Parasitic flagellates, host-pathogen relationships and protective strategies
"To strive, to seek, to find, and not to yield" - Alfred Tennyson

Patrick TK Woo (U of G profile)
University Professor Emeritus
University of Guelph (U of G)
Guelph, Ontario, Canada

Short Curriculum Vitae
Research Overview and Programs

Email: pwoo@uoguelph.ca
Office: Room 2443, Summerlee Science Complex

I. Major Research and Academic Appointments
I (a) Research Appointments (sponsor*): before 1974

Postdoctoral Fellow (Medical Research Council*), Ballard Fellow (OVC*), and Associated Faculty @ Ontario Veterinary College, U of G, Canada
Andre Mayer Research Fellow (FAO, UN*) @ East African Trypanosomiasis Research Organization, Uganda, and @ Serengeti Research Institute, Tanzania
IDRC Research Fellow and Consultant, and Visiting Scientist (IDRC*) @ Nigerian Institute for Trypanosomiasis Research, Nigeria

I (b) Academic Appointments: @ University of Guelph
Assistant Professor (1974),Associate Professor (1978),Professor (1984).
Professor, Collaborative International Development Studies (1993).
Director, Axelrod Institute of Ichthyology (2002).
University Professor Emeritus (elected by Senate; 2005);conferred at convocation by The Honourable LM Alexander, Chancellor.

I (c) External Appointments: Academic;Research;Consultant;Examiner or Assessor

II. Research: programs;associated activities;parasitic flagellates and diseases

III. Publications:books;book chapters;review articles; research papers

IV. Excerpts from Reviews: on selected fish disease/disorder books

V. Founder and Organizer: The Roy C Anderson Memorial Lecture in Parasitology

VI. Presentations:invited lectures @ conferences/universities;contributed papers @ conferences

VII. Databases:PubMed;ResGate; LinkedIn; MicrosoftAcademic; GoogleScholar; SemanticScholar


II. Research:
II (a). Programs

Patrick has always focused his research on parasitic flagellates which include those of medical and economic importance. His external academic and research appointments (including travel and living expenses) were funded by international and/or national agencies in numerous ways (e.g. as visiting professor, research fellow, assessor of academic programs and/or promotions, research consultant), and these generous sponsorships had allowed him to work and/or interact with colleagues in Africa, Asia, Europe, and North and South America. He had presented numerous lectures at conferences and universities, and they were sponsored by their respective hosts. Patrick was research consultant, external examiner/assessor, and active in the scientific community. Over the years he had developed three research programs (sections A and B), and had also initiated a couple of 'infectious disease' related activities (section C) which were well received.

A. His first research program was on trypanosomes and trypanosomiasis (Program I), and a major component of his research in Africa was on the diagnosis of human trypanosomiasis. He successfully used the Haematocrit Centrifuge Technique (HCT; Woo, 1969) to detect trypanosomes in the blood and cerebral spinal fluid of patients suffering from either Rhodesian or Gambian trypanosomiasis. The study was conducted at the hospital attached to the East African Trypanosomiasis Research Organization (EATRO) in Uganda (Woo, 1970). He adapted HCT for use under field conditions and conducted a survey in the Lugala area, Uganda; 413 people were examined in a single day, and trypanosomes were detected in one person (with no clinical signs of the disease) and microfilariae in 17 other people (Woo, 1971). Feasibility of HCT as a field technique was confirmed in a larger survey on human trypanosomiasis in Musoma district, Tanzania (Onyango & Woo, 1971).

Woo & Kauffmann (1971) showed that HCT could also be used as a field technique to detect low virulent strains of Trypanosoma congolense in wild animals (e.g. lions); this was part of a field study to determine the epidemiology of animal trypanosomiasis in the Serengeti National Park. Tanzania. HCT is a rapid and sensitive technique for the detection of trypanosomes (Trypanosoma brucei brucei, T. brucei rhodesiense,T. evansi, T. congolense) under laboratory conditions (Woo & Rogers, 1974), and it is frequently used/cited in studies on trypanosomes and trypanosomiasis (e.g. in Google Scholar, Semantic Scholar).

B. He developed two other research programs in 1974 after his academic appointment at the University. The two programs with contributions from highlydedicated and talented collaborators (e.g. graduate students, postdoctoral fellows) had enjoyed continuous NSERC support, and also sponsorships from international and/or national agencies (e.g. Networks of Centre of Excellence of Canada) since their inceptions.
Program II was on the biology, systematics and taxonomy of parasitic flagellates (e.g. Giardia, Trypanosoma) in fish, amphibian, avian, and mammalian hosts. The research included descriptions of several new species and re-descriptions of named flagellates, their transmissions and distributions, basic biology and host-parasite relationships.
Program III was on fish pathogen/disease (e.g. Cryptobia). Briefly, Woo (1979) described and characterized a disease caused by the haemoflagellate, Cryptobia (Trypanoplasma) salmositica (satisfied Koch's postulates) in infected rainbow trout. He subsequently established, developed and maintained a multidisciplinary research program to better understand the pathogen and the disease process so as to develop 'proof-of-concepts' strategies against the pathogen and disease (see below - subsections i - iv).The pathogen has been reported from all species of Pacific salmon and is transmitted by the freshwater leech, Piscicloa salmositica in streams and rivers on the west coast of North America.

Cryptobia and cryptobiosis is a major component of his fish pathogen/disease program, and its four areas of emphases are:
(i) biology of the pathogen (e.g. transmission;ultrastructure; nutritional requirements; respiration and related enzymes; glucocorticoid receptors)
(ii) host-parasite relationships (e.g. clinical signs and pathophysiology of the disease; mechanisms of the anemia, and anorexia; host's stress hormone stimulates Cryptobia multiplication;innate protection in Cryptobia-resistant and Cryptobia-tolerant salmonids; adaptive protection in Cryptobia-susceptible salmonids)
(iii) cryptobiosis (e.g. clinical signs; histopathology; disease mechanism including identification metalloprotease (200 kDa) as the disease-causing factor; isolation, purification, characterization and sequence the metalloprotease gene)
(iv) ‘proof-of-concept’ strategies against the pathogen/disease (e.g. a therapeutic monoclonal antibody that also inhibits parasite aerobic respiration and multiplication; breeding of Cryptobia-resistant and Cryptobia-tolerant salmonids; a protective attenuated vaccine and a DNA vaccine against the pathogen; chemo and immuno-chemotherapy of infected fish).

C. Although his research is on parasitic flagellates and diseases he is also interested in other areas of inquiry which include studies on pathogenic viruses and bacteria of animals; for example, he founded The Roy C Anderson Memorial Lecture in Parasitology in 2001, and organised the lecture series from inception till 2016. Numerous eminent scientists including a Nobel Laureate had accepted his invitation to present their research on 'infectious diseases' and to interact with students, staff and faculty at UofG. Patrick always learn from his collaborators, especially from colleagues who have expertise in unrelated disciplines. He and several colleagues had also edited a number of well-received multidisciplinary books on diseases and disorders of fish - excerpts from reviews on selected books.


II (b). Parasites: Trypanosoma, Cryptobia, Giardia and Spironucleus

Parasitic flagellates (Figs. 1 - 3 & 7) of vertebrates including those that cause disease in humans (Fig. 2) and other animals (Figs. 3b & 7). His research before UofG appointment included studies on trypanosomes (Figs. 1 & 2), and mammalian trypanosomiasis which involved field studies in East and West Africa (Figs. 4 - 6).

Fig. 1: Trypanosoma ranarum in Rana pipiensFig. 2: Trypanosoma b. rhodesiense in Homo sapiensFig, 3a: Giardia microti in Microtus pennsylvanicusFig. 3b: Spironucleus sp. in Oncorhynchus tschawytscha

He also worked on human and small mammal Giardia spp. (Fig. 3a) after his academic appointment at U of G (profile). His program on Cryptobia (Fig. 7) and cryptobiosis (Figs. 8-10) was initiated in 1974 and it included the development of 'proof-of-concept' protective strategies. The program has/had continuous NSERC and other fundings since its inception. Cryptobia salmositica (Fig. 7) has been recorded from all species of Pacific salmon (Oncorhynchus spp.) on the west coast of North America, and it is transmitted by the freshwater leech (Piscicola salmositica) in streams and rivers.
Another component of his research program is on systemic spironucleosis; outbreaks of the disease have been reported in salmonids cultured in sea cages in Canada and Norway. Large numbers of Spironucleus (Fig. 3b) are in the blood, internal organs, and ulcers on the body surface (Figs. 11-13) of infected fish. The pathogen is transmitted directly between fish.

II (c). Diseases: Trypanosomiasis, Cryptobiosis and Spironucleosis

African Trypanosomiases [Figs. 2 & 4 - 6]

Fig. 4: Human trypanosomiasis (Trypanosoma brucei gambiense), EATRO, Uganda

Fig. 5: Haematocrit Centrifuge Technique, trypanosomiasis survey (human), SRI, Tanzania

Fig. 6: Bovine trypanosomiasis (Trypanosoma congolense), EATRO, Uganda


One of his early contributions on human
trypanosomiasis in Africa was to use the Haematocrit Centrifuge Technique (HCT; Woo, 1969) to detect trypanosomes in the blood and cerebral spinal fluid of patients admitted to the hospital at the East African Trypanosomiasis Organization (EATRO) in Uganda (Woo, 1970). He adapted HCT for use under field conditions and conducted a survey in the Lugala area, Uganda; 413 people were examined in a single day, and trypanosomes were detected in one person (with no clinical signs of the disease) and microfilariae in 17 other people (Woo, 1971). Feasibility of HCT as a field technique was confirmed in a larger survey on human trypanosomiasis in Musoma district, Tanzania (Onyango & Woo, 1971).

"The . . . technique of Woo is the most suitable for rural hospitals" (Foulkes, 1981). It " . . . is still in use in many HAT [Human African Trypanosomiasis] control programs" in Africa (Chappuis et al., 2005) , and " . . . is the test of choice since it concentratestrypanosomes at the buffy coat area where they can be located by microscopy" (Matovu E. et al. 2012).
HCT is also used to diagnose human African trypanosomiasis outside Africa (e.g. Lejon et al., 2003), for the detection of congenital Trypanosoma cruzi infection in Argentina (Moretti et al. 2005), and it is ". . . recommended for the parasitological diagnosis of acute Chagas' disease and malaria" in rural Bolivia (Fuente et al., 1985).

Woo & Kauffmann (1971) showed that HCT could also be used as a field technique to detect low virulent strains of Trypanosoma congolense in wild animals (e.g. lions); this was part of a field study to determine the epidemiology of trypanosomiasis in the Serengeti National Park. Tanzania. HCT is a rapid and sensitive technique for the detection of trypanosomes (Trypanosoma brucei brucei, T. brucei rhodesiense, T. evansi, T. congolense) under laboratory conditions (Woo & Rogers, 1974) and it is " . . . most commonly used for the diagnosis of animal trypanosomiasis . . . " (Desqquesnes & Tresse 1996). It is recommended by the‘International Office of Epizootics' (OIE 2013 - Table 1), and Moti et al. (2014) confirms that "HCT remains a robust field method as it will be more efficient than PCR to detect clinical cases that have to be treated". The technique can also be used to determine the effectiveness of chemotherapy against trypanosomiasis (e.g. Sekoni & Rekwot 2003).

The Haematocrit Centrifuge Technique is frequently used/cited in studies on trypanosomes and trypanosomiasis (e.g. in Google Scholar, Semantic Scholar), and it is sometimes also called the:
"Woo test", e.g. (i) Chappuis F et al. 2005,Options for field diagnosis of human African trypanosomiasis. Clinical Microbiol. Reviews 18: 133-146
    (ii) Desquesnes M & Tresse L1999, Sensitivity of the Woo test for detection of Trypanosoma vivax. Proceedings of First Symposium o New World Trypanosomes, pp. 76-81.
"Woo technique", e.g.(i) Quispe AP et al. 2003, Prevalencia de Trypanosoma vivax en bovinos de cuatro distritos de la provincia de Coronel Portillo, Ucayali. Rev investig. vet. Peru 14: 161-165
    (ii) Cadioli FA et al. 2012First report of Trypanosoma vivax outbreak in dairy cattle in Sao Paulo, Brazil. Rev. Bras. Parasitol. Vet. Sao Paulo 21: 118-124
"Woo method", e.g. (i) Uilenberg G 1998, Chapter 3 - Diagnosis. In: A field guide for the diagnosis, treatment and prevention of African animal trypanosomosis, FAO, UN, 158 pages
    (ii) OIE 2013, Chapter 2.4.17 - Trypanosomosis (tsetse-transmitted). In: OIE Terrestrial Manual, pp. 1-11.

(b) Salmonid Cryptobiosis [Figs. 7 - 10]
Complete list of papers on
Cryptobia and cryptobiosis

Fig. 7: Cryptobia (T.) salmositica with a red cell from an anemic fishFig. 8: Bilateral exophthalmia in acute salmonid cryptobiosis
Fig. 9: Splenomegaly (6 - 8 times by volume)Fig. 10: General edema and abdominal distension with ascites
Salmonid cryptobiosis is caused by the hemoflagellate, Cryptobia salmositica (Figs. 7-10; Woo, 2003). The parasite is transmitted by leeches (Piscicola salmositica)in streams and rivers on the Pacific coast of North America; however, direct transmission can also occur when infected and uninfected fish are held for prolonged periods in the same tank or under certain hatchery conditions.Clinical signs include anorexia, exophthalmia (Fig.8), splenomegaly (Fig. 9), hepatomegaly, general edema and abdominal distention with ascites (Fig. 10), a microcytic hypochromic anemia,and red cells are antiglobulin positive. Infected salmonids are susceptible to hypoxia, and their metabolism and swimming performance are reduced. Also, the lytic activities of complement in sera of infected fish are reduced, and the ability of infected fish to mount a protective response against a secondary pathogen and/or antigen is depressed. The anemia and anorexia in infected fish contribute to the immunodepression. Cryptobia has two proteases - the cysteine protease is a metabolic enzyme while metalloprotease (a histolytic enzyme) is the main virulent factor.

The program on cryptobiosis is a multidisciplinary study. It is on the biology of the pathogen, diagnosis of infection, pathobiology in cryptobiosis including elucidation of the disease mechanism, host immune responses, and the development of proof-of-concept strategies against the parasite and disease (Woo, 2003). Preventive strategies include exploiting innate and adaptive immunity, chemotherapy and immunochemotherapy (Woo, 2010).

Gene Sequences of Cryptobia salmositica in GENBANK
(1) Jesudhasan, P.R.R. & P.T.K. Woo (2004) Methionine adenosyltransferase gene. GENBANK No. AY603961.
(2) Jesudhasan, P.R.R. & P.T.K. Woo (2004) Major surface glycoprotein metalloproteinase gene - key gene involved in pathogensis. GENBANK No. AY632692.
(3) Jesudhasan, P.R.R. & P.T.K. Woo (2004) Cysteine proteinase gene. GENBANK No. AY713477.

(c) Salmonid Spironucleosis [Figs. 3b & 11-13]
Systemic spironucleosis is caused by Spironucleus (
Fig. 3b) - the parasite is in the blood and internal organs of salmonids. The parasite causes morbidity and mortality in fishes and there have been outbreaks of the disease in salmon cultured in sea cages - in chinook salmon on the west coast of Canada and in Atlantic salmon in Norway. Fish mortality was high and some infected chinook salmon had abdominal distensions and were anemic while infected Atlantic salmon were significantly smaller than healthy fish and they behaved'abnormally' prior to death. Little is known about the biology of the pathogen nor factors that precipitated outbreaks, and there are no preventive nor control strategies against the parasite and disease (Woo, 2006. Chapter 3. In:
Fish Diseases and Disorders, Vol. 1: Protozoan and Metazoan Infections, 2nd ed., pp. 46-114).

Fig. 11: Unilateral exophthalmiaFig. 12: Ulceration on body surfaceFig. 13: Globulated and enlarged spleen

Spironucleus barkhanus has a blood and a tissue phase in experimentally infected Atlantic salmon. It first appears in the blood about a week after infection in some fish and the parasitaemia peaks at six weeks. The parasite is not detectable in the blood at about eight weeks after infection but it occurs in high numbers in the spleen, liver, eye socket, and muscles.Thirty eight out of 40 infected fish died in one experiment, and mortality was equally high (29 out of 30 infected fish) in another experiment with Atlantic salmon from three fish families. Clinical signs of the disease include unilateral exophthalmia (Fig. 11), skin blisters and ulcerations (Fig. 12), enlarged and globulated spleens (Fig. 13), livers with whitish/yellowish nodules, and haemorrhages in organs. The parasite can be experimentally transmitted via inoculation of infected blood or through co-habitation of infected and uninfected fish (Guo & Woo, 2004).

Sharing a joke before the 2006 Spring Convocation Ceremony

Prof. M.J. Emes, CBS Dean; Prof. P.T.K. Woo; The Hon. L.M. Alexander, Chancellor
Prof. A.J.S. Summerlee, President and Vice Chancellor; Prof. M.M. Ferguson, DIB Chair

____________________
Updated: June 1, 2015