Effect of vaccine storage temperatures and dose rate on antibody responses to foot and mouth disease vaccination in Cambodia

A field study investigated the effects of foot and mouth disease vaccine storage temperature for 7 days (frozen, refrigerated or held at ambient temperature) and dose (half or full dose) on the serological response to vaccination. It utilised a complete factorial design replicated on 18 smallholder cattle farms in three villages in Pursat province, Cambodia. Antibody responses from the 108 cattle involved were assessed by serological examination of blood samples collected at primary vaccination (day 0), at booster vaccination (day 30) and finally at 60 days post primary vaccination. Vaccination responses to the inactivated vaccine were assessed by testing for antibodies directed against FMD structural proteins in a liquid-phase blocking ELISA (LPBE test) and differentiated from responses to natural infection by examining antibody titres against non-structural viral proteins (NSPE test). LPBE results indicated that the mean log10 LPBE antibody titres of all experimental cattle increased from below protective levels at day 0 to protective levels at 30 days post primary vaccination, and increased further at 60 days post primary vaccination. Storage at ambient temperature for 1 week had no effect on antibody response to vaccination. However, freezing the vaccine for a week or use of a half dose resulted in significant reduction in titres at day 60 (P = 0.04 and P = 0.02, respectively). The results of this study reinforce the need to store FMD vaccines within the range recommended by the manufacturers and to adhere to the specified dosage instructions

An investigation into the efficacy of foot-and-mouth disease control programs in cattle in Cambodia

Foot and mouth disease (FMD) is a highly contagious viral disease which impacts national and regional economies and the livelihoods of smallholder farmers. Due to the limited human and financial resources and difficulties in enforcing animal, people and product movement regulations, it is almost impossible to control FMD in Cambodia. The best option for control would be to implement an efficient and equitable vaccination program with the support of all stakeholders, neighbouring countries and multilateral donors. The aim of this thesis is to investigate the efficacy of FMD cattle vaccination programs in Cambodia. This required information and data collection from smallholder farmers (livestock producers), village animal health workers (local animal health service providers) and vaccine retailers (vaccine suppliers) as well as other inputs from relevant stakeholders. This initial analysis identified the importance of cold storage temperature variation and the potential effects this may have on vaccine efficacy and smallholder's desire to participate in FMD control programs. It also identified the important role that smallholders play in the potential success of these programs and their perceptions of household benefit. Two major research activities were undertaken. Firstly, two FMD vaccination experiments to identify the effect of vaccine storage temperatures and dose rate on antibody responses to FMD vaccination and secondly, an on-farm economic analysis (benefits and costs) of an FMD vaccination program. FMD vaccination programs were implemented using unreliable and limited government support. Private FMD vaccination services did not exist in the study areas. Vaccine handling and cold storage management were poor in both veterinary drugstores and Provincial Offices of Animal Health and Production. The experimental study on the effect of vaccine storage temperatures and dose rate on antibody responses to FMD vaccination found that freezing vaccines for a week did have a deleterious effect on the antibody response while ambient temperature well above recommended temperature range did not have an effect on antibody response. Halving the dose significantly reduced the antibody response to vaccination. A significant deviation from recommended temperature range for up to a week had significant effects on antibody titre. The results highlight the need for improvements to avoid ongoing exposure of vaccines to freezing and high ambient temperatures. Current vaccination coverage could not be expected to ensure herd immunity. The economic analysis suggested that FMD vaccination, including farmer training and deworming programs, can be justified if properly planned and implemented. The economic benefits of participating in an FMD vaccination program were influenced by; the success of vaccination, the success of treatment and nursing and the proportion of sick animals treated. Economic losses to affected farmers were also influenced by the severity of FMD outbreaks. The results will be useful inclusions in the farmer training and vaccination campaigns. Based on the results of this study, it is concluded that current FMD vaccination efforts are ineffective in the study areas. The complex issues along the whole livestock production chain and the endemic nature of the disease pose real challenges. This study calls for improvements in future vaccination practices and FMD awareness campaigns. In order to improve the efficacy of the FMD control programs, the Department of Animal Health and Production requires significant government financial support and vaccination programs would be more effective if only targeted in FMD high risk areas. It is recommended that private FMD vaccination program is developed and implemented to reduce the number of susceptible animals in Cambodia. To achieve this the national and provincial offices of animal health and production need to ensure that farmers and village animal health workers understand and can implement their roles in the government subsidised and private FMD vaccination programs. It is suggested that a training program to teach proper storage and handling of livestock vaccines is required for both government and commercial vaccine managers. The control of FMD within the country will have significant benefits for individual smallholder farmers, and also the Cambodian economy

Knowledge, attitudes and practices of smallholder farmers on foot and mouth disease control in two Cambodian provinces

Food-and-mouth disease (FMD) is endemic in Cambodia. The control programme for FMD has relied on vaccination, with poor vaccination uptake by smallholder farmers becoming an increasing concern. A study to improve the understanding of farmer knowledge, attitudes and practices of FMD control and vaccination was conducted in two Cambodian provinces (Kampong Cham and Pursat). The aim was to identify opportunities to improve the livestock disease control programmes provided by both the government and private sectors. The survey comprised 300 smallholder farmers using a one-on-one interview technique and was completed between January to February 2014. Results identified that over two-thirds of the respondent farmers had not vaccinated their cattle over 2 years (2011–2013). Of those who did, most cattle were vaccinated either once a year or once every 3 years. A booster had never been administered. It was concluded that the FMD vaccine had only been administered through an unreliable and limited government vaccination programme, and private FMD vaccination services were not accessed in the study areas. FMD outbreaks occurred every year during the study period, with a morbidity rate of over 30%. Isolation of first infected cattle from the household herd was not practiced, with treatment identified as the first preference intervention. Farmers often assisted other farmers to restrain and treat infected cattle both before (57%) and after (43%) their own cattle were infected. This indicated that most farmers did not practice basic biosecurity measures and chose to report FMD outbreaks to the village animal health workers (VAHW), friends, neighbours and relatives in preference to government officials. It was concluded that poor knowledge of disease transmission and biosecurity, with low FMD vaccination coverage and a focus on treatment, contribute to regular FMD outbreaks in these communities. Improvement of FMD control requires the cooperation of villagers, VAHWs and village leaders in disease reporting, with either improved funding of government vaccination services or establishing a private FMD vaccination service. Training programmes for farmers on disease transmission, and the importance of biosecurity and vaccination, including information on the cost-benefits of treatment versus full fee bi-annual FMD vaccination, are required