PRACTICAL PARASITOLOGY Peer Reviewed

Practical Parasitology COMMON QUESTIONS THAT VETERINARIANS ASK PARASITOLOGY EXPERTS Byron L. Blagburn, MS, PhD, Diplomate ACVM (Hon) Auburn University

Veterinarians in practice often have numerous tell veterinarians that you can purchase a good questions about how to address the parasites microscope and centrifuge with needed accessories affecting their patients. To answer these questions, for less than several other pieces of in-clinic they often rely on the advice of experts. This series diagnostic equipment. They will likely last you a is intended to address parasite problems that practice lifetime with little or no maintenance or veterinarians must manage in everyday practice. repair. To initiate the series, I have compiled a short list of common questions that I receive from Training Staff veterinarians in the practice trenches. Hopefully, Interested and enthusiastic staff can learn the my answers can address some questions before you more common parasitology tests and procedures have to ask them. very quickly and can become very good at it. I have a staff member who oversees my daily 1. Should I perform fecal examinations, gross diagnostics that, when fi rst hired, knew nothing parasite diagnostics, heartworm tests, and about parasite diagnosis. She is now among the tests for vector-borne diseases in the clinic or best in our fi eld. Given the wet labs available at send them to an outside laboratory? continuing education meetings and resources and The answer to this question depends on several counsel provided by academic laboratories and test factors: manufacturers, training and experience are easily • Do you have the necessary equipment and obtained. Most of us in academic laboratories are supplies in place or are you willing to acquire more than willing to offer training suggestions them? and resources to interested and enthusiastic staff • Do you have trained staff with the skills to members. perform the tests? • How often are you called upon to perform these Number of Tests tests and how many tests will be run? Regarding the number of tests performed, when • Do you have convenient access to a reference or staff are trained and the procedures are in place, academic laboratory? the number of specimens to be processed is of less • Do cost and turnaround time factor into your concern. Once the decision is made to proceed decision? with resident diagnostics, it is just a matter of time Reference and academic laboratories provide before the system is performing effi ciently. excellent parasitology resources for the practicing veterinarian. However, the conduct of in-clinic Reference Laboratories diagnostic testing is worthy of consideration. If you submit specimens to a reference or academic diagnostic laboratory, it is important Equipment & Supplies to ask about procedures and tests that they use. The issue of equipment and supplies should not be Some laboratories are running commercially of much concern. A quality microscope, centrifuge, available tests that you can purchase and your and ancillary supplies are readily available. I often staff can perform. It is prudent to assure that the

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laboratories to which you submit samples are exceptions, seen in pets allowed outdoor access to performing accurate tests. Commercially available the insects, gastropods, and furry creatures that tests should have performance information they might prey upon. Parasites tend to occur (and included in the package inserts. If laboratories reoccur) in certain geographic regions because perform a custom test that they have developed, of climate, prevalence of intermediate hosts, and ask for performance data. vectors.

Cost & Turnaround Time Antiparasitic Drugs & Other Pets Cost and turnaround time both can be less if you Prior use of antiparasitic drugs can confi rm or rule perform diagnostics in-house. Remember, you out a tentative diagnosis based on: always have the option of performing some tests • Which antiparasitic drugs were used yourself and sending others to outside laboratories. • Whether the proper dose was administered I have included several sources of information in • When they were last used. the references section.1-4 Parasites can also be a greater problem when multiple pets are confi ned to smaller areas. 2. What is this parasite? Obviously, the risk of direct transmission is This one almost always begins with, “Doc, I am enhanced, particularly when the pets are of seeing this parasite that I haven’t seen before—can different ages and sexes, as mentioned. you help?” Often it is a telephone description but, occasionally, it is a picture captured by a digital Pseudoparasites camera mounted to a microscope and connected to Keep in mind that other organisms or objects a computer (more about this later). seen in feces and vomitus often are similar in Although it is unlikely to encounter a parasite appearance to parasites. These pseudoparasites can that is not included in the excellent laboratory be challenging. Examples include: manuals available today,1-4 you can shorten your • Tree pollen, which imitates Toxocara eggs search and save time by asking several important • Yeast, which masquerades as Giardia questions: • Free-living worms, which impersonate their • What is the signalment (breed, age, sex, parasitic counterparts reproductive status) and history of this pet? • Large motile bacteria, which resemble motile • Has the pet resided in your practice area its parasites. entire life or did the client move here recently? Yes, diagnosis of parasites can be challenging, • Do they travel with the pet and where? but armed with a little information and experience, • What do you know about recent use of you would be surprised how easily the puzzle is antiparasitic drugs, including what, when, how solved. much, and how often? • What is the pet’s home environment—is it indoors, outdoors, or both? • Does the client oversee a kennel or cattery, or is the pet a member of a multi-pet household? • If the last question’s answer is “yes” to either or both, the age, breed, and sex of other pets can be important.

Signalment & Geographic Region Why all the questions? Parasites are often predictable and tend to have stereotypic behaviors. Certain parasites, such as Toxocara, Ancylostoma, coccidia, and Giardia, are more common in younger pets. Others emerge or re-emerge as FIGURE. Attachment of a digital camera and potential problems during pregnancy and lactation computer with an Internet connection to your microscope will facilitate submission of (sex, reproductive status). Those parasites captured images to experts for diagnosis. that require intermediate hosts are, with some

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Parasite Identi cation and individual pet situations. Veterinarians should I strongly encourage veterinarians to consider carefully review the results of studies that support the use of a digital camera attached to their performance and safety claims. microscopes (Figure, page 87), which allows you to capture images in fecal preparations, blood Learning More smears, skin scrapings, and cytologic preparations Product sponsors are enthusiastic about sharing and email them to your preferred expert. Often their data in the clinic (breakfast meetings, lunch you will have a diagnosis or confi rmation in a very and learn forums) or at regional, local, and short time. national scientifi c meetings. There is no lack of All the equipment required is readily available opportunity for those considering the use of a new through Internet sources. Contact an expert near product to get excellent detailed information. you for more information. As mentioned earlier, Many veterinarians prefer to discuss new several textbooks and/or diagnostic manuals are products with an academic mentor or other trusted 1-4 available to assist veterinarians. professional. Just remember that it is not the responsibility of these individuals to make choices 3. With all of the new antiparasitic drugs for the practice community, but rather to help sort entering the market, I am having a dif cult through the complexities of the data and wealth time deciding which ones to use. What of information that accompany new product products are best? launches. Some veterinarians view the wide variety of available antiparasitic drugs as a liability and burden 4. I have con icting canine heartworm results: in making choices. I view the assortment of new one antigen test is positive, while the follow- products as a bonus. It allows us to individualize up con rmation test is negative. Which test do treatment and prevention for each pet. I believe? This is a common question that can cause Product Criteria signifi cant concern for the veterinarian who must Not surprisingly, criteria used in product selection make a treatment decision. should include: First, let’s deal with the possible reasons for the • Target pet (eg, dog versus cat) discrepancy. If the 2 tests are different platforms • Formulation (oral, topical, injectable) (ie, enzyme-linked immunosorbent assay versus • Efficacy immunomigration) or even similar platforms but • Safety from different manufacturers, they can vary in their • Convenience. Additional criteria could include spectrum performance characteristics. of activity (parasites eliminated), overlap with • Do they possess different sensitivity and products currently used, and existence of parasite specificity properties? resistance. Certainly, veterinarians cannot • Is one easier to read than the other? ignore cost, invoicing and inventory issues, and • Is one more complex than the other with greater prescription (including online pharmacies) versus potential for error? marketing outside the veterinary channel. • Were the tests performed on the same blood sample or on samples collected at different time New Drugs points? New antiparasitic drugs, whether approved by • If one (or both samples) was shipped to another the Federal Food and Drug Administration or laboratory, was the sample stored properly prior Environmental Protection Agency, must comply to shipment and received by the test laboratory with established performance mandates to gain in a short time and in acceptable condition? approval. These products will prevent or eliminate Answers to these questions can help explain the parasites that are included on their labels. why the discrepancy exists and which test result That said, there may be nuances of difference should determine a follow-up strategy. A low between categories of performance, such as speed female heartworm burden that results in circulating of elimination of parasites, residual activity, and antigen levels that are near the minimum detection resistance of topical products to frequent water level of the test is more likely to cause the immersion and bathing, depending on products discrepant result described.

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It is always prudent to interpret a confounding is crucial in implementing a successful parasite heartworm test result together with other available control strategy. One of my favorite quotes is information, such as client compliance and by CR Reinemeyer and MK Nielsen7: They potential resistance to preventives. These issues say, “a thorough knowledge of life cycles is not have been addressed in previous publications.5,6 emphasized merely to torment veterinary students. Also, the clinical condition of the patient, as Rather, life cycle details reveal opportunities to determined by a thorough physical examination control parasites through chemical or management and blood and urine analyses, should always be interventions.” used in conjunction with heartworm test results to The worldwide web provides access to global make sensible treatment decisions. information on virtually any parasite in any location. The sheer number of websites is mind- 5. I am interested in textbooks, laboratory boggling. Examples that should be of interest are manuals, and online information. What are listed in the Table. some available resources? We veterinary parasitologists do not expect This is the easiest of the questions to answer. The veterinarians to be experts on every parasite, but information age is upon us. An extraordinary array use of available information and resources can get of educational resources is available to practicing you closer. veterinarians. Excellent parasitology textbooks and laboratory References manuals are available in either hard copy or 1. Zajac AM, Conboy GA. Veterinary Clinical Parasitology, 8th ed. electronic versions.1-4 Most include high quality West Sussex, UK: Wiley Blackwell Publishing, 2012. 2. Bowman DD. Diagnostic parasitology. In Bowman DD illustrations and photographs that can assist (ed): Georgis’ Parasitology for Veterinarians, 10th ed. St. Louis: veterinarians with the most challenging cases. Saunders Elsevier, 2014, pp 326-398. Many contain detailed life cycles and up-to-date 3. Foreyt WJ. Veterinary Parasitology Reference Manual, 5th ed. Ames, IA: Wiley Blackwell, Ames, 2002. treatment information on companion animals, 4. Blagburn BL. Internal Parasites of Dogs and Cats: Diagnostic livestock, and exotics; understanding life cycles Manual. Greensboro, NC: Novartis Animal Health (now

TABLE. Websites Containing Information & Resources on Parasites RESOURCE WEB ADDRESS CONTENT American Association aavp.org Website maintained by expert veterinary parasitologists of Veterinary worldwide; source of late-breaking research via the Parasitologists (AAVP) proceedings of the AAVP annual meetings. American Heartworm heartwormsociety.org Excellent resource on all aspects of heartworm; monitored Society and maintained by knowledgeable experts. Centers for Disease cdc.gov/parasites/ Excellent resource for human parasitic diseases and Control information on parasites that infect both humans and animals; monitored and maintained by knowledgeable experts. Companion Animal capcvet.org All things parasitic for companion animals; monitored and Parasite Council maintained by knowledgeable experts. Excellent site for (CAPC) parasite prevalence maps and forecasts. Maintains up-to-date summary sheets on important parasites of companion animals. Companion Animal petsandparasites.org An excellent consumer-oriented companion website to Parasite Council CAPC. Forecast maps for selected parasitic and vector-borne (Consumer Website) diseases are also available here for clients. Information is less technical and more easily understood by clients. National Center ncvetp.org National interinstitutional veterinary parasitology training for Veterinary center; excellent training program for future veterinary Parasitology parasitologists. Numerous resources for teaching and diagnostic veterinary parasitology. University of Rhode tickencounter.org Excellent information on ticks with an emphasis on prevention Island Tick Resource of tick infestations and tick-borne diseases in humans. Center Note: Several of these websites contain links to other resources.

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Elanco Animal Health, Greenfi eld, IN), 2004. 5. Atkins CE, Murray MJ, Olavessen LJ, et al. Heartworm ‘lack of effectiveness’ claims in the Mississippi delta: Computerized analysis of owner compliance–2004-2011. Vet Parasitol 2014; 206:106-113. 6. Bowman D. Heartworms, macrocyclic lactones, and the specter of resistance to prevention in the United States. Parasites Vectors 2012; 5:138. 7. Reinemeyer CR, Nielsen MK. Handbook of Equine Parasite Control, 1st ed. Ames, IA: John Wiley & Sons, 2013, p 3.

BYRON L. BLAGBURN Byron L. Blagburn, MS, PhD, Diplo- mate ACVM (Hon), is a Distinguished University Professor at the Auburn University College of Veterinary Medicine. He is past president of the Companion Animal Parasite Council. He has served as an associate editor for the Journal of Parasitology and on the editorial boards of veterinary, research, and microbiology journals. He is a recipient of the American Association of Veterinary Parasitolo- gists’ Distinguished Veterinary Para- sitologist Award and the Pfi zer Award for Research Excellence. He received his doctorate in parasitology from University of Illinois.

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