Some strains of Plasmodium falciparum, a human malaria parasite, evade the complement-like system of Anopheles gambiae mosquitoes.

Plasmodium falciparum lines differ in their ability to infect mosquitoes. The Anopheles gambiae L3-5 refractory (R) line melanizes most Plasmodium species, including the Brazilian P. falciparum 7G8 line, but it is highly susceptible to some African P. falciparum strains such as 3D7, NF54, and GB4. We investigated whether these lines differ in their ability to evade the mosquito immune system. Silencing key components of the mosquito complement-like system [thioester-containing protein 1 (TEP1), leucine-rich repeat protein 1, and Anopheles Plasmodium-responsive leucine-rich repeat protein 1] prevented melanization of 7G8 parasites, reverting the refractory phenotype. In contrast, it had no effect on the intensity of infection with NF54, suggesting that this line is able to evade TEP1-mediated lysis. When R females were coinfected with a line that is melanized (7G8) and a line that survives (3D7), the coinfection resulted in mixed infections with both live and encapsulated parasites on individual midguts. This finding shows that survival of individual parasites is parasite-specific and not systemic in nature, because parasites can evade TEP1-mediated lysis even when other parasites are melanized in the same midgut. When females from an extensive genetic cross between R and susceptible A. gambiae (G3) mosquitoes were infected with P. berghei, encapsulation was strongly correlated with the TEP1-R1 allele. However, P. falciparum 7G8 parasites were no longer encapsulated by females from this cross, indicating that the TEP1-R1 allele is not sufficient to melanize this line. Evasion of the A. gambiae immune system by P. falciparum may be the result of parasite adaptation to sympatric mosquito vectors and may be an important factor driving malaria transmission.

Non-fatal injuries among pediatric patients seeking care in an urban Ghanaian emergency department.

BACKGROUND: According to the World Health Organization (WHO), injuries represent the largest cause of death among people ages 140 -and contribute to a large burden of disease worldwide. The aims of this study were to characterize the prevalence and relative mechanism of injury among children seeking emergency care and describe the demographics at time of presentation among these children to inform further research in Ghana and sub-Saharan Africa. METHODS: A prospective cross-sectional survey of pediatric patients (n = 176) was conducted between 13 July 2009 and 30 July 2009 in the Accident and Emergency Center at Komfo Anoche Teaching Hospital (KATH) in Kumasi, Ghana. Participants were asked questions regarding demographics, insurance status, overall health, and chief complaint. RESULTS: Of the 176 patients surveyed, 66% (n = 116) presented for injuries. The mean age was 4.7 years (range 1.5 months to 17 years), and 68% (n = 120) were male. Of those presenting with injury, 43% (n = 50) had road traffic injuries (RTI). Of the RTIs, 58% (n = 29) were due to being an occupant in a car crash, 26% (n = 13) were pedestrian injuries, and 14% (n = 7) were from motorcycles. There was no significant difference in demographics, health status or indicators of socioeconomic status between injured and non-injured patients. CONCLUSIONS: Among pediatric patients presenting for acute care at KATH during the study time frame, the majority (n = 116, 66%) presented for injuries. To date, there are no studies that characterize pediatric patients that present for acute care in Ghana. Identifying injury patterns and collecting epidemiologic data are important to guide future research and educational initiatives for Emergency Medicine.