Viral isolation from cases of epidemic neuropathy in Cuba.

OBJECTIVE: To investigate the possibility of a viral agent in the central nervous system of patients with epidemic neuropathy. DESIGN: Virus isolation attempts, in cell cultures and suckling mice, from cerebrospinal fluid (CSF) of neuropathy patients and controls undergoing lumbar puncture for unrelated reasons. Serologic studies in patients, contacts, and controls. SETTING: An epidemic of optic and peripheral neuropathy affected more than 50,000 people in Cuba in 1991 through 1993. Illness was associated with dietary limitations and increased physical demands accompanying the shortages of food and fuel experienced in Cuba since 1989. Most patients responded to parenteral vitamin therapy, and the epidemic began to subside when oral vitamin supplementation was begun for the entire Cuban population. RESULTS: Coxsackievirus A9 (five isolates) and a similar, less cytopathic virus (100 isolates) were recovered from 105 (84%) of 125 CSF specimens from neuropathy patients. The strains with light cytopathic effect were antigenically related to Coxsackieviruses A9 and B4 by cross-neutralization and immunoblotting assays. Virus persisted in CSF of some patients for 1 to 12 months. Cerebrospinal fluid from patients and both types of virus from cell culture produced illness, including complete posterior flaccid paralysis, in newborn mice, and virus was reisolated from the mice. Mouse tissues and sural nerve biopsy specimens from patients were stained by immunoperoxidase and colloidal gold techniques using hyperimmune rabbit antisera against the virus with light cytopathic effect. CONCLUSIONS: Coxsackievirus A9 or an antigenically related agent with a light cytopathic effect was present in CSF of 84% of 125 patients with epidemic neuropathy. The role of these agents, probably in combination with nutritional factors, in the pathophysiology of the disease requires further investigation.

Lessons from Cuba: mass campaign administration of trivalent oral poliovirus vaccine and seroprevalence of poliovirus neutralizing antibodies.

The immunogenicity of trivalent oral poliovirus vaccine (TOPV), which is less effective in tropical than in temperate areas, may potentially be improved in several ways, including increasing the number of doses. Little information is available on TOPV when more than 6 doses are given. The situation in Cuba provides a unique opportunity to relate the seroprevalence of neutralizing antibodies to the dose of TOPV because Cuba has not reported culture-confirmed poliomyelitis since 1973 and TOPV is only administered in twice yearly 1-week mass immunization campaigns. Sera from 2000 children nationwide were studied for neutralizing antibody among children who received 0, 2, 4, 6 and 8 doses of TOPV. These doses were administered in the period 1989-91, when TOPV (from the USSR) was being used with 500,000, 200,000, and 300,000 median tissue-culture-infecting doses (TCID50) for types 1, 2 and 3, respectively--the 5:2:3 formulation. Seroprevalence of neutralizing antibody after two TOPV doses was 91.5% for type 1, 90.8% for type 2, and 45.9% for type 3. Seroprevalence of type-3 neutralizing antibody after 6 doses remained low (73.4%), but increased to 83.5% after 8 doses (P < 0.05). Although 16.5% of the children remained unprotected for type-3 infection even after 8 doses, mass campaign immunization strategies were sufficient to eradicate the transmission of wild poliovirus in Cuba. Because the seroprevalence of type-1 neutralizing antibody was high (91.5%) after two campaign doses, additional studies using different formulations are needed to determine whether simultaneous improvement in the type-3 response to two campaign doses can be achieved.

PIP: During December 1991-January 1992 in Cuba, health workers took blood samples from a nationwide sample of 2000 children aged 0-3 who received 0, 2, 4, 6, and 8 doses of trivalent oral poliovirus vaccine (TOPV) to determine the seroprevalence of poliovirus neutralizing antibodies for types 1, 2, and 3. Specifically, researchers wanted to learn whether TOPV becomes more effective as the number of doses increases. Since 1973, Cuba has conducted two mass immunization campaigns each year in February and April. During 1970-91, Cuba used a USSR-produced poliovirus vaccine that had 500,000, 200,000, and 300,000 median tissue-culture-infecting doses for types 1, 2, and 3, respectively. Wild poliovirus has not been transmitted in Cuba since 1973 (as of August 1993), indicating that the mass immunization campaigns without routine vaccine delivery have eradicated poliomyelitis in Cuba. The seroprevalence of poliovirus neutralizing antibodies for type 1 increased significantly between 2 and 4 doses (91.5% vs. 96.5%; p = 0.05), thereafter the increases were small and insignificant. The seroprevalence of poliovirus neutralizing antibodies for type 2 increased significantly between 2 and 4 doses (90.8% vs. 97.2%), with small insignificant increases thereafter. Two doses of TOPV induced a response against poliovirus type 3 in only 45.9% of cases. At 4 doses and 8 doses, it did increase significantly from the previous dose (71.2% and 83.5%, respectively; p 0.05). Further studies using other vaccine formulations would allow persons involved in global eradication efforts to determine whether two campaign doses can improve the immunogenicity of the type 3 poliovirus while also improving that of the type 1 poliovirus.

[Development and evaluation of an ELISA for the detection of IgM antibodies against the hepatitis A virus]. / Desarrollo y evaluación de un ELISA para la detección de anticuerpos IgM contra el virus de la hepatitis A.

We present the results of the normalization of an IgM capture ELISA method for the diagnosis of type A viral hepatitis with reagents produced in the laboratory and its comparison with the "Diag-A-Hep" commercial ELISA. The results attained were: sensibility by 91%; specificity by 100%; and coincidence of the two systems by 97%. Results are discussed and their relationship with clinical symptoms and epidemiological characteristics is established. The results attained in 13 serum samples taken from patients seen during 2 acute viral hepatitis outbreaks agreed with clinical findings.