Assessing the Presence of Wuchereria bancrofti Infections in Vectors Using Xenomonitoring in Lymphatic Filariasis Endemic Districts in Ghana

Detection of Wuchereria bancrofti infection in mosquitoes in areas co-endemic with Brugia malayi in Balasore district, Odisha, India

Lymphatic filariasis (LF) is a crippling and disfiguring parasitic condition. India accounts for 55% of the world's LF burden. The filarial parasite Wuchereria bancrofti is known to cause 99.4% of the cases while, Brugia malayi accounts for 0.6% of the issue occurring mainly in some pockets of Odisha and Kerala states. The Balasore (Baleswar) district of Odisha has been a known focus of B. malayi transmission. We employed molecular xenomonitoring to detect filarial parasite DNA in vectors. In six selected villages, Gravid traps were used to collect Culex mosquitoes and hand catch method using aspirators was followed for collection of mansonioides. A total of 2903 mosquitoes comprising of Cx. quinquefasciatus (n = 2611; 89.94%), Cx. tritaeniorhynchus (n = 100; 3.44%), Mansonia annuliferea (n = 139; 4.78%) and Mansonia uniformis (n = 53; 1.82%) were collected from six endemic villages. The species wise mosquitoes were made into 118 pools, each with a maximum of 25 mosquitoes, dried and transported to the laboratory at VCRC, Puducherry. The mosquito pools were subjected to parasite DNA extraction, followed by Real-time PCR using LDR and HhaI probes to detect W. bancrofti and B. malayi infections, respectively. Seven pools (6.66%) of Cx. quinquefasciatus, showed infection with only W. bancrofti while none of the pools of other mosquito species showed infection with either W. bancrofti or B. malayi. Although the study area is endemic to B. malayi, none of the vectors of B. malayi was found with parasite infection. This study highlights the ongoing transmission of bancroftian filariasis in the study villages of Balasore district of Odisha and its implications for evaluating LF elimination programme.

Coverage of preventive measures and surveillance for neglected tropical diseases in hard-to-reach communities in Ghana

BACKGROUND

Neglected tropical diseases (NTDs) are a major public health burden which mainly affects poor populations living in tropical environments and hard-to-reach areas. The study sought to examine coverage of preventive efforts, and case surveillance for NTDs in hard-to-reach communities in Ghana.

METHODS

The study investigated treatment efforts for lymphatic filariasis (LF), and onchocerciasis and schistosomiasis/soil transmitted helminths (SCH/STH) at household level, in difficult-to-access communities in Ghana. A total of 621 households were sampled from 6 communities in the Western, Oti and Greater Accra regions.

RESULTS

Over 95% of the households surveyed were covered under mass drug administration (MDA) campaigns for lymphatic filariasis (LF) and onchocerciasis. More than 80% of households had received at least two visits by community drug distributors under the MDA campaigns in the last two years preceding the study. In addition, over 90% of households in the LF and onchocerciasis endemic communities had at least one member using anthelminthic medications under the MDA campaigns in the 12 months preceding the study. However, households where no member had taken anthelminthic medications in 12 months preceding the study were over 6 times likely to have someone in the household with LF.

CONCLUSIONS

This study determined that SCH/STH, LF and onchocerciasis are of serious public health concern in some communities in Ghana. There is an urgent need for holistic practical disease control plan involving both financial and community support to ensure total control of NTDs in difficult-to-access communities is achieved.

Finding and eliminating the reservoirs: Engage and treat, and test and treat strategies for lymphatic filariasis programs to overcome endgame challenges

Many lymphatic filariasis (LF) endemic countries, including Ghana, have successfully implemented mass drug administration (MDA) and made significant progress towards the elimination of the disease as a public health problem. Unfortunately, the existence of individuals who seldom or never take part in MDA pose a threat to this success, as they may serve as reservoirs of infection, re-infecting their communities. In this study we implemented strategies to identify and treat these individuals, while also assessing their level of infection, to inform programme actions. The study was undertaken in the Ahanta West hotspot district in Ghana, which has received more than 17 rounds of MDA. Through the community registers used in recording participation in MDAs, we identified and offered treatment to individuals who were ineligible or inadvertently missed the last MDA in April 2021 (Engage and Treat – E&T), or testing using the filariasis test strip followed by treatment to community members who for various reasons chose not to participate in the last MDA (Test and Treat – T&T). During the study, 23,879 individuals ranging from 5 to 98 years were reached, of whom 78% were not captured in the MDA register. Among the E&T group, 75.06% willingly received and swallowed the treatment drugs. The remaining 24.94% were offered testing followed by a re-engagement to receive the drug in the T&T group. Overall, 22,830 (95.61%) of participants were treated by either strategy. Of the participants in the T&T group, 516 (8.66%; 95% CI= 7.96 – 9.41) were positive by the FTS. The highest antigen prevalence was detected among children 5 to 10 years, with 16.59% (95% CI= 12.02 – 22.06) and 22.54% (95% CI= 17.11 – 28.74) among females and males, respectively. Mapping of the data revealed that most infections are in a few select communities. Of the 516 FTS positives, 27.33% reportedly missed MDA once, 18.41% missed MDA twice and 54.26% missed all of the last three MDAs. The main reasons for missing MDA included absence (25.49%), travel (21.24%), being unaware of MDA (20.27%), refusals to take the drug (10.65%), illnesses (7.07%) and fear of adverse events (6.13%). This study demonstrates that greater sensitization and engagement strategies, with a test and treat strategy reserved for the most hesitant individuals, could significantly increase the number of individuals who receive treatment and therefore help districts reach their elimination targets by reducing the remaining reservoir or infection. NTD programmes require new tools to help them identify, engage and treat these individuals, as part of their overall monitoring and evaluation strategy.

COVID-19 related perception among some community members and frontline healthcare providers for NTD control in Ghana

Introduction

The Coronavirus Disease 2019 (COVID-19) pandemic has resulted in a major breakdown of health service provision in the fight against neglected tropical diseases (NTDs). COVID-19 may impact NTDs service delivery in varied ways. As the Ghana NTD programme planned to resume MDA activities, we examined the COVID-19 related perceptions and practices among some community members and frontline health workers for NTD control activities in the country.

Methods

The study was conducted in seven communities in the Ahanta West district of Ghana. This was a qualitative study using in-depth interviews (IDI) and focus group discussions (FGDs) for data collection. Participants were purposively selected from varied backgrounds to represent both beneficiaries and service providers directly involved in NTD programme implementation. Trained and experienced qualitative data collectors conducted the FGD and IDI sessions in the local Twi language, while health worker sessions were conducted in English. Discussions were audio-recorded and transcribed directly into English. Data was analysed using an iterative process. The transcripts were pre-coded using the broad themes, entered into a computer using Microsoft Word, and then imported into the MAXQDA software for thematic content analysis to select relevant representative narratives for presentation.

Results

Participants were aware of the COVID-19 pandemic and referred to it appropriately as ‘coronavirus’, COVID-19, and often as ‘the new disease’. Though many respondents could not describe the route of transmission, most of them reported that it is transmitted through touch or sharing of common items. They reported some signs/symptoms like fever, headache and difficulty breathing, and prevention methods like the use of hand sanitiser, washing of hands and sneezing appropriately. Respondents have reported that COVID-19 has negatively affected their daily lives by limiting their movements and therefore work. It also came to light that COVID-19 has also negatively affected the NTD programme implementation, especially mass drug administration (MDA) activities, leading to the postponement of the yearly MDA. The COVID-19 pandemic has negatively affected clinic attendance; people are afraid that they may be tested for COVID-19 at the clinic.

Conclusion

COVID-19 has negatively affected the NTD programme. Education and the provision of personal protective equipment will be required to build the confidence of frontline care providers including community drug distributors and community members in order to enhance quality service and participation in future MDA activities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07084-0.

Assessing the Filariasis Causing Parasites in Adult Mosquitoes and the Vector Mosquito Larval Breeding in Selected Medical Officer of Health Areas in Gampaha District, Sri Lanka

The present study was conducted to determine the prevalence of filariasis causing parasites in adult mosquitoes and vector mosquito larval breeding in four Medical Officer of Health (MOH) areas in Gampaha district, Sri Lanka. Adult female mosquitoes at their resting places were collected using a prokopack aspirator operated twice a day from 7.00 am to 8.00 am and 8.00 pm to 9 pm in predetermined dates. Microfilarial worms in dissected mosquitoes were morphologically identified. Nine species of mosquitoes, namely, Culex quinquefasciatus, Cx. pipiens, Cx. fuscocephala, Cx. gelidus, Armigeres subalbatus, Mansonia uniformis, Ma. annulifera, Aedes aegypti, and Ae. Albopictus, were captured. A total of 1194 mosquito larvae were collected that belonged into three genera, namely, Culex (62.73%), Armigeres (25.62%), and Mansonia (11.64%), from blocked drains, polluted drains, blocked canals, large polluted water bodies, stagnant water bodies, marsh lands, rice field mudflats, and concrete pits. Large polluted water bodies (Shannon-Wiener diversity index/H' = 1.5591) were the most diversed habitat type. In breeding water, average pH mainly lied in between 6 and 8 and average dissolved oxygen ranged from 3 to 7 mg/L. Cx. quinquefasciatus and Armigeres subalbatus adult female mosquitoes captured from Kelaniya MOH area were positive for microfilariae and were identified as Wuchereria bancrofti and Dirofilaria repens, respectively. This study concludes possible lymphatic filariasis situation is in extremely very low level persistent (0.06%) where transmission cannot be sustained and is restricted only to isolated pockets in the study area. The zoonotic strains of filariasis causing subcutaneous dirofilariasis in humans by Dirofilaria repens is continuing to survive due to the presence of stray dogs that serve as reservoir hosts.

Biodiversity of mosquitoes and Mansonia uniformis as a potential vector of Wuchereria bancrofti in Hulu Sungai Utara District, South Kalimantan, Indonesia

BACKGROUND AND AIM

Lymphatic filariasis, also known as elephantiasis, still remains a problem in Indonesia. The primary causative species of this disease are the filarial worms Wuchereria bancrofti and Brugia spp. This study was conducted to identify the diversity of species and behavior of mosquitoes and to determine the mosquitoes that could be potential vectors of filariasis.

MATERIALS AND METHODS

Mosquito samples derived from Hulu Sungai Utara (HSU) district in the 2017 multicenter study conducted in Indonesia were used in this cross-sectional study. The diversity of mosquito species was analyzed using the Shannon-Wiener diversity index. Mosquitoes were identified based on their species, and their DNA was isolated by polymerase chain reaction (PCR). Transcription-insulated isothermal PCR method was used to detect microfilariae/filaria larvae in the mosquitoes.

RESULTS

Biodiversity was found in 14 species of mosquitoes belonging to five genera. The maximum number of mosquitoes was recorded from the species Mansonia dives, Culex vishnui, Culex quinquefasciatus, and Mansonia uniformis. W. bancrofti infection was detected in M. uniformis at an infectivity rate of 0.3% (n=311).

CONCLUSION

To the best of our knowledge, this is the first report of M. uniformis species as a vector of W. bancrofti in HSU district, Indonesia. More efficient and accurate studies are required to aid in the lymphatic filariasis elimination programs in this subregion.

Low transmission of Wuchereria bancrofti in cross-border districts of Côte d'Ivoire: A great step towards lymphatic filariasis elimination in West Africa

BACKGROUND

Lymphatic filariasis (LF) is widely endemic in Côte d'Ivoire, and elimination as public health problem (EPHP) is based on annual mass drug administration (MDA) using ivermectin and albendazole. To guide EPHP efforts, we evaluated Wuchereria bancrofti infection indices among humans, and mosquito vectors after four rounds of MDA in four cross-border health districts of Côte d'Ivoire.

METHODOLOGY

We monitored people and mosquitoes for W. bancrofti infections in the cross-border health districts of Aboisso, Bloléquin, Odienné and Ouangolodougou, Côte d'Ivoire. W. bancrofti circulating filarial antigen (CFA) was identified using filariasis test strips, and antigen-positive individuals were screened for microfilaremia. Moreover, filarial mosquito vectors were sampled using window exit traps and pyrethrum sprays, and identified morphologically at species level. Anopheles gambiae s.l. and Culex quinquefasciatus females were analyzed for W. bancrofti infection using polymerase chain reaction (PCR) technique.

PRINCIPAL FINDINGS

Overall, we found a substantial decline in W. bancrofti infection indices after four rounds of MDA compared to pre-MDA baseline data. CFA prevalence fell from 3.38-5.50% during pre-MDA to 0.00-1.53% after MDA interventions. No subjects had detectable levels of CFA in Ouangolodougou. Moreover, post-MDA CFA prevalence was very low, and below the 1% elimination threshold in Aboisso (0.19%) and Odienné (0.49%). Conversely, CFA prevalence remained above 1% in Bloléquin (1.53%). W. bancrofti microfilariae (Mf) were not found in Aboisso, Bloléquin, and Ouangolodougou, except for Odienné with low prevalence (0.16%; n = 613) and microfilaremia of 32.0 Mf/mL. No An. gambiae s.l. and Cx. quinquefasciatus pools were infected with W. bancrofti in Bloléquin and Ouangolodougou, while they exhibited low infection rates in Aboisso (1% and 0.07%), and Odienné (0.08% and 0.08%), respectively.

CONCLUSIONS

In cross-border areas of Côte d'Ivoire, LF infection indices in humans and mosquito vectors substantially declined after four rounds of MDA. CFA prevalence fell under the World Health Organization (WHO)-established threshold (1%) in Aboisso, Ouangolodougou and Odienné. Moreover, W. bancrofti prevalence in mosquitoes was lower than WHO-established threshold (2%) in all areas. This might suggest the interruption of W. bancrofti transmission, and possible MDA cessation. However, a formal transmission assessment survey (TAS) and molecular xenomonitoring in mosquito vectors should be implemented before eventual MDA cessation. However, MDA should pursue in Bloléquin where W. bancrofti infection prevalence remained above 1%. Our results provided important ramifications for LF control efforts towards EPHP in Côte d'Ivoire.