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Effect of DeWorming Drugs for Intestinal Parasites Control on Laboratory Rats  (Rattus norvegicus) Breeding in DMR 

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*Corresponding author:  
Dr. Maung Maung Mya  
Deworming drug 
Pinworms remain most prevalent in laboratory mice and rats. Rats are  usually infected with Syphacia muris and mice with Syphacia obvelata and  Aspiculuris tetraptera. Therefore, the study was conducted to eliminate  worm infection using deworming drugs on laboratory rats in DMR during  the study period from March 2021 to February 2022. In of rats the present  study, thirty males and thirty females of Wistar rats (Rattus norvegicus)  from DMR were randomly selected and 10 each were housed in cages  separately according to the treatment of three deworming drugs as  fenbendazole, albendazole and parazivet groups of rats. Before the  treatment of deworming drugs, all groups of rats were detected worm  parasite’s eggs by the method of taping (Graham). Out of 60 rats,  55(91.67%) rats were positive for both Pinworm (Syphacia muris) and  Ascariasis (Ascaris suum) eggs. Of these, the highest density of mixed  infection was found 40 (72.73%) (Pinworm + Ascariasis) followed by  Pinworms only 8(14.55%) of rats and lowest positivity was observed Ascaris  suum eggs only 7(12.73%) rats respectively. Among them 28 (93.33%)  samples of males and 27 (90%) samples of females were found parasite  positive. After treatment of deworming drugs, 100% reduction was  observed in all groups of rats. All the deworming drugs were found very  effective to control the Pin worm and Ascariasis infection. To reduce  reinfection, monthly treatment is needed to control or eliminate the worm  infection in laboratory animals.  


Pinworms are most prevalent in laboratory mice and rats  (Clifford and Cosentino 006a,b; Livingston and Riley  2003). Rats are usually infected with Syphacia muris and  mice are infected with Syphacia obvelata and Aspiculuris  tetraptera (Baker, 2007). Rats can be incidental hosts of  Syphacia obvelata and mice can be incidental hosts of  Syphacia muris (Baker, 2007, Phillipson, 1974). And also  rats are infected with Aspiculuris tetraptera (Mathies, 1959).

In the late 1980s and early 1990s, some viruses prevalent in laboratory mice such as Sendai virus, mouse hepatitis virus (MHV), epizootic diarrhea of infant mice  (EDIM), and the only parvovirus and helminths are  prevalent in laboratory mice and rats. In rats, the picture  was similar, with prevalent of viruses including the Sendai  virus, coronavirus (also called sialodacryoadenitis virus,  SDAV), and the rat parvoviruses. In addition to the  viruses, pinworms were prevalent in both mice and rats  (Casebolt et al. 1988; Jacoby and Lindsey, 1998; Lussier  and Descoteaux, 1986). Pinworms are nematode parasites (Family Oxyuridae) that have simple, direct life  cycles and are frequent contaminants of both specific  pathogen free (SPF) and conventional colonies of  laboratory rats and mice. 

Pinworms are transmitted through the ingestion of  embryonated eggs. Two species of pinworms Syphacia  obvelata and Aspiculuris tetraptera commonly infect  laboratory rats and mice. The prevalence of pinworms in  an infected rodent population depends on many factors,  including parasite environmental load, gender, age,  strain, and immune status. Males tend to have higher  burdens than females, while young animals tend to have  higher worm burdens than older animals. 

Mice and rats are the most common laboratory animals  used in research and testing of many kinds of traditional  and pharmaceutical research. The parasite infections can  affect investigations by inducing physiological and  immunological alterations in the hosts, increasing or  diminishing host susceptibility to experimental stress,  inducing tissue damage, stimulating abnormal tissue  growth, competing with the host for nutrients,  decreasing the volume of the host’s blood and body fluids  and by mechanical interference (Baker, 2007). Still little is  known about the effects of environmental changes on  the biological variation in experimental results (Stahl  1963). In the mouse and rat caecum and colon,  Qspicularis tetraptera may be found together with  Syphacia muris or Syphacia abvelata (Taffs, 1979). 

Syphacia muris is the most prevalent pinworm of rats.  The life cycle of Syphacia muris is direct and completed in  7 to 8 days, (Lewis and Silvq, 1986) making this particular  pinworm ideal for epidemiologic study. Adult worms of  Syphacia muris inhabit the cecum and colon, and female  worms migrate to the anus and deposit all their eggs on  the perianal region of the host before dying.

Within a few  hours, the eggs developed into embryonic and they are  considered infective (Stahl, 1963). Infection is believed to  occur via 3 modes: (1) direct ingestion of the eggs; (2)  ingestion of food or water contaminated with the eggs;  and (3) retro infection (Chan 1952). Ingestion of eggs is  considered to be the primary mode of infection, and the  eggs are reported to remain viable within the  environment for as long as 4 weeks (Cliford and Watson,  2004, Dix et al. 2004).

Antemortem diagnosis traditionally  is made by identification of these eggs on a perianal  cellophane tape, given the ease of collection and  interpretation, although direct examination of the cecum  postmortem is considered the most dependable method  for Syphacia muris diagnosis (Anya, 1966). 

Ascariasis prevalence was found in humans and animals  Kindem. Ascaris suum is mostly infected to rats, mice,  swine and pigs. Ascaris suum infection is established  orally by third stage larvae after their development from  embryonated eggs. The third stage larvae invade the  small intestine of host migrate into the lever and lung,  and finally reach to the cecum and/or proximal colon,  where they develop into adult worms (Tsuji et al. 2003).  

Ethiopian Study revealed that the prevalence of  helminthiasis was higher in mice (28.57% than in rats  (7.41%) (Derothe et al. 1997). Internal and external  parasites remain a significant concern in laboratory  rodent facilities, and many research facilities harbor  some parasitized animals (Institute for Laboratory Animal  Research, 2011). This study reported that the data on the  presence of helminth parasites, mainly with regard to  pinworm species in laboratory rat colonies.

At the same  time, to fine out the effectiveness of deworming drugs on  helminth parasites in laboratory rats colonies of DMR.  Therefore, the objective of the study was to fine out the  effectiveness of deworming drugs for intestinal parasites  control on laboratory rats (Rattus norvegicus) breeding in  DMR. 


Study Area 

The study was conducted on laboratory rats in the  Laboratory Animal Service, Department of Medical  Research, Ministry of Health, Yangon, Myanmar. 

Study period 

The study period was one year, from April 2021 to March  2022. 

Study Design 

Laboratory based descriptive study design was used. 


Thirty males and thirty females of Wistar rats (Rattus  norvegicus) from DMR were randomly selected.  Laboratory rats were housed in cages (250 mm x 170 mm  x 100 mm) of their breeding rooms separately. The  temperature and humidity of the experimental room was  maintained at 22±2°C and humidity 80-90%. An exhaust  fan and air-conditioner were provided for good air  ventilation in room.

Selected rats were given to free  access the diet and tap–water. Before the experiment, 10  Male and 10 female each of rats were separated into 6  different cages (3cages for male and 3 cages for female).  Cages were labeled according to three deworming drugs(fenbendazole, albendazole and parazivet) respectively  and then all the rats were detected pin worms eggs using  taping method (Graham, 1941), after that each group of  rats was treated with deworming drugs according to  treatment regimens for rats and mice were described in  the reference literature. For rats, treatment generally  involves a week-off feeding containing fenbendazole.  

Pinworm eggs are resistant to desiccation and many common disinfectants, but are susceptible to high  temperatures. In this experimental study, different  deworming drugs (fenbendazole, albendazole and  parazivet) were applied to selected groups of rats.  According to the instruction of therapy, it was done by  oral administration of 10mg/kg/day for 10 consecutive  days. After 7 days of treatment, all groups of rats are  checked, and detected the Pinworm and Ascariasis  parasite’s eggs again by the method of taping (Graham, 1941). 

Analysis of Data 

The mean and standard deviation of each parameter  were calculated by standard statistical methods. The  positive rate was calculated in percent.  


Table 1. Shows that before the treatment of deworming  drug in the rat population, the positivity rate of eggs was  found, in 55(91.67%) out of 60 rats for both Pinworm  (Syphacia muris) and Ascaris suum eggs. Of these, the  highest density of mixed infection (Pinworm + Ascariasis)  was found in 40 rats = (21male +19 females) (72.73 %) in  the rat’s population, followed by (14.55 %) of only  pinworms (Syphacia muris) positivity 8 (3 males + 5 females), and lowest positivity was observed 7 (4 male + 3 Female) (12.73 %) of only Ascaris suum eggs. 

Table 1. Positivity rate of Pinworm and Ascariasis eggs, before and after treatment of deworming drugs in  laboratory-reared Wistar rats (Rattus norvegicus) from DMR 

Rattus  norvegicusNo. of  SampleTreat ment  of  drugsBefore treatment Total  positi veAfter treatment
Pw eggs +ve  (Syphacia  muris)Ascaris suums  eggs +ve (A. )Mixed  (Pw+Asca riasis)Pw  Eggs +veAscar  eggs  +veMixed %  Reducti on
Rats (Males)10 FBZ 10 100
10 ABZ 100
10 PZV 10 100
Rats  (Female)10 FBZ 100
10 ABZ 10 100
10 PZV 100
Total 60 8 (14.55%) 7 (12.73%) 40  (72.73%)55 100
Total + ve 60 55 (91.67%)

FBZ= Fenbendazole, ABZ=Albendazole, PZV = Parazivet, Pw=Pin worm, Ascar=Ascariasis, +ve=positivity A total of 30 males and 30 females were tested for intestinal worms parasites before deworming drugs  administration, 28 (93.33%) samples of males and 27  (90%) samples of females were found worm parasite positive. Of these 10 each of the rats was positive for  pinworm and ascariasis eggs of PZV Parazivet and FBZ  Fenbendazole group.

And 8 rats were found positive for  both parasite aggs in ABZ Albendazole group. In female  groups 10 rats were positive in ABZ Albendazole and 9  and 8 female rats were positive for pinworm and  ascariasis in FBS and PZV groups. After treatment of  different deworming drugs as Fenbendazole,  Albendazole, Parazivet, on rats, all the rats were found  parasite eggs negative and a 100% reduction was  observed in all groups of rats. 


Mice and rats are very useful animals in different kinds of  research in the laboratory. Some are useful for cancer  research, some are useful for snake bite research, some  are useful for bone healing research and some are useful  for toxicity research. Therefore, healthy laboratory  animals are needed to access accurate and good results.  In the present study before the treatment deworming  drug laboratory rats were found pinworm (Syphacia  muris) and Ascaris suum eggs positive by the examination  of the tapping method under the compound microscope  with 40X lance.

A total of 60 laboratory rats (30 male + 30  Female) were examined 28 male and 27 female rats were positive for pinworm and ascariasis eggs. Of these  pinworm and ascariasis mixed positivity was found higher  than individual parasite eggs positivity in both male and  female rats. In the male group 21 rats were infested with  mixed (pin worm + Ascariasis) infection, only 3 were  pinworm eggs and 4 were Ascariasis eggs positive. Similar trim of infection results as male has been found in female  groups.

In female groups 19 mixed positivity of pinworm  and ascariasis eggs and 5 was pinworm and 3 were  ascariasis eggs positive individually and finding observed  that male rats have a higher burden of infection than  female rats. It may be due to pinworm infestations  continuing because of prolonged infections, inefficient  diagnosis, and the survivability of eggs of some species in  the environment.

Other researchers revealed that the  prevalence of pinworms in an infected rodent population  depends on many factors, including environmental load,  gender, age, strain, and immune status. Males tend to  have higher parasite burdens than females, while young  animals tend to have higher worm burdens than older  animals. Laboratory mice tend to be more resistant to  experimentally induced infection than wild mice. Athymic  mice, as might be expected, have an increased  susceptibility to infection (Meade. and Watson, 2014).

In the present study, rats were infected with Ascaris suum in high density, which is morphologically different from  Ascaris lumbricoides (Maung, 1973). Recent studies have  revealed that Ascaris suum of swine origin can develop in  humans, indicating its zoonotic importance (Anderson et  al. 1993; Peng et al. 1988). Although numerous studies  have been carried out thus far to characterize the two  species of parasites on a morphological basis, species  discrimination between Ascaris lumbricoides and Ascaris  suum has been controversial (38 Abebe et al. 2002;  Kurimoto, 1974; Maung, 1973; Nielsen et al. 1997). 

After being treated with different deworming drugs  (fenbendazole, albendazole and parazivet) in rat groups,  all the parasite eggs were disappeared or negative in  three tested groups of rats by the diagnosis of the taping  method. All the rats were free from pinworm and  Ascariasis eggs after treatment of 7 days. Meade and  Watson (2014) revealed that egg hatching after  treatment with chlorine dioxide was significantly reduced  as compared with that of unexposed control eggs (P <  0.01). Eggs exposed to 400 mg/L chlorine dioxide gas  hatched at a rate of 0.3%. Biologic indicators supported  efficacy of the gaseous treatment.

Furthermore, these  eggs showed morphologic differences in the appearance  of the capsule, as compared with control eggs. Liquid  forms were significantly (P < 0.01) less effective at  preventing hatching than the gaseous form of chlorine  dioxide. On the basis of his data, he recommended that perianal tape testing should occur as close as possible to  the peak egg-shedding time of 1400, to maximize the  sensitivity of this particular diagnostic test (Meade and  Warson, 2014).  

In the present study, all the infected rats were found free  from pinworm and ascariasis eggs after treatment with deworming drugs, although other researchers informed  that Eggs may contaminate ventilation ducts (Hoag, 1961)  or shared equipment or procedure areas (Huerkamp, 1993) and can recontaminate a colony after the  completion of treatment. Knowledge of egg longevity in  the environment is important to determine the need for  environmental decontamination, but specific data are  unavailable.

Aspiculuris tetraptera eggs are thought to be  long-lived in the environment, remaining dormant for  several months at 4°C Stahl 1966). Anya (1966a)  reported, however, that culturing newly shed eggs at  37°C accelerated embryonation, decreased the number  of viable eggs, and reduced their longevity. In a study to  determine methods to inactivate viable Syphacia muris eggs, 100% inactivation occurred only with temperatures  of 100°C for 30 minutes and ethylene oxide, although  high killing rates with formaldehyde and chlorine dioxide  suggested that these chemicals could be successful with adjustments to the protocol (Dix et al. 2004). Huerkamp  and colleagues (2000) reported the eradication of S. 

muris without environmental decontamination,  suggesting that the eggs in the environment may not  have outlived the treatment period (fenbendazole in feed  every other week for five treatments). S. obvelata eggs  appear to be unstable, they are reported to survive only  42 hours under ideal conditions, and may be inactivated  by drying or immersion in liquids (Chan 1952; Grice and  Prociv, 1993). As noted above, Syphacia muris eggs are  resistant to the most common disinfectants (Dix et al.  2004), and it is assumed that Aspiculuris tetraptera eggs  have similar properties.

Physical methods (e.g., scrubbing  with detergent, steam cleaning, or painting) are thus  most likely to be effective for environmental  decontamination. Biosafety cabinets used to protect  mice from aerosolized pathogens may actually be a route  to widespread egg dissemination given that eggs shed in  the cabinet are resistant to the routine disinfectants used  to prevent transmission of other pathogens between  cages. Tsuji and associates suggest the possibility of  developing a mucosal vaccine for human and pig  Ascariasis prevention. One of the current golds in the field  of human and veterinary vaccines is the development of  a noninvasive and practical route for administration via  the mucosal surfaces (Tsuji et al. 2003).

The same author  previously developed a nasal immunization technique with rAs14 that involvers protective immune responses  against Ascaris suum infection (Tsiji et al. 2001).  

Clifford and Watson (2008) revealed that, Long recognized agents that remain in research facilities in the  21st century include parvoviruses of rats and mice,  mouse rotavirus, Theiler’s murine encephalomyelitis  virus (TMEV), mouse hepatitis virus (MHV), and  pinworms.

The reasons for their persistence vary with the  agent. The resilience of parvoviruses, for example, is due  to their resistance to inactivation, their prolonged  shedding, and difficulties with detection, especially in  C57BL/6 mice. Rotavirus also has marked environmental  resistance, but periodic reintroduction into facilities,  possibly on bags of feed, bedding, or other supplies or  equipment, also seems likely. TMEV is characterized by  resistance to inactivation, periodic reintroduction, and  relatively long shedding periods.

Although MHV remains  active in the environment for at most a few days,  currently prevalent strains are shed in massive quantities  and likely transmitted by fomites. (Clifford and Watson  2008). In the present study after treatment with Fenbendazole, Albendazole, Parazivet, and deworming drugs, all the rats were found parasite eggs negative, and  a 100 % reduction was observed in all groups of rats.

All the deworming drugs were found very effective to  control both pinworm and ascariasis infections. Monthly treatment is needed to control or eliminate pinworm and  Ascariasis reinfection in laboratory animals.  


Pinworms and ascariasis remain prevalent in laboratory  mice and rats, swine, and pigs. Rats are usually infected  with pinworm Syphacia muris and mice with Syphacia  obvelata and Aspiculuris tetraptera as well as Ascaris  suum in both rats and mice in laboratory. Therefore, it  was needed to eliminate worm infection in laboratory  rats. For this purpose, thirty males and thirty females of  Wistar rats (Rattus norvegicus) from DMR were randomly  selected and 10 each were housed in cages separately for  three deworming drugs fenbendazole, albendazole, and  parazivet) were applied to selected groups of rats.

Results  found that 55 (91.67%) out of 60 were positive for Pin  worm and Ascariasis eggs. Of these the highest density of  mixed infection (Pinworm + Ascariasis) was found in 40  (72.73 %) followed by 8 (14.55 %) was pin worms positive  and the lowest positivity was observed in 7 (12.73 %) of  Ascariasis eggs. A total of 30 males and 30 females were  tested, 28 (93.33 %) samples of males and 27 (90 %)  samples of females were found parasite positive.

After treatment with deworming drugs, all the rats were free  from parasite eggs and a 100 % reduction was observed in all groups of rats and very effective to control both  pinworm and ascariasis infection. And need to prevent  from pinworms and Ascariasis reinfection in laboratory  animals by monthly treatment of deworming drugs. 


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