Double-blind placebo-controlled study of concurrent administration of albendazole and praziquantel in schoolchildren with schistosomiasis and geohelminths.

A double-blind placebo-controlled study of the concurrent administration of albendazole and praziquantel was conducted in>1500 children with high prevalences of geohelminths and schistosomiasis. The study sites were in China and the Philippines, including 2 strains of Schistosoma japonicum, and 2 different regions of Kenya, 1 each with endemic Schistosoma mansoni or Schistosoma haematobium. Neither medication affected the cure rate of the other. There was no difference between the side effect rate from albendazole or the double placebo. Praziquantel-treated children had more nausea, abdominal pain, and headache but these side effects were statistically more common in children with schistosomiasis, suggesting a strong influence of dying parasites. The subjects were followed for 6 months for changes in infection status, growth parameters, hemoglobin, and schistosomiasis morbidity. In all 4 sites, a significant 6-month increase in serum hemoglobin was observed in children who received praziquantel, strongly supporting population-based mass treatment.

Bacteriuria in a cohort of predominantly HIV-1 seropositive female commercial sex workers in Nairobi, Kenya.

Although significant bacteriuria and urinary tract infection are more common in immunocompetent women than men, studies linking HIV immunosuppression with an increased risk of developing urinary infection have so far only been carried out in men. We therefore examined the relationship between bacteriuria and HIV status and CD4+cell count in a relatively homogeneous cohort of female commercial sex workers (CSW) attending a community clinic in Nairobi. Two hundred and twenty-two women were enrolled, and grouped according to HIV status and CD4 count. Group 1 were HIV seronegative (n = 52); Group 2 were HIV seropositive with CD4 + counts above 500 x 10(6)/l (n = 51); Group 3 were HIV seropositive with CD4 + counts between 201 and 500 x 10(6)/l (n = 67); Group 4 were HIV seropositive with CD4+counts below 200 x 10(6)/l (n = 52). Clinical signs and symptoms were noted and mid-stream specimens of urine obtained for culture and sensitivity. Overall 23% (50/222) had significant bacteriuria. The rates in each group respectively were 25%, 29%, 19% and 23% and there was no significant association between bacteriuria and HIV status; or between bacteriuria and level of immuno-suppression as indicated by CD4 + count. Overall 19% (30/222) of women had symptoms (frequency; dysuria; loin pain; smelly urine) or signs (fever; loin tenderness) compatible with urinary tract infection. However there was no significant association between symptoms or signs of infection and bacteriuria or HIV status. A typical range of pathogens, predominantly Enterobacteriaceae, were isolated and there were high rates of resistance to commonly used antimicrobials as well as 10% resistance to ciprofloxacin. Although high rates of significant bacteriuria can occur in highly sexually-active women, this appears unrelated to HIV infection or the level of HIV-related immunosuppression and is generally asymptomatic or clinically indistinct.

Acute phase protein concentrations predict parasite clearance rate during therapy for visceral leishmaniasis.

Visceral leishmaniasis (VL) remains a major health problem in Kenya and other parts of Africa, Central America and Asia. Currently, splenic aspirate smear and culture are the standard methods of monitoring therapy and relapse. Acute phase reactant markers, C-reactive protein (CRP), serum amyloid A protein (SAA) and alpha 1-acid glycoprotein (AGP) were evaluated as less invasive techniques for monitoring therapy in 59 patients with VL before, during and after therapy. CRP, SAA and AGP were elevated in VL patients at admission and the concentrations decreased with effective therapy to reach normal levels by the end of therapy (SAA and AGP) or by 3 months follow-up (CRP). Two groups of patients were selected on the basis of rate of parasite clearance. The acute phase protein concentrations were significantly raised in those slower to clear parasites. Analysis of sensitivity and specificity of acute phase proteins as predictors of parasite clearance suggested that they might represent useful non-invasive markers for monitoring disease activity, response to therapy and relapse in VL.

A prospective sero-epidemiological study of visceral leishmaniasis in Baringo District, Rift Valley Province, Kenya.

The incidence of visceral leishmaniasis (VL) was studied in 30 clusters with an average of 98 individuals in each cluster in a defined, endemic rural area of Baringo District, Kenya. The clusters were centred around recent cases of VL. Anti-leishmanial antibodies were measured by the direct agglutination test (DAT) and a clinical examination was performed on 2 occasions between April 1991 and May 1993. Of 2934 individuals tested by the DAT during the first visit, 78 (2.7%) were seropositive, 54 with and 24 without a history of VL. The seroconversion rate was 9/1000 person-years of observation (95% confidence interval 5.1-12.92) among 2332 seronegative individuals retested the following year. During the entire study period, VL was diagnosed in 10 patients, with an incidence rate of 2.2/1000 person-years of observation (95% confidence interval 0.8-3.6). Household contacts of individuals with previously confirmed VL had a higher frequency of DAT positivity than the rest of the population. This difference was significant for both sexes. These results suggest transmission in and around houses.

Visceral leishmaniasis: use of the polymerase chain reaction in an epidemiological study in Baringo District, Kenya.

The polymerase chain reaction was applied to capillary blood spots dried on filter paper from 20 parasitologically proved cases of visceral leishmaniasis (VL), 21 subclinical cases, and 11 healthy controls in a longitudinal study of anthroponotic VL in Baringo District, Kenya. Leishmania deoxyribonucleic acid (DNA) was detected 10.5 months before diagnosis and up to 3 years after diagnosis and apparently successful treatment. Subclinical cases can have detectable circulating parasite DNA in their blood. These findings may indicate that subclinical cases can be a reservoir and formerly treated VL patients can remain a reservoir for a long time. Xenodiagnosis should be performed on subclinical cases and former VL patients to establish their role in transmission of VL in Kenya.

Interferon-gamma and interleukin-4 production by human T cells recognizing Leishmania donovani antigens separated by SDS-PAGE.

Crude preparations of Leishmania donovani proteins were separated by preparative SDS-polyacrylamide gel electrophoresis. Fractions of separated proteins were recovered by electroelution directly from the gel into separate chambers. The isolated protein fractions were tested for induction of proliferation and interferon-gamma (IFN-gamma) production in cultures of peripheral blood mononuclear cells (PBMC) from individuals who had recovered from visceral leishmaniasis caused by L. donovani. The release of interleukin-4 (IL-4) by PBMC stimulated with the isolated L. donovani antigen fractions was measured after treatment with phorbol-myristate-acetate and ionomycin. The cells proliferated in response to all protein fractions with molecular weights in the range < 12 kDa to 85 kDa. In general, IFN-gamma was secreted in response to stimulation with all the protein fractions, whereas IL-4 production was infrequently observed. The results show that T cells from individuals who have been cured of visceral leishmaniasis recognize and respond to a wide range of leishmanial antigens. There was no evidence of particular fractions constantly giving either IFN-gamma or IL-4-producing responses.

Splenomegaly in Baringo District, Kenya, an area endemic for visceral leishmaniasis and malaria.

The relationship between splenomegaly and visceral leishmaniasis (VL) was investigated during a cross-sectional study in 2,941 individuals in Baringo District, Kenya, where both malaria and VL are endemic. Spleen size was correlated with presence of malaria parasites in thick blood films and with evidence of present or past Leishmania donovani infection as determined by serology and history. Marked splenomegaly (Hackett grade 3 or greater) significantly correlated with present or previous leishmanial infection (chi 2 = 53.5; p < 0.001) whereas moderate splenomegaly (Hackett grade 1 or 2) significantly correlated with malaria parasitaemia (chi 2 = 73.03; p < 0.001). The presence of antimalarial antibodies did not contribute to the differentiation of the cause of splenomegaly. The diagnostic significance of splenomegaly in this population is discussed.

Phase 2 efficacy trial of an oral 8-aminoquinoline (WR6026) for treatment of visceral leishmaniasis.

The efficacy of an oral 8-aminoquinoline (8-[[6-(diethylamino)hexyl]amino]-6-methoxy-4-methylquinoline) (WR6026) in the treatment of 16 patients with kala azar was evaluated. The first 8 patients received therapy for 2 weeks at a dosage of 0.75-1.00 mg/(kg.d); 1 patient was cured, and in regard to the other 7, a 1-logarithm decrease in the number of splenic parasites and clinical improvement were noted. The next 8 patients received therapy for 4 weeks at the same daily dosage (1 mg/[kg.d]); 4 were cured, and for the other 4, 1- to 2-log decreases in the number of parasites and clinical improvement (in regard to weight, liver and spleen size, hemoglobin level, and leukocyte count) were noted. The therapy was associated with minimal toxicity; adverse effects included gastrointestinal distress, headache, and methemoglobinemia. The fact that one-half of the patients were cured indicates that future trials with longer regimens and higher dosages are warranted and should include patients for whom existing treatment methods have failed.

Conservation of the Plasmodium falciparum sporozoite surface protein gene, STARP, in field isolates and distinct species of Plasmodium.

The extent of structural conservation of the Plasmodium falciparum sporozoite surface protein gene, STARP, recently characterized in the T9/96 clone, has been analyzed using the polymerase chain reaction. Results from Ivory Coast and Thai clones, field isolates originating from Brazil and Kenya and laboratory-maintained strains strongly suggest that this gene has a highly conserved structure throughout this species. This structure includes a complex repetitive central domain consisting of a mosaic region followed by tandem 45-amino acid-encoding (Rp45) and 10-amino acid-encoding (Rp10) repeat regions. Limited size variation in this domain appeared to result from highly localized duplication events in the Rp45 and Rp10 regions. No size variation was observed in the 5' and 3' coding non-repetitive regions, but minor size polymorphism was found in the single intron at the 5' end of the gene. No evidence was found of distinct families of polymorphic types, as has been observed with the blood-stage MSA-1, MSA-2 and S-antigens. The sequence of the STARP homologue in the phylogenetically close chimpanzee parasite, Plasmodium reichenowi, has also been elucidated and reveals high sequence conservation, although interesting differences were detected in the composition of the Rp10 region, known in P. falciparum to contain B- and T-cell epitopes. Finally, DNA hybridization reveals the presence in rodent malaria species of sequences containing homology to the STARP non-repetitive (though not the repetitive) regions, which would suggest that a similar, conserved gene may exist in these species.

Relationship between direct agglutination test and splenic aspirate smear parasite load in visceral leishmaniasis at Baringo District, Kenya.

Direct agglutination test was carried out in Baringo District on 100 persons presenting with signs and symptoms suggestive of visceral leishmaniasis. Splenic aspirate smears and cultures were done on these 100 persons in order to parasitologically confirm the findings of the direct agglutination test. It was found that the direct agglutination test positively detected all 79 (79%) patients parasitologically confirmed to have visceral leishmaniasis. Irrespective of the splenic aspirate smear parasite rate, whether 1+ or 6+ on a logarithmic scale, direct agglutination test was positive. There were 21% false positives, two of whom had Schistosoma mansoni in their stools. It was not immediately known about the cause of the other false positives. It was concluded that the direct agglutination test is a good provisional serodiagnostic test for visceral leishmaniasis and should be considered for wider field application.

Is one year follow-up justified in kala-azar post-treatment?

Sixty-five patients, 51 males and 14 females, with clinical and parasitological evidence of visceral leishmaniasis were initially treated as follows: 44.6% were on intravenous sodium stibogluconate (pentostam) 20 mg/kg/d for 30 days, 35.4% was on a combination of pentostam as above and allopurinol 21 mg/kg/d in three divided doses for 30 days while 20% was on pentostam 10 mg/kg thrice/d intravenously for 10 days. All patients were parasitologically negative by the end of their respective treatment regimen. All patients were reviewed at 2 months, 6 months, and 12 months periods in order to evaluate the relapse rates and optimal follow-up period. Thirteen patients (20%) relapsed at 2 months and one patient (1.5%) relapsed at 6 months follow-up periods respectively. There was no relapse between 6 months and 12 months follow-up period. The mean liver and spleen sizes in responders showed a dramatic reduction at 2 months follow-up and thereafter a gradual reduction occurred in the next 10 months. Weight gain continued throughout the year. Apart from platelet count which showed a sustained high level from discharge to 12 months follow-up, the peripheral blood indices stabilized from 2 months follow-up. Relapses were retreated until parasitologically negative twice and then followed up, for a period of 12 months. At follow-up the liver and spleen sizes reduced gradually in the next 12 months.(ABSTRACT TRUNCATED AT 250 WORDS)

The efficacy and safety of ketoconazole in visceral leishmaniasis.

This study was an open evaluation of the efficacy and safety of Ketoconazole, 15 mg/kg/day orally for 3 weeks in 7 evaluable patients with Visceral Leishmaniasis in Kenya. Of all the seven patients who received ketoconazole, none had appreciable clearance of parasites from the splenic aspirate smears that were microscopically examined. All the splenic aspirate cultures done on these patients in the three weeks remained positive for leishmania parasites. Splenic sizes of these patients generally remained unchanged throughout the study period. The mean haemoglobin at the start of treatment was not different from that at the end of treatment. Liver function tests throughout treatment remained unchanged, i.e. within normal limits. It is concluded that Ketoconazole, 15 mg/kg/day orally given to these patients was not effective as an antileishmania drug although there was a one log drop in the parasite load. However, no serious side effect were noted in all of the patients during treatment.

The microfilarial periodic pattern of Wuchereria bancrofti in Kenya.

Microfilarial periodic pattern of Wuchereria bancrofti in Kenya was confirmed by the statistical method proposed by Aikat and Das (1977). Fifteen microfilarial positive individuals were brought to Nairobi from Malindi, which is one of the filariasis foci on the coastal area of Kenya. From each individual a 60-microliter finger prick blood film was made every 2 hours throughout one complete 24-hour cycle. The blood films were dried for at least 48 hours and dehaemoglobinized. The fluid was filtered using Nuclepore membrane to recover any detached microfilariae. The films were stained with Giemsa and microfilariae were counted. The peak time was 0056 h (4 minutes to 1 a.m.) and the periodicity index was 117.08, confirming the nocturnal periodicity.

Studies on the prevalence of leishmanin skin test positivity in the Baringo District, Rift Valley, Kenya.

The leishmanin skin test (LST) was applied in 26 clusters of an average of 97 individuals in Baringo District, Kenya. These clusters were centered around recent cases of visceral leishmaniasis (VL). Of 2,411 individuals tested, 254 (10.5%, 155 males and 99 females) had a positive reaction. Among cured VL patients, the frequency was approximately 30% and no sex difference was observed. In the population as a whole, LST positivity increased with age to a stable level from approximately 15 years of age, reflecting an endemic situation. The level of LST positivity was 25-30% and 10-15% in males and females, respectively. Uninfected household contacts of VL cases had a higher frequency of LST reactivity than the rest of the population. This relationship was significant only in females and children, the prevalence ratio being 2.3 (95% confidence interval 1.3-4.1), 1.9 (1.1-3.5), and 1.4 (0.8-2.5) for females, children, and males, respectively. The frequency of LST positivity was higher individuals living in wood houses than in individuals living in house with mud or stone walls. Again, this difference was significant only in females and children (P = 0.02 and P = 0.04), but not in males (P = 0.7). The results suggest that children and women are exposed to the parasite in or around their houses, whereas adult males are, in addition, exposed elsewhere.

Use of pharmacological agents to implicate a role for phosphoinositide hydrolysis products in malaria gamete formation.

The kinetics of phosphoinositol 4,5 bisphosphate hydrolysis products in activated Plasmodium falciparum gametocytes suggests a role for inositol trisphosphate [Ins(1,4,5)P3] and diacylglycerol (DAG) in the signal transduction pathway of malaria gametocytes. To investigate further this role, compounds that have an effect on the metabolism and biologic functions of these second messengers were tested in an in vitro system. Gentamycin, 2,3 diphosphoglycerate (2,3 DPG) and magnesium ion (Mg2+), inhibitors of Ins(1,4,5)P3 5' phosphatase, all stimulated gametocytes to exflagellate in suspended animation buffer, pH 7.4, at room temperature. In addition, methylxanthines, caffeine and theobromine, calcium ionophore (A-23187), and external calcium also stimulated exflagellation. In contrast, neomycin, an aminoglycoside that inhibits phospholipase C activity, and heparin, an antagonist of Ins(1,4,5)P3 binding to its receptor, inhibited microgamete formation. Quinine and chloroquine which can inhibit both phospholipase A and C activity also inhibited gametocyte exflagellation. The consistent manner in which these various compounds affect gametocyte activation further implicates phosphoinositol turnover in the signal transduction pathway of falciparum gametocytes.

Production of interferon-gamma and interleukin-4 by human T cells recognizing Leishmania lipophosphoglycan-associated protein.

The Leishmania protein LPGAP which is co-isolated with lipophosphoglycan is a specific activator of T cells from individuals who have recovered from American leishmaniasis. We have tested the effect of LPGAP on peripheral blood mononuclear cells (PBMC) from Kenyan donors cured from L. donovani infections. LPGAP induced vigorous proliferation and production of interferon-gamma (IFN-gamma) by the cells. In addition PBMC incubated with LPGAP released interleukin-4 (IL-4) after pulsing with ionomycin and phorbol myristate acetate. Single cells were isolated from LPGAP-stimulated cell lines and expanded as T-cell clones. LPGAP-reactive T-cell clones were activated by crude preparations of both promastigotes and axenic grown amastigote-like parasites. Among 9 CD4+ T-cell clones recognizing LPGAP, cells secreting predominantly IFN-gamma as well as cells secreting predominantly IL-4 were identified. The results show that both IFN-gamma producing (Th1-like) and IL-4 producing (Th2-like) T cells recognizing LPGAP are expanded after infection with L. donovani in humans.

A new focus of kala-azar due to Leishmania donovani sensu lato in Kenya.

Three Masai children from Kekonyokie South Location, Kajiado District were diagnosed with visceral leishmaniasis (kala-azar). Leishmanial isolates from the patients were characterized as Leishmania donovani sensu lato, by cellulose acetate electrophoresis. Case histories indicated that the disease was acquired locally. A survey of 409 children at 7 local primary schools and one nursery school revealed no additional case. Sandfly surveys using light traps and sticky paper traps recovered 10 species of sandfly, including 2 Phlebotomus species. P. martini was prevalent throughout the area. P. orientalis was only rarely encountered, but it was the first collection record of this species in the southern portion of the Rift Valley in Kenya. Although no Leishmania-infected sandfly was found, P. martini is probably the vector of kala-azar in the location, as it is elsewhere in Kenya.

A new rural focus of cutaneous leishmaniasis caused by Leishmania tropica in Kenya.

We have identified a new rural focus of cutaneous leishmaniasis caused by Leishmania tropica in Muruku sublocation, Salama location, Laikipia district, Rift Valley province, Kenya. Based on a few available case histories, previous reports of L. tropica in Kenya indicated a tentative geographical distribution. Recently 6 indigenous Kenyans from the new focus, who had never travelled outside Kenya, developed cutaneous lesions on the face and/or extremities found to contain Leishmania by culture and smear. Most of the patients manifested the typical 'urban' dry sore which grew slowly into a nodule measuring 2 x 1 cm to 9.5 x 3 cm, and after some months formed a central crust surrounded by small satellite papules. After treatment with Pentostam (sodium stibogluconate), about 40% of the sores failed to heal completely, either scarring centrally with fulminating papules at the edges and spreading peripherally, or healing but then recrudescing at the edge of the scar. Stationary-phase promastigotes from culture isolates were analysed by cellulose acetate electrophoresis. Isoenzyme profiles of 6 isolates were compared with those of World Health Organization reference strains using 12 enzyme loci; they were indistinguishable from those of 2 L. tropica reference strains. All 6 case sites lay within a radius of 4 km. Several other suspected cases from the same area are being investigated.

Immune responses after treatment for Schistosoma mansoni infections.

The changes in the immune responses of patients before and at 3 weeks after treatment with anti-schistosomal drugs were investigated. Lymphocyte responses to Concanavalin A and to worm antigens were inhibited after treatment, whereas responses to cercarial and egg antigens remained unchanged. Eosinophil levels were significantly elevated after treatment and were positively correlated with the increase in anti-worm antibodies (r = 0.587), and negatively associated with anti-egg antibodies (r = -0.727). Although the eosinophil-dependent cytotoxicity to schistosomula was not significantly enhanced after treatment, some increased killing was evident of half the patients (7/15). On the other hand, the ability of adherent mononuclear cells to stimulate eosinophil functions was markedly enhanced by treatment (P less than 0.001). These studies suggest that treatment may enhance some of the potentially protective host's immune mechanisms.

Post kala-azar dermal leishmaniasis: the Kenyan experience.

Post kala-azar dermal leishmaniasis (PKDL) occurs occasionally after successful cure of visceral leishmaniasis. Twelve patients with diagnosis consistent with PKDL were seen at Clinical Research Centre from 1981 to 1985. Clinical presentation ranged from macular hypopigmented lesion to generalized nodular lesions. All lesions cleared either by self-cure or by treatment with sodium stibogluconate.