Survey ID Number
TZA-NBS-HMIS-2007-v01
Title
Tanzania HIV/AIDS and Malaria Indicator Survey 2007-2008
Sampling Procedure
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.
Data Collection Notes
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