Influence of age, severity of infection, and co-infection on the duration of respiratory syncytial virus (RSV) shedding.

RSV is the most important viral cause of pneumonia and bronchiolitis in children worldwide and has been associated with significant disease burden. With the renewed interest in RSV vaccines, we provide realistic estimates on duration, and influencing factors on RSV shedding which are required to better understand the impact of vaccination on the virus transmission dynamics. The data arise from a prospective study of 47 households (493 individuals) in rural Kenya, followed through a 6-month period of an RSV seasonal outbreak. Deep nasopharyngeal swabs were collected twice each week from all household members, irrespective of symptoms, and tested for RSV by multiplex PCR. The RSV G gene was sequenced. A total of 205 RSV infection episodes were detected in 179 individuals from 40 different households. The infection data were interval censored and assuming a random event time between observations, the average duration of virus shedding was 11·2 (95% confidence interval 10·1-12·3) days. The shedding durations were longer than previous estimates (3·9-7·4 days) based on immunofluorescence antigen detection or viral culture, and were shown to be strongly associated with age, severity of infection, and revealed potential interaction with other respiratory viruses. These findings are key to our understanding of the spread of this important virus and are relevant in the design of control programmes.

Phosphorus budget in the low-income, peri-urban area of Kibera in Nairobi (Kenya).

Kibera, located in Nairobi, Kenya is one of the largest (235,000 inhabitants) low-income areas in East Africa. Surface waters in Kibera show high pollution levels with respect to SRP (soluble reactive phosphorus; range: 2-10 mg P/L), coming from the uncontrolled wastewater discharges in the area. The different P production and consumption values in Kibera were estimated using interviews (155 interviewed) as well as detailed P house-keeping for five representative families. The results show that highest P consumption comes from food, in particular cereals. Highest P production came from urine (55% of the total) and faeces (31%), with relatively lower contributions from grey water and solid wastes. The overall P budget in Kibera amounted to around 9 x 10(3) kg P/month. This is equivalent to 0.47 g P/person yr, both for P production and consumption, with a relative error of 20%. Comparing with the estimated P outflows via the Kibera surface waters, around 65% of the P produced in Kibera will leave the area. In future ECOSAN techniques such as urine separation could well be applied for efficient recycling of these waste sources.

In utero exposure to helminth and mycobacterial antigens generates cytokine responses similar to that observed in adults.

Neonates exposed to parasite antigens (Ags) in utero may develop altered fetal immunity that could affect subsequent responses to infection. We hypothesized that cord blood lymphocytes (CBL) from offspring of mothers residing in an area highly endemic for schistosomiasis, filariasis, and tuberculosis in Kenya would either fail to respond or generate a predominantly Th2-associated cytokine response to helminth and mycobacterial antigens (PPD) in vitro compared to maternal PBMC. Kenyan CBL generated helminth Ag-specific IL-5 (range 29-194 pg/ml), IL-10 (121-2,115 pg/ml), and/or IFN-gamma (78 pg/ml-10.6 ng/ml) in 26, 46, and 57% of neonates, respectively (n = 40). PPD induced IFN-gamma in 30% of Kenyan CBL (range 79-1,896 pg/ml), but little or no IL-4 or IL-5. No Ag-specific IL-4, IL-5, or IFN-gamma release was detected by CBL obtained in the United States (n = 11). Ag-driven cytokine production was primarily CD4-dependent. Cytokine responses to helminth and mycobacterial Ags by maternal PBMC mirrored that observed in neonates. CBL from helminth infected and/or PPD-sensitized mothers produced more Ag-specific cytokines compared to CBL from uninfected mothers (P < 0.05). These data demonstrate that the human fetus develops similar patterns of cytokine production observed in adults and indicates that prenatal exposure may not lead to tolerance or altered fetal immunity. .

Immunity in human schistosomiasis mansoni: cross-reactive IgM and IgG2 anti-carbohydrate antibodies block the expression of immunity.

We have previously reported that the slow development of immunity to reinfection after treatment of Schistosoma mansoni infections is partly attributable to the continued presence of 'blocking' antibodies in young, susceptible children. A further analysis of this phenomenon supports the hypothesis that such blocking antibodies can be of the IgG2 as well as the IgM isotype, and that they react with carbohydrate epitopes expressed both on egg polysaccharides and on schistosomulum surface antigens, of particular importance being those antigens that are shed from the schistosomulum surface during the early stages of maturation in vitro. Evidence is also presented that, in those patients lacking high levels of IgG2 blocking antibodies, resistance to reinfection after treatment is associated with the presence of other IgG isotypes against the same shed antigens.

T-lymphocyte subsets in idiopathic dilated cardiomyopathy.

Idiopathic dilated cardiomyopathy (IDC) is a common clinical problem in Africa. To determine if there is a defect of immune regulation in patients with IDC, the percentage of total T-cells (OKT3 positive), helper/inducer cells (OKT4 positive) and suppressor/cytotoxic cells (OKT8 positive) were measured using monoclonal antibodies in 20 patients with IDC and in 20 age-matched normal control subjects. The percentage of helper/inducer cells was significantly higher in the IDC patients (45 +/- 2% mean +/- standard error) than in the normal subjects (33 +/- 2%) and 8 of the 20 IDC patients had a helper/suppressor cell ratio (OKT4/OKT8) higher than the normal range. Of the 8 patients with this abnormality, 7 were studied within 3 months of the onset of their illness. Results suggest that an excessive immune reaction is part of the pathogenesis of IDC in Africans.

Subpopulations of T lymphocytes in Kenyan patients with visceral leishmaniasis.

Populations of peripheral blood T lymphocytes from patients with Kenyan visceral leishmaniasis were studied using specifically defined antisera (monoclonal antibodies, Ortho-mune OKT3, OKT4, OKT6, and OKT8). The levels of total T lymphocytes and circulating thymocytes were within the same range as those of clinically normal individuals. However, the proportions of the helper/inducer T cells were lower in untreated patients than in the controls (18.9% vs. 39.7%) while the levels of suppressor/cytotoxic T cells were higher than in the controls (40.5% vs. 27.8%). After successful antileishmania treatment these levels showed a gradual return towards normal over a period of one year. It was concluded that immunosuppression observed is due to the levels of peripheral blood helper/inducer and suppressor/cytotoxic T lymphocytes.

Chemotherapy-based control of schistosomiasis haematobia. IV. Impact of repeated annual chemotherapy on prevalence and intensity of Schistosoma haematobium infection in an endemic area of Kenya.

To determine the effect of repeated, annual, age-targeted therapy on prevalence and intensity of Schistosoma haematobium infection in an endemic area, we treated all available, infected, school-age children (n = 2, 493) in the Msambweni area of Coast Province, Kenya with a randomized protocol of oral metrifonate (10 mg/kg for three doses each year) or praziquantel therapy (40 mg/kg as a single dose each year) for a period of one to three years. During 1984-1987, 1, 101 children completed three years of therapy, 550 received two years, and 842 received a single year. Annual followup revealed significant long-term suppression of S. haematobium infection in the targeted school-age population. Both cross-sectional analysis and study of individual outcomes suggested maximal suppression of infection after two years of therapy. Suppression lasted more than two years after cessation of treatment, and was associated with reduced community transmission (gauged by decreased prevalence among new study entrants and decreasing negative-to-positive conversion on annual parasitologic examinations). Comparison of metrifonate and praziquantel outcomes indicated greater suppression of infection and longer infection-free intervals for some subgroups given praziquantel. We conclude that annual population-based therapy targeted to schoolchildren has direct and indirect beneficial effects for endemic communities. In some specific situations, repeat therapy may not suppress transmission, and reduced drug efficacy may be observed after one to three years, suggesting the need for additional non-drug control measures in highly endemic villages.

Contribution of adherent cells and serum components to immune suppression in Kenyan visceral leishmaniasis.

Adherent cells and serum components from Kenyan patients with visceral leishmaniasis were examined with the view to evaluating their contribution to cell-mediated immune suppression. Mitogens (phytohemagglutinin and concanavalin A) and antigens (purified protein derivative, streptokinase-streptodornase, and leishmania) were used as stimulants. Compared to the controls, the contribution of serum components to suppression in presence of any of the mitogens and antigens was not significant. The same applied to adherent cells, except in the presence of leishmania antigen where adherent cells contributed significantly (P less than 0.001). Removal of adherent cells from peripheral blood mononuclear cells of patients and controls considerably increased in vitro lymphocyte responses to both mitogens and antigens (by about twice), suggesting that in this study, the inhibition of in vitro lymphocyte responses to antigens and mitogens by adherent cells was a general phenomenon independent of the presence of the disease.

Chloroquine resistance in Plasmodium falciparum from Kenyan infants.

Forty-two infants, aged 6 to 24 months, infected with Plasmodium falciparum were identified in Kisumu, Kenya. Because of their age, all were presumably not semi-immune to malaria. Each infant was treated with 25 mg/kg chloroquine base and followed for 7 days. Forty-one infections were sensitive to chloroquine in vivo; asexual parasites disappeared in all by day 4 and were not present on days 5, 6, or 7. One infection was resistant in vivo; parasites disappeared by day 3 but recrudesced on day 4. Rieckmann micro in vitro tests for chloroquine were done on the 42 isolates. Interpretable results were found in 25. In vitro resistance was demonstrated in 18 (72%) isolates, including the patient with in vivo resistance; greater than or equal to 99% inhibition of schizont development only occurred in wells containing greater than or equal to 8 pmol chloroquine base (compared with less than or equal to 5.7 pmol/well for known sensitive isolates). This is the first demonstration of in vivo and in vitro chloroquine-resistant P. falciparum in a Kenyan. Comparison of these results with results from other studies carried out in the same area on the same area on older individuals suggests that the immune response may be playing a role in modifying the expression of resistance.

Control of schistosome-transmitting snails in Kenya by the North American crayfish Procambarus clarkii.

Snail-transmitted trematode parasites such as schistosomes and liver flukes assume considerable medical and veterinary significance in tropical Africa. We have observed a strong negative association between the presence of medically important pulmonate snails and the crayfish Procambarus clarkii in freshwater habitats in Kenya. This crayfish, introduced into Kenya around 1970, readily consumes these snails in the laboratory. Field enclosure experiments indicate that crayfish exert a significant negative impact on the abundance of Biomphalaria pfeifferi, the intermediate host of the human blood fluke Schistosoma mansoni. It is likely that P. clarkii will continue to spread naturally in Kenya and that schistosome-transmitting snails will be excluded or reduced in numbers where crayfish are present. Procambarus clarkii may represent an alternative, biological means of snail control in East Africa.

In vitro susceptibility of Plasmodium falciparum isolates from Jilore, Kenya, to antimalarial drugs.

Twenty-six Plasmodium falciparum isolates obtained during a prophylaxis study at Jilore primary school, Malindi, Kenya, were adapted to in vitro culture and their susceptibility to 13 antimalarial drugs was tested by a modified radioisotopic method. Pyrimethamine, chloroquine, amodiaquine, cycloguanil, chlorcycloguanil, quinine, quinidine and sulfadoxine, and the experimental compounds MB 35769, mefloquine, WR 184806, parvoquone, and menoctone were used. The isolates could be divided into two groups with significantly different susceptibility to pyrimethamine, shown by a 755-fold difference in the mean ID50 values (2.77 +/- 1.98 x 10(-10) mol/l and 2.09 +/- 1.64 x 10(-7) mol/l). The mean susceptibility of the two groups differed 7.7-fold for chlorcycloguanil and 14.6-fold for cycloguanil, but were not significantly different for the other drugs. All isolates were more sensitive to amodiaquine than to chloroquine in vitro. The ratio of the geometric mean ID50 values of chloroquine to amodiaquine was 3.13. The ratio for the chemically related compounds parvoquone to menoctone was 5.63, quinine to quinidine was 5.58, and mefloquine to WR 184806 was 12.16.

Predisposition to urinary tract epithelial metaplasia in Schistosoma haematobium infection.

Although there is strong epidemiologic evidence linking Schistosoma haematobium infection with carcinoma of the bladder, the utility of cytologic screening for urinary tract cancer has not been critically evaluated in S. haematobium-endemic populations. The present cross-sectional study examined urine cytology findings among 1,014 residents (ages 1 to 91) of the S. haematobium-endemic Msambweni area of Coast Province, Kenya. Among 705 evaluable cytology specimens, prevalence of inflammation (39%), hyperkeratosis (30%), metaplasia (33%), and frank atypia (0.4%) was notably higher than in previously studied, non-endemic populations. Overall, S. haematobium infection was strongly associated with increased risk for cytologic abnormality (> 2.8-fold relative risk of metaplasia or hyperkeratosis; P < 0.001). Age-group analysis confirmed parallel increases in metaplasia and S. haematobium infection prevalence early in life (from age I to 15 for both boys and girls). However, above age 20, metaplasia prevalence persisted at 33-45% prevalence despite a decline in infection prevalence and intensity. Prevalence of advanced (moderate or severe) metaplasia showed two age-related peaks: the first at 10-14 years of age (at the time of peak infection), and the second among subjects > or = 60 years old. No cancers were detected in the study population either on cytology or on follow-up ultrasound examination. These data suggest an age-dependent progression of cellular abnormalities in the urinary epithelium that is associated with chronic S. haematobium infection, which becomes independent of concurrent infection intensity as subjects grow older. Implications for cancer screening are discussed.

Concurrent infection with Leishmania donovani and Leishmania major in a Kenyan patient: clinical description and parasite characterization.

Leishmania isolates aspirated a few months apart from the spleen of an indigenous adult male kala-azar patient from Baringo District, Kenya, were biochemically characterized and compared. The patient lived within a dual focus of L. donovani kalazar and L. major cutaneous leishmaniasis. A primary Leishmania isolate from splenic aspirates was cryopreserved (NLB-294). The patient was treated with sodium stibogluconate for kala-azar and discharged. Three months later, he had clinical relapse and returned for retreatment. During his second visit, the patient participated in a diagnostic study in which urine and nasopharyngeal samples were cultured for leishmaniasis. Urine, nasopharyngeal, and splenic samples were positive for Leishmania. Secondary isolates from splenic (NLB-294-I) and urine (NLB-318) cultures were cryopreserved and characterized by cellulose acetate electrophoresis (CAE) using 20 enzymes. Whereas the urine isolate was typed as L. donovani, the splenic aspirate culture revealed a mixed infection with L. donovani and L. major. The primary isolate (NLB-294) was then characterized and also showed a mixed infection. To exclude the possibility of protein post-translational modifications in electrophoretic assays, the primary and secondary isolates were grown and processed under identical cultural and lysis conditions, and compared using CAE. The results were identical to the first electrophoretic assays showing mixed promastigote banding patterns. Stationary-phase promastigotes of the secondary splenic isolate (NLB-294-I) inoculated subcutaneously, intraperitoneally, and intracardially into Syrian hamsters and BALB/c mice produced both kala-azar and cutaneous leishmaniasis within 6.5 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of borehole wells on water utilization in Schistosoma haematobium endemic communities in Coast Province, Kenya.

To determine the impact of the introduction of borehole wells on water use patterns and the consequent risk of transmission of Schistosoma haematobium in 3 endemic villages in Kenya, we performed a survey (a 1:6 sample of affected households) to identify sources of water and types of water utilization before and after well introduction. Water usage was also determined in 2 unaffected neighboring villages not given borehole wells, but having continuous access to piped water from communal taps. Prior to borehole well construction, significantly more high-risk water use occurred in the borehole villages vs. comparison villages in terms of water gathered for cooking, drinking, dish washing, and bathing; residents of both types of villages preferred high-risk sources (marshes and ponds) for clothes washing. Following well introduction, there were significant declines in the use of high-risk water for drinking, cooking, and dish washing, but not for bathing or clothes washing. A higher proportion of individuals from the 3 borehole villages reported some type of continued contact with high-risk water sources. Despite well introduction and a 3 year chemotherapy program among school-aged children, a 21-28% incidence of infection persisted among children in the villages, suggesting minimal impact on transmission. Regular monitoring for S. haematobium infected snail sites showed no decline in the number or proportion of infected snails. Borehole well introduction can significantly alter some forms of water usage, but social and water quality factors may limit the ability of communal wells to reduce S. haematobium transmission.

Biochemical characterization and zymodeme classification of Leishmania isolates from patients, vectors, and reservoir hosts in Kenya.

A total of 407 Leishmania and other Leishmania-like isolates obtained from patients, other vertebrates, sand fly vectors, and other arthropods from Kenya and other countries were characterized and compared with several World Health Organization and other well-characterized reference strains of Leishmania, Trypanosoma, Crithidia, Herpetomonas, and Leptomonas by cellulose acetate electrophoresis (CAE), using 20 enzyme systems. Analysis of the isoenzyme banding patterns (IBP) of the isolates generated isoenzyme profiles that were resolved as zymodemes and tabulated. Isolates that produced similar isoenzyme profiles in all 20 enzyme systems were placed into a particular Leishmania isoenzyme taxon, with the zymodeme designated numerically as Zn. A total of 66 zymodemes were recorded for the 407 isolates studied. To obviate the need to draw all 66 representative IBP for each of the 20 enzyme systems, the 66 zymodemes (Z1-Z66) were again placed into similarity groups represented by pattern number or Pn. This resulted in 23-50 IBP (Pn) per enzyme system. The highest number of IBP scored was for malate dehydrogenase (MDH) (P1-50) and the lowest score was for glucose-6-phosphate isomerase (GPI) (P1-23). From these different isoenzyme profiles or zymodemes, IBP of 14 (MDH, GPI, nucleoside hydrolase, phosphoglucomutase, malic enzyme, isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, mannose-6-phosphate isomerase, 6-phosphogluconate dehydrogenase, glutamate oxaloacetate transferase/aspartate aminotransferase, glutathione reductase, superoxide dismutase, fumarase, and glyceraldehyde-3-phosphate dehydrogenase) of the 20 enzyme systems were selected for computer-calculated numerical taxonomy. Consistent individual isoenzyme bands with similar relative mobilities of the 14 enzyme systems were scored into groups (allelomorphs, allozymes, or electromorphs) and used in cluster analysis. For each pattern in every profile, the presence of a consistent band was entered as 1 and its absence as 0. A total of 419 allozyme characters (variables) were scored for the 14 enzyme systems. Lastly, all different zymodemes sharing a particular IBP (Pn) within an enzyme system were counted and the total number was shown as a zymodeme frequency (Zf). Final analysis of the CAE isoenzyme profiles and cluster-dendrograms resulted in the identification of several potentially new species and subspecies of Leishmania and other Leishmania-like isolates from patients, sand flies, and animal reservoir hosts collected from Kenya and other locations in Africa. Zymodeme analysis of the Kenyan visceral and cutaneous leishmaniasis isolates resulted in the identification of 11 subpopulations of the L. donovani species complex and six subpopulations of the L. tropica species complex endemic to different geographic areas of Kenya.

Leishmania donovani parasites in the nasal secretions, tonsillopharyngeal mucosa, and urine centrifugates of visceral leishmaniasis patients in Kenya.

In the early 1930s, investigators of visceral leishmaniasis stated that Leishman-Donovan bodies are found in body fluids of kala-azar patients, for example, in urine, feces, semen, and nasal and pharyngeal secretions. Based on this finding, we investigated the diagnostic potential of nasal secretions, tonsillopharyngeal mucosal swabs, and urine centrifugates inoculated into Schneider's Drosophila Medium (containing antibiotics and antifungal agents) as well as with Giemsa-stained smears. Consequently, 64 randomly selected patients with visceral leishmaniasis from Kenya (59 who were splenic culture or Giemsa stain positive and five who were culture negative but Giemsa stain positive) were tested by three noninvasive methods. These tests were all performed before the patients were treated with Pentostam. Cultures of nasal and tonsillopharyngeal swabs and urine centrifugates produced 28 positive samples representing 24 patients (37.5%). Moreover, a set of 25 Giemsa-stained slide smears made from the nasal and tonsillopharyngeal mucosa of 25 patients with visceral leishmaniasis who had not tested positive in cultures produced nine positives. Therefore, the overall total of patients who tested positive by all of the above methods was 33 or 51.6%. The cryopreserved Leishmania isolates were characterized by cellulose acetate electrophoresis using 20 enzyme systems. The isoenzyme profiles produced by the parasites were represented in five different L. donovani s.l. zymodemes. Representatives of these isolates were also characterized by DNA Southern blotting analysis, which corroborated the isoenzyme results.

Dose-finding study for praziquantel therapy of Schistosoma haematobium in Coast Province, Kenya.

To assess the efficacy of low dose praziquantel regimens in comparison with standard 40 mg/kg dosing in the treatment of urinary schistosomiasis, a random allocation dose-finding trial was performed in children and adults from a Schistosoma haematobium endemic region in Coast Province, Kenya. Following an initial screening, 280 individuals with greater than or equal to 50 eggs/10 ml urine were randomly assigned to receive either 10, 20, 30, or 40 mg/kg of the drug in a single oral dose. Two to three months later, cure rates of 26%, 68%, 78%, and 84% were found for the 10, 20, 30, and 40 mg/kg doses, respectively. The results of 10 mg/kg oral dosing were significantly worse than for all other doses in terms of cure rate and of post-treatment prevalence of morbidity. The 40 mg/kg dosing resulted in a significantly higher cure rate than the 20 mg/kg doses; nevertheless, there was no significant difference between 20 mg/kg and 40 mg/kg doses in terms of mean post-treatment intensity of infection or post-treatment prevalence of hematuria or proteinuria. For large-scale control programs, oral 20 mg/kg praziquantel therapy for urinary schistosomiasis may prove as effective as the standard oral 40 mg/kg dosing for control of infection-associated morbidity and reduction of parasite transmission.

Identification of snails infected with schistosomes by ELISA employing monoclonal antibodies: Schistosoma mansoni in laboratory snails (Biomphalaria glabrata) and in field snails (Biomphalaria pfeifferi) from Kenya.

An enzyme-linked immunosorbent assay (ELISA) employing monoclonal antibodies was used for detecting Schistosoma mansoni antigens in hemolymph of laboratory snails (Biomphalaria glabrata) in Kenya. Infected laboratory snails shedding cercariae were differentially identified by ELISA from uninfected snails with 100% sensitivity and specificity. Prepatent infections were detected by ELISA from 2 weeks after exposure to miracidia. Thus, ELISA revealed infection 3 weeks before maximal patency was reached (5-6 weeks post-exposure). Infected field snails (B. pfeifferi) shedding cercariae were differentially identified by ELISA, with 100% sensitivity and specificity, from uninfected field snails and from snails naturally infected with other trematodes (echinostomes and strigeids). Prepatent infections with S. mansoni were readily identified by ELISA in field snails. A case is demonstrated where infection rate, as determined by shedding test alone, was 9.8%, whereas the combined figure of prepatent and patent infection rates was 22.9%

Development of Leishmania major in Phlebotomus duboscqi and Sergentomyia schwetzi (Diptera: Psychodidae).

The extrinsic development of Leishmania major was observed in 2 man-biting sand flies, Phlebotomus duboscqi, a known vector, and Sergentomyia schwetzi, an assumed non-vector. Flies fed on a leishmanial lesion on the nose of a hamster were examined for infection at 0, 6, 12, 18, 24, 36, 48, and 60 hr and at approximately 24 hr intervals from day 3 to day 14 post-feeding. Infection rates, determined by light microscopy, were 47% (n = 258) in P. duboscqi and 5% (n = 162) in S. schwetzi. Transformation from amastigotes to "procyclic" promastigotes occurred in both species at 6-18 hr post-feeding. In P. duboscqi, the parasites multiplied rapidly and developed through as many as 10 forms, including at least 3 dividing-promastigote forms. Metacyclic promastigotes, the "infective" form, appeared at 6 days post-feeding, first in the region of the stomodeal valve, then in the pharynx, cibarium, and proboscis. In a single attempt 14 days post-feeding, a P. duboscqi transmitted L. major to a mouse by bite. In contrast, the parasites multiplied slowly in S. schwetzi, and did not develop beyond "procyclic" promastigotes. The parasites did not migrate anteriorly nor survive beyond 90 hr post-feeding, indicating that S. schwetzi is not a vector of L. major. Classical strategies for vector incrimination may be confounded by the isolation of non-infective early developmental forms of Leishmania from wild-caught non-vectors.

Visceral leishmaniasis unresponsive to pentostam caused by Leishmania tropica in Kenya.

We report the characterization of 6 Leishmania tropica isolates from 2 patients with visceral leishmaniasis who were unresponsive to treatment with sodium stibogluconate. The Leishmania isolates, MHOM/KE/81/NLB-029A, -029XIB, and -029XIC and MHOM/KE/81/NLB-030I, -030B, and -030XXA, all from splenic aspirates, were characterized by cellulose acetate electrophoresis using 11 enzymes: malate dehydrogenase, malic enzyme, phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, superoxide dismutase, glutamate-oxaloacetate transaminase, adenylate kinase, nucleoside hydrolase, mannose phosphate isomerase, glucose phosphate isomerase, and phosphoglucomutase. Isozyme migration patterns were indistinguishable from those of 2 WHO reference strains of Leishmania tropica (MHOM/SU/60/LRC-L39, NLB-305 and MHOM/IQ/OO/LRC-L36, NLB-067). These are the first reported cases of visceral leishmaniasis (kala-azar) caused by L. tropica in Africa; these cases were refractory to sodium stibogluconate.