zoonoses and communicable diseases common to ... - PAHO/WHO

MELIOIDOSIS 187with the soil. In the southern part of the same state, which is not an enzootic area,veterinary inspection at a slaughterhouse uncovered cases in suckling pigs fromeight intensive breeding facilities, during three successive years. These cases (159out of 17,397 animals inspected) occurred after abundant rains and flooding.Abscesses were found in the bronchial ganglia of 40% and in the spleen of 34%. Theoutbreak was attributed to inhalation of aerosols from water (Ketterer et al., 1986).The disease is rare in cattle. The etiologic agent has been isolated from splenicabscesses, from the central nervous system, and from aborted fetuses.In horses, the infection may become apparent due to the symptoms of septicemia,colic, diarrhea, and edemas in the legs.The symptomatology is not very characteristic and the disease is difficult to diagnosein animal species in which it occurs sporadically. The lesions, which are similarto those in man, may suggest melioidosis and lead to its diagnosis.Source of Infection and Mode of Transmission (Figure 13): Investigations haveshown that the reservoirs of P. pseudomallei are surface waters and soil, as corroboratedby sampling done in Southeast Asia. The highest isolation rates wereobtained in rice fields and newly planted oil palm plantations (14.5%–33.3% of theisolations were from water samples). Seroepidemiologic studies also show that thehighest reactor rates to the hemagglutination test came from workers or inhabitantsof those areas. Human and animal infection occurs mainly during the rainy season.The etiologic agent can survive for many months in surface water and, with its lownutritional requirements, it can multiply in the hot, humid environment characteristicof endemic regions.Figure 13. Melioidosis (Pseudomonas pseudomallei). Mode of transmission.Contaminated surfacewaters and soilManSheep, goats,horses, swine,cattle, dogs, cats,nonhumanprimates,wild andsemi-domesticrats