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Asian Journal of Agriculture and Development (AJAD) - Call for papers!

Prevalence and risk factors of zoonotic protozoa among smallholder livestock farmers in Aurora Province

(Philippines), Doctor of Philosophy in Public Health (University of the Philippines Manila)

Dissertation Abstract:

This cross-sectional study determined the prevalence and risk factors of zoonotic pathogenic protozoa among animal handlers engaged in small holder livestock farming in Aurora Province. Specifically, the study determined the prevalence of zoonotic protozoa infection among livestock animals by mode of transmission (arthropodborne, water-borne/fecal-oral route, food-bone) and examined for the presence of associations between the different risk factors and zoonotic protozoa infection among animal handlers and livestock.
 
The exposure variables for animal handlers included educational attainment, hand washing practices, high risk farm activities, characteristics of drinking water source, ingestion of raw or uncooked meat, manner of excreta and garbage disposal, sanitary quality and use of toilet, and herd size. Whereas, exposure variables for livestock included 10 percent diarrheal incidence and manner of anti-diarrheal medication in the farm, acaricidal application, entry of new stock, access to natural bodies of water, and presence of animal scavengers (cats and/or rats) in the farm.
 
The study was conducted from June 2007 to October 2009. There were 678 animal handlers enrolled in the study and more than a hundred animals (cattle, buffaloes, goats, pigs, dogs, chickens, and cats) examined. The presence of protozoa was detected by microscopy and PCR from fecal DNA of animal handlers and blood DNA from cattle, buffalo, rats, and animal handlers.
 
Among the zoonotic protozoa affecting the small holder livestock farmers in Aurora Province, four enteric protozoa that could be transmitted by water or fecal oral route were detected. Cryptosporidium parvum had the highest prevalence which was the same for both male and female animal handlers (21%) and the highest among the age groups. Highest prevalence of Cryptosporidium was found in pigs (30%), followed by cattle (27%), similar prevalence in buffaloes and chickens (21%), goats
(18%), and dogs (10%).
 
The second protozoon prevalent among animal handlers and livestock in this
study was Blastocystis hominis. Its prevalence was higher among male (2.4%) than female animal handlers (1.9%). It was detected among animal handlers from ages 26 years old and above. Cattle, buffaloes, goats, pigs, chickens, and dogs were infected with B. hominis with pigs having the highest prevalence (29%). Similarly, all animal handlers whose animals were found infected with B. hominis were also infected with the same enteric protozoa by microscopy.
 
Entamoeba histolytica had a very low prevalence (less than 1%) among animal
handlers by PCR. The prevalence of Giardia among animal handlers was quite low (less than 1%).
 
Both arthropod borne blood protozoa, namely: Babesia microti and Trypanosoma evansi, were not present among animal handlers. However, T. evansi was detected among cattle and buffaloes with prevalence less than 1 percent.
 
Two food borne zoonotic protozoa were examined. In spite of the 30 percent
prevalence of Toxoplasma gondii among cats examined in the study, it was not
detected in the blood DNA samples of all animal handlers by PCR. In spite of the 6.49 percent prevalence of Sarcocystis spp. infection among dogs examined in the study, it was not detected in the blood DNA samples of animal handlers who owned the infected dogs.
 
The study also determined the association between the different possible exposure variables and enteric zoonotic protozoa infection among animal handlers using multiple logistic regressions while controlling for the confounders. Specifically, questionable or poor source of water in an unclean surroundings as evidenced by presence of excreta in the vicinity (OR = 1.79, 95% CI: 1.13, 2.8; p = .014) and good source of water but with excreta in the vicinity (OR = 1.50, 95% CI: 1.0, 3.0; p = .052) were associated with the infection among animal handlers. Lastly, moderate to maximum number of animals in the herd (OR = 1.9, 95% CI: 1.2, 3.0, p = .010) was significantly associated with enteric zoonotic protozoa infection among animal handlers.
 
Among livestock, the presence of diarrhea was significantly associated with enteric zoonotic protozoa infection (OR = 6.43, 95% CI: 1.13, 19.4, p < .001) among cattle. The presence of scavengers was significantly associated with enteric zoonotic protozoa infection while controlling for confounders (OR = 2.7, 95% CI: 1.4, 5.6, p = .005). The presence of diarrhea in the farm (OR = 2.0, 95% CI: 0.8, 5.4, p = .049) was significantly associated with enteric protozoa infection among goats. Access to natural bodies of water (OR = 3.35, 95% CI: 1.3, 8.4, p = .10) and exposure to animal scavengers (OR = 2.9, 95% CI: 1.6, 5.3, p = .001) were significantly associated with chicken infection.