VACCINE-PREVENTABLE DISEASES

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The Centers for Disease Control and Prevention established national goals for elimination of measles, rubella, polio, tetanus in persons under 15 years of age, and elimination of diphtheria, and Haemophilus influenzae type b disease in children under 5 years of age by 1996. These goals (zero cases), adopted by Indiana, were met for all targeted diseases except for diphtheria. No specific goals were established for mumps and pertussis.

Rubella Cases = 0

Measles Cases = 0

For the second consecutive year there were no cases of measles; for the third year there were no cases of rubella confirmed in Indiana. As we approach the goal of eliminating indigenous measles in the United States, it is important to ensure that cases that do occur are identified in a timely manner by the surveillance system. Indicators of the sensitivity of the measles surveillance system have been established. One of these indicators is the number of cases meeting the clinical case definition in which measles is ruled out by serologic testing.

Of the three suspects that met the clinical case definition for measles, two were ruled out by serologic testing. (The third suspected case was not tested.) Another twelve suspected cases were reported to ISDH as measles, but did not meet the clinical case definition for measles; 9 (75%) of them were also ruled out by serologic testing. It is necessary to obtain sera (3-4 days after rash onset) on all cases meeting clinical criteria. This enhances the sensitivity and specificity of measles surveillance programs. None of these 15 suspected cases were reported to CDC as measles.

Polio Cases = 0

Tetanus Cases = 0

There were no cases of polio (vaccine-associated or wild type virus) or tetanus in 1996.

Cases = 0

Twenty-one cases reports of invasive H. influenzae serotype b (Hib) disease were submitted to ISDH in 1996, five were in children under five years of age. Of these five suspected cases, only two were serotyped; neither were laboratory-confirmed as type b. Nine isolates from all age groups were serotyped, none of which were type b. A stated goal of the immunization program is to improve the proportion of suspected Hib invasive disease for which serotypes are obtained. Serotyping of isolates is necessary to determine if Hib disease is being reduced in the population.

Cases = 1

A case of respiratory diphtheria due to Corynebacterium ulcerans was diagnosed in a 54 year old female in October. This was the first case of diphtheria in Indiana since 1970. Although Corynebacterium diphtheriae is the usual causative organism of respiratory diphtheria, C. ulcerans has been shown to cause symptoms indistinguishable from those of C. diphtheriae. C. ulcerans has been associated with zoonotic transmission, most commonly associated with consumption of unpasteurized milk. It is not thought to be spread person-to-person. Although the likelihood of diphtheria caused by either organism is remote at this time, low adult vaccination levels and the threat of importation from endemic countries, such as the states of the former Soviet Union, remain a concern. Vaccination prevents disease from either organism.

Cases = 128

In contrast to the low incidence of other vaccine-preventable diseases, there were 128 cases of pertussis reported in Indiana in 1996. This is the third time since 1986 that more than 100 cases have been reported in any year. This follows a national trend which shows pertussis on a gradual increase, particularly in older age groups. Over 7,000 cases were reported in the U. S. in 1996, the highest level since 1966, when over 7,700 cases were reported. In Indiana, 78 cases (61%) were in children under five years of age. Twenty percent of cases occurring in 1996 were in those 18 years old and older. The greatest increase in incidence during the last two years is among the adult population (Pertussis-1).

Late summer and early fall continue to be the peak time for onset as 47% of the cases had cough onset during the three months of August - October (Pertussis-2).

Over 52% of the cases occurred in 5 counties (Marion 24%, Lake 9%, Ripley 7%, Elkhart 6%, and Dearborn 6%). Increased awareness that adults are at risk of pertussis may lead to better case- finding and an increase in reported cases. On-schedule immunization of infants, prompt testing and reporting of cases, case investigation, and antibiotic prophylaxis of contacts are the primary means of pertussis control.

Cases = 8

Mumps incidence remains at a low level in the state, with only eight cases being confirmed in 1996. Since 1991, no more than 12 cases have been reported in any year. Four of the eight cases in 1996 were confirmed by serologic testing. Five cases were under 15 years of age; five had received at least one mumps vaccination. Serologic testing in indicated in confirming the causative agent in cases presenting as a febrile rash illness. In 1996, 29 suspected cases of mumps were ruled out -- serologic tests were obtained and found to be negative on 22 (76%) of these cases. Of those cases ruled out, 23 had history of at least one dose of mumps vaccine. A goal of less than 10 confirmed cases has been set for 1997.

The continuing low or falling levels of vaccine-preventable disease cases in Indiana demonstrates the effectiveness of vaccination of appropriate populations as a preventive strategy. To continue at zero level for the five diseases and to reduce the levels of other vaccine-preventable diseases continued emphasis must be placed on reaching the goal of having 90% of two year olds complete the primary vaccination series by their second birthday. A surveillance system that will ensure the identification, control, and elimination of vaccine-preventable diseases must include prompt case reporting, rapid confirmation of cases, expanded case finding and timely implementation of control measures.

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