Towards developing a diagnostic regimen for the treatment follow-up of Trypanosoma brucei gambiense

BALB/c mice infected with a high virulent strain of Trypanosoma brucei gambiense IL3707 were treated intraperitoneally (i.p.) with either Melarsoprol (Mel-B) or PSG(+) buffer as controls. The mice were subsequently monitored regularly for parasites by direct microscopic examination of their tail blood or buffy coat and by polymerase chain reaction (PCR). Mel-B was found to be an effective drug for treatment against T.b. gambiense because at the end of the first treatment schedule, all treated mice were negative for parasites even by PCR, while all the control animals were positive. Three of the five Mel-B treated mice, while parasitologically negative, were PCR positive between 53 and 80 days post infection (DPI), indicating that they still harbored an infection. All treated mice were subsequently negative for parasites even by PCR at 88 DPI. A combination of conventional microscopic examination and PCR offers a good prediction of cure following treatment of trypanosomosis.

African trypanosomiasis in two travelers from the United States

African trypanosomiasis is a rare but well-documented cause of fever in United States travelers returning from areas where it is endemic. We report two recently diagnosed cases that involved tourists who went on safari in Tanzania. Review of these and 29 other published cases indicates that disease in returning United States travelers is nearly always of the East African form, a fulminant illness for which prompt diagnosis is necessary. In the United States, timely and appropriate therapy for this disease has resulted in favorable outcomes for most patients. Chemoprophylaxis for East African trypanosomiasis is not recommended, but travelers visiting areas of endemicity should practice appropriate preventive measures to prevent tsetse fly bites.

Rhodesian trypanosomiasis in a splenectomized patient

We report the first apparent case of a splenectomized individual who developed severe trypanosomiasis with central nervous system involvement. The patient was a 41-year-old man who participated in an east African safari. Upon his return to the United States, the patient presented with an infection with Trypanosoma brucei rhodesiense that was treated successfully with suramin and melarsoprol. The onset of symptoms, laboratory studies, and disease progression did not differ from previously reported cases in the literature. The role of the spleen in trypanosomiasis is not well understood and the few reports available describe only animal models. This report suggests that asplenia had no apparent effect on the onset of symptoms and overall severity of illness. Further studies are necessary to ultimately define the role of the spleen in trypanosomiasis.

Reversal of the sleep/wake cycle disorder of sleeping sickness after trypanosomicide treatment

To determine whether the circadian disruption of the sleep/wake cycle observed in sleeping sickness, human African trypanosomiasis (HAT), can be reversed after trypanosomicide treatment, 10 Congolese patients infected by Trypanosoma brucei gambiense underwent 24-h polysomnographic recordings before treatment with melarsoprol and after each of three weekly treatment sessions. Polysomnography consisted of a continuous recording of the electroencephalogram, electromyogram and electro-oculogram on a Minidix Alvar polygraph. Sleep traces were analysed in 20-sec epochs for wakefulness, REM sleep, and NREM sleep [stages 1, 2, 3, 4; stages 3 and 4 representing slow-wave sleep (SWS)]. As previously described (Buguet et al. 1993), the 24-h distribution of the sleep/wake cycle was disturbed proportionally to the severity of the illness. The overall amounts of each sleep/wake stage did not change after treatment. However, the patterns of occurrence of sleep episodes, REM sleep and SWS phases were determinant in the evaluation of treatment efficacy. The trypanosomicide action of melarsoprol led to a reduction in the number of sleep episodes, except in one patient whose health condition worsened during the third treatment session: sleep onset REM sleep phases (SOREMPs) decreased and the number of SWS episodes during a sleep episode increased. We conclude that in HAT, the reversibility of the sleep/wake cycle alteration and that of sleep structure constitute the basis for an evaluation of the healing process.

[Therapeutic failure of melarsoprol among patients treated for late stage T.b. gambiense human African trypanosomiasis in Uganda]

The failure rate of melarsoprol after treatment of late stage cases of Human African Trypanosomiasis (HAT) is usually under 7%, even though the drug has been used for such treatment over the past 50 years. We report a melarsoprol treatment failure rate of 26.9% among 428 patients treated in Northern Uganda. Whatever its origin, this observation, the first documented in a HAT focus, is alarming, particularly since no second line trypanocidal drug is actually available for the treatment of late stage HAT. We believe that the current worrisome situation of HAT in several African countries and the risk of emergence of other foci of resistance, argue in favour of a greater attention on the part of the scientific community and the pharmaceutical companies being paid to this problem.

Is sleeping sickness a circadian disorder? The serotonergic hypothesis

Patients with human African trypanosomiasis (HAT, sleeping sickness), due to the inoculation of Trypanosoma brucei gambiense or rhodesiense by the tsetse fly, are "sleepy by day and restless by night." The first 24 h polysomnographic recording (electroencephalogram [EEG], electromyogram [EMG], electrooculogram [EOG]), showing a disappearance of the 24 h rhythmicity of sleep and wakefulness, was performed in 1988. Thereafter, our team recorded 18 patients and 6 control volunteers at bed rest during 24 h sessions. Blood samples were taken hourly from 8 of the patients through a venous catheter and every 10 minutes from the remaining 10 patients. Plasma cortisol, prolactin, growth hormone (GH), melatonin, and plasma renin activity were analyzed. No disruptions of the circadian rhythms of sleep and wakefulness were described in the 6 healthy African subjects, and there also were no disturbances of 24 h hormone profiles. The patients experienced a dysregulation of the circadian rhythmicity of sleep and wakefulness that was proportional to the severity of the disease. Sleep onset rapid eye movement (REM) episodes were more frequent in the most severely sick patients, who also showed major disruptions in the 24 h plasma hormonal profiles, with intermediate profiles being observed at earlier stages of the sickness. However, the relationship between hormonal secretions and the states of vigilance persisted. Contrary to the other hormones, melatonin secretion remained undisturbed. These findings indicate that, at the stage of meningoencephalitis, HAT represents a dysregulation of the sleep-wake cycle and sleep structure, rather than a hypersomnia; this dysregulation is proportional to the degree of severity of the clinical and biological symptoms. It is accompanied by a circadian dysrhythmia of hormonal secretions, although the relationship between hormone pulses and sleep states is preserved. We therefore favor the involvement of the serotonergic raphe nuclei-suprachiasmatic nuclei liaison in the reversible disturbance of the circadian rhythms of the sleep-wake cycle and of hormonal secretions.

Risk factors for treatment failure after melarsoprol for Trypanosoma brucei gambiense trypanosomiasis in Uganda

We evaluated the treatment failure rate among late-stage human African trypanosomiasis (HAT) patients treated with melarsoprol in Arua, northern Uganda, between September 1995 and August 1996, and identified the risk factors for treatment failure. We conducted a retrospective cohort study in October 1998, and performed a survival analysis. A treatment failure was defined as a late-stage HAT patient fully treated with melarsoprol and classified as an HAT case at any follow-up visit within 2 years after treatment. Among 428 patients treated in the study period, 130 (30.4%) were identified as treatment failure within 2 years after discharge. The multivariate analysis showed that patients who experienced treatment failure after melarsoprol were more likely to have been admitted as a relapsing case (relative hazard, RH = 11.15 [6.34-19.61]), and to have been diagnosed with trypanosomes in the lymph nodes (RH = 3.19 [2.10-4.83]) or in the cerebrospinal fluid (CSF) (RH = 1.66 [1.09-2.53]). The risk of treatment failure also increased with the number of cells in the CSF. The treatment failure rate after melarsoprol observed in Arua is greatly above the expected figures of 3-9%. More research is needed to confirm whether it is related to the variation of melarsoprol pharmacokinetics between individuals, or if it is associated with a reduced susceptibility of the trypanosomes to melarsoprol. The study emphasizes the need for second-line drugs to treat patients that have already received one or several full course(s) of melarsoprol.

Use of polymerase chain reaction in human African trypanosomiasis stage determination and follow-up

Stage determination of human African trypanosomiasis is based on the detection of parasites and measurements of biological changes in the cerebrospinal fluid (CSF) (concentration of white blood cells > 5 cells per mm3 and increased total protein levels). The patient is treated accordingly. Demonstration of the absence or presence of trypanosomes by the double centrifugation technique is still the only test available to clinicians for assessing treatment success. In this study, however, we evaluate the polymerase chain reaction (PCR) as a tool for assessing the disease stage of trypanosomiasis and for determining whether treatment has been successful. All 15 study patients considered to be in the advanced stage of the disease were PCR positive; however, trypanosomes were demonstrated by double centrifugation in only 11 patients. Of the five remaining patients, who were considered to be in the early stage, PCR and double centrifugation were negative. Following treatment, 13 of the 15 second-stage patients were found to be negative for the disease in at least two samples by PCR and double centrifugation. Two others were still positive by PCR immediately and one month after the treatment. Trypanosome DNA detection using PCR suggested that the two positive patients were not cured but that their possible relapse could not be identified by a search for parasites using the double centrifugation technique. Further evaluation of the PCR method is required, in particular to determine whether PCR assays could be used in studies on patients who fail to respond to melarsoprol, as observed in several foci.

[In vivo resistance to strains of Trypanosoma rhodesiense, Mozambique, 1985]

We report the existence of high resistance to Melarsoprol and low resistance to Suramin in 11 Trypanosoma rhodesiense species. They were isolated from humans in the Tete province, Mozambique, and kept in mice at the Maputo National Health Institute. The preliminary results obtained with Suramin administered intracranially, are also reported.

[Current status of trypanosomiasis]

Sleeping sickness is presently undergoing a recrudescence mainly as a result of major socioeconomic problems in Africa. Despite the reigning pessimism due to the currently unfavorable context (increasing incidence, lack of rapid diagnostic criteria, and unavailability of active non-toxic therapeutic agents), research data hold the promise of more effective control of this disease in the future. Mapping of infected households is now necessary to allow better early identification and follow-up of patients. Great advances have been made in the study of the pathogenesis of nervous involvement and it has been demonstrated that the characteristic symptoms of sleeping sickness are due to penetration of trypanosomes into the central nervous system (CNS) through the blood-brain barrier. However an unsolved problem is determining whether the blood-brain barrier has been broken and CNS involvement has occurred. This determination is important because neurologic involvement is a prerequisite for deciding when to undertake treatment using highly toxic melarsoprol. Research to identify new criteria for staging blood/lymph and nervous involvement is under way and encouraging results have been obtained using auto-antibodies against nervous system components. Although there is now greater hope that a vaccine will be developed in the future, treatment has not advanced greatly in the last 50 years. Pentamidine can be effective in some patients with "early-stage" nervous involvement. Melarsoprol is fatal in about 5% of patients treated. New drugs (e.g. nitroimidazoles) may become available one day but development is slow because most research is being done in a few university laboratories.

Attempt to correlate urine arsenic excretion with clinical course during melarsoprol therapy of patients with Rhodesian trypanosomiasis

This study enrolled 28 CNS-involved patients with Trypanosoma brucei rhodesiense at the Kenya Trypanosomiasis Research Institute (Alupe, Kenya) to examine treatment efficacy and toxicity of melarsoprol in relation to renal excretion/dose relationships. This study complied with World Health Organization treatment recommendations, initially treating with suramin followed by three courses of melarsoprol. Traced study patients had a relapse rate of 4.1%. The toxicity and crude death rate was 7.1%. Total urine arsenic output was measured between 24 and 48 hr after the last dose for each course. The range of means of total urine arsenic output between the three treatment courses was 356-511 micrograms. There was no correlation comparing melarsoprol dose, estimated creatine clearance, or urine arsenic output. Urinary pharmacokinetic parameters are not predictive of toxicity or therapeutic efficacy.

Effect of melarsoprol treatment on circulating IL-10 and TNF-alpha levels in human African trypanosomiasis

The pathogenesis of human African trypanosomiasis (HAT) has been the object of considerable research interest but has remained incompletely understood. The importance of cytokines in the pathophysiology of this protozoan infection is now widely recognized, but the full spectrum of cytokines involved has yet to be determined. In the present investigation we compared the plasma concentrations of TNF-alpha and IL-10 in normal African controls and patients suffering from advanced meningocephalic (late-stage) Trypanosomiasis brucei (T.b.) gambiense infections, before and after treatment with the arsenical trypanocide melarsoprol. We found that patients with late-stage T. b. gambiense exhibit chronically elevated circulating levels of both of these cytokines, and that these levels quickly decline following melarsoprol treatment. These findings confirm that TNF-alpha is involved in the immunopathogenesis of late-stage African trypanosomiasis and suggest that IL-10 may also play an important regulatory role in this disease.

Endotoxin antibodies in African sleeping sickness

Antibodies to the core region of endotoxin (endotoxin core antibodies, EndoCAb), which cross-react with endotoxin from a range of Gram-negative bacteria, are maintained in relative homeostasis in health, but undergo marked changes in a number of different diseases associated directly or indirectly with endotoxaemic or septicaemic states. The levels of EndoCAb IgG in the blood and cerebrospinal fluid (CSF) of 35 late-stage sleeping sickness patients and 9 control individuals were measured by ELISA. EndoCAb levels were significantly elevated in the patient blood (mean EndoCAb value 290 MU/ml cf. control 182 MU/ml, P < 0.001), and CSF (mean EndoCAb value 254 MU/ml cf. control 150 MU/ml, P < 0.001). EndoCAb IgG levels correlated with endotoxin levels in patient blood (r = 0.78, P < 0.001), but not in the CSF and were not reduced 6 weeks following chemotherapy, unlike the endotoxin levels. It is concluded that late-stage sleeping sickness is associated with chronic exposure to endotoxins from Gram-negative bacteria.

In vivo evaluation of sixteen plant extracts on mice inoculated with Trypanosoma brucei gambiense

After examination of the drugs used by traditional practitioners in Côte d'lvoire, nine formulas prescribed in the treatment of African human trypanosomiasis (AHT) were selected for investigation. These formulas made use of 40 plants, 16 of which were studied because of their properties, as described in the literature, and their frequent use by practitioners. The plant extracts were administered, after maceration or decoction, either orally or intraperitoneally to Swiss mice that had previously been inoculated with Trypanosoma brucei gambiense (Tbg), strain MHOM/Cl/81/Dal 083. The parasitaemia in each mouse was followed for three consecutive days and compared with that in control mice, which had been given either a saline solution (SS: negative control) or well-known drugs (melarsoprol, difluoromethylornithine, and pentamidine: positive control). Our investigations led to the following conclusions. (a) None of the plant extracts revealed trypanocidal or trypanostatic activity relative to SS controls (P > 0.05). In fact, the mice that received the extracts died on the third day after inoculation, with 0% survival and an average parasitaemia of 10.8 +/- 2 x 10(7) trypanosomes/ml. (b) The treated positive controls, relative to SS, showed 100% survival and no parasitaemia (P < 0.05). Melarsoprol appeared to be active when given orally at a dose of 3.6 mg/kg body weight twice a day for 3 days. This method of testing the sensitivity of trypanosomes to plant extracts is easy and inexpensive, and could be applied to other areas of research on tropical diseases.

The importance of 2,3-dimercaptopropinol (British anti-lewisite, BAL) in the trypanocidal activity of topical melarsoprol

Both melarsomine dichlorhydrate (mel Cy, Cymelarsan) and melarsen oxide can be dissolved in dimethylsulfoxide and converted into a gel by the addition of hydroxypropylcellulose. When Trypanosoma brucei brucei-infected mice are treated topically with these gels the circulating trypanosomes are rapidly cleared from the circulation but the infections relapse soon after the last application. However, when these two compounds are allowed to react with 2,3-dimercaptopropinol (British anti-lewisite, BAL) and form "melarsoprol" their efficacy, especially in the case of mel Cy, is restored to that of commercial melarsoprol (Arsobal) and trypanosomes in the central nervous system (CNS) can be eliminated. This would indicate that the dimercaptopropinol portion of the molecule does not act solely as an "antidote" to arsenic toxicity, but also plays an important role in the absorption of melarsoprol through the skin and/or blood-brain barrier into the CNS and/or into the trypanosome.

Cost-effectiveness analysis of alternative treatments of African gambiense trypanosomiasis in Uganda

African trypanosomiasis, or sleeping sickness, is a tropical disease caused by trypanosome parasites transmitted by tsetse flies. The focus of this paper is on the cost-effectiveness of alternative drug treatments for patients in the late stage of the disease. Melarsoprol has been used for many decades. More recently, eflornithine has been developed. It has fewer side effects and improves the overall cure rate. It is much more expensive than melarsoprol, however. The objective of the present cost-effectiveness is to identify the costs and benefits that would be involved in switching from melarsoprol to eflornithine in the treatment of late stage sleeping sickness. Benefits are expressed in lives saved as well as in disability adjusted life years (DALYs). The analysis is applied to the case of Uganda. The implications for affordability are also considered, by taking account of how the treatment costs would be shared between the national government, donors and patients. The baseline results indicate that melarsoprol treatment is associated with an incremental cost per life and DALY saved of $209 and $8, respectively. Each additional life saved by switching from melarsoprol alone to a combination of melarsoprol and eflornithine would cost an extra $1,033 per life saved, and an extra $40.9 per DALY gained. Shifting from this second alternative to treatment of all patients with eflornithine leads to an incremental cost per life saved of $4,444 and an incremental cost of $166.8 per DALY gained.

Alternative application of melarsoprol for treatment of T. B. gambiense sleeping sickness. Preliminary results

The protocols for treatment of human African trypanosomiasis (sleeping sickness) with the organoarsenical drug melarsoprol are based on empirical observations. Therapy is often accompanied by serious side effects and relapses. Additionally, the duration of treatment, which is up to forty days, is a major drawback in African countries. Based on pharmacokinetic investigations an alternative therapy protocol for T. gambiense sleeping sickness has recently been proposed which consists of ten consecutive injections of 2.2 mg/kg melarsoprol given at intervals of 24 hours. In a preliminary study, eleven patients were treated in Vanga, Zaire following this alternative protocol which reduces the duration of the treatment to ten days. The results indicate that the alternative schedule was as effective as the traditional protocol, showed similar adverse reactions but required a much shorter treatment period.

Pharmacokinetics and adverse reactions after a single dose of pentamidine in patients with Trypanosoma gambiense sleeping sickness

1. Plasma concentrations of pentamidine were measured up to 1-8 months after a single 2 h i.v. infusion of 3.0 to 4.8 mg kg-1 pentamidine isethionate in 11 patients with late stage Trypanosoma gambiense sleeping sickness. 2. Maximum plasma drug concentrations varied between 713 and 2461 nmol 1-1. After termination of infusion, a rapid distribution phase over 10 min was followed by a slower distribution phase and an elimination phase prolonged over weeks to months. 3. The 'terminal' elimination rate constant could be determined in six patients and subsequent kinetic calculations showed a three to fourfold variation in plasma clearance and 'terminal' half-life (median 1126 (range 553-2036) ml min-1 and 265 (107-446) h, respectively). The median apparent volume of distribution (Vss) was 11,850 1. Renal clearance accounted for a median of 11% of total plasma clearance, indicating that metabolism is a major route of pentamidine elimination in man. 4. Side effects were few and mild and a slight or moderate decrease in blood pressure was the most common registered adverse reaction observed in four subjects. 5. The prolonged elimination of pentamidine seems inconsistent with the present recommended dosage regimen of pentamidine for treatment of trypanosomiasis of 7 to 10 parenteral doses given once daily or every second day.

[Polyneuritis and myositis in Trypanosoma gambiense infection]

During a four-week trip to Nigeria a 54-year-old German developed a fever of 39 degrees C. Later on he had lymphadenopathy, pretibial oedema, dyspnoea and weight loss. After 16 weeks a wreath-like pale pink skin rash, increased pulse rate with pulse deficit and hepatosplenomegaly were noted. Abnormal laboratory findings were an increased blood sedimentation rate (95 mm), raised immunoglobulin M (483 mg/dl), haemoglobin of 12.0 g/dl, mean corpuscular volume of 76 fl and Borrelia IgM antibody titre of 1:512. The electrocardiogram was suggestive of myocarditis: the cardiac symptoms were controlled with digoxin and verapamil. The patient's general condition deteriorated while he was receiving antibiotic treatment with tetracycline and penicillin. Cerebrospinal fluid (CSF) showed an increased cell count (39/microliters) and albumin (0.98 g/dl). There was a mild, predominantly proximal, tetraplegia which--on the basis of electromyographic and biopsy findings--was thought to be due to polyneuritis and myositis. At this stage blood smear and CSF examination revealed Trypanosoma. He thereupon received suramin (1.0 g) and prednisolone (120 mg down to 40 mg) daily, to which melarsoprol was added after 6 days (0.5 ml up to 5.0 ml daily for 36 days). Almost all symptoms then regressed within 6 weeks.

[Control of Trypanosoma gambiense trypanosomiasis. Evaluation of a strategy based on the treatment of serologically suspected cases with a single dose of diminazene]

A novel method for the control of T.b. gambiense trypanosomiasis was evaluated in an endemic focus of Zaïre where a high incidence had persisted despite massive participation in active case-finding surveys based on lymph node puncture. All inhabitants of 3 villages were examined with a card agglutination serological test (CATT), and parasitological examinations were performed on those who were CATT+. Individuals in whom we detected trypanosomes were treated as usual. A lumbar puncture was carried out on CATT+/parasitology- subjects; those whose cerebrospinal fluid showed more than 3 white blood cell (WBC) per mm3 were treated with a full course of melarsoprol while those with a CSF WBC count between 1 and 3 per mm3 were given a single injection of diminazene (7 mg/kg). Three such surveys were performed, with a 6-month interval, during which 282 "serological suspects" received diminazene, 39 "clinical cases" were given melarsoprol and 82 "parasitological cases" were treated according to standard protocols. The annual incidence of trypanosomiasis decreased rapidly from 10.4-41.1/1.000 inhabitants (mean: 17.6/1.000) during the 10 years before the intervention to 1.1-2.6/1.000 (mean: 1.7/1.000) in the 3 years following the intervention. No major adverse effect was seen with diminazene. Among the 282 serological suspects, an elevated CSF WBC count was later documented in 12 individuals, who were all cured with melarsoprol. The incidence increased 5 years after the intervention (7.1/1.000 in 1992), which may have been avoided had we carried out similar interventions in adjacent foci.