Rabies and its prevention

The increase in world-wide travel means that physicians everywhere require an understanding of rabies and its prevention, to advise intending travellers, or to follow-up on treatment begun overseas. In this article, we discuss measures to prevent rabies.

Dog-bite injuries at a Bangkok teaching hospital

Thailand has a large domestic and stray dog population and Buddhist cultural beliefs encourage feeding and protection of stray animals. Dog bites are common injuries encountered in emergency rooms throughout the country. A prospective study of such bites seen at a teaching hospital in Bangkok revealed that: (1) dog bites represent 5.3% of injuries seen in the emergency room; (2) the majority occur on the street, are inflicated by stray dogs and are interpreted by the victim as unprovoked. Children and teenagers account for 55% of the victims. The lower extremities (54%) and upper extremities (20%) were the most common sites for bites. 9% of patients were bitten on the face or head. In addition to pain, risk of infection (approximately 13%) and the significant cost of caring for these injuries, victims often experienced prolonged anxiety because of to the generally known risk of rabies in Thailand. Due to the high cost of imported immune globulins and vaccines, rabies exposures are not always managed optimally in Asia.

Immune response to rabies vaccine in Alaskan dogs: failure to achieve a consistently protective antibody response

Previous studies in Thailand and Tunisia have shown that one injection of dog pre-exposure rabies vaccine does not produce a lasting antibody titre in a significant group of animals. We therefore duplicated the Thai study in a small North American community using healthy, owned dogs. A tissue culture vaccine of known high antigenicity was given intramuscularly as one primary injection and antibody titres were determined by the rapid fluorescent focus inhibition test on days 14, 30, 60, 180 and 360. Titres were less than 0.5 i.u./mL in 27% of dogs bled at 2 months, 24% at 6 months, and in 33% one year after the primary vaccination. In rabies endemic regions, it may be hazardous to rely on the previous vaccine history of a biting dog when making post-exposure management decisions. A retrospective study of antibody levels in previously vaccinated dogs in North America also indicated that a single injection of vaccine often failed to result in adequate titres.

Immune activation in human rabies

Serum cytokines were compared by enzyme-linked immunosorbent assay among (i) 28 patients with rabies, (ii) 13 patients with non-fatal encephalitis due to other viruses, (iii) 16 patients with immune-mediated neurological diseases, and (iv) 15 patients with non-viral central nervous system infections and non-HTLV-I progressive spastic paraparesis. Levels of soluble interleukin 2 receptor (S-IL2R) were comparable in groups (i)-(iii). Fewer paralytic (1/6) than encephalitic (12/22) rabies patients had elevated S-IL2R. Only one patient with rabies and one with non-fatal viral encephalitis (group ii) had elevated S-CD8. Interleukin 6 (IL-6) was elevated in 5/22 rabies patients with encephalitis and in 0/6 paralytic rabies patients. Four individuals in groups (ii) and (iii) had elevated IL-6. Patterns of cytokine responses in group (iv) were similar to those in groups (i)-(iii). The results suggest defects in immune responsiveness in paralytic rabies.

Field study of an antigen-detection ELISA specific for Plasmodium falciparum malaria

We field-tested a specific antigen-detection enzyme-linked immunosorbent assay (ELISA) based on the histidine-rich protein of Plasmodium falciparum, in a district hospital in Thailand. The test was simple to perform, takes less than 3 h to complete, can deal with batches of sera, be read visually, and was 98.05% sensitive and 96.22% specific. However, 3 of 154 microscopically identified P. falciparum cases gave false negative ELISA results. One of these patients had been admitted to hospital for P. falciparum malaria 3 months previously and all 3 came from hyperendemic villages and were thought to have had previous episodes of malaria, possibly resulting in high titres of circulating blocking antibody. The test was more sensitive when whole blood was frozen and thawed before testing. This test is promising but requires further refinement to eliminate false negatives before it can be used safely for screening acutely ill patients for falciparum malaria. The sensitivity of this ELISA appears to be sufficiently high to consider it as a tool for blood donor screening in regions with a high prevalence of P. falciparum carriers with low parasitaemia. There is at present no satisfactory routine screening method for large numbers of blood donors for malaria.

Cells with natural killer activity in human rabies

Cytotoxic lymphocyte function in 13 patients with rabies was studied by counting the number of CD56 cells and assessing natural killer (NK) cell activity. There was no significant difference in the number of killer cells between rabies patients and 31 normal controls (P greater than 0.05). Two of six non-fatal encephalitic patients due to causes other than rabies had reduced CD56 numbers. Base-line NK cell responses versus K562 cell targets did not differ among the normal control and rabies groups (P greater than 0.05). Study of the non-rabies encephalitis group showed heterogeneous results with wide variation. Significant enhancement of NK activity was seen in four rabies patients and in 10 normal control subjects tested after interferon-alpha (IFN-alpha) and IL-2. None of the four patients with encephalitis due to causes other than rabies showed such enhancement. Our results suggest that NK cells of rabies patients are not fully stimulated and that this might contribute to the virulence of rabies. The cause of this phenomenon remains unknown.

Is injection of contaminated animal bite wounds with rabies immune globulin a safe practice?

In Asia, it is still controversial whether it is safe to inject a contaminated animal bite wound with a foreign protein such as equine or human rabies immune globulin, even though this is recommended by the World Health Organization. A prospective study of 114 severe animal bite wounds which were injected with equine or human rabies immune globulin revealed an overall incidence of gross infection of 11.4%. No matched control group of patients bitten by animals whose wounds were not injected with immune globulin could be studied in this environment with a high prevalence of canine rabies. The incidence of wound infection in lacerations inflicted by sharp objects and sutured under local anaesthesia was therefore studied prospectively in 100 Thai patients from a similar socio-economic milieu; it was found to be 13%. Wound infection was more common in animal bites and lacerations of the lower extremities. It is concluded that injecting a properly cleansed bite wound with equine or human rabies immune globulin is a safe practice and should be performed whenever there is a possibility that the biting animal might have rabies.

Murine and scrub typhus at Thai-Kampuchean border displaced persons camps

Rickettsial infections are considered a major cause of illness among inmates of Thai-Kampuchean border displaced persons camps. In the absence of sophisticated laboratory support, it had become common practice to treat patients with obscure fevers with tetracycline as a 'diagnostic' test for typhus. This study evaluated a group of 67 randomly selected camp inmates who presented with fever and had findings that indicated a specific diagnosis. Differential blood counts, malaria smears, hemoglobin determinations, blood cultures, dengue and Japanese encephalitis virus and rickettsial IgM and IgG antibody titers were determined. Patients were then treated with tetracycline and followed. They could be divided into six groups after data were analyzed. Those with no final diagnosis comprised 14 cases (21%), 4 patients (6%) were found to have dengue fever, 6 (9%) scrub typhus and 39 (58%) had murine (endemic) typhus. None of the bacterial blood cultures drawn from this group grew any organisms and no tick typhus or Japanese encephalitis was diagnosed. Analysis of symptoms and signs did not allow clinical differentiation between groups. All patients became afebrile and well within 1-5 days of starting tetracycline therapy. We conclude that rickettsial disease is a major health problem in the Thai-Kampuchean border camps. The incidence of murine typhus increased during the dry season and was more prevalent among males. The use of tetracycline as a 'therapeutic test' did not distinguish between rickettsial, viral and undiagnosed febrile diseases.

Immune response to rabies vaccine in Thai dogs: a preliminary report

Serum neutralizing antibody to rabies virus was determined in previously unvaccinated Thai pet dogs after receiving one subcutaneous dose of inactivated tissue culture rabies vaccine (Rabdomun, Coopers Animal Health Company, Germany, 4.55 IU ml-1 potency). Geometric mean titres on days 14, 30, 60, 180 and 360 were 2.14, 2.30, 0.45, 0.14 and 0.05 IU ml-1, respectively, by the rapid immunofluorescent focus inhibition test. Titres of neutralizing antibody to rabies virus did not correlate with the age of the dog at the time of vaccination or with the presence or absence of anaemia or blood parasites. Six out of 50 (12%), 11 out of 43 (25.6%) and 13 out of 31 (42%) dogs had no detectable rabies antibody in serum 60, 180 and 360 days, respectively, after vaccination. Three of these antibody-negative dogs were given another dose of vaccine. Antibody reappeared on day 14 but rapidly declined within 60 days. These data suggest that one dose of tissue culture vaccine in dogs by the subcutaneous route of injection is not adequate to maintain rabies neutralizing antibody in serum for 1 year.

One-year study of the 2-1-1 intramuscular postexposure rabies vaccine regimen in 100 severely exposed Thai patients using rabies immune globulin and Vero cell rabies vaccine

The 2-1-1 rabies postexposure treatment schedule is an abbreviated regimen in which a tissue culture rabies vaccine is administered intramuscularly at two sites on day 0, and at one site on days 7 and 21. Compared to the standard five-dose intramuscular regimen, the 2-1-1 schedule reduces the number of clinic visits from five to three and the amount of vaccine used by 20%. One hundred Thai patients, who were severely exposed to rabies, were treated with rabies immune globulin and the 2-1-1 regimen using purified Vero cell rabies vaccine. They were followed for 1 year. Rabies antibody titres were measured in 10% of this group. All patients survived and adverse reactions were mild. A satisfactory antibody response (a titre greater than 0.5 IU ml-1) occurred in all ten patients studied at day 14, but persisted for 90 days in 80% and for 360 days in only 50%. The authors therefore do not recommend use of the 2-1-1 schedule in severely exposed patients who also need to receive rabies immune globulin.

Rabies in Thailand: 1990

Of the more than 100,000 courses of postexposure rabies treatment given in Thailand annually, 95% consist of brain tissue-derived vaccine without immune globulin. Rabies tissue culture vaccines and immune globulins are expensive by the standards of developing countries. When they are given according to either of two proven intradermal postexposure schedules, significant savings can be achieved without loss of efficacy. Purified equine rabies immune globulins account for approximately 10% of the cost of human products administered to exposed individuals and have been shown to be safe and effective. A canine preexposure immunogenicity study with a potent, inactivated tissue culture vaccine revealed that 12.5% of Thai dogs failed to develop protective antibody titers 2 months after one subcutaneous injection. Previous studies have shown significant antigenic differences between Thai street rabies virus and European and North African strains.

Acridine orange fluorescent microscopy and the detection of malaria in populations with low-density parasitemia

Detection of low-density malaria parasites with Giemsa-stained thick smears (G-TS) requires time and experience and becomes impractical with high sample loads. Acridine orange fluorescent microscopy (AO/FM) of capillary centrifuged blood may offer an alternative technique. We compared AO/FM readings with G-TS in 290 specimens from asymptomatic people in Thai villages endemic for malaria. AO/FM specimens were prepared in modified capillary tubes coated with acridine orange (Quantitative Buffy Coat or "QBC tubes") and examined under a fluorescent microscope. Twenty-three (85.2%) of the 27 specimens found positive by G-TS had under 100 parasites/microliters blood (less than 35 parasites/200 microscopic fields). The overall AO/FM sensitivity was 78.9% [range: 66.7% (10/15)-86.7% (13/15)]. For Plasmodium falciparum, regardless of stages, the sensitivities varied from 66.7% (8/12) to 91.7% (11/12). AO/FM performed better for P. falciparum than for Plasmodium vivax and for asexual than for sexual stages of the parasite. However, the species- and stage-specific results must be interpreted with caution because of the small sample sizes and very low parasite densities involved. The test specificity was 96.6% [range: 95.6% (263/275)-97.1% (263/271)]. These levels of accuracy plus the known advantages of AO/FM suggest that the test, supplemented with G-TS to improve species and stage differentiation, is also useful for screening low-density parasitemias.

Detection of Plasmodia in acridine orange stained capillary tubes (the QBC system)

The sensitivity, specificity and convenience of carrying out malaria diagnosis in acridine orange stained capillary tubes using a fluorescent microscope (the QBC system) was compared to screening for Plasmodia on conventional Giemsa stained thick smears. A dilution study revealed that the QBC is able to detect Plasmodia in as low a dilution as 5 organisms per ul. The QBC system was evaluated at a district hospital in Thailand. A preliminary study of 186 patients compared the QBC system to the routine malaria screening procedure (screening up to 30 microscopic fields on a thick smear). The sensitivity of the QBC was found to be 98.9% with a specificity of 94.4%. A second combined series of 465 febrile subjects were screened by thick smear and these results were compared to the QBC. 202 were positive for malaria on both QBC and thick smear. Sensitivity in this study was found to be 99.5% (202/203) and the specificity was 94.6% (248/262). When both series were combined, there were 14 QBC malaria positives that were not detected on thick smear, and 2 QBC malaria false negatives among the 651 patients studied. The parasite densities in these cases were between 10 and 320,000 organisms/microliters. The QBC system provided only a crude estimate of the level of parasitemia. The species of Plasmodia (P. falciparum and P. vivax) were correctly identified on QBC in 78% of cases.

Postexposure prophylaxis for rabies with antiserum and intradermal vaccination

The Thai Red Cross intradermal postexposure rabies treatment schedule was prospectively assessed in 100 Thai patients severely bitten by proven rabid animals. It consists of 0.1 ml of purified Vero cell rabies vaccine containing more than 2.5 IU of rabies antigen per 0.5 ml of reconstituted vaccine given intradermally at two sites on days 0, 3, and 7, followed by one 0.1 ml injection on days 30 and 90. The commercial vaccine used had an antigen content of 3.17 IU per 0.5 ml ampoule. Purified equine or human rabies immuno-globulin was also given on day 0 to patients with severe exposures. As much of the immunoglobulin as possible was infiltrated around the wounds. All patients were followed for 1 year post exposure. There were no deaths; the efficacy of the regimen was 100%. Antibody titre determination in a randomly selected subgroup showed seroconversion in all 10 patients.

Equine rabies immune globulin: a product with an undeserved poor reputation

Four hundred nineteen patients exposed to rabies in Thailand were treated with equine rabies immune globulin (ERIG) manufactured by Sclavo of Italy, a product also licensed in the United States of America. They were followed for a minimum of 1 month after ERIG injection and rabies vaccine administration. Adverse serum sickness-like reactions were noted in 15 patients (3.58%). These were clinically acceptable and only 1 of these patients required corticosteroid therapy and short term hospitalization for serum sickness. ERIG is approximately 1/10 of the cost of human rabies immune globulin (HRIG), which is not generally available in developing countries. ERIG is a safe and underutilized essential biological when HRIG is not affordable or available.

What happens if intradermal injections of rabies vaccine are partially or entirely injected subcutaneously?

Reported are the results of a study with the Thai Red Cross two-site intradermal purified Vero-cell rabies vaccine (PVRV) schedule that was deliberately injected into subcutaneous tissue. The 44 healthy nonimmune Thai adults who were enrolled in the study were randomly assigned to the following groups and given PVRV as shown: group A (two intradermal injections on days 0, 3, and 7); group B (one intradermal and one subcutaneous injection on days 0, 3, and 7); and group C (two subcutaneous injections on days 0, 3, and 7). Neutralizing antirabies antibody titres were determined on day 14 using the rapid fluorescent focus inhibition test. High rabies antibody titres were obtained for all three groups. These results suggest that the economical and safe Thai Red Cross intradermal PVRV regimen could be used in selected general health care facilities.

Postexposure rabies vaccination during pregnancy: experience with 21 patients

Twenty-one pregnant rabies exposed patients received postexposure vaccination using purified Vero cell rabies vaccine. Twelve of these with severe exposures were also given equine rabies immune globulin. Adverse reactions were mild, transient and required no treatment. Fifteen per cent of the patients reported side-effects such as myalgia, malaise, erythema and swelling at injection sites, urticarial rashes, and mild regional lymphadenopathy. The vaccine series was completed in all cases and none of the mothers or infants developed rabies after one year of follow-up. No congenital malformations were detected. All infants were well after one year. One patient experienced a spontaneous abortion.

Adverse effects of equine rabies immune gobulin

Following a recently published prospective study of 485 recipients of equine rabies immune globulin (ERIG) manufactured by Pasteur Vaccins (Paris), this paper reports a study of 323 postexposure rabies patients receiving ERIG manufactured by the Swiss Vaccine and Serum Institute (Berna). It is concluded that there may be significant differences in adverse reaction rates, reflecting differing manufacturing or purification processes and protein content. Further studies of different ERIG products and of different lots of the same product are needed while ERIG remains an essential component of postexposure rabies treatment in developing countries.

Failure of rabies postexposure treatment in Thailand

Three failures of postexposure rabies treatment using imported purified duck embryo cell and Vero cell rabies vaccines are reported from Thailand. Reference is made to eight additional previously reported Thai patients, six of whom had received human diploid cell vaccine. An analysis of these cases reveals that there were serious flaws in management in all of these patients. It is stressed that 45% of human rabies deaths in Thailand occur within 20 days of being bitten and 71% are dead within 28 days. This short incubation period does not allow much time to start immunotherapy. Of Bangkok dogs found to have rabies at autopsy, approximately 8% have a rabies immunization history. Once a dog has bitten a patient immunotherapy should not be delayed in countries with a high incidence of dog rabies. Patients with chronic disease, alcoholics and drug addicts may have an impaired immune response to postexposure rabies vaccines.

Purified equine rabies immune globulin: a safe and affordable alternative to human rabies immune globulin

Reported are the results of a retrospective study of 3156 patients who were treated at the Queen Saovabha Memorial Institute, Bangkok, with equine rabies immune globulin (ERIG). Only 51 patients (1.6%) exhibited serum-sickness-like reactions, none of which persisted for more than a week, and only 8 of these patients (15%) were treated with a short course of steroids. One patient, whose skin test was negative, had an immediate anaphylactic reaction to ERIG that responded to parenteral therapy with epinephrine and hydrocortisone sodium succinate. Serum-sickness-like reactions were more frequent among females and over 21-year-olds but were exceedingly rare (0.086%) among children under 10 years of age.

Acceptability and efficacy of purified vero-cell rabies vaccine in Thai children exposed to rabies

A field trial of purified vero-cell tissue culture rabies vaccine (PVRV) was carried out, and 566 children under 15 years of age were studied. Of these 309 (54.6%) had been exposed to laboratory proven rabid animals. Rabies immune globulin (RIG) was given to 47 children with severe exposures. The vaccine was given by the conventional six-dose intramuscular route to 467 patients (82.5%). The remaining 99 victims (17.5%) were given vaccine by the multiple site intradermal route using a schedule of 0.1 ml at two sites on days 0, three and seven, and at one site on days 30 and 90. Adequate follow-up was achieved in 100% of the cases with proven exposure to rabid animals at three months, and in 94.1% at one year. The overall follow-up rate for the entire group was 91.1% at the end of one year, and all patients traced were alive and healthy. The incidence of minor adverse reactions to PVRV was equal to that of other tissue culture rabies vaccines. Regional lymphadenopathy and itching at the injection sites were significantly more common in the group receiving intradermal vaccine than in those who received vaccine by the intramuscular route.

The influence of 1,2,4-benzotriazine derivatives on the apparent viscosity of human blood

Some benzotriazines markedly reduce human whole-blood viscosity. Viscosity was measured electronically with a novel capillary viscosimeter. Because of the increasing interest in hemorheologically active drugs, the compounds merit further investigation.

A report of three cases of AIDS in Thailand

Acquired immune deficiency syndrome (AIDS) has been rarely reported as occurring primarily in Asia. We report here on first three cases of AIDS diagnosed at Chulalongkorn Hospital Medical School. One case was an American who had been in Thailand for two years; the other two were Thai. The American and one of the Thai patients were male homosexuals but they had no connection with one another. The latter Thai male homosexual had sexual contact with a German man who showed no evidence of the disease. The other Thai patients was the mistress of the male Thai patient, which underlies the importance of heterosexual transmission of the disease. The two male patients had opportunistic infections whereas the female patient had only generalised lymphadenopathy (Pre-AIDS). Delayed type hypersensitivity response, T-cell subsets enumeration and the in vitro T-cell mitogen response served as diagnostic tools when combined with the clinical history. The diagnosis was made even before the results of tests to determine the presence of antibodies to HTLV-III were known. The presence of anti-HTLV-III simply confirmed our diagnosis.

Doctoring in eastern Europe

Health care in Eastern Europe has not achieved world standards nor the goals of planners of socialist societies. With luck, perseverance, bribes or good connections, it is possible to obtain good medical and surgical care in Eastern Europe for a major illness. Primary and even secondary care usually are substandard, however, and often completely unacceptable to most Western foreigners. The reasons for this are complex but mainly rooted in different attitudes of health workers towards their patients, poor physical plants, poor salary structures, inadequate advancement opportunities for health care workers, poor social status and professional recognition for nurses and almost complete isolation of the average primary care doctor from hospital medicine.

Surgical management of an epidemic of penile amputations in Siam

Thailand recently experienced an epidemic of penile amputations. These were usually performed by angry wives on philandering husbands. This outbreak appeared to have been fueled by graphic press reports and fortunately seems to have abated. A technique for reanastomosis of the amputated penile segment was first described by McRoberts et al [5] in 1968. It was modified further so that it can be performed in any general hospital with an acceptable result. Experience with this procedure in 18 patients has been described.