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Year : 1964  |  Volume : 12  |  Issue : 2  |  Page : 59-64

Results of antitrachoma vaccination trials in East Africa

1 Eye Clinic, University of Rome, Italy
2 Haile Sellassie 1st Ophthalmic Centre, Ethiopia
3 Institute Superiore di Sanita, Dept of Microbiology, Rome, Italy

Date of Web Publication14-Feb-2008

Correspondence Address:
G B Bietti
Eye Clinic, University of Rome
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Source of Support: None, Conflict of Interest: None

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How to cite this article:
Bietti G B, Guerra P, Felici A, Vozza R. Results of antitrachoma vaccination trials in East Africa. Indian J Ophthalmol 1964;12:59-64

How to cite this URL:
Bietti G B, Guerra P, Felici A, Vozza R. Results of antitrachoma vaccination trials in East Africa. Indian J Ophthalmol [serial online] 1964 [cited 2023 Dec 10];12:59-64. Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?1964/12/2/59/39076

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Table 2

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Table 2

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Table 1

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Table 1

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The experiments on the prevention and therapy of the trachomatous infec­tion were started by our group in Ethiopia in 1960.

Preliminary results of these trials were already reported (1961), (1962), (1963) but only now, after 4 years, it is possible to attempt a better evalua­tion of the collected data.

  Materials and Methods Top

All the vaccines used in these ex­periments were inactivated with 0,02% formaline and prepared from the strain trachoma Asmara 3 / 1960.

Contents of the Vaccines and Schedule of Vaccination

(a) Aqueous vaccine : Suspension of purified elementary bodies in saline to make up a final 100% YSP (Yolk Sac Pool).

Administration : First intramuscular injection 1 ml.; booster after 30 days with 1 ml. of 50%, YSP.

(b) Vaccine adsorbed on Aluminium hydroxide: Suspension of equal parts of purified and concentrated element­ary bodies in saline and of aluminium (18 mg/ml) to make up a final con­centration of 200% YSP. Before ad­ministration, suspension was shaken and kept over-night at + 4°C.

Administration : First intramuscular injection 0.5 ml; booster after 40 days with 1 ml of aqueous vaccine 50% YSP.

(c) Water-in-oil emulsion vaccine: Suspension of equal parts of purified and concentrated elementary bodies in saline and oil adjuvants (Arlacel A, I part, Bayol F, 9 parts) to make up a final concentration of 200% YSP. Suspension was stirred in a Waring blendor until a stable milky emulsion was obtained.

Administration: First intramuscular injection 0.5ml; booster after 40 days with 1 ml of aqueous vaccine 50 YSP. A second booster was also tested after 6 months using 0.5 ml of water-in-oil emulsion vaccine. Each of the vaccine in every experiment was prepared from a single YSP of the strain Asmara/ 3 / 1960, so that the concentrations of elementary bodies of similar amounts of viral suspensions were considered equivalent.

  Safety Tests Top

Fifteen guinea pigs, for each type of vaccine were inoculated by the intra­peritoneal route with 1 ml without evidence of harmful side effects. Deep intramuscular injection of 0.5 ml of water-in-oil and aluminium vaccine did not produce local and general alter­ations in five monkeys. Similar doses were found without side effects in men. A fourfold concentrated dose of water­in oil vaccine administered to one of us (A.F.) did not produce local or general alterations.

  Evaluations of the Results and Clinical Checks Top

For a careful evaluation of the re­sults, both vaccinated and control in­dividuals were grouped following McCallan's classification. Within Trachoma II and III groups, light cases (f+) were evaluated separately from the more severe ones (f++, f+++).

Individuals considered as healthy were generally under 1 year of age and seldom exceeding 2 years. Only in this group we believe to exist consistent possibilities that the individuals had not been affected by the disease in an highly endemic area. Clinical checks were performed every 2 months for 1960 experiments. In the following, the first check was carried out after 6 months and then successively every year. The clinical evaluation was car­ried out with the following criteria :

a) Analytic evaluation

Clinical cure: disappearance of fol­licles

Improvement: shift from the category "severe trachoma" (f++, f+++) to "mild trachoma" (f+)

Worsening: opposite of improvement

No change: permanence in the initial category

Relapse or reinfection : appearance of follicles in an individual affected by non active (non follicular) trachoma

Infection: appearance of follicles in healthy individuals.

b) Synthetic evaluation

This evaluation considers a positive and a negative clinical course. Positive means cure or improvement in active cases, no change in trachoma dubium (D) healthy or Tr IV case) whereas a negative course means no change or worsening in active cases, relapses and/or reinfections in non active cases, in­fection of healthy cases, clear disease i n Tr D.

  Selection of Cases Top

Vaccinated and control individuals were selected, when possible, in the same environment (schools, orphan­ages, villages and other communities) comparing cases of the same age af­fected by disease of comparable seve­rity.

By this way the following groups were treated: [Table - 3]

  Environment of Vaccination Trials Top

Year 1960-Vaccination trials were carried out in three villages at about 30 Km. from Asmara and in Keren's orphanage, about 90 Km. from it.

Both active and non active case were vaccinated. The age of vaccinat­ed individuals ranged between two and fifteen years.

Year 1961-Vaccination trials and controls were performed in primary schools in Asmara and in the neigh­bouring villages. Active and non ac­tive cases were vaccinated. The age ranged between two and fifteen years.

Year 1962-Vaccination trials and controls were performed on children of the Police Constables of Asmara and neighbouring stations.

Only individuals affected by active, non-cicatricial trachoma and healthy individuals under two years of age were vaccinated. The age was generally near to or less than four years.

  Results Top

Results were read by an ophthalmo­logist, ignorant of the treatment car­ried out. Within the limits of practi­cal possibilities the same ophthalmo­logist performed the first and the fol­lowing readings of every experiment.

1) Innocuity

The antitrachoma vaccines used proved to be free of harmful side­-effects. Only in newborns within the first year of age, the injection of water-­in-oil-emulsion vaccine gave place to a small nodule which was palpable at the time of the booster.

2) Activity

The results collected in the clinical checks are summarized in [Table - 1],[Table - 2]

[Table - 1] reports the results in rela­tion to the type of vaccination while [Table - 2] is prepared with the informa­tion collected in 6 following clinical checks performed during 36 months on the subjects vaccinated with water-in­-oil emulsion vaccine, which is the more widely used so far, in our trials.

As evident from the two tables, the number of vaccinated cases under­went considerable reduction during the checks, owing to the lack of coopera­tion and to the very marked nomadism of the Erythrean populations in the vaccinated districts. This factor ac­counts for the reduced size of certain figures which are reported although de­prived of statistical significance.

The data reported in [Table - 1] de­monstrate that vaccination without booster is scarcely effective in preven­tion and therapy both using aqueous and oil vaccination, although a better response was obtained with the latter. The best results were recorded with oil vaccination followed by one or two boosters, after 45 days and 6 months respectively.

Although the figures were consider­ably cut down by the aforementioned factors, the vaccination with A1(OH) 3 adsorbed vaccines seems to give slightly inferior results. This type of vaccination was however considered with particular attention owing to the ban of some pharmacopeias towards oil adjuvants.

The following conclusions can be drawn from an analysis of the data collected in [Table - 2]

1) The efficacy of the vaccination with oil adjuvants is conditioned by a booster shot. Simple vaccination has only a limited preventive and therapeu­tic activity. A second booster per­formed after six months with water-­in-oil vaccine greatly improved the re­sults as it is shown in [Table - 1].

2) Vaccination reduces the rate of morbidity of apparently healthy sub­jects for at least one year.

3) Vaccination reduces considerably for 2 years the number of cases of "trachoma dubium" (TrD) which de­velop a clear cut disease.

4) The relapses and/or reinfections of cicatricial cases (TrIV) are prevent­ed considerably for about 2 years.

This point is worthy of attention in view of the possibility of using vacci­nation after the cure obtained by means of common therapeutic agents.

5) Active trachoma both in its It and III stage regardless of its severity, is favourably influenced by vaccination which gives place to a good incidence of favourable courses. The persistence of some cases with a very scanty num­ber of follicles (f+) shows that the disease was controlled to a degree of severity, scarcely dangerous to impair vision.

The favourable effects of the vacci­nation are still detectable after 36 months, although the reduction of the size of the experiment does not allow definite conclusions on this point.

  Discussion Top

Our experience with inactivated, monotypic trachoma vaccines in East Africa has to be considered favour­able even if its efficacy is far from be­ing absolute in its preventive and thera­peutic aspects.

Many important problems are still unsolved despite the considerable in­formation already collected in this field.

Substantial improvements could be achieved by the use of polyvalent types of vaccines, provided that the existence of strain antigenic differences will be ascertained. At the present time no un­disputable information is available on this point.

Other improvements could result from the use of more concentrated suspensions of elementary bodies in different media. A trial on 10.000 cases is in advanced stage of deve­lopment in Ethiopia using an AL(OH) 3 , adsorbed monotypic vaccine, concen­trated fourfold in relation to the pre­sent ones.

Particular attention should also be given to the use of vaccines in associa­tion with minimal chemotherapeutic treatment. Preliminary trials the results are reported elsewhere (1963) gave particularly encouraging data.

Concluding, the experience collected so far allows us to foresee that anti­trachoma vaccines will probably find their place in the near future among the valuable agents for the mass con­trol of the disease.

Even if the results of the vaccination will turn out to be slightly inferior to those of chemoantibiotic treatment, the advantages of an easier adminis­tration and of the more lasting pro­tection has to be taken into considera­tion. This is particularly true in under­developed countries where other pro­longed general and local treatments are sometimes difficult or impossible.[3]

  Acknowledgement Top

This research was carried out with funds from the imperial Ethiopian Government, to which the authors are greatly indebted.

  References Top

FELICI, A.; VOZZA, R. (1961) R. C. 1st. Sup. Sanita, Roma: 23, 1242.  Back to cited text no. 1
BIETTI, G. B.; GUERRA, P.; FELICI, A.: VOZZA, R. (1963) Arch. Soc. Ophthal. Jan.: 66, 362.  Back to cited text no. 2
BIETTI, G. B.; GUERRA, P.; FELICJ, A.; VOZZA, R. (1963) Orient. Arch. Ophthal.: 72, 92.  Back to cited text no. 3


  [Table - 1], [Table - 2], [Table - 3]


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