Vaccine-preventable diseases: Uncommon disease primer for the front-line provider

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Immunization programs have been pivotal in decreasing the rates of specific diseases over the past few decades, in Canada and around the world ^[1]. Vaccine program successes have ensured that most practicing physicians in Canada have never seen a case of vaccine-preventable disease (VPD) such as polio, measles, congenital rubella syndrome, diphtheria, tetanus or mumps. This ‘primer’ is intended to alert and inform front-line practitioners regarding when to include such diseases in their differential diagnoses.

Common themes

Asking questions around potential exposure history (e.g., travel to an endemic area) with every family can elicit important clues to disease risk. Other ‘red flags’ include:

• delayed, incomplete or no immunizations in a Canadian-born child or youth.
• immigrant or refugee children or youth, who may be immunized incompletely or not at all. They may also have received improperly stored vaccines and/or been too malnourished to respond optimally.

Consultation with an expert in infectious diseases or public health is recommended to determine whether testing and isolation precautions are indicated. All VPDs described here must be reported to local public health authorities because they are nationally notifiable ^[2].

Disease-specific issues

Polio: Most cases of polio are asymptomatic or present as a short, self-limiting illness. A small proportion of cases (approximately 1%) result in paralysis. Paralytic poliomyelitis is characterized by an acute onset of asymmetric flaccid paralysis, possibly preceded by pain in the affected limb. This symptom is often preceded by sore throat, fever and sometimes (less commonly) by a stiff neck (for details, see http://www.phac-aspc.gc.ca/im/vpd-mev/poliomyelitis/professionals-professionnels-eng.php). As of June 2018, only two countries (Afghanistan and Pakistan) have reported endemic transmission of poliovirus ^[3], but some countries continue to use oral polio vaccine (OPV) without prior inactivated polio vaccine (IPV). OPV is a rare cause of polio due to a circulating vaccine-derived poliovirus (CVDP); it can occur in recipients and their contacts as fecal-oral infection spreads from poliovirus shed in the stool. The World Health Organization (WHO) has recommended that all children receive at least one dose of inactivated polio vaccine (IPV) to further limit risk for infection by CVDP ^[4].

For any patient presenting with acute flaccid paralysis or suspected Guillain-Barré syndrome, it is important to determine whether that individual or any close contacts have travelled and whether they have been exposed to OPV. Even when there is no such history, stool should be submitted for poliovirus testing. A link to a standardized Molecular Detection and Characterization Form is found here: https://www.cnphi-rcrsp.ca/gts/faces/public/rdt.xhtml?lang=en&rdtId=10039&labId=1012. Stool collection and sample shipping can be facilitated by public health or the laboratory at the nearest children’s hospital. A single case of polio is a ‘public health emergency of international concern’ (PHEIC) and therefore must be reported to public health authorities as soon as possible ^[5].

Measles: This disease continues to be imported to Canada on a fairly regular basis, typically through international travel by individuals who are not fully immunized ^[6]. Measles is characterized by cough, coryza and conjunctivitis, followed after a few days by a descending maculopapular rash. Individuals with measles often have Koplik’s spots in their mouths—bluish-white spots on a background of red on the buccal mucosa. Complications from measles, including otitis media, pneumonia, encephalitis or death, still occur. For details, see http://www.healthycanadians.gc.ca/diseases-conditions-maladies-affections/disease-maladie/measles-rougeole/index-eng.php.

Congenital rubella syndrome (CRS): Some low- and middle-income countries do not vaccinate against rubella ^[7]. One high-risk situation for CRS in Canada is when a pregnant, unimmunized woman travels to visit friends or relatives in a region where rubella remains endemic. She could experience a mild viral illness that may go unnoticed, but a fetus exposed to the virus before 20 weeks gestational age can die or develop permanent manifestations, such as congenital heart disease, cataracts and/or hearing impairment. For details, see http://www.healthycanadians.gc.ca/diseases-conditions-maladies-affections/disease-maladie/rubella-rubeole/professionals-professionnels-eng.php. CRS must be excluded in all cases of unexplained congenital cataracts. Later manifestations of CRS can include developmental delay. Provided they are not pregnant, immigrant and refugee women of childbearing age should receive a dose of MMR vaccine as soon as possible after arriving in Canada, unless there is positive proof that they are immune to rubella ^[8]. Testing this population for immunity before administering MMR vaccine is not recommended. 

Diphtheria: This disease typically presents with sore throat, weakness, fever and a rapidly progressive swelling of the neck. For details, see http://www.phac-aspc.gc.ca/im/vpd-mev/diphtheria-diphterie/professionals-professionnels-eng.php. Within a few days, a thick ‘pseudo-membrane’ builds up in the throat or nose that can lead to severe respiratory compromise. Bleeding ensues if the membrane is lifted. Diphtheria toxin can also become disseminated systemically and cause damage to the kidneys, central nervous system and heart. Infection can be fatal even with early treatment, underlining the essential role of preventive immunization.

Tetanus: This VPD is of particular concern in under-immunized children in Canada because infection is unrelated to travel and herd immunity plays no role in protection. Classic exposure occurs through a cut or from puncture wounds contaminated by dirt or excreta, but sometimes there is no history of injury. Acute symptoms include muscle rigidity and spasms, similar to rabies. For details, see http://www.phac-aspc.gc.ca/im/vpd-mev/tetanus-tetanos/professionals-professionnels-eng.php. Infection can be fatal even with intensive care, underlining the essential role of preventive immunization.

Mumps: Clinical presentation often includes non-specific prodromal symptoms, such as headache, myalgias and a low-grade fever. For details, see http://www.phac-aspc.gc.ca/im/vpd-mev/mumps-oreillons/professionals-professionnels-eng.php. The classic presentation is unilateral or bilateral parotitis. Complications are rare and include orchiditis, mastitis, oophoritis, pancreatitis, meningitis and encephalitis. Unlike the other VPDs described here, vaccine failure is common with mumps. Therefore, testing should be considered in all cases of parotitis unless the infection is confirmed to be bacterial in origin.

With continuing immunization efforts nationally and internationally, polio may soon be eradicated. Program targets are set for the eradication of measles and congenital rubella and may also be possible for diphtheria and mumps. Because the tetanus toxin is made by bacterial spores that persist naturally in the environment, tetanus will always require ongoing immunization to prevent disease.

Key practice points for symptom recognition and infection control of uncommon VPDs include:

1. Ongoing vigilance, especially in individuals who are not fully immunized or have recently travelled to an endemic area or are newly arrived in Canada.
2. Awareness of measles or mumps cases in the community and outbreaks elsewhere that may spread. Public health provides current information through local websites and bulletins.
3. Involving public health authorities and/or an infectious diseases specialist early. Most VPD cases require a public health intervention. It is better to over-suspect than under-suspect these diagnoses.

Recommended resource:

Moore DL, ed. Your Child’s Best Shot: A Parent’s Guide to Vaccination, 4th edition. Ottawa, Ont.: Canadian Paediatric Society, 2015.

Acknowledgements

This practice point has been reviewed by the Community Paediatrics Committee of the Canadian Paediatric Society.

CANADIAN PAEDIATRIC SOCIETY INFECTIOUS DISEASES AND IMMUNIZATION COMMITTEE

Members: Michelle Barton-Forbes MD; Natalie A. Bridger MD; Shalini Desai MD; Michael Forrester MD; Ruth Grimes MD (Board Representative); Charles Hui MD (past member); Nicole Le Saux MD (Chair); Marina I Salvadori MD (past member); Otto G. Vanderkooi MD
Liaisons: Upton D. Allen MBBS, Canadian Pediatric AIDS Research Group; Tobey Audcent MD, Committee to Advise on Tropical Medicine and Travel (CATMAT), Public Health Agency of Canada; Carrie Byington MD, Committee on Infectious Diseases, American Academy of Pediatrics; Fahamia Koudra MD, College of Family Physicians of Canada; Rhonda Kropp BScN MPH, Public Health Agency of Canada; Marc Lebel MD, IMPACT (Immunization Monitoring Program, ACTIVE); Jane McDonald MD, Association of Medical Microbiology and Infectious Disease Canada; Dorothy L. Moore MD, National Advisory Committee on Immunization (NACI);
Consultant: Noni E. MacDonald MD
Principal authors: Shalini Desai MD, Noni E. MacDonald MD

References

Disclaimer: The recommendations in this position statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. Internet addresses are current at time of publication.