Poliomyelitis in relation to intramuscular injections of quinine and other drugs

Intramuscular injections within 30 days of immunization with oral poliovirus vaccine--a risk factor for vaccine-associated paralytic poliomyelitis

BACKGROUND

In Romania the rate of vaccine-associated paralytic poliomyelitis is for unexplained reasons 5 to 17 times higher than in other countries. Long ago it was noted that intramuscular injections administered during the incubation period of wild-type poliovirus infection increased the risk of paralytic disease (a phenomenon known as "provocation" poliomyelitis). We conducted a case-control study to explore the association between intramuscular injections and vaccine-associated poliomyelitis in Romania.

METHODS

The patients were 31 young children in whom vaccine-associated paralytic poliomyelitis developed from 1988 through 1992. Eighteen were vaccine recipients, and 13 had acquired the disease by contact with vaccine recipients. Each of these children was matched with up to five controls according to health center, age, and in the case of vaccine recipients, history of receipt of the live attenuated oral poliovirus vaccine. Data were abstracted from medical records that documented the injections administered in the 30 days before the onset of paralysis.

RESULTS

Of the 31 children with vaccine-associated disease, 27 (87 percent) had received one or more intramuscular injections within 30 days before the onset of paralysis, as compared with 77 of the 151 controls (51 percent) (matched odds ratio, 31.2; 95 percent confidence interval, 4.0 to 244.2). Nearly all the intramuscular injections were of antibiotics, and the association was strongest for the patients who received 10 or more injections (matched odds ratio for > or = 10 injections as compared with no injections, 182.1; 95 percent confidence interval, 15.2 to 2186.4). The risk of paralytic disease was strongly associated with injections given after the oral polio virus vaccine, but not with injections given before or at the same time as the vaccine (matched odds ratio, 56.7; 95 percent confidence interval, 8.9 to infinity). The attributable risk in the population for intramuscular injections given in the 30 days before the onset of paralysis was 86 percent (95 percent confidence interval, 66 to 95 percent); that is, we estimate that 86 percent of the cases of vaccine-associated paralytic poliomyelitis in this population might have been prevented by the elimination of intramuscular injections within 30 days after exposure to oral poliovirus vaccine.

CONCLUSIONS

Provocation paralysis, previously described only for wild-type poliovirus infection, may rarely occur in a child who receives multiple intramuscular injections shortly after exposure to oral poliovirus vaccine, either as a vaccine recipient or through contact with a recent recipient. This phenomenon may explain the high rate of vaccine-associated paralytic poliomyelitis in Romania, where the use of intramuscular injections of antibiotics in infants with febrile illness is common.

Provocation poliomyelitis and entry of poliovirus to the CNS

It is proposed that entry to the CNS by poliovirus occurs from multiple sites which are seeded during viremia. At each site, an inflammatory reaction allows entry to peripheral nerves. Differences in incubation times are related to the length of nerve to be followed. Virus reaches the CNS sequentially but does not in natural poliomyelitis spread within the CNS. Provoking agents are identified as immunogenic and their action explained. Details of paralysis among Cutter vaccinees are explained by this model, as well as the effects of multiple inoculation in monkeys. Clinical symptoms in the preparalytic stage of poliomyelitis are consistent with this model.

The effect of vaccines and other substances upon the course of neurotropic virus infection

1. When GDVII virus was injected into the brains of mice, subsequent intracerebral injections of mixed pertussis and diphtheria prophylactic significantly shortened the incubation period. Subsequent intramuscular injections of mixed prophylactic had no influence on the course of the infection.

2. Intramuscular inoculation of either GDVII virus or EMC virus results in a marked localization of paralysis in the injected limb. With GDVII virus, the localization probably arises from the use of the sciatic nerve route for entry into the c.n.s., and is unaffected by injection of substances into the opposite limb. With EMC virus, localization can be modified by injections into the opposite limb.

3. When GDVII or EMC virus was injected by a peripheral route other than intramuscular, intramuscular injections of vaccines or normal mouse brain suspension induced localization of paralysis in the injected limb.

4. Intramuscular inoculation of vaccines increased mortality in mice injected into the same limb muscle with GDVII virus. Within the limits tested the later the vaccines were injected relative to the virus, the greater was the effect.

5. When the vaccines used were more than a few months old, this facilitating effect was replaced by a protective effect. Mice injected intramuscularly with aged vaccines were significantly more resistant than the controls to GDVII virus injected into the same muscle.

6. Intracerebral inoculation of vaccines, and to a lesser extent other substances, increased mortality in mice which had received intramuscular inoculations of GDVII virus, by allowing virus to pass directly from the blood into the brain. This resulted in a predominance of cerebral symptoms when the vaccines were injected immediately after the virus, but not when the interval was lengthened to 48 hr.

7. The mode of action of modifying factors in neurotropic virus infections is discussed in the light of these results.

This work was done in the Department of Zoology, Oxford University, during the tenure of a grant from the Medical Research Council. I also wish to thank the Nuffield Foundation for their support of the virus research carried on in the Department.

I am most grateful to Dr F. K. Sanders for his advice and criticism, as well as for provision of technical facilities, and to Dr Donald Michie for assistance with the statistical treatment of the data, and for much other help.