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Biomedical subjects

H Wilde

Publications and source records attributed to H Wilde.

At least 91 records · Page 5Linked to original sources

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.

Animals↗

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.

Adolescent↗

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.

Adolescent↗

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.

Animals↗

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.

Adolescent↗

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.

Acridine Orange↗

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.

Cambodia↗

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.

Adolescent↗

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.

Adolescent↗

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.

Acridine Orange↗

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.

Adolescent↗

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.

Animals↗