Undercounting controversies in South African censuses

A thesis submitted to the Faculty of Humanities in fulfilment of the requirements of the degree of Doctor of Philosophy in Demography and Population Studies, University of Witwatersrand, Johannesburg, South Africa 2016Census taking dates back to the era of the Roman Empire as can be drawn from the gospel of Luke Chapter 2, Verses 1-5. Under the Roman rule censuses were conducted to keep records for individuals that were eligible for conscription into the army. Later during the colonial era, censuses were conducted to capture individuals that were eligible to pay tax. Currently censuses are widely used in guiding efficient planning and fair resource allocation. Content error, which refers to recording inaccurate information on captured individuals, and coverage error, i.e. either undercounting or over counting of people in a census, presents challenges in achieving these goals. Coverage error is frequent in censuses, especially undercount, which is of interest in this study. In countries that have a well-documented history of census taking like the United States of America, Canada, and China, there are indications that respective censuses recorded substantial numbers of people that were missed. Nigeria and South Africa are some of the countries in Africa where high undercounts have been recorded in censuses. The latter country, which is the focus of this study, recorded undercount estimates of 10.6%, 17%, and 14.6% in the last three censuses of 1996, 2001, and 2011 respectively. These high undercount estimates were the source of controversies that have been associated with the three censuses. The controversies centred on the accuracy of the Post-enumeration Survey (PES). Critiques argue that the PES has been inaccurate in estimating and adjusting the undercount in the respective censuses. For this reason, the accuracy of both the undercount estimates and adjusted counts drawn from this method has also been contested. [Abbreviated abstract. Open document to view full version]GR201

Epilepsy in sub-Sahran Africa : analysis of excess mortality in epilepsy and associated risk factors from cohort studies

Epilepsy is a disorder of the brain manifested with the recurrent unprovoked seizures. It affects about 71 million people globally. Epileptic seizures may involve a sudden loss of conscious, rapid muscles rigidity and contractions, violent convulsions and falls if a person is standing or sitting. Epilepsy can be controlled by antiepileptic drugs (AEDs) and adherence to treatment has been shown to improve quality of life, reduce seizure frequency, injuries, and death. Epileptic seizures negatively impact the lives of people with epilepsy (PWE) and those around them especially in LMIC. It is estimated that 80% of PWE live in LMICs. Excess mortality in PWE in developed countries is estimated to be up to 2 times higher than general population. There is scant data on excess mortality in PWE in SSA. Scarcity of evidence on the impact of epilepsy has resulted in PWE being marginalized in health services planning and provision despite having high psychological, economic, morbidity and mortality burden relative to the general population. This thesis provides needed knowledge on uncertainties of epilepsy in SSA in relation to mortality, risk factors, and causes of death in PWE. The knowledge and evidence were generated from five studies using empirical data from community-based studies. Systematic review The first thesis objective was aimed at reviewing and summarizing available evidence on excess mortality in PWE compared to general population in LMIC. Systematic review in Chapter 3 identified only 7 studies in LMIC over the period of 25 years. Estimated excess mortality of ranged from 1.3-7.2 times higher in PWE than general population (median=2.6). Meta-analysis of this systematic review indicated that up to 80% of total variability’s in the estimate of excess mortality (SMR) was only due to differences between studies. These differences may be due to methodological variations between studies or other unknown factors. The estimated excess mortality of 2.6 was median value and not pooled estimate as large variability’s between studies could not allow combined estimate of 7 studies. In conclusion, until this systematic review was done, there were no sufficient data to provide empirical evidence of excess mortality in PWE in LMIC. SEEDS study: Excess mortality At the time the systematic review was completed, new data on mortality of PWE were emerging from SEEDS studies. SEEDS studies had already followed PWE for over 8 years and documented deaths in people with and without epilepsy. Chapter 4 of this thesis was dedicated at pooling and generating new evidence of excess mortality in PWE from SEEDS studies. The pooled excess mortality was 4.8 times higher in PWE than general population (95% CI: 4.2-5.6). SEEDS estimate is higher than summary findings from systematic review in reported in the literature in Chapter 4. SEEDS studies were conducted to account for methodological limitations encountered in most epilepsy studies related to screening, diagnosis, mortality and causes of death assessment, and population representativeness. SEEDS study: Risk factors The studies also identified modifiable risk factors potential for intervention programs and mitigating the negative impact of epilepsy. Causes of death automation In addition to summarizing excess mortality in PWE, systematic review in Chapter 3 summarized causes of deaths in PWE from different studies. Summary estimates from different studies in LMIC indicated most PWE died of direct causes which are status epilepticus (SE) and sudden death in epilepsy (SUDEP) and indirect (injuries) causes of epilepsy death. These studies compiled causes of death information from variety of sources including physicians, verbal autopsies and death certificates. In Chapter 5, this thesis assessed the application of automated tools in ascertaining causes of death in PWE. The assessment indicated that, the use of automated tools is potentials, convenient and affordable alternative to post-mortem and physician death certification. Unlike the use of other sources of cause of death information, automated tool estimated lower number of epilepsy-related deaths (27.5%) compared to around 50% when physician make diagnosis of cause of death. Chapter 5 also provides valuable information and recommendation needed for further development and refinement of these tools especially with regards to coding SUDEP, SE, and injuries. National estimates Chapter 6 and 7 provides national and community-based estimates of mortality of epilepsy and other neurological disorders from national (SAVVY) and community-based studies (HDSS). The findings indicate epilepsy the second leading cause of death after cerebrovascular disorders. The estimates of mortality rate in the population ranged from 7-8 and 4-8 deaths per 100,000 populations in SAVVY and HDSS respectively. HDSS data HDSS sites have become platform for monitoring demographic indicators in most SSA. Analysis of HDSS data was aimed at ascertaining whether there has been declining trends in epilepsy and other neurological disorders over time. In Chapter 7 of this thesis, results of the analysis indicated epilepsy mortality did not change over the past 15 years. Synthesis This thesis generated new insights into the epidemiology of epilepsy in SSA. Limited data of studies of burden of epilepsy mortality in SSA point to either lack of interest in the subject, resources limitations from governments and funding bodies, and lack of knowledge of the negative impact of epilepsy. This study provides vigorous evidence of excess mortality needed for advocacy to health care providers, governments, and funding bodies for increased investment in care, preventions and reduction of the negative impact of epilepsy in SSA. The community and health care providers will benefit from evidence on modifiable risk factors for incidence and excess mortality from SEEDS study

Changes in mortality patterns and associated socioeconomic differentials in a rural South African setting: findings from population surveillance in Agincourt, 1993-2013

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy (by publications) 20th December 2017.Understanding a population’s mortality and disease patterns and their determinants is important for setting locally-relevant health and development priorities, identifying critical elements for strengthening of health systems, and determining the focus of health services and programmes. This thesis investigates changes in socioeconomic status (SES), cause composition of overall mortality and the socioeconomic patterning of mortality that occurred in a rural population in Agincourt, northeast South Africa over the period 1993-2013 using Health and Demographic Surveillance Systems (HDSS) data. It also assesses the feasibility of applying record linkage techniques to integrate data from HDSS and health facilities in order to enhance the utility of HDSS data for studying mortality and disease patterns and their determinants and implications in populations in resource-poor settings where vital registration systems are often weak. Results show a steady increase in the proportion of households that own assets associated with greater modern wealth and convergence towards the middle of the SES distribution over the period 2001-2013. However, improvements in SES were slower for poorer households and persistently varied by ethnicity with former Mozambican refugees being at a disadvantage. The population experienced steady and substantial increase in overall and communicable diseases related mortality from the mid-1990s to the mid-2000s, peaking around 2005-07 due to the HIV/AIDS epidemic. Overall mortality steadily declined afterwards following reduction in HIV/AIDS-related mortality due to the widespread introduction of free antiretroviral therapy (ART) available from public health facilities. By 2013, however, the cause of death distribution was yet to reach the levels it occupied in the early 1990s. Overall, the poorest individuals in the population experienced the highest mortality burden and HIV/AIDS and tuberculosis mortality persistently showed an inverse relation with SES throughout the period 2001-13. Although mortality from non-communicable diseases (NCDs) increased over time in both sexes and injuries were a prominent cause of death in males, neither of these causes of death showed consistent significant associations with household SES. A hybrid approach of deterministic followed by probabilistic record linkage, and the use of an extended set of conventional identifiers that included another household member’s first name yielded the best results for linking data from the Agincourt HDSS and health facilities with a sensitivity of 83.6% and a positive predictive value (PPV) of 95.1% for the best fully automated approach. In general, the findings highlight the need to identify the chronically poorest individuals and target them with interventions that can improve their SES and take them out of the vicious circle of poverty. The results also highlight the need for integrated health-care planning and programme delivery strategies to increase access to and uptake of HIV testing, linkage to care and ART, and prevention and treatment of NCDs especially among the poorest individuals to reduce the inequalities in cause-specific and overall mortality. The findings also contribute to the evidence base to inform further refinement and advancement of the health and epidemiological transition theory. Furthermore, the findings demonstrate the feasibility of linking HDSS data with data from health facilities which would facilitate population-based investigations on the e↵ect of socioeconomic disparities in the utilisation of healthcare services on mortality risk. Keywords Agincourt Cause of death composition Epidemiological Transition Health and Demographic Surveillance System (HDSS) Household assets HIV/AIDS Index of Inequality InterVA Mortality Non-communicable Diseases Population Surveillance Record linkage Rural Socioeconomic Status South Africa Verbal Autopsy Wealth IndexLG201

Identifying, characterizing, and targeting the reservoir of malaria transmission in Southern Tanzania.

Malaria continues to be a leading cause of morbidity and mortality in countries where it is endemic. While dramatic progress has been achieved globally, recent global malaria reports suggested that overall global progress has stalled since 2014. The plateau in improvement, particularly in high transmission settings of Africa, is associated with several factors, including inadequate coverage and use of the interventions, poor health service coverage, changes in vectors bionomics and insecticides resistance to malaria vectors. In addition, many high transmission countries have insufficient community based interventions to reduce malaria morbidity and mortality. Barriers to progress are associated with uncoordinated surveillance systems, low socioeconomic and living standards as well as inadequate adherence of the affected population to interventions. This hinders the efforts to achieve the overall goal of malaria elimination in many malaria endemic settings, highlighting the need for overall health system improvement to allow for innovative control and surveillance techniques. Furthermore, it necessitates a better understanding of malaria transmission dynamics. In order to meet this challenge, we must delve deeper into the underlying malaria transmission dynamics. The proposed PhD project was embedded within a tripartite pilot project between China-United Kingdom-Tanzania. The project was about Malaria control in Rufiji district, Tanzania, that started in September 2015. The overarching goal of the PhD project was to study the dynamics of malaria transmission and evaluate the impact of community-based malaria reactive case detection strategy in strengthening the transmission-reduction of human malaria infections in areas with high coverage of LLINs. To achieve the project's goal, four specific objectives were specified. This matches to the project chapters' conclusions in this thesis. In Chapter three of this thesis, the effectiveness of implementing a community-based testing and treatment plan to reduce the malaria burden in moderate to high transmission areas is analyzed. The "1-3-7" surveillance and response model developed in China, which prompted the development of this initiative and subsequent adoption of the 1,7-malaria Reactive Community-based Testing and Response (1,7mRCTR) approach, is a novel method for implementing the WHO-T3 and surveillance intervention to eliminate malaria. However, the 1-3-7 model is more effective in China, where the goal is to eradicate the disease, than in Tanzania, where the bulk of the population still has moderate to high transmission. The 1,7-mRCTR is locally-tailored for reporting malaria cases on day one and intervention on day seven, with community-based testing and treatment in high-burden areas stratified based on weekly data from health facilities. In the same district, control areas with comparable epidemiology (no 1,7-mRCTR) were selected and monitored for the duration of the project. After two years of implementing the 1.7 mRCTR, the prevalence of parasites in the target areas was reduced by 66 percent above and above the benefit provided by national measures already in place. Despite the fact that new technology and techniques may be required to eradicate malaria in stable transmission areas of Sub-Saharan Africa, this experiment proved that a locally tailored approach could help to expedite malaria control and elimination efforts. In addition, it highlight the opportunities of validating the results and possibilities of scaling up 1,7-mRCTR approach in other settings within Tanzania, and other African countries for accelerating malaria control and elimination across Africa. In chapter four of this dissertation, the household cross-sectional survey data gathered prior to 1,7-mRCTR intervention were used to describe and characterize the malaria prevalence and the associated exposures risk . In the context of the Tanzania Demographic and Health Survey and Malaria Indicator Survey (TDHS-MIS) 2015-16, this study’s findings are discussed. The findings highlight the importance of national malaria monitoring, and its ramifications for present malaria management strategies. The prevalence of malaria varied by ward, ranging from 5.6 percent to 18 percent, with the average prevalence reported by this study (13 percent) being higher than the reported by the RDHS-MIS national (7.3 percent). Based on the findings of this chapter, t is important for the new malaria control plans to be effective in sustaining gains and accelerating progress towards the end goals in the fight against malaria will depend on clearing parasitaemia and ensuring that poverty is eleviated Importantly, programs intended to improve malaria interventions for the currently recognized vulnerable groups should be modified to include other groups observed with highest parasitaemia. Chapter five investigated and assessed one of the extremely sensitive epidemiological study of malaria transmission (host preference by malaria vectors). In addition to being a significant predictor of malaria transmission patterns, this indicator is essential for determining the appropriateness and efficacy of vector control interventions and for predicting malaria transmission patterns. Using the direct host-preference experiment, the host preference of the primary malaria vector species, Anopheles arabiensis and Anopheles gambiae sensu stricto, was examined in two distinct ecological contexts in Tanzania. In contrast to historical accounts, the data indicate that urban An. arabiensis showed a stronger preference for cattle than rural An. arabiensis, but An. gambiae showed no preference for either people or animals under the same conditions. To achieve malaria eradication, we must have a deeper understanding of the prevalent vectors, their feeding behavior in varied ecological situations, and their feeding preferences. This will allow us to more effectively design and implement locally-tailored, high-impact, integrated interventions. Anopheles mosquito species composition, abundance, and spatial-temporal variability must be thoroughly understood in order to optimally exploit high-resolution malaria vector control strategies. Community-based mapping of residual malaria vector densities to support malaria elimination efforts in southeastern Tanzania is discussed in Chapter six. The findings highligth the changing composition of vector species through time, as well as the presence of many malaria vector species at the village scale, which is characterized by a wide spectrum of ecological variation. Human biting rates (HBR) in the study wards ranged from 1.5 to 73 bites per person every night. Characterization of Anopheles vectors indicated disparities between villages and wards in the distribution of Anopheles gambiae s.l., Anopheles funestus, and Anopheles coustani. This study's findings give evidence-based information that is essential for planning and implementing vector control actions in a local setting, complementing the results of Chapter four. In addition, the findings highlight the significance of comprehending and incorporating vector bionomics data into surveillance and response systems in order to successfully implement the ongoing micro-stratification of malaria strata. Surveillance is acknowledged as an intervention and considered instrumental in accelerating global malaria elimination efforts. However, all available evidence to date supports the incorporation of surveillance as in intervention in low endemicity areas, with no evidence comes from moderate to high endemicity areas. Therefore, this PhD project is the first attempt to develop a surveillance and response strategy in moderate to high transmission setting. The findings aline the current Tanzania mid-term review of the national malaria control as well as with the goals Global Technical Strategy 2015-2030 (GTS) and the High Burden to High Impact (HBHI) initiative, which both reiterated the importance of tailoring intervention approaches to the sub-national local context in order to accelerate progress toward malaria reduction and elimination. Behaviour ecology matters and so does evolutionary biology in human-modified environment, the spatial-temporal variation findings in vector composition at a fine scale level of village and the reduced human-biting preference of the primary malaria vectors collected from two distinct characterized with different ecological features is an example illustrating why regular surveys of mosquito compositions and behaviour need to be incorporated in malaria surveillance. Furthermore, support that, in regions with a high malaria incidence, the convention interventions should be maintained, while prioritizing taiolored approach based on the local contex

Rotavirus Diarrhea Among Young Children Before Introduction of the Rotavirus Vaccine Program in Kenya : Baseline Data and Implications for Vaccine Safety Monitoring and Impact Evaluation

Ripulitaudit ovat toiseksi yleisin alle viisivuotiaiden lasten kuolinsyy maailmanlaajuisesti. Rotavirus on tärkein lasten vakavien, kuivumista aiheuttavien ripulitautien aiheuttajista ja merkittävä kansanterveysongelma etenkin matalan ja keskitulotason maissa. Rotavirusrokotukset aloitettiin Kenian kansallisessa rokotusohjelmassa heinäkuussa 2014 (kaksi annosta, kuuden ja kymmenen viikon ikäisenä). Rotaviruksen aiheuttaman tautitaakan perustason määrittäminen paikallisesti ennen rokotusten aloittamista on välttämätöntä, jotta rokotusohjelman vaikuttavuutta väestötasolla voidaan jatkotutkimuksissa arvioida. Tämän väitöskirjatyön tavoitteena oli arvioida kattavasti alle viisivuotiaiden lasten ripulitaudin ja rotaviruksen aiheuttamaa tautitaakkaa, hoitoon hakeutumista ja komplikaatioita ennen rotavirusrokotusten aloitusta Keniassa. Väitöskirjan tutkimuksissa käytettiin Kenian lääketieteellisen tutkimuslaitoksen (Kenya Medical Research Institute, KEMRI) ja USA:n tautikeskuksen (Centers for Disease Control and Prevention, CDC) länsi-Keniassa sijaitsevan väestöpohjaisen, aktiivisen seurantajärjestelmän tietoja. Näiden tietojen perusteella määritettiin hoitoon hakeutumisen syyt ja yleisyys, taudin ilmaantuvuus ja riskitekijät, sekä sairaalahoidot ja kuolleisuus. Lisäksi vakavan ripulitaudin aiheuttamien komplikaatioiden (suolentukkeuma - intussusception) esiintyvyyttä ja ennusteeseen vaikuttavia tekijöitä arvioitiin takautuvasti sairaalojen potilaskertomustietojen avulla. Tutkimusten tavoitteena oli muodostaa kattava kuva rotavirustaudin epidemiologiasta, jota voidaan jatkotutkimuksissa käyttää vertailukohtana arvioitaessa rotavirusrokotusohjelman kansanterveydellistä vaikuttavuutta Keniassa. Väitöskirja koostuu neljästä alkuperäistutkimuksesta (I-IV). Väestöpohjaisessa kenttätutkimuksessa (I) haastateltiin ensin 1 043 alle viiden vuoden ikäisen lapsen huoltajaa (yleensä äitiä) poikkileikkaustutkimuksessa (huhti–toukokuu 2007) lasten ripulitauteihin liittyvän hoitoon hakeutumisen käytäntöjen määrittämiseksi (ripulin määritelma ≥ 3 loysaa ulostetta 24 tunnin aikana). Taman jalkeen yli 20 000:n lapsen huoltajia haastateltiin viidessä peräkkäisessä poikkileikkaustutkimuksessa toukokuun 2009 ja joulukuun 2010 välisenä aikana. Tutkimuksessa (II) tunnistettiin sairaalahoitoon tulleet potilaat, joilla oli äkillinen ripulitauti (akuutti gastroenteriitti, AGE) - potilaalla ripuli ja/tai yksi/useampi selittämätön oksenteluepisodi seitsemän päivän sisällä sairaalaan tulosta. Tutkimuksessa määritettiin sairaalahoitoa vaativan akuutin gastroenteriitin sekä rotaviruksen aiheuttaman gastroenteriitin (RVAGE) ilmaantuvuudet ja niihin liittyvä kuolleisuus. Nimittäjätiedot saatiin länsi-Kenian terveys- ja demografiatietojen seurantajärjestelmästä (HDSS). Sairaalapohjaisessa tutkimuksessa (III) selvitettiin rotaviruksen aiheuttaman ripulitaudin riskitekijöitä ja taudinkuvan vakavuutta. Seurannassa tunnistettiin sairaalahoitoon tulleet lapset, joilla oli akuutti, ei-verinen kohtalaisen vakava tai vakava ripulitauti (MSD). Rotavirus taudinaiheuttajana tunnistettiin tutkimuksiin II ja III osallistuneiden lasten ulosteenäytteistä EIA-määrityksellä. Takautuvassa tutkimuksessa (IV) selvitettiin potilaskertomustietojen avulla suolentukkeumaan liittyviä tekijöitä ja tapauskuolleisuutta alle viiden vuoden ikäisillä potilailla, joilla oli diagnosoitu suolentukkeuma 12 Kenialaisessa keskussairaalassa vuosina 2002-2013. Väestöpohjainen ripulin ilmaantuvuusosuus kahden viikon aikana vaihteli ensimmäisen seurantavuoden (2007) 26%:sta 4–11%:iin vuosina 2009–2010. Alle puolet ripulitautia sairastavista lapsista hoidettiin terveydenhuollon yksiköissä. Huoltajat veivät imeväisikäisiä lapsiaan hoitoon kodin ulkopuolelle merkitsevästi harvemmin kuin vanhempia lapsia. Hoitoon vieminen kodin ulkopuolelle oli kuitenkin yleisempää niillä lapsilla, joiden silmät olivat painuneet sisään kuivumisen takia ripulijakson aikana. Merkittävälle osalle sairaista lapsista annettiin myös vähemmän nestettä ja ruokaa kuin normaalisti, eikä heille tarjottu nestelisää suun kautta (oral rehydration solution - ORS) kotona. Koulutetut äidit antoivat kuitenkin useammin lapsilleen kotona ORS nestettä ja veivät heidät hoitoon terveydenhuollon yksikköön kuin kouluttamattomat äidit. Akuuttia gastroenteriittiä ja rotavirusripulitautia sairastavien lasten joutuminen sairaalahoitoon oli yleisintä 6– 11 kuukauden iässä. Myös kuolleisuus oli suurin tässä ikäryhmässä. Rotaviruspositiiviset potilaat olivat nuorempia (mediaani-ikä, 8 vs. 13 kuukautta), heillä oli vakavampi tauti ja he joutuivat sairaalahoitoon merkitsevästi useammin kuin ne potilaat, joiden ulosteviljely oli negatiivinen rotaviruksen suhteen. Rotavirusripulin itsenäisiä riskitekijöitä olivat imeväisikä ja runsas oksentelu. Kahdessatoista Kenialaisessa sairaalassa vuosina 2002-2013 hoidetuista suolentukkeumapotilaista kaksi kolmasosaa oli vauvoja, joilla oli ainakin yksi seuraavista oireista: oksentelu, ripuli tai verta ulosteessa. Suolentukkeuman tapauskuolleisuus oli 6,4%. Verrattuna potilaisiin, jotka toipuivat, menehtyneet potilaat olivat nuorempia, heillä oli kuumetta ja he tulivat hoitoon myöhemmin oireiden puhkeamisen jälkeen. Heitä oli myös hoidettu kirurgisesti useammin kuin taudista selviytyneitä. Yhteenvetona tämän tutkielman tutkimukset osoittavat, että lasten akuutti ripulitauti ja etenkin rotaviruksen aiheuttama vaikeaoireinen ripuli ovat merkittävä kansanterveysongelma Kenialaisten pikkulasten keskuudessa. Terveydenhuollon piiriin tulevat tautitapaukset ovat kuitenkin vain jäävuoren huippu. Siksi on huolestuttavaa, että monien lasten huoltajat viivyttivät hoitoon hakeutumista ripuliepisodin alettua ja jopa vähensivät nesteen ja ruoan antamista. Myös suolentukkeumaan kuolleiden potilaiden hoitoon hakeutuminen oireiden alkamisen jälkeen oli viivästynyt. Tutkimukset vahvistivat gastroenteriitin, rotavirusripuliin ja suolentukkeumaan liittyvän sairastuvuuden ja kuolleisuuden olevan yleisintä imeväisiässä. Tulokset tukivat Kenian terveysministeriön päätöstä aloittaa rotavirusrokotusohjelma heinäkuussa 2014. Ne ovat myös linjassa Maailman Terveysjärjestön (WHO) suosituksen kanssa, jonka mukaan rotavirusrokotteet tulee antaa kuuden ja kymmenen viikon ikäisenä. Näin lapset saavat rokotteet ennen kuin taudin ilmaantuvuus on Keniassa huipussaan. Kokonaisuutena väitöskirjan tutkimusten tulokset muodostavat kattavan perustason, johon vertaamalla Kenian rotavirusrokotusohjelman väestötason vaikuttavuutta rotavirustaudin esiintyvyyteen, riskitekijöihin ja komplikaatioiden yleisyyteen voidaan jatkotutkimuksissa täsmällisesti arvioida. Tutkimusten perusteella arvioinneissa ja ehkäisyohjelmissa on erityisesti otettava huomioon havainnot vakavasti sairastuneiden lasten huoltajien terveydenhuoltoon hakeutumisen käytännöistä ja hoidon viivästymisestä. Jatkuva väestöpohjainen seuranta on avainasemassa rotavirusrokotusohjelman kansanterveydellisen vaikuttavuuden osoittamiseksi Keniassa.Diarrheal diseases are the second leading cause of childhood deaths globally. Rotavirus is a leading cause of severe dehydrating diarrhea which is particularly associated with morbidity and mortality among children under five years of age in low- and middle-income countries. The rotavirus vaccine was introduced into Kenya’s public immunization program in July 2014, with a two-dose schedule at six and ten weeks of age. Estimating the burden of rotavirus-associated disease before vaccine introduction is essential for assessing the population-level impact of vaccination programs. The aim of this dissertation is to estimate the burden of diarrheal illness among children under five years of age before the introduction of rotavirus vaccine in Kenya and to provide baseline information on health care seeking, prevalence, hospitalizations, and potential complications of childhood diarrhea to help evaluate the impact of rotavirus vaccine program implementation in Kenya. This dissertation consists of four original studies. In Study I, we conducted household interviews with caretakers of 1,043 children under five in a baseline cross-sectional survey (April–May 2007) and of more than 20,000 children on five subsequent surveys between May 2009 and December 2010 to assess healthcare- seeking patterns for childhood diarrhea (defined as 2 ≥ 3 loose stools in 24 hours). In Study II, we conducted inpatient surveillance of children with acute gastroenteritis (AGE) (diarrhea and/or one or more episodes of unexplained vomiting occurring within seven days of admission) to estimate hospitalization and mortality rates due to all-cause and rotavirus acute gastroenteritis (RVAGE). Person-years of observation from an active Health and Demographic Surveillance System (HDSS) in western Kenya were used as denominators. In Study III, we conducted hospital-based surveillance of children under five years with acute, nondysenteric moderate-to-severe diarrhea (MSD) to assess factors associated with rotavirus gastroenteritis and to describe illness severity. We defined non-dysenteric MSD as diarrhea with one or more of the following: sunken eyes, skin tenting, intravenous rehydration, or hospitalization, and acute to mean seeking care for the diarrhea episode within seven days of illness onset at a study sentinel health center located within the HDSS. Stool specimens from participants enrolled in Studies II and III were tested for rotavirus using an enzyme immunoassay. To describe the epidemiology and risk factors for intussusception-related mortality, we retrospectively reviewed medical chart data of patients under five years old diagnosed with intussusception in 12 Kenyan leading referral hospitals (Study IV). Our results showed that the two-week population-based incidence proportion of any diarrhea during the study period ranged from 26% at baseline (2007) to 4– 11% during 2009–2010. A key finding of the surveys was that less than half of the children with diarrheal illness received care at a healthcare facility. Caretakers were actually less likely to seek health care outside the home for infants with diarrhea than for older children. Seeking care outside the home for childhood diarrhea was significantly more common for children who had sunken eyes during their diarrheal episode. Substantial proportion of children with diarrhea were given less food and drink than normally, even when vomiting accompanied their diarrheal episode. They were also not offered oral rehydration solution (ORS) at home. Mothers with formal education, however, were more likely than those without formal education to provide their children with ORS at home and to take them to a health care facility. Furthermore, caretakers sought care from a healthcare facility when their child`s diarrheal illness became more severe— possibly as a consequence of giving no remedy at home. Infants 6–11 months had the highest population-based incidence rates for hospitalization and mortality due to AGE and RVAGE. Rotavirus-positive cases were younger (median age, 8 vs. 13 months), had more severe illness, and had to be hospitalized more frequently than those who were negative for rotavirus. Independent factors that were associated with rotavirus disease included being an infant and presenting with vomiting 3 or more times within 24 hours during the diarrhea episode. Two-thirds of intussusception cases treated from 2002 through 2013 were infants who presented with at least one of the following symptoms: vomiting, diarrhea, or blood in stool. The case-fatality proportion was 6.4%. Compared with patients who survived, patients who died were younger, more likely to seek care late after illness symptom onset, to report history of fever on admission or, to have undergone surgery. In summary, the studies in this thesis demonstrate that diarrhea among young children presenting to health care facilities is a significant public health problem in Kenya. However, the cases attending health care facility are only the tip of an iceberg. Our findings that suggest delay in seeking care for the child`s severe diarrheal illness are disconcerting. In addition, among children with severe disease symptoms and intussusception patients who died had sought care later after symptom onset than those who survived. Our data also confirmed that morbidity and mortality associated with AGE, RVAGE, and intussusception was most common among infants. These findings supported the Kenyan Ministry of Health’s decision to introduce a rotavirus vaccination program in July 2014. They are also consistent with the WHO recommendation to administer rotavirus vaccines to children at six and ten weeks of age, before the peak of disease incidence in Kenya. As a whole, the results of this thesis provide a comprehensive baseline data on occurrence, risk factors and complications of rotavirus diarrhea among young children in Kenya against which the population-level vaccine program impact can be evaluated in the future. Continuing surveillance efforts aimed at demonstrating the real-world impact and value of rotavirus vaccines need to take into consideration the observed trends in health care utilization

Spatial and population drivers of persistent cholera transmission in rural Bangladesh: Implications for vaccine and intervention targeting

We identify high risk clusters and measure their persistence in time and analyze spatial and population drivers of small area incidence over time. The geographically linked population and cholera surveillance data in Matlab, Bangladesh for a 10-year period were used. Individual level data were aggregated by local 250 × 250 m communities. A retrospective space-time scan statistic was applied to detect high risk clusters. Generalized estimating equations were used to identify risk factors for cholera. We identified 10 high risk clusters, the largest of which was in the southern part of the study area where a smaller river flows into a large river. There is persistence of local spatial patterns of cholera and the patterns are related to both the population composition and ongoing spatial diffusion from nearby areas over time. This information suggests that targeting interventions to high risk areas would help eliminate locally persistent endemic areas

A cohort study of feeding patterns and health outcomes of infants in the Rufiji district of Tanzania

A mother-infant pair cohort study with 1302 participants was undertaken in the Rufiji district of rural Tanzania. Almost all infants (99%) were breastfed but only 2% were exclusively breastfed until six months of age. Lower maternal and paternal education levels, the use of pre-lacteal feeds, religion and maternal ownership of a radio were associated with exclusive breastfeeding. There was no statistical significant difference in growth and infection rates between exclusively and non-exclusively breastfed infants

L’état de santé perçu et les incapacités en Afrique subsaharienne : différences socioéconomiques et de genre

Bien que la relation entre l’état de santé perçu et les mesures de santé physique et mentale soit bien documentée dans les pays développés, très peu d’études ont examiné cette association dans le monde en développement, particulièrement en Afrique subsaharienne. De même, les études menées dans divers contextes sociaux ont documenté que les femmes et les personnes de plus faible statut socioéconomique (SSÉ) sont les plus susceptibles de porter un lourd fardeau des incapacités et de la mauvaise santé perçue, mais il n’est pas connu si ces associations existent aussi dans les pays africains. L'objectif général de cette recherche doctorale était d’aboutir à une meilleure compréhension de la stratification sociale de la santé en Afrique subsaharienne. Plus spécifiquement, cette étude visait à: 1) Examiner les associations entre la santé perçue et les mesures de santé physique et mentale (maladies chroniques, incapacités et dépression) parmi les adultes à Ouagadougou, Burkina Faso, et évaluer comment ces associations varient selon le sexe, le niveau d’éducation et l'âge; 2) Analyser les différences en matière d’incapacité cognitive et physique entre les hommes et les femmes âgés de 50 ans et plus à Ouagadougou et évaluer la mesure dans laquelle les différences observées pourraient être attribuables aux inégalités de genre en matière de conditions sociales et de santé à travers le cycle de vie; 3) Examiner la relation entre le SSÉ et une multitude de mesures d’incapacités parmi les adultes âgés de 18 ans et plus dans 18 pays d’Afrique subsaharienne et déterminer si les différences socioéconomiques dans les incapacités sont caractérisées par une divergence, convergence ou stabilité à travers l’âge. Les résultats de nos analyses sont présentés sous forme de trois articles scientifiques, qui se sont appuyés sur les données de l'Enquête santé réalisée en 2010 dans l'Observatoire de Population de Ouagadougou (OPO) et de la World Health Survey réalisée en 2002-2004 par l’OMS. Dans le premier article, nous avons trouvé que la mauvaise santé perçue était fortement associée aux maladies chroniques et aux incapacités, mais pas à la dépression. L’effet des incapacités sur la mauvaise santé perçue s’intensifiait avec l’âge et avec la diminution du niveau d’éducation. Par contre, l’effet des maladies chroniques semblait diminuer avec l’âge. Aucune variation selon le sexe n’était observée dans les associations de la santé perçue avec les maladies chroniques, les incapacités et la dépression. Ces résultats suggèrent que les différentes sous-populations définies selon le niveau d'éducation et l'âge pondèrent différemment les composantes de santé dans la santé perçue à Ouagadougou. Les résultats du second article indiquaient que le genre féminin était positivement associé à des niveaux plus élevés de détérioration cognitive et de mobilité réduite. L'excès des femmes dans ces incapacités était seulement partiellement expliqué par les inégalités de genre dans l’état nutritionnel, le statut matrimonial et, dans une moindre mesure, l'éducation. Ces résultats suggèrent que l’amélioration de l'état nutritionnel et des opportunités d'éducation à travers le cycle de vie pourrait prévenir la détérioration cognitive et la mobilité réduite et réduire partiellement l'excès féminin dans ces incapacités. Dans le troisième article, nous avons montré que le manque d'éducation était positivement associé à des niveaux plus élevés d'incapacités, et le différentiel d’état de santé fonctionnel entre les différents niveaux d'éducation restait stable à travers l'âge. Ces résultats suggèrent qu’en Afrique subsaharienne, comparativement aux individus hautement éduqués, les personnes faiblement éduquées ont moins de ressources économiques et sociales et de saines habitudes de vie qui ont des effets bénéfiques, constants sur la santé fonctionnelle selon l’âge.Although the relationship between self-rated health (SRH) and physical and mental health is well documented in developed countries, very few studies have analyzed this association in the developing world, particularly in sub-Saharan Africa. Furthermore, research in various social contexts has documented that disability and poor SRH are more common among women and persons with lower socioeconomic status (SES), but it is unclear whether these associations also hold in sub-Saharan African settings. The general objective of the present thesis was to better understand the social stratification in health in sub-Saharan Africa. More specifically, this study aimed to: 1) To examine the associations of SRH with measures of physical and mental health (chronic diseases, functional limitations, and depression) among adults in Ouagadougou, Burkina Faso, and how these associations vary by sex, education level, and age; 2) To analyze differences in cognitive impairment and mobility disability between older men and women in Ouagadougou, Burkina Faso, and to assess the extent to which these differences could be attributable to gender inequalities in life course social and health conditions; 3) To examine the relationship between SES and multiple disability measures among adults aged 18 and older in 18 sub-Saharan African countries and to determine whether socioeconomic differences in disability are characterized by an increase, decrease or stability with increasing age. The results of our analyses are in three scientific research articles, which rest upon data taken from a cross-sectional interviewer-administered health survey conducted in 2010 in areas of the Ouagadougou Health and Demographic Surveillance System, and the World Health Survey conducted in 2002-2004 by the World Health Organization (WHO). In the first article, poor SRH was strongly associated with chronic diseases and functional limitations, but not with depression. The effect of functional limitations on poor SRH intensified with age and with decreasing education level. In contrast, the effect of chronic diseases appeared to decrease with age. No variation by sex was observed in the associations of SRH with chronic diseases, functional limitations, and depression. These findings suggest that different subpopulations delineated by age and education level weight the components of health differently in their self-rated health in Ouagadougou. The results of the second article indicated that female gender was positively associated with higher levels of cognitive impairment and mobility disability. The female excess in these disabilities was only partially explained by gender differences in nutritional status, marital status and, to a lesser extent, education. These results suggest that enhancing nutritional status and educational opportunities throughout life span could prevent cognitive impairment and mobility disability and partly reduce the female excess in these disabilities. In the third article, we found that the lack of education was positively associated with poorer functional health, and the health gap between educational levels remains static with increasing age. These findings suggest that, in sub-Saharan Africa, compared to the well educated, the undereducated have fewer economic and social resources and health-promoting behaviors which have beneficial, albeit constant effects on functional health over the life course