TZA-NBS-HMIS-2007-v01
Tanzania HIV/AIDS and Malaria Indicator Survey 2007-2008
Name | Country code |
---|---|
Tanzania | TZA |
Demographic and Health Survey [hh/dhs]
The 2007-2008 Tanzania HIV/AIDS and Malaria Indicator Survey is the eight national survey to be carried out as part of the Demographic and Health Surveys project in Tanzania. It is the second comprehensive survey on HIV/AIDS carried out in Tanzania.
The primary objectives of the 2007-08 THMIS survey were to provide up-to-date information on the prevalence of HIV infection among Tanzanian adults, and the prevalence of malaria infection and anaemia among children under age five years. The findings will be used to evaluate ongoing programmes and to develop new health strategies. Where appropriate, the findings from the 2007-08 THMIS are compared with those from the 2003-04 Tanzania HIV/AIDS Indicator Survey (THIS).
The findings of these two surveys are expected to complement the sentinel surveillance system undertaken by the Ministry of Health and Social Welfare under its National AIDS Control Programme (NACP). The THMIS also provides updated estimates of selected basic demographic and health indicators covered in previous surveys, including the 1991-92 Tanzania Demographic and Health Survey (TDHS), the 1996 TDHS, the 1999 Reproductive and Child Health Survey (RCHS), and the 2004-05 TDHS.
More specifically, the objectives of the 2007-08 THMIS were:
• To measure HIV prevalence among women and men age 15-49
• To assess levels and trends in knowledge about HIV/AIDS, attitudes towards people infected with the disease, and patterns of sexual behaviour;
• To collect information on the proportion of adults who are chronically sick, the extent of orphanhood, levels of and care and support;
• To gauge the extent to which these indicators vary by characteristics such as age, sex, region, education, marital status, and poverty status; and
• To measure the presence of malaria parasites and anaemia among children age 6-59 months.
The results of the 2007-08 THMIS are intended to provide information to assist policymakers and programme implementers to monitor and evaluate existing programmes and to design new strategies for combating the HIV/AIDS epidemic in Tanzania. The survey data will also be used as inputs in population projections and to calculate indicators developed by the United Nations General Assembly Special Session (UNGASS), the UNAIDS Programme, and the World Health Organization (WHO).
Sample survey data [ssd]
Household and Individual
Version 01(Public use file for web dissemination)
2007-08
The scope of the Tanzania HIV/AIDS and Malaria Indicator Survey 2007-2008 includes:
Household Questionnaire: Household Identification, Interviewer Visits, Household Schedule, Household Characteristics,
Individual Questionnaire: Background Characteristics, Education, Employment, Marriage, Sexual Activity, Support for persons who have died, Support for orphans and vulnerable children, Anaemia and Malaria testing for children age 0-5
Topic | Vocabulary | URI |
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HEALTH [8] | CESSDA | http://www.nesstar.org/rdf/common |
Tanzania Mainland and Zanzibar
Clusters
Women and Men age 15-49
Name | Affiliation |
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National Bureau of Statistics | Ministry of Finance and Economic Affairs |
Name | Role |
---|---|
Tanzania Commission for AIDS | Mobilise Resources and Monitoring |
Zanzibar AIDS Commission | Moblise Resources and monitoring |
Ministry of Health and Social Welfare | Authorised the Survey |
National AIDS Control Programme | Technical Assistance |
National Malaria Control Programme | Technical Assistance |
United Nation Food Programme Agency | Technical Assistance |
United Nation Development Programme | Technical Assistance |
MKUKUTA Secretariat | Technical Assistance |
Muhimbili University College of Health and Allied Sciences | Technical Assistance |
Name | Role |
---|---|
United States Agency for International Development | Financial Support |
The sampling frame used for the 2007-08 THMIS is the same as that used for the 2004-05 TDHS, which was developed by NBS after the 2002 Population and Housing Census (PHC). The sample excluded nomadic and institutional populations, such as persons staying in hotels, barracks, and prisons. The THMIS utilised a two-stage sample design. The first stage involved selecting sample points (clusters) consisting of enumeration areas delineated for the 2002 PHC. A total of 475 clusters were selected. The sample was designed to allow estimates of key indicators for each of Tanzania’s 26 regions. On the Mainland, 25 sample points were selected in Dar es Salaam and 18 in each of the other 20 regions. In Zanzibar, 18 sample points were selected in each of the five regions, for a total of 90 sample points.
A household listing operation was undertaken in all the selected areas prior to the fieldwork. From these lists, households to be included in the survey were selected. The second stage of selection involved the systematic sampling of households from these lists. Approximately 16 households were selected from each sampling point in Dar es Salaam, and 18 households per sampling point were selected in other regions. In Zanzibar, approximately 18 households were selected from each sampling point in Unguja, and 36 households were selected in Pemba to allow reliable estimates of HIV prevalence for each island group. Because of the approximately equal sample sizes in each region, the sample is not selfweighting at the national level, and weighting factors have been added to the data file so that the results will be proportional at the national level. In the selected households, interviews were conducted with all women and men age 15-49. The THMIS also collected blood samples for anaemia and malaria testing among children age 6-59 months, and dried blood spot (DBS) samples for HIV testing among women and men age 15-49
QUESTIONNAIRES
Two questionnaires were used for the 2007-08 THMIS: the Household Questionnaire and the Individual Questionnaire. The questionnaires are based on the standard AIDS Indicator Survey and Malaria Indicator Survey questionnaires, adapted for the population and health issues relevant to Tanzania. Inputs were solicited from various stakeholders representing government ministries and agencies, non governmental organizations, and international partners. After the preparation of the definitive questionnaires in English, questionnaires were translated into Kiswahili.The Household Questionnaire was used to list all the usual members and visitors of selected households. Some basic information was collected on the characteristics of each person listed, including his or her age, sex, education, and relationship to the head of the household. For children under age 18 years, survival status of the parents was determined. If a child in the household had a parent who was sick for more than three consecutive months in the 12 months preceding the survey or a parent who had died, additional questions related to support for orphans and vulnerable children were asked. The Household Questionnaire also included questions on whether household members were seriously ill and whether anyone in the household had died in the past 12 months. In such cases, interviewers asked whether the household had received various kinds of care and support, such financial assistance, medical support, social or spiritual support.
The Household Questionnaire was also used to identify women and men who were eligible for the individual interview and HIV testing. The Household Questionnaire also collected information on characteristics of the household dwelling, such as source of water, type of toilet facilities, materials used to construct the house, ownership of various durable goods, and ownership and use of mosquito nets.
Furthermore, the Household Questionnaire was used to record haemoglobin and malaria testing results for children age 6-59 months.
The Individual Questionnaire was used to collect information from all women and men age 15-49. These respondents were asked questions on the following topics:
• Background characteristics (education, residential history, media exposure, employment,etc.);
• Marriage and sexual activity;
• Knowledge about HIV/AIDS and exposure to specific HIV-related mass media programmes;
• Attitudes towards people living with HIV/AIDS;
• Knowledge and experience with HIV testing;
• Knowledge and symptoms of other sexually transmitted infections (STIs); and
• Other health issues including knowledge of TB and medical injections.
Female respondents were asked about their birth history and illnesses of children they gave birth to since January 2002. These questions are used to gauge the prevalence of fever, an important symptom of malaria.
Table 1.1 shows response rates for the 2007-08 THMIS. A total of 9,144 households were selected for the sample, from both Mainland Tanzania and Zanzibar. Of these, 8,704 were found to be occupied at the time of the survey. A total of 8,497 households were successfully interviewed, yielding a response rate of 98 percent. In the interviewed households, 9,735 women were identified as eligible for the individual interview. Completed interviews were obtained for 9,343 women, yielding a response rate of 96 percent. Of the 7,935 eligible men identified, 6,975 were successfully interviewed (88 percent response rate). Table 1.1 shows that the response rates for men were lower than those for women. The differential is likely due to the more frequent and longer absence of men from the households. The response rates for urban and rural areas do not vary much. The table found in the report page 7.
Two questionnaires were used for the 2007-08 THMIS: the Household Questionnaire and the Individual Questionnaire. The questionnaires are based on the standard AIDS Indicator Survey and Malaria Indicator Survey questionnaires, adapted for the population and health issues relevant to Tanzania. Inputs were solicited from various stakeholders representing government ministries and agencies, non governmental organizations, and international partners. After the preparation of the definitive questionnaires in English, questionnaires were translated into Kiswahili.The Household Questionnaire was used to list all the usual members and visitors of selected households. Some basic information was collected on the characteristics of each person listed, including his or her age, sex, education, and relationship to the head of the household. For children under age 18 years, survival status of the parents was determined. If a child in the household had a parent who was sick for more than three consecutive months in the 12 months preceding the survey or a parent who had died, additional questions related to support for orphans and vulnerable children were asked. The Household Questionnaire also included questions on whether household members were seriously ill and whether anyone in the household had died in the past 12 months. In such cases, interviewers asked whether the household had received various kinds of care and support, such financial assistance, medical support, social or spiritual support.
The Household Questionnaire was also used to identify women and men who were eligible for the individual interview and HIV testing. The Household Questionnaire also collected information on characteristics of the household dwelling, such as source of water, type of toilet facilities, materials used to construct the house, ownership of various durable goods, and ownership and use of mosquito nets.
Furthermore, the Household Questionnaire was used to record haemoglobin and malaria testing results for children age 6-59 months.
The Individual Questionnaire was used to collect information from all women and men age 15-49. These respondents were asked questions on the following topics:
• Background characteristics (education, residential history, media exposure, employment, etc.);
• Marriage and sexual activity;
• Knowledge about HIV/AIDS and exposure to specific HIV-related mass media programmes;
• Attitudes towards people living with HIV/AIDS;
• Knowledge and experience with HIV testing;
• Knowledge and symptoms of other sexually transmitted infections (STIs); and
• Other health issues including knowledge of TB and medical injections.
Female respondents were asked about their birth history and illnesses of children they gave birth to since January 2002. These questions are used to gauge the prevalence of fever, an important symptom of malaria.
Start | End |
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2007-10-20 | 2008-02-22 |
Name | Affiliation |
---|---|
National Bureau of Statistics | Ministry of Finance and Economic Affairs |
Office of Chief Government Statician | Government of Zanzibar |
Data collection was carried out by 14 field teams, each consisting of one team leader, four female interviewers, one male interviewer, and one driver. Five senior staff members from NBS and OCGS-Zanzibar coordinated and supervised the fieldwork activities. Fieldwork on the Mainland started on 20 October 2007. Delay in obtaining ethical clearance for the Zanzibar fieldwork resulted in a delay in starting data collection in Zanzibar until 10 November 2007. Data collection took place over a four-month period, from 20 October 2007 to 22 February 2008. A quality control team periodically visited teams in the field to check their work and reinterview some households.
Data collection was carried out by 14 field teams, each consisting of one team leader, four female interviewers, one male interviewer, and one driver. Five senior staff members from NBS and OCGS-Zanzibar coordinated and supervised the fieldwork activities. Fieldwork on the Mainland started on 20 October 2007. Delay in obtaining ethical clearance for the Zanzibar fieldwork resulted in a delay in starting data collection in Zanzibar until 10 November 2007. Data collection took place over a four-month period, from 20 October 2007 to 22 February 2008. A quality control team periodically visited teams in the field to check their work and reinterview some households.
1.9 ANAEMIA, MALARIA, AND HIV TESTING
In addition to collecting information with the survey questionnaire, the THMIS also included anaemia and malaria testing for children under five (6-59 months) and HIV testing for adults age 15- 49. The protocol for the anaemia and HIV testing was based on the standard protocols employed in the MEASURE DHS project, adapted to achieve the objectives of the THMIS.
1.9.1 Anaemia Testing
In the THMIS, haemoglobin measurement for anaemia testing was performed in the field by a team member. Consent was obtained from the parent or guardian. The statement explained the purpose of the test, how the test would be administered, and advised the parent or guardian that the results would be available as soon as the test was completed. Finally, permission was requested for the test to be carried out. For haemoglobin measurement, capillary blood was usually taken from a finger of the children for whom consent had been obtained. A single-use, sterile lancet was used for this purpose. In cases where a child was very thin, a heel prick was used to obtain the sample.
The concentration of haemoglobin in the blood was measured using the HemoCue system. The results of the anaemia test were immediately provided for all eligible children tested. Levels of anaemia were classified as severe, moderate, or mild according to criteria developed by the World Health Organization (WHO). A brochure was provided on anaemia which included suggestions as to the steps (e.g., changes in diet) that could be taken in the event that a child was found to have some degree of anaemia. Parents/guardians of children who were found to be severely anaemic were advised to take the child to health facilities for further evaluation and management.
1.9.2 Malaria Testing
The rapid diagnostic test used in the 2007-08 THMIS is the Paracheck Pf™ device (Orchid Biomedical, India), which is based on the detection of P. falciparum-specific histidine-rich protein 2 (HRP2 Pf) in blood. The test has relatively high sensitivity and specificity and is deemed appropriate for clinical and epidemiologic assessment of malaria, especially placental malaria. Parents or responsible adults were advised about the malaria test result. If the child tested positive, he or she was provided with a full course of Artemether Lumefantrine (ALu or Coartem). Children who tested negative but had a fever in the past two weeks were also provided a full course of ALu. THMIS field staff explained to the parent or responsible adult that ALu is effective and should rid the child of fever and other symptoms in a few days. Parents/guardians were advised to take the child to a health professional for treatment immediately if, after taking ALu, the child still had high fever, fast or difficult breathing, was not able to drink or breastfeed, and became sicker or did not get better in two days.
1.9.3 HIV Testing
In the THMIS, HIV testing involved the collection of at least three blood spots from a finger prick on a special filter paper card. The testing was anonymous, i.e., it was conducted in such fashion that the results could not be linked to individual respondents. A unique random identification number (bar code) was assigned to each eligible respondent consenting to the testing. Labels containing the bar code were affixed to the filter paper card, the questionnaire, and a field tracking form at the time of the collection of the sample. No other identifiers were attached to the dried blood spot (DBS) sample. Because of the anonymous nature of the testing approach in the THMIS, it was not possible to provide information on the results from the HIV testing conducted during the THMIS.
The procedures that THMIS field staff followed to obtain informed consent from eligible individuals to collect DBS samples for the HIV testing were similar to those used for obtaining consent for the anaemia testing. The HIV testing consent statement explained the objective of the testing and how the DBS sample would be collected. Prospective subjects were informed that the testing process was anonymous and, therefore, their result would not be available to them, advised them of the availability of free voluntary counselling and testing services, and requested permission for the test to be carried out. Field staff also asked for consent to store the DBS samples for unspecified future tests.
After the survey team completed a cluster, all questionnaires, dried blood spot samples, and sample transmittal forms for the cluster were sent to the NBS for logging and checking prior to data entry. Blood samples were checked against the transmittal form and then forwarded to MUCHS Laboratory for testing. No identifying information other than the unique barcode label affixed at the time of the collection of the DBS sample accompanied the specimen to the laboratory
All questionnaires collected during the THMIS fieldwork were periodically brought from the field to the NBS headquarters in Dar es Salaam for processing, which consisted of office editing, coding of open-ended questions, data entry, and editing of computer-identified errors. The data were processed by a team of 9 data entry clerks, 2 data editors, and 2 data entry supervisors. An administrator was assigned to receive and check the blood samples coming from the field. Data entry and editing were accomplished using the CSPro software. All data were entered twice (100 percent verification). The concurrent processing of the data was a distinct advantage for data quality because THMIS staff were able to advise the field teams of errors detected during data entry. The process of office editing and data processing was initiated on 8 November 2007 and completed on 7 April 2008. Dried blood spot (DBS) samples received from the field were logged in at NBS, checked, and transported to MUCHS for testing. The processing of DBS samples for HIV testing at MUCHS was handled by six laboratory scientists. The DBS samples were logged into the CSPro HIV Test Tracking System database, each given a laboratory number, and stored at -20°C until tested
The estimates from a sample survey are affected by two types of errors: (1) nonsampling errors, and (2) sampling errors. Nonsampling errors are the results of mistakes made in implementing data collection and data processing, such as failure to locate and interview the correct household, misunderstanding of the questions on the part of either the interviewer or the respondent, and data entry errors. Although numerous efforts were made during the implementation of the 2007-08 Tanzania HIV/AIDS and Malaria Survey (THMIS) to minimize this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.
Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the 2007-08 THMIS is only one of many samples that could have been selected from the same population, using the same design and expected size. Each of these samples would yield results that differ somewhat from the results of the actual sample selected. Sampling errors are a measure of the variability between all possible samples. Although the degree of variability is not known exactly, it can be estimated from the survey results.
A sampling error is usually measured in terms of the standard error for a particular statistic (mean, percentage, etc.), which is the square root of the variance. The standard error can be used to calculate confidence intervals within which the true value for the population can reasonably be assumed to fall. For example, for any given statistic calculated from a sample survey, the value of that statistic will fall within a range of plus or minus two times the standard error of that statistic in 95 percent of all possible samples of identical size and design.
If the sample of respondents had been selected as a simple random sample, it would have been possible to use straightforward formulas for calculating sampling errors. However, the 2007-08 THMIS sample is the result of a multi-stage stratified design, and, consequently, it was necessary to use more complex formulae. The computer software used to calculate sampling errors for the 2007-08 THMIS is the ISSA Sampling Error Module. This module used the Taylor linearization method of variance estimation for survey estimates that are means or proportions. The Jackknife repeated replication method is used for variance estimation of more complex statistics such as fertility and mortality rates.
The Taylor linearization method treats any percentage or average as a ratio estimate, r = y/x, where y represents the total sample value for variable y, and x represents the total number of cases in the group or subgroup under consideration. The variance of r is computed using the formula given below, with the standard error being the square root of the variance, further information on sampling errors are available from page 173-214 appendix B of the Survey.
Name | Affiliation | URL | |
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National Bureau of Statistics | Ministry of Finance and Economic Affairs | www.nbs.go.tz | info@nbs.go.tz |
Is signing of a confidentiality declaration required? | Confidentiality declaration text |
---|---|
yes | Confidentiality of respodents is guaranteed by section 20 of Tanzania Statistics act number 1 of 2002 Before being granted access to the dataset, all users have formally agree: 1.all identifying information such as the name and address of respondent has been removed; and 2.the information is disclosed in a manner that is not likely to enable the identification of the particular person or undertaking or business to which it relates. 3.not attempt to identify any particular person or undertaking or business; 4.use of information for research or statistically purpose only; 5.not to disclose the information to any other person, organization 6.when required by the Director General, return all documents made available to him to the Director General; 7.comply with the directions given by the Director General relating to the records. 8.every person involved in the research or statistical project for which information is disclosed pursuant to this section shall make the declaration of secrecy set out in the first schedule. |
Tanzania NBS considered three levels of accessibility:
The dataset has been anonymized and available as a public use dataset. It accessible to all for statistical and research purposes only, under the following terms and conditions:
1.The data and other material will not be redistributed or sold to other individuals, institutions, or organization without the written agreement of the National Bureau of Statistics.
2.The data will be used for statistical and scientific research purposes only. They will be used solely for reporting of aggregated information, and not for investigation of specific individuals or organizations.
3.No attempt will be made to produce links among dataset provided by the National Bureau of Statistics, or among data from the (National Bureau of Statistics) and other datasets that could identify individuals or organizations
4.No attempt will be made to re-identify respondents, and no use will be made of the identify of any person or establishment discovered inadvertently. Any such discovery would immediately be reported to the National Bureau of Statistics.
5.Any books, articles, conference papers, theses, dissertations, reports, or other publications that employ data obtained from the National Bureau of Statistics will cite the source of data in accordance with the Citation Requirement provided with each dataset.
"National Bureau of Statistics, Tanzania HIV/AIDS and Malaria Indicator Survey 2007-2008(THMIS 2007-2008), version 1.0 of the public use dataset(November 2008) pvovided by the National Bureau of Statistics, www.nbs.go.tz"
"The user of the data should acknowledges that, National Bureau of Statistics is the original collector of the data , the authorised distributor of the data, and the relevant funding agency bear no responsibility for use of the data or for interpretations or inferences without a written agreement from the National Bureau of Statistics"
(c)National Bureau of Statistics
Name | Affiliation | URL | |
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Director General | National Bureau of Statistics | dg@nbs.go.tz | www.nbs.go.tz |
TZA-NBS-THMIS-2007-2008v01
Name | Affiliation | Role |
---|---|---|
National Bureau of Statistics | Ministry of Finance and Economic Affairs | Data Producer |
Office of Chief Government Statician Zanzibar | Government of Zanzibar | Data Producer |
Accelerated Data Program | PARIS21 | Review of the metadata |
2010-02-11
Version 1.0