Christine Jost

Using participatory epidemiological techniques to estimate the relative incidence and impact on livelihoods of livestock diseases amongst nomadic pastoralists in Turkana South District, Kenya.

A participatory epidemiological (PE) study was carried out with Turkana pastoralists in Turkana South District, Kenya, to determine the relative incidence of livestock diseases and their impact on livelihoods. A sub-location was used as the sampling unit. A sub-location is the smallest administrative unit and is occupied by clusters of families (called adakars) that share common grazing patterns. A total of 32 sub-locations were randomly selected for the study. At least one focus group discussion involving more than 10 people was held with each adakar. In addition, key informant interviews involving local leaders and animal health service providers were conducted before or after the group sessions. PE techniques that were used with the stock owners include participatory mapping, relative incidence scoring, proportional piling, disease impact matrix scoring, seasonal calendars and probing. The methods used were pre-tested in four sub-locations that were excluded from further study. The study revealed that goats, with median score of 33 (10th and 90th percentiles of 25, 44, respectively) and sheep, median score of 20.5 (15, 26) were perceived to be the most abundant livestock species while goats (median score of 32 [21, 56]) and camels (median score of 22.5 [11, 33]) contributed the most to the livelihoods of the pastoralists. For goats, the overall relative incidence scores of peste des petits ruminants (PPR), contagious caprine pleuropneumonia (CCPP) and mange were 23.5% (15, 34), 25% (21, 45) and 20% (19, 28), respectively. The respective median scores for case fatality rates were 66% (45, 76.5), 62.5% (25, 100) and 73.2% (21.4, 85.7). Disease impact matrix scores indicated that mange was the most important disease of goats. Mange (range: 28-32%) and pox (range: 16-38%) were perceived to be the most prevalent diseases in camels. Livestock movements, limited access to veterinary services and stock theft were identified as key factors that contributed to the high prevalence and persistence of these diseases. This paper discusses strategies that could be used to control these diseases given the challenges associated with nomadic pastoralism and insecurity.

Human and porcine Taenia solium infections in Mozambique: Identifying research priorities.

Abstract The objective of this paper is to critically review and summarize available scientific and lay literature, and ongoing studies on human and porcine cysticercosis in Mozambique to identify knowledge gaps and direct immediate and long-term research efforts. Data on the spatial distribution and prevalence of the disease in human and swine populations are scarce and fragmented. Human serological studies have shown that 15–21% of apparently healthy adults were positive for cysticercosis antibodies or antigen, while in neuropsychiatric patients seroprevalence was as high as 51%. Slaughterhouse records indicate a countrywide occurrence of porcine cysticercosis, while studies have shown that 10–35% of pigs tested were seropositive for cysticercosis antibodies or antigen. Current research in Mozambique includes studies on the epidemiology, molecular biology, diagnosis and control of the disease. Future research efforts should be directed at better understanding the epidemiology of the disease in Mozambique, particularly risk factors for its occurrence and spread in human and swine populations, documenting the socio-economic impact of the disease, identifying critical control points and evaluating the feasibility and epidemiological impact of control measures and development of local level diagnostic tools for use in humans and swine.

Experiences in Participatory Surveillance and Community-based Reporting Systems for H5N1 Highly Pathogenic Avian Influenza: A Case Study Approach

Participatory surveillance (PS) is the application of participatory rural appraisal methods to the collection of epidemiological information to inform decision-making and action. It was applied in Africa and Asia as part of emergency programs to address the H5N1 highly pathogenic avian influenza (HPAI) pandemic. The approach resulted in markedly increased case detection in countries experiencing HPAI, and a better understanding of the epidemiological situation. Where HPAI was absent and PS was implemented, the method did not result in false positives and contributed to the overall epidemiological assessment that the country was free of disease. It was noted that clarity of surveillance objectives and resulting data needs at the outset was essential to optimize the balance of surveillance methods, size of the program and costs. The quality of training programs and adherence to international guidelines on good PS training practice were important for assuring the competence of PS practitioners. Orientation of senior decision-makers was an important step in assuring effective program management and appropriate use of results. As a problem-solving methodology, PS is best used to rapidly assess situations and inform strategy. Several countries continued PS after the end of projects and went on to apply PS to other health challenges.

The Effectiveness of Preventative Mass Vaccination Regimes Against the Incidence of Highly Pathogenic Avian Influenza on Java Island, Indonesia

We conducted an operational research study involving backyard and semicommercial farms on Java Island, Indonesia, between April 2008 and September 2009 to evaluate the effectiveness of two preventive mass vaccination strategies against highly pathogenic avian influenza (HPAI). One regimen used Legok 2003 H5N1 vaccine, while the other used both Legok 2003 H5N1 and HB1 Newcastle disease (ND) vaccine. A total of 16 districts were involved in the study. The sample size was estimated using a formal power calculation technique that assumed a detectable effect of treatment as a 50% reduction in the baseline number of HPAI-compatible outbreaks. Within each district, candidate treatment blocks with village poultry populations ranging from 80 000 to 120 000 were created along subdistrict boundary lines. Subsequently, four of these blocks were randomly selected and assigned one treatment from a list that comprised control, vaccination against HPAI, vaccination against HPAI + ND. Four rounds of vaccination were administered at quarterly intervals beginning in July 2008. A vaccination campaign involved vaccinating 100 000 birds in a treatment block, followed by another 100 000 vaccinations 3 weeks later as a booster dose. Data on disease incidence and vaccination coverage were also collected at quarterly intervals using participatory epidemiological techniques. Compared with the unvaccinated (control) group, the incidence of HPAI-compatible events declined by 32% (P = 0.24) in the HPAI-vaccinated group and by 73% (P = 0.00) in the HPAI- and ND-vaccinated group. The effect of treatment did not vary with time or district. Similarly, an analysis of secondary data from the participatory disease and response (PDSR) database revealed that the incidence of HPAI declined by 12% in the HPAI-vaccinated group and by 24% in the HPAI + ND-vaccinated group. The results suggest that the HPAI + ND vaccination significantly reduced the incidence of HPAI-compatible events in mixed populations of semicommercial and backyard poultry.

Estimating the transmissibility of H5N1 and the effect of vaccination in Indonesia.

The spread of H5N1 avian influenza continues to pose an economic burden and a public health risk worldwide. Despite this, estimates of the transmissibility of infection exist in only a handful of settings and vary considerably. Using final size methods and flock-level infection data from a field trial of mass vaccination, we obtained the first estimates of the transmissibility of infection between and within flocks in Indonesia. We also found that outbreaks in areas designated as vaccination zones were less transmissible than in non-vaccination zones. However, this reduction is only comparable with a limited degree of protective vaccination coverage. Quantifying the overall effect of vaccination in these zones remains challenging. However, this result would appear to imply that, although the interventions applied in vaccination zones were not sufficient to completely prevent transmission in all areas, when outbreaks occur, they are less transmissible than those in areas where vaccination was not applied. This could be either a direct or an indirect effect of vaccination. Given the dynamism of small-scale poultry production in Indonesia, more regular vaccination may be required to ensure that infection is fully controlled in vaccination zones.

Antibody response and risk factors for seropositivity in backyard poultry following mass vaccination against highly pathogenic avian influenza and Newcastle disease in Indonesia

A large-scale mass vaccination campaign was carried out in Java, Indonesia in an attempt to control outbreaks of highly pathogenic avian influenza (HPAI) in backyard flocks and commercial smallholder poultry. Sero-monitoring was conducted in mass vaccination and control areas to assess the proportion of the target population with antibodies against HPAI and Newcastle disease (ND). There were four rounds of vaccination, and samples were collected after each round resulting in a total of 27 293 samples. Sampling was performed irrespective of vaccination status. In the mass vaccination areas, 20-45% of poultry sampled had a positive titre to H5 after each round of vaccination, compared to 2-3% in the control group. In the HPAI + ND vaccination group, 12-25% of the population had positive ND titres, compared to 5-13% in the areas without ND vaccination. The level of seropositivity varied by district, age of the bird, and species (ducks vs. chickens).