Intestinal schistosomiasis in chimpanzees on Ngamba Island, Uganda: observations on liver fibrosis, schistosome genetic diversity and praziquantel treatment

Abstract

SUMMARYDespite treatment with praziquantel (PZQ) at 40 mg/kg in food, several chimpanzees on Ngamba Island Chimpanzee Sanctuary (NICS) continue to excrete eggs of Schistosoma mansoni. To monitor disease, 8 animals were closely examined under anaesthesia in March 2011 with portable ultrasonography and by rectal snip biopsy. Schistosome genetic diversity had been previously assayed within 4 of these chimpanzees, finding extensive diversity with 27 DNA barcodes encountered, although none was common to all animals. Calcified schistosome eggs were found in the rectal snips from 5 chimpanzees and liver fibrosis was clearly documented, indicative of progressive disease in 6 animals, the latter being surprisingly advanced in a younger chimpanzee. All 8 animals were treated under anaesthesia by oral gavage with PZQ at 60 mg/kg dosing that was well tolerated. These animals were again re-examined in June 2012 using stool and urine sampling. Only 1 chimpanzee appeared to be free from infection and active egg excretion was confirmed in 6 animals. If intestinal schistosomiasis is to be controlled within this setting, a long-term disease management plan is required which should combine active case-detection with an insistent treatment regime with praziquantel for these chimpanzees, exploring perhaps the performance of even higher dosing.

Schistosomiasis in pre-school-age children and their mothers in Chikhwawa district, Malawi with notes on characterization of schistosomes and snails

“…In order to retrieve schistosome eggs for DNA barcoding, pooled stool or urine samples were obtained from infected children at Kapsasule, Mpangeni and Mwaliga ( see Figure 1) and processed as previously decribed [39-41]. Eggs or hatched miracidia were harvested by pippette in 3 μl of water then placed onto FTA indicator cards.…”

“…From the FTA punch material, a 956 bp region of the mitrochondrial cyctochrome oxidase subunit 1 ( cox 1) gene, or DNA barcode, was amplified for S. haematobium in separate 25 μl PCR reactions using illustraTM puReTaq Ready-To-Go PCR Beads (GE Healthcare, UK) and 10 pmol of each primer (Forward primer: COX1_Schisto_5′; Reverse primer; COX1_Schist_3) [40]. For S. mansoni , a 540 bp fragment was amplified or 3 μl of genomic DNA using the ASMIT1 and Cox1_Schist_3′ primers and illustra™ puReTaq Ready-To-Go PCR Beads (GE Healthcare) [39]. Amplification products were later sequenced in both forward and reverse directions for assembly as edited with Sequencher ver.…”

Schistosoma mansoni in Gabon: Emerging or Ignored?

“…3,4 Recently, a semicaptive population of chimpanzees on Ngamba Island in the Lake Victoria (Uganda) was found to be infected by S. mansoni, probably as a result of contact with the S. mansoni-infected human population. 5 Herein, we report finding S. mansoni in free-ranging western lowland gorillas (Gorilla gorilla gorilla) and central chimpanzees (Pan troglodytes troglodytes) in Loango National Park (LNP), Gabon.…”

“…2 The local epidemiology of schistosomiasis in Ngamba Island Chimpanzee Sanctuary in Uganda was classified as "a shifting balance between anthropozoonotic and zoonotic cycles." 5 Although S. mansoni is broadly distributed across equatorial Africa, 2 to our knowledge, there are no reliable data on its occurrence in Gabon or its neighboring countries (e.g., Equatorial Guinea or the Republic of the Congo). The only reported cases of schistosomiasis in Gabon were caused by S. haematobium and S. guineensis (formerly S. intercalatum) and are only known from human population.…”

“…14 Clinical studies confirmed that the course and morbidity of S. mansoni infection in chimpanzees strongly resembles that reported for humans, including severe liver fibrosis. [3][4][5] In case of LNP gorillas and chimpanzees, the data on clinical significance of the schistosomiasis are indeed missing and possible impact of this disease on already endangered apes urgently requires further investigation. A detailed epidemiological study assessing the occurrence of S. mansoni in humans and great apes, as well as in its snail host, in and around LNP is critical for uncovering the ecology of this disease and its significance for local human population and LNP visitors.…”