Visceral leishmaniasis (VL) is the most serious form of human leishmaniasis. VL is understudied in West Africa. The increasing number of patients at-risk, including persons living with HIV and other chronic immunosuppressive diseases, and likely underreporting of VL related to diagnostic challenges advocate for review of existing data to understand VL regional epidemiology. Our review aims to describe the clinical characteristics and epidemiology of Human VL (HVL) in West Africa. We conducted a literature search to identify peer-reviewed articles and grey literature sources using the search terms “Visceral leishmaniasis West Africa”, “
VL is caused by a flagellated protozoan of the genus
The clinical features, vectors, and reservoirs of VL in West Africa are not well known. In this review, we aim to describe clinical and epidemiological profiles of VL in West Africa.
We conducted a literature search to identify records of VL in West Africa. The search included peer-reviewed manuscripts in both French and English using HINARI, Google Scholar, and PubMed, with the following terms: “Visceral leishmaniasis West Africa”; “
We conducted an exhaustive coverage strategy to find published and unpublished papers on VL in West Africa. The articles were selected by the first author if relevant to review subject. When full text was not available, the abstract was used. The coauthors verified these selected full text articles and abstracts for relevance. The data were extracted and grouped by clinical cases, reservoirs, and vectors.
The following data were extracted from each study: study location (country), patient population, clinical and laboratory characteristics at presentation, diagnosis tests performed, vectors (description of fauna), and potential parasite reservoirs.
Thirty relevant peer-reviewed manuscripts were found. Most original articles describing HVL dated from the early 2000’s and before, but articles describing reservoirs were between 2011 and 2017.
Cases of HVL and CVL were distributed all over West Africa (see Figure
Geographic distribution of CVL and HVL in West Africa 1949-2018 (made with Philcarto,
Status of visceral leishmaniasis worldwide 2016 [
Based on these records, two countries, Niger and Ivory Coast, reported the greatest number of HVL cases confirmed by microscopy or serology. Niger reported 21 cases, Ivory Coast reported eight cases, and the Gambia and Burkina Faso reported one case each. Most of these cases occurred more than ten years ago: one Togolese case was diagnosed in Lama-Kara (Northern region) in 1994; and in Nigeria suspected cases have been reported between 1936 and 1947 [
VL cases, vectors, and animals in West Africa.
Country/location | Cases | Vectors | Animals | |||
---|---|---|---|---|---|---|
Number | Date | Age (years) | sex | |||
Mali | 0 | no data | ||||
Senegal | 0 | no data | Sergentomyia sp. | Domestic dogs | ||
Niger | 94 | 1948-1991 |
|
|||
1 | Sep-92 | 23 | ||||
1 | Mar-93 | 24 |
|
|||
1 | Mar-93 | 30 | ||||
1 | Mar-93 | 36 | ||||
1 | Apr-93 | 37 | ||||
1 | Dec-94 | 25 | ||||
Nigeria | 1 | 2005 | ||||
2 | 2007 | |||||
57 | 2012 | Domestic dogs | ||||
The Gambia | 1 | 1949 | 15 | Male | ||
1 | 1980 | 6 | Female | |||
1 | 1982 | 6 | Female | |||
Burkina Faso | 1 | 1978 | Male | Domestic dogs | ||
Togo | 1 | 1994 | ||||
Guinea | 0 | no data | ||||
Guinea-Bissau | 1 | 1990 | ||||
Liberia | 0 | no data | ||||
Ghana | 0 | no data | ||||
Mauritania | 0 | no data | ||||
Cote d’Ivoire | 1 | 9-Jun-04 | 31 | Female | ||
1 | 14-Sep-04 | 65 | Female | |||
1 | 25-Apr-05 | 5 | ||||
1 | 2004 | 37 | Female | |||
1 | 2004 | 26 | Female | |||
Total | 171 |
HVL cases reported in West African are rare compared to other African endemic regions such as Eastern Africa. The status of
The characteristics of the parasite and sandflies species, the local ecological characteristics of the transmission sites, current and past exposure of the human population to the parasite, and human behavior determine Leishmaniasis epidemiology [
One article from Senegal described risk factors associated with HVL using data from a Western blot seroprevalence study, including age over 40 years and presence of infected dogs in the household and Nebedaye trees (
In the district of Mont-Rolland, Thiès, Senegal, HVL Western blot seroprevalence from a survey conducted in the entire population was 23% (73/315); but symptomatic cases were not diagnosed [
VL indirect hemagglutination test (IHA) screening using
Since 1948, around 168 cases of HVL have been identified in Niger. Among these, 12 had confirmatory testing by microscopy [
HVL exists in Algerian Sahara and in south of Algeria, as several cases of HVL have been observed at Hoggar (Central Sahara), and in the regions of Tamanrasset and Djanet [
HVL incidence at the University Hospital Center of Cocody in Abidjan, Ivory Coast, was 0.56% (3/528) over a one-year follow-up period (2001-2002) [
In Ivory Coast, HVL vectors are not described in the literature.
In Niger, vectors of
Dogs were confirmed reservoirs of HVL in West Africa [
A Nigerian seroprevalence survey indicated that VL is transmitted among domestic dogs. An increased seroprevalence 14.63% (6/41 dogs) was recorded in Kara state [
In addition to dogs, the role of mammals such as rodents as reservoirs of VL deserves further investigation in West African context. Recent studies implicated rodents as possible vectors of
VL reported in West Africa is mostly a zoonosis. HVL and CVL are widely distributed in West Africa, with eight countries affected (see Figure
Although HVL are no longer described from old foci such as Ivory Coast, The Gambia, and Niger [
In Niger, from 1948 to 1991 three HVL cases were confirmed by microscopy. From 1992 to 1995 six cases were described; common signs and symptoms at presentation included fever (n=4, jaundice (n=3), splenomegaly (n=1), weight loss (n=3), anorexia (n=4), and overall poor health status (n=5). Brucellosis and suspected liver cancer were associated with two of these HVL cases [
In Ivory Coast, Eholié
Kaoussi et al. described VL in Ivory Coast in three patients with potential predisposing conditions. One patient had a long course of systemic steroid therapy (2 months), and HIV infection was present in the two patients. Two of these three patients died [
Two cases were reported by Kacou et al. in Ivory Coast. The first patient had hepatomegaly and lymphadenopathy and had recently undergone 8-week systemic steroid therapy for medullar aplasia. He spent one month in a
In total, 17 cases of confirmed HVL have been identified, including four cases of coinfection VL/HIV, three in Ivory Coast, and one in Guinea Bissau [
Diagnosis is sometimes a challenge as HVL mimics viral infections, chronic malaria, leukemia, and autoimmune diseases. The presence of pancytopenia, a condition that evokes HVL [
Little data exists to guide VL treatment in West Africa. WHO does not have specific recommendations for VL treatment in West Africa, but for East Africa it recommends a 17-day combination therapy with sodium stibogluconate (SSG) plus paromomycin as first line therapy for VL caused by
The clinical presentation and prognosis of VL-HIV coinfection are not well described in the West African context compared to other areas. In the Mediterranean region, VL-HIV coinfection is characterized by decreased VL cure rates, and increased drug toxicity, increased relapse and mortality rates when compared with HIV-negative VL patients [
Our review suggests that VL is present in West Africa, albeit at a much lower level than in East Africa.
The authors declare that they have no conflicts of interest.
Abdoulaye K. Kone, Doumbo Safiatou Niaré, and Mahamadou A. Thera contributed in literature review. Mahamadou A. Thera, Matthew B. Laurens, Martine Piarroux, Renaud Piarroux, Pierre Marty, Arezki Izri, and Ogobara K. Doumbo contributed to critical review and editing of the manuscript. All authors participated in the preparation of the manuscript and approved the final version.