METHODS: From June 2013 through May 2014, diarrheal stool samples were collected at one national referral hospital in Thimphu, two regional referral hospitals in the eastern and central regions, and one general hospital in the western region of Bhutan. NoV was detected by reverse transcription-polymerase chain reaction (RT-PCR), by amplifying the capsid gene. The RT-PCR results were confirmed by nucleotide sequencing of the amplicons.
RESULTS: The proportion of NoV-positive stool samples was 23.6% (147/623), of which 76.9% were NoV GII and the remainders were NoV GI. The median age of infected children was 15.5 months, with a fairly balanced female: male ratio. NoV GII was most prevalent in the colder months (late November-mid April) and NoV GI had the highest prevalence in the summer (mid April-late September). Nucleotide sequencing was successful in 99 samples of GII strains. The most common genotypes were GII.3 (42.6%), GII.4 Sydney 2012 (15.8%), and GII.4 unassigned (11.9%). No GII.21 was found in any child in the present study. Phylogenetic analysis showed that GII.3 strains in the present study belonged to an independent cluster in lineage B. These strains shared an ancestor with those from different countries and Bhutanese strains circulating during 2010.
CONCLUSION: NoV remains an important cause of diarrhea among Bhutanese children. Genotype GII.3 from a single ancestor strain has spread, replacing the previously circulating GII.21. Current NoV genotypes are similar to the strains circulating worldwide but are primarily related to those in neighboring countries. NoV GII is prevalent during the cold season, while GI is prevalent during the summer. To develop a NoV infection control policy, further studies are needed.
METHODS: A systematic review identified P. vivax efficacy studies of chloroquine with or without primaquine published between January 2000 and March 2017. Individual patient data were pooled using standardised methodology, and the haematological response versus time was quantified using a multivariable linear mixed effects model with non-linear terms for time. Mean differences in haemoglobin between treatment groups at day of nadir and day 42 were estimated from this model.
RESULTS: In total, 3421 patients from 29 studies were included: 1692 (49.5%) with normal G6PD status, 1701 (49.7%) with unknown status and 28 (0.8%) deficient or borderline individuals. Of 1975 patients treated with chloroquine alone, the mean haemoglobin fell from 12.22 g/dL [95% CI 11.93, 12.50] on day 0 to a nadir of 11.64 g/dL [11.36, 11.93] on day 2, before rising to 12.88 g/dL [12.60, 13.17] on day 42. In comparison to chloroquine alone, the mean haemoglobin in 1446 patients treated with chloroquine plus primaquine was - 0.13 g/dL [- 0.27, 0.01] lower at day of nadir (p = 0.072), but 0.49 g/dL [0.28, 0.69] higher by day 42 (p 25% to 5 g/dL.
CONCLUSIONS: Primaquine has the potential to reduce malaria-related anaemia at day 42 and beyond by preventing recurrent parasitaemia. Its widespread implementation will require accurate diagnosis of G6PD deficiency to reduce the risk of drug-induced haemolysis in vulnerable individuals.
TRIAL REGISTRATION: This trial was registered with PROSPERO: CRD42016053312. The date of the first registration was 23 December 2016.
METHODS: A systematic review done in MEDLINE, Web of Science, Embase, and Cochrane Database of Systematic Reviews identified P vivax clinical trials published between Jan 1, 2000, and March 22, 2017. Principal investigators were invited to share individual patient data, which were pooled using standardised methods. Cox regression analyses with random effects for study site were used to investigate the roles of chloroquine dose and primaquine use on rate of recurrence between day 7 and day 42 (primary outcome). The review protocol is registered in PROSPERO, number CRD42016053310.
FINDINGS: Of 134 identified chloroquine studies, 37 studies (from 17 countries) and 5240 patients were included. 2990 patients were treated with chloroquine alone, of whom 1041 (34·8%) received a dose below the target 25 mg/kg. The risk of recurrence was 32·4% (95% CI 29·8-35·1) by day 42. After controlling for confounders, a 5 mg/kg higher chloroquine dose reduced the rate of recurrence overall (adjusted hazard ratio [AHR] 0·82, 95% CI 0·69-0·97; p=0·021) and in children younger than 5 years (0·59, 0·41-0·86; p=0·0058). Adding primaquine reduced the risk of recurrence to 4·9% (95% CI 3·1-7·7) by day 42, which is lower than with chloroquine alone (AHR 0·10, 0·05-0·17; p<0·0001).
INTERPRETATION: Chloroquine is commonly under-dosed in the treatment of vivax malaria. Increasing the recommended dose to 30 mg/kg in children younger than 5 years could reduce substantially the risk of early recurrence when primaquine is not given. Radical cure with primaquine was highly effective in preventing early recurrence and may also improve blood schizontocidal efficacy against chloroquine-resistant P vivax.
FUNDING: Wellcome Trust, Australian National Health and Medical Research Council, and Bill & Melinda Gates Foundation.