Calvin Tonga

An Update of Asymptomatic Falciparum Malaria in School Children in Muea, Southwest Cameroon

Despite efforts put in by the international community to reduce malaria burden in Africa, the disease especially that is caused by Plasmodium falciparum, still remains a major health problem in sub-Saharan Africa. A cross-sectional study involving 366 pupils was conducted in Muea, Southwest Cameroon to assess an update of the burden of falciparum malaria in school children. Capillary blood samples were collected and Giemsa-stained blood films were observed microscopically for the identification and quantification of malaria parasites. Capillary tubes were filled with blood and spun at 10,000 rpm for 5 minutes, for the determination of packed cell volume (PCV). The overall prevalence of asexual parasites and anaemia were compared with the values, previously reported in a similar study at the same site in 2005. The overall prevalence of P. falciparum asexual parasites was 44.26%, as opposed to a value of 98% reported in 2005. The prevalence of asexual parasites significantly decreased with age (X 2 =20.86, p<0.0001). The values were similar in the sexes. The overall geometric mean parasite density (GMPD) of asexual P. falciparum was 1490.00 ± 1674.92 and the value was similar in the sexes and age groups. P. falciparum gametocyte prevalence was 17.49% and the value decreased significantly with age (X 2 =22.88, p< 0.0001). The overall GMPD of gametocytes was 23.48 ± 6.96 parasites/ µl. Gametocytaemia decreased with age and the difference was significant (F=62.61, p<0001). The overall prevalence of anaemia was 3.83%, as opposed to 10.6% in 2005. Generally, there was a significant drop in prevalence of asexual malarial parasites and anaemia in school children, compared to the previously reported values in 2005, and this is ascribed to the use of intervention strategies in recent years in the area.

Environmental Factors and Preventive Methods against Malaria Parasite Prevalence in Rural Bomaka and Urban Molyko, Southwest Cameroon

Malaria remains a major public health problem in Cameroon. This work was aimed at determining the influence of environmental factors and control measures on malaria parasite prevalence, and anaemia in pupils in rural Bomaka and urban Molyko, Southwest Cameroon. A total of 303 pupils (174 and 129 from Bomaka and Molyko, respectively), aged 4-15 years were studied. Information on demographic data, environmental and anti-malarial measures was recorded. Malaria was diagnosed from Giemsa-stained blood smears. Packed Cell Volume (PCV) was determined. The overall malaria parasite prevalence was 33.0%, and children from Bomaka had a significantly higher value (38.51%) than those from Molyko (25.58%). Malaria parasite prevalence was significantly higher in males and highest in children aged ≤ 6 years. Overall location, age and stagnant water were associated with malaria parasite prevalence. Although malaria parasite prevalence was higher in pupils who had bushes around their homes, lived in plank houses, and did not use Insecticide Residual Spraying (IRS), the differences were, however, not significant. The overall prevalence of anaemia was 14.0%, with the ≤ 6 years old pupils having the highest anaemia prevalence. Parasite density was significantly higher in anaemic ((1369, CI=504.25-2511.89) than non-anaemic children ((507, CI=313.74-603.32). A combination of environmental and preventive measures (especially in rural areas) as well as community participation will reduce malaria transmission.

Anopheles gambiae, vecteur majeur du paludisme à Logbessou, zone péri-urbaine de Douala (Cameroun)

An entomological survey was carried out from August to November 2013, in order to determine the vector system of a building site for social housing in a coastal periurban district of Douala (Cameroon). Mosquito larvae were collected and adult endophilic mosquitoes captured on volunteers, for a total sample of 4897 mosquitoes. Morpho-taxonomic techniques alongside molecular techniques enabled the identification of 4 species, all aggressive to humans: Cx. pipiens (22.3%), Ae. albopictus (0.3%), An. coluzzii and An. gambiae (77.4%). The overall average biting rate recorded was 41.73 bites/person/night (b/p/n). An. gambiae s.l. represents 90.82% of this aggressive fauna, followed by Cx. pipiens (8.58%) and Ae. albopictus (0.6%). The detection of CSP showed that An. gambiae was responsible for 100% of P. falciparum transmission. The overall mean Entomological Inoculation Rate (EIR) was 3.94 ib/p/n. Female An. gambiae mortality rates were 14.47%, 82.5% and 100% respectively with DDT, permethrin and deltamethrin. The proliferation of An. gambiae in this area during raining season, at the detriment of An. coluzzii Coetze & Wilkerson and An. melas Theobald known to be major malaria vectors in island and coastal areas of Africa, may owe to the forest that still colonises this coastal peri-urban locality. Residents should therefore make use of deltamethrin based protective measures.

Mosquito Species Diversity and Malaria Transmission in Ayos, an Area of Degraded Forest Targeted for Universal Long-Lasting Insecticidal Net Distribution in Southern Cameroon

This study was conducted from January to December 2010 to evaluate the anopheline diversity and transmission of malaria in Ayos, a degraded forest area in the south of Cameroon, targeted for the distribution of long-lasting insecticidal nets (LLINs). Mosquito larvae were collected by the dipping method and endophilic female adult mosquitoes were captured on volunteers. Molecular techniques were used alongside morphological techniques for mosquito identification; ELISA was used for the detection of plasmodium circumsporozoite antigens. Ten mosquito species, including four Anopheles species (Anopheles gambiae s.s., An. funestus s.s., An. moucheti s.s. and An. hancocki), were identified. The mean biting rate of these Anopheles species was 12.7 bites per person per night (b/p/n). An. gambiae s.s. (6.9 b/p/n) appeared to be the most aggressive species. Malaria transmission is mainly ensured by An. gambiae s.s., An. funestus ss. and An. moucheti s.s. Plasmodium falciparum was the only malaria parasite transmitted. The mean entomological inoculation rate (EIR) for these vectors was 0.7 infecting b/p/n. An. gambiae s.s. (65.6 %) is the major vector, with an annual EIR of 167.9 infectious b/p/n/year. The utilization of LLINs alongside other methods would highly contribute to effective malaria control in Ayos.

Active Case Detection and Prevalence of Urinary Schistosomiasis and Malaria in Pupils of Kotto Barombi, Southwest Cameroon using the CyScope® Fluorescence Microscope

This work was carried out in collaboration between all authors. Author HKK designed the study and wrote the protocol, carried out field and laboratory work and wrote the first draft of the manuscript. Author GBW designed the study, wrote the protocol, carried out field work, read and corrected the manuscript. Author JAK designed the study, read and corrected the manuscript. Author CT performed the statistical analysis, read and corrected the manuscript. Authors BA, CN, LKN and HNN participated in the data collection and literature searches. Author LGL designed the study wrote the protocol, carried out field work and supervised the work at all stages. All authors read and approved the final manuscript.

Impact of vegetable crop agriculture on anopheline agressivity and malaria transmission in urban and less urbanized settings of the South region of Cameroon

BackgroundThe use of inland valley swamps for vegetable crop agriculture contributes to food security in urban and less urbanized settings in Africa. The impact of this agriculture on aggressive mosquitoes’ diversity and malaria transmission in central Africa is poorly documented. This study is aimed at assessing the impact of vegetable crop agriculture on these entomological parameters in urban and less urbanized settings of the forest area, south of Cameroon.MethodsThe human bait technique was used for the capture of aggressive mosquitoes from January to December 2012. For three consecutive days each month, captures were performed on volunteers in hydro-agricultural and river bank sites of Akonolinga and Yaoundé. Physico-chemical characteristics of mosquito breeding sites were recorded. Molecular alongside morpho-taxonomic techniques were used for the identification of mosquito species; ELISA test was used to reveal Plasmodium falciparum infected mosquitoes through the detection of CSP. Mosquito diversity, aggressivity and malaria transmission in sites and settings were determined and compared.ResultsBiting rates were higher in hydro-agricultural sites of less urbanized and urban settings (31.8 b/p/n and 28.6 b/p/n respectively) than in river banks sites (6.83 b/p/n and 3.64 b/p/n respectively; p < 0.0001). Physico-chemical parameters of breeding sites were not fundamentally different. Five anopheline species were identified; An. gambiae, An. funestus s.s., An. moucheti s.s., An. hancocki and An. nili s.s. In hydro-agricultural sites 2 species were captured in the urban setting versus 4 in the less urbanized setting, meanwhile in river bank sites, 3 species were captured in the urban setting versus 4 species in the less urbanized setting. An. nili s.s. was found in river banks only. An. hancocki was not found to insure Plasmodium falciparum Welch transmission. EIR in hydro-agricultural sites varied from 1.86 ib/p/n (urban area) to 2.13 ib/p/n (less urbanized area) with higher rates in April/May and August. Overall, EIR was higher in less urbanized areas (p < 0.0001) but the difference was nullified with the practice of vegetable crop agriculture (p = 0.2).ConclusionThese results highlight the need for specific preventive measures that take into account the ecological peculiarities related to vegetable crop agriculture on hydro-agricultural lands, in order to protect inhabitants from malaria.

[Anopheles gambiae, major malaria vector in Logbessou, a peri-urban area of Douala (Cameroon)].

An entomological survey was carried out from August to November 2013, in order to determine the vector system of a building site for social housing in a coastal periurban district of Douala (Cameroon). Mosquito larvae were collected and adult endophilic mosquitoes captured on volunteers, for a total sample of 4897 mosquitoes. Morpho-taxonomic techniques alongside molecular techniques enabled the identification of 4 species, all aggressive to humans: Cx. pipiens (22.3%), Ae. albopictus (0.3%), An. coluzzii and An. gambiae (77.4%). The overall average biting rate recorded was 41.73 bites/person/night (b/p/n). An. gambiae s.l. represents 90.82% of this aggressive fauna, followed by Cx. pipiens (8.58%) and Ae. albopictus (0.6%). The detection of CSP showed that An. gambiae was responsible for 100% of P. falciparum transmission. The overall mean Entomological Inoculation Rate (EIR) was 3.94 ib/p/n. Female An. gambiae mortality rates were 14.47%, 82.5% and 100% respectively with DDT, permethrin and deltamethrin. The proliferation of An. gambiae in this area during raining season, at the detriment of An. coluzzii Coetze & Wilkerson and An. melas Theobald known to be major malaria vectors in island and coastal areas of Africa, may owe to the forest that still colonises this coastal peri-urban locality. Residents should therefore make use of deltamethrin based protective measures.

Anopheles gambiae, vecteur majeur du paludisme à Logbessou, zone péri-urbaine de Douala (Cameroun)@@@Anopheles gambiae, major malaria vector in Logbessou, a peri-urban area of Douala (Cameroon)

An entomological survey was carried out from August to November 2013, in order to determine the vector system of a building site for social housing in a coastal periurban district of Douala (Cameroon). Mosquito larvae were collected and adult endophilic mosquitoes captured on volunteers, for a total sample of 4897 mosquitoes. Morpho-taxonomic techniques alongside molecular techniques enabled the identification of 4 species, all aggressive to humans: Cx. pipiens (22.3%), Ae. albopictus (0.3%), An. coluzzii and An. gambiae (77.4%). The overall average biting rate recorded was 41.73 bites/person/night (b/p/n). An. gambiae s.l. represents 90.82% of this aggressive fauna, followed by Cx. pipiens (8.58%) and Ae. albopictus (0.6%). The detection of CSP showed that An. gambiae was responsible for 100% of P. falciparum transmission. The overall mean Entomological Inoculation Rate (EIR) was 3.94 ib/p/n. Female An. gambiae mortality rates were 14.47%, 82.5% and 100% respectively with DDT, permethrin and deltamethrin. The proliferation of An. gambiae in this area during raining season, at the detriment of An. coluzzii Coetze & Wilkerson and An. melas Theobald known to be major malaria vectors in island and coastal areas of Africa, may owe to the forest that still colonises this coastal peri-urban locality. Residents should therefore make use of deltamethrin based protective measures.