Prevalence data on chicken diseases in low-resource settings

The presence of transmissible disease in livestock has a huge impact on welfare and economics in animal and public health. The lack of data enables the spread of diseases due to misinformed decision-making on prevention and control. Low-resource settings face challenges in providing data, turning data availability into a development issue. We collected a large dataset (n=997) on prevalence and seroprevalence estimates on viral (n=224), bacterial (n=83) and parasitic diseases (n=690) in backyard chickens in low-income and middle-income countries (LMICs). These originate from 306 studies identified during the screening phase of a systematic literature review. We attempted to classify studies according to the Food and Agriculture Organization of the United Nations classification system of family poultry production systems. Of all the studies, 98.7% (302/306) focused on a single poultry production system while 1.3% (4/306) targeted two different production systems. Within the group of studies that covered one production system, 85.4% (258/302) were classified as ‘small extensive scavenging or extensive scavenging’, ‘small extensive scavenging and extensive scavenging’. In addition to that, 52% (159/306) of the studies did not report information on the chicken breed type. No data was found on any relevant disease from 56.9% (78/137) of LMICs, identifying a potential data gap. Of the estimates on viral and bacterial diseases, 71.0% (218/307) corresponded to diseases notifiable to the World Organisation for Animal Health, highlighting a tendency to measure disease occurrence on diseases relevant to trade. The latter might not necessarily be priority diseases for the producers, however. Also, 72.3% (222/307) of the estimates originate from random samples and they could be used to estimate prevalence in backyard chickens using imputation methods and thus, bridging the data gap.