Two communities are visited in the period May 2018 to December 2019: Usibamba and Chaquicocha, belonging to the San José de Quero district, Concepción province, located in central Peru at 4000 meters above sea level with temperatures ranging between -4 ° C and 16 ° C. These two communities have 2,193 inhabitants and are endemic to CE (Graph 1).
There is not enough information on the number of dogs living in the study area to evaluate the size of the sample, this was calculated on an unknown population with an expected prevalence of 28% of dogs infested with E. granulosus in endemic áreas (Acosta et al., 2014), 95% as confidence interval, 80% power and adding 10% for probable losses. The analyzed sample was 252 stool samples, using the proportions method with the statistical program Stata v. 13.1 (Stata Corporation, Texas, USA).
Design and Procedures
A quasi-experimental study of a single cohort of dogs from a CE endemic area was conducted. Before the intervention, the dwellings were randomly chosen by strata according to the proportion of inhabitants of each community and each street, with the support of the demographic survey of the municipality of San José de Quero, satellite images and a geographical map.
All the dogs present in each selected house were sampled, if the occupants of a house were absent, refused to participate in the study or did not have a dog, we selected a neighboring house and previously asked about the presence or absence of dogs. The process continued until the sample size was completed. With prior informed consent to the owners, the information was collected using a structured and validated form. A Bulletin was delivered with information on the importance of deworming and the prevention measures for CE. Fresh stool samples were obtained, maintaining biosafety measures. The fecal samples were deposited in a bottle with 10% formalin and kept refrigerated at 4 ° C. Then, they were transported to the microbiology department of the Institute of Tropical Medicine - National University of San Marcos for microscopic identification. Fresh feces samples were also collected from the fields and the main square from the stray dogs in order to microbiologically compare the results.
The microscopic examination of fecal samples preserved in 10% formalin, the direct method was carried out, which consists of dissolving the sample well, keeping it at rest for 5 minutes and with the help of a Pasteur pipette, taked a drop from the bottom and place it in a slide, protected with a coverslip and observed under a microscope at 10 and 40X magnification. The objective of this procedure was to identify the presence of other parasites.
The diagnosis of canine echinococcosis was made by analysis of coproantigens, using the commercial immunoenzymatic technique (ELISA) for E. granulosus (Cestodas Zoonoses Research Group, University of Salford) (Verastegui et al., 1992). The same technique was used for both stool samples.
Due to the unevenness of the working area surface, an electronic scale was used to calculate the dog's weight, the owner loaded the dog on the scale, and then the difference from the owner's weight was subtracted to obtain the dog's weight. For stray dogs, the weight of the dogs was roughly calculated according to external characteristics.
Dogs received 2 cycles of treatment, with a 12-month interval between each cycle, in each cycle received three doses of praziquantel, one dose per month. The first treatment cycle began in May 2018 and the last cycle began in June 2019. Dog stool samples were collected at the beginning of the first cycle and at the end of the second treatment cycle.
Praziquantel 5 mg / kg was administered orally to dogs every 30 days for three consecutive months, every 12 months for two consecutive years, dogs received 6 doses in 2 years. The stray dogs found in the parks were also dewormed, the antiparasitic praziquantel was combined with bread or chicken, the stray dogs received a dose and frequency similar to other dogs, a photograph was selected in each deworming process to identify the dog. The administration of the medication went directly to the dog and under supervision, the medication was not delivered to the owner or to the health center.
During each home visit, the messages on prevention of CE were reinforced and the delivery of informative material, in addition, an antiparasitic card was given to the owner and it was marked each time the dog received antiparasitic treatment, in the same way that the information on the effects was obtained adverse presented by the dog. Not finding the owner, we visited him the next day to complete the canine deworming process.
One month after the last deworming cycle, in September 2019, stool samples were collected again in the same way as before the intervention and transferred to the microbiology laboratory to identify the parasite, maintaining the same detection technique for antigens.
Microsoft Excel for Windows was used for the double data entry process. STATA version 13.0 for Windows (STATA Corp, College Station, TX, USA) was used for the analysis. Initially, a description of the demographic characteristics was tabulated according to the general characteristics of the dogs before the intervention. Categorical variables were compared using the Chi square test or Fisher's exact test as appropriate. While the numerical variables were compared by Student's t test. In addition, the mean of quantitative variables such as the age of the dog and the number of dogs per house was calculated for each group according to the positive or negative result of E. granulosus.