One Health approach to measure the impact on wellbeing of selected infectious diseases in humans and animals in Zambia

This study describes the results of a cross-sectional survey conducted in Mambwe district in the Eastern Province in Zambia. It uses a One Health approach to assess the impact of veterinary, medical, environmental and social determinants on animal and human health and wellbeing. One Health is defined as a holistic and interdisciplinary approach that describes the complexities between people, animals, the environment and their health. Human wellbeing is defined in this thesis as ‘a condition in which all members of society are able to determine and meet their needs and have a large range of choices to meet their potential’ (Prescott-Allen, 2001). As a first step, eight focus group discussions with the inhabitants followed by key informant interviews with stakeholders in the area were conducted to give a primary impression and narrow down the problems in relation to animal and human health of the area in general. Following this, a randomized selection of 210 households was visited and in each household blood samples were taken from all humans and all animals belonging to five animal species, namely cattle, goats, sheep, pigs and dogs. A third of the households did not keep any of the animal species chosen for sampling, but their inclusion was important for the social analysis. In all of these 210 households a wellbeing questionnaire was administered and, for every human and animal sampled, a health questionnaire. The study area falls within the tsetse-infested region of Zambia. It has a high wildlife density reflecting the proximity of several national parks and is historically endemic for both human and animal African trypanosomiasis (HAT&AAT). Therefore humans and animals were tested for trypanosomiasis using internal transcribed spacer (ITS) polymerase chain reaction (PCR). Since it is important as a differential diagnosis, malaria was tested for by a rapid diagnostic test in the field from human blood. Sera from mature individuals from all animal species except pigs were tested in a field laboratory for brucellosis using the Rose Bengal test. Additionally, cattle and dogs were tested for five genera of tick-borne infections (TBI) including Anaplasma, Ehrlichia, Theileria, Babesia and Rickettsia using reverse line blot (RLB) in the laboratory at the University of Edinburgh (UoE). The blood samples for PCR and RLB analysis at UoE were stored on WhatmanTM FTA cards. A total of 1012 human samples were tested for HAT and none found positive. 1005 (seven people had been tested positive or treated against malaria shortly before the sampling) people tested for malaria showed an overall prevalence of 15% (95% CI 13.2-17.7). None of the 734 Rose Bengal tests showed up positive for brucellosis. The prevalence of AAT in 1275 samples tested was much lower compared to former samplings; in cattle 22% (95% CI 18-27.2), in goats 7% (95% CI 4.5-9.2), in pigs 6% (95% CI 3.2-9.4), in dogs 9% (95% CI 5.2-13.6) and no samples were found positive in sheep. The prevalence of TBIs is much more complex with many multiple infections. A total of 340 cattle and 195 dogs were tested. In cattle the number of samples positive for any microorganism was as follows; 92% (95% CI 88- 94.2). Overall there were fewer positive samples from dogs with 25% of animals infected (95% CI 19.2-31.8). The wellbeing and health questionnaires were designed to help to identify possible risk factors for the above-mentioned diseases and signs, such as fever, diarrhoea and seizures, indicative for several other diseases. The results of these surveys might also help to identify potential reasons for a lower or higher prevalence of trypanosomiasis and malaria found than expected from previous studies. Additionally, information on personal happiness, attitudes towards veterinary and medical services, medical treatments received, education, women’s reproductive history, drug abuse, people’s perceptions of changes in environment and agriculture, demography, poverty and migration were collected via the questionnaires alongside information on livestock demographics and fertility. One of the main conclusions is that both medical and veterinary health care systems suffer from a number of shortcomings. The distance to appropriate treatment and care facilities is far and the necessary drugs are often unavailable. Also, both the knowledge and technology for diagnosing selected diseases is not in place. This study suggests that neurocysticercosis (NCC) plays an important role in this area due to the high number of seizures reported in people, in whom treatment for epilepsy was unsuccessful. Samples taken from a few pigs indicated the presence of Taenia solium, the causal agent of NCC. Furthermore, many of the TBIs are of zoonotic nature and further investigations must be made to begin to assess the burden of these diseases in humans and animals. Environmental changes such as degradation of the vegetation are likely to have an influence on the prevalence of studied diseases and this aspect is being investigated further in other studies. Due to the nature of a cross-sectional study, only limited conclusions can be drawn on the causal relationships of disease prevalence, but the social analysis conducted in this study confirmed the interactions of selected factors related to health and wealth unique for this study area