Understanding High-Fever Diseases in Pigs in Summer and Autumn in One Article

For the @#@227@#@ industry, summer and autumn can span from May to early November each year. Over this half-year period, pig diseases are commonly seen and frequently occur for many reasons. According to rough statistics, the incidence of pig diseases in summer and autumn accounts for about 70% of the whole year. The notable feature of pig diseases during this period is that clinically they are mainly characterized by high fever, with body temperature mostly rising above 41°C, presenting as continued fever or recurrent high fever. Among the commonly occurring high-fever diseases are: swine fever, swine erysipelas, swine pasteurellosis, piglet paratyphoid, swine septicemic streptococcosis, swine influenza, swine infectious pleuropneumonia, swine toxoplasmosis, swine eperythrozoonosis, etc. In recent years, the epidemic characteristics of high-fever diseases in pigs during summer and autumn are often that one disease occurs first clinically, and then one or two other diseases occur as concurrent or secondary infections, causing inaccurate diagnosis and delayed treatment, which greatly increases the mortality and culling rates and creates cross-regional pandemics. This leaves grassroots veterinary stations confused in clinical diagnosis and treatment, and more importantly causes severe losses to the pig industry in a region, seriously dampening farmers' enthusiasm for raising pigs, thereby hindering agricultural efficiency and farmers' income growth, and even affecting rural stability and unity. In July-August 2006, our city conducted statistics on high-fever diseases in pigs and analyzed the epidemiology, incidence and mortality-culling rates, and transmission factors of affected pigs. The details are as follows:

1 Epidemiological Investigation and Analysis of High-Fever Diseases in Pigs in Summer and Autumn

1.1 Investigation and analysis of disease-causing factors: mainly including natural factors, human factors, market environment factors, and grassroots veterinary system factors. The interweaving of many factors increases the difficulty of epidemic prevention and disease elimination, and greatly increases the incidence and mortality-culling rates.

1.2 Investigation and analysis of disease manifestations: Among the high-fever diseases occurring in pigs during summer and autumn, most can be prevented by effective vaccines, such as swine fever, swine erysipelas, swine pasteurellosis, swine septicemic streptococcosis, piglet paratyphoid, etc. The vaccine quality is up to standard and immunization procedures are clear, but the disease mainly occurs due to missed vaccinations and failure to follow procedures. The remaining 4 diseases mostly occur or become secondary infections due to poor feeding management and lack of sanitation and disinfection. In most areas, the manifestation pattern is that one disease occurs first, followed by one or two secondary or concurrent infections, leading to complexity of the condition and increased difficulty in diagnosis and treatment.

1.3 Investigation and analysis of epidemic areas: High-fever diseases in pigs during summer and autumn have formed cross-regional epidemics. From summer and autumn of 2001, high-fever diseases in pigs swept across the country, with virtually no area spared. The wide epidemic range, severe harm, and great losses to the pig industry were unprecedented since the founding of the People's Republic of China. Among them, the epidemic in urban-rural fringe areas (suburbs) was more severe than in rural areas, in backyard households (thousands of households) more severe than in scale households, and in scale households more severe than in intensive pig farms.

1.4 Investigation and analysis of age, sex, and breed of affected pigs: High-fever diseases in pigs during summer and autumn show little difference in relation to age, sex, or breed. However, in most cases, suckling piglets have lower incidence, while old sows, growing-finishing pigs, and weaned piglets have basically the same susceptibility under the same feeding management and environmental conditions. However, under the same conditions, susceptibility to some specific diseases still differs.

2 Analysis of Incidence and Mortality-Culling Rates of High-Fever Diseases in Pigs in Summer and Autumn

2.1 Based on a 10-year investigation of high-fever diseases in pigs in summer and autumn in this region, under normal circumstances, the average annual total incidence of pig diseases is 13%, and the incidence in summer and autumn accounts for about 70% of the annual total. However, in recent years, the disease situation in summer and autumn has been severe with great changes. For example, in the summer and autumn of 2001, the high-fever disease mainly involving swine influenza reached over 3 million affected pigs in Anhui Province, with an incidence of 16%; Jiangsu Province averaged about 15%; and in the vast pig-producing areas of central and northern Jiangsu, the incidence reached over 18%, with some areas as high as 20%. From July 29 to August 31, 2006, our city had 11,935 cases of high-fever disease in pigs, accounting for 2.7% of the standing herd, with 893 deaths and a mortality rate of 7.8%.

2.2 Since farmers are generally unwilling to spend too much money treating finisher pigs weighing over 50 kg, if the pigs do not improve after several consecutive days of treatment, they sell the sick pigs at a low price to individual butchers for slaughter. This results in a very low cure rate and a very high culling rate. In some areas, the sum of mortality and culling rates even approaches the incidence rate, causing heavy losses to pig farmers.

3 Analysis of Transmission Factors of High-Fever Diseases in Pigs in Summer and Autumn

3.1 Summer and autumn encompass more than two seasonal transitions, such as the transition from spring to summer, from summer to autumn, and even from autumn to winter. During seasonal transitions, the weather often changes dramatically with uneven hot and cold, extreme heat, cold winds, and heavy rain. In addition, farmers' free-range pig-raising methods, simple low and narrow pens, dark and damp conditions, infrequent cleaning, and bites from blood-sucking insects in summer can all lead to decreased pig resistance and thus cause disease.

3.2 Summer and autumn include the two busiest farming seasons in rural areas, namely summer harvest and planting, and autumn harvest and planting. During these busy seasons, farmers focus on farm work and often neglect pig feeding management, causing pigs to have irregular feeding, and even forgetting to vaccinate pigs when vaccination is due, thus leading to disease.

3.3 Missed vaccination issues: such as missed vaccination of old sows, missed vaccination of growing-finishing pigs, and untimely vaccination of weaned piglets, which become the main factors in the occurrence and spread of some epidemics during summer and autumn.

4 Syndrome Differentiation and Treatment of High-Fever Diseases in Pigs in Summer and Autumn

4.1 Focus on improving the professional quality of grassroots veterinary personnel. Enable grassroots veterinary personnel to master diagnostic and prevention methods for common and frequently occurring pig diseases, so that their ability in differential diagnosis and prevention of pig diseases reaches the required level.

4.2 Formulate effective treatment plans. Determine treatment principles; based on the most definitive diagnosis possible, determine the nature of the currently epidemic disease (whether bacterial, viral, or parasitic); based on the vaccines, antisera, specific therapeutic drugs, etc. available locally or on hand, specifically formulate treatment plans for eliminating the epidemic and rescuing sick pigs, isolation plans, emergency vaccination plans, disinfection measures, etc., and immediately organize implementation.

4.3 Promote syndrome differentiation and treatment pilot programs and timely extension. Syndrome differentiation and treatment emphasizes combining symptomatic treatment with root-cause treatment, combining Chinese and Western medicine, combining antiviral drugs with antibacterial drugs, combining oral medication with injections, combining tonifying drugs with purgative drugs, and combining body detoxification with gastrointestinal function regulation. These syndrome differentiation and treatment methods have achieved remarkable results when promoted among grassroots veterinarians.