Mosquito Bite and the Deadly Duo

Abstract

Avoiding a mosquito bite can prevent a number of viral as well as parasitic diseases like Chikungunya, Dengue,Japanese encephalitis, Rift valley fever, Yellow fever, Zika, Malaria and Lymphatic Filariasis. Of all theseinfections, malaria has been our nemesis right from the dawn of history. However, it is Dengue which has established itself as the most successful arthropod-borne viral infection not only in Pakistan but globally.1The first case of Dengue in Pakistan was reported in 1994 from Karachi, after which it went quiet for almosttwelve years to return in the form of an epidemic in 2006, which again remained limited to Karachi. However, itspread to many other parts of the country in the next few years on endemic scales.A person can get infected four times as the Dengue virus has four serotypes (DEN1, DEN2, DEN3 and DEN4) eachof which confers monotypic immunity. It is now a recognized acute febrile illness of the monsoon season (July-September), when a drop temperature and increased humidity provide optimal conditions for this urbandwelling, dawn and dusk, vector mosquito, Aedes aegypti. This vector now seems to be defying these climaticconditions as patients continue to report to hospitals in the winter months as well.The textbook diagnosis of Dengue looks simple; by detecting the virus either (by viral culture), its nucleic acid(by PCR), its components like the non-structural protein (NS-1), or the evidence of infection (IgM), or if none ofthese is available, then the surrogate markers like the typical bicytopenia showing reduced neutrophils andplatelets are indicators of the disease. Similarly, the clinical diagnosis is not very difficult once the epidemic isestablished, due to its peculiar symptoms like retro-orbital pain and body aches , so severe as if the bones willbreak, hence the name 'Break Bone' fever.Dengue is temporarily incapacitating but rarely fatal, and in Pakistan it has a case fatality rate around 0.4 percent.2 This low fatality rate should not lead to complacency as every life is precious. A few fundamentals,however, need emphasis especially for the young doctors and the medical staff attending the patients ofDengue. Like many other infectious diseases, Dengue follows the principle of the “tip of the iceberg”. Majorityof those infected with the virus, remain either asymptomatic or present with minimum symptoms including lowgrade fever. However, a small percentage of patients may proceed to the critical stage called the DengueHaemmorhagic Fever (DHF)/Dengue Shock Syndrome (DSS) and warrant special attention. These are basicallythe manifestations of underlying plasma leakage and it is this cohort of patients that are at an increased risk ofan adverse outcome.The parameter which helps in this situation is the packed cell volume (haematocrit), an increase of about 15% ofwhich is a reliable indicator of internal dehydration. DHF/DSS occur as a result of a second exposure by a different serotype, and a still not completely understood phenomenon, known as the Antibody Dependent Enhancement (ADE).Pakistan has barely recovered from the COVID19 pandemic, hit by the economic crisis and now unprecedentedfloods in Sindh and Baluchistan, where most parts are still inundated and are likely to be so for another severalweeks, we are indeed in a very difficult situation. An estimated 6.4 million people require immediate assistanceas around 1.96 million houses, 22,000 schools and 12,716 km of roads have been either destroyed or damagedin 81 districts.3 Ironically these two provinces have bulk of the country's falciparum malaria cases, which is themost lethal form with severe complications like heavy parasitaemia, cerebral malaria, black water fever andchloroquine resistance.
 Stagnant water all around the stranded people is a perfect mosquito breeding haven. It is difficult tocomprehend the plight of people now living along the roadside under a tent in hot and humid conditions, asthey are exposed twenty-four seven, either to the Dengue mosquito at dawn and dusk or, malaria causinganopheles mosquito at night.The magnitude of this problem is much bigger than the resources of any medical community and thegovernment. Spraying insecticides over this volume is logistically not feasible. The only practical solution isthe use of personal protective measures.Deaths from these two diseases along with gastroenteritis have already started to occur. The exact toll of thesemosquito bites will be written by the medical historians or the statisticians sometime in the future. It is theyouth of Pakistan which has once again risen to the occasion and is working relentlessly on volunteer basis, toreach out to these people not only providing them with mosquito nets and repellants but explaining theirproper use. This altruistic effort will definitely save many lives.Editor-in-ChiefHow to cite this: Alamgir W, Usman J. Mosquito Bite and the Deadly Duo. Life and Science. 2022; 3(4): 149-150. doi: http://doi.org/10.37185/LnS.1.1.288