Skip to main content
NCBI home page
Journal of Parasitic Diseases: Official Organ of the Indian Society for Parasitology logoLink to Journal of Parasitic Diseases: Official Organ of the Indian Society for Parasitology
. 2013 Jan 29;38(3):311–316. doi: 10.1007/s12639-013-0241-5

Evaluation of two Iranian domestic ovine breeds for their pathological findings to gastrointestinal infection of Haemonchus contortus

Javad Javanbakht 1,✉, Ehsan Hosseini 2, Shadi Mousavi 3, Mehdi Aghamohammad Hassan 4, Simin Salehzadeh Kazeroni 5, Fariba Khaki 1, Rooholla Fattahi 6, Meysam Jani 3, Samad Alimohammadi 7
PMCID: PMC4087315  PMID: 25035592

Abstract

The generally warm, moist environmental conditions in the Northwestern Iran are ideal for survival and growth of the egg and larval stages of Haemonchus contortus and other gastrointestinal nematodes (GIN) of sheep and goats.A total of 2,421 animals were slaughtered and examined from July 2010 to July 2011 in Urmia abattoir. In case of sheep, 225 out of 2,421 were positive and prevalence of H. contortus infestation was 9.3 %. Sex wise prevalence of H. contortus in sheep was 33.08 % (76/229) in male and 66.22 % (149/225) in female. The females indicated significantly (P < 0.05) higher prevalence (66.22 %) as compared to males (33.08 %). The highest prevalence was recorded in the spring (April) and the lowest was in summer (July), respectively. On microscopic examination, infiltration of mononuclear cells and eosinophils in gastric glands, periglandular hyperemia and hemorrhage, mucous gland hyperplasia, connective tissue proliferation and necrosis was observed. Also, in mixed abomasal infection with Haemonchus and Ostertagia species, mucosal hyperplasia and increased mucous glands and sometimes cystic glands were seen. Statistical analysis using SPSS software, and Chi-square test, demonstrated a non-significant difference between ages and abomasal PH values of infected and healthy sheep (P < 0.05). But the difference between sexes, seasons and abomasal lesions was significant (P > 0.05).

Keywords: Abomasal, Haemonchus, Sheep, Urmia, Statistical

Introduction

Haemonchus contortus is a blood-feeding gastrointestinal nematode (GIN) that dwells in the abomasum of small ruminants (goats and sheep) particularly in humid temperate and subtropical climates (Amarante et al. 2005). This parasite can cause severe production losses in these animals. The development of multi-drug resistance by H. contortus parasites has driven research into alternative control measures, including selection of sheep genetically resistant to GIN infection. Genetically resistant sheep (either through breeding selection or use of local indigenous breeds) are increasingly considered as viable alternatives to increase animal production (Amarante et al. 2009) and to learn novel mechanisms of resistance not described in commercial breeds (Piedrafita et al. 2010). Importantly, GIN parasites may not adapt to these resistance mechanisms in such selected sheep (Kemper et al. 2009). However, to date the mechanisms underlying the genetic resistance of sheep to GIN infections are largely unknown. H. contortus is of primary concern since it is a highly pathogenic blood-feeder helminth that causes anaemia and reduced productivity and can lead to death in infected animals (Burke et al. 2007). In most production systems lambs are moved from barn to pasture directly after weaning, facing helminth infections for the first time (Strittmatter 2003). The objective of this study was to histopathological study of H. contortus in Herrick sheep abomasum.

Materials and methods

Study area

The district Urmia of agro-ecological zone was selected for the present study. Climatically, the study region is subtropical and receives an annual rainfall of about 150–350 mm. The temperature is highest in June, before the onset of monsoon season. During summer, the daily maximum temperature exceeds 45 °C and rarely declines below 22 °C. Relative humidity is lowest during April–May and rises during the monsoon season. One year cycle is divided into four seasons viz. winter (December–February) spring (March–April) summer (May–September) and autumn (October–November). Summer also includes monsoon season (July–August)).

Animals and experimental design

During the period from July 2010 to July 2011, a total of 2,421 Herrick sheep ranging from 2 to 5 years of both sexes were subjected to a careful post-mortem examination during abattoir inspection in Urmia slaughterhouses in West Azarbijan province (coordinates: 37°33N, 45°04E) Iran. The Herrick and Afshari sheep were selected to be examined as they are the most important and numerous native breed. The resulting samples were sent to the Laboratory of Parasitology and pathology, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran, for parasitological and histopathological examination.

Parasitological and histopathological analysis

Abomasa of total 2,421 sheeps slaughtered at Urmia abattoir were examined for the presence of adult worm of H. contortus. Sheep were comprising on male (n = 859) and female (n = 1562). Each abomasum was separated from the small intestine and the abomasums transferred to the parasitology laboratory, and examined within 3 h of slaughter. The abomasum was slit open and their contects washed gently with water in separate buckets and collected. In addition, the abomasum was divided longitudinally in two equal parts (towards the greater curvature with a pair of scissors) and the whole mucosa of one part was scraped off and digested in a pepsin–HC1 solution for 10 h at 37 °C. The digest was concentrated over a 400-mesh sieve (aperture diameter 51 pm) under a water-jet and the entire sieve contents examined (Mir et al. 2007; Urquhart et al. 1987). A 10 mm-long sample of the abomasa segment without any injury was removed, fixed, and prepared for histopathological examination. Tissue fragments were fixed in 10 % neutral buffered formalin solution (for 72 h), after stabilizing embedded in paraffin, sectioned at 5 μm thickness and then, stained with hematoxylin and eosin (H&E).

Statistical analysis

Statistical analysis using SPSS software and Chi-square test was applied for the statistical analysis of the data (Petrie and Watson 1999).

Results

Overall prevalence of Haemonchus contortus in sheep

In this study, 225 abomasa (9.3 %) were infected with H. contortus. Sex wise prevalence of H. contortus in sheep was 33.08 % (76/229) in male and 66.22 % (149/225) in female. In the monthly survey, the highest rate of infection was in April (22.9 %) and the lowest was in July (14.9 %). The seasonal survey shows that the highest and lowest infection rates are in the spring (13.6 %) and in summer (2.4 %), respectively. In statistical analysis, there was a significant difference between seasons and the prevalence of the parasite (P < 0.05). The study of parasites in the abomasa of 2,421 sheep revealed that acute and chronic forms of haemonchosis are common in the region. And preacute form of infection has no sign of presence or is utterly rare in above-mentioned region. (Tables 1, 2; Chart 1).

Table 1.

Abomasum monthly infestation with Haemonchus contortus

Seasons Intact Infested Total number of inspections
July
 Count 160 0 160
 Expected count 145.1 14.9 160.0
 Monthly summary (%) 100.0 0 100.0
August
 Count 221 2 223
 Expected count 20.8 223.0
 Monthly summary (%) 202.2 0.9 100.0
99.1 %
September
 Count 231 13 224
 Expected count 221.2 22.8 224.0
 Monthly summary (%) 94.7 5.3 100.0
October
 Count 186 27 213
 Expected count 193.1 19.9 213.0
 Monthly summary (%) 87.3 12.7 100.0
November
 Count 138 18 156
 Expected count 141.4 14.6 156.0
 Monthly summary (%) 88.5 11.5 100.0
December
 Count 158 23 181
 Expected count 164.1 16.9 181.0
 Monthly summary (%) 87.3 12.7 100.0
January 171 11 182
165.0 17.0 182.0
94.0 % 6.0 % 100.0 %
February
 Count 122 10 132
 Expected count 119.7 12.3 132.0
 Monthly summary (%) 92.4 7.6 100.0
March
 Count 73 6 79
 Expected count 71.6 7.4 79.0
 Monthly summary (%) 92.4 7.6 100.0
April
 Count 194 51 245
 Expected count 222.1 22.9 245.0
 Monthly summary (%) 79.2 20.8 100.0
May
 Count 270 58 328
 Expected count 297.4 30.6 328.0
 Monthly summary (%) 82.3 17.7 100.0
June 278
 Count 271 7
 Expected count 252.0 26.0 378.0
 Monthly summary (%) 97.5 2.5 100.0
Total
 Count 2195 226 2421
 Expected count 2195.0 226.0 2421.0
 Monthly summary (%) 90.7 9.3 100.0
Open in a new tab

Table 2.

Abomasum seasonal contamination with Haemonchus contortus

Seasons Intact Infected Total number of inspections
Spring 735 (86.4 %) 116 (13.6 %) 851 (100 %)
Summer 612 (97.6 %) 15 (2.4 %) 627 (100 %)
Autumn 482 (87.6 %) 68 (12.4 %) 550 (100 %)
Winter 366 (93.1 %) 27 (6.9 %) 393 (100 %)
Total 2195 (90.7 %) 226 (9.3 %) 2421 (100 %)
Open in a new tab

Chart 1.

Chart 1

Open in a new tab

Abomasum monthly infestation with Haemonchus contortus

Macroscopic and microscopic findings

Petechial hemorrhage in the abomasal mucosa (Probably due to the attachment of the parasite) (Fig. 1), extensive mucosal hemorrhage, inflammation, mucous secretions around lesions and paleness of internal organs were seen (Fig. 2). Also abomasal contents were fluidal and partially covered with free blood; the carcasses were paled and have generalized edema and fluid throughout of the body cavities secondary to hypoproteinemia. Moreover, following findings were witnessed: mononuclear cells infiltration (lymphocytes, monocytes and plasma cells), prominent eosinophilic infiltration in mucous glands and some even penetrated to the sub mucosa (Fig. 3), perivascular hyperemia and lymphocytic infiltration, tissue thickening due to an increase in mucous glands and mucous secretion (Figs. 4, 5), connective tissue proliferation and necrosis (in chronic abomasal inflammation and wound healing) (Fig. 6).

Fig. 1.

Fig. 1

Open in a new tab

Petechial in the mucosa of the abomasum

Fig. 2.

Fig. 2

Open in a new tab

Hemorrhage in between the glands and inflammatory cell infiltration

Fig. 3.

Fig. 3

Open in a new tab

Infiltration of inflammatory cells in the mucosa of the abomasum

Fig. 4.

Fig. 4

Open in a new tab

Infiltration of inflammatory cells in the mucosa of the abomasum

Fig. 5.

Fig. 5

Open in a new tab

Increase in mucous glands and hemorrhage in between the glands

Fig. 6.

Fig. 6

Open in a new tab

Proliferation of connective tissue

Abomasal pH values and relationship between sex, ages, season and prevalence in sheep

With regard to determination of infected abomasal PH values, slight increase in PH was seen (3.5–4.5), but there wasn’t a close correlation between PH values of parasitized and healthy abomasa (P > 0.05). Also there wasn’t a significant difference between ages of infected sheep (P > 0.05). But the difference between sexes, seasons and abomasal lesions was significant (P > 0.05). Pertaining to seasons in which amount of rainfalls are considerable, temperature would result in dramatic increase of parasite frequency. Subsequently more sheep are afflicted. Needless to say, lesions would be widely seen in the abomasa either. So, there is a direct relevance between season and prevalence of lesions in the abomasa (P < 0.05). And this issue occurs during the spring in the North West region of Iran (West Azerbaijan).

Discussion

The results revealed that the infected animals (sheeps) harbour H. contortus infection throughout the year at all the studied sites with varied incidence. It could be inferred from the infection level that the permanent flocks in azerbaijan west Urmia areas had substantial worm burdens of H. contortus. The present study demonstrated that prevalence of infection was 9.3 % and the average rate of infection is 49 % in Iran (Eslami and Nabavi 1976). So this rate is much less than average of infection in Iran. This is probably due to cold winters and hot summers that destroy the parasite. According to studies by Eslami and Nabavi (1998) rate of infection in sheep is 49 %, and 40.8 % in goats, 0.8 % in wild sheep, 22 % in cattle, and 12 % in camels. The seasonal survey demonstrated that the highest and lowest infection rates are in the spring (13.6 %) and in summer (2.4 %), successively. Recently O’Sullivan and Donald (1970) suggested that spring rise was due to a temporary depression of immunological capacity brought about by endocrine changes associated with lactation, which could result in a resumption of development of arrested larvae, an increased rate of establishment of newly ingested larvae and increased fecundity of female worms. And also in the monthly survey, the highest rate of infection was in April (22.9 %) and the lowest was in July (14.9 %). Thus Gibbs (1967) have demonstrated that transplantation of such arrested larvae into worm-free, susceptible ewes in winter did not result in the immediate maturation of the parasites. When maturation occurred, it coincided with the time that spring rise regularly takes place in this area (April), some IO-12 weeks after transplanting the arrested larvae. Moreover, numerous attempts to induce maturation of arrested larvae in sheep during the winter by administration of immunosuppressive drugs have failed (Brunsdon 1966; McKenna 1998; Nayebzadeh et al. 2005). In the study, there was an increased number of circulating blood eosinophils in the sheeps infected with Haemonchus larvae. This was in agreement with Terefe et al. (2005). There is also some evidence suggesting that eosinophils may contribute to pathogenesis during parasitic infection Nickdel et al. (2001). Moreover, it has previously been shown that a number of ovine parasitic GINs produce a factor(s) that promote eosinophil migration in vitro Wildblood et al. (2005). Yacob et al. (2008) reported the presence of an early and high eosinophilia and migration of the same cellular components into the abomasal and intestinal mucosa in the absence of nematodes in the gut. Many studies have been done on this parasite. Ahmedamir et al. (2007), Zacharias et al. (2008), Scott et al. (1999) are reviewed pathophysiology of haemonchosis. Also Ameen et al. (2006), Wilson et al. (1996) reported hematologic changes. Nayebzadeh et al. (2005), Troell et al. (2005) studied at parasite growth stages and its changes. In Anderson (2000) studies, weight loss is reported during the chronic infection with this parasite in sheep. Zacharias et al. (2008) reported anemia in merino sheep. Also, Courtney et al. (1984), Nayebzadeh et al. (2005) reported it too. Additionally in microscopic examination by Nayebzadeh et al. (2005), proliferation of macrophages and fibroblasts and infiltration of lymphocytes and eosinophils have seen around the adult worms in pyloric region. Moreover, in another study by Scott et al. (1999), fundus region thickening was seen, that caused by mucous cells hyperplasia. Also Mir et al. (2007) reported that lymphocytes from both naive lambs and immune sheep responded to a similar spectrum of molecular and also this report therefore supports the findings of Anthony et al. (2007, 2008) who had suggested that lymphocyte proliferative responses in naive sheep were important in innate resistance to this parasite weight fraction in soluble antigen. These observations suggest that the chronic nature of primary H. contortus nematode infections may be due to a change in the type of immune response induced by larval and adult nematodes and that the adult nematodes may actively subvert the initial immune response induced after infection.

References

  1. Ahmedamir R, Zahoor Chishti M, Afzalzargar M. Clinicopathological changes in sheep experimentally infected with Haemonchus contortus. World J Agric Sci. 2007;3(5):562–566. [Google Scholar]
  2. Amarante AFT, Bricarello PA, Huntley JF, Mazzolin LP, Gomes JC. Relationship of abomasal histology and parasite-specific immunoglobulin a with resistance to Haemonchus contortus infection in three breeds of sheep. Vet Parasitol. 2005;128:99–107. doi: 10.1016/j.vetpar.2004.11.021. [DOI] [PubMed] [Google Scholar]
  3. Amarante AFT, Susin I, Rocha RA, Silva MB, Mendes CQ, Pires AV. Resistance of Santa Ines and crossbred ewes to naturally acquired gastrointestinal nematode infections. Vet Parasitol. 2009;165:273–280. doi: 10.1016/j.vetpar.2009.07.009. [DOI] [PubMed] [Google Scholar]
  4. Ameen SA, Josua RA, Ige OA. Experimental studies on gastro-intestinal nematode infection;clinical observations and haematological changes following Haemonchus contortus infection in west African dwarf (WAD) kids. J Anim Vet Adv. 2006;5(6):511–514. [Google Scholar]
  5. Anderson GS. Minimum and maximum development rates of some forensically important Calliphoridae (Diptera) J Forensic Sci. 2000;45:824–832. [PubMed] [Google Scholar]
  6. Anthony RM, Rutitzky LI, Urban JF, Gause WC. Protective immune mechanisms in helminth infection. Nat Rev Immunol. 2007;7(12):975–987. doi: 10.1038/nri2199. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Anthony R, McMaster D, Sangster N. Haemonchus contortus infection in sheep:parasite fecundity correlates with worm size and host lymphocyte counts. Vet Parasitol. 2008;153:285–293. doi: 10.1016/j.vetpar.2008.01.040. [DOI] [PubMed] [Google Scholar]
  8. Brunsdon RV. The immunity of sheep to trichostrongyle infestations following reduction of the circulating leucocyte count by oral administrations of chlorambucil. A further study of the spring phenomenon. NZ Vet J. 1966;14:161–162. doi: 10.1080/00480169.1966.33661. [DOI] [PubMed] [Google Scholar]
  9. Burke JM, Kaplan RM, Miller JE, Terrill TH, Getz WR, Mobini S, Valencia E, Williams MJ, Vatta AF. Accuracy of the FAMACHA system for on-farm use by sheep and goat producers in the southeastern US. Vet Parasitol. 2007;147:89–95. doi: 10.1016/j.vetpar.2007.03.033. [DOI] [PubMed] [Google Scholar]
  10. Courtney CH, Parker CF, McClure KE, Herd RP (1984) A comparison of the periparturient rise in fecal egg counts of exotic and domestic ewes. Int J Parasitol 14:377–381 [DOI] [PubMed]
  11. Eslami A, Nabavi L. Species of gastro-intestinal nematodes of sheep from Iran. Bull Soc Pathol Exot Filiales. 1976;69(1):92–95. [PubMed] [Google Scholar]
  12. Eslami AH, Nabavi L (1998) Species of gastro-intestinal nematodes of sheep from Iran. Bull Soc Pathol Exot Filiales 69:92–95 [PubMed]
  13. Gibbs HC (1967) Some factors involved in the “spring rise” phenomenon in sheep. N.G. Elwert Universitatus und Verlags buch hand lung, Marburg/Lund
  14. Kemper KE, Elwin RL, Bishop SC, Goddard ME, Woolaston RR. Haemonchus contortus and Trichostrongylus colubriformis did not adapt to long-term exposure to sheep that were genetically resistant or susceptible to nematode infections. Int J Parasitol. 2009;39:607–614. doi: 10.1016/j.ijpara.2008.08.013. [DOI] [PubMed] [Google Scholar]
  15. McKenna PB. The effect of previous cold storage on the subsequent recovery of infective third stage nematode larvae from sheep faeces. Vet Parasitol. 1998;80:167–172. doi: 10.1016/S0304-4017(98)00203-9. [DOI] [PubMed] [Google Scholar]
  16. Mir RA, Chishti MA, Zargar H, Ganie SA. Clinicopathological changes in sheep experimentally infected with Haemonchus contortus World. J Agric Sci. 2007;3(5):562–566. [Google Scholar]
  17. Nayebzadeh H, Seyfiabadshapouri M, Hoghooghi N (2005) Immunization of Arabian sheep against haemonchosis with Haemonchus contortus intestinal homogenate 15th European congress of Clinical Microbiology and Infectious Diseases(ECCMID), 02 April 2005–05 April 2005
  18. Nickdel MB, Roberts F, Brombacher F, Alexander J, Roberts CW (2001) Counter-protective role for interleukin-5 during acute Toxoplasma gondii infection. Infect Immun 69:1044–1052 [DOI] [PMC free article] [PubMed]
  19. O'Sullivan BM, Donald AD (1970) A field study of nematode parasite populations in the lactating ewe. Parasitology 61:301–315 [DOI] [PubMed]
  20. Petrie A, Watson P. Statistics for veterinary and animal sciences. London: Blackwell; 1999. [Google Scholar]
  21. Piedrafita D, Raadsma HWR, Gonzalez JF, Meeusen ENT. Increased production through parasite control: can ancient breeds of sheep teach us new lessons? Trends Parasitol. 2010;26:568–573. doi: 10.1016/j.pt.2010.08.002. [DOI] [PubMed] [Google Scholar]
  22. Scott I, Dick A, Irvine J, Stear MJ, Mckellar QA. The distribution of pepsinogen within the abomasal of cattle and sheep infacted with ostertagia spp. and sheep infected with Haemonchus contortus. Vet Parasitol. 1999;82:145–159. doi: 10.1016/S0304-4017(99)00006-0. [DOI] [PubMed] [Google Scholar]
  23. Strittmatter K. Schafzucht. Stuttgart: Eugen Ulmer Verlag; 2003. [Google Scholar]
  24. Terefe G, Yacob HT, Grisez C, Prevot F, Dumas E. Haemonchus contortus egg excretion and female length reduction in sheep previously infected with Oestrus ovis (Diptera: Oestridae) larvae. Vet Parasitol. 2005;128:271–283. doi: 10.1016/j.vetpar.2004.11.036. [DOI] [PubMed] [Google Scholar]
  25. Troell K, Waller P, glund J. The development and over winter in survival of free-living larvae of Haemonchus contortus in Sweden. J Helminthol. 2005;79:373–379. doi: 10.1079/JOH2005286. [DOI] [PubMed] [Google Scholar]
  26. Urquhart GM, Duncan JL, Dunn AM, Jennings FW (1987) Veterinary parasitology. English Language Book Society, London
  27. Wildblood LA, Kerr K, Clark DA, Cameron A, Turner DG. Production of eosinophil chemo attractant activity by ovine gastrointestinal nematodes. Vet Immunol Immunopathol. 2005;107:57–65. doi: 10.1016/j.vetimm.2005.03.010. [DOI] [PubMed] [Google Scholar]
  28. Wilson AG, Thake DC, Heydens WE, Brewster DW, Hotz KJ (1996) Mode of action of thyroid tumor formation in the male Long–Evans rat administered high doses of alachlor. Fundam Appl Toxicol 3:16–23 [DOI] [PubMed]
  29. Yacob HT, Basazinew BK, Basu AK. Experimental concurrent infection of Afar breed goats with Oestrus ovis (L1) and Haemonchus contortus (3): interaction between parasite populations, changes in parasitological and basic haematological parameters. Exp Parasitol. 2008;120:180–184. doi: 10.1016/j.exppara.2008.07.006. [DOI] [PubMed] [Google Scholar]
  30. Zacharias F, Guimaraes JE, Araujo PR, Almeida MAO. Effact of homeopathic medicine on helminth parasitism and resistance of Haemancus contortus infected sheep. Homeopathy. 2008;97:145–151. doi: 10.1016/j.homp.2008.05.004. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Parasitic Diseases: Official Organ of the Indian Society for Parasitology are provided here courtesy of Springer

RESOURCES