Age related efficiency of the leishmanin skin test as a marker of immunity to human visceral leishmaniasis.

This study aimed at investigating whether the efficiency of the leishmanin skin test (LST) to evaluate the immune status of individuals exposed to Leishmania (L.) infantum is age-related. It was conducted in two districts of the governorate of Kairouan, an endemic region for L. infantum infection in Tunisia. Healthy individuals (n = 119) were selected according to two criteria: no current or past history of visceral or cutaneous leishmaniasis, and their age range: 1-6 years (group I), 7-14 years (group II), and 20-66 years old (group III). Assessments comprised LSTs, in vitro lymphoproliferative response, and interferon-gamma (IFN-gamma) productions induced by soluble leishmanial antigens (SLA). LST recorded an overall of 89.07% and 89.9% concordance with T cell proliferation and IFN-gamma production induced by SLA, respectively. Using in vitro tests as gold standards, LST was found more sensitive for screening individuals from group I (96% and 100%, considering T cell proliferation and IFN-gamma production results, respectively), than group II (91% and 97%) and group III (70% and 74%,). Conversely, LST was less specific in group I (84% and 77%) than group II (100% and 94%) and group III (100% for both in vitro tests). Our results suggested that the strength of LST resided in its higher sensitivity, to unravel asymptomatic injections and cell mediated immunity to L. infantum parasite in infants and its higher specificity for screening adult individuals. Negative LST in adults and positive LST in children < 5 years, the population at risk of developing visceral leishmaniasis, remain the weaknesses of LST and should be interpreted with caution.

Dogs L. infantum infection from an endemic region of the north of Tunisia: a prospective study.

A follow-up study of 917 dogs was undertaken between 1994 and 1995 in the focus of visceral leishmaniasis in northern Tunisia. It permitted to assess the demography of the dog population, the importance of canine leishmaniasis (CL) and the determinants of seropositivity and mortality of dogs. Canine population was stable through time with an input of 231 dogs and an output of 218 dogs per year. The prevalence of seropositivity was 18% and 22.3% in 1994 and 1995 respectively and 90% of dogs were asymptomatic. Among 525 negative dogs in 1994 and reassessed in 1995, 78 seroconverted revealing an annual cumulative incidence of 14.74%. On the other hand, 23.47% (27/115) of seropositive dogs became negative in 1995. Age, presence of symptoms and density of dogs were independently associated with CL seropositivity. These results demonstrate the difficulty of control strategies of visceral leishmaniasis targeting the dog population.

Validation of a modified commercial assay for the detection of rubella-specific IgG in oral fluid for use in population studies.

Matching serum and oral fluid (saliva) samples were collected from 369 subjects in Tunisia in 2002, from a city in the north and a rural district in the south. Rubella-specific IgG was detected in sera by commercial ELISA (Dade Behring) and in matching oral fluids by two methods, a previously described IgG-capture ELISA (GACELISA) [J. Clin. Microbiol. 37 (1999) 391] and the Dade Behring ELISA with the assay protocol modified for use with oral fluids. Total IgG concentration of oral fluids was also measured. Rubella-specific IgG was detected in 289 (78.3%) sera overall. Differences in the age distribution of the study population in the north and south led to a higher prevalence being found in the north (86.2%) than in the south (71.8%). This difference was reflected in the oral fluid rubella-specific IgG results. With GACELISA, rubella-specific IgG was detected in 79.4% of oral fluids from the north and 69.7% from the south and with the modified Dade Behring assay, in 81.4% of oral fluids from the north and in 64.9% from the south. The sensitivity and specificity of GACELISA in comparison to results from the matching sera were 92.4 and 93.2%, respectively. The sensitivity and specificity of the modified Dade Behring ELISA were 89.8 and 92.0%, respectively. Total IgG concentration in oral fluid showed a weak correlation (r=0.19) with the modified Dade Behring results and with samples where total IgG was >7.5 mg/l, the sensitivity and specificity were 94.4 and 90.0%, respectively. Twenty-nine oral fluids, which gave false negative rubella-specific IgG results with the modified Dade Behring ELISA, had a lower mean total IgG concentration than 256 oral fluids which gave concordant positive results (7.0mg/l versus 15.8 mg/l, P<0.001). The study validated the modified Dade Behring ELISA, providing an alternative to the GACELISA for assessing levels of rubella immunity for population studies using oral fluid samples.

[Risk factors of leishmanin-skin test positivity in transmission of Leishmania infantum in the center of Tunisia]. / Les déterminants de la positivité au test cutané à la leishmanine dans l'aire de transmission de Leishmania infantum dans le centre tunisien.

This work aims to estimate prevalence and evaluate risk factors of leishmanin-skin test positivity. A cross-sectional leishmanin skin test study was carried out on a sample of 3190 healthy volunteers living in the gouvernorates of Kairouan and Kasserine. Age standardized prevalence of leishmanin-skin test positivity was 45.9% (CI95% = [43.9-47.9]) confirming the hyper endemicity of this region. The rate of leishmanin-skin test positivity ranged from 75.9% (CI95% = [71.9-79.5]) in Zaghdoud (Kairouan) to 6.5% (CI95% = [3.7-11.01) in Abdeladhim (Kasserine). There is no significant difference between men and women suggesting a similar exposure to infection. In the districts of Zaghdoud, Sidi Amor, El Hajeb and chbika, age specific rates showed a rapid increasing positive prevalence with age reaching a proportion exceeding 80% after the age of 15 years. However, the age specific prevalence from other delegations showed a progressive increasing trend with age, with a low rate for younger children and a plateau of 75% after 45 years. Multivariate analysis of leishmanin-skin test positivity risk factors showed that only district and age are determinants of this infection.

[Concordance of leishmaniasis cutaneous tests in Tunisia]. / Concordance des tests cutanés à la leishmanine en Tunisie.

A cross sectional study aimed to evaluate the effect of antigenic preparation (Leishmania infantum versus Leishmania major) and dose of leishmania antigens (5 x 10(6) versus 2.5 x 10(6) parasites in the same volume) on the reproducibility of delayed type hypersensitivity leishmania skin test. Results showed that among 34 individuals involved from visceral leishmaniasis endemic area. 26 (76.5%) had a positif Leishmania infantum leishmania (L-L. infantum) test and 27 (79.4%) to Leishmania major leishmania (L-L. major). Mean size of cutaneous reaction was 5.94 +/- 2.86 mm for L-L. infantum and 5.41 +/- 3.23 mm for L-L. major, with a significant positive linear association (p < 10-3). Intra-class correlation coefficient was 0.80 (CI95% = [0.64-0.93]) and concordance Kappa (kappa) was 0.57 (CI95% = [0.40-0.74]). Among 153 individuals from zoonotic cutaneous leishmaniasis. 92.9% revealed a positive test for both types of leishmanin (L-L. major full dose versus L-L. major half dose). Mean size of cutaneous reaction was 12.61 +/- 4.65 mm for the reference test and 11.30 +/- 3.95 mm for diluted one, with a positive linear association (p < 10-3). Intra-class correlation coefficient was 0.78 (IC95% = [0.71-0.84]) and concordance Kappa (kappa) was 0.82 (IC95% = [0.73-0.91]). These results demonstrate a limited effect of leishmania antigenic variation and antigen dose on the reproducibility of delayed type hypersensitivity induced by the leishmanin test.

[Efficacy of intra-lesional glucantime in the treatment of zoonotic cutaneous leishmaniasis in basic health care conditions]. / Efficacité du traitement de la leishmaniose cutanée zoonotique par le glucantime en intra-lésionnel, dans les conditions des soins de santé de base.

A randomized placebo-controlled trial treating cutaneous lesions due to Leishmania major with intralesionnel glucantime, was conducted in El Guettar between december 1994 and June 1995, in order to assess efficacy of this therapy under field conditions. It included 109 patients: 52 were administrated glucantime and 57 received local treatment (eosin 5% and alcohol 95%). Prognostic factors were similar in both groups. Results did not reveal a significant difference between glucantime and eosin regarding the rapidity of the healing of lesions. However, scars seem to be of better quality among the glucantime group. Bacterial super infection was noticed among 57.6% of humid lesions sampled among 33 patients. Isolated strains included group A streptococcus (22%), staphylococcus aureus (16.7%) or an association of both agents (61.1%). Resistance profile indicated that streptococcus and staphylococcus respond well to macrolids compared to other antibiotic groups.

A randomized, placebo-controlled trial in Tunisia treating cutaneous leishmaniasis with paromomycin ointment.

A randomized, placebo-controlled, double-blind trial was carried out in 1992 in central Tunisia to assess the tolerability and efficacy of paromomycin ointment against zoonotic cutaneous leishmaniasis caused by Leishmania major. One hundred fifteen patients, 2--60 years of age, with a single lesion of parasitologically confirmed cutaneous leishmaniasis, were included in the trial. The ointment was applied twice a day from day 1 through day 14. Clinical and parasitologic evaluations of lesions were done at days 0, 15, 45, and 105. Fifty-seven patients were allocated the treatment and 58 the placebo. Based on local toxicity and laboratory evaluation, there was no difference in tolerability between the two groups. Parasitologic evaluation at day 15 showed that 74.5% of the treated group had negative smears compared with 56.4% among controls (P = 0.06). This difference was no longer apparent at days 45 and 105. Clinical evaluation at days 15, 45, and 105 did not indicate any difference between the two groups. The clinical evaluation at day 15 was a good predictor of the final prognosis of the lesion in the two groups when analyzed separately, suggesting no clinical relapse in either group. These findings suggest that paromomycin ointment should not be used in the present formulation as a treatment for zoonotic cutaneous leishmaniasis in Tunisia.

[Spontaneous course of lesions of Leishmania major cutaneous leishmaniasis in Tunisia]. / Evolution spontanée des lésions de leishmaniose cutanée a Leishmania major en Tunisie.

INTRODUCTION: The evolution of zoonotic cutaneous leishmaniasis (ZCL) caused by L. major, was usually described with crosssectional studies of patients under anti-leishmanial drugs. This work aimed to describe the clinical and parasitological status by a follow-up study of patients with ZCL and treated with a placebo. MATERIAL AND METHODS: In 1992, 58 patients with unique lesion of ZCL confirmed parasitologically and treated with vaseline twice a day for 15 days were followed in days 0, 15, 45 and 105. During every visit we have performed a clinical description of the lesion, a direct smear and a culture on NNN medium. RESULTS: 81 p. 100 of the lesions were ulcerated in day 0. A rapid clinical healing was noticed in 6.9 p. 100 of patients and the lesion remained active in 25.9 p. 100 of cases until day 105. Direct smears became negative among 56.4 p. 71 p. 100 and 92.3 p. 100 in days 15, 45 and 105 respectively. DISCUSSION: The ulcer was the most frequent sign during the diagnosis. The rapid conversion of positive parasitological tests suggest that the diagnosis of ZCL in endemic zones should be based mainly on clinical criteria.