Department of Microbiology, Calcutta School of Tropical Medicine, Kolkata, Indiaa
Department of Tropical Medicine, Calcutta School of Tropical Medicine, Kolkata, Indiab
Department of Health and Family Welfare, Government of West Bengal, Swastha Bhavan, Salt Lake City, Kolkata, Indiac
Asymptomatic infection by Plasmodium falciparum is an important obstacle to eliminating malaria. Asymptomatic carriers do not seek treatment for infection, and therefore they become a reservoir for the parasite. For this reason, these carriers pose a real public health risk. The systematic identification and treatment of asymptomatic infections should reduce the parasite reservoir. A large reduction in this pool will lower the chance of transmission of the disease. In this study, we screened a tribal population of 1,040 individuals in the Purulia district of West Bengal by using a dual-antigen rapid diagnostic kit (RDK), microscopy, and species-specific PCR. All positive individuals were treated with artemisinin-based combination therapy (ACT) (artesunate plus sulfadoxine-pyrimethamine) and followed for 42 days. Polymorphisms in candidate genes were screened by DNA sequencing. A significant proportion (8.4%) of the study population was infected with P. falciparum but showed no clinical manifestations. The PCR method was more sensitive in detecting infection than the RDK or microscopy. The efficacy of the ACT was 97%. In the pfcrt gene, the mutation K76T (the mutated amino acid is indicated by bold type) was found in 100% of the cases. In the pfmdr1 gene, the mutations N86Y and Y184F were noted in 55.5% and 11% of the cases, respectively. Six different haplotypes were identified in the pfdhfr-pfdhps genes. Most importantly, the quintuple mutant A16I51R59N108I164-S436G437E540A581A613 was found in 10% of the isolates, which is potentially important for the development of sulfadoxine-pyrimethamine resistance. A significant proportion of the study population harboring P. falciparum does not seek treatment and therefore serves as a reservoir for the parasite, maintaining the natural cycle. If the National Vector Borne Disease Control Programme (NVBDCP) of India is to eliminate malaria, then this hidden parasite burden needs to be addressed properly. Similar study in other parts of the country could help to determine the magnitude of the problem.
After service in the British SAS Regiment the author became a physician and then an orthopaedic surgeon.
He has held professorial positions in Canada, Vietnam and the United States, practiced and taught orthopaedic surgery in three continents and in several wars.
He has extensive experience as an expert witness in court. Somewhere along the way, time was found to operate a four hundred acre mixed farm, a one hundred seat restaurant and to obtain a licence as a flying instructor.
The author's books are available from bookstores, the publishers, or from on-line bookstores such as Amazon, Barnes and Noble, and Indigo/Chapters.