High Prevalence of Low-Level Parasitemia With Plasmodium vivax in Makira-Ulawa Province Presents a Challenge for the Diagnosis and Eradication of Malaria in Solomon Islands

Background: The low population-prevalence of trachomatous trichiasis and high prevalence of trachomatous inflammation–follicular (TF) provide contradictory estimates of the magnitude of the public health threat from trachoma in the Solomon Islands. Improved characterisation of the biology of trachoma in the region may support policy makers as they decide what interventions are required. Here, age-specific profiles of anti-Pgp3 antibodies and conjunctival scarring were examined to determine whether there is evidence of ongoing transmission and pathology from ocular Chlamydia trachomatis (Ct) infection. Methods: A total of 1511 individuals aged ≥1 year were enrolled from randomly selected households in 13 villages in which >10% of children aged 1–9 years had TF prior to a single round of azithromycin mass drug administration undertaken six months previously. Blood was collected to be screened for antibodies to the Ct antigen Pgp3. Tarsal conjunctival photographs were collected for analysis of scarring severity. Results: Anti-Pgp3 seropositivity was 18% in 1–9 year olds, sharply increasing around the age of sexual debut to reach 69% in those over 25 years. Anti-Pgp3 seropositivity did not increase significantly between the ages of 1–9 years and was not associated with TF (p=0.581) or scarring in children (p=0.472). Conjunctival scars were visible in 13.1% of photographs. Mild (p<0.0001) but not severe (p=0.149) scars increased in prevalence with age. Conclusions: Neither conjunctival scars nor lymphoid follicles were associated with antibodies to Ct, suggesting that they are unlikely to be a direct result of ocular Ct infection. Clinical signs of trachoma were prevalent in this population but were not indicative of the underlying rates of Ct infection. The current World Health Organization guidelines for trachoma elimination indicated that this population should receive intervention with mass distribution of antibiotics, but the data presented here suggest that this may not have been appropriate.

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Mutations ingyrAandgyrBamong Fluoroquinolone- and Multidrug-Resistant Mycobacterium tuberculosis Isolates

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01049-15 ◽

2016 ◽

Vol 60 (4) ◽

pp. 2090-2096 ◽

Cited By ~ 26

Author(s):

Jung-Yien Chien ◽

Wei-Yih Chiu ◽

Shun-Tien Chien ◽

Chia-Jung Chiang ◽

Chong-Jen Yu ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

East Asian ◽

Multidrug Resistant ◽

Molecular Techniques ◽

Content Type ◽

Low Level ◽

High Prevalence ◽

Mdr Tb ◽

High Level

ABSTRACTIn order to correlate the mutations inside the entiregyrAandgyrBgenes with the level of resistance to ofloxacin (OFX) and moxifloxacin (MFX) in isolates of multidrug-resistantMycobacterium tuberculosis(MDR-TB), a total of 111 isolates were categorized into OFX-susceptible (MIC, ≤2 μg/ml) and low-level (MIC, 4 to 8 μg/ml) and high-level (MIC, ≥16 μg/ml) OFX-resistant isolates and MFX-susceptible (MIC, ≤0.5 μg/ml) and low-level (MIC, 1 to 2 μg/ml) and high-level (MIC, ≥4 μg/ml) MFX-resistant isolates. Resistance-associated mutations inside thegyrAgene were found in 30.2% of OFX-susceptible and 72.5% and 72.2% of low-level and high-level OFX-resistant isolates and in 28.6% of MFX-susceptible and 58.1% and 83.9% of low-level and high-level MFX-resistant isolates. Compared with OFX-susceptible isolates, low-level and high-level OFX-resistant isolates had a significantly higher prevalence of mutations atgyrAcodons 88 to 94 (17.0%, 65.0%, and 72.2%, respectively;P< 0.001) and a higher prevalence of thegyrBG512R mutation (0.0%, 2.5%, and 16.7%, respectively;P= 0.006). Similarly, compared with MFX-susceptible isolates, low-level and high-level MFX-resistant isolates had a significantly higher prevalence of mutations atgyrAcodons 88 to 94 (14.3%, 51.6%, and 80.6%, respectively;P< 0.001) as well as a higher prevalence of thegyrBG512R mutation (0.0%, 0.0%, and 12.9%, respectively;P= 0.011). D94G and D94N mutations ingyrAand the G512R mutation ingyrBwere correlated with high-level MFX resistance, while the D94A mutation was associated with low-level MFX resistance. The prevalence of mutations atgyrAcodons 88 to 94 and thegyrBG512R mutation were higher among fluoroquinolone (FQ)-susceptible East Asian (Beijing) and Indo-Oceanic strains than they were among Euro-American strains, implying that molecular techniques to detect FQ resistance may be less specific in areas with a high prevalence of East Asian (Beijing) and Indo-Oceanic strains.

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Population genetics of Plasmodium falciparum and Plasmodium vivax and asymptomatic malaria in Temotu Province, Solomon Islands

Malaria Journal ◽

10.1186/1475-2875-12-429 ◽

2013 ◽

Vol 12 (1) ◽

pp. 429 ◽

Cited By ~ 37

Author(s):

Karen-Ann Gray ◽

Simone Dowd ◽

Lisa Bain ◽

Albino Bobogare ◽

Lyndes Wini ◽

...

Keyword(s):

Population Genetics ◽

Plasmodium Falciparum ◽

Plasmodium Vivax ◽

Solomon Islands ◽

Asymptomatic Malaria

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High Prevalence and Fixation of Plasmodium vivax dhfr/dhps Mutations Related to Sulfadoxine/Pyrimethamine Resistance in French Guiana

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.2009.81.19 ◽

2009 ◽

Vol 81 (1) ◽

pp. 19-22 ◽

Cited By ~ 13

Author(s):

Céline Barnadas ◽

Didier Ménard ◽

Christiane Bouchier ◽

Stéphane Picot ◽

Thierry Fusai ◽

...

Keyword(s):

Plasmodium Vivax ◽

French Guiana ◽

High Prevalence

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ret/PTC1 and ret/PTC3 in thyroid tumors from Chernobyl liquidators: comparison with sporadic tumors from Ukrainian and French patients

Endocrine Related Cancer ◽

10.1677/erc.1.00884 ◽

2005 ◽

Vol 12 (1) ◽

pp. 173-183 ◽

Cited By ~ 16

Author(s):

J Di Cristofaro ◽

V Vasko ◽

V Savchenko ◽

S Cherenko ◽

A Larin ◽

...

Keyword(s):

Thyroid Cancer ◽

Genetic Susceptibility ◽

High Rate ◽

Thyroid Tumors ◽

Chernobyl Fallout ◽

Low Level ◽

High Prevalence ◽

Sporadic Tumors

Like children exposed to Chernobyl fallout, the workers who cleaned up after the accident, also known as liquidators, have exhibited an increased incidence of thyroid cancer. A high prevalence of ret/PTC3 rearrangement has been found in pediatric post-Chernobyl thyroid tumors, but this feature has not been investigated in liquidator thyroid tumors. In this study we analyzed the prevalence of ret/PTC1 and ret/PTC3 in thyroid tumors from 21 liquidators, 31 nonirradiated adult Ukrainian patients, and 34 nonirradiated adult French patients. ret rearrangements in carcinomas were found in 83.3% of liquidators, 64.7% of Ukrainian patients, and 42.9% of French patients. The prevalence of ret/PTC1 was statistically similar in the three groups. The prevalence of ret/PTC3 was significantly higher in liquidators than in French patients (P = 0.03) but it was also high in nonirradiated Ukrainian patients who exhibited values intermediate between liquidators and French patients. In adenomas the prevalence of rearrangement was significantly higher in all Ukrainians than in French patients (P = 0.004). Like children exposed to Chernobyl fallout, liquidators showed a high prevalence of ret/PTC3. This finding suggests that irradiation had the same effect regardless of age. However, given the high rate of ret/PTC3 in nonirradiated adult Ukrainians, the possibility of genetic susceptibility or low-level exposure to radiation in that group cannot be excluded.

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Genetic mutations in Plasmodium falciparum and Plasmodium vivax dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) in Vanuatu and Solomon Islands prior to the introduction of artemisinin combination therapy

Malaria Journal ◽

10.1186/1475-2875-13-402 ◽

2014 ◽

Vol 13 (1) ◽

pp. 402 ◽

Cited By ~ 4

Author(s):

Karryn J Gresty ◽

Karen-Ann Gray ◽

Albino Bobogare ◽

Lyndes Wini ◽

George Taleo ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Combination Therapy ◽

Plasmodium Vivax ◽

Dihydrofolate Reductase ◽

Solomon Islands ◽

Artemisinin Combination Therapy ◽

Genetic Mutations ◽

Dihydropteroate Synthase

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Estimation of scabies prevalence using simplified criteria and mapping procedures in three Pacific and southeast Asian countries

BMC Public Health ◽

10.1186/s12889-021-12039-2 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Shu Ki Tsoi ◽

Susanna J. Lake ◽

Li Jun Thean ◽

Alexander Matthews ◽

Oliver Sokana ◽

...

Keyword(s):

Solomon Islands ◽

Skin Lesions ◽

Prevalence Estimation ◽

Informal Consultation ◽

Pooled Prevalence ◽

Significant Difference ◽

Timor Leste ◽

High Prevalence ◽

Considerable Morbidity ◽

Effective Public Health

Abstract Background Scabies causes considerable morbidity in disadvantaged populations. The International Alliance for the Control of Scabies (IACS) published consensus criteria in 2020 to standardize scabies diagnosis. However, these criteria are complex, and a WHO informal consultation proposed simplified criteria for mapping, to identify regions of high prevalence as targets for mass drug administration. We aimed to investigate the accuracy of simplified criteria in determining scabies prevalence, compared to the 2020 IACS criteria. Methods We obtained data relating to demographics, relevant history and skin lesions from all-age prevalence surveys from Fiji (n = 3365) and Solomon Islands (n = 5239), as well as school-aged children in Timor-Leste (n = 1043). We calculated prevalence using the 2020 IACS criteria and simplified criteria and compared these disease estimates. Results There was no significant difference in the pooled prevalence using the two methods (2020 IACS criteria: 16.6%; simplified criteria: 15.6%; difference = 0.9, [95% CI -0.1, 2.0]). In Timor-Leste, the prevalence using simplified criteria was lower (26.5% vs 33.8%). Simplified criteria had a sensitivity of 82.3% (95% CI 80.2, 84.2) and specificity of 97.6% (95% CI 97.2, 97.9) compared to the 2020 IACS criteria. Conclusions The scabies prevalence estimation using simplified criteria was similar to using the 2020 IACS criteria in high prevalence, tropical countries. The prevalence estimation was lower in the school-based survey in Timor-Leste. Mapping using simplified criteria may be a feasible and effective public health tool to identify priority regions for scabies control. Further work assessing use of simplified criteria for mapping in a field setting should be conducted.

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Genetic diversity, natural selection and haplotype grouping of Plasmodium vivax Duffy-binding protein genes from eastern and western Myanmar borders

Parasites & Vectors ◽

10.1186/s13071-019-3803-2 ◽

2019 ◽

Vol 12 (1) ◽

Cited By ~ 1

Author(s):

Yubing Hu ◽

Lin Wang ◽

Huguette Gaelle Ngassa Mbenda ◽

Myat Thu Soe ◽

Chunyun Yu ◽

...

Keyword(s):

Genetic Diversity ◽

Natural Selection ◽

Genetic Differentiation ◽

Plasmodium Vivax ◽

Binding Protein ◽

Duffy Binding Protein ◽

High Genetic Diversity ◽

Low Level ◽

Malaria Epidemiology ◽

Greater Mekong Subregion

Abstract Background Merozoite proteins of the malaria parasites involved in the invasion of red blood cells are selected by host immunity and their diversity is greatly influenced by changes in malaria epidemiology. In the Greater Mekong Subregion (GMS), malaria transmission is concentrated along the international borders and there have been major changes in malaria epidemiology with Plasmodium vivax becoming the dominant species in many regions. Here, we aimed to evaluate the genetic diversity of P. vivax Duffy-binding protein gene domain II (pvdbp-II) in isolates from the eastern and western borders of Myanmar, and compared it with that from global P. vivax populations. Methods pvdbp-II sequences were obtained from 85 and 82 clinical P. vivax isolates from the eastern and western Myanmar borders, respectively. In addition, 504 pvdbp-II sequences from nine P. vivax populations of the world were retrieved from GenBank and used for comparative analysis of genetic diversity, recombination and population structure of the parasite population. Results The nucleotide diversity of the pvdbp-II sequences from the Myanmar border parasite isolates was not uniform, with the highest diversity located between nucleotides 1078 and 1332. Western Myanmar isolates had a unique R391C mutation. Evidence of positive natural selection was detected in pvdbp-II gene in P. vivax isolates from the eastern Myanmar area. P. vivax parasite populations in the GMS, including those from the eastern, western, and central Myanmar as well as Thailand showed low-level genetic differentiation (FST, 0.000–0.099). Population genetic structure analysis of the pvdbp-II sequences showed a division of the GMS populations into four genetic clusters. A total of 60 PvDBP-II haplotypes were identified in 210 sequences from the GMS populations. Among the epitopes in PvDBP-II, high genetic diversity was found in epitopes 45 (379-SIFGT(D/G)(E/K)(K/N)AQQ(R/H)(R/C)KQ-393, π = 0.029) and Ia (416-G(N/K)F(I/M)WICK(L/I)-424], Ib [482-KSYD(Q/E)WITR-490, π = 0.028) in P. vivax populations from the eastern and western borders of Myanmar. Conclusions The pvdbp-II gene is genetically diverse in the eastern and western Myanmar border P. vivax populations. Positive natural selection and recombination occurred in pvdbp-II gene. Low-level genetic differentiation was identified, suggesting extensive gene flow of the P. vivax populations in the GMS. These results can help understand the evolution of the P. vivax populations in the course of regional malaria elimination and guide the design of PvDBP-II-based vaccine.

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High prevalence ofNeisseria gonorrhoeaein a remote, undertreated population of Namibian pastoralists

Epidemiology and Infection ◽

10.1017/s0950268813003488 ◽

2014 ◽

Vol 142 (11) ◽

pp. 2422-2432 ◽

Cited By ~ 9

Author(s):

A. HAZEL ◽

S. PONNALURI-WEARS ◽

G. S. DAVIS ◽

B. S. LOW ◽

B. FOXMAN

Keyword(s):

Social Activity ◽

Cross Sectional Study ◽

Cross Sectional ◽

Rural Villages ◽

Low Level ◽

Pastoralist Communities ◽

High Prevalence ◽

Vaginal Swabs ◽

Symptom History ◽

High Level

SUMMARYThe highly remote pastoralist communities in Kaokoland, Namibia, have long been presumed to have high gonorrhoea prevalence. To estimate gonorrhoea prevalence and correlates of infection, we conducted a cross-sectional study of 446 adults across 28 rural villages. Gonorrhoea status was determined from urethral and vaginal swabs via qPCR assay. All participants answered a closed-ended interview about demographics, sexual behaviour and symptom history. Sixteen per cent of participants had high-level infections (⩾ID50dose) and 48% had low-level infections (<ID50dose). Women had higher prevalence than men of both high- and low-level infections. High-level infections were regionally and seasonally clustered, occurring in young adults in the Ehama region during the winter. Low-level infections were distributed homogenously across demographic characteristics, season, and region. All low-level infections and most high-level infections (men 78%, women 95%) were asymptomatic and left untreated. The epidemic-like nature of high-level gonorrhoea cases suggests that intervention efforts can be focused on seasons of high social activity.

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