METHODS

The data on the prevalence of lymphatic filariasis in patients from four states of South India were retrieved from indiastat.com and National Health Mission (India) [8]. The obtained data is shown in Table 1. The regression analysis was performed using online tool viz., https://www.mathportal.org/calculators/statistics-calculator/correlation-and-regression-calculator.php [9]. The resulted regression line and equation are shown in the Figure 1.

RESULTS AND DISCUSSION

The tropical region of the world, particularly the southern hemisphere, is rich in flora and fauna due to its climatic conditions. Further, the insect-vectors are flourishing well in this well-populated zone of plants and animals. Hence, there is an enormous scope for zoonotic infections to transmit and spread across the mammalian species and humans. One such is the elephantiasis, a serious disfiguring disease due to the defined mosquitoes indicated in the introduction section. The mosquitoes are the intermediate host for filarial worms. While sucking the blood from the infected subjects, the microfilaria goes into the gut of the insect and settles in the salivary glands up to L3 stage (third instar). This stage of microfilariae is the infective stage which is carried to the naïve uninfected man once bitten by the microfilariae carrying mosquito. These transmitted microfilariae are of the size of RBC and keeps staying in the blood stream for a long period (yet to be defined in the literature) till they become adults, then they move to the lymphatic circulation where they reside and produce numerous eggs to continue its life-cycle. During this time the infected individuals face illness due to lymphedema. The MDA (drugs shown in the introduction section) recommended by WHO is being given in all the filarial endemic zones since the year 2000.

The resultant impact of MDA in all the four states of South India is shown in Table 1. Most importantly, as per the guidelines of WHO [1,6,9], the contribution of health workers in the dramatic reduction in the number of lymphatic filariasis patients is noteworthy. Among the four states reported, Andhra Pradesh is showing more number of affected cases. By 2021, as per the data from National Health Mission (NVBDCP) [8], the number of reported affected cases is found high in the state of Andhra Pradesh compared to the rest. The regression analysis of the data reveal that there is a linear decrease trend with a significant negative correlation value (r) = - 0.9031 with a regression equation Y=161.6 - 0.07973X, the regression model of which predicts 23,000 filarial cases in the state of Andhra Pradesh by the year 2024 which is a phenomenal decline of filarial cases from the year 1997 (Table 1) and thus paving the path to improve the public health of the community which would be further accentuated through prophylactic measures such as vaccination.

CONCLUSION

The number of recorded cases of lymphatic filariasis in the year 1997 in the state of Andhra Pradesh (India) is 15,40,000. Whereas by the year 2021 this number reduced to 42,343 as per the report from NVBDCP. This phenomenal decline in the filariasis cases must have been primarily due to the WHO guidelines & directions; and implementation programs by the health workers. In the present study, the regression model predicted 23,000 filarial cases by the year 2024 in the state of Andhra Pradesh. The risk of transmission of microfilariae due to the potential carriers (infected subjects) and insect vectors may further augment the situation, the same would be abated by implementing and planning the prophylactic vaccines (Table 1).

ACKNOWLEDGEMENTS

Authors acknowledge the Centre of Excellence, Department of Biotechnology, VFSTR for providing facilities during the tenure of the work included in the article.

• 
  Table 1