of its goals.

A 10-year review of morbidity from childhood preventable diseases in Nigeria: how successful is the expanded programme on immunization (EPI)? An update.

Morbidity and mortality in children of developing countries are primarily due to preventable infectious diseases such as measles, poliomyelitis, tuberculosis, whooping cough, diphtheria, and tetanus. By 1990 WHO hopes to have every child in the world immunized against these six diseases, that was why the Expanded Programme on Immunization (EPI) was launched. In Nigeria, a nationwide execution of EPI began in 1979. In view of the huge population of Nigeria, an evaluation of the efficiency of the EPI programme at reducing morbidity and mortality from the six target diseases has national and global importance. One such analysis of disease trends showed that apart from tuberculosis and acute poliomyelitis there was no clear reduction in morbidity from the EPI target diseases between 1979 and 1983. The programme was revised and relaunched nationwide in 1984. This paper attempts to update documented programme achievements by including information on EPI diseases from 1974 to 1988. An analysis of available data shows that there has been clear reduction in morbidity from measles and whooping cough since 1986, and that the incidence of tuberculosis is on the increase from 1984, despite a national BCG coverage of over 80 per cent. It is suggested that future evaluations should include data on community-based surveys on poliomyelitis and neonatal tetanus, and use the technique of decision analysis to estimate EPI impact on mortality. A similar effort in this paper predicted a 42 per cent morbidity and 37 per cent mortality reductions from EPI target diseases in Nigeria by the end of 1989.

Loss of maternally-acquired measles antibody during infancy in Ilorin, Nigeria.

In a study of the prevalence of measles antibody in infants aged 1-9 months detectable antibody was present in 32 per cent. Prevalence was highest in the 4-7 week age group and dropped rapidly with increasing age. In infants 28-35 weeks old, only 7 per cent had detectable antibody. Logistic regression analysis showed that by the end of the seventh month of life only 10 per cent would carry antibody against measles.