The South West Monsoon rains arrived in Myanmar round about the last week of May. At that time the average temperature is high with high humidity, ideal conditions for insects to thrive. The insects which are vectors of diseases in Myanmar are mainly the mosquitoes. They breed in collections of water like lakes, ponds, rivers, streams, paddy fields, stagnant drains, water storage pots and vessels, even in puddles and small collections in upturned coconut husks, tins, bottles and flower vases in alters. Some even breed in small collection of water in stems of banana leaves and animal foot prints.
The three species of mosquitoes which are vectors of diseases in Myanmar are Anopheles, Culex and Aedes. The most prevalent and deadly vector borne disease in Myanmar as we all know is Malaria. It is transmitted by Anopheles species mosquitoes which are night biting mosquitoes (generally between dusk and dawn) mainly breed in running water of irrigation channels, streams, rivers, foothill and coastal areas. Malaria control program is one of the priority disease control program in Myanmar. Introducing use of insecticide-treated mosquito nets (ITN) or long-lasting insecticidal nets (LLIN) resulted in a sharp drop in transmission and incidence of disease. We have tried to eradicate Malaria at one time but the ecological situations being as it is we have to be content with controlling the disease. An article addressing uncomplicated malaria in Myanmar – Bangladesh border is also presented in this issue.
Aedes species mosquitoes are daytime feeders and are the vectors of viral diseases Chikungunya, Dengue, Dengue Haemorrhagic Fever (DHF) diseases. Aedes species breed in clear collections of water in and around human habitation. Their favourite breeding places are water storage pots, flower pots in alters (Buddha pedestals), small collections of water in old tyres, coconut husks, upturned tins and discarded utensils in and around the houses. Some species even breed in small collections of water in stem of banana leaves. The need to store water in houses because of no constant water supply system is one of the predisposing factors.Among these three diseases DHF, because of its potential to cause high fatality mostly in children, is a disease of national importance and one can see preventive measures being advocated quite frequently in newspapers and journals. Incidence of DHF tends to have a cyclical trend, coming to a peak every two years. 2020 appears to be the year where the rise in incidence is expected and MOHS is advocating proactively for preventive and control measures among the public. This MJCMP issue will also contain articles on DHF epidemiology, prevention and treatment.
Culex species are night biting mosquitoes and are vectors of Filariasis, a helminthic disease, and Japanese Encephalitis (JE), a viral disease which may prove fatal if left untreated. Species transmitting Filariasis breed in septic tanks and clogged drains, while species transmitting JE breed in paddy fields and sometimes in small collection of water in dykes, and even footprint of cattle and buffaloes. Filariasis produces lymphangitis, lymphadenitis resulting in disfiguring elephantiasis (elephant legs) which is not uncommon previously but rarely seen nowadays. JE is characterized by high fever, disorientation, neck stiffness, seizures, coma which can be fatal. In general Filariasis is an urban disease while JE is a rural one.
Apart from JE, where a potent vaccine is available, prevention of others depend on preventing contact between the vector and susceptible human hosts, which in reality is not very easy. As the economic situation of the country gets better together with rise in living standards, people become more informed of vector borne diseases and the environmental sanitation improved, the contact between the vector and human hosts will be lessened thus reducing the transmission of vector borne diseases. Together with early diagnosis of the diseases and effective treatment, vector borne diseases will then become less of a problem for the country as a whole.It is hoped that we may look forward to such development in the not too distant future.
