There is very low quality evidence indicating that doxycycline use may be associated with an increased risk of indigestion, photosensitivity, vomiting, and yeast infections, when compared with mefloquine and atovaquone-proguanil. Causal prophylaxis
Causal prophylactics target not only the blood stages of malaria, but the initial liver stage as well. This means that the user can stop taking the drug seven days after leaving the area of risk. Malarone and primaquine are the only causal prophylactics in current use. Regimens
Specific regimens are recommended by the WHO, UK HPA and CDC for prevention of P. falciparum infection. HPA and WHO advice are broadly in line with each other (although there are some differences). CDC guidance frequently contradicts HPA and WHO guidance. These regimens include:

doxycycline 100 mg once daily (started one day before travel, and continued for four weeks after returning);
mefloquine 250 mg once weekly (started two-and-a-half weeks before travel, and continued for four weeks after returning);
atovaquone/proguanil (Malarone) 1 tablet daily (started one day before travel, and continued for 1 week after returning). Can also be used for therapy in some cases.In areas where chloroquine remains effective:

chloroquine 300 mg once weekly, and proguanil 200 mg once daily (started one week before travel, and continued for four weeks after returning);
hydroxychloroquine 400 mg once weekly (started one to two weeks before travel and continued for four weeks after returning)What regimen is appropriate depends on the person who is to take the medication as well as the country or region travelled to.
Brachydactyly type D, also known as short thumb or stub thumb and inaccurately referred to as clubbed thumb, is a condition clinically recognised by a thumb being relatively short and round with an accompanying wider nail bed. The distal phalanx of affected thumbs is approximately two-thirds the length of full-length thumbs. It is the most common type of brachydactyly, or shortness of digits, affecting approximately 2–3% of the population, and is associated with the HOXD13 gene, located on chromosome 2q31.1

Physiology
Brachydactyly type D is a skeletal condition which exhibits a partial fusion or premature closing of the epiphysis with the distal phalanx of the thumb, according to Goodman et alia (1965). J.K. Breithenbecher (1923) found that distal phalanges of stub thumbs were one-half the length of full-length thumbs, while R.M. Stecher (1957) claimed that it is approximately two-thirds. The condition may either be unilateral (affecting one thumb) or bilateral (affecting both). Genetics
A genetic trait, brachydactyly type D exhibits autosomal dominance and is commonly developed or inherited independently of other hereditary traits. The condition is associated with the HOXD13 gene, which is central in digital formation and growth.Various other studies supported an autosomal dominant pattern with reduced penetrance. Hereditary trait
A 1965 scientific study in Israel found that 3.05% of Palestinians in Israel had one or two stub thumbs, compared with 1.57% among Ashkenazi as well as non-Ashkenazi Jews.