Background: Trichuriasis is an important soil-transmitted helminth infection caused by Trichuris trichiura. About one-tenth of the world population may be infected. Incidentally, T. vulpis or dog whipworm has been reported to infect humans based on the egg size. However, an overlapping egg dimension occurs between T. trichiura and T. vulpis leading to the potential for misdiagnosis. Objective: Develop a PCR method to differentiate T. trichiura and T. vulpis eggs in stool samples and to investigate the prevalence of both whipworms in humans and dogs in a rural community in Thailand. Materials and methods: We determined and compared the small subunit ribosomal RNA sequences of both species of whipworms for developing species-specific PCR diagnosis. After validation of the method, we conducted a cross-sectional survey at Ta Song Yang District in Tak Province, northwestern Thailand in 2008. Stool samples were randomly recruited from 80 schoolchildren (36 males, 44 females) and 79 dogs in this community. Results: Fifty-six individuals harbored Trichuris eggs in their stools. The PCR-based diagnosis revealed that 50 cases were infected with T. trichiura and six (10.7%) were co-infected with both T. trichiura and T. vulpis. Although the dimension of Trichuris eggs provided some diagnostic clues for species differentiation, a remarkable variation in the length of these whipworm eggs was observed among samples that could lead to misdiagnosis. Conclusion: Both T. trichiura and T. vulpis eggs were detected in stool samples of dogs that roamed around this community, highlighting the potential reservoir role of dogs in the transmission of both human and dog whipworms in this population.
1. Bethony J, Brooker S, Albonico M, Geiger SM, Loukas A, Diemert D, Hotez PJ. Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. Lancet. 2006; 367:1521-32.
2. Albonico M, Chwaya HM, Montresor A, Stolfzfus RJ, Tielsch JM, Alawi KS, Savioli L. Parasitic infections in Pemba Island school children. East Afr Med J. 1997; 74:294-8.
3. Hadju V, Abadi K, Stephenson LS, Noor NN, Mohammed HO, Bowman DD. Intestinal helminthiasis, nutritional status, and their relationship; a crosssectional study in urban slum school children in Indonesia. Southeast Asian J Trop Med Public Health. 1995; 26:719-29.
4. Needham C, Kim HT, Hoa NV, Cong LD, Michael E, Drake L, Hall A, Bundy DA. Epidemiology of soiltransmitted nematode infections in Ha Nam Province, Vietnam. Trop Med Int Health. 1998; 3:904-12.
5. Norhayati M, Zainudin B, Mohammod CG, Oothuman P, Azizi O, Fatmah MS. The prevalence of Trichuris, Ascaris and hookworm infection in Orang Asli children. Southeast Asian J Trop Med Public Health. 1997; 28: 161-8.
6. Stephenson LS, Latham MC, Kurz KM, Kinoti SN, Brigham H. Treatment with a single dose of albendazole improves growth of Kenyan schoolchildren with hookworm, Trichuris trichiura, and Ascaris lumbricoides infections. Am J Trop Med Hyg. 1989; 41:78-87.
7. Layrisse M, Aparcedo L, Martinez-Torres C, Roche M. Blood loss due to infection with Trichuris trichiura. Am J Trop Med Hyg. 1967; 16:613-9.
8. Ramdath DD, Simeon DT, Wong MS, Grantham- McGregor SM. Iron status of schoolchildren with varying intensities of Trichuris trichiura infection. Parasitology.1995; 110:347-51.
9. Robertson LJ, Crompton DW, Sanjur D, Nesheim MC. Haemoglobin concentrations and concomitant infections of hookworm and Trichuris trichiura in Panamanian primary schoolchildren. Trans R Soc Trop Med Hyg. 1992; 86:654-6.
11. Cooper ES, Bundy DA, Henry FJ. Chronic dysentery, stunting, and whipworm infestation. Lancet. 1986; 8501:280-1.
12. Nokes C, Bundy DA. Does helminth infection affect mental processing and educational achievement? Parasitol Today. 1994; 10:14-8.
13. Watkins WE, Pollitt E. Stupidity or worms: do intestinal worms impair mental performance? Psychol Bull. 1997; 121:171-91.
14. Chan MS. The global burden of intestinal nematode infections: fifty years on. Parasitol Today. 1997; 13: 438-43.
15. Murray CJL, Lopez AD. The global burden of disease: a comprehensive assessment of mortality and morbidity from disease, injuries, and risk factors in 1990 and projected to 2020. 1st ed. Cambridge (MA): Harvard University Press; 1996.
16. World health report: Annex Table 2: Deaths by cause, sex, and mortality stratum in WHO regions. World Health Organization; 2002.
17. Bundy DA, Cooper ES. Trichuris and trichuriasis in humans. Adv Parasitol. 1989; 28:107-73.
19. Dunn JJ, Columbus ST, Aldeen WE, Davis M, Carroll KC. Trichuris vulpis recovered from a patient with chronic diarrhea and five dogs. J Clin Microbiol. 2002; 40:2703-4.
20. Kenney M, Yermakov V. Infection of man with Trichuris vulpis, the whipworm of dogs. Am J Trop Med Hyg. 1980; 29:1205-8.
21. Yoshikawa H, Yamada M, Matsumoto Y, Yoshida Y. Variations in egg size of Trichuris trichiura. Parasitol Res. 1989; 75:649-54.
22. Lovis L, Mak TK, Phongluxa K, Soukhathammavong P, Sayasone S, Akkhavong K, et al. PCR diagnosis of Opisthorchis viverrini and Haplorchis taichui infections in a Lao Community in an area of endemicity and comparison of diagnostic methods for parasitological field surveys. J Clin Microbiol. 2009; 47:1517-23.
23. Mayta H, Gilman RH, Prendergast E, Castillo JP, Tinoco YO, Garcia HH, et al. Cysticercosis Working Group in Peru. Nested PCR for specific diagnosis of Taenia solium taeniasis. J Clin Microbiol. 2008; 46:286-9.
24. Putaporntip C, Hongsrimuang T, Seethamchai S, Kobasa T, Limkittikul K, Cui L, et al. Differential prevalence of Plasmodium infections and cryptic Plasmodium knowlesi malaria in humans in Thailand. J Infect Dis. 2009; 199:1143-50.
25. Traub RJ, Macaranas J, Mungthin M, Leelayoova S, Cribb T, Murrell KD, et al. A new PCR-based approach indicates the range of Clonorchis sinensis now extends to central Thailand. PLoS Negl Trop Dis. 2009; 3:e367.
26. Cutillas C, de Rojas M, Ariza C, Ubeda JM, Guevara D. Molecular identification of Trichuris vulpis and Trichuris suis isolated from different hosts. Parasitol Res. 2007;100:383-9.
27. Martinez EM, Correia JA, Villela EV, Duarte AN, Ferreira LF, Bello AR. Random amplified polymorphic DNA analysis of DNA extracted from Trichuris trichiura (Linnaeus, 1771) eggs and its prospective application to paleoparasitological studies. Mem Inst Oswaldo Cruz. 2003; 98:S59-62.
28. Oliveros R, Cutillas C, de Rojas M, Arias P. Characterization of four species of Trichuris (Nematoda: Enoplida) by their second internal transcribed spacer ribosomal DNA sequence. Parasitol Res. 2000; 86:1008-13.
29. Tamura K, Nei M, Kumar S. Prospects for inferring very large phylogenies by using the neighbor-joining method. Proc Natl Acad Sci USA. 2004; 101:11030-5.
30. Librado P, Rozas J. DnaSP v5: a software for comprehensive analysis of DNA polymorphism data. Bioinformatics. 2009; 25:1451-2.
31. Garcia LS. Macroscopic and microscopic examination of fecal specimens. In: Garcia LS, editor. Diagnostic Medical Parasitology 4th ed. Washington, DC: ASM Press; 2001. p.741-85.
32. Masuda Y, Kishimoto T, Ito H, Tsuji M. Visceral larva migrans caused by Trichuris vulpis presenting as a pulmonary mass. Thorax. 1987; 42:990-1.
33. Sakano T, Hamamoto K, Kobayashi Y, Sakata Y, Tsuji M, Usui T. Visceral larva migrans caused by Trichuris vulpis. Arch Dis Child. 1980; 55:631-3.
34. Coulter JB, Jewsbury JM, Beesley WN, Bailey W. Visceral larva migrans and Trichuris vulpis. Arch Dis Child. 1981; 56:406.
35. Kradin RL, Badizadegan K, Auluck P, Korzenik J, Lauwers GY. Iatrogenic Trichuris suis infection in a patient with Crohn disease. Arch Pathol Lab Med. 2006; 130:718-20.
36. Duenngai K, Sithithaworn P, Rudrappa UK, Iddya K, Laha T, Stensvold CR, et al. Improvement of PCR for detection of Opisthorchis viverrini DNA in human stool samples. J Clin Microbiol. 2008; 46:366-8.
37. Inpankaew T, Traub R, Thompson RC, Sukthana Y. Canine parasitic zoonoses in Bangkok temples. Southeast Asian J Trop Med Public Health. 2007; 38: 247-55.
38. Rinaldi L, Biggeri A, Carbone S, Musella V, Catelan D, Veneziano V, et al. Canine faecal contamination and parasitic risk in the city of Naples (southern Italy). BMC Vet Res. 2006; 2:29.
39. Traub RJ, Robertson ID, Irwin P, Mencke N, Thompson RC. The role of dogs in transmission of gastrointestinal parasites in a remote tea-growing community in northeastern India. Am J Trop Med Hyg. 2002; 67: 539-45.
40. Jansen J. Abnormal eggs of Trichuris ovis (Abildgaard 1795) (Nematoda: Trichuridae). Z Parasitenkd. 1984; 70:827-8.
41. Elliott DE, Summers RW, Weinstock JV. Helminths and the modulation of mucosal inflammation. Curr Opin Gastroenterol. 2005; 21:51-8.