Prevalence of Xenopsylla cheopis in Rattus rattus in the Salas district, Lambayeque

Objective: The study of the prevalence of Xenopsylla cheopis in rodents of the Rattus rattus species.The objective of the present investigation is to establish the prevalence of Xenopsylla cheopis in rodents of the Rattus rattus species. Methods: To obtain the sample, Tomahawk and Sherman traps were used that contained baits previously prepared with oatmeal and vanilla, the traps were placed in three areas: intra-home area, peridomyciliary area and in the open area. Ectoparasites were obtained using the fine comb technique. With an entomological clamp, fleas were collected in a 2ml vial, containing 70% alcohol. Results: Its prevalence in Rattus rattus rodents were evaluated, with the highest prevalence rate being the one registered in the locality of Banco in August 2016 (4.08) and the lowest index was 1.3 registered in the locality of the Ramada in November 2015. They were captured 169 rodents Rattus rattus, of which 399 fleas could be collected, 299 belonged to the Xenopsylla cheopis species. Conclusion: it was found that the prevalence of Xenopsylla cheopis in Rattus rattus rodents in the locations of Sauce, Banco, Kerguer, Algarrobo, and Ramada in the Salas district, in the period July - November 2015 and August 2016 was high.


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Plague is a zoonotic disease that primarily affects rodents and can be accidentally transmitted to humans or other mammals, mainly through the bite of eas from infected rats, and without treatment reaches high rates

INTRODUCCIÓN
This disease has been linked to the presence of rats, mainly of the species Rattus rattus, Rattus norvegicus, (2) and the ea Xenopsylla cheopis as a vector .
( Fig. 1). Ectoparasites such as Xenospylla cheopis have epidemiological importance, because they can act as transmitters of pathogens including viruses, rickettsiae, bacteria, and protozoa .
The main vector of bubonic plague is the rat and mouse ea, which is Xenopsylla cheopis, which easily leaves its host and can be transferred to other hosts of the same or another species, so it is common to nd them in cats and dogs. . For entomological studies, eas should be sought on animals that live with humans, indicating the (6) infestation rates by species and hosts .
The life cycle of Y. pestis is capable of infecting its main reservoirs through the bite of different species of eas, X. cheopis is the quintessential biological vector of animals of the order Rodentia (more than 230 species involved) and , to a lesser degree, to those of the order (4) Lagomorpha . Fleas of the order Siphonaptera are important in public health, due to their role as vectors of diseases such as bubonic plague, of great historical importance due to epidemics with high mortality; murine typhus and also parasitic diseases such as (5) hymenolepiasis .

METHODS
The population consisted of eas of the order Siphonaptera of the species Xenopsylla cheopis collected from Rattus rattus rodents in the district of Salas in the sectors of: the Banco, the Sauce, the Algarrobo and la Ramada; that were processed in the Laboratory of Environmental Sciences of the Faculty of Biological Sciences and in the Reference Laboratory of Health of the Lambayeque Region.
The objective of this research is to establish the prevalence of Xenopsylla cheopis in rodents of the species Rattus rattus.
The sample consisted of 299 eas of the species Xenopsylla cheopis collected from 135 rodents of the species Rattus rattus in the sectors of: el Sauce, Banco, Kerguer, la Ramada and el Algarrobo in the district of Salas, June 2015 -August 2016.
To obtain the sample, Tomahawk and Sherman traps were used that contained baits previously prepared with oats and vanilla, allowing the capture of the Rattus rattus species (Fig. 2y 3).. 100 traps were placed per day (70 Tomahawk and 30 Sherman traps) interspersing the (1) of mortality .
valleys, highways, trails, with a distance between traps of 10 m.
Subsequently, a colored plastic banner was placed on the traps and the rodent capture form was lled out, which facilitated the location of the traps. Livecaptured animals were placed in a cloth bag containing cotton soaked in chloroform.

Plucking and obtaining ectoparasites of Rattus rattus
De ection began with brushing the animal inside a white box in order to observe the ectoparasites. Ectoparasites were obtained using the ne comb technique. With an entomological forceps, the eas were collected in a 2ml vial, containing 70% alcohol. The samples obtained were labeled with data from each animal indicating the place of capture, productive stage, sex and date, which were transferred to the Reference Health Laboratory for identi cation.

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This is the collection that was made inside a house. 5% of the total number of traps were distributed inside different houses.
The area surrounding the dwelling up to a radius of 25 meters away was considered as peridomicile. 25% of the traps are installed in this area, with the distance between trap and trap being 10 m. Collection in the open area: It was collected anywhere beyond a perimeter of 10 m. around a house. 70% of traps were placed at a distance of 100 m from the inhabited area along fences, irrigat ion aqueducts, streams, small two types of traps with a distance of approximately 5 to 10 meters between each one. The traps were placed in three zones: intra-domiciliary zone, peridomiciliary zone and in an open area. The identi cation of Xenopsylla cheopis eas was

Intradomiciliary collection Peridomiciliary collection
The anesthetized rodents were placed on the autopsy table previously conditioned, proceeding to carry out the measurements, observation of the color of the body fur (dorsal and ventral), appearance of the tail fur, total length, head length, body length, ear, weight, sex, number of embryos and note some morphological alterations, which were recorded in a rodent evaluation form. The ectoparasites were collected and stored in a 2 ml vial and placed in a Petri dish with 70% alcohol and then visualized in a stereoscope, with the help of plastic pipettes and ne needles, the eas were transferred to slides, with 10% sodium hydroxide clarifying solution, achieving a better visualization and identi cation in a stereoscope. (7) carried out based on the key of Acosta and Morrone .

RESULTS
Three epidemiological surveillances were carried out in two time periods July -November, 2015 and August 2016 in the localities of: the Sauce, the Banco, the Algarrobo, Kerguer and la Ramada of the district of Salas of the department of Lambayeque, where the dwellings of the inhabitants of the mentioned localities to place the respective traps.
In july 2015, only the towns of Sauce, Banco and Algarrobo in the district of Salas were visited, where rodents of different species were captured, the rodents from the intradomiciliarys and peridomiciliarys areas all belonged to the Rattus rattus species; while in the wild area rodents of the species Akodon mollis and Oryzomis xantheolus were captured.   In the period that includes the months of July, 2015 -August 2016, high trapping rates were recorded (7% -24%) higher than the risk rate according to the Pest  Table 2 shows that during the month of July 2015 in the town of Algarrobo, of the 13 Rattus rattus rodents, 40 eas were collected, obtaining a general index of 3.08; while in the town of El Banco out of 7 rattus rattus rodents captured, the general index of eas is 2.14, which is lower compared to the other town.
After having obtained the rattus rattus rodent trapping index in the different localities of the Salas district, the general ea index and the speci c ea index were evaluated, which were obtained considering only the number of rodents trapped from the species Rattus rattus. The eas were collected in vials containing alcohol, which were labeled and taken to the Reference Health Laboratory to be quanti ed and identi ed.
trapping rate of 30% and 20% was recorded in the Sauce and Banco locations, respectively (Table 1).

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24,025 eas, only 0.2% were Xenopsylla cheopis. The observed characteristics were similar since this species presents an ocular bristle in front of the eye and a divided mesopleura; characteristics that also coincide (7) with those described by Acosta and Morone . The high rate of Xenopsylla cheopis in the district of Salas was higher, which could be related to the increase in reservoirs and contact with domestic animals in this (12) area .
The higher capture rate would be due to the fact that these Tomahawk traps are larger than Sherman traps, which would make it easier to capture Rattus rattus.
Likewise, this species has a high power of adaptation, which is why it is found both in the intradomiciliary, peridomiciliary and even in the wild zone. It was also To determine the prevalence of Xenopsylla cheopis, the rodent trapping rates, the general ea rate and the speci c rate were established. The trapping index of Rattus rattus when using the Tomahawk traps in the Salas district localities was higher in the intradomiciliary zone with respect to the peridomiciliary and wild zone; on the other hand, when using the Sherman traps, the trapping rate was lower. These results were similar to which correspond to the morphological characteristics (9) described in the Pacheco and Arana key .

DISCUSSION
These results were similar to those obtained by Hamsa 399 eas were collected from 135 Rattus rattus rodents, of which 75% belonged to Xenopsylla cheopis; (11) however, in the investigation by Pozo in Piura, of These results were also similar to those obtained by (13) Carpio , who in Lambayeque recorded that the Speci c Index for Xenopsylla cheopis was 6.1 and for Polygenis sp. of 3, with which we could say that the Ctenocephalides felis were identi ed, obtaining a percentage of 75%, 11%, 12% and 2% respectively.
The prevalence of the ea Xenopsylla cheopis in Rattus rattus rodents during the evaluated period varied between 1.3 to 4.08, obtaining an average of 2.6, being higher than the Peruvian risk index. These data suggest that epidemiological vigilance should be maintained and preventive measures adopted in these areas and nearby places in order to avoid an outbreak of plague.

Authorship contributions:
The authors carried out the design, data collection, preparation, critical review and approval of the nal version of the article.

Con icts of interest:
The authors declare that they have no con icts of interest in the publication of this article.