Prevalence of malaria in an area receiving seasonal malaria chemoprevention in Niger.

BACKGROUND: Malaria transmission is highly seasonal in Niger. Despite the introduction of seasonal malaria chemoprevention (SMC) in the Magaria District, malaria incidence remains high, and the epidemiology of malaria in the community is not well-understood. METHODS: Four cross-sectional, household-based malaria prevalence surveys were performed in the Magaria District of Niger between October 2016 and February 2018. Two occurred during the peak malaria season and two during the low malaria season. Individuals in each of three age strata (3-59 months, 5-9 years, and 10 years and above) were sampled in randomly-selected households. Capillary blood was collected by fingerprick, thick and thin blood films were examined. Microscopy was performed at Epicentre, Maradi, Niger, with external quality control. The target sample size was 396 households during the high-season surveys and 266 households during the low-season surveys. RESULTS: Prevalence of parasitaemia was highest in children aged 5-9 years during all four surveys, ranging between 53.6% (95%CI 48.8-63.6) in February 2018 and 73.2% (66.2-79.2) in September 2017. Prevalence of parasitaemia among children aged 3-59 months ranged between 39.6% (33.2-46.4) in February 2018 and 51.9% (45.1-58.6) in October 2016. Parasite density was highest in children aged 3-59 months during all four surveys, and was higher in high season surveys than in low season surveys among all participants. The prevalence of gametocytaemia in children aged 3-59 months ranged between 9.9% (6.5-14.8) in February 2018 and 19.3% (14.6-25.2) in October 2016. The prevalence of gametocytaemia in children aged 5-9 years ranged between 6.3% (3.5-11.1) in February 2018 and 18.5% (12.7-26.1) in October 2016. CONCLUSIONS: Asymptomatic malaria infection is highly prevalent in this area, even during the season with low incidence of clinical malaria. The high prevalence of parasitaemia in children aged 5-9 years warrants considering their inclusion in SMC programmes in this context.

Clinical diagnostic evaluation of HRP2 and pLDH-based rapid diagnostic tests for malaria in an area receiving seasonal malaria chemoprevention in Niger.

BACKGROUND: Rapid diagnostic tests (RDT) for malaria are common, but their performance varies. Tests using histidine-rich protein 2 (HRP2) antigen are most common, and many have high sensitivity. HRP2 tests can remain positive for weeks after treatment, limiting their specificity and usefulness in high-transmission settings. Tests using Plasmodium lactate dehydrogenase (pLDH) have been less widely used but have higher specificity, mostly due to a much shorter time to become negative. METHODS: A prospective, health centre-based, diagnostic evaluation of two malaria RDTs was performed in rural Niger during the high malaria transmission season (3-28 October, 2017) and during the low transmission season (28 January-31 March, 2018). All children under 5 years of age presenting with fever (axillary temperature > 37.5 °C) or history of fever in the previous 24 h were eligible. Capillary blood was collected by finger prick. The SD Bioline HRP2 (catalog: 05FK50) and the CareStart pLDH(pan) (catalog: RMNM-02571) were performed in parallel, and thick and thin smears were prepared. Microscopy was performed at Epicentre, Maradi, Niger, with external quality control. The target sample size was 279 children with microscopy-confirmed malaria during each transmission season. RESULTS: In the high season, the sensitivity of both tests was estimated at > 99%, but the specificity of both tests was lower: 58.0% (95% CI 52.1-63.8) for the pLDH test and 57.4% (95% CI 51.5-63.1) for the HRP2 test. The positive predictive value was 66.3% (95% CI 61.1-71.2) for both tests. In the low season, the sensitivity of both tests dropped: 91.0% (95% CI 85.3-95.0) for the pLDH test and 85.8% (95% CI 79.3-90.9) for the HRP2 test. The positive predictive value remained low for both tests in the low season: 60.5% (95% CI 53.9-66.8) for the pLDH test and 61.9% (55.0-68.4) for the HRP2 test. Performance was similar across different production lots, gender, age of the children, and, during the high season, time since the most recent distribution of seasonal malaria chemoprevention. CONCLUSIONS: The low specificity of the pLDH RDT in this setting was unexpected and is not easily explained. As the pLDH test continues to be introduced into new settings, the questions raised by this study will need to be addressed.

Determinants of Visceral Leishmaniasis: A Case-Control Study in Gedaref State, Sudan.

BACKGROUND: Improving knowledge on local determinants of visceral leishmaniasis (VL) is crucial to guide the development of relevant control strategies. This study aimed to identify individual and household level determinants of primary VL in 24 highly endemic villages of Tabarak Allah hospital's catchment area, Gedaref State, Sudan. METHODS: From September 2012 to July 2013, in an unmatched case-control design, 198 patients with primary VL were compared to 801 controls free of VL symptoms and with a negative VL rapid test. Using random spatial sampling, controls were selected with a distribution of age, sex and village of residence proportionate to the distribution of the target population. Data were collected using a structured questionnaire. RESULTS: Children and men were at higher risk of VL. Reporting VL patient(s) in the household in the previous year was the strongest VL risk factor. In a multivariate analysis, VL risk increased with household size, sleep location (outside the yard, not in the farm), evening outdoor activities in the rainy season (playing, watching TV, radio listening), use of ground nut oil as animal repellent and of smoke of Acacia seyal as indoor repellent, presence of dogs in the yard at night, Acacia nilotica in the yard's immediate surroundings and of a forest at eye range. VL risk appeared to decrease with the use of drinking water sources other than the village water tank, a buffer distance from the adjacent house yard, and with the presence of animals other than dogs in the yard at night. In contrast with previous studies, housing factors, mosquito-net use, black cotton soil, ethnicity, socioeconomic index, presence of Balanites aegyptica and Azadirachta indica in the yard were not independent VL determinants. DISCUSSION AND CONCLUSION: Although these results do not provide evidence of causality, they provide useful suggestions for guiding further intervention studies on VL preventive measures.

Sodium stibogluconate and paromomycin for treating visceral leishmaniasis under routine conditions in eastern Sudan.

OBJECTIVES: Among patients with primary and relapse visceral leishmaniasis (VL) in eastern Sudan, we determined the proportion eligible for treatment with sodium stibogluconate and paromomycin (SSG/PM) and, of these, their demographic and clinical characteristics; initial treatment outcomes including adverse side effects requiring treatment discontinuation; treatment outcomes by 6 months; and risk factors associated with initial (slow responders) and late treatment failure (relapses and post-kala-azar dermal leishmaniasis, PKDL). METHODS: A retrospective cohort study in Tabarak Allah Hospital, Gedaref Province, eastern Sudan, from July 2011 to January 2014. RESULTS: Of 1252 individuals diagnosed with VL (1151 primary and 101 relapses), 65% were eligible for SSG/PM including 83% children, almost half of them malnourished and anaemic. About 4% of individuals discontinued treatment due to side effects; 0.7% died during treatment. Initial cure was achieved in 93% of 774 primary cases and 77% of 35 relapse cases (P < 0.001). Among the 809 patients eligible for SSG/PM, 218 (27%) were lost to follow-up. Outcomes by six months among the 591 patients with available follow-up data were: definitive cure (n = 506; 86%), relapse (n = 38; 6%), treatment discontinuation (n = 33; 6%), PKDL (n = 7; 1%) and death (n = 7; 1%). Among those completing a full course of SSG/PM, relapses and under-fives were at significantly higher risk of early and late treatment failure, respectively. CONCLUSION: Whether SSG/PM as a first-line regimen is an undeniable progress compared to SSG monotherapy, it excluded a considerable proportion of VL patients due to drug safety concerns. We call for accelerated development of new drugs and treatment regimens to improve VL treatment in Sudan.

Liposomal amphotericin B for complicated visceral leishmaniasis (kala-azar) in eastern Sudan: how effective is treatment for this neglected disease?

OBJECTIVES: The aim of this study was to report the patient profile and treatment outcomes, including relapses, of patients with visceral leishmaniasis (VL) treated with liposomal amphotericin B (AmBisome) in Gedaref, Sudan. METHODS: AmBisome was offered to two groups of patients: primary VL patients with specific criteria (age ≤2 or ≥45 years, advanced clinical disease, pregnancy, HIV co-infection and contraindications for antimonials) and VL relapses. AmBisome was given at a total dose of 30 mg/kg, over 10 days. Slow responders received up to 50 mg/kg. Treatment failure was confirmed parasitologically. Standardised treatment outcomes were assessed. RESULTS: Between March 2010 and June 2012, a total of 281 (74%) patients with primary VL and 98 (26%) patients with VL relapses received AmBisome (54% male, median age = 11 years, interquartile range 2-30). End-of-treatment outcomes for primary VL were 260 (92%) initial cure including three (1%) slow responders, three (1%) treatment failures, 14 (5%) deaths and four (1%) unknown outcomes. Outcomes for VL relapses were 92 (94%) initial cure with five (5%) slow responders, four (4%) treatment failures, one (1%) death and one (1%) unknown outcome. At 6 months, there were 19 (7%) relapses amongst primary VL and 10 (10%) VL relapses had a new relapse. Loss to follow-up in both groups was 38%. None of the deaths that occurred during the study period was attributed to AmBisome. CONCLUSION: AmBisome appears to be effective for initial cure of VL and the drug seems safe, but is expensive (400 USD/treatment). Sustained mechanisms to allow improved access of this expensive drug particularly in East Africa are urgently needed. Relapses and losses to follow-up require specific investigation.